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  • evolution  (41)
  • stability  (40)
  • Springer  (81)
  • Annual Reviews
  • Blackwell Publishing Ltd
  • 2005-2009
  • 1990-1994  (81)
  • 1980-1984
  • 1955-1959
  • 1992  (81)
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  • 2005-2009
  • 1990-1994  (81)
  • 1980-1984
  • 1955-1959
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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of stable matchings as extreme points of a polytope (1992)
    Springer
    Mathematical programming 54 (1992), S. 57-67 
    Details
    ISSN: 1436-4646
    Keywords: Matchings ; stability ; extreme points ; polytope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract The purpose of this paper is to extend a modified version of a recent result of Vande Vate (1989) which characterizes stable matchings as the extreme points of a certain polytope. Our proofs are simpler and more transparent than those of Vande Vate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01586041
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  • 2
    Electronic Resource
    Electronic Resource
    Phthalocyanine-containing polymers (1992)
    Springer
    Journal of inorganic and organometallic polymers and materials 2 (1992), S. 79-85 
    Details
    ISSN: 1572-8870
    Keywords: Phthalocyanines ; polymers ; siloxanes ; conductivity ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The author's work on the incorporation of phthalocyanines into inorganic polymers is reviewed. The synthesis of poly(siloxane phthalocyanines) and the synthesis and characterization of fluoro(phthalocyanine) Group III compounds and their conducting derivatives are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696537
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  • 3
    Electronic Resource
    Electronic Resource
    Analytical relationships between the ionization of 1,3-dicarbonylic ligands and stability of their Cr(III), Ni(II), Co(II) and Cu(II) 1∶1 chelates (1992)
    Springer
    Journal of solution chemistry 21 (1992), S. 1145-1152 
    Details
    ISSN: 1572-8927
    Keywords: Chromium(III) ; β-diketones ; β-diketonates ; chelation ; complexation ; correlation ; stability ; equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It has been demonstrated that the logarithm of the stability constant of some monochelated chromium(III) compounds, with structurally similar 1,3-dicarbonylic species, is linearly related to the negative logarithm of the acid ionization constant of the ligand. Graphical and analytical correlations which could be useful in predicting equilibrium constants of chromium(III)-β-diketonates, as well as other first-row transition metal derivatives, have been developed. A quantitative evaluation of the complexes stability has been carried out, providing information about the effects of ligand substituents on the equilibrium constants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00651860
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  • 4
    Electronic Resource
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    Interval stability and interval covering property in finite posets (1992)
    Springer
    Order 9 (1992), S. 163-175 
    Details
    ISSN: 1572-9273
    Keywords: Primary 06A07 ; secondary 05C70 ; Partial order ; interval ; stability ; covering ; Sperner property ; symmetric chains ; NP-completeness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Given a finite ranked posetP, let α(P) be the maximum size of a subset ofP such that no two elements of it belong simultaneously to some interval ofP and let ϱ(P) be the minimum number of intervals covering all elements ofP. We say thatP has the strong interval stability property (resp. the strong interval covering property) if for each subposetP′ induced by consecutive levels ofP, i.e.,P′=P (l)∪...∪P (u), one has α(P′)=max{|P (l)|, |P (u)|} (resp. ϱ(P′)=max{|P (l)|, |P (u)|}). We prove these properties for several classes of posets and discuss some general facts concerning the numbers α(P) and ϱ(P), e.g., NP-completeness and min-max relations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00814408
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  • 5
    Electronic Resource
    Electronic Resource
    Stationary waiting time derivatives (1992)
    Springer
    Queueing systems 12 (1992), S. 369-389 
    Details
    ISSN: 1572-9443
    Keywords: Perturbation analysis ; stability ; stochastic difference equations ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We investigate the stability of waiting-time derivatives when inputs to a queueing system-service times and interarrival times-depend on a parameter. We give conditions under which the sequence of waiting-time derivatives admits a stationary distribution, and under which the derivatives converge to the stationary regime from all initial conditions. Further hypotheses ensure that the expectation of a stationary waiting-time derivative is, in fact, the derivative of the expected stationary waiting time. This validates the use of simulation-based infinitesimal perturbation analysis estimates with a variety of queueing processes. We examine waiting-time sequences satisfying recursive equations. Our basic assumption is that the input and its derivatives are stationary and ergodic. Under monotonicity conditions, the method of Loynes establishes the convergence of the derivatives. Even without such conditions, the derivatives obey a linear difference equation with random coefficients, and we exploit this fact to find stability conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01158809
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  • 6
    Electronic Resource
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    Stability of token passing rings (1992)
    Springer
    Queueing systems 11 (1992), S. 7-33 
    Details
    ISSN: 1572-9443
    Keywords: Token passing rings ; stability ; substability ; ergodicity ; Markov chains ; Loynes' scheme ; stochastically dominant ; Little's formula ; regenerative processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A sufficient stability condition for the standard token passing ring has been “known” since the seminal paper by Kuehn in 1979. However, this condition was derived without formal proof, and the proof seems to be of considerable interest to the research community. In fact, Watson observed that in the performance evaluation of token passing rings, “it is convenient to derive stability conditions ... (without proof)”. Our intention is to fill this gap, and to provide a formal proof of thesufficient and necessary stability condition for the token passing ring. In this paper, we present the case when the arrival process to each queue is Poisson but service times and switchover times are generally distributed. We consider in depth a gatedl-limited (l≤ ∞) service discipline for each station. We also indicate that the basic steps of our technique can be used to study the stability of some other multiqueue systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01159285
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  • 7
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    Stable steady state of some population models (1992)
    Springer
    Journal of dynamics and differential equations 4 (1992), S. 161-190 
    Details
    ISSN: 1572-9222
    Keywords: Delay differential equations ; equilibrium ; stability ; limiting equations ; population dynamics ; 34K20 ; 34K25 ; 92A15
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Applying an analytical method and several limiting equations arguments, some sufficient conditions are provided for the existence of a unique positive equilibriumK for the delay differential equationx=−γx+D(x t ), which is the general form of many population models. The results are concerned with the global attractivity, uniform stability, and uniform asymptotic stability ofK. Application of the results to some known population models, which shows the effectiveness of the methods applied here, is also presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048159
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  • 8
    Electronic Resource
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    Stability estimates in inverse scattering (1992)
    Springer
    Acta applicandae mathematicae 28 (1992), S. 1-42 
    Details
    ISSN: 1572-9036
    Keywords: 35R30 ; Inverse scattering ; stability ; noisy data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract An algorithm is given for calculating the solution to the 3D inverse scattering problem with noisy discrete fixed energy data. The error estimates for the calculated solution are derived. The methods developed are of a general nature and can be used in many applications: in nondestructive evaluation and remote sensing, in geophysical exploration, medical diagnostics, and technology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00047029
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  • 9
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    A new interpolation procedure for adapting Runge-Kutta methods to delay differential equations (1992)
    Springer
    BIT 32 (1992), S. 634-649 
    Details
    ISSN: 1572-9125
    Keywords: AMS(MOS): 65L20 ; CR: 5.17 ; delay differential equations ; numerical solution ; Runge-Kutta methods ; interpolation procedures ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper deals with adapting Runge-Kutta methods to differential equations with a lagging argument. A new interpolation procedure is introduced which leads to numerical processes that satisfy an important asymptotic stability condition related to the class of testproblemsU′(t)=λU(t)+μU(t−τ) with λ, μ ε C, Re(λ)〈−|μ|, and τ〉0. Ifc i denotes theith abscissa of a given Runge-Kutta method, then in thenth stept n−1→t n :=t n−1+h of the numerical process our interpolation procedure computes an approximation toU(t n−1+c i h−τ) from approximations that have already been generated by the process at pointst j−1+c i h(j=1,2,3,...). For two of these new processes and a standard process we shall consider the convergence behaviour in an actual application to a given, stiff problem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01994847
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  • 10
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    On a class of variational equations transformable to the Gauss hypergeometric equation (1992)
    Springer
    Celestial mechanics and dynamical astronomy 53 (1992), S. 145-150 
    Details
    ISSN: 1572-9478
    Keywords: Monodromy matrix ; Gauss hypergeometric equation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A new class of linear ordinary differential equations with periodic coefficients is found which can be transformed to the Gauss hypergeometric equation, and therefore the monodromy matrices are computable explicitly. These equations appear as the variational equations around a straight-line solution in Hamiltonian systems of the form H = T(p) + V(q), where T(p) and V(q) are homogeneous functions of p and q, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00049462
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  • 11
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    Effects of small external forces on the planar oscillation of a cable connected satellites system (1992)
    Springer
    Celestial mechanics and dynamical astronomy 53 (1992), S. 219-226 
    Details
    ISSN: 1572-9478
    Keywords: Artificial satellite ; dissipative forces ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effects of small external dissipative and disturbing forces on the non-linear planar oscillation of a cable connected satellites system in the central gravitational field of earth have been studied. Typical non-linear oscillation's phenomena arizing from the aforesaid external forces are shown to take place. The presence of these forces enables the application of asymptotic methods of the theory of non-linear oscillations due to Bogoliubov and Mitropolsky to the equation characterizing the non-linear oscillation of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00052610
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  • 12
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    Presence of a partial urea cycle in the leech,Poecilobdella granulosa (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 729-731 
    Details
    ISSN: 1420-9071
    Keywords: Urea cycle ; leech ; botryoidal tissue ; hirudineans ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Ornithine carbamoyltransferase (OCT) and arginase, but not arginine synthetase (AS), were detected in the body wall and gut tissues of the leech. The activities of these enzymes were not altered by starvation. The high activity of arginase in body wall is probably due to the association of the latter with botryoidal tissue. Hirudineans, which evolved from oligochaete ancestors, appear to have lost the citrulline-arginine segment of the urea cycle due to their ammonotelic mode of nitrogen excretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02124288
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  • 13
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    Life and teleology (1992)
    Springer
    Journal for general philosophy of science 23 (1992), S. 85-103 
    Details
    ISSN: 1572-8587
    Keywords: life ; teleology ; evolution ; reality ; representation ; experience
    Source: Springer Online Journal Archives 1860-2000
    Topics: Philosophy , Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Summary A comprehensive definition of the phenomenon called “life” led to the addition of many dimensions to the natural sciences, and especially the conscious mental dimension. Historical attention is paid not only to those employing the natural philosophical paradigms, but also to evolutionary theories and to the Kantian teleological philosophy. The belief that science can solve the riddle of life is a category of purposal thinking. A revised version of critical teleology is essential for comprehension of life.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01801797
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  • 14
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    Real-time feedback scheduling of flexible manufacturing systems (1992)
    Springer
    Journal of intelligent and robotic systems 6 (1992), S. 51-63 
    Details
    ISSN: 1573-0409
    Keywords: Scheduling ; flexible manufacturing systems ; stability ; feedback
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A genetic manufacturing environment is considered. The emphasis is on small-lot, discrete, and asynchronous type of manufacturing systems rather than high volume and continuous type. Two classes of scheduling policies are proposed to render the machine stable. The policies are of feedback type. The decision is made in real-time and on-line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314697
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  • 15
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    Force control of robots with nonlinearities (1992)
    Springer
    Journal of intelligent and robotic systems 6 (1992), S. 219-240 
    Details
    ISSN: 1573-0409
    Keywords: Force control ; slip-stick friction ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper explores two practical issues related to the force control of manipulators. The first issue examined is how system stability is effected by commonly occurring manipulator nonlinearities, such as sampled-data, control signal saturation and slip-stick friction. It is shown that discretely implemented force control algorithms can drive the feedback force controlled manipulator into a limit cycle, even for a very small sampling period that by far satisfies Shannon's sampling theorem. The bounds of stability are enhanced by the presence of control signal saturation and slip stick friction. The second issue investigated is the inclusion of a high gain inner position loop as a means to minimize the unpredictability in the steady state error due to slip-stick friction. In order to support the theoretical conclusions, experiments were performed with the PUMP 560 industrial robot testbed facility developed at Colorado State University.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00248017
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  • 16
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    A structural approach to robust stability of polynomials (1992)
    Springer
    Multidimensional systems and signal processing 3 (1992), S. 421-425 
    Details
    ISSN: 1573-0824
    Keywords: Convex combination ; polynomial ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract A sufficient condition for Hurwitz stability of a convex combination of two stable polynomials is obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01940234
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  • 17
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    Fertilizer value of pig slurries processed by the Promest procedure (1992)
    Springer
    Nutrient cycling in agroecosystems 32 (1992), S. 61-70 
    Details
    ISSN: 1573-0867
    Keywords: Pig slurry ; processing ; relative efficiency index ; N ; P ; K ; organic carbon ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In the Netherlands, pig slurries are processed to improve their fertilizer value as well as handling and application. The relative efficiency index (REI) of N, P and K and the stability of organic carbon (C) in test products of processed pig slurries (PPS) were determined in pot and incubation experiments. The dry and easily manageable PPS were produced according to the Promest procedure. The mineral fraction of total N varied from 60 to 88%. It consisted mainly of nitrate. About 25% of the organic N was rapidly mineralized. The REI of N varied from 66 to 92%. After application REI of P from pelletized PPS varied from 41 to 62% in the first half year. The REI of P in ground but non-pelletized PPS varied from 81 to 100%. The REI of K was estimated to be 100%. PPS contained less easily decomposable organic C than untreated pig slurry due to the anaerobic digestion step in the processing procedure. About 34% of the organic C disappeared as methane and carbon dioxide during processing. It was concluded that processing improved the fertilizer value of PPS compared with that of untreated pig slurry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054395
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  • 18
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    Metabolic pathways inParacoccus denitrificans and closely related bacteria in relation to the phylogeny of prokaryotes (1992)
    Springer
    Antonie van Leeuwenhoek 61 (1992), S. 1-33 
    Details
    ISSN: 1572-9699
    Keywords: Paracoccus denitrificans ; denitrification ; methylotrophy ; cytochromec ; cytochrome oxidase ; phylogeny ; evolution ; lateral gene transfer ; nitrogen fixation ; Thiosphaera pantotropha
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Denitrification and methylotrophy inParacoccus denitrificans are discussed. The properties of the enzymes of denitrification: the nitrate-nitrite antiporter, nitrate reductase, nitrite reductase, nitric oxide reductase and nitrous oxide reductase are described. The genes for none of these proteins have yet been cloned and sequenced fromP. denitrificans. A number of sequences are available for enzymes fromEscherichia coli, Pseudomonas stutzeri andPseudomonas aeruginosa. It is concluded that pathway specificc-type cytochromes are involved in denitrification. At least 40 genes are involved in denitrification. In methanol oxidation at least 20 genes are involved. In this case too pathway specificc-type cytochromes are involved. The sequence homology between the quinoproteins methanol dehydrogenase, alcoholdehydrogenase and glucose dehydrogenase is discussed. This superfamily of proteins is believed to be derived from a common ancestor. ThemoxFJGI operon determines the structural components of methanol dehydrogenase and the associatedc-type cytochrome. Upstream of this operon 3 regulatory proteins were found. The mox Y protein shows the general features of a sensor protein and the moxX protein those of a regulatory protein. Thus a two component regulatory system is involved in both denitrification and methylotrophy. The phylogeny of prokaryotes based on 16S rRNA sequence is discussed. It is remarkable that the 16S rRNA ofThiosphaera pantotropha is identical to that ofP. denitrificans. Still these bacteria show a number of differences.T. pantotropha is able to denitrify under aerobic circumstances and it shows heterotrophic nitrification. Nitrification and heterotrophic nitrification are found in species belonging to the β-and γ-subdivisions of purple non-sulfur bacteria. Thus the occurrence of heterotrophic nitrification inT. pantotropha which belongs to the α-subdivision of purple non-sulfur bacteria is a remarkable property. FurthermoreT. pantotropha contains two nitrate reductases of which the periplasmic one is supposed to be involved in aerobic denitrification. The nitrite reductase is of the Cu-type and not of the cytochromecd 1 type as inP. denitrificans. Also the cytochromeb of theQbc complex ofT. pantotropha is highly similar to its counterpart inP. denitrificans. It is hypothesized that the differences between these two organisms which both contain large megaplasmids is due to a combination of loss of genetic information and plasmid-coded properties. The distribution of a number of complex metabolic systems in eubacteria and in a number of species belonging to the α-group of purple non sulphur bacteria is reviewed. Two possibilities to explain this haphazard distribution are considered: 1. Lateral gene transfer between distantly related micro organisms occurs frequently. 2. The eubacterial ancestors must have possessed already these properties. The distribution of these properties is due to sporadic loss during evolutionary divergence. With respect to the occurrence and frequency of lateral gene transfer two opposing views exist. According to molecular biologists lateral gene transfer occurs frequently and is very easy. Bacteria are supposed to form one large gene pool. On the other hand population geneticists have provided evidence that strong systems operate that establish reproductive isolation between diverged species and even between closely related cell lines. Data on amino acid sequences of nitrogenase proteins, cytochromesc, cytochrome oxidases, β-subunits of ATP synthase and tryptophan biosynthetic enzymes of various micro organisms were reviewed. In all these cases phylogenetic trees could be constructed based on the amino acid sequence data. In all cases this phylogenetic tree was similar to the one based on 16S rRNA homology. Only in one case evidence for the occurrence of lateral gene transfer was obtained. Therefore it is concluded that lateral gene transfer played a minor role in the distribution of complex metabolic systems among prokaryotes. It must be stressed that this does not exclude the possibility that lateral gene transfer occurred frequently in the initial stage of bacterial evolution. It is hypothesized that the appearance of nitrogen fixation, denitrification and cytochrome oxidase formation were early events in the evolution of micro organisms. Both systems are supposed to have evolved only once. Subsequently the capacity to fix nitrogen or to denitrifymust have been lost many times, just as photosynthetic capacity is supposed to have been lost many times. During evolution many systems have been lost leading to a haphazard distribution of metabolic characters among bacteria. As an example it is suggested that organisms with a respiratory chain similar to that ofEscherichia coli arose by loss of the capacity to form the Qbc complex andc-type cytochromes. The remaining systems could be controlled much better however than in the ancestral organisms.
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    URL: http://dx.doi.org/10.1007/BF00572119
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  • 19
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    Development of non-reproductive castes in the neotropical termite generaCornitermes, Embiratermes andRhynchotermes (Isoptera, Nasutitermitinae) (1992)
    Springer
    Insectes sociaux 39 (1992), S. 313-324 
    Details
    ISSN: 1420-9098
    Keywords: Isoptera ; Termitidae ; Nasutitermitinae ; caste differentiation ; phylogeny ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The developmental pattern of the neuter castes was studied in the mandibulate nasute generaCornitermes, Embiratermes andRhynchotermes. InCornitermes walkeri, all the workers and soldiers are male. There are two larval and a single worker instar. Workers can molt into presoldiers. InEmbiratermes chagresi andRhynchotermes perarmatus, both sexes are present among the neuters. A slight sexual dimorphism (males 〉 females) is discernible among both larval instars and among workers ofE. chagresi; female workers can molt into presoldiers. InR. perarmatus, the sexual dimorphism is conspicuous from the first larval instar on. Male larvae go through two instars, then give rise to workers, which do not molt. InR. perarmatus, there is no worker stage in females, but a third larval instar, preceding the presoldier. Hypotheses are proposed as to the evolution of these caste patterns, attempting to conciliate present knowledge of Nasutitermitinae phylogeny and known evolutionary trends affecting termite caste patterns, according to the species' ecology.
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    URL: http://dx.doi.org/10.1007/BF01323951
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  • 20
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    Social organization in some primitive Australian ants. I.Nothomyrmecia macrops Clark (1992)
    Springer
    Insectes sociaux 39 (1992), S. 425-438 
    Details
    ISSN: 1420-9098
    Keywords: Formicidae ; Nothomyrmecia ; evolution ; sociogram ; ethogram ; recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Results of laboratory-based ethological studies on twoNothomyrmecia macrops colonies with individually marked workers are reported. Interactive behavioural acts constituted less than 1% of all those recorded, revealing a strong tendency by the ants not to engage in social contact. Very few workers performed queen-directed acts. They stayed near the queen, though seldom in direct contact. Division of labour was otherwise barely apparent, except that some individuals showed a propensity to guard the nest entrance. No exchange of food was observed between workers, workers and queen, or adults and larvae (apart from worker placement of prey items with larvae). A queen fed from aDrosophila carcass retrieved from the nest floor, without assistance from workers. Systematic scanned observations confirmed levels of inactivity higher than previously observed in ants (comprising almost 2/3 of recorded behavioural acts). The time budget for activities directed toward the immature stages was the same in both colonies, and fluctuated during the circadian period. Non-nestmate larvae added to worker groups were more frequently licked than nestmate larvae, but this might not involve the particular recognition of nestmateversus non-nestmate brood. These observations support the hypothesis thatNothomyrmecia is primitively eusocial, and of special significance in myrmecology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240625
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  • 21
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    Endogenous synthesis of peptidoglycan in eukaryotic cells; a novel concept involving its essential role in cell division, tumor formation and the biological clock (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 921-931 
    Details
    ISSN: 1420-9071
    Keywords: Biological clock ; cell division cycle ; diaminopimelate ; evolution ; FSu ; lysine ; muramate ; muramyl dipeptide ; peptidoglycan ; sleep muropeptide ; tumor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Degradation products of peptidoglycan, the universal bacterial cell wall constituent, were previously found in animal tissues and urine. Reassessment and quantitative analysis of available data lead to an original concept, i.e. that eukaryotic cells synthesize peptidoglycan. We present a model in which this endogenously synthesized peptidoglycan is essential for the processes of eukaryotic cell division and sleep induction in animals. Genes for peptidoglycan metabolism, like those for lysine biosynthesis in plants, are probably inherited from endosymbiotic bacteria, the ancestors of mitochondria and chloroplasts. Corollaries of this concept, i.e. roles for peptidoglycan metabolism in tumor formation and in the biological clock, are supported by abundant evidence. We propose that many interactions between bacteria and eukaryotes are conditioned by their common genetic heritage.
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    URL: http://dx.doi.org/10.1007/BF01919139
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  • 22
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    The Light Green Cells ofLymnaea: A neuroendocrine model system for stimulus-induced expression of multiple peptide genes in a single cell type (1992)
    Springer
    Cellular and molecular life sciences 48 (1992), S. 464-473 
    Details
    ISSN: 1420-9071
    Keywords: Molluscan insulin-related peptides ; schistosomin ; neuropeptide gene family ; generation of neuropeptide diversity ; stimulus-dependent expression ; information-handling capacity ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We review recent experiments showing that the cerebral neuroendocrine Light Green Cells (LGCs) of the freshwater snail,Lymnaea stagnalis, express a family of distinct though related molluscan insulin-related peptide (MIP) genes. The LGCs are involved in the regulation of a wide range of interrelated life processes associated with growth, (energy) metabolism and reproduction. We consider the mechanism of generation of diversity among MIPs, and present evidence that conditions with distinct effects on growth, metabolism and reproduction also can induce distinct patterns of expression of the MIP and schistosomin genes. The stimulus-dependent expression of multiple neuropeptide genes enormously increases the adaptive potential of a peptidergic neuron. We suggest that this contributes significantly to the information-handling capacity of the brain.
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    URL: http://dx.doi.org/10.1007/BF01928165
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    A reinforcement connectionist approach to robot path finding in non-maze-like environments (1992)
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    Machine learning 8 (1992), S. 363-395 
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    ISSN: 0885-6125
    Keywords: Connectionism ; reinforcement learning ; robot path finding ; stability ; reactive systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper presents a reinforcement connectionist system which finds and learns the suitable situation-action rules so as to generate feasible paths for a point robot in a 2D environment with circular obstacles. The basic reinforcement algorithm is extended with a strategy for discovering stable solution paths. Equipped with this strategy and a powerful codification scheme, the path-finder (i) learns quickly, (ii) deals with continuous-valued inputs and outputs, (iii) exhibits good noise-tolerance and generalization capabilities, (iv) copes with dynamic environments, and (v) solves an instance of the path finding problem with strong performance demands.
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    URL: http://dx.doi.org/10.1007/BF00992702
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    A Reinforcement Connectionist Approach to Robot Path Finding in Non-Maze-Like Environments (1992)
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    Machine learning 8 (1992), S. 363-395 
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    ISSN: 0885-6125
    Keywords: Connectionism ; reinforcement learning ; robot path finding ; stability ; reactive systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper presents a reinforcement connectionist system which finds and learns the suitable situation-action rules so as to generate feasible paths for a point robot in a 2D environment with circular obstacles. The basic reinforcement algorithm is extended with a strategy for discovering stable solution paths. Equipped with this strategy and a powerful codification scheme, the path-finder (i) learns quickly, (ii) deals with continuous-valued inputs and outputs, (iii) exhibits good noise-tolerance and generalization capabilities, (iv) copes with dynamic environments, and (v) solves an instance of the path finding problem with strong performance demands.
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    URL: http://dx.doi.org/10.1023/A:1022684924132
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    The origin of life — A task in molecular engineering (1992)
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    Molecular engineering 1 (1992), S. 377-399 
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    ISSN: 1572-8951
    Keywords: Origin of life ; molecular engineering ; biology ; evolution ; genetic code ; translation machine ; self instruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In attempting to understand how life originated, we search for a detailed sequence of experimentally testable physico-chemical steps in an appropriately structured system. This goal is approached in two stages. First we search for the organizational structure of processes leading to systems with the basic features of living organisms. This is an engineering problem: finding a certain construct by taking care of logical requirements and restrictions from physics. Then we face this construct with the chemical and geophysical reality, and this leads to the view that systems with the essential features of early living organisms evolve following a distinct pathway. Energy supply and the presence of a particular structure in space and time are necessary to induce and drive the processes triggered by stochastic events; but if these particular conditions are given, the broad line of the evolutionary processes is determined by logical requirements and by chemical and geophysical constrains and invariants. The genetic machinery considered to evolve in this manner agrees, in its organizational structure and in many details, with the actual genetic machinery of biosystems. A surprising simplicity and transparency is observed in the logic of the basic processes involved in the origin of life. In the present view, the processes leading to the origin of life begin in a very particular, highly structured, small region where the relevant chemistry can be quite different from overall prebiotic chemistry. Energy-rich compounds are present in ample amounts and a succession of physico-chemical processes, which are per se thermodynamically allowed, takes place. This is in contrast to popular views that the origin of life is connected with fundamental thermodynamic questions related to the problem of getting order out of chaos.
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    Nucleotide sequence ofatpB,rbcL,trnR,dedB andpsaI chloroplast genes from a fernAngiopteris lygodiifolia: a possible emergence of Spermatophyta lineage before the separation of Bryophyta and Pteridophyta (1992)
    Springer
    Plant molecular biology 18 (1992), S. 79-82 
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    ISSN: 1573-5028
    Keywords: Angiopteris lygodiifolia ; atpB ; chloroplast genome ; evolution ; rbcL ; trnR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To elucidate the evolutionary relationship between the Spermatophyta, Pteridophyta and Bryophyta, we cloned a fragment of chloroplast DNA from the fernAngiopteris lygodiifolia (Pteridophyta) and determined its nucleotide sequence. The fragment contained theatpB,rbcL,trnR-CCG,dedB andpsaI genes. Comparisons of the deduced amino acid and nucleotide sequences of these genes from the three plant groups indicate thatAngiopteris sequences are more closely related to those of Bryophyta species (85% identity on average) than to those of seed plants (76% identity on average), supporting a hypothesis that the Bryophyta and Pteridophyta diverged more recently from one another than their common progenitor diverged from that of the Spermatophyta.
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    The activation process of Arabidopsis thaliana A1 gene encoding the translation elongation factor EF-1α is conserved among angiosperms (1992)
    Springer
    Plant molecular biology 18 (1992), S. 1083-1089 
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    ISSN: 1573-5028
    Keywords: translation elongation factor genes ; promoter analysis ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Arabidopsis thaliana, the activation process of the A1 EF-1α gene depends on several elements. Using the GUS reporter gene, transient expression experiments have shown that mutations of upstream cis-acting elements of the A1 promoter, or the deletion of an intron located within the 5′ non-coding region, similarly affect expression in dicot or monocot protoplasts. The results reported here strongly suggest that this 5′ intron is properly spliced in Zea mays. We show that two trans-acting factors, specifically interacting with an upstream activating sequence (the TEF 1 box), are present in nuclear extracts prepared from A. thaliana, Brassica rapa, Nicotiana tabacum and Z. mays. In addition, a DNA sequence homologous to the TEF 1 box, found at approximately the same location within a Lycopersicon esculentum EF-1α promoter, interacts with the same trans-acting factors. Homologies found between the A. thaliana and L. esculentum TEF 1 box sequences have allowed us to define mutations of this upstream element which affect the interaction with the corresponding trans-acting factors. These results support the notion that the activation processes of A. thaliana EF-1α genes have been conserved among angiosperms and provide interesting data on the functional structure of the TEF 1 box.
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    A 16 kb small single-copy region separates the plastid DNA inverted repeat of the unicellular red alga Cyanidium caldarium: physical mapping of the IR-flanking regions and nucleotide sequences of the psbD-psbC, rps16, 5S rRNA and rpl21 genes (1992)
    Springer
    Plant molecular biology 19 (1992), S. 1001-1010 
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    ISSN: 1573-5028
    Keywords: Cyanidium caldarium Geitler ; evolution ; Galdieria sulphuraria ; inverted repeat ; plastid DNA ; psbD-psbC operon ; red algae ; 5S rRNA ; rpl21 ; rps16
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The four inverted repeat (IR) flanking regions of the Cyanidium caldarium plastid DNA were cloned. Southern blotting, transcript and sequence analyses of the border regions revealed the psbD-psbC operon and the rps16 gene within the large single-copy region upstream of the 16S rDNA gene and the rpl21 gene downstream of the 5S rDNA within the 16 kb small single-copy region. The size of the IR is ca. 5 kb. The nucleotide sequences of the psbD-psbC, rps16, rpl21 and 5S rRNA genes with the corresponding alignments and physical maps of the regions are presented. Northern analysis revealed a less complex psbD-psbC transcription pattern than has been found in higher plants. Comparisons to other red algal data point to structural diversity within red algal plastid DNA.
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    Comparison of regions coding for tRNAHis genes of mitochondrial and chloroplast DNA in sunflower: a proposal concerning the classification of ‘CP-like’ tRNA genes (1992)
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    Plant molecular biology 20 (1992), S. 1-4 
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    ISSN: 1573-5028
    Keywords: higher plants ; sunflower ; chloroplast genome ; mitochondrial genome ; tRNAHis genes ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00029143
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    An equivalent to bacterialompR genes is encoded on the plastid genome of red algae (1992)
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    Plant molecular biology 18 (1992), S. 777-780 
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    ISSN: 1573-5028
    Keywords: Cyanidium caldarium ; evolution ; Galdieria sulphuraria ; rRNA operon
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    Topics: Biology
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    URL: http://dx.doi.org/10.1007/BF00020019
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    The structure of the SF6 molecule and the SF 6 − anion excited states (1992)
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    Russian chemical bulletin 41 (1992), S. 504-510 
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    ISSN: 1573-9171
    Keywords: electronic structure ; geometry optimization ; electron affinity ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The electronic and geometric structures of the ground state and a number of excited states of the SF6 molecule and the SF 6 − anion have been calculated by the discrete-variation method of the local density-functionals. The anion was found to possess a number of states stable toward the outer electron detachment, and at least one excited state stable toward dissociation. The adiabatic electron affinity (EA) was determined as 3.46 eV at the highest level of theory. This result is correlated to the high EAs of the isovalent compound SeF6 and TeF6; however, it does not agree with the presently accepted experimental estimate of 1.0 ± 0.2 eV for the SF6EA value. The basic anion configuration is octahedral with a S-F bond length of 1.717 Å. The calculated limit for the highest dissociation channel of the ground state SF 6 − → SF 5 − + F is ≈ 1.5 eV lower than the minimum of the total energy of the neutral molecule; this is in good agreement with experimental estimates.
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    Domatia as most important adaptations in the evolution of myrmecophytes in the paleotropical tree genusMacaranga (Euphorbiaceae) (1992)
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    Plant systematics and evolution 180 (1992), S. 53-64 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Euphorbiaceae ; Macaranga ; Ant-plant interactions ; domatia ; evolution ; myrmecophytism ; Flora of Malaysia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The paleotropical tree genusMacaranga (Euphorbiaceae) comprises all stages of interaction with ants, from facultative associations to obligate myrmecophytes. In SE.-Asia food availability does not seem to be the limiting factor for the development of a close relationship since all species provide food for ants in form of extrafloral nectar and/or food bodies. Only myrmecophyticMacaranga species offer nesting space for ants (domatia) inside internodes which become hollow due to degeneration of the pith. Non-myrmecophytic species have a solid stem with a compact and wet pith and many resin ducts. The stem interior of some transitional species remains solid, but the soft pith can be excavated. The role of different ant-attracting attributes for the development of obligate ant-plant interactions is discussed. In the genusMacaranga, the provision of nesting space seems to be the most important factor for the evolution of obligate myrmecophytism.
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    Phylogenetic evidence for the herbaceous origin of angiosperms (1992)
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    Plant systematics and evolution 180 (1992), S. 137-156 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; evolution ; origin ; ancestral angiosperm ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ancestral angiosperm is commonly interpreted as an arborescent to shrubby magnolialean with large, multiparted, complex flowers. We examined this hypothesis using a phylogenetic analysis of new and reevaluated characters polarizabled with outgroup comparison. Our cladistic analysis of basal angiosperms placed the nonmagnolialeanChloranthaceae andPiperaceae at the bottom of the tree. We further inferred the probable ancestral states of characters not polarizable with outgroup comparison by examining their distribution among taxa at the base of our cladogram. The sum of ancestral character states suggests that the protoangiosperm was a diminutive, rhizomatous to scrambling perennial herb, with small, simple flowers.
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    Isozyme variation and alleged progenitor-derivative relationships in theMedicago murex complex (Fabaceae) (1992)
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    Plant systematics and evolution 181 (1992), S. 33-43 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Fabaceae ; Medicago murex ; M. lesinsii ; Systematics ; evolution ; isozymes ; chromosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromosomal studies ofMedicago lesinsii (n = 8) and its close relativeM. murex (n = 7) have led to the competing hypotheses that the latter is derived directly from the former, or that both originated from a common ancestor. In contrast to the relatively variableM. murex, M. lesinsii proved to be almost uniform isozymically, except that most populations of Greece differed by one allele from plants of the remainder of the range. This Greek variant ofM. lesinsii was indistinguishable from one of the isozyme variants ofM. murex. The greater level of allozyme variation inM. murex was consistent with its greater ecological amplitude and competitive ability. Also, this suggests thatM. murex is unlikely to have originated directly from the less variableM. lesinsii. The data suggest that either both species originated from a common ancestor, or that the n = 8 species evolved from the n = 7 species, a mode of chromosome evolution not previously hypothesized for the genus.
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    Phenetic, biogeographical, and evolutionary study ofOrnithogalum subg.Heliocharmos (Hyacinthaceae) in the western Mediterranean basin (1992)
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    Plant systematics and evolution 181 (1992), S. 179-202 
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    ISSN: 1615-6110
    Keywords: Hyacinthaceae ; Ornithogalum ; Heliocharmos ; O. algeriense ; O. kochii ; O. orthophyllum ; O. umbellatum ; Numerical taxonomy ; phenetics ; systematics ; biogeography ; evolution ; Flora of North Africa ; Mediterranean ; Morocco ; Spain ; France
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A macromorphological study is made on taxa of the genusOrnithogalum subg.Heliocharmos in North Africa, Spain, and France. The results obtained are consistent with data from cytogenetics, reproductive biology and strategies of reproduction. They allow the retention of two species:O. algeriense andO. umbellatum. A biogeographical and phylogenetic interpretation of the subgenus is proposed for the western Mediterranean. Theoretical views on phenetics are discussed.
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    The 5S DNA units ofAcacia species (Mimosaceae) (1992)
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    Plant systematics and evolution 183 (1992), S. 235-247 
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    ISSN: 1615-6110
    Keywords: Angiosperms ; Mimosaceae ; Acacia ; 5S DNA ; evolution ; phylogeny ; chromosomal lineages
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The DNA sequence structure of 5S DNA units inAcacia species, including representatives from the three subgenera ofAcacia, have been determined. The data was interpreted to suggest that at least three lineages of 5S DNA sequences exist inAcacia and the proposal was made that the lineages be named5S Dna-1, 5S Dna-2, and5S Dna-3. The5S Dna-1 lineage was represented by units fromA. boliviana andA. bidwilli, the5S Dna-2 lineage by units fromA. melanoxylon, A. pycnantha, A. ulicifolia, A. boliviana, A. bidwillii, andA. albida, and the5S Dna-3 lineage by units fromA. bidwillii, A. boliviana, andA. senegal. Based on this interpretation of the sequence data, the Australian species of subg.Phyllodineae grouped together as a cluster, quite separate from the subgeneraAculeiferum andAcacia. As expected from the analyses of morphological characters, the 5S DNA units fromAcacia albida (syn.Faidherbia albida) were quite separate from the otherAcacia spp.
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    Relationships betweenOryza species (Poaceae) based on 5S DNA sequences (1992)
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    Plant systematics and evolution 183 (1992), S. 249-264 
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    ISSN: 1615-6110
    Keywords: Poaceae ; Oryza ; 5S DNA ; phylogeny ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Relationships between 9Oryza species, covering 6 different genomes, have been studied using hybridization and nucleotide sequence information from the5S Dna locus. Four to five units of the major size class of 5S DNA in each species, 55 units in all, were cloned and sequenced. Both hybridization and sequence data confirmed the basic differences between the A and B, C, D genome species suggested by morphological and cytological data. The 5S DNA units of the A genome species were very similar, as were the ones from the B, C, and D genome-containing species. The 5S DNA ofO. australiensis (E genome) grouped with the B, C, D cluster, while the units ofO. brachyantha (F genome) were quite different and grouped away from all other species. 5S DNA units fromO. minuta, O. latifolia, O. australiensis, andO. brachyantha hybridized strongly, and preferentially, to the genomic DNA from which the units were isolated and hence could be useful as species/genome specific probes. The 5S DNA units fromO. sativa, O. nivara, andO. rufipogon provided A genome-specific probes as they hybridized preferentially to A genome DNA. The units fromO. punctata andO. officinalis displayed weaker preferential hybridization toO. punctata DNA, possibly reflecting their shared genome (C genome).
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    Mental content and evolutionary explanation (1992)
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    Biology and philosophy 7 (1992), S. 1-12 
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    ISSN: 1572-8404
    Keywords: Cognitive ethology ; mental content ; mental representations ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Cognitive ethology is the comparative study of animal cognition from an evolutionary perspective. As a sub-discipline of biology it shares interest in questions concerning the immediate causes and development of behavior. As a part of ethology it is also concerned with questions about the function and evolution of behavior. I examine some recent work in cognitive ethology, and I argue that the notions of mental content and representation are important to enable researchers to answer questions and state generalizations about the function and volution of behavior.
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    What is hierarchical selection? (1992)
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    Biology and philosophy 7 (1992), S. 27-33 
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    ISSN: 1572-8404
    Keywords: Additivity ; ANOVA ; evolution ; hierarchical selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract It has been proposed that natural selection occurs on a hierarchy of levels, of which the organismic level is neither the top nor the bottom. This hypothesis leads to the following practical problem: in general, how does one tell if a given phenomenon is a result of selection on level X or level Y. How does one tell what the units of selection actually are? It is convenient to assume that a unit of selection may be defined as a type of entity for which there exists, among all entities on the same “level” as that entity, an additive component of variance for some specific component F of fitness which does not appear as an additive component of variance in any decomposition of this F among entities at any lower level. But such a definition implicitly assumes that if f(x, y) depends nonadditively on its arguments, there must be interaction between the quantities which x and y represent. This assumption is incorrect. And one cannot avoid this error by speaking of “transformability to additivity” instead of merely “additivity”. A general mathematical formulation of the concepts of interaction and non-interaction is proposed, followed by a correspondingly modified approach to the definition of a unit of selection. The practical difficulty of verifying the presence of hierarchical selection is discussed.
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    An ecological approach to biosystem thermodynamics (1992)
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    Biology and philosophy 7 (1992), S. 35-60 
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    ISSN: 1572-8404
    Keywords: Action principles ; ecosystem structure ; evolution ; information ; natural selection ; non-equilibrium thermodynamics ; teleology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract The general attributes of ecosystems are examined and a naturally occurring “reference ecosystem” is established, comparable with the “isolated” system of classical thermodynamics. Such an autonomous system with a stable, periodic input of energy is shown to assume certain structural characteristics that have an identifiable thermodynamic basis. Individual species tend to assume a state of “least dissipation”; this is most clearly evident in the dominant species (the species with the best integration of energy acquisition and conservation). It is concluded that ecosystem structure results from the antagonistic interaction of two nearly equal forces. These forces have their origin in the Principle of Most Action (“least dissipation” or “least entropy production”) and the universal Principle of Least Action. “Most action” is contingent on the equipartitioning of the energy available, through uniform interaction of similar individuals. The trend to “Least action” is contingent on increased dissipation attained through increasing diversity and increasing complexity. These principles exhibit a basic asymmetry. Given the operation of these opposing principles over evolutionary time, it is argued that ecosystems originated in the vicinity of thermodynamic equilibrium through the resonant amplification of reversible fluctuations. On account of the basic asymmetry the system was able to evolve away from thermodynamic equilibrium provided that it remained within the vicinity of “ergodynamic equilibrium” (equilibrium maintained by internal work, where the opposing forces are equal and opposite). At the highest level of generalization there appear to be three principles operating: i) maximum association of free-energy and materials; ii) energy conservation (deceleration of the energy flow) through symmetric interaction and increased homogeneity; and iii) the principle of least action which induces acceleration of the energy flow through asymmetrical interaction. The opposition and asymmetry of the two forces give rise to natural selection and evolution.
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    On the relationship between evolutionary and psychological definitions of altruism and selfishness (1992)
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    Biology and philosophy 7 (1992), S. 61-68 
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    ISSN: 1572-8404
    Keywords: Altruism ; evolution ; group selection ; selfishness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract I examine the relationship between evolutionary definitions of altruism that are based on fitness effects and psychological definitions that are based on the motives of the actor. I show that evolutionary altruism can be motivated by proximate mechanisms that are psychologically either altruistic or selfish. I also show that evolutionary definitions do rely upon motives as a metaphor in which the outcome of natural selection is compared to the decisions of a psychologically selfish (or altruistic) individual. Ignoring the precise nature of both psychological and evolutionary definitions has obscured many important issues, including the biological roots of psychological altruism.
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    Evolution, altruism, and the prisoner's dilemma (1992)
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    Biology and philosophy 7 (1992), S. 161-175 
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    ISSN: 1572-8404
    Keywords: Altruism ; evolution ; Prisoner's Dilemma ; sociobiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract I first argue against Peter Singer's exciting thesis that the Prisoner's Dilemma explains why there could be an evolutionary advantage in making reciprocal exchanges that are ultimately motivated by genuine altruism over making such exchanges on the basis of enlightened long-term self-interest. I then show that an alternative to Singer's thesis — one that is also meant to corroborate the view that natural selection favors genuine altruism, recently defended by Gregory Kavka, fails as well. Finally, I show that even granting Singer's and Kavka's claim about the selective advantage of altruism proper, it is doubtful whether that type of claim can be used in a particular sort of sociobiological argument against psychological egoism.
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    The evolution of altruism: Correlation, cost, and benefit (1992)
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    Biology and philosophy 7 (1992), S. 177-187 
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    ISSN: 1572-8404
    Keywords: Altruism ; evolution ; game theory ; group selection ; kin selection ; prisoner's dilemma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract A simple and general criterion is derived for the evolution of altruism when individuals interact in pairs. It is argued that the treatment of this problem in kin selection theory and in game theory are special cases of this general criterion.
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    Phylogenetic definitions and taxonomic philosophy (1992)
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    Biology and philosophy 7 (1992), S. 295-313 
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    ISSN: 1572-8404
    Keywords: Clade ; class ; composite whole ; definition ; defining property ; essentialism ; evolution ; individual ; intension ; name ; ostensive definition ; phylogeny ; population ; set ; species ; taxon ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract An examination of the post-Darwinian history of biological taxonomy reveals an implicit assumption that the definitions of taxon names consist of lists of organismal traits. That assumption represents a failure to grant the concept of evolution a central role in taxonomy, and it causes conflicts between traditional methods of defining taxon names and evolutionary concepts of taxa. Phylogenetic definitions of taxon names (de Queiroz and Gauthier 1990) grant the concept of common ancestry a central role in the definitions of taxon names and thus constitute an important step in the development of phylogenetic taxonomy. By treating phylogenetic relationships rather than organismal traits as necessary and sufficient properties, phylogenetic definitions remove conflicts between the definitions of taxon names and evolutionary concepts of taxa. The general method of definition represented by phylogenetic definitions of clade names can be applied to the names of other kinds of composite wholes, including populations and biological species. That the names of individuals (composite wholes) can be defined in terms of necessary and sufficient properties provides the foundation for a synthesis of seemingly incompatible positions held by contemporary individualists and essentialists concerning the nature of taxa and the definitions of taxon names.
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    The vibration and stability analysis of moderate thick plates by the method of lines (1992)
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    Applied mathematics and mechanics 13 (1992), S. 523-531 
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    ISSN: 1573-2754
    Keywords: moderate thick plate ; vibration ; stability ; method of lines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract The method of lines based on Hu Hai-chang's theory for the vibration and stability of moderate thick plates is developed. The standard nonlinear ordinary differential equation (ODE) system for natural frequencies and critical load is given by use of ODE techniques, and then any indicated eigenvalue could be obtained directly from ODE solver by employing the so-called initial eigenfunction technique instead of the mode orthogonality condition. Numerical examples show that the present method is very effective and reliable.
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    Adaptive foraging by predators as a cause of predator-prey cycles (1992)
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    Evolutionary ecology 6 (1992), S. 56-72 
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    ISSN: 1573-8477
    Keywords: dynamics of adaptation ; optimal foraging ; predator-prey cycles ; stability ; type-2 functional response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary When foraging has costs, it is generally adaptive for foragers to adjust their foraging effort in response to changes in the population density of their food. If effort decreases in response to increased food density, this can result in a ‘type-2’ functional response; intake rate increases in a negatively accelerated manner as prey density increases. Unlike other mechanisms for type-2 responses, adaptive foraging usually involves a timelag, because foraging behaviours do not often change instantaneously with changes in food density or risks. This paper investigates predator-prey models in which there are explicit dynamics for the rate of adaptive change. Models appropriate to both behavioural and evolutionary change are considered. Both types of change can produce cycles under similar circumstances, but under some evolutionary models there is not sufficient genetic variability for evolutionary change to produce cycles. If there is sufficient variability, the remaining conditions required for cycles are surprisingly insensitive to the nature of the adaptive process. A predator population that approaches the optimum foraging strategy very slowly usually produces cycles under similar conditions as does a very rapidly adapting population.
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    URL: http://dx.doi.org/10.1007/BF02285334
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    Parental care and the allocation of resources across generations (1992)
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    Evolutionary ecology 6 (1992), S. 187-197 
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    ISSN: 1573-8477
    Keywords: parental care ; resource allocation ; ESS ; inclusive fitness ; menopause ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary To understand the evolution of parental care behaviour, the cost of care must be evaluated in terms of lost reproductive potential. Using population genetics theory, a quantitative model of parental care is presented here to evaluate the allocation of resources between production and care of offspring, and care of grandoffspring. The results show that the evolutionarily stable investment ratio of resources to offspring versus grandoffspring is equal to 2∶1. The expected investment in grandoffspring will decrease when there is a lower probability of survival of the parents to a late stage of the life cycle. These results are discussed in the context of general life history theory, inclusive fitness models, animal behaviour field studies, and the evolution of human menopause.
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    Phylogenetic analysis of pines using ribosomal DNA restriction fragment length polymorphisms (1992)
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    Plant systematics and evolution 179 (1992), S. 141-153 
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    ISSN: 1615-6110
    Keywords: Gymnosperms ; Conifers ; Pinaceae ; Pinus ; rDNA ; restriction fragments ; molecular systematics ; evolution ; phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic relationships among 30 species of the genusPinus were studied using restriction site polymorphism in the large subunit of nuclear rDNA. Of the 58 restriction sites scored, 48 were phylogenetically informative, and the 30 species reduced to ten taxa when species with identical restriction site patterns were combined. These ten taxa corresponded to the currently recognized subsections of the genus, with the sole exception ofP. leiophylla, which was identical in its pattern of restriction sites to all three species included from subsect.Oocarpae despite its being in a different section of subg.Pinus (Pinea instead ofPinus). A measure of the proportion of phylogenetic information contained within the data set (Homoplasy Excess Ratio, or HER) revealed that the character states were significantly non-randomly distributed among the ten taxa (HER = 0.71, p 〈 0.01). Branchand-bound searches using either Wagner or Dollo parsimony as the optimization criterion were carried out using PAUP in order to estimate phylogenetic relationships among the ten taxa. Three taxa (Picea pungens, Tsuga canadensis, andLarix decidua) were used independently as outgroups for purposes of rooting the trees. Despite the extreme differences in the assumptions underlying the Wagner and Dollo parsimony, the two gave surprisingly similar estimates of phylogeny, with both analyses supporting the monophyly of the two major subgeneraPinus andStrobus and differing in topology only in the placement of subsect.Ponderosae within subg.Pinus. The likelihood for the Wagner tree was only slightly higher than that computed for the Dollo tree.
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    The importance of Endosperm Balance Number in potato breeding and the evolution of tuber-bearing Solanum species (1992)
    Springer
    Euphytica 60 (1992), S. 105-113 
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    ISSN: 1573-5060
    Keywords: bridging crosses ; chromosome addition lines ; Endosperm Balance Number ; evolution ; 2n gametes ; imprinting ; interspecific crosses ; ploidy manipulations ; tuber-bearing Solanum species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Endosperm failure is considered the primary reason for the lack of success in intra-and interspecific crosses. The Endosperm Balance Number (EBN) hypothesis is a unifying concept for predicting endosperm function in intraspecific, interploidy, and interspecific crosses. In the EBN system, every species has an ‘effective ploidy’ (EBN), which must be in a 2:1 maternal to paternal ratio in the endosperm for crosses to succeed. The knowledge of EBN is very useful in the transfer of genes from exotic germplasm, and in the development of new breeding schemes in potato. The paper describes the strategies for introducing 2x(1EBN), 2x(2EBN), 4x(2EBN) and 6x(4EBN) germplasm into the cultivated 4x(4EBN) potato gene pool. A new methodology for producing 4x(4EBN) and 2x(2EBN) chromosome addition lines is also discussed. EBN has evolutionary importance in the origin of tuber-bearing Solanums. The role of the EBN in the origin of diploid and polyploid potato species, and as a barrier for hybridization and speciation of sympatric species within the same ploidy level is demonstrated. The origin of 3x and 5x cultivated tuber-bearing Solanums may also be explained using the EBN concept. EBN has been reported to exist in other plant species: alfalfa, beans, blueberries, rice, soybeans, squashes, tomato, forage legumes, grasses, ornamentals and Datura stramonium. This indicates that EBN may have broad application and could be useful for germplasm transfer and breeding in other crop species.
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    Adaptation of barley (Hordeum vulgare L.) to harsh Mediterranean environments (1992)
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    Euphytica 62 (1992), S. 29-38 
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    ISSN: 1573-5060
    Keywords: adaptation ; barley ; drought ; heading date ; plant ideotype ; principal component analysis ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Barley adapted to the combined stresses of low winter temperatures and terminal drought requires a medium carly heading date, little affected by environmental fluctuations. Two plant ideotypes that are adapted to terminal drought in Mediterranean environments can be distinguished. The first combines early heading with good early vigour, erect winter growth habit, light plant colour, and ability to recover from cold damage. The second combines medium early heading, prostrate winter growth habit, dark winter plant colour which changes to pale green in spring, and cold tolerance. This study was conducted to determine the relationship between consistency in heading date and plant ideotype, and to identify the usefulness of earliness and plant ideotype as criteria for indirect selection for grain yield under drought. Thirty-six two-rowed entries of barley (Hordeum vulgare L.) were sown at 15 environments in northern Syria. Average grain yields ranged from 7 to 331 g/m2; the range in average heading date was 20 days. Consistency in date of heading was related to the second ideotype through vernalization requirement. Early heading was positively correlated with grain yield in most of the environments, but especially in low-yielding environments. After eliminating the effect of heading date, the second plant ideotype was advantageous only under harsh conditions. In early generations, selection under favourable conditions for earliness, prostrate winter growth habit, dark winter plant colour, and cold tolerance is a useful alternative for yield testing, to identify material well adapted to environments experiencing low winter temperatures and terminal drought stress. Selection for the first plant ideotype is proposed for Mediterranean environments with mild winters.
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    Light, iron, Sam Granick and the origin of life (1992)
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    Photosynthesis research 33 (1992), S. 163-170 
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    ISSN: 1573-5079
    Keywords: biosynthetic pathway ; evolution ; free energy ; photochemistry ; photosynthesis ; porphyrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Living matter is an organized system which requires a continual flux of energy for its survival. As a working assumption, the flux of energy required for the origin of a self-duplicating cell is taken as the power required for the maintenance of a modern cell: 10 mW per g of carbon or some 105 times the output per gram of the sun. Solar photochemistry supplies the energy for the continuing evolution of life and, by continuity, for its origin. The iron oxide-sulfide photosynthetic unit proposed by S. Granick 35 years ago was meant to supply this energy. The evolution of complex organic photosensitizers is rationalized by the Granick hypothesis that biosynthetic pathways recapitulate their evolution. These concepts are discussed in the context of the evolution of photosynthetic systems and the known properties of these pigments.
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    Protein sequences and redox titrations indicate that the electron acceptors in reaction centers from heliobacteria are similar to Photosystem I (1992)
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    Photosynthesis research 32 (1992), S. 11-22 
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    ISSN: 1573-5079
    Keywords: iron-sulfur centers ; evolution ; green sulfur bacteria ; bacteriochlorophyll g
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic reaction centers isolated from Heliobacillus mobilis exhibit a single major protein on SDS-PAGE of 47 000 Mr. Attempts to sequence the reaction center polypeptide indicated that the N-terminus is blocked. After enzymatic and chemical cleavage, four peptide fragments were sequenced from the Heliobacillus mobilis apoprotein. Only one of these sequences showed significant specific similarity to any of the protein and deduced protein sequences in the GenBank data base. This fragment is identical with 56% of the residues, including both cysteines, found in the highly conserved region that is proposed to bind iron-sulfur center FX in the Photosystem I reaction center peptide that is the psaB gene product. The similarity to the psaA gene product in this region is 48%. Redox titrations of laser-flash-induced photobleaching with millisecond decay kinetics on isolated reaction centers from Heliobacterium gestii indicate a midpoint potential of −414 mV with n=2 titration behavior. In membranes, the behavior is intermediate between n=1 and n=2, and the apparent midpoint potential is −444 mV. This is compared to the behavior in Photosystem I, where the intermediate electron acceptor A1, thought to be a phylloquinone molecule, has been proposed to undergo a double reduction at low redox potentials in the presence of viologen redox mediators. These results strongly suggest that the acceptor side electron transfer system in reaction centers from heliobacteria is indeed analogous to that found in Photosystem I. The sequence similarities indicate that the divergence of the heliobacteria from the Photosystem I line occurred before the gene duplication and subsequent divergence that lead to the heterodimeric protein core of the Photosystem I reaction center.
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    Effects of pre-storage conditions on storage of in vitro cultures of Nephrolepis exaltata (L.) Schott and Cordyline fruticosa (L.) A. Chev. (1992)
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    Plant cell, tissue and organ culture 28 (1992), S. 167-174 
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    ISSN: 1573-5044
    Keywords: dark ; in vitro storage ; light ; stability ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro cultures of Nephrolepis exaltata and Cordyline fruticosa were stored at 5°, 9° or 13°C, at a low irradiance (3–5 μmol m−2 s−1) or in darkness. Prior to storage the cultures were subjected to 18°, 21°, 24° or 27°C and 15, 30 or 45 μmol m−2 s−1 in a factorial combination. The optimal storage conditions for Nephrolepis were 9°C in complete darkness. These cultures were still transferable to a peat/perlite mixture at the end of the experimental period of 36 months. The optimal storage conditions for Cordyline were 13°C and a low light level (±3–5 μmol m-2 s-1). When the pre-storage conditions were normal growth room conditions (24°C and 30 μmol m-2 s-1), in vitro cultures could be stored for 18 months. With the most favourable pre-storage treatment (18°C and 15 μmol m-2 s-1) some cultures still had green shoots after 36 months of storage, but did not survive transfer to peat/perlite. Pre-conditioning before storage was most favourable for Nephrolepis, and not that important, but still favourable, for Cordyline. There was an interaction between pre-storage temperature and pre-storage irradiance. For both species a high irradiance level was less favourable than a low irradiance level when combined with high growth room temperatures.
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    Predictability of streamflow and particulate organic matter concentration as indicators of stability in prairie streams (1992)
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    Hydrobiologia 242 (1992), S. 7-18 
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    ISSN: 1573-5117
    Keywords: POM ; prairie streams ; predictability ; stability ; stream flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Predictability of stream discharge and particulate organic matter (POM) in the water column was estimated, using Colwell's indices of constancy and contingency, for 6 Texas prairie streams (1 each of 2nd, 3rd, and 4th order with intermittent or perennial discharge). Stream discharge in these 6 prairie streams varied between 0 and 36000 1 s−1, depending on the stream and season. Predictability (P) of discharge in these streams ranged from 0.45 to 0.62, within the range of values expected for North American streams. Predictability of stream discharge was not significantly different between streams. Particulate organic matter concentrations in these prairie streams are relatively low, ranging from 0.25 to 4.00 mg AFDM 1−1. Predictability of POM concentration in these streams was high, ranging from 0.75 to 0.85, and was largely the result of constancy of POM concentrations. Within the different POM size classes, Fine POM (FPOM) had the highest predictability (P = 0.89−0.96). In spite of relatively unpredictable stream discharge, POM remained fairly constant providing a measure of habitat predictability and stability.
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    Quantitative nuclear DNA differences associated with genome evolution in Guizotia (Compositae) (1992)
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    Genetica 85 (1992), S. 241-247 
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    ISSN: 1573-6857
    Keywords: Compositae ; DNA amount ; evolution ; Guizotia ; karyotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The present communication deals with 2C nuclear genome size variation in a fairly small genus Guizotia. Twenty-four accessions belonging to six species, out of seven known, were analysed in order to elucidate the extent of DNA variation both at an intra—as well as interspecific level. At the intraspecific level none of the species exhibited significant differences in their genome size. Between the species, the 2C DNA amounts ranged from 3.61 pg in G. reptans to 11.37 pg in G. zavattarii; over three-fold DNA variation is evident. Apparently these interspecific DNA differences have been achieved independent of the numerical chromosomal change(s), as all the Guizotias share a common chromosome number 2n=2x=30. The cultivated oilseed crop, G. abyssinica (7.57 pg), has accommodated nearly 78% extra DNA in its chromosome complement during the evolutionary time scale of its origin and domestication from the wild progenitor G. schimperi (4.25 pg). The extent of genomic DNA difference(s) between the species has been discussed in the light of their interrelationships and diversity.
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    Ty1-copia group retrotransposons and the evolution of retroelements in the eukaryotes (1992)
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    Genetica 86 (1992), S. 203-214 
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    ISSN: 1573-6857
    Keywords: Copia ; Ty element ; evolution ; retrotransposon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ty1-copia group retrotransposons are among the best studied transposable elements in the eukaryotes. This review discusses the extent of these transposons in the eukaryote kingdoms and compares models for the evolution of these genetic elements in the light of recent phylogenetic data. These data show that the Ty1-copia group is widespread among invertebrate eukaryotes, especially in the higher plant kingdom, where these genetic elements are unusually common and heterogeneous in their sequence. The phylogenetic data also suggest that the present day spectrum of Ty1-copia group retrotransposons has been influenced both by divergence during vertical transmission down evolving lineages and by horizontal transmission between distantly related species. Lastly, the factors affecting Ty1-copia group retrotransposon copy number and sequence heterogeneity in eukaryotic genomes and the effects of transpositional quiescence and defective retrotransposons upon evolution of Ty1-copia group retrotransposons are discussed.
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    Evolution of structure and function of V-ATPases (1992)
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    Journal of bioenergetics and biomembranes 24 (1992), S. 415-424 
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    ISSN: 1573-6881
    Keywords: ATPases ; evolution ; eukaryotes ; endomembranes ; archaebacteria ; progenote ; bioenergetics ; flagella assembly ; endosymbiont theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Proton pumping ATPases/ATPsynthases are found in all groups of present-day organisms. The structure of V- and F-type ATPases/ATP synthases is very conserved throughout evolution. Sequence analysis shows that the V- and F-type ATPases evolved from the same enzyme already present in the last common ancestor of all known extant life forms. The catalytic and noncatalytic subunits found in the dissociable head groups of the V/F-type ATPases are paralogous subunits, i.e., these two types of subunits evolved from a common ancestral gene. The gene duplication giving rise to these two genes (i.e., encoding the catalytic and noncatalytic subunits) predates the time of the last common ancestor. Mapping of gene duplication events that occurred in the evolution of the proteolipid, the noncatalytic and the catalytic subunits, onto the tree of life leads to a prediction for the likely subunit structure of the encoded ATPases. A correlation between structure and function of V/F-ATPases has been established for present-day organisms. Implications resulting from this correlation for the bioenergetics operative in proto-eukaryotes and in the last common ancestor are presented. The similarities of the V/F-ATPase subunits to an ATPase-like protein that was implicated to play a role in flagellar assembly are evaluated. Different V-ATPase isoforms have been detected in some higher eukaryotes. These data are analyzed with respect to the possible function of the different isoforms (tissue specific, organelle specific) and with respect to the point in their evolution when these gene duplications giving rise to the isoforms had occurred, i.e., how far these isoforms are distributed.
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    Lyapunov's direct method in the estimation of the Hausdorff dimension of attractors (1992)
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    Acta applicandae mathematicae 26 (1992), S. 1-60 
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    ISSN: 1572-9036
    Keywords: 58F13 ; Hausdorff measure ; Hausdorff dimension ; strange attractor ; Lorenz system ; Rössler system ; Lyapunov function ; stability ; chaos ; weakly contracting system ; monostability ; frequency theorem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper surveys results of the authors and others conceming estimates for the Hausdorff dimension of strange attractors, particularly in the case of (generalized) Lorenz systems and Rössler systems. A key idea is the interpretation of Hausdorff measure as an analogue of a Lyapunov function.
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    Chemical reactions as dynamical systems on the interval (1992)
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    Journal of statistical physics 66 (1992), S. 1557-1574 
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    ISSN: 1572-9613
    Keywords: Boltzmann ; chemical kinetics ; stability ; chaos ; entropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We consider the most general chemical reaction of the typen 1 A 1+...+n N A N ⇌m 1 B 1+...+m M B M whereN,M⩾1,n 1,...,n N andm 1,...,m M are positive integers defining the stoichiometry, andA 1,...,A N andB 1,...,B M are the names of chemicals or ions. We assume that ∑ i=1 N ni=∑ j=1 M mj. The time evolution of the concentrations is given by the law of mass action and leads to a dynamical system (with discrete or continuous time) which is governed by a polynomial map of the interval [B, C], where B⩾0 and C⩽1. We define the physically meaningful range for the parameters of the map, and we show that, within such a range, the map has a unique fixed point, which is stable and a global attractor, with the exception of one particular case, where bifurcation is observed.
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    Reconsidering the green revolution: Diversity and stability in cradle areas of crop domestication (1992)
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    Human ecology 20 (1992), S. 145-167 
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    ISSN: 1572-9915
    Keywords: agriculture ; development ; diversity ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Ethnic Sciences
    Notes: Abstract This paper reconsiders two widely held hypotheses about the effects of the green revolution, that it led to biological simplification and instability. The hypothesis of biological simplification (genetic erosion) is tested with evidence from Andean agriculture, where farmers maintain a significant degree of crop diversity even as they adopt modern crop varieties. The hypothesis of increased instability is tested with evidence from Asia where wheat and rice yields show no general pattern of increased instability. Neither of these hypotheses is confirmed. The conventional wisdom about the green revolution should be reconsidered with emphasis on resilience and variation in modernizing farming systems.
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    The Cuban homegarden ‘conuco’: a perspective environment for evolution and in situ conservation of plant genetic resources (1992)
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    Genetic resources and crop evolution 39 (1992), S. 9-22 
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    ISSN: 1573-5109
    Keywords: Cuba ; evolution ; genetic resources ; homegarden ; in situ conservation ; landraces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Cuban homegardens are called ‘conucos’. On the basis of new case studies additional information is provided about these ‘conucos’, their history, composition and importance. They and other gardens of similar type are characterized as suitable environment for in situ conservation and for the continuation of evolutionary processes.
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    Spatial and temporal trends in stream macroinvertebrate communities: the influence of catchment disturbance (1992)
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    Hydrobiologia 241 (1992), S. 173-194 
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    ISSN: 1573-5117
    Keywords: disturbance ; recovery ; fire ; streams ; stability ; macroinvertebrates ; watershed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Macroinvertebrate communities of five headwater streams in catchments disturbed by wildfire were compared with five similar streams with no catchment disturbance. Over the five years of observation, communities in disturbed streams were more similar to one another than they were to reference streams. Communities in disturbed streams exhibited more year-to-year variation than reference streams, although some indication of decreasing variation was evident through time, and species richness was greater in reference streams than disturbed streams. No increasing trend in richness over time was observed in disturbed streams. Stability of the relative abundance structure and persistence of dominant taxa through time may be characteristic of temperate streams over moderate time intervals. Local effects of catchment-wide disturbance have persistent effects that alter these trends.
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    Insect resistance in potatoes: sources, evolutionary relationships, morphological and chemical defenses, and ecogeographical associations (1992)
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    Euphytica 61 (1992), S. 83-111 
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    ISSN: 1573-5060
    Keywords: chemical defense ; Colorado potato beetle ; Empoasca fabae ; Epitrix cucumeris ; evolution ; germplasm ; green peach aphid ; insect resistance ; Leptinotarsa decemlineata ; Macrosiphum euphorbiae ; morphology ; Myzus persicae ; potato aphid ; potato flea beetle ; potato leafhopper ; relationship ; Solanum ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The past 25 years, 1686 potato accessions, representing 100 species in the genus Solanum L., subgenus Potatoe, section Petota, were evaluated for field resistance to one or more of the following insect pests: green peach aphid, Myzus persicae (Sulzer); potato aphid, Macrosiphum euphorbiae (Thomas); Colorado potato beetle, Leptinotarsa decemlineata (Say); potato flea beetle, Epitrix cucumeris (Harris); and potato leafhopper, Empoasca fabae (Harris). Accessions highly resistant to green peach aphid were identified within 36 species, to potato aphid within 24 species, to Colorado potato beetle within 10 species, to potato flea beetle within 25 species, and to potato leafhopper within 39 species. Resistance levels were characteristic within Solanum species. Insect resistance appears to be a primitive trait in wild potatoes. Susceptibility was most common in the primitive and cultivated Tuberosa. Insect resistance was also characteristic of the most advanced species. The glycoalkaloid tomatine was associated with field resistance to Colorado potato beetle and potato leafhopper. Other glycoalkaloids were not associated with field resistance at the species level. Dense hairs were associated with resistance to green peach aphid, potato flea beetle, and potato leafhopper. Glandular trichomes were associated with field resistance to Colorado potato beetle, potato flea beetle, and potato leafhopper. Significant correlations between insect score and altitude of original collection were observed in six of thirteen species. Species from hot and arid areas were associated with resistance to Colorado potato beetle, potato flea beetle, and potato leafhopper. Species from cool or moist areas tended to be resistant to potato aphid.
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    URL: http://dx.doi.org/10.1007/BF00026800
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    Alteration of the structural attributes of a compact clay loam soil by growth of a perennial grass crop (1992)
    Springer
    Plant and soil 139 (1992), S. 195-202 
    Details
    ISSN: 1573-5036
    Keywords: bulk density ; epoxy resin impregnation ; image analysis ; macroporosity ; nitrogen ; stability ; strength ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil aggregate stability, organic matter content, pH, bulk density, strength, and macropore attributes were assessed in order to evaluate the influence of grass root growth in a field sward. The amount of grass grown was varied by varying the quantity of applied nitrogen fertilizer: following one year with a uniform application rate, nitrogen fertilizer was applied over the subsequent three years to a compact soil at zero (N0), moderate (N1) and high (N2) rates. Differences in herbage production were evident in the three years of the contrasting nitrogen treatments. An index of soil aggregate stability increased in response to the increased grass growth promoted by heavier applications of nitrogen, but both bulk density and vane shear strength were unchanged. Binary images of the soil solid and pore space showed that for each treatment the largest volume of macropores occurred close to the surface, particularly in N0 where there was more pore space than in either N1 or N2. Analysis of the pore structure attributes of the binary images revealed further differences between treatments, in particular, at 40–80 mm depth, the soil in treatment N0 had fewer and smaller pores, and greater distance between pores, than the soil in the N1 and N2 treatments. The larger macropore volume in N1 and N2 constituted a major portion of the air-filled porosity when the soil was relatively wet. It was concluded that the root growth in the intensively cropped grassland was conducive to maintenance of a relatively stable and porous soil structure. An attendant increase in soil acidity close to the soil surface was a disadvantage of the larger nitrogen inputs.
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    URL: http://dx.doi.org/10.1007/BF00009310
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    The impact of genotype x soil texture interaction on the efficiency of selection for yield in maize (Zea mays L.) (1992)
    Springer
    Euphytica 61 (1992), S. 61-65 
    Details
    ISSN: 1573-5060
    Keywords: population improvement ; maize ; Zea mays ; honeycumb selection ; adaptability ; stability ; yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary This study was undertaken to investigate the implications of genotype x soil texture interaction on response to selection in maize. Mass honeycomb selection for yield was applied for 11 cycles from the F2 of the single cross maize hybrid F68×NE2 in a field B with silty-clay-loam soil texture. Response to selection compared to the original single cross hybrid was estimated both in absence of competition and under solid stand in the selection field B and in a nearby field A differing in soil texture (clay-loam). A strong crossover type of interaction occurred both under solid stand and in the absence of competition in the two tests the improved population outyielded the hybrid in field B in the two densities, but lagged behing the hybrid in field A. The results suggest that interaction between genotype and soil texture might affect efficiency of selection detrimentally unless provision is taken for parallel selection early in the crop improvement program in fields differing in soil texture.
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    URL: http://dx.doi.org/10.1007/BF00035547
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    Adaptation and yield stability of selected lines of Lathyrus spp. under rainfed conditions in West Asia (1992)
    Springer
    Euphytica 66 (1992), S. 89-97 
    Details
    ISSN: 1573-5060
    Keywords: chickling ; Lathyrus ; G×E interactions ; adaptation ; stability ; heritability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Sixteen promising lines (selections) of Lathyrus spp. (chicklings), comprising 11 L. sativus, four L. ochrus, and one L. cicera, were evaluated under rainfed conditions in Syria. Two locations in each of four years were treated as separate environments, to give eight environments altogether. Genotype x environment (G×E) interactions were analysed using linear regression. There was considerable variation in herbage and seed yields within both lines and environments. Genotype x environment interactions were present for both herbage and seed yields; a little over half was accounted for by the linear regression. The non-linear component was also significant, although it was smaller than that of the linear component. The most stable herbage and seed yields were obtained from L. sativus. Two selections, 347 and 311, origmating from Syria and Turkey respectively, combined both high herbage and seed yields with wide adaptation and stability, and could be considered the most widely adapted lines. Other lines were identified as suitable for favourable and unfavourable environments; in particular, all four lines of L. ochrus have great potential in frost-free climates. The importance of genotype x environment interactions in future breeding strategies is discussed.
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    URL: http://dx.doi.org/10.1007/BF00023512
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    Digestive enzyme activities and their distribution in the alimentary canal of larvae of the three extant lamprey families (1992)
    Springer
    Fish physiology and biochemistry 10 (1992), S. 1-10 
    Details
    ISSN: 1573-5168
    Keywords: larval lampreys ; exocrine pancreas ; lipase ; amylase ; chymotrypsin ; trypsin ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The activities of trypsin (EC 3.4.21.4), chymotrypsin (EC 3.4.21.1), lipase (EC 3.1.1.3) and amylase (EC 3.2.1.1) were measured in different regions of the alimentary tract of ammocoetes from each of the three extant lamprey families. In the southern hemisphere speciesGeotria australis (Geotriidae), and even more particularlyMordacia mordax (Mordaciidae), enzymatic activity was almost entirely confined to prominent diverticular extensions which arise at the oesophageal-intestinal junction. However, in the holarcticLampetra richardsoni (Petromyzontidae), which does not possess a diverticulum, the enzymatic activity was highest in the upper anterior intestine. It is not clear whether the presence of significantly higher amylolytic and lower lipolytic activities in the diverticulum ofG. australis than in the exocrine tissue of the other two species reflects interspecific differences in the composition of their diets. The capacity of exocrine tissue extracts for chymotryptic and tryptic digestion was assayed before and afterin vitro exposure to trypsin and enteropeptidase, their respective catalytic activators. Prior to exposure to these exogenous activators, both proteolytic enzymes were fully active inL. richardsoni, partially active inG. australis and totally inactive inM. mordax. Maximal chymotryptic activity was greater inM. mordax than inL. richardsoni andG. australis. In contrast, maximal tryptic activity was greater inL. richardsoni than inG. australis and was very low inM. mordax. Since trypsin is the only known activator of chymotrypsinogen, the negligible activity of trypsin inM. mordax would appear anomalous unless a trypsin inhibitor is present in the protopancreas of this species. Differences in the distribution of enzymatic activity within the alimentary tract of the three species is discussed in relation to proposed phylogenetic relationships amongst the extant lamprey families.
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    URL: http://dx.doi.org/10.1007/BF00004649
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    On the concepts of the taxonomic distinction, nature and essence of man (1992)
    Springer
    Human evolution 7 (1992), S. 41-47 
    Details
    ISSN: 1824-310X
    Keywords: evolution ; origin of man ; nature and essence of humanity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract It is proposed that the peculiarity of the specific nature of man consists in his polarisation into an ape-like «Australopithecoid» and specifically human sides. Its possible origin, as well as, differences between the concepts of the taxonomic distinction, species specific nature and essence of man are discussed.
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    Human evolution and epigenesis (1992)
    Springer
    Human evolution 7 (1992), S. 25-31 
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    ISSN: 1824-310X
    Keywords: Epigenesis ; evolution ; history
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436410
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    Japan and human evolutionary research (1992)
    Springer
    Human evolution 7 (1992), S. 85-91 
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    ISSN: 1824-310X
    Keywords: Japan ; Japanese ; evolution ; microevolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The trends in evolutionary research in Japan have largely changed through the introduction of new methodologies such as molecular genetics and multivariate statistics since the 1960’s. The development of ecology and primatology brought another new wave into fields of physical anthropology. This paper reviews briefly general trends in anthropological research now on-going in Japan. Microevolutionary studies of the Japanese and neighboring populations which have a long history in Japan will be reviewed in more detail.
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    URL: http://dx.doi.org/10.1007/BF02437456
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    Degradation of Synthetic Salmon Calcitonin in Aqueous Solution (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 1521-1523 
    Details
    ISSN: 1573-904X
    Keywords: salmon calcitonin ; stability ; kinetics ; peptide ; degradation ; pH–rate profile ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015839719618
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    Effect of Surfactant Phase in Perfluorocarbon Emulsification Efficiency (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 406-409 
    Details
    ISSN: 1573-904X
    Keywords: centrifugation ; emulsification ; perfluorocarbon ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of preparation temperature on the emulsification efficiency of perfluoro-3-butyltetrahydrofuran (FC-75) was investigated. Polyoxyethylene (POE) oleyl ether surfactants were used as the emulsifier(s) in a range of HLB values of 7.5 to 9.5. The emulsions were prepared by paddle mixing as a method of low-shear emulsification. After centrifugation of the resulting O/W emulsions, the volume of FC-75 which separated was utilized as a measure of the emulsification efficiency. In general, emulsions prepared at temperatures where the surfactant was in a lamellar-to-isotropic surfactant solution transition, Lα→ L3, displayed a better emulsification efficiency than those prepared with other surfactant phases.
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    URL: http://dx.doi.org/10.1023/A:1015807422517
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    The Influence of Sucrose, Dextran, and Hydroxypropyl-β-cyclodextrin as Lyoprotectants for a Freeze-Dried Mouse IgG2a Monoclonal Antibody (MN12) (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 266-270 
    Details
    ISSN: 1573-904X
    Keywords: monoclonal antibody ; lyophilization ; freeze-drying ; stability ; formulation ; cyclodextrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of lyophilization on the stability of a monoclonal antibody (MN12) was investigated. MN12 was freeze-dried in different formulations [without lyoprotectant or in the presence of sucrose, dextran, or hydroxypropyl-β-cyclodextrin (HPβCD)] and under varying conditions (with or without secondary drying). Subsequently, the monoclonal antibody was stored for 18 or 32 days at various temperatures (4, 37, or 56°C). For comparison, solutions of MN12 were stored under the same conditions. Regardless of the lyoprotectant used, precipitation and a concomitant reduction of the antigen-binding capacity by about 10% were observed upon recon-stitution of lyophilized MN12. HPβCD proved to be the most effective stabilizer to prevent degradation of lyophilized MN12 during storage. Compared with MN12 solutions, HPβCD-containing lyophilized MN12 cakes were more resistant to heat-induced charge alterations and loss of antigen-binding capacity.
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    URL: http://dx.doi.org/10.1023/A:1018905927544
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    Application of Electrospray Mass Spectrometry (ES-MS) for the Analysis of Monoclonal Antibody Fc Subunits (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 945-951 
    Details
    ISSN: 1573-904X
    Keywords: glycosylation ; mass Spectrometry ; monoclonal antibody ; protein characterization ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015817403321
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    Analysis of Hydroxyurea in Capsules and Aqueous Solution and Stability Study with Capillary Gas Chromatography and Thermionic (N–P) Specific Detection (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 115-118 
    Details
    ISSN: 1573-904X
    Keywords: capillary gas chromatography ; analysis ; stability ; urea derivative ; capsules ; mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A method for the analysis of hydroxyurea (HU) in solutions, powder, or capsules by use of capillary gas chromatography with N–P thermionic specific detection is described. Upon injection of an HU solution in a methanol and acetone mixture, the drug formed pyridine which was well separated from the internal standard (thiotepa) on a 30-m fused-silica, SE-30 capillary column with temperature programming. The peak height ratio versus concentration standard curves were linear with correlation coefficient ranging between 0.9942 and 0.9993. The coefficients of variation at 5, 25, and 50 µg/L were 7.2, 5.7, and 5.5%, respectively. Hydroxyurea was extracted from powder or capsule formulations with a mixture of methanol and acetone (50:50, v:v), and the percentage found of the label claim for 10 capsules ranged between 96.7 and 104.9 (mean = 100.1; CV = 2.7%). Further, this assay was used to examine the stability of hydroxyurea in aqueous solutions at 4, 23, and 45°C, and the apparent first-order rate constants observed at these temperatures were 0.06407, 0.08113, and 0.1293 day-1, respectively; the activation energy was 3011 cal · K-1 mol-1.
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    URL: http://dx.doi.org/10.1023/A:1018996130753
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    An Electrically Modulated Drug Delivery Device. III. Factors Affecting Drug Stability During Electrophoresis (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 312-315 
    Details
    ISSN: 1573-904X
    Keywords: controlled drug delivery system ; chronotherapeu-tics ; electrically modulated ; electrophoresis ; degradation of propranolol hydrochloride ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A number of factors affecting the stability of propranolol HC1 during electrophoretic control were investigated. It was found that significant degradation of propranolol HC1 and hydrolysis of water occurred when a current of 15 mA was used with platinized electrodes. This degradation was thought to be due to decomposition of propranolol HC1 at the electrodes. Degradation could be significantly reduced by using uncoated platinum electrodes and currents in the range of 0 to 2.5 mA, while still allowing control of drug delivery rates. Electrode reaction processes were found at high ionic strengths and high drug concentrations but were not thought to be associated with drug decomposition.
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    URL: http://dx.doi.org/10.1023/A:1015826532087
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    Solid-State Stability Testing of Drugs by Isothermal Calorimetry (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 939-944 
    Details
    ISSN: 1573-904X
    Keywords: calorimetry ; microcalorimetry ; stability ; kinetics, solid state ; degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new technique has been developed to calculate rapidly the solid-state room-temperature degradation rate of drugs and drug candidates. The technique utilizes measurements of the initial rate of heat output at several elevated temperatures by isothermal calorimetry and the degradation rate of the compound determined at a single elevated temperature by chromatography. The activation energies and degradation rates at 25°C calculated by conventional methods and by isothermal calorimetry are compared and discussed. The compounds studied were phenytoin, triamterene, digoxin, tetracycline, theophylline, diltiazem, and several proprietary ICI compounds.
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    URL: http://dx.doi.org/10.1023/A:1015865319250
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    Directional derivatives of optimal solutions in smooth nonlinear programming (1992)
    Springer
    Journal of optimization theory and applications 73 (1992), S. 27-45 
    Details
    ISSN: 1573-2878
    Keywords: Sensitivity ; stability ; nonlinear programming ; calmness
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We consider a smooth nonlinear program subject to perturbations in the right-hand side of the constraints. We do not assume that the unique solution of the original problem satisfies any qualification hypothesis. We suppose instead that the direction of perturbation satisfies the hypothesis of Gollan. We study the variation of the cost and, with the help of some second-order sufficiency conditions, obtain some conditions satisfied by the first term of the expansion of the solution. These conditions may vary depending on the existence of a Lagrange multiplier for the original problem.
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    URL: http://dx.doi.org/10.1007/BF00940076
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    Comparison of stability and control characteristics of two twin-lift helicopter configurations (1992)
    Springer
    Nonlinear dynamics 3 (1992), S. 199-223 
    Details
    ISSN: 1573-269X
    Keywords: Twin-lift helicopter ; nonlinear model ; stability ; feedback linearization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The stability and control characteristics of two twin-lift helicopter configurations are analyzed in this paper. In order to address the issue of configuration selection from a handling qualities viewpoint, their open-and closed-loop characteristics are compared. The two twin-lift configurations considered are the twin-lift with spreader bar and twin-lift without spreader bar. The nonlinear models describing the dynamics of these two configurations in the lateral/vertical plane are derived. The open-loop characteristics of the two systems are compared by linearizing the nonlinear models about a symmetric hovering equilibrium condition. The closed-loop characteristics of the two systems are compared using nonlinear controllers based on feedback linearization schemes. The performance of the resulting closed-loop systems in carrying out a typical twin-lift mission is evaluated through nonlinear simulation. Also, the effects of helicopter performance degradation and measurement errors on the overall system performance are discussed. [B] Matrix multiplying the control vector in the nonlinear model [B1] Matrix multiplying the control vector in the linear model [C] Matrix defining vector of variables to be controlled [C1] Damping matrix CijElement of the damping matrix e Parameter used in the linear model = M 1 h 1/I 1=M 2 h 2/I 2,/ft {f} Vector independent of controls in the nonlinear model g Acceleration due to gravity, ft/sec2 h1, h2Distance of tether attachment point to the center of gravity for helicopters 1 and 2, ft h Parameter used in the linear model, =h 1=h 2, ft h′ Distance between rotor hub and the helicopter center of gravity, ft h h/l′ H Distance of the load from the spreader bar c.g., ft H1, H2Length of tethers 1 and 2, ft IRMass moment of inertia of spreader bar, slug-ft2 I1, I2Roll moments of inertia of helicopters 1 and 2, slug-ft2 k′ Non-dimensional hub control moment coefficient KDDerivative gains KIIntegral gains KPProportional gains [Ki] Stiffness matrix KijElement of the stiffness matrix l′ Parameter used in the linear model, =H 1=H 2, ft L Spreader bar length, ft
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    On the stability of multi-layered fluids. Part I: analysis (1992)
    Springer
    Flow, turbulence and combustion 49 (1992), S. 307-334 
    Details
    ISSN: 1573-1987
    Keywords: stability ; linear-stability analysis ; multi-layered flow ; Orr-Sommerfeld equations ; interfacial conditions ; generalized eigenvalue problem ; air-water flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The linear stability of the Poiseuille flow of multi-layered different fluids, described mathematically by a system of Orr-Somerfeld differential equations, is investigated. A spectral method is used to rewrite this system into a generalized eigenvalue problem, which can be solved with the QZ-algorithm. Special attention is paid to the tractibility of the interfacial conditions of the stability problem. Since we will limit ourselves to a linear stability analysis, the analytical treatment of the interfacial conditions is simplified. Some results related to simple flow configurations are presented. The origin of certain regions of interfacial instability is explained by simple analytical reasoning.
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    URL: http://dx.doi.org/10.1007/BF00419978
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    Environmental networks, compensating life histories and habitat selection by white-footed mice (1992)
    Springer
    Evolutionary ecology 6 (1992), S. 1-14 
    Details
    ISSN: 1573-8477
    Keywords: evolution ; habitat selection ; life history ; litter size ; Ontario ; Peromyscus ; seasonality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Analysis of 6 years' data on a population of free-living white-footed mice documents both phenotypic and environmental control of litter size. Litter size was positively correlated with maternal body size. Maternal size depended upon both seasonal and annual variation. Paradoxically, the proportion of small versus large litters varied among habitats independently of the effects of body size. The result is an influence of habitat on life history that yields patterns of reproduction and survival opposite to the predictions of demographic theory. The habitat producing the largest litters had a relatively high ratio of adult/juvenile survival. Litter size was small in the habitat where the adult/juvenile survival ratio was smallest. All of these anomalous patterns can be explained through density-dependent habitat selection by female white-footed mice. Life-history studies that ignore habitat and habitat selection may find spurious correlations among traits that result in serious misinterpretations about life history and its evolution.
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    URL: http://dx.doi.org/10.1007/BF02285330
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