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  • 1
    Electronic Resource
    Electronic Resource
    Small dc motor for producing motion in a cryogenic environment, and a method for monitoring its orientation (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 814-820 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In the field of condensed matter physics, it is frequently necessary to produce motion at low temperatures. While this can often be done using a mechanical linkage which connects the cryogenic and ambient environments, space constraints sometimes render such a solution impractical. The following paper describes a miniature dc electric motor which can be used to produce motion under these conditions, and also presents a novel scheme for monitoring its position. The motor is a skew-wound ironless device with a coaxial gearhead, and is capable of operating at a temperature of 4 K, in a vacuum, and in a magnetic field of several hundred gauss. The position monitoring arrangement requires no modifications to the motor or the addition of extra hardware, such as rotary encoders or potentiometers. Based on the angular dependence of the rotor inductance, it has been found to work with a number of different motors of the skew-wound ironless type, both at room temperature and at 4°. Provisions have been made to allow the motor and position monitor to be operated by computer control. The author anticipates that they will find applications in other areas where motion is needed and space is at a premium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144165
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  • 2
    Electronic Resource
    Electronic Resource
    Pilot-Plant Trials on River Dee Water at Huntington (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 7 (1993), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: A pilot plant which has been used to examine the suitability of a number of treatment options for upgrading North West Water's water-treatment plant at Huntingdon, Chester, is described. Processes tested include biological pretreatment using a fluidized sand bed to remove manganese and ammonia, chemical coagulation, chemical oxidation using chlorine, ozone and potassium permanganate, and both primary and secondary filtration with sand and granular activated carbon. The reduction of trihalomethanes and pesticides was also investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1993.tb00854.x
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  • 3
    Electronic Resource
    Electronic Resource
    Spatial organization and population density of the fish community of the litter banks within a central Amazonian blackwater stream (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 37 (1990), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Results of a study of the fish community of the leaf litter banks in the lower reaches of the Taruma-Mirim, a small central Amazonian stream is presented. The Taruma-Mirim is an acidic, blackwater, forest stream which flows through igapo forest and enters the Rio Negro close to Manaus. The commonly held view that these blackwaters hold an impoverished ichthyofauna is challenged. The studied litter banks hold about 20 species of fish, all of which were found to live within distinct subregions of the habitat. Average fish density was about 100 individuals m−2. Absolute population sizes were found to be remarkably small; within a 200 m2 area the most abundant species had a population size of about 104 and the least abundant 〈102 individuals. It is argued that high species richness linked to specialized habitat requirements and small population size indicates considerable population stability. The factors leading to the evolution of such species richness are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1990.tb05871.x
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  • 4
    Electronic Resource
    Electronic Resource
    Stovall, FloydGraham, KennethGalloway, DavidCarlson, Eric W.Regan, Robert: The Poems of Edgar Allan PoeEdgar Allan Poe: Selected TalesSelected Writings of Edgar Allan PoeThe Recognition of Edgar Allan PoePoe: A Collection of Critical Essays : Charlottesville, Va., University of Virginia Press, 1965London, Oxford University Press, 1967Harmondsworth, Penguin Books, 1967Ann Arbor, University of Michigan Press, 1966Englewood Cliffs, N.J., Prentice-Hall, 1967 (1968)
    Cambridge : Cambridge University Press
    Journal of American studies 2 (1968), S. 143-145 
    Details
    ISSN: 0021-8758
    Source: Cambridge Journals Digital Archives
    Topics: English, American Studies , History , Political Science , Sociology , Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1017/S0021875800010069
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  • 5
    Electronic Resource
    Electronic Resource
    Ideas in theoretical biology Why legs and not wheels? (1991)
    Springer
    Acta biotheoretica 39 (1991), S. 151-155 
    Details
    ISSN: 1572-8358
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The inanimate world, including Man's wheeled vehicles, follow the classical mechanical laws: trajectories of objects in phase-space are predictable on the basis of the vectors of forces acting on the objects. Animal locomotion does not involve wheels, but relies on antagonistic contractile fibre systems, and defies prediction of trajectories. These features are tied up with the faculty of “immediate steering” in response to momentaneous physiological and environmental stimuli. Thus, animal motor systems have two relatively independent inputs: the sensory/information system, which is the cause for specific trajectories, and the “erfolg system” which permits for the execution of the thus instructed motion. The problem of relative energetic magnitudes between the two systems — in that the causative system involves small, yet the executive system large energies — is specially considered in relation to locomotion by antagonistically functioning mechanical elements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046597
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  • 6
    Electronic Resource
    Electronic Resource
    Minding the Emperor's new mind (1994)
    Springer
    Acta biotheoretica 42 (1994), S. 77-84 
    Details
    ISSN: 1572-8358
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This essay equates Penrose's (1989) ‘Emperor’ with the scientist engaging in mental (Schrödinger's ‘cat’) or real experiments. The simultaneous presence of apparently contradictory phase-spatial symmetry conditions on the various hierarchical levels of biological systems are seen as the result of genetic and neurophysiological information that interferes with the physico-chemical vectors between the structural components of the system, the ‘experimenter’ being an integral part of this informational causality. Equations pertaining to the lowest structural levels of matter, therefore, may not be extendable over higher levels of biological organization, including human science and technology, which are seen as part and parcel of biology. This situation calls for a formal ‘theoretical biophysics’ which concentrates on macroscopic processes where life and, above all,Homo sapiens, is involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00706841
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  • 7
    Electronic Resource
    Electronic Resource
    Competition and information (1993)
    Springer
    Acta biotheoretica 41 (1993), S. 249-266 
    Details
    ISSN: 1572-8358
    Keywords: Competition theory ; Volterra ; information in competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Reconsideration of the logistic equation and of its expansion to the special and general Volterra competition equations in terms of mass/energy in phase-space, shows that information on the phase-spatial conditions of resource and consumers determines specific population parameters which, in turn, decide on coexistence and extinction. Thus, introduction ofInformation as a separate and independent biophysical parameter, in analogy, and in addition, to Force in Classical Physics, is necessary. This allows for quantification of informational effects on resource flows and population numbers. As such, different population growth dN/dt during a competitive exclusion process, is theeffect of competition, and not itscause. It is found that species recognition of “self” and ignorance of other consumers and of their phase-spatial conditions of resource supplies stabilizes coexistence, while excess information on competitors and on resource supplies destabilizes community structure. These findings are particularly relevant for the speciesHomo sapiens. Among other, apparently disparate population phenomena, Information as a causative parameter also resolves the controversy of “complexity and stability” in biological systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712171
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  • 8
    Electronic Resource
    Electronic Resource
    The pattern of population growth as a function of redundancy and repair (1990)
    Springer
    Acta biotheoretica 38 (1990), S. 83-90 
    Details
    ISSN: 1572-8358
    Keywords: biological repair ; genetic repair ; evolution of sexual reproduction ; population stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A basic model of hierarchical structure, expressed by simple, linear differential equations, shows that the pattern of population growth is essentially determined by conditions of redundancy in the sub-structure of individuals. There does not exist any possible combination between growth rate and accident rate that could balance population numbers and/or the level of redundancy within the population; all possible combinations either lead to extinction or to positive population growth with a decline of the fraction of individuals with redundant substructure. Declining populations, however, can be held fluctuating between certain limits by periodic phases of sub-unit repair. These results are particularly pertinent to the population dynamics of diploid (polyploid) organisms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047545
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  • 9
    Electronic Resource
    Electronic Resource
    Climatic and limnological changes associated with the Younger Dryas in Atlantic Canada (1993)
    Springer
    Climate dynamics 8 (1993), S. 177-187 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Pollen, diatom and chironomid fossils from the sediments of a core from Brier Island Bog Lake, Nova Scotia were studied in an attempt to relate changes in microfossil composition to a climatic cooling in Atlantic Canada correlative with the European Younger Dryas ca. 10 to 11 ka. Our paleolimnological data were then compared to similar types of data from Splan Pond, New Brunswick to determine if there were any significant differences between a coastal and a more inland site. Nonarboreal pollen was dominant throughout the Brier Island core and the interval 10.0–11.0 ka did not show the typical decline in Picea and increases in tundra-like vegetation characteristic of many sites in Atlantic Canada. However, the limnological indicators did undergo marked changes in taxon composition. The chironomid assemblage was initially dominated by shallow-water, warm-adapted chironomid taxa followed by abundant Sergentia (a cold stenotherm) during 10–11 ka. Sergentia disappeared in the “post Younger Dryas” interval and the warm-adapted genera resumed dominance. Chironomid-inferred paleotemperature reconstructions revealed that at both Brier Island Bog Lake and Splan Pond, summer surface-water temperatures dropped abruptly to between 13 and 17°C during the 10–11 ka interval, suggesting that a cooler climate was present in Atlantic Canada correlative with the European Younger Dryas. Diatom assemblage changes during the same period corroborate the occurrence of limnological fluctuations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00207964
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  • 10
    Electronic Resource
    Electronic Resource
    The larva and habitat ofParakiefferiella nigra Brundin (Diptera: Chironomidae) (1992)
    Springer
    Aquatic ecology 26 (1992), S. 527-531 
    Details
    ISSN: 1573-5125
    Keywords: palaeolimnology ; Chironomidae ; taxonomy ; larval subfossils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Collections of adults ofParakiefferiella nigra Brundin indicate that this chironomid occurs widely in arctic and subarctic zones. In addition, it has occasionally been collected in cool temperate and boreal forest lakes of both North America and Europe. Although widely distributed, the larva and its habitat have not previously been described. Identity of the larva ofP. nigra has been established by studying associated reared specimens. The distinctive larva, with reduced second lateral mental teeth, is stenotopic, and on the basis of modern collections appears to be most abundant in cold, oligotrophic lakes. More data is required to establish the range of thermal environments inhabited by the larva. Larval head capsule remains ofP. nigra are common in late-glacial sediments of southwestern British Columbia lakes and provide important evidence for oligotrophic conditions during late-glacial time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02255286
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