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  • AERODYNAMICS
  • Adaptation
  • 2005-2009  (3)
  • 1995-1999  (139)
  • 1980-1984  (2,115)
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  • 1
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    Advances in Applied Self-organizing Systems (2008)
    London : Springer
    Details
    Keywords: Adaptation ; Artificial Life ; Bio-inspired Computing ; Bio-inspired Robotics ; Collective Behaviour ; Complex Systems ; Decentralized Management ; Distrbuted Management ; Distributed Computing ; Emergence ; Evolutinary Algorithms ; Immune Networks ; Information Transfer ; Multi-agent Systems ; Pattern Formation ; Self-assembly ; Self-organization ; Self-organizing Computation
    Description / Table of Contents: The main challenge faced by designers of self-organizing systems is how to validate and control non-deterministic dynamics. Over-engineering the system may completely suppress self-organization with an outside influence, eliminating emergent patterns and decreasing robustness, adaptability and scalability. Whilst leaving too much non-determinism in the system’s behaviour may make its verification and validation almost impossible. This book presents the state-of-the-practice in successfully engineered self-organizing systems, and examines ways to balance design and self organization in the context of applications. As demonstrated throughout, finding this balance helps to deal with diverse practical challenges. The book begins with the more established fields of traffic management and structural health monitoring, building up towards robotic teams, solving challenging tasks deployed in tough environments. The second half of the book follows with a deeper look into the micro-level, and considers local interactions between agents. These interactions lead towards self-modifying digital circuitry and self-managing grids, self-organizing data visualization and intrusion detection in computer networks, immunocomputing and nature-inspired computation, and eventually to artificial life. The case studies described illustrate the richness of the topic and provide guidance to its intricate areas. Many algorithms proposed and discussed in this volume are biologically inspired and readers will also gain an insight into cellular automata, genetic algorithms, artificial immune systems, snake-like locomotion, ant foraging, birds flocking and mutualistic biological ecosystems, amongst others. Demonstrating the practical relevance and applicability of self-organization, this book will be of interest to advanced students and researchers in a wide range of fields.
    Pages: Online-Ressource (XI, 375 Seiten)
    ISBN: 9781846289828
    URL: http://www.springerlink.com/content/978-1-84628-981-1/
    Language: English
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    E-BOOK
  • 2
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    Thermal adaptation of soil microbial respiration to elevated temperature (2009)
    Details
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Blackwell for personal use, not for redistribution. The definitive version was published in Ecology Letters 11 (2008): 1316-1327, doi:10.1111/j.1461-0248.2008.01251.x.
    Description: In the short-term heterotrophic soil respiration is strongly and positively related to temperature. In the long-term its response to temperature is uncertain. One reason for this is because in field experiments increases in respiration due to warming are relatively short-lived. The explanations proposed for this ephemeral response include depletion of fast-cycling, soil carbon pools and thermal adaptation of microbial respiration. Using a 〉15 year soil warming experiment in a mid-latitude forest, we show that the apparent ‘acclimation’ of soil respiration at the ecosystem scale results from combined effects of reductions in soil carbon pools and microbial biomass, and thermal adaptation of microbial respiration. Mass specific respiration rates were lower when seasonal temperatures were higher, suggesting that rate reductions under experimental warming likely occurred through temperature-induced changes in the microbial community. Our results imply that stimulatory effects of global temperature rise on soil respiration rates may be lower than currently predicted.
    Description: This research was supported by the Office of Science (BER), U.S. Department of Energy and the Andrew W. Mellon Foundation.
    Keywords: Acclimation ; Adaptation ; Soil respiration ; Thermal biology ; Temperature ; Carbon cycling ; Climate change ; Climate warming ; Microbial community ; CO2
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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  • 3
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    Design and function of superfast muscles : new insights into the physiology of skeletal muscle (2005)
    Annual Reviews
    Details
    Publication Date: 2022-05-25
    Description: First published online as a Review in Advance on October 24, 2005. (Some corrections may occur before final publication online and in print)
    Description: Author Posting. © Annual Reviews, 2005. This article is posted here by permission of Annual Reviews for personal use, not for redistribution. The definitive version was published in Annual Review of Physiology 68 (2006): 22.1-22.29, doi:10.1146/annurev.physiol.68.040104.105418.
    Description: Superfast muscles of vertebrates power sound production. The fastest, the swimbladder muscle of toadfish, generates mechanical power at frequencies in excess of 200 Hz. To operate at these frequencies, the speed of relaxation has had to increase approximately 50-fold. This increase is accomplished by modifications of three kinetic traits: (a) a fast calcium transient due to extremely high concentration of sarcoplasmic reticulum (SR)-Ca2+ pumps and parvalbumin, (b) fast off-rate of Ca2+ from troponin C due to an alteration in troponin, and (c) fast cross-bridge detachment rate constant (g, 50 times faster than that in rabbit fast-twitch muscle) due to an alteration in myosin. Although these three modifications permit swimbladder muscle to generate mechanical work at high frequencies (where locomotor muscles cannot), it comes with a cost: The high g causes a large reduction in attached force-generating cross-bridges, making the swimbladder incapable of powering low-frequency locomotory movements. Hence the locomotory and sound-producing muscles have mutually exclusive designs.
    Description: This work was made possible by support from NIH grants AR38404 and AR46125 as well as the University of Pennsylvania Research Foundation.
    Keywords: Parvalbumin ; Ca2+ release ; Ca2+ uptake ; Cross-bridges ; Adaptation ; Sound production ; Whitman Center
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: 567086 bytes
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  • 4
    Electronic Resource
    Electronic Resource
    The bioenergetic coordination of a complex biological system is revealed by its adaptation to changing environmental conditions (1996)
    Springer
    Acta biotheoretica 44 (1996), S. 283-299 
    Details
    ISSN: 1572-8358
    Keywords: Adaptation ; Anacystis nidulans ; Cyanobacteria ; Flow-force relationship ; Growth ; Phosphate uptake ; Selforganization of aquatic ecosystems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The properties of the phosphate uptake system of the cyanobacterium Anacystis nidulans have been studied during the transition from a phosphate-deficient non-growing state to a non-deficient growing state. In the phosphate-deficient state the high affinity phosphate transport system in the cell membrane is extremely adaptive. As a result of these adaptive features the phosphate transport system cannot be described by determinate, fixed parameters, because the transport system is influenced by the measurement of the uptake process itself. When the growing state has been initiated by a persisting phosphate pulse, the transport system rapidly loses its adaptive features and can then be characterized by determinate parameters that remain unchanged for a long period of time, even if no uptake occurs in that time. Depending on the amount of phosphate stored during a pulse the cell makes a choice between slow or fast growth. In the latter case the light harvesting and energy converting machinery is completely reorganized before growth commences. Thereby the components of this machinery conform to each other and to the stable properties of the phosphate transport system. It is suggested that the mutual adjustment of these adaptive energy converting subunits is guided by attractors that function as the final cause for the development of the whole system. An application of this model to an analysis of the selforganization of aquatic ecosystems is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046534
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  • 5
    Electronic Resource
    Electronic Resource
    Bacteria tolerant to organic solvents (1998)
    Springer
    Extremophiles 2 (1998), S. 229-238 
    Details
    ISSN: 1433-4909
    Keywords: Key words Solvent-tolerant bacteria ; Adaptation ; Resistance ; Toxicity ; Log P ; Stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The toxic effects that organic solvents have on whole cells is an important drawback in the application of these solvents in environmental biotechnology and in the production of fine chemicals by whole-cell biotransformations. Hydrophobic organic solvents, such as toluene, are toxic for living organisms because they accumulate in and disrupt cell membranes. The toxicity of a compound correlates with the logarithm of its partition coefficient with octanol and water (log P ow). Substances with a log P ow value between 1 and 5 are, in general, toxic for whole cells. However, in recent years different bacterial strains have been isolated and characterized that can adapt to the presence of organic solvents. These strains grow in the presence of a second phase of solvents previously believed to be lethal. Different mechanisms contributing to the solvent tolerance of these strains have been found. Alterations in the composition of the cytoplasmic and outer membrane have been described. These adaptations suppress the effects of the solvents on the membrane stability or limit the rate of diffusion into the membrane. Furthermore, changes in the rate of the biosynthesis of the phospholipids were reported to accelerate repair processes. In addition to these adaptation mechanisms compensating the toxic effect of the organic solvents, mechanisms do exist that actively decrease the amount of the toxic solvent in the cells. An efflux system actively decreasing the amount of solvents in the cell has been described recently. We review here the current knowledge about exceptional strains that can grow in the presence of toxic solvents and the mechanisms responsible for their survival.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007920050065
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  • 6
    Electronic Resource
    Electronic Resource
    The prospects for an evolutionary psychology: Human language and human reasoning (1996)
    Springer
    Minds and machines 6 (1996), S. 541-557 
    Details
    ISSN: 1572-8641
    Keywords: Adaptation ; cognition ; evolutionary psychology ; human evolution ; language ; rationality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Philosophy
    Notes: Abstract Evolutionary psychology purports to explain human capacities as adaptations to an ancestral environment. A complete explanation of human language or human reasoning as adaptations depends on assessing an historical claim, that these capacities evolved under the pressure of natural selection and are prevalent because they provided systematic advantages to our ancestors. An outline of the character of the information needed in order to offer complete adaptation explanations is drawn from Robert Brandon (1990), and explanations offered for the evolution of language and reasoning within evolutionary psychology are evaluated. Pinker and Bloom's (1992) defense of human language as an adaptation for verbal communication, Robert Nozick's (1993) account of the evolutionary origin of rationality, and Cosmides and Tooby's (1992) explanation of human reasoning as an adaptation for social exchange, are discussed in light of what is known, and what is not known, about the history of human evolution. In each case, though a plausible case is made that these capacities are adaptations, there is not enough known to offer even a semblance of an explanation of the origin of these capacities. These explanations of the origin of human thought and language are simply speculations lacking the kind of detailed historical information required for an evolutionary explanation of an adaptation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00389658
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  • 7
    Electronic Resource
    Electronic Resource
    Resolution of pheromone pulses in receptor cells of Antheraea polyphemus at different temperatures (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 301-310 
    Details
    ISSN: 1432-1351
    Keywords: Pheromone receptor cells ; Single sensillum recording ; Temperature dependence ; Nerve-impulse response ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The ability of pheromone receptor cells of male Antheraea polyphemus (Saturniidae) to resolve stimulus pulses was determined at different temperatures (8°, 18°, 28°C). The cells were stimulated by repeated 20-ms puffs of the pheromone components (E, Z)-6, 11-hexadecadienyl acetate and (E, Z)-6,11-hexadecadienal. At higher temperatures, higher frequencies of stimulus pulses were resolved by the nerve-impulse response: about 1.25 pulses per second at 8°C, 2.5 pulses/s at 18°C and 5 pulses/s at 28°C. The decreased ability of receptor cells to resolve stimulus pulses at low temperatures may reduce the male moth's chance of reaching the pheromone source. The peak nerve-impulse frequency increased whereas the duration of nerve-impulse responses to single stimulus pulses decreased at higher temperatures. At a given temperature and stimulus intensity the peak nerveimpulse frequency decreased with shorter intervals between the stimulus pulses, but the duration of the responses remained almost constant. The time needed for recovery from adaptation caused by a single stimulus pulse was longer at lower temperatures. The aldehyde receptor cell recovered more quickly than the acetate cell. At low stimulus concentration, the resolution ability of the acetate cell was strongly decreased, whereas in the aldehyde cell it was only slightly impaired.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194984
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  • 8
    Electronic Resource
    Electronic Resource
    Song recognition in the grasshopper Chorthippus biguttulus is not impaired by shortening song signals: implications for neuronal encoding (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 729-735 
    Details
    ISSN: 1432-1351
    Keywords: Key words Grasshoppers ; Acoustic communication ; Neuronal encoding ; Adaptation ; Neuronal reliability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The communication signals in many grasshopper species are composed of multiple repetitions of highly stereotyped subunits, and thus provide redundancy. In a behavioural paradigm, we tested the ability of males of the grasshopper Chorthippus biguttulus to recognize shortened versions of the communication signals of conspecific females. Males reliably responded to a three-subunits signal (250 ms), i.e. to a signal of less than a quarter of the natural duration. This performance is remarkable in view of the substantial adaptation and the variability present in the spiking responses of auditory interneurones. These behavioural results will impose constraints for investigating possible encoding mechanisms used by the grasshoppers' auditory system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050295
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  • 9
    Electronic Resource
    Electronic Resource
    Chemosensory responses of Tetrahymena thermophila to CB2, a 24-amino-acid fragment of lysozyme (1999)
    Springer
    Journal of comparative physiology 184 (1999), S. 529-534 
    Details
    ISSN: 1432-1351
    Keywords: Key words Chemorepellent ; Chemosensory transduction ; Receptor potential ; Adaptation ; Receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract While lysozyme is a depolarizing chemorepellent in Tetrahymena, the entire lysozyme molecule is not necessary to activate the lysozyme receptor. Reduced lysozyme was cut into three fragments by cyanogen bromide cleavage and the fragments (CB1, CB2 and CB3) were separated by HPLC. Behavioral bioassays showed that the carboxy-terminal 24-amino-acid fragment, which we call CB2, is 100 times more active than intact lysozyme as a chemorepellent. CB2 appears to activate the same receptor as lysozyme because behavioral cross-adaptation is seen between these two compounds and an antibody generated to the purified lysozyme receptor blocks responses to both lysozyme and CB2. This is further supported by the observation that neomycin, which is a competitive inhibitor of lysozyme binding, also inhibits CB2 responses. This inhibition may be due to the fact that neomycin is highly positively charged (+5 at pH 7.0) and CB2 has a net charge of +4 at pH 7.0. Intracellular electrophysiological recordings documented that CB2 elicits a transient, depolarizing receptor potential that is similar to the lysozyme-induced depolarizations except they are much smaller. CB2 is a more potent and specific ligand for use in studies of the lysozyme receptor of Tetrahymena.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050352
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  • 10
    Electronic Resource
    Electronic Resource
    Time course of color induction in the honeybee (1995)
    Springer
    Journal of comparative physiology 177 (1995), S. 207-217 
    Details
    ISSN: 1432-1351
    Keywords: Honeybee ; Color vision ; Behavior ; Adaptation ; Color induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Color induction in the honeybee is investigated in color discrimination experiments. An individual bee walks in a dark arena and is trained to a self-luminant stimulus presented from below. In the dual-choice tests the dark background is replaced by a colored induction stimulus. Choice behavior is recorded by TV camera and analyzed by computer. Successive color induction is separated from simultaneous induction by analysis of the walking paths. Only successive color induction occurs. Simultaneous effects are not observed. That is a stimulus acts as a color inducing stimulus only when the bee crosses this stimulus. Thus, the color perceived by a given eye region is found to be dependent on the viewing history, but not on the stimuli presented simultaneously on neighboring parts of the retina. Color induction in the honeybee described in terms of selective sensitivity decrease (adaptation) does not explain all behavioral effects induced by the stimulus. The time course of successive color induction is calculated from the exposure times to the induction stimulus and from the choice behavior. The data suggest that color induction is complete after a few seconds. Photoreceptor adaptation is sufficient to explain the observed time course.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225100
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  • 11
    Electronic Resource
    Electronic Resource
    Regulation of sex-specific feeding behavior in fiddler crabs: physiological properties of chemoreceptor neurons in claws and legs of males and females (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 513-526 
    Details
    ISSN: 1432-1351
    Keywords: Adaptation ; Chemosensation ; Crustacea ; Disadaptation ; Sexual dimorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This study examined properties of chemoreceptor neurons in the claws and legs of the fiddler crabs Uca pugilator and U. pugnax. The primary goal was to establish the neural basis of previously observed greater female sensitivity to feeding stimulants, and secondarily to compare physiological properties of chemoreceptor neurons in these semi-terrestrial crustaceans with those of fully aquatic forms. Sensitivity of chemoreceptor neurons in claws and legs is sex-specific; individual neurons of females respond to lower stimulus concentrations than male chemoreceptor neurons, and equivalent concentrations elicit greater spiking in female vs male chemoreceptor neurons. Thus, the population of chemoreceptor neurons in females expresses lower thresholds and greater average sensitivity than in males. Greater sensitivity of claw neurons explains observations indicating that females continue to feed at food levels too low to stimulate males. Sensitivity differences in leg neurons of males vs females have no clear behavioral correlate, but suggest that females can orient to more dilute stimuli than males. Chemoreceptor neurons of fiddler crabs have low sensitivities and slow rates of adaptation compared to other crustaceans. Also, neurons in claws adapt less slowly than neurons in legs, which may reflect subtle differences in the chemical stimulus environment experienced by claws vs legs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196417
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  • 12
    Electronic Resource
    Electronic Resource
    Location and dynamic properties of the spike generator in an insect mechanosensory neuron (1996)
    Springer
    Journal of comparative physiology 179 (1996), S. 235-243 
    Details
    ISSN: 1432-1351
    Keywords: Adaptation ; Insect ; Dendrite ; Encoding ; Mechanoreceptor ; Power law
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1.The cereal bristle hairs of the cockroach, Periplaneta americana, are each innervated by one mechanosensory cell and 1–5 chemosensory cells. In transepithelial recordings, chemo- and mechanosensory spikes could be discriminated from each other by their relative amplitude. 2. When current steps were applied via the sensory hair, trains of impulses were triggered whatever the polarity of the current. 3. All responses adapted to the current, but the time course of adaptation was fitted by a power law for outward currents and an exponential law for inward currents. 4. During application of outward currents, the spikes showed a negative initial phase on which a small positive component was superimposed; strong polarizations produced purely negative spikes. More classical spikes with a positive initial phase were induced by inward currents. 5. The present work supports the hypothesis of a direct excitability of the apical dendrite in cereal bristle mechanoreceptors and confirms previous results suggesting that spikes are normally triggered within that region during mechanical stimulations. It is also established, for the first time, that adaptation to currents may be different in the apical dendrite and in more basal regions of the same mechanosensory neuron.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00222790
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  • 13
    Electronic Resource
    Electronic Resource
    A quantitative model of successive color induction in the honeybee (1995)
    Springer
    Journal of comparative physiology 177 (1995), S. 219-234 
    Details
    ISSN: 1432-1351
    Keywords: Color vision ; Honeybee ; Behavior ; Adaptation ; Lateral filtering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Intensity discrimination experiments are performed with individual walking honeybees trained to color stimuli (UV, blue and green) of constant intensity. The choice behavior to stimuli of identical wavelength spectrum but different intensities is tested. A graded choice behavior is found. The training intensity is chosen with the highest probability in most cases. Phototaxis as well as brightness discrimination can be excluded. The choice behavior is explained exclusively by discrimination of chromaticness (hue and saturation) according to the Bezold-Brücke shift. The bees adapt to the chromatic stimuli during their choices. From the behavioral data, it is concluded that in adaptation, adjustment in photoreceptor sensitivity in one receptor also affects the sensitivity of the other receptors (“co-adaptation”). The linear adaptation model corresponding to the von Kries Coefficient Law used up to now to describe adaptation to white light in the honeybee does not describe this type of adaptation. A quantitative model of adaptation to chromatic stimuli extending the linear adaptation model is developed. The most reasonable mechanism of co-adaptation is optical coupling by lateral filtering. Other mechanisms such as electrical coupling are unlikely, since their effects on color vision would lead to effects inconsistent with Graßmann's Laws.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225101
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  • 14
    Electronic Resource
    Electronic Resource
    Can strains give adequate information for adaptive bone remodeling? (1984)
    Springer
    Calcified tissue international 36 (1984), S. S118 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Strain ; Remodeling ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary For bone to remodel adaptively, the cells responsible should follow some algorithm. Nine different loading situations and structures are discussed. It seems that either algorithm must be extremely complex, or cells in different structures must follow different algorithms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02406144
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  • 15
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    Plasticity or fixed adaptive traits? Strategies for predation avoidance in Rana arvalis tadpoles (1998)
    Springer
    Oecologia 117 (1998), S. 119-126 
    Details
    ISSN: 1432-1939
    Keywords: Key words Amphibians ; Predation ; Plasticity ; Adaptation ; Life history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tadpoles of Rana arvalis originating from seven island populations were tested for responses to non-lethal predator presence. In general, tadpole growth was reduced and the relative tail depth was increased at predator presence. There was no effect of predator presence on the predicted size at metamorphosis. The differentiation rate, translating as length of the larval period, was lower at predator presence, but this seems to be merely an effect of the reduced growth. Although populations differed with respect to growth, relative tail length, relative tail depth, differentiation rate and predicted size at metamorphosis, no obvious differences were found in their responses to predator presence. Data on predator occurrences in the source ponds show that tadpoles originating from ponds with a high predation pressure have a higher differentiation rate, i.e. they will metamorphose at an earlier date than those from “safe” ponds (if raised under the same conditions). Moreover, they are also predicted to metamorphose at a smaller size, which is in accordance with theoretical models. Despite the fact that populations differed in growth, no correlation was found between growth and predation risk in the source ponds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050639
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  • 16
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    Life history patterns in female moose (Alces alces): the relationship between age, body size, fecundity and environmental conditions (1996)
    Springer
    Oecologia 106 (1996), S. 212-220 
    Details
    ISSN: 1432-1939
    Keywords: Fecundity ; Body size ; Climate ; Survival ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I examined the relationship between age, body size and fecundity in 833 female moose (Alces alces) from 14 populations in Sweden sampled during 1989–1992. Data on population density, food availability and climatic conditions were also collected for each population. Age and body mass were both significantly positively related to fecundity, measured as ovulation rate, among female moose. The relationship between the probability of ovulation and body mass was dependent on age with (1) a higher body mass needed in younger females for attaining a given fecundity, and (2) body mass having a stronger effect on fecundity in yearling (1.5 year) than in older (≥2.5 year) females. Thus, a 40 kg increase in yearling body mass resulted in a 42% increase in the probability of ovulation as compared to a 6% increase in older females. The lower reproductive effort per unit body mass, and the relatively stronger association between fecundity and body mass in young female moose compared to older ones, is likely to primarily represent a mechanism that trades off early maturation against further growth, indicating a higher cost of reproduction in young animals. In addition to age and body mass, population identity explained a significant amount of the individual variation in fecundity, showing that the relationship between body mass and fecundity was variable among populations. This variation was in turn related to the environment, in terms of climatic conditions forcing female moose living in relatively harsh/more seasonal climatic conditions to attain a 22% higher body mass to achive the same probability of multiple ovulation (twinning) as females living in climatically milder/less seasonal environments. The results suggests that the lower fecundity per unit body mass in female moose living in climatically harsh/more seasonal environments may be an adaptive response to lower rates of juvenile survival, compared to females experiencing relatively milder/less seasonal climatic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328601
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  • 17
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    The correlation of the receptor potential with the light induced transient increase in intracellular calcium-concentration measured by absorption change of arsenazo III injected into Limulus ventral nerve photoreceptor cell (1980)
    Springer
    European biophysics journal 6 (1980), S. 191-208 
    Details
    ISSN: 1432-1017
    Keywords: Receptor potential ; Intracellular and extracellular calcium concentration ; Intensity dependence ; Adaptation ; Sensitivity control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The light-induced membrane voltage response (receptor potential, ReP) and the absorption change of the intracellularly injected calcium indicator arsenazo III (arsenazo response) were recorded simultaneously in Limulus ventral nerve photoreceptor cells. A double pulse technique was applied for stimulation. After pressure injection of the indicator into the cell absorption changes were measured at 646 nm to obtain a measure of the changes of the intracellular calcium ion concentration. 1. The size of the arsenazo response increases with increasing intensity of the light stimulus. The intensity dependence of the size of the arsenazo response δAmax shows almost no correlate with the peak amplitude of the ReP, but correlates rather well with the time integral of the ReP. 2. Decreasing light adaptation (caused by prolongation of the repetition time of the pulse pairs) leads to an increase in size of the arsenazo response. Also here δAmax correlates better with the time integral of the ReP than with its peak amplitude. 3. Lowering the calcium concentration in the superfusate (from 10 mmol/l to ca. 40 Μmol/l) causes after ca. 10 min a drastical diminution of the arsenazo response to values below the noise level, and a less marked reduction in size of the ReP. The falling phase of the ReP is slower. After return to normal calcium concentration the arsenazo response recovers partly in ca. 50 min, while the ReP recovers faster. The results show two opposite correlations between ReP and arsenazo response: Increase in size and duration of the ReP causes a greater transient increase of the intracellular calcium ion concentration. This in turn tends to reduce and shorten the ReP. Which effect dominates obviously depends on the conditions of the experiment: when the calcium concentration in the superfusate is reduced to ca. 40 Μmol/l a slow decrease of the ReP is accompanied by a small increase of the intracellular calcium ion concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00537293
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  • 18
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    Adaptation properties of the ERG in the grasshopper, Romalea microptera (1981)
    Springer
    European biophysics journal 7 (1981), S. 205-208 
    Details
    ISSN: 1432-1017
    Keywords: Grasshopper ; Electroretinogram ; Adaptation ; Spectral sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The grasshopper ERG displays a rapid recovery of responsivity following the onset of a background light. Although observed earlier in skate and frog, this phenomenon has not previously been seen in an invertebrate. Furthermore, a period of hyperresponsivity exists in early dark adaptation and resembles that found in skate and frog. Thus, recovery in the light and hyperresponsivity in the dark seem to be corollaries of each other. Finally, spectral sensitivity of the ERG is determined and two peaks are found: one at 510 nm and the other at 360 nm. The former appears to be a rhodopsin-mediated sensitivity but the latter does not and they are not clearly separated by chromatic adaptation.
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    The contribution of pigment transitions to sensitivity changes in the barnacle photoreceptor and the correlation with the prolonged depolarizing afterpotential (1982)
    Springer
    European biophysics journal 8 (1982), S. 161-172 
    Details
    ISSN: 1432-1017
    Keywords: Photoreceptor ; Visual pigment ; Adaptation ; Facilitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A conditioning light can cause a decrease (adaptation) or an increase (facilitation) in the sensitivity of barnacle photoreceptors, as measured by the amplitude of the late receptor potential (LRP). We show that a net transfer of visual pigment from the rhodopsin (R) to the metarhodopsin (M) state induces a large facilitation whereas the reverse transfer results in a much smaller facilitation or even an adaptation. These effects were not due to the response to the conditioning light but to the pigment reactions. When the conditioning light did not alter the pigment population (i.e., M → M, R → R) it was followed by an intermediate degree of facilitation. These conclusions are correct for cells which have relatively low sensitivity. In sensitive cells, all pigment transitions produce adaptation. LRP facilitation and the prolonged depolarizing afterpotential (PDA) show several common characteristics with respect to pigment transitions: 1.Their magnitude increases with the amount of pigment transferred from R to M. 2. Both are depressed by the M → R transition. 3. Their production is impeded by the M → R transition. 4. The PDA itself is facilitated by the R → M transition and this facilitation decays with a time course comparable to that of LRP facilitation. These results suggest that there may be an underlying process common to LRP facilitation and PDA.
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    Sensitivity changes of photoreceptor cells of Hirudo medicinalis caused by changes in extracellular calcium concentration (1982)
    Springer
    European biophysics journal 8 (1982), S. 173-187 
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    ISSN: 1432-1017
    Keywords: Leech photoreceptors ; Extracellular calcium ; Excitation ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Extracellular recordings from the vacoule of photoreceptor cells of Hirudo medicinalis L. were performed using microelectrodes. The cells were adapted by white light flashes given at constant intervals (20 s). Response height versus relative intensity curves obtained from the same cell in physiological saline (PS) and in bathing solutions of either a) lowered calcium contents (2 ΜM/1 or less) or b) raised calcium contents (15 mM/1) were compared. The cells' adaptation state in PS was operationally defined by the ratio Q=h A /h S where h A is the response height evoked by the adapting flashes, and h S is the corresponding saturation response height. Sensitivity changes were measured by the half saturation intensity shift. Lowering extracellular calcium resulted in: 1. The response height increased and the shape of the response became more rounded and prolonged. 2. The total resistance between the vacuole and outside decreased from 8.2±1.4 MΩ (n=6) in PS to 4.6±0.4 MΩ (n=5). The resistance was independent of the cells' adaptation state. 3. A change of the cells' sensitivity occured either in direction to light adaptation or in direction to dark adaptation. It depended functionally on the ratio Q: a) if Q was less or equal to about 0.6 the cells' sensitivity increased. b) if Q was greater than 0.6 the cells' sensitivity diminished. Raising extracellular calcium decreased the sensitivity of all cells tested independent of their adaptation states in PS. The results can be interpreted under the assumptions that 1. the sensitivity of leech photoreceptor cells is inversely proportional to the intracellular free calcium concentration and Z. intracellular calcium can interact with extracellular calcium in relatively dark adapted cells whereas in relatively light adapted cells the raise of intracellular free calcium is mainly effected by a release from intracellular stores. It is assumed that a Q value of about 0.6 separates relatively light adapted cells from relatively dark adapted cells.
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    The vhuU gene encoding a small subunit of a selenium-containing [NiFe]-hydrogenase in Methanococcus voltae appears to be essential for the cell (1998)
    Springer
    Archives of microbiology 170 (1998), S. 418-426 
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    ISSN: 1432-072X
    Keywords: Key words Archaea ; Methanococcus voltae ; Deletion ; mutagenesis ; Adaptation ; Selenium deprivation ; [NiFe]-hydrogenases ; Gene replacement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We developed a general method for the site-specific deletion of gene sequences to obtain new selectable markers in the archaeon Methanococcus voltae. Using a deletion in the hisA gene, a vector was integrated into the chromosome by homologous recombination, thereby reconstituting histidine prototrophy. The vector contained the β-glucuronidase gene uidA of Escherichia coli as a reporter under the control of an M. voltae promoter that normally drives the expression of a selenium-free [NiFe]-hydrogenase after selenium deprivation. This construct has allowed us to check whether the selenium supply was sufficiently low to induce the transcription of the genes encoding the selenium-free hydrogenases. We tried to introduce a chromosomal deletion of the vhuU gene of the archaeon M. voltae by gene replacement and by keeping the cells under selenium deprivation. The gene vhuU encodes the very small, selenocysteine-containing subunit that is part of the primary reaction center of the Vhu hydrogenase. All transformants bearing the deletion also contained the vhuU wild-type gene. Therefore, the vhuU gene appears to be essential for the cell even under conditions that lead to the induction of the selenium-free homologue Vhc of the Vhu hydrogenase.
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    Growth of bacteria at 100°C and beyond (1981)
    Springer
    Archives of microbiology 129 (1981), S. 127-128 
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    ISSN: 1432-072X
    Keywords: Continuous culture ; Adaptation ; Simulation of hot springs ; Boiling point ; Caldoactive bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacillus caldolyticus, a caldoactive bacterium originating from a hot spring at Yellowstone Park, was grown in a defined medium, whose composition resembled that of the pool water. Using a chemostat culture, which simulated the natural conditions, the organism could be adapted to grow at 100°C at a reasonable rate. Under increased pressure growth occurred also at 105° C.
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    Properties of enzymes from bacteria grown in the 70–100°C range (1981)
    Springer
    Archives of microbiology 130 (1981), S. 159-164 
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    ISSN: 1432-072X
    Keywords: Adaptation ; Boiling point ; Caldoactive enzymes ; Stabilization ; Thermostability ; Thermal characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In chemostat cultures of Bacillus caldolyticus, adaptation in a single step from 70–100°C was followed under aerobic and oxygen-limited conditions and was found to proceed more smoothly under the latter circumstances. Variations of the medium (e.g. yeast extract or silicate concentrations) showed that growth at 100°C is in all respects similar to that of cultures at moderate temperatures. Enzyme preparations derived from cultures at 5°C intervals between 70 and 100°C were used to determine the temperature range. For all nine enzymes tested, the optimum temperature was found to be 67°C; the latter was independent of the growth temperature. Differences were found, however, with respect to the maximum temperature of individual enzymes, and three groups, with maxima between 70 and 80°C, 80 and 90°C and 90 and 100°C can be distinguished. Again, there was no correlation with the growth temperature. Stability experiments also revealed that enzymes from the same organism can have different thermal properties: Some were found to be quite thermolabile (e.g. the pyruvate kinase), while others (e.g. hexokinase and glutamate-pyruvate transaminase) exhibited a high thermostability. These properties were not related to the growth temperature within the 70–100°C range, too. Six of the enzymes tested could be stabilized by their respective substrates, but the degree of protection varied for individual enzymes. Three enzymes (acetate kinase, glutamate dehydrogenase and myokinase) could not be stabilized by their substrates. Comparative experiments with the hexokinase suggested, that the thermal integrity of the enzymes is better protected within the cell as compared to the stability of the enzyme preparations.
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    Effects of sodium chloride on the plasma membrane of halotolerant Dunaliella primolecta: an electron spin resonance study (1982)
    Springer
    Archives of microbiology 131 (1982), S. 184-190 
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    ISSN: 1432-072X
    Keywords: Dunaliella primolecta ; Malotolerant ; Adaptation ; Plasma membrane ; ESR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Electron spin resonance spectroscopy was used to monitor the in vivo microviscosity of the plasma membrane and lipid extracts of the salt tolerant alga, Dunaliella primolecta. The fluidity of the plasma membrane decreased as the algae were adapted to and suspended in higher sodium chloride concentrations [2–24% (w/v)]. Both biochemical modification and a physical interaction between Na+ and lipids were implicated. When the microviscosity of the plasma membrane and that of lipid extracts were determined as a function of temperature, two or three lipid phase transformations were observed. There were always transformations at 9–14° C and 39–43° C. These were interpreted as the onset and completion of the lipid phase transition of at least a major lipid component of the membrane, possibly the entire membrane. These transformation temperatures were independent of the salt concentration to which the algae were adapted or suspended. This suggests that D. primolecta exists with some of its membrane in the solid-fluid mixed lipid state. With a NaCl concentration of 8% (w/v) or greater in the growth medium, a third transformation occurred around 20–22° C. It was the result of a lipid-lipid interaction and was not related to adaptation.
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    Photosensory transduction in the flagellated alga, Euglena gracilis (1983)
    Springer
    Archives of microbiology 134 (1983), S. 204-207 
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    ISSN: 1432-072X
    Keywords: Photosensory ; Cations ; pH ; Flagellated ; Algae ; Adaptation ; Euglena gracilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Euglena were cultured under 3 W m-2 constant white light. In culture medium, cells show immediate and long lasting step-down photophobic responses and photoaccumulation behavior to blue light if dim red light-adapted for 30 min. However, if cells are suspended in buffered, saltcontaining solutions (adaptation buffers), strong step-down photobehavior and photoaccumulation responses are not observed for several hours. These behaviors gradually increase in strength to reach a maximum after 6–12 h; after which a stable response is maintained. The relative rates of appearance and the relative strengths of the responses are influenced by the concentrations of Ca2+ and K+, but not H+ or Na+ ions, in the adaptation buffers. Expression of the stepdown photobehavior thus requires that the cells adapt to the chemical environment in which they are suspended.
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    Conversion of energy in halobacteria: ATP synthesis and phototaxis (1996)
    Springer
    Archives of microbiology 166 (1996), S. 1-11 
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    ISSN: 1432-072X
    Keywords: Key words Archaea ; Halobacteria ; Energy ; transduction ; Retinal protein ; Proton gradient ; Nitrate ; reductase ; ATPase ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Halobacteria are aerobic chemo-organotroph archaea that grow optimally between pH 8 and 9 using a wide range of carbon sources. These archaea have developed alternative processes of energy provision for conditions of high cell densities and the reduced solubility of molecular oxygen in concentrated brines. The halobacteria can switch to anaerobic metabolism by using an alternative final acceptor in the respiratory chain or by fermentation, or alternatively, they can employ photophosphorylation. Light energy is converted by several retinal-containing membrane proteins that, in addition to generating a proton gradient across the cell membrane, also make phototaxis possible in order to approach optimal light conditions. The structural and functional features of ATP synthesis in archaea are discussed, and similarities to F-ATPases (functional aspects) or vacuolar ATPases (structural aspects) are presented.
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    Ultra-violet mutagenesis of Synechocystis sp. 6701: mutations in chromatic adaptation and phycobilisome assembly (1984)
    Springer
    Archives of microbiology 138 (1984), S. 237-243 
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    ISSN: 1432-072X
    Keywords: Cyanobacteria ; Synechocystis 6701 ; Phycobilisomes ; Ultra-violet ; Mutagenesis ; Assembly ; Chromatic ; Adaptation ; Rods ; Cores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Mutations affecting pigmentation of the cyanobacterium Synechocystis sp. 6701 were induced with ultraviolet light. Two mutants with phycobilisome structural changes were selected for structural studies. One mutant, UV08, was defective in chromatic adaptation and incorporated phycoerythrin into phycobilisomes in white or red light at a level typical of growth in green light. The other mutant, UV16, was defective in phycobilisome assembly: little phycocyanin was made and none was attached to the phycobilisome cores. The cores were completely free of any rod substructures and contained the major core peptides plus the 27,000 Mr linker peptide that attaches rods to the core. Micrographs of the core particles established their structural details. Phycoerythrin in UV 16 was assembled into rod structures that were not associated with core material or phycocyanin. The 30,500 Mr and 31,500 Mr linker peptides were present in the phycoerythrin rods with the 30,500 Mr protein as the major component. Phycobilisome assembly in vivo is discussed in light of this unusual mutant.
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    Theoretical considerations on growth kinetics and physiological adaptation of nutrient-limited phytoplankton (1984)
    Springer
    Archives of microbiology 140 (1984), S. 96-100 
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    ISSN: 1432-072X
    Keywords: Physiology ; Adaptation ; Growth ; Droop ; Monod
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In many experimental ecological studies on phytoplankton species the growth response of an organism to the prevailing environmental conditions have been studied. Curves relating specific growth rate (μ) to the external nutrient concentration (S) have been constructed to compare nutrient-limited growth of different species under steady state conditions. Microorganisms adapt their physiology to a certain limitation in order to optimize growth. Therefore the shape of the μ/S curve is closely related to the way a micoorganism adapts its physiology. To see how physiological adaptation and growth rate are interconnected to each other, both can be related to the internal concentration of the growth-limiting nutrient. How the growth rate is related to the internal nutrient concentration is presented in a mathematical equation. Many phytoplankton species during growth under different nutrient limitations show a linear relationship between μ and the reciprocal value of the internal nutrient content (= Yield). This was originally observed by Droop. The model presented here gives a theoretical explanation of this phenomenon.
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    Factor biases and promoting sustainable development: Adaptation to drought in the Senegal River Basin (1996)
    Springer
    Mitigation and adaptation strategies for global change 1 (1996), S. 139-165 
    Details
    ISSN: 1573-1596
    Keywords: Adaptation ; agriculture ; agroforestry ; climate change ; drought ; ecological degradation ; factor bias ; Senegal ; sustainability ; social relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Abstract The ongoing drought in the Sahel region of West Africa highlights the vulnerability of food-producing systems to climate change and variability. Adaptation to climate should therefore increase the sustainability of agriculture under a long-term drought. Progress towards sustainability and adaptation in the the Senegal River Basin is hampered by an existing set of social and ecological relationships that define the control over the means of production and how people interact with their environment. These relationships are sensitive to the technological inputs and the administration of food production, or the factor bias in the different policy alternatives for rural development. One option is based on state-controlled, irrigated plantations to provide rice (Oryza) for the capital, Dakar. This policy emphasizes a top-down management approach, mechanized agriculture and a reliance on external inputs which strengthens the relationships introduced during the colonial period. A time series decomposition of the annual flow in the Senegal River at Bakel in Senegal suggests that water resources availability has been substantially curtailed since 1960, and a review of the water resources budget or availability in the basin suggests that this policy's food production system is not sustainable under the current climate of the basin. Under these conditions, this program is exacerbating existing problems of landscape degradation and desertification, which increases rural poverty. A natural resource management policy offers two adaptation strategies that favour decentralized management and a reduction of external inputs. The first alternative, “Les Perimetres Irrigués”, emphasizes village-scale irrigation, low water consumption cereal crops and traditional socio-political structures. The second alternative emphasizes farm-level irrigation and agro-forestry projects to redress the primary effects of desertification. The water requirements of both the rice import substitution program and the natural resource management program are calculated. A water resources simulation model/optimization analysis using dynamic programming is used to compare these two alternatives to the rice import substitution programs. Results indicate that the natural resource management policy could potentially bring a large area into production while using far less water than the rice import substitution program. The natural resource management policy, in particular the second alternative with its emphasis on individual ownership and ecological rehabiliation, defines a different set of social and ecological relationships that appear to enhance the sustainability of food production under a long-term drought.
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    Information about previous phosphate fluctuations is stored via an adaptive response of the high-affinity phosphate uptake system of the cyanobacterium Anacystis nidulans (1995)
    Springer
    Planta 197 (1995), S. 147-155 
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    ISSN: 1432-2048
    Keywords: Adaptation ; Anacystis ; Cyanobacterium ; Information storage ; Phosphate uptake system ; Threshold concentration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The high-affinity uptake system of phosphatelimited cyanobacterium Anacystis nidulans [Synechococcus leopoliensis (Raciborski) Komarek] is characterized by a threshold value below which uptake cannot occur. Here it is shown that, if phosphate-limited cyanobacteria are challenged with a short pulse of high phosphate concentration that appreciably exceeds this threshold value, the uptake system undergoes an adaptive response, leading to the attainment of new kinetic properties and a new threshold value. These new properties are maintained for several hours after the pulse. A notable characteristic of this new state is a wide linear dependence of the uptake rate on the external phosphate potential that is a function of the driving force of the uptake process. According to theoretical arguments it is shown that this “linear operation mode” can be explained by the simultaneous operation of several uptake systems with different, staggered threshold values and kinetic properties. Moreover, the new linear uptake properties, in turn, reflect the prehistory of phosphate supply experienced by the population. The consequences of this result with regard to environmental fluctuations of the phosphate concentration in lakes are discussed.
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    Darwinian adaptation, population genetics and the streetcar theory of evolution (1996)
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    Journal of mathematical biology 34 (1996), S. 511-532 
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    ISSN: 1432-1416
    Keywords: Adaptation ; Optimality ; Nash equilibrium ; ESS ; N-locus genetics ; Epistasis ; Long-term evolution ; Rationality paradox
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract This paper investigates the problem of how to conceive a robust theory of phenotypic adaptation in non-trivial models of evolutionary biology. A particular effort is made to develop a foundation of this theory in the context ofn-locus population genetics. Therefore, the evolution of phenotypic traits is considered that are coded for by more than one gene. The potential for epistatic gene interactions is not a priori excluded. Furthermore, emphasis is laid on the intricacies of frequency-dependent selection. It is first discussed how strongly the scope for phenotypic adaptation is restricted by the complex nature of ‘reproduction mechanics’ in sexually reproducing diploid populations. This discussion shows that one can easily lose the traces of Darwinsm inn-locus models of population genetics. In order to retrieve these traces, the outline of a new theory is given that I call ‘streetcar theory of evolution’. This theory is based on the same models that geneticists have used in order to demonstrate substantial problems with the ‘adaptationist programme’. However, these models are now analyzed differently by including thoughts about the evolutionary removal of genetic constraints. This requires consideration of a sufficiently wide range of potential mutant alleles and careful examination of what to consider as a stable state of the evolutionary process. A particular notion of stability is introduced in order to describe population states that are phenotypically stable against the effects of all mutant alleles that are to be expected in the long-run. Surprisingly, a long-term stable state can be characterized at the phenotypic level as a fitness maximum, a Nash equilibrium or an ESS. The paper presents these mathematical results and discusses — at unusual length for a mathematical journal — their fundamental role in our current understanding of evolution.
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    Adaptation of sorghum: characterisation of genotypic flowering responses to temperature and photoperiod (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 900-911 
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    ISSN: 1432-2242
    Keywords: Key words Sorghum bicolor ; Flowering ; Temperature ; Photoperiod ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sorghum [Sorghum bicolor (L.) Moench] is an important cereal crop grown in a wide range of tropical and temperate environments. This study was conducted to characterise the photothermal flowering responses of sorghum genotypes and to examine relationships between photothermal characteristics and environment of origin in order to better understand the phenological basis of adaptation to environment in sorghum. Twenty-four germplasm accessions and one hybrid from 24 major sorghum-growing areas were grown in a wide range of environments varying in temperature and photoperiod in India, Kenya and Mali between 1992 and 1995. Times from sowing to flowering (f) were recorded, and the responsiveness of 1/f to temperature and photoperiod was quantified using photothermal models. Times from sowing to flowering were accurately predicted in a wide range of environments using a multiplicative rate photothermal model. Significant variation in the minimum time to flower (Fm) and photoperiod sensitivity (critical photoperiod, Pc, and photoperiod-sensitivity slope, Ps) was observed among the genotypes; in contrast there was little variation in base temperature (Tb). Adaptation of sorghum to the diverse environments in which it is grown was largely determined by photoperiod sensitivity and minimum time to flower; photoperiod sensitivity determines broad adaptation to latitude (daylength), while variation in the minimum time to flower determines specific adaptation within smaller ranges of latitude, e.g. within the humid and sub-humid tropics.
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    Several QTLs involved in osmotic-adjustment trait variation in barley (Hordeum vulgare L.) (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 688-698 
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    ISSN: 1432-2242
    Keywords: Key words Water stress ; Barley ; Osmotic adjustment ; Adaptation ; QTL ; Synteny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Osmotic adjustment (OA) was previously demonstrated to be an important adaptive mechanism of drought tolerance in cereals. In order to determine which genomic regions are involved in OA variation, 187 barley (Hordeum vulgare L.) recombinant inbred lines (RILs) derived from a cross between Tadmor (drought tolerant) and Er/Apm (susceptible) were studied in a growth chamber for their OA capacity (through correlated traits and by calculation), at an early growth stage and under two water treatments (soil moisture of 14% and 100% of field capacity). The continuous distribution of the traits and their broad-sense line heritabilities, ranging from 0.04 to 0.44, indicated that OA and related traits should have a polygenic nature. A subset of 167 RILs were also genotyped using 78 RFLP, 32 RAPD and three morphological markers and a linkage map was constructed. Despite strong environmental effects acting on the traits, interval mapping and single-marker ANOVA allowed the detection of three QTLs for relative water content (RWC), four QTLs for osmotic potential (ψπ), two QTLs of osmotic potential at full turgor (ψπ100) and one QTL for osmotic adjustment at a soil moisture of 14% field capacity. For the irrigated treatment, only two QTLs were detected: one for RWC and one for ψπ100. Two chromosomal regions were involved in several OA-related trait variations and could be considered as regions controlling OA; these were present on chromosome 1 (7H) and chromosome 6 (6H), whereas other regions were specific for one trait. No major QTL was found. However, the genomic region involved in OA-related traits on chromosome 1 (7H) in barley seemed to be conserved for OA variation among cereals. Epistatic effects, with or without additive effects, acted on the traits.
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    Genetic analysis of adaptation differences between highland and lowland tropical maize using molecular markers (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 1106-1119 
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    ISSN: 1432-2242
    Keywords: Key words Maize ; Adaptation ; Tropical ; Highland and lowland ; QTL mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Molecular-marker loci were used to investigate the adaptation differences between highland and lowland tropical maize. An F2 population from the cross of two inbred lines independently derived from highland and lowland maize germplasm was developed, and extracted F3:4 lines were phenotype in replicated field trials at four thermally diverse tropical testing sites, ranging from lowland to extreme highland (mean growing season temperature range 13.2–24.6°C). Traits closely related with adaptation, such as biomass and grain yield, yield components, days from sowing to male and female flowering, total leaf number, plant height and number of primary tassel branches (TBN), were analyzed. A large line × environment interaction was observed for most traits. The genetic basis of this interaction was reflected by significant, but systematic, changes from lowland to highland sites in the correlation between the trait value and genomic composition (designated by the proportion of marker alleles with the same origin). Joint analysis of quantitative trait loci (QTLs) over sites detected 5–8 QTLs for each trait (except disease scores, with data only from one site). With the exception of one QTL for TBN, none of these accounted for more than 15% of the total phenotypic variation. In total, detected QTLs accounted for 24–61% of the variation at each site on average. For yield, yield components and disease scores, alleles generally favored the site of origin. Highland-derived alleles had little effect at lowland sites, while lowland-derived alleles showed relatively broader adaptation. Gradual changes in the estimated QTL effects with increasing mean site temperature were observed, and paralleled the observed patterns of adaptation in highland and lowland germplasm. Several clusters of QTLs for different traits reflected the relative importance in the adaptation differences between the two germplasm types, and pleiotropy is suggested as the main cause for the clustering. Breeding for broad thermal adaptation should be possible by pooling genes showing adaptation to specific thermal regimes, though perhaps at the expense of reduced progress for adaptation to a specific site. Molecular marker-assisted selection would be an ideal tool for this task, since it could greatly reduce the linkage drag caused by the unintentional transfer of undesirable traits.
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    Genotype X environment interaction for bunch yield and its components in the oil palm (Elaeis guineensis, Jacq.) (1983)
    Springer
    Theoretical and applied genetics 64 (1983), S. 133-136 
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    ISSN: 1432-2242
    Keywords: Stability ; Adaptation ; Fitness trait ; Bunch yield ; Oil palm ; Elaeis guineensis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary There were significant differences between hybrids for number of bunches (NB), mean bunch weight (MBW) and fresh fruit bunch yield (FFB). For the hybrid population as a whole, significant hybrid X year (environment) effects were also observed for the two yield components and for yield per se. The linear component of the hybrid X year effect was also significant. There were highly significant and positive correlations between FFB, NB and MBW hybrid means and the regression co-efficients of the hybrid means on the environmental index. There were no significant associations between these means and mean square deviations from regression (s2d) for these traits.
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    URL: http://dx.doi.org/10.1007/BF00272720
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    Genotype x environment interaction in dairy cattle and its role in breeding programmes (1983)
    Springer
    Theoretical and applied genetics 66 (1983), S. 93-99 
    Details
    ISSN: 1432-2242
    Keywords: Lactation ; Milk yield ; Herd production ; Adaptation ; Dairy cattle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eighty thousand, one hundred and eleven records of the Israeli dairy herdbook for the period of 1973–1977 were studied and examined to determine the existence of Genotype x Environment Interaction (GxE) as affecting milk yield in kg per day between calvings. Various quantitative measures of environment were used while the genotypes were evaluated as the average performance of each sire's daughters in a whole range of environments. When the environment was evaluated as level of production, the relative importance of the interaction was found to be very low. Furthermore, the linear dependence on the interaction of the individual sires with the environments was found to be inconsistent with time, meaning that no justification was found for using specific adaptation patterns of genotypes to these environments. When lactation number and given time periods were used as environments, significant interactions were found between genotypes and environments. Results of the analyses of Genotype x Lactation interaction imply that the interaction values, to a certain degree, confused the differences between the sires when based on first lactation records. We therefore conclude that the need exists to expand the basis of sire evaluation, including the addition of data on successive lactation periods beyond the first one. We maintain that the genetic characteristic for this phenomenon is the “lactations development” of a sire, i.e., the performance of its daughters during the different lactations. The “maturing rhythm” of a sire may be regarded as a dynamic expression of the genetic makeup controlling lactation development. Furthermore, the prospect of selecting sires of bulls for early or late maturing could provide a new tool for the dairy cattle breeder.
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    URL: http://dx.doi.org/10.1007/BF00265180
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    Regression analysis of yield stability is strongly affected by companion test varieties and locations — examples from a study of Nordic barley lines (1996)
    Springer
    Theoretical and applied genetics 93 (1996), S. 468-476 
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    ISSN: 1432-2242
    Keywords: Adaptation ; Barley ; Genotype x environment interaction ; Regression analysis ; Repeatability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The suitability of regression analysis for studying the phenotypic stability of grain yield was investigated using a collection of 220 Nordic barley lines. Linear regression explained 26–52% of the genotype x environment (GE) interactions in different groupings of the material. The regression coefficient, b i , measures the yield response of the i-th genotype to improved environmental conditions. Deviations from regression, S di 2 , have been used to estimate Tai's stability parameter, λ i , which is a measure of the phenotypic yield stability in the agronomic sense. Repeatability of b i , λ i , and grain yield was studied by means of correlations between estimates obtained in each experimental year. Yield had the highest repeatability, with correlations between years ranging from 0.57 to 0.85. In this study, regression coefficients and λ i -values were not repeatable, i.e. genotypes reacted differentially to the yearly climatic variations. Six-rowed (6r) barleys had higher responsiveness, but lower mean yields, than two-rowed (2r) barleys. This is partly due to the history of selection of 6r-barleys, which mainly originate from regions with low potential yield levels, i.e. Finland and Norway. In general, responsiveness and stability were not correlated with yield. The highest-yielding lines had b i ≈1. The response pattern of the different types of barleys used in this study show that responsiveness can be changed by recombination.
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    URL: http://dx.doi.org/10.1007/BF00223192
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    Geographical variation in heading traits in wild emmer wheat, Triticum dicoccoides. I. Variation in vernalization response and ecological differentiation (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 546-552 
    Details
    ISSN: 1432-2242
    Keywords: Key words Vernalization ; Narrow-sense earliness ; Adaptation ; Ecological differentiation ; T. dicoccoides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Geographical variation in vernalization response and narrow-sense earliness was investigated for accessions of wild emmer wheat, Triticum dicoccoides, collected in Israel. Wide variation between and within populations was observed in both characters. The analysis of vernalization response showed that 2 accessions from Tabigha were of a strong spring growth habit, and thus wild emmer wheat was classified into four types, i.e., strongly spring type, moderately spring type, moderately winter type, and strongly winter type, according to their vernalization response. Whereas winter types were frequently found in most populations except that of Tabigha, the distribution of spring types was sporadic and restricted to warmer areas. It was thus suggested that spring type in T. dicoccoides might have evolved from a winter prototype as an adaptation to warmer conditions. Within moderately winter and moderately spring types, quantitative differences in vernalization response, measured as Dof70/Dof20 and Dof20/Dof0, were observed between populations. Inter- and intra-population variation in vernalization response could be explained to some extent by the difference in growing conditions at each habitat. It was clearly indicated that environmental heterogeneity caused ecogenetic differentiation in wild emmer wheat in Israel. Wild emmer wheat also varied considerably for narrow-sense earliness, ranging from 32.9 days to 69.5 days among accessions. However, it was difficult to explain its geographical variation simply by a linear relationship with environmental factors, and a nonlinear relationship and/or unknown microgeographic heterogeneity may be responsible.
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    Genetic basis of adaptation: flowering time in Arabidopsis thaliana (1997)
    Springer
    Theoretical and applied genetics 95 (1997), S. 573-583 
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    ISSN: 1432-2242
    Keywords: Key words QTL-mapping ; Adaptation ; Flowering time ; Arabidopsis thaliana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have mapped QTLs (quantitative trait loci) for an adaptive trait, flowering time, in a selfing annual, Arabidopsis thaliana. To obtain a mapping population we made a cross between an early-summer, annual strain, Li-5, and an individual from a late over-wintering natural population, Naantali. From the backcross to Li-5 298 progeny were grown, of which 93 of the most extreme individuals were genotyped. The data were analysed with both interval mapping and composite interval mapping methods to reveal one major and six minor QTLs, with at least one QTL on each of the five chromosomes. The QTL on chromosome 4 was a major one with an effect of 17.3 days on flowering time and explaining 53.4% of the total variance. The others had effects of at most 6.5 days, and they accounted for only small portions of the variance. Epistasis was indicated between one pair of the QTLs. The result of finding one major QTL and little epistasis agrees with previous studies on flowering time in Arabidopsis thaliana and other species. That several QTLs were found was expected considering the large number of possible candidate loci. In the light of the suggested genetic models of gene action at the candidate loci, epistasis was to be expected. The data showed that major QTLs for adaptive traits can be detected in non-domesticated species.
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    URL: http://dx.doi.org/10.1007/s001220050598
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    Analysis of the rye chromosome constitution and the amount of telomeric heterochromatin in the widely and narrowly adapted hexaploid triticales (1981)
    Springer
    Theoretical and applied genetics 60 (1981), S. 145-149 
    Details
    ISSN: 1432-2242
    Keywords: Triticale ; Rye ; Hexaploids ; Adaptation ; Chromosomal substitutions ; Modified chromosomes ; Telomeric heterochromatin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Investigations were made on the rye chromosome constitution and on the presence of telomeric heterochromatin in rye chromosomes of the 26 most widely and 24 most narrowly adapted triticale strains. Among widely adapted lines, 22 (85%) had a complete rye genome and four triticales only had chromosomal R-D genome substitutions. Twenty-three (96%) of the 24 most narrowly adapted triticales had substitutions between the chromosomes of the R and D genomes. The most widely adapted triticales accumulated fewer modified rye chromosomes in comparison to narrowly adapted lines. They had from one to three rye chromosomes with heterochromatic deletions: 46% of widely adapted lines had two modified rye chromosomes; 34% had three modified rye chromosomes, and 19% had a single modified rye chromosome. In widely adapted strains, the 1R, 4R, 5R and 6R modified chromosomes were observed; they were present in 80%, 73%, 50% and 11% of the cases, respectively. The most narrowly adapted triticales had from two to four modified rye chromosomes: 58% of the strains had three modified rye chromosomes; 29% had four modified rye chromosomes and 12% had two modified rye chromosomes. The modified 4R and 5R chromosomes were present in all of these lines. The 1R (modified), 6R (modified) and 7R (modified) were found in 83%, 25% and 16%, respectively, of the narrowly adapted strains. Results support the previous observations (Pilch 1980b) that a wide adaptation of hexaploid triticales is associated with the presence of the full potential of rye genome, and that it is independent of the amount of telomeric heterochromatin possessed by rye chromosomes.
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    Offspring sex ratio response to host size in the parasitoid wasp Spalangia endius (1999)
    Springer
    Behavioral ecology and sociobiology 46 (1999), S. 325-332 
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    ISSN: 1432-0762
    Keywords: Key words Sex ratio ; Host size ; Parasitoid wasp ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The host size model, an adaptive model for maternal manipulation of offspring sex ratio, was examined for the parasitoid wasp Spalangia endius. In a Florida strain, as the model predicts, daughters emerged from larger hosts than sons, but only when mothers received both small and large hosts simultaneously. The pattern appeared to result from the mother's ovipositional choice and not from differential mortality of the sexes during development. If sex ratio manipulation is adaptive in the Florida strain, it appears to be through a benefit to daughters of developing on large hosts rather than through a benefit to sons of developing on small hosts. Both female and male parasitoids were larger when they developed on larger hosts. For females, developing on a larger host (1) increased offspring production, except for the largest hosts, (2) increased longevity, (3) lengthened development, and (4) had no effect on wing loading. For males, development on a larger host had no effect on any measure of male fitness – mating success, longevity, development duration, or wing loading. In contrast, a strain from India showed no difference in the size of hosts from which daughters versus sons emerged, although both female and male parasitoids were larger when they developed on larger hosts. These results together with previous studies of Spalangia reveal no consistent connection between host-size-dependent sex ratio and host-size-dependent parasitoid size among strains of S. endius or among species of Spalangia.
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    Silvering and gill ”mitochondria-rich” cells in the eel, Anguilla anguilla (1995)
    Springer
    Cell & tissue research 281 (1995), S. 465-471 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Gills ; Epithelium ; Chloride cells ; Accessory cells ; Adaptation ; Anguilla anguilla (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Gills of typical yellow and silver eels, Anguilla anguilla L., were examined by light and electron microscopy. In both eel types, ”mitochondria-rich” cells were located in the epithelium covering the primary lamellae and consisted of ”chloride cells” and ”accessory cells”. As compared to yellow eels, the primary gill epithelium of silver eels was thicker and contained larger and more numerous chloride cells with enlarged mitochondria. The accessory cells also increased in number but did not show significant modifications in their size or ultrastructural features. These observations indicate that, as far as mitochondria-rich cells are concerned, the silvering process in eels would be equivalent to smoltification in salmonids. It corresponds to a preparation for seawater life and is probably controlled by hormonal factors.
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    Adaptation-dependent plasticity of rod bipolar cell axon terminal morphology in the rat retina (1998)
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    Cell & tissue research 294 (1998), S. 243-251 
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    ISSN: 1432-0878
    Keywords: Key words Retina ; Synaptic plasticity ; Rod bipolar cells ; Adaptation ; Reconstruction ; 3D ; Protein kinase C ; Rat (Norwegian)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  We chose synaptic terminals of rat rod bipolar cells as a model system to study activity-related changes in the overall morphology and the fine structure of synaptic sites. Using confocal laser scanning microscopy in conjunction with three-dimensional reconstruction and electron microscopy, we examined the effect of light and dark adaptation on axon terminals identified by protein kinase C (PKC) immunoreactivity. Rod bipolar cell axon terminals consisted of 2–3 polymorphic boutons situated close to the ganglion cell layer and a single ovoid swelling located more distally. Both components of the terminal complex showed adaptation-dependent differences in the distribution of PKC immunoreactivity and in their morphology. In light-adapted rod bipolar cell axon terminals, PKC immunoreactivity was homogeneously distributed throughout the cytoplasm, whereas terminals from dark-adapted animals showed PKC immunoreactivity preferentially localised in the submembrane compartment and a reduced staining of the more central cytoplasm. In three-dimensional reconstructions of optical sections and at the ultrastructural level, the shape of light-adapted axon terminals was round and smooth and exhibited more convexly curved synaptic membranes. In contrast, dark-adapted terminals had irregular contours, numerous dimples and a concave synaptic curvature. No spinules of bipolar cell terminals were observed in dark-adapted material. These observations are discussed in the context of activity-related morphological plasticity of central nervous system synapses and of the functions of PKC in the cycle of vesicle fusion and retrieval at the tonically active ribbon synapses of the rod bipolar axon terminal.
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    Silvering and gill “mitochondria-rich” cells in the eel, Anguilla anguilla (1995)
    Springer
    Cell & tissue research 281 (1995), S. 465-471 
    Details
    ISSN: 1432-0878
    Keywords: Gills ; Epithelium ; Chloride cells ; Accessory cells ; Adaptation ; Anguilla anguilla (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Gills of typical yellow and silver ells, Anguilla anguilla L., were examined by light and electron microscopy. In both eel types, “mitochondria-rich” cells were located in the epithelium covering the primary lamellae and consisted of“chloride cells” and “accessory cells”. As compared to yellow eels, the primary gill epithelium of silver eels was thicker and contained larger and more numerous chloride cells with enlarged mitochondria. The accessory cells also increased in number but did not show significant modifications in their size or ultrastructural features. These observations indicate that, as far as mitochondria-rich cells are concerned, the silvering process in eels would be equivalent to smoltification in salmonids. It corresponds to a preparation for seawater life and is probably controlled by hormonal factors.
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    Phosphorylation of the pheromone-responsive Gβ protein of Saccharomyces cerevisiae does not affect its mating-specific signaling function (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 608-618 
    Details
    ISSN: 1617-4623
    Keywords: Key wordsSaccharomyces cerevisiae ; Mating response ; Signal transduction ; Gβ phosphorylation ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The pheromone-responsive Gβ subunit of Saccharomyces cerevisiae (encoded by STE4) is rapidly phosphorylated at multiple sites when yeast cells are exposed to mating pheromone. It has been shown that a mutant form of Ste4 lacking residues 310–346, ste4Δ310–346, cannot be phosphorylated, and that its expression leads to defects in recovery from pheromone stimulation. Based on these observations, it was proposed that phosphorylation of Ste4 is associated with an adaptive response to mating pheromone. In this study we used site-directed mutagenesis to create two phosphorylation null (Pho−) alleles of STE4: ste4-T320 A/S335A and ste4-T322 A/S335A and ste4-T322A/S335A. When expressed in yeast, these mutant forms of Ste4 remained unphosphorylated upon pheromone stimulation. The elimination of Ste4 phosphorylation has no discernible effect on either signaling or adaptation. In addition, disruption of the FUS3 gene, which encodes a pheromone-specific MAP kinase, leads to partial loss of pheromone-induced Ste4 phosphorylation. Two-hybrid analysis suggests that the ste4Δ310–346 deletion mutant is impaired in its interaction with Gpa1, the pheromone-responsive Gα of yeast, whereas the Ste4-T320A/S335A mutant has normal affinity for Gpa1. Taken together, these results indicate that pheromone-induced phosphorylation of Ste4 is not an adaptive mechanism, and that the adaptive defect exhibited by the 310–346 deletion mutant is likely to be due to disruption of the interaction between Ste4 and Gpa1.
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    Adaptive locomotion to periodic perturbation. Adaptation mechanism with coupling of oscillator and link dynamics (1999)
    Springer
    Artificial life and robotics 3 (1999), S. 97-101 
    Details
    ISSN: 1614-7456
    Keywords: Quadrupedal locomotion ; Gait pattern ; Adaptation ; Periodic perturbation ; Coupled oscillators ; Limb dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Quadrupeds can acquire new gait patterns with respect to environmental changes. Yanagihara et al. have demonstrated this adaptability by experiments on a decerebrate cat. These experiments indicate that quadrupeds gradually adapt to their environment by repeating locomotion in a steady environment, and that the acquired gait pattern is persistently memorized after the locomotion. Our research aims at formulating a mathematical model of these cats' behavior and constructing a quadrupedal walking robot to realize such adaptive behavior. To date, we have proposed a mathematical description of adaptation at the level of gait pattern generation using neural oscillators. In this paper, we extend it to take into account limb dynamics. We study how to design the interaction of the oscillator and limb dynamics.
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    Effects of nickel on the rates of endocytosis, motility, and proliferation inTetrahymena and determinations on the cell content of the metal (1983)
    Springer
    Protoplasma 118 (1983), S. 140-147 
    Details
    ISSN: 1615-6102
    Keywords: Nickel ; Endocytosis ; Motility ; Proliferation ; Cellular nickel content ; Adaptation ; Tetrahymena pyriformis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary At concentrations above 1 mM, nickel has a dose-dependent effect on the rate of food vacuole formation in cells in the growth medium, proteose peptone (PP); total inhibition of endocytosis occurs within 10 minutes in 6mM nickel. However, only a 10 times lower concentration of nickel is tolerated by starved cells in an inorganic salt medium, a difference which may be ascribed to the high binding property of nickel to organic material. In the PP medium, nickel affects cell motility by increasing the rate of movement at a concentration of 1 mM, and by causing immobilization after 30 minutes in 6mM nickel; a spontaneous, partial recovery of cell motility is seen after 3 hours in 6 mM nickel. The effects of nickel on endocytosis and cell motility are reversible after removal of nickel. Cell proliferation continues at a reduced rate in 1 mM nickel, while only 1 1/2 cell doublings are achieved in 3 mM nickel during a 72-hour exposure, and no proliferation occurs in 6mM nickel, where an increasing cell mortality is observed after 12 hours. The cell content of nickel relates initially to the external concentration of the metal; however, cells in 1 mM nickel are capable of maintaining a constant content of the metal, whereas in 3 mM, the rate of accumulation is reduced after 3 hours, and cells in 6mM nickel accumulate the metal at a constant rate. All nickel-treated cells contain small refractive granules, previously proposed as representing an ion-regulating system, and the apparent adaption ofTetrahymena to the effects of nickel may be ascribed to such a regulation of the intracellular concentration of the metal.
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    Vision chip architecture with light adaptation mechanism (1998)
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    Artificial life and robotics 2 (1998), S. 12-18 
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    ISSN: 1614-7456
    Keywords: Regularization ; Vision chip ; Adaptation ; Retina ; Analog CMOS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Light adaptive algorithms/architectures are proposed for regularization vision chips. The adaptation mechanisms allow the regularization parameters to change in an adaptive manner in accordance with the light intensity of given images. This is achieved by adaptively changing the conductance values associated with massively parallel resistive networks. The algorithms/architectures are inspired by the adaptation mechanisms of the retinal horizonal cells of the lower vertebrates.
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    Adaptational changes of plastids in the leaves ofLigustrum ovalifolium Hassk. var.aureum at different light intensities (1984)
    Springer
    Protoplasma 122 (1984), S. 132-137 
    Details
    ISSN: 1615-6102
    Keywords: Adaptation ; Light intensity ; Ligustrum ; Plastids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The capacity of adaptation and the range of adjustment to different light conditions in fully expanded mutant leaves were studied on an aurea variety of privet (Ligustrum ovalifolium Hassk. var.aureum). Whenever the light conditions are altered leaves respond immediately. Although adaptational changes in leaf thickness are not possible, the change in colour, as well as changes in pigment concentrations take place within several days. With increasing light intensity there is a marked decline in chlorophyll concentration and the carotenoid yield becomes much higher. Under low light conditions the chlorophyll content is high, while the carotenoid concentration drops significantly. The mutant chloroplasts from green leaves always have a well developed thylakoid system. The only difference between young green leaves (DG1) and older regreened ones (DG2) is in the number of thylakoids per granum (grana in older leaves consist of more thylakoids), while the stacking degree of thylakoids remains about the same (74 and 77% respectively). Depending on the previous light conditions fine structure of plastids in yellow leaves differs considerably. Young yellow leaves (Y0) contain plastids with longitudinal arrays of dilated thylakoids and prothylakoid bodies occasionally. Plastids from primarily green leaves which turned yellow afterwards in strong sunlight (Y1) are characterized by thylakoids densely packed into cup-shaped stacks, or large vesicles originating from dilated thylakoids. The stacking degree of thylakoids in sun exposed yellow leaves (determined only in Y0 leaves) is extremely low and reaches only 29%.
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    Heavy metal tolerance and accumulation in metallicolous and non-metallicolous populations of Thlaspi caerulescens from continental Europe (1997)
    Springer
    Plant ecology 133 (1997), S. 221-231 
    Details
    ISSN: 1573-5052
    Keywords: Adaptation ; Genetic variation ; Lead ; Mineral nutrients ; Population differentiation ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In continental Europe, the heavy metal hyperaccumulator Thlaspi caerulescens occurs both on heavy-metal polluted soils (subsp. calaminare) and on soils with normal heavy metal content (subsp. caerulescens). In order to assess the extent and partitioning of variation in heavy metal tolerance and foliar mineral composition, twelve families from two populations of each subspecies were grown in pots in four soil treatments differing in heavy metal (Zn, Pb) and macronutrient concentrations. The two subspecies differed systematically in many respects. Subsp. calaminare had a higher survival at high levels of heavy metals and a higher tolerance index in all treatments. It also had three times lower foliar zinc and lead concentrations when grown at moderate levels of heavy metals. This, together with a negative correlation of foliar Pb concentration with growth in subsp. caerulescens, suggests that heavy metal accumulation per se is not a mechanism of tolerance in this species. Variation among families within populations accounted for a larger proportion of total variance in growth and mineral composition than variation between populations. Additionally, within population variation in heavy metal tolerance and accumulation was significantly lower in subsp. calaminare. This suggests that, adding to a background constitutive tolerance at the species level, natural selection has increased heavy metal tolerance in metallicolous populations of Thlaspi caerulescens.
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    Phenological spread in plants: A result of adaptations to environmental stochasticity? (1980)
    Springer
    Plant ecology 43 (1980), S. 83-86 
    Details
    ISSN: 1573-5052
    Keywords: Adaptation ; Colonization ; Environmental stochasticity ; Phenology ; Weather variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Plant species co-inhabiting a given geographical region often have distinetly different times of flowering. It is shown that such phenological spread, duc to short-term stochastic variation in weather variables, relaxes competition for empty sites to be colonized by diaspores. For sufficiently large spreads stable coexistence becomes possible. The applicability of the proposed hypothesis to the observed instances of phenological spread is discussed and shown to extend beyond that of other current theories.
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    Patterns of trait variation in the diploid wheats (Triticum, Aegilops) and the tetraploid speciesTriticum diccocoides (1983)
    Springer
    Plant systematics and evolution 143 (1983), S. 257-275 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Aegilops ; Triticum ; T. diccocoides ; wheat ; Adaptation ; trait variation ; factor analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eighteen earliness and morphological traits were examined in from 2 to 14 lines each of 10 diploid members of the wheat complex,Triticum-Aegilops, and 15 lines of the tetraploid speciesTriticum diccocoides. In general, earliness traits have the greatest relative between line vs. within line variation of all the traits examined. Within species, earliness traits are the principle set of characters around which evolve between line trait differences, one of the most important oich is leaf dimensions. At the genus level, earliness traits are independent of leaf dimensions and plant height characters. Thus, the pattern of evolution at the genus level is different from that exhibited in each of the species. Biological and evolutionary implications of these findings are discussed.
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    Nitrate production in the rhizosphere of Plantago species (1981)
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    Plant and soil 61 (1981), S. 43-52 
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    ISSN: 1573-5036
    Keywords: Adaptation ; Allelopathy ; Ecophysiology ; Grassland ; Plantago ; Nitrate production ; Nitrate reductase ; Nitrate uptake ; Nitrification ; Nitrifying bacteria ; Rhizosphere ; Root environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The production of nitrate in an old established dune grassland soil and its uptake by plants was studied by comparing amounts of mineral nitrogen and numbers of nitrifying bacteria in the rhizosphere on the one hand, and on the other accumulated nitrate and levels of nitrate reductase (NaR) of individual plants of three Plantago species,i. e., P. major, P. lanceolata andP. coronopus. For these three Plantago species andP. media basal levels of NaR in the absence of nitrate were determined in plants grown in culture solutions. The basal NaR levels ofP. major andP. media (species occurring on nutrient-rich soils) were significantly higher than those ofP. lanceolata andP. coronopus (species found on nutrient-poor soils). NaR activity increased in the presence of nitrate and was suppressed by ammonium. From the numbers of nitrifying bacteria in the rhizosphere and NaR activity in the leaves it was concluded that nitrate was produced in the root environments of the three Plantago species and that the compound was taken up by the plants. NaR activities and numbers of nitrifying bacteria were higher for individuals ofP. major than for those ofP. lanceolata andP. coronopus. No correlation was found between the ammonium levels and the numbers of nitrifying bacteria in the soil, and no indications of inhibition of nitrifying bacteria in the rhizosphere were obtained. For individuals ofP. lanceolata a correlation was found between the numbers of nitrifying bacteria in the soil and NaR activity in the leaves. The results are discussed in relation to the ecological habitats of the three species.
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    URL: http://dx.doi.org/10.1007/BF02277361
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    Obtention d'un mutant deRhizobium meliloti adapté aux cultures de luzerne en terres acides (1981)
    Springer
    Plant and soil 60 (1981), S. 99-110 
    Details
    ISSN: 1573-5036
    Keywords: Adaptation ; Luzerne ; Mutant ; Rhizobium meliloti ; Terres acides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Resume Un mutant acido-tolérant deR. meliloti a été isolé. Le caractère de résistance en milieu acide n'a pas été obtenu par adaptation sur des milieux de plus en plus acides mais par mutagenèses successives provoquées par la N-méthyl-N'nitroso-N-nitrosoguanidine (NTG) et sélection sur milieu acide de façon à rendre stable le caractère acido-tolérant. Ce mutant acide présente la propriété de se développer plus lentement que la souche sauvage sur milieu pauvre. Ceci ne l'empêche pas de présenter sensiblement la même efficience que cette dernière à pH voisin de la neutralité en milieu synthétique. L'étude comparative de l'efficience de la souche parentale et de la souche mutée sur la luzerne cultivée en terre acide est rendue difficile du fait de la présence de nitrates qui réduit la nodulation et inhibe l'action de la nitrogénase: par épuisement, en effectuant une culture dense de luzerne sur cette terre, il est possible de mettre en évidence ensuite l'activité symbiotique importante à pH 5,9 du mutant par rapport à la souche sauvage.
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    Water relations, ethylene production, and morphological adaptation ofFraxinus pennsylvanica seedlings to flooding (1984)
    Springer
    Plant and soil 77 (1984), S. 183-192 
    Details
    ISSN: 1573-5036
    Keywords: Adaptation ; Adventitious roots ; Ethylene ; Flooding ; Fraxinus pennsylvanica ; Lenticels ; Turgidity ; Water potential ; Water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fraxinus pennsylvanica Marsh. seedlings that were 150 days old adapted well to flooding of soil with stagnant water for 28 days. Early stomatal closure, followed by reopening as well as hypertrophy of lenticels and formation of adventitious roots on submerged portions of stems appeared to be important adaptations for flood tolerance. Leaf water potential (ψ1) was consistently higher in flooded than in unflooded seedlings, indicating higher leaf turgidity in the former. This was the result of (1) early reduction in transpiration associated with stomatal closure, and (2) subsequently increased absorption of water by the newly-formed adventitious roots as stomata reopened and transpiration increased. Waterlogging of soil was followed by large increases in ethylene content of stems, both below and above the level of submersion. Formation of hypertrophied lenticels and adventitious roots on flooded plants was correlated with increased ethylene production. However, the involvement of various compounds other than ethylene in inducing morphological changes in flooded plants is also emphasized.
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    URL: http://dx.doi.org/10.1007/BF02182922
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    Physiological, morphological, and growth responses ofPlatanus occidentalis seedlings to flooding (1982)
    Springer
    Plant and soil 66 (1982), S. 243-255 
    Details
    ISSN: 1573-5036
    Keywords: Adaptation ; Adventitious roots ; Ethylene ; Flooding ; Growth of seedlings ; Lenticels ; Platanus occidentalis ; Stomatal aperture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Flooding ofPlatanus occidentalis L. seedlings for up to 40 days induced several changes including early stomatal closure, greatly accelerated ethylene production by stems, formation of hypertrophied lenticels and adventitious roots on submerged portions of stems, and marked growth inhibition. Poor adaptation ofPlatanus occidentalis seedlings to soil inundation was shown in stomatal closure during the entire flooding period, inhibition of root elongation and branching, and death of roots. Some adaptation to flooding was indicated by (1) production of hypertrophied lenticels which may assist in exchange of dissolved gases in flood water and in release of toxic compounds, and (2) production of adventitious roots on stems which may increase absorption of water. These adaptations appeared to be associated with greatly stimulated ethylene production in stems of flooded plants. The greater reduction of root growth over shoot growth in flooded seedlings will result in decreased drought tolerance after the flood waters recede. The generally low tolerance to flooding of seedlings of species that are widely rated as highly flood tolerant is emphasized.
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    URL: http://dx.doi.org/10.1007/BF02183983
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    Local variability in population structure and density of the protogynous reef herbivoreSparisoma viride (1996)
    Springer
    Environmental biology of fishes 47 (1996), S. 65-80 
    Details
    ISSN: 1573-5133
    Keywords: Adaptation ; Territoriality ; Life history ; Mating ; Grazing pressure ; Coral reef ; Reproduction ; Scaridae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis We compare the (relative) abundance of life phases [juveniles (JU), initial phase (IP) and terminal phase (TP) fish], social categories (territorial and group adults), and fish following alternative mating styles, in three local populations of the protogynous reef herbivore,Sparisoma viride, on the fringing reef of Bonaire (Netherlands Antilles). In order to determine the adaptive significance of variations in social organization, they are related to the density of conspecifics and other herbivores and to the availability of food, shelter and mating sites. The most striking difference is the high abundance of JU and group fish at one location (Playa Frans) and the total absence of group fish at another (Red Slave). These differences are coherent with a gradient in population density, total herbivore density, scarid grazing pressure, and reproductive output, all of which are highest at Playa Frans and lowest at Red Slave. Exposure to waves and currents shows an inverse trend. The differences in the relative abundance of territorial fish can be explained by the concept of economic defendability, which is reduced at higher population density. In a life history context, small TP group males represent ‘bachelors’ that sacrifice current reproduction for better future prospects. As predicted by life history theory, early sex change is promoted at sites where the future rewards are higher (higher spawning rates of large TP males) and where the costs incurred during the bachelor phase are reduced (more spawning opportunities for group TP males). At Red Slave an alternative male mating style (‘streaking’) appears to be promoted by the lack of a refuge for group TP males and by a dense gorgonian canopy, allowing IP males to reside inside territories. We conclude that most observed differences in population structure can be considered adaptive in an ecological and in a life history context. Population density is a major factor in both contexts. Analysis of the variability in adult density in relation to JU density and the availability of food and shelter indicates that theS. viride populations at Bonaire are not totally controlled by stochastic processes. Considering the small spatial scale and the high dispersal of the planktonic embryos and larvae, the observed variability in behavioural and life history traits ofS. viride points to a high degree of phenotypic plasticity.
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    An improvement in Pichia stipitis fermentation of acid-hydrolysed hemicellulose achieved by overliming (calcium hydroxide treatment) and strain adaptation (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 281-283 
    Details
    ISSN: 1573-0972
    Keywords: Adaptation ; fermentation ; hemicellulose ; hydrolysate ; overliming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The fermentability of a corn cob, acid-hydrolysed hemicellulose by Pichia stipitis was considerably improved by pre-treatment with Ca(OH)2. The total sugars utilized and ethanol yield for the untreated hydrolysate were 18% and 0.21 g/g, respectively, compared with 82% and 0.32 g/g respectively for the treated material. Adaptation of the yeast to the hydrolysate resulted in a significantly higher fermentation rate with over 90% of the initial total sugars being utilized and an ethanol yield and maximum ethanol concentration of 0.41 g/g and 13.3 g/l, respectively.
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    URL: http://dx.doi.org/10.1007/BF00360928
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    Continuous anaerobic phenol degradation using an adapted mixed culture (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 409-411 
    Details
    ISSN: 1573-0972
    Keywords: Adaptation ; anaerobic ; packed bed ; phenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A mixed culture derived from cow dung and sewage sludge and adapted to phenol was used for anaerobic phenol degradation. The phenol degradation rate depended on the period of adaptation of the mixed culture to phenol. In the continuous process, a higher degradation rate (2500 mg.1-1 d-1) and better reactor stability was achieved with a granular activated-carbon-packed bed reactor than with a stirred tank reactor.
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    Factor Biases and Promoting Sustainable Development: Adaptation to Drought in the Senegal River Basin (1996)
    Springer
    Mitigation and adaptation strategies for global change 1 (1996), S. 139-165 
    Details
    ISSN: 1573-1596
    Keywords: Adaptation ; agriculture ; agroforestry ; climate change ; drought ; ecological degradation ; factor bias ; Senegal ; sustainability ; social relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Abstract The ongoing drought in the Sahel region of West Africa highlights the vulnerability of food-producing systems to climate change and variability. Adaptation to climate should therefore increase the sustainability of agriculture under a long-term drought. Progress towards sustainability and adaptation in the the Senegal River Basin is hampered by an existing set of social and ecological relationships that define the control over the means of production and how people interact with their environment. These relationships are sensitive to the technological inputs and the administration of food production, or the factor bias in the different policy alternatives for rural development. One option is based on state-controlled, irrigated plantations to provide rice (Oryza) for the capital, Dakar. This policy emphasizes a top-down management approach, mechanized agriculture and a reliance on external inputs which strengthens the relationships introduced during the colonial period. A time series decomposition of the annual flow in the Senegal River at Bakel in Senegal suggests that water resources availability has been substantially curtailed since 1960, and a review of the water resources budget or availability in the basin suggests that this policy's food production system is not sustainable under the current climate of the basin. Under these conditions, this program is exacerbating existing problems of landscape degradation and desertification, which increases rural poverty. A natural resource management policy offers two adaptation strategies that favour decentralized management and a reduction of external inputs. The first alternative, “Les Perimetres Irrigués”, emphasizes village-scale irrigation, low water consumption cereal crops and traditional socio-political structures. The second alternative emphasizes farm-level irrigation and agro-forestry projects to redress the primary effects of desertification. The water requirements of both the rice import substitution program and the natural resource management program are calculated. A water resources simulation model/optimization analysis using dynamic programming is used to compare these two alternatives to the rice import substitution programs. Results indicate that the natural resource management policy could potentially bring a large area into production while using far less water than the rice import substitution program. The natural resource management policy, in particular the second alternative with its emphasis on individual ownership and ecological rehabiliation, defines a different set of social and ecological relationships that appear to enhance the sustainability of food production under a long-term drought.
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    URL: http://dx.doi.org/10.1023/B:MITI.0000027382.26287.8c
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    CADREM: A case-based system for conceptual structural design (1997)
    Springer
    Engineering with computers 13 (1997), S. 153-164 
    Details
    ISSN: 1435-5663
    Keywords: Artificial intelligence ; Case-based reasoning ; Design methods ; Representation ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper proposes an approach for reusing design methods from past designs for solving new problems. This is an application of case-based reasoning to design. The proposed approach is implemented as a prototype system called CADREM. CADREM has been tried in the domain of conceptual structural design of buildings. First, a description of case-based reasoning is given followed by its application in design. Then follows a description of the proposed approach and CADREM. Sample outputs from CADREM are also included.
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    URL: http://dx.doi.org/10.1007/BF01221212
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    Simulating convesations: The communion game (1995)
    Springer
    AI & society 9 (1995), S. 116-137 
    Details
    ISSN: 1435-5655
    Keywords: Adaptation ; AI ; Conversation ; Corrdination ; Imitation game ; Language ; Machine learning ; Turing test ; Simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract In their enthusiasm for programming, computational linguists have tended to lose sight of what humansdo. They have conceived of conversations as independent of sound and the bodies that produce it. Thus, implicit in their simulations is the assumption that the text is the essence of talk. In fact, unlike electronic mail, conversations are acoustic events. During everyday talk, human understanding depends both on the words spoken and on fine interpersonal vocal coordination. When utterances are analysed into sequences of word-based forms, however, these prosodic aspects of language disappear. Therefore, to investigate the possibility that machines might talk, we propose acommunion game that includes this interpersonal patterning. Humans and machines would talk together and, based on recordings of them, a panel would appraise the relevant merit of each machine's simulation by how true to life it sounded. Unlike Turing's imitation game, the communion game overtly focuses attention, not on intelligence, but on language. It is designed to facilitate the development of social groups of adaptive robots that exploit complex acoustic signals in real time. We consider how the development of such machines might be approached.
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    URL: http://dx.doi.org/10.1007/BF01210600
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    Perspectives on the ecomorphology of bony fishes (1995)
    Springer
    Environmental biology of fishes 44 (1995), S. 11-20 
    Details
    ISSN: 1573-5133
    Keywords: Morphology ; Ecology ; Form ; Biological role ; Performance ; Ontogeny ; Optimization ; Phylogeny ; Constraints ; Adaptation ; Fundamental niche ; Realized niche
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The field of ecomorphology has a long history with early roots in Europe. In this half of the century the application of ecomorphology to the biology of fishes has developed in the former Soviet Union, Poland and Czechoslovakia, The Netherlands, and in North America. While the specific approaches vary among countries, many North American studies begin by comparing morphological variation with variation in ecological characteristics at the intra or interspecific levels. These initial correlative studies form the ground work for hypotheses that explore the mechanistic underpinnings of the observed ecomorphological associations. Supporting these mechanistic hypotheses are insights from functional studies which demonstrate the limits to potential resource use resulting from a particular morphology; however, the actual resource use is likely to be more limited due to additional constraints provided by internal (e.g., behavior, physiology) and external (e.g., resource abundance, predator distribution) factors. The results from performance studies in the laboratory or field can be used to test specific ecomorphological hypotheses developed from the initial correlational and functional studies. Such studies may, but rarely do, incorporate an ontogenetic analysis of the ecomorphological association to determine their effect on performance. Finally, input from phylogenetic analyses allow an investigator to examine the evolution of specific features and to assess the rates and directionality of character evolution. The structural and ecological diversity of fishes provides a fertile ground to investigate these interactions. The contributions in this volume highlight some of the specific directions for ecomorphological research covering a variety of biological processes in fishes. These include foraging, locomotion, reproduction, respiration, and sensory systems. Running through these papers are new insights into universal ecomorphological issues, i.e., the relationships between form and ecological role and the factors that modify these relationships.
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    Early ontogeny of white sucker,Catostomus commersoni, with steps of saltatory development (1980)
    Springer
    Environmental biology of fishes 5 (1980), S. 191-224 
    Details
    ISSN: 1573-5133
    Keywords: Adaptation ; Benzidine stain ; Catostomid ; Discontinuity theory ; Ecomorphology ; Embryology ; Fish ; Haemoglobin stain ; Hatching ; Peroxidase ; Thresholds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Frequent and detailed observations of arbitrary stages revealed a saltatory pattern of development in the early ontogeny of fluvial spawning white sucker. Considered as adaptations for respiration were: i) expansion of the surface area of the yolk through a change in yolk shape, ii) the presence of carotenoid pigment in the yolk, iii) a large caudal vein sinus, iv) coverage of the yolk surface with capillaries of bilaterally paired vitelline plexi, and v) a large pair of vitelline veins. The ability to swim developed slowly and well after hatching. Young suckers would therefore spend most of the eleutheroembryonic phase in the interstices of the rock substrate of the spawning ground. The change from a benthic to pelagic mode of existence occurred with swimbladder inflation and before the start of exogenous feeding.
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    Two Strategies of Adaptive Cluster Covering with Descent and Their Comparison to Other Algorithms (1999)
    Springer
    Journal of global optimization 14 (1999), S. 55-78 
    Details
    ISSN: 1573-2916
    Keywords: Adaptation ; Clustering ; Covering ; Descent ; Global optimization ; Parameter identification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Two strategies of randomized search, namely adaptive cluster covering (ACCO), and adaptive cluster covering with descent (ACD), are introduced and positioned in the group of the global optimization techniques. Several algorithms based on these new strategies are compared with other techniques of global randomized search in terms of effectiveness, efficiency and reliability. The other techniques include two versions of multistart, two versions of the controlled random search (CRS2 and CRS4) and the canonical genetic algorithm. Thirteen minimization problems including two parameter identification problems (for a flexible membrane mirror model and a hydrologic model) are solved. The algorithm ACCO, and a version of CRS4 algorithm (Ali and Storey 1994) show the highest efficiency, effectiveness and reliability. The second new algorithm, ACD, is in some runs very efficient and effective, but its reliability needs further improvement.
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    URL: http://dx.doi.org/10.1023/A:1008334632441
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    Kidney structure and function of obligate and facultative hibernators: the white-tailed prairie dog (Cynomys leucurus) and the black-tailed prairie dog (Cynomys ludovicianus) (1995)
    Springer
    Journal of comparative physiology 165 (1995), S. 320-328 
    Details
    ISSN: 1432-136X
    Keywords: Hibernation ; Adaptation ; Urine ; Kidney ; Prairie dog, Cynomys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The white-tailed prairie dog is an obligate hibernator that enters a heterothermic phase when maintained in the cold with low intensity light and ad libitum food and water. The black-tailed prairie dog (a facultative hibernator) will not hibernate under similar conditions. It has been suggested that the black tailed prairie dog remains active during the winter because it can conserve water more effectively due to a more efficient kidney. The present study revealed no significant differences between the species in renal morphology: relative medullary thickness, nephron heterogeneity, renal vasculature, or fornix dimensions, all of which are structures associated with the urinary concentrating mechanism. In addition, there was no difference in number of nephrons between the two species. The black-tailed prairie dog does produce a more concentrated urine when food and water deprived. However, this difference was not observed when the animals were salt loaded. The water-deprivation and salt-loading experiments suggest that the higher urine osmolality produced by the back-tailed prairie dog during fasting is a result of a higher urea load due to a greater protein catabolism and not because of a differential capacity to concentrate urine.
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    Quantitative topography of organelles in the liver (1981)
    Springer
    Cell & tissue research 221 (1981), S. 209-220 
    Details
    ISSN: 1432-0878
    Keywords: Liver (Rat) ; Organelle topography ; Adaptation ; Fructose ; Quantitation ; Histochemistry ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary After seven days of feeding fructose the liver of Wistar rats showed enormous accumulations of glycogen, which completely altered the original pattern of distribution of organelles. A quantitative morphological method was used to analyze these changes. The cytoplasm was mapped into arbitrary “distance classes” corresponding to concentric rings beginning at the outer nuclear membrane. This allowed the density of organelles in a given zone to be estimated. In cells filled with glycogen as a result of the fructose feeding, the following rearrangements were found: in the intermediate zone of both cellular poles (i.e., bile canalicular pole and sinusoidal pole) the mitochondria disappeared, being replaced by glycogen. The endoplasmic reticulum was accumulated in the perinuclear zone of both cellular poles, as in control animals, but was reduced throughout the rest of cytoplasm. It showed a peripheral density maximum at the biliary canalicular pole, in contrast to the cells of control animals. These changes in the distribution of the organelles and cellular “compartments” correspond to histochemical findings and demonstrate an adaptive reaction in the liver parenchyma to fructose ingestion, the organelles arranging themselves in cytoplasmic regions which still show a metabolic activity.
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    Curved-flow, rolling-flow, and oscillatory pure-yawing wind-tunnel test methods for determination of dynamic stability derivatives (1981)
    In:  CASI
    Details
    Publication Date: 2011-10-14
    Description: The test capabilities of the Stability Wind Tunnel of the Virginia Polytechnic Institute and State University are described, and calibrations for curved and rolling flow techniques are given. Oscillatory snaking tests to determine pure yawing derivatives are considered. Representative aerodynamic data obtained for a current fighter configuration using the curved and rolling flow techniques are presented. The application of dynamic derivatives obtained in such tests to the analysis of airplane motions in general, and to high angle of attack flight conditions in particular, is discussed.
    Keywords: AERODYNAMICS
    Type: AGARD Dyn. Stability Parameters; 13 p
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    Buffeting tests in a cryogenic windtunnel (1995)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Measurements of wing buffeting, using root strain gages, were made in the NASA Langley 0.3 m cryogenic wind tunnel to refine techniques which will be used in larger cryogenic facilities such as the United States National Transonic Facility (NTF) and the European Transonic Wind Tunnel (ETW). The questions addressed included the relative importance variations in frequency parameter and Reynolds number, the choice of model material (considering both stiffness and damping) and the effects of static aeroelastic distortion. The main series of tests was made on three half models of slender 65 deg delta wings with a sharp leading edge. The three delta wings had the same planform but widely differing bending stiffnesses and frequencies (obtained by varying both the material and the thickness of the wings). It was known that the steady flow on this configuration would be insensitive to variations in Reynolds number. On this wing at vortex breakdown the spectrum of the unsteady excitation is unusual, having a sharp peak at particular frequency parameter. Additional tests were made on one unswept half-wing of aspect ratio 1.5 with an NPL 9510 aerofoil section, known to be sensitive to variations in Reynolds number at transonic speeds. The test Mach numbers were M = 0.21 and 0.35 for the delta wings and to M = 0.30 for the unswept wing. On this wing the unsteady excitation spectrum is fairly flat (as on most wings). Hence correct representation of the frequency parameter is not particularly important.
    Keywords: AERODYNAMICS
    Type: Aeronautical Journal (ISSN 0001-9240); 99; 981; p. 1-14
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    In-flight lift and drag measurements on a first generation jet transport equipped with winglets (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A KC-135A aircraft equipped with wing tip winglets was flight tested to demonstrate and validate the potential performance gain of the winglet concept as predicted from analytical and wind tunnel data. Flight data were obtained at cruise conditions for Mach numbers of 0.70, 0.75, and 0.80 at a nominal altitude of 36,000 ft. and winglet configurations of 15 deg cant/-4 deg incidence, 0 deg cant/-4 deg incidence, and baseline. For the Mach numbers tested the data show that the addition of winglets did not affect the lifting characteristics of the wing. However, both winglet configurations showed a drag reduction over the baseline configuration, with the best winglet configuration being the 15 deg cant/-4 deg incidence configuration. This drag reduction due to winglets also increased with increasing lift coefficient. It was also shown that a small difference exists between the 15 deg cant/-4 deg incidence flight and wind tunnel predicted data. This difference was attributed to the pillowing of the winglet skins in flight which would decrease the winglet performance.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 103-116
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    KC-135 winglet program overview (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A joint NASA/USAF program was conducted to accomplish the following objectives: (1) evaluate the benefits that could be achieved from the application of winglets to KC-135 aircraft; and (2) determine the ability of wind tunnel tests and analytical analysis to predict winglet characteristics. The program included wind-tunnel development of a test winglet configuration; analytical predictions of the changes to the aircraft resulting from the application of the test winglet; and finally, flight tests of the developed configuration. Pressure distribution, loads, stability and control, buffet, fuel mileage, and flutter data were obtained to fulfill the objectives of the program.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 1-46
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    KC-135 wing and winglet flight pressure distributions, loads, and wing deflection results with some wind tunnel comparisons (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: A full-scale winglet flight test on a KC-135 airplane with an upper winglet was conducted. Data were taken at Mach numbers from 0.70 to 0.82 at altitudes from 34,000 feet to 39,000 feet at stabilized flight conditions for wing/winglet configurations of basic wing tip, 15/-4 deg, 15/-2 deg, and 0/-4 deg winglet cant/incidence. An analysis of selected pressure distribution and data showed that with the basic wing tip, the flight and wind tunnel wing pressure distribution data showed good agreement. With winglets installed, the effects on the wing pressure distribution were mainly near the tip. Also, the flight and wind tunnel winglet pressure distributions had some significant differences primarily due to the oilcanning in flight. However, in general, the agreement was good. For the winglet cant and incidence configuration presented, the incidence had the largest effect on the winglet pressure distributions. The incremental flight wing deflection data showed that the semispan wind tunnel model did a reasonable job of simulating the aeroelastic effects at the wing tip. The flight loads data showed good agreement with predictions at the design point and also substantiated the predicted structural penalty (load increase) of the 15 deg cant/-2 deg incidence winglet configuration.
    Keywords: AERODYNAMICS
    Type: KC-135 Winglet Program Rev.; p 47-102
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  • 73
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    Status of advanced airfoil tests in the Langley 0.3-meter transonic cryogenic tunnel (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A joint NASA/U.S. industry program to test advanced technology airfoils in the Langley 0.3-meter Transonic Tunnel (TCT) was formulated under the Langley ACEE Project Office. The objectives include providing U.S. industry an opportunity to compare their most advanced airfoils to the latest NASA designs by means of high Reynolds number tests in the same facility. At the same time, industry would again experience in the design and construction of cryogenic test techniques. The status and details of the test program are presented. Typical aerodynamic results obtained, to date, are presented at chord Reynolds number up to 45 x 10(6) and are compared to results from other facilities and theory. Details of a joint agreement between NASA and the Deutsche Forschungs- und Versuchsantalt fur Luft- and Raumfahrt e.V. (DFVLR) for tests of two airfoils are also included. Results of these tests will be made available as soon as practical.
    Keywords: AERODYNAMICS
    Type: Advan. Aerodyn.: Selected NASA Res.; p 37-53
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  • 74
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    Component testing for dynamic model verification (1984)
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    Publication Date: 2006-02-14
    Description: Dynamic model verification is the process whereby an analytical model of a dynamic system is compared with experimental data, adjusted if necessary to bring it into agreement with the data, and then qualified for future use in predicting system response in a different dynamic environment. These are various ways to conduct model verification. The approach taken here employs Bayesian statistical parameter estimation. Unlike curve fitting, whose objective is to minimize the difference between some analytical function and a given quantity of test data (or curve), Bayesian estimation attempts also to minimize the difference between the parameter values of that funciton (the model) and their initial estimates, in a least squares sense. The objectives of dynamic model verification, therefore, are to produce a model which: (1) is in agreement with test data; (2) will assist in the interpretation of test data; (3) can be used to help verify a design; (4) will reliably predict performance; and (5) in the case of space structures, will facilitate dynamic control.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 15 p
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  • 75
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    Post and a random-walk search mode (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Multidisciplinary analysis often requires optimization of nonlinear systems that are subject to constraints. Trajectory optimization is one example of this situation. The Program to Optimize Simulated Trajectories (POST) was used successfully for a number of problems. The purpose is to describe POST and a new optimization approach that has been incorporated into it. Typical uses of POST will also be illustrated. The projected-gradient approach to optimization is the preferred option in POST and is discussed. A new approach to optimization, the random-walk approach, is described, and results with the random-walk approach are presented.
    Keywords: AERODYNAMICS
    Type: Recent Experiences in Multidisciplinary Analysis and Optimization, Part 2; 23 p
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  • 76
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    Wall interference measurements for three-dimensional models in transonic wind tunnels: Experimental difficulties (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The purpose is not to provide a detailed discussion of several wall interference experiments, but rather to use these experiments (recently accomplished in the Boeing Transonic Wind Tunnel (BTWT) to illustrate the problems associated with many of the measurements required by current wall interference assessment/correction (WIAC) procedures. The wall correction to lift is emphasized. It is shown that, because conventional tunnels and relatively small models continue to be used, the flow field or flow boundary measurements to be made impose severe requirements on the experiment itself. In some cases, existing instrumentation and test techniques may not be adequate to obtain the data accuracies needed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 21-42
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  • 77
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    Adaptation of a four-wall interference assessment/correction procedure for airfoil tests in the 0.3-m TCT (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Based upon limited, initial observations of wall interference corrections obtained for one airfoil test, there is a need for assessing the upstream flow direction. If there is no direct measurement then a two-pass correction procedure similar to the one described here is required. Questions have arisen pertaining to the correct interpretation of the pressure coefficients measured on the slats of a slotted tunnel wall, the interpretation of just what the calculated equivalent body encompasses or should include, and what can or should be considered as quantitative criteria for data correctability. Further studies using this modified procedure will address these questions. Hopefully, a meaningful WIAC procedure can be validated for the airfoil tests in the 0.3-m TCT.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 393-414
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  • 78
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    Some experience with Barnwell-Sewall type correction to two-dimensional airfoil data (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A series of airfoils were tested in the Langley 0.3-Meter Transonic Cryogenic Tunnel (TCT) at Reynolds numbers from 2 to 50 million. The 0.3-m TCT is equipped with Barnwell slots designed to minimize blockage due to the tunnel flow and ceiling. This design suggests that sidewall corrections for blockage is needed, and that a lifting airfoil produces a change in angle of attack. Sidewall correction methods were developed for subsonic and subsonic-transonic flow. Comparisons of theory with experimental data obtained in the 0.3-m TCT for two airfoils, the British NPL 9510 and the German R-4 are presented. The NPL 9510 was tested as part of the NASA/United Kingdom Joint Aeronautical Program and R-4 was tested as part f the DFVLR/NASA Advanced Airfoil Research Program. For the NPL 9510 airfoil, only those test points that one would anticipate being difficult to predict theoretically are presented.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 375-392
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  • 79
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    Experiences with a high-blockage model tested in the NASA Ames 12-foot pressure wind tunnel (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Representation of the flow around full-scale ships was sought in the subsonic wind tunnels in order to a Hain Reynolds numbers as high as possible. As part of the quest to attain the largest possible Reynolds number, large models with high blockage are used which result in significant wall interference effects. Some experiences with such a high blockage model tested in the NASA Ames 12-foot pressure wind tunnel are summarized. The main results of the experiment relating to wind tunnel wall interference effects are also presented.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 345-360
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  • 80
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    An inerference assessment approach for a three-dimensional slotted tunnel with sparse wall pressure data (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The various procedures referred to as wall interference assessment and correction procedures presume the existence of a surface distribution of data (usually static pressure) measured over a surface on or near the tunnel walls for each test point to be assessed. An alternative approach in which a reasonably sophisticated computer model of the test section flow would be fitted parametrically to a sparse set of measured data is presented. The measurements provides line distributions of static pressure near the center lines of the top, side and bottom walls. The development of a test section model incorporating explicit recognition of discrete slots of finite length with controlled flow reentry into the solid wall downstream portion of the tunnel is shown.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 323-334
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  • 81
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    Interference from slotted walls (1984)
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    Publication Date: 2006-02-14
    Description: Wall interference is made predominant in tunnel models and by wall geometries to facilitate the study of slot flow. The viscous effects in slots are studied by two dimensional measurements of flow. Wall interference is assessed by measuring pressure distributions at two levels near the walls. Interference on lifting delta wings is calculated. Pressure distributions at inner boundaries show basis axisymetries between the pressure side and the suction side, pointing to the necessity of having wider slots on the pressure side.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 293-300
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  • 82
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    Development in UK of a method for calculating tunnel wall corrections from flow measurements (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Classical methods for calculation of wall corrections which are not satisfactory for a number of flows of interest are discussed. To meet these objections, a number of methods were developed which use measurements of the low at or close to the tunnel walls as an outer boundary condition to define wall interference. The development, assessment and application of one such method is summarized.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 259-271
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  • 83
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    NLR activities in the field of wind tunnel wall interference (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Measured field data as a boundary condition for calculating the interference flow field were applied. They are divided into two categories. In the first category, the field data must consist of distributions of a single velocity component, and an accurate estimate of the hypothetical free air contribution of the model to this component is required. The differences between measured values and estimated model contributions are attributed to wall interference and they establish the boundary condition. The associated field data measurements are simple, yet the necessary model representation generally is a serious drawback. The second category requires field data which consist of velocity vector distributions at the price of multicomponent measurements, but at the profit that no information at all is required about the model. In solid wall test sections, the price is reduced to virtually zero but the profit remains.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 221-229
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  • 84
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    Performance of two transonic airfoil wind tunnels utilizing limited ventilation (1984)
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    Publication Date: 2006-02-14
    Description: A limited-zone ventilated wall panel was developed for a closed-wall icing tunnel which permitted correct simulation of transonic flow over model rotor airfoil sections with and without ice accretions. Candidate porous panels were tested in the Ohio State University 6- x 12-inch transonic airfoil tunnel and result in essentially interference-free flow, as evidenced by pressure distributions over a NACA 0012 airfoil for Mach numbers up to 0.75. Application to the NRC 12- x 12-inch icing tunnel showed a similar result, which allowed proper transonic flow simulation in that tunnel over its full speed range.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 165-170
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  • 85
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    Investigations of flow field perturbations induced on slotted transonic-tunnel walls (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The free-stream interference caused by the flow through the slotted walls of the test sections of transonic wind tunnels has continuously a problem in transonic tunnel testing. The adaptive-wall transonic tunnel is designed to actively control the near-wall boundary conditions by sucking or blowing through the wall. In order to make the adaptive-wall concept work, parameters for computational boundary conditions must be known. These parameters must be measured with sufficient accuracy to allow numerical convergence of the flow field computations and must be measured in an inviscid region away from the model that is placed inside the wind tunnel. The near-wall flow field was mapped in detail using a five-port cone probe that was traversed in a plane transverse to the free-stream flow. The initial experiments were made using a single slot and recent measurements used multiple slots, all with the tunnel empty. The projection of the flow field velocity vectors on the transverse plane revealed the presence of a vortex-like flow with vorticity in the free stream. The current research involves the measurement of the flow field above a multislotted system with segmented plenums behind it, in which the flow is controlled through several plenums simultaneously. This system would be used to control a three-dimensional flow field.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 119-142
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  • 86
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    Assessment of lift- and blockage-induced wall interference in a three-dimensional adaptive-wall tunnel (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A three-dimensional adaptive-wall wind tunnel experiment was conducted at Ames Research Center. This experiment demonstrated the effects of wall interference on the upwash distribution on an imaginary surface surrounding a lifting wing. This presentation demonstrates how the interference assessment procedure used in the adaptive-wall experiments to determine the wall adjustments can be used to separately assess lift- and blockage-induced wall interference in a passive-wall wind tunnel. The effects of lift interference on the upwash distribution and on the model lift coefficient are interpreted by a simple horseshoe vortex analysis.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 89-100
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  • 87
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    Wind tunnel wall interference in closed, ventilated and adaptive test sections (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A wall interference correction method for closed rectangular test sections was developed which uses measured wall pressures. Measurements with circular discs for blockage and a rectangular wing as a lift generator in a square closed test section validate this method. These measurements are intended to be a basis of comparison for measurements in the same tunnel using ventilated (in these case, slotted) walls. Using the vortex lattice method and homogeneous boundary conditions, calculations were performed which show sufficiently high pressure levels at the walls for correction purposes in test sections with porous walls. In Gottingen, an adaptive test section (which is a deformable rubber tube of 800 mm diameter) was built and a computer program was developed which is able to find the necessary wall adaptation for interference-free measurements in a single step. To check the program prior to the first run, the vortex lattice method was used to calculate wall pressure distributions in the nonadapted test section as input data for the one-step method. Comparison of the pressure distribution in the adapted test section with free-flight data shows nearly perfect agreement. An extension of the computer program can be made to evaluate the remaining interference corrections.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 61-78
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  • 88
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    Review of the advanced technology airfoil test program in the 0.3-meter transonic cryogenic tunnel (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: The following areas were addressed: interchangeable test sections in the 0.3-M Transonic Cryogenic Tunnel (TCT); typical airfoil installation; airfoil capability; advanced technology airfoil test (ATAT); effects of the Reynolds number on the normal force coefficient; effects of the Reynolds number on the drag coefficient; and comparison of experimental results with theory.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 361-374
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  • 89
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    Determination of equivalent model geometry for tunnel wall interference assessment/correction (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A formula for the determination of equivalent model geometry with two variables measured at the interface is derived, based on two dimensional subsonic flow. This predicted model profile is a reasonable initial estimate for transonic flow as long as the sonic region does not reach the interface. A general formula is given in two forms. One is in terms of complex variable functions and the other is an integral equation. The complex-function formula has the advantage of using analytic expressions. The integral equation form requires a numerical solution after assuming the model geometry as a polynomial function. Examples are given to illustrate the application of the formulas.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 335-342
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  • 90
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    An analytic solution to the classical two-body problem with drag (1981)
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    Publication Date: 2006-02-14
    Description: The two body problem was analyzed with a specific drag model. The model treats drag as a force proportional to the vector velocity and inversely proportional to the distance to the center of attraction. The solution is expressed in terms of known functions and is of a simple and compact form. The time of flight is expressed as a quadrature in the true anomaly. The results are: (1) development of a vector differential equation which allows analysis of an infinite number of gravitational and drag models; and (2) obtaining the solution of a linear differential equation using the inverse method of laplace transforms.
    Keywords: AERODYNAMICS
    Type: Houston Univ. The 1981 NASA ASEE Summer Fac. Fellowship Program, Vol. 2; 22 p
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  • 91
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    Wind tunnel wall interference correction for aircraft models (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Wall interference correction procedures seek to determine the required changes in certain flow or geometric parameters so that the difference between the flow properties at the model's surface in the tunnel and free air are minimized. A transonic and a linear correction procedure were developed for aircraft models. In addition to Mach number and angle of attack corrections, an estimate of the accuracy of the corrections is provided by the transonic correction procedure. Lift, pitching moment and pressure measurements near the tunnel walls are required. The efficiency and accuracy of the correction procedure are improved. Moreover, correction of both the wing and tail angles of attack is allowed. The procedure is valid for transonic as well as subcritical flows. However, for subcritical flows further approximations and simplifying assumptions are made, leading to a very simple and efficient correction procedure.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 301-322
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  • 92
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    Tunnel constraint for a jet in crossflow (1984)
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    Publication Date: 2006-02-14
    Description: A facet of a unified tunnel correction scheme which uses wall pressures to determine tunnel induced blockage and upwash is described. With this method, there is usually no need to use data concerning model forces or power settings to find the interference; it follows directly from the pressures and tunnel dimensions. However, highly inclined jets do not produce good pressure signatures and are highly three dimensional, so they must be treated differently. Flow modeling is also discussed.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 273-290
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  • 93
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    Progress in wind tunnel wall interference assessment/correction procedures at the NAE (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Wall corrections as a function of wall porosity in the transonic wall interference problem was assessed. Effective porosities primarily for the two dimensional case were established as follows: (1) comparison of experimental data for two geometrically similar models of different chord/height ratio, an overall value of wall porosity could be deduced; (2) theoretical development which allows for unequal porosity for the floor and ceiling and wall boundary pressure measurements, porosities for floor and ceiling could be deduced; (3) a scheme was developed which allowed unequal porosity of floor and ceiling and streamwise varying porosity. The boundary layer development along the perforated floor and ceiling under the influence of the model pressure field, variations in boundary layer thickness underlining the difficulties in deducing meaningful values of wall porosity were determined. Wall boundary pressure measurement, in combination with singularity modelling of the airfoil, was sufficient to yield required information on the wall interference flow without having to establish some value for wall porosity. The singularity modelling of the airfoil initially covered only lift and volume but was extended to include drag and pitching moment, and second order volume term. It is shown by asymptotic transonic small disturbance analysis, that the derived corrections to angle of attack and free stream Mach number are correct to the first order.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 231-257
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  • 94
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    Asymptotic methods for wind tunnel wall corrections at transonic speed (1984)
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    Description: The effort to develop classical methods to compute wall interference at transonic speeds is outlined. The two-dimensional theory and three-dimensional development are discussed. Also, some numerical application of the two-dimensional work are indicated. The basic advantages of the asymptotic theory are noted.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 193-203
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  • 95
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    Effect of boundary layers on solid walls in three-dimensional subsonic wind tunnels (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A solution for the tunnel wall boundary layer effects for three-dimensional subsonic tunnels is presented. The model potentials are represented with simple singularities placed on the centerline of the tunnel and Laplace's equation in cylindrical coordinates is solved for either the conventional homogeneous slotted-wall boundary condition, the solid-wall viscous boundary condition, or a combination of them. The most pronounced wall boundary layer effect is on solid blockage for completely closed wind tunnels. Boundary layers on the wall reduce the blockage from the solid-wall, no-boundary-layer case in a manner similar to opening slots in a solid wall. Additionally, for solid-wall tunnel configurations, the streamline curvature interference factor is reduced by a significant amount, whereas the lift interference factor at the model station does not depend on the boundary layer parameter. For combination wall configurations, the slot effect of the horizontal walls dominates the viscous effect of the solid sidewalls.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 205-218
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  • 96
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    Experiments suitable for wind tunnel wall interference assessment/correction (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: Three experiments suitable for wall interference assessment and evaluation of proposed correction methods are presented. The experiments are: (1) a series of airfoil tests using a newly designed transonic flow facility that employs side-wall boundary layer suction and upper- and lower-wall shaping; (2) tests on a swept airfoil section spanning a solid-wall wind tunnel with fixed contouring on all four walls; and (3) tests on a swept wing of aspect ratio 3 mounted in a solid-wall wind tunnel with fixed flat walls. Each of the experiments provides data on the airfoil sections as well as on the wind tunnel walls. All the experiments were performed in solid wall wind tunnels corrected for boundary layer displacement effects. Although the experiments were performed primarily to evaluate computer code performance, it is believed that they also provide information that can be used to evaluate methods for assessing and correcting wall interference effects.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 171-190
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  • 97
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    Effect of upstream sidewall boundary layer removal on an airfoil test (1984)
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    Publication Date: 2006-02-14
    Description: Sidewall boundary layer effects were investigated by applying partial upstream sidewall boundary layer removal in the Langley 0.3-m transonic cryogenic tunnel. Over the range of sidewall boundary layer displacement thickness of these tests the influence on pressure distribution was found to be small for subcritical conditions; however, for supercritical conditions the shock position was affected by the sidewall boundary layer. For these tests (with and without boundary layer remove) comparisons with predictions of the GRUMFOIL computer code indicated that Mach number corrections due to the sidewall boundary layer improve the agreement for both subcritical and supercritical conditions. The results also show that sidewall boundary layer removal reduces the magnitude of the sidewall correction; however, a suitable correction must still be made.
    Keywords: AERODYNAMICS
    Type: Wind Tunnel Wall Interference Assessment and Correction, 1983; p 143-163
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  • 98
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    A data base for three-dimensional all-interference code evaluation (1984)
    In:  CASI
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    Publication Date: 2006-02-14
    Description: A validation of a measured boundary condition technique was carried out to demonstrate the feasibility of a wall interference assessment/correction (WIAC) system. An experimental evaluation was also carried out to compare performances of various techniques, to define the number of necessary boundary measurements for accurate assessment/corrections and to define the envelope of test conditions for which accurate assessment/corrections are achieved. The relative merits of a WIAC system and an adaptive wall tunnel are compared. The measurement surface boundary data is performed with a system of two rotating pipes. These pipes sweep out a cylindrical measurement surface near the tunnel walls, approximately one inch from the wall at the closest point. The experimental model was specially designed and fabricated for the adaptive wall experiments. The model is a wing/tail/body configuration with swept lifting surface. The boundary data taken in Tunnel 1T with the rotating pipe system has been shown to offer several attractive features for WIAC code evaluation. Good spatial resolution of measurements is achieved and measurements are made upstream and downstream of the model. Also, two velocity components are determined.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 101-118
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  • 99
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    Survey of ONERA activities on adaptive-wall applications and computation of residual corrections (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: The research undertaken concerning the computation and/or reduction of wall interference follows two main axes: improvement of wall correction determinations, and use of adaptive flexible walls. The use of wall-measured data to compute interference effects is reliable when the model representation is assessed by signatures with known boundary conditions. When the computed interferences are not easily applicable to correcting the results (especially for gradients in two-dimensional cases), the flexible adaptive walls in operation in T2 are an efficient and assessed means of reducing the boundary effects to a negligible level, if the direction and speed of the flow are accurately measured on the boundary. The extension of the use of adaptive walls to three-dimensional cases may be attempted since the residual corrections are assumed to be small and are computable.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center Wind Tunnel Wall Interference Assessment and Correction, 1983; p 43-60
    Format: text
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    Langley high-lift research on a high-aspect-ratio supercritical wing configuration (1981)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: To determine the low speed performance characteristics of a representative high aspect ratio supercritical wing, two low speed jet transport models were fabricated. A 12-ft. span model was used for low Reynolds number tests in the Langley 4- by 7-Meter Tunnel and the second, a 7.5-ft. span model, was used for high Reynolds number tests in the Ames 12-foot Pressure Tunnel. A brief summary of the results of the tests of these two models is presented and comparisons are made between the data obtained on these two models and other similar models. Follow-on two and three dimensional research efforts related to the EET high-lift configurations are also presented and discussed.
    Keywords: AERODYNAMICS
    Type: Advan. Aerodyn.: Selected NASA Res.; p 55-77
    Format: text
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    NASA TECHNICAL REPORTS
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