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  • 1
    Digitale Medien
    Digitale Medien
    Comment on biomass diversity in ecology (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 967-969 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract It is observed that a dynamical continuity equation for biomass distribution yields the asymptotic steady-state exponential dependencen=A exp( $$ - m/\bar m$$ ) exhibited by certain fishery data, wherem is the biomass of an individual,n is the number of individuals per unit biomass interval, andA, $$\bar m$$ are positive constants. This dynamical approach to biomass distribution is an alternative to the global maximization principle proposed recently by Lurié and Wagensberg.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462083
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  • 2
    Digitale Medien
    Digitale Medien
    Physik der Selbstorganization und Evolution (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 971-972 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462084
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  • 3
    Digitale Medien
    Digitale Medien
    Announcements (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 973-974 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462085
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  • 4
    Digitale Medien
    Digitale Medien
    Random selection—A simple model based on linear birth and death processes (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 11-17 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Linear birth and death processes are used to derive simple expressions for sequential extinction times and gene fixation probabilities in asexual populations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463720
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  • 5
    Digitale Medien
    Digitale Medien
    On the measurement of shapes (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 1-10 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract We are here concerned with the functionf which assigns to each pointP of an object the numberf(P) which is the shortest distance fromP to the border. This function appears in various guises in diverse biological studies. The functionf(P) is itself a measure of shape—or more precisely, an infinite set of measures, one for each point (and hence, in view of its geometric definition, usually in a form inconvenient for use). Thus in this paper we sought a reasonable representative of this infinite set of measures, namely themean of the numbersf(P) asP ranges over all points of the entity. Computability studies are developed for various classes of shapes. For example, (1) the mean for a lamina bounded by a polygon circumscribable about a circle of radiusr isr/3; (2) the mean for a domain bounded by a polyhedron circumscribable about a sphere of radiusr isr/4. The transition from pointwise to piecewisef(P), especially in the non-convex case, requires working with inequalities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463719
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  • 6
    Digitale Medien
    Digitale Medien
    Traveling bands of chemotactic bacteria in the context of population growth (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 19-40 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A mathematical model for traveling bands of motile and chemotactic bacteria in the presence of cell growth and death is examined. It is found that asymptotic traveling wave solutions exist in the absence of chemotaxis, due to the balance of growth, death and random motility. Thus random motility confers the ecological advantage of population propagation through migration into nutrient-rich regions. The presence of chemotaxis amplifies this advantage by moving more cells into higher nutrient concentration regions, resulting in larger and faster bands. Therefore there seem to be two types of traveling bands that can be attained by chemotactic bacteria in the presence of growth and death: (1) these growth/death/motility bands; and (2) pure chemotactic ‘Keller-Segel'-type bands. Comparison to experimental observations by Chapman in 1973 indicate that the latter seem to be formed. The relationship between these two types of solution is at present uncertain. The growth/death/motility bands may have relevance on longer time or distance scales characteristic of microbial ecological systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463721
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  • 7
    Digitale Medien
    Digitale Medien
    A mathematical model of the pathological functional state of the oxygen transport system (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 115-125 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Based on the principle of minimum power, a mathematical model of the pathological functional state of the oxygen transport system is presented. The model is used to determine the optimal functional parameters of the oxygen transport system in hyperthyroidism, anemia and hypertension. Theoretical results are compared with clinical data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463725
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  • 8
    Digitale Medien
    Digitale Medien
    Stability in an insect-pathogen model incorporating age-dependent immunity and seasonal host reproduction (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 139-153 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A modified SIRS model is developed as a framework for the study of epizootiological dynamics in an insect-pathogen system. Linearized stability analysis reveals that the system with one immune and one susceptible host class can exhibit stable, periodic or unstable behavior depending on model parameters. In general, high pathogenicity, short pathogen propagule lifespan and high host reproductive rate are stabilizing influences. Pathogen transmissibility and propagule production/host do not influence local stability. The effect of seasonal host reproduction is studied because most insect hosts are seasonal in temperate climates. The basic stability dependence on model parameters holds except as modified by the length of the reproduction interval. The results of this study are compared with the recent work of Anderson and May.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463727
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  • 9
    Digitale Medien
    Digitale Medien
    Random predator-prey interactions in a varying environment: Extinction or survival (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 175-184 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The random predator-prey type interactions of the population species in a random varying environment have been investigated. The Fokker-Planck equation for the transition probability, corresponding to the stochastic differential equations established from Lotka-Volterra equations by the introduction of randomness and variability, has been integrated in the form of a path integral. The transition probabilities for extinction or survival of one or several species have been approximately evaluated and investigated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463729
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  • 10
    Digitale Medien
    Digitale Medien
    Coexistence of two microbial populations competing for a renewable resource in a non-predator-prey system (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 155-174 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract If two microbial populations compete for a single resource in a homogeneous environment with time invariant inputs they cannot coexist indefinitely if the resource competed for is not renewed by biological activity within the system. Mathematical studies have shown that in a predator-prey system, where the resource (prey) is self-renewing, the two competitors (predators) can coexist in a limit cycle. This suggests that if the resource competed for is renewed by biological activity within the system coexistence can occur in any microbial system provided that it exhibits the same features as, but without being, a predator-prey one. A food chain involving commensalism, competition and amensalism is presented here. Two subcases are considered. It is only when maintenance effects are taken into account that coexistence, in limit cycles, can occur for this system. Limit cycle solutions for the system are demonstrated with the help of computer simulations. Some necessary conditions for coexistence are presented, as are some speculations regarding the possible physical explanations of the results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463728
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  • 11
    Digitale Medien
    Digitale Medien
    Adaptive regulation of wall shear stress optimizing vascular tree function (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 127-137 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The branching structure of the mammalian arterial tree has been known to be close to that of an optimal conduit system of the minimum work model characterized as the branch system of constant wall shear rate. The physiological mechanism producing such construction was considered to be based on the local response of arterial caliber induced by the wall shear stress (shear rate × blood viscosity) and thereby maintaining this stress constant, which was previously observed at the canine common carotid artery shunted to the external jugular vein. The stress levels at various parts of the arterial system estimated from available data fell within ±50% of the mean (15 dyn/cm2), which was consistent with the value predicted from the model. Theoretical analyses on the cost function of the model indicated that the suspected variation of shear rate levels in the arterial tree due to the anomalous changes in blood viscosity which might bring about 3- to 4-fold differences between the minimum and maximum shear rates would cause less than 10% increase in the total energy cost. It was concluded that a local adaptive response to wall shear stress is the mechanism which effectively optimizes the design of the arterial tree.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463726
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  • 12
    Digitale Medien
    Digitale Medien
    Population dynamics with age- and time-dependent birth and death rates (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 185-185 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463730
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  • 13
    Digitale Medien
    Digitale Medien
    A unifying concept for the amino acid code (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 187-203 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The structure of the genetic code is related to a Gray code, which is a plausible theoretical model for an amino acid code. The proposed model implies that the most important factor in shaping the code was the effects of mistakes in translation, not effects of mutations. Another possible implication is that the preservation of stiffness and flexibility at appropriate places in a protein chain is as important in protein structure as the appropriate placement of hydrophilic (external) and hydrophobic (internal) residues. Other results are a simple conceptualization of the relationships among the 20 amino acids and their relations to their codons. The detailed relationships are summarized in the following ‘similarity alphabet’: ala, thr, gly, pro, ser; asp, asn, glu, gln, lys; his, arg, trp, tyr, phe; leu, met, ile, val, cys; (ATGPS DNEQK HRWYF LMIVC in the one-letter code). This alphabet falls into four groups of amino acids: small, external, large, internal. The approximate relation of the groups to their codons is expressed as: the first base of a codon controls size—a purine means a small amino acid, a pyrimidine means large; the middle base controls cloisterednes—purine means external, pyrimidine means internal. These relationships express the minimum change principle upon which the code appears to be founded.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460068
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  • 14
    Digitale Medien
    Digitale Medien
    Concentration-dependent diffusion coefficient and dissipative structures (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 269-282 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A theoretical study of the Brusselator model with non-uniform distribution of component A and a concentration-dependent diffusion coefficient has been performed. Numerical simulation reveals that a variable diffusion coefficient alters the bifurcation pattern and the stability properties of the steady-state as well as periodic solutions. A simple approximate method, based on one-point collocation, has been proposed to analyze the bifurcation phenomena for the case of fixed boundary conditions and low system size.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460074
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  • 15
    Digitale Medien
    Digitale Medien
    Cuttrees in the topological analysis of branching patterns (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 283-294 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract In this paper the effects of the occurrence of cut trees in the topological analysis of branching patterns have been studied. It is assumed that branches are removed at random from the trees. We prove that, for both the segmental and terminal growth models, the probability distributions of the cut trees are identical to those of complete trees.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460075
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  • 16
    Digitale Medien
    Digitale Medien
    Capillary operators (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 247-268 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The goal of this work is an examination of capillary exchange models as mathematical operators. The concentration function relations for the Krogh cylinder of a single capillary, basic to many organ models, are studied via the theory of operators on the Lebesgue normed spacesL p[0,∞], (1〈-p〈-∞). A discussion is included of theL p -normsvis-à-vis the coefficient of variation currently used in finding capillary parameters and evaluating parameter searches. The capillary model determines two operators on the space of locally integrable functions: O K (relating extravascular concentration to intravascular) and K a, k (relating intravascular concentration to input), wherek is the ratio of permeabilitysurface area (PS) to extravascular volume, and α is the ratio of PS to flow. These operators are shown to induce contractive (‖O K ‖ p 〈-1, ‖K a, k ‖ p 〈-1), isotone, linear operators onL p . The uniform convergence relation $$K_{a,k} = \mathop {\lim _{(p)} }\limits_{N \to \infty } \left( {\sum\limits_{n = 0}^N {P_n (a)O_k^n } } \right)$$ (as operators onL p) is derived, whereP n (a) is the Poisson probabilitye −a a n /n!. For the important special cases ofp=∞, 1, 2 the norms are found (‖Ok‖=‖Ka,k‖p=1). Consideration is also given to the norms and operators when the functions involved are limited to a finite interval of time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460073
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  • 17
    Digitale Medien
    Digitale Medien
    Long-term memory modules (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 295-326 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract One particular kind of structure offers possible explanations, for long-term memory, efficient consolidation of stored information from the environment, clustering of data strings and multimodal functioning. It is a possible model for pieces of neural structure and its use offers a uniform method for both studying and constructing an extensive class of mechanisms.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460076
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  • 18
    Digitale Medien
    Digitale Medien
    Properties of levenshtein metrics on sequences (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 327-332 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Levenshtein dissimilarity measures are used to compare sequences in application areas including coding theory, computer science and macromolecular biology. In general, they measure sequence dissimilarity by the length of a shortest weighted sequence of insertions, deletions and substitutions required, to transform one sequence into another. Those Levenshtein dissimilarity measures based on insertions and deletions are analyzed by a model involving valuations on a partially ordered set. The model reveals structural relationships among poset, valuation and dissimilarity measure. As a consequence, certain Levenshtein dissimilarity measures are shown to be metrics characterized by betweenness properties and computable in terms of well-known measures of sequence similarity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460077
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  • 19
    Digitale Medien
    Digitale Medien
    Announcement (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 337-337 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460079
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  • 20
    Digitale Medien
    Digitale Medien
    Commensalism of methane-producing and motile aerobic bacteria in certain freshwater wetlands (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 333-336 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract It is pointed out that the methane flux measured experimentally for certain ponds and swamps is quantitatively consistent with a commensal dependence of Methanobacteria on O2-chemotactic motile aerobic bacteria. The Methano species is thereby shielded from oxygen and provided with carbon dioxide for the anaerobic production of methane.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460078
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  • 21
    Digitale Medien
    Digitale Medien
    Persistence in stochastic food web models (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 357-370 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A sufficient condition is given for stochastic boundedness persistence of a top predator in generalized Lotka-Volterra-type stochastic food web models in arbitrary bounded regions of state space. The main result indicates that persistence in the corresponding deterministic system is preserved in the stochastic system if the intensities of the random fluctuations are not too large.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462011
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  • 22
    Digitale Medien
    Digitale Medien
    Evolution of cannibalism in an age-structured population (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 371-377 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract One of Bobisud's models for the evolution of cannibalism is reanalyzed by applying the method of finding evolutionarily stable strategies (or ESS's). It is demonstrated that ‘no cannibalism’ never will be an ESS if the initial rate of cannibalism is too large. It is further demonstrated that individual selection may even result in the evolution of cannibalism during food abundance. Some empirical case studies are briefly discussed in relation to this model.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462012
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  • 23
    Digitale Medien
    Digitale Medien
    An algorithm to equiprobably generate all directed trees withk labeled terminal nodes and unlabeled interior nodes (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 379-387 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A computer algorithm is presented which equiprobably generates any member of the set of all directed trees withk labeled terminal nodes and unlabeled interior nodes. The algorithm requires roughlyk 2 /2 storage locations. The one-time initialization requiresO(k 2 ) time, while generating each tree requiresO(k) time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462013
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  • 24
    Digitale Medien
    Digitale Medien
    Pattern recognition in several sequences: Consensus and alignment (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 515-527 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The comparison of several sequences is central to many problems of molecular biology. Finding consensus patterns that define genetic control regions or that determine structural or functional themes are examples of these problems. Previously proposed methods, such as dynamic programming, are not adequate for solving problems of realistic size. This paper gives a new and practical solution for finding unknown patterns that occur imperfectly above a preset frequency. Algorithms for finding the patterns are given as well as estimates of statistical significance.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459500
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  • 25
    Digitale Medien
    Digitale Medien
    Pattern recognition in genetic sequences by mismatch density (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 501-514 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A new development is introduced here in the use of dynamic programming in finding pattern similarities in genetic sequences, as was first done by Needleman and Wunsch (1969). A condition of pattern similarity is defined and an algorithm is given which scans any set of similarities and screens out those which fail to meet the condition. When the set to be scanned contains every pair of segments, one from each of two given sequences of lengthsm andn (i.e. every possible location for a pattern similarity), then it completes the scan in a number of computational steps proportional tom·n, leaving those pairs of segments which satisfy the similarity condition. The algorithm is based on the concept of match density, as suggested by Goad and Kanehisa (1982).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459499
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  • 26
    Digitale Medien
    Digitale Medien
    Distinguished words in data sequences: Analysis and applications to neural coding and other fields (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 529-543 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract This paper concerns sequences of letters in which certain “distinguished” words are of interest. Such sequences arise as data in numerous fields including genetics and neuroscience. A probability distribution is given for the number of occurrences of a chosen word in a randomized sequence of letters. Such words are considered “favored” if they occur more than expected at random. Favored words have been discovered in nerve impulse trains and may reflect a neural coding scheme.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459501
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  • 27
    Digitale Medien
    Digitale Medien
    Searching the protein sequence database (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 545-552 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract As the volume of protein sequence data grows, rapid methods for searching the protein sequence database become of primary importance. Rigorous comparison of sequences is obtained with the well-known dynamic programming algorithms. However, these algorithms are not rapid enough to use for routinely searching the entire database. In this paper we discuss some methods that can be used for rapid searches.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459502
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  • 28
    Digitale Medien
    Digitale Medien
    Algorithms for computing evolutionary similarity measures with length independent gap penalties (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 553-566 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract We give algorithms for computing the extent of similarity between two or three sequences of letters. The similarity measures we consider include a penalty for inserting gaps within the sequence in order to enhance similarity. The magnitude of the penalty for gaps is assumed to be independent of their size in order to accommodate certain biological applications. Our algorithm for three sequence comparisons, which is based on solving a system of recursive equations, improves upon the efficiency of existing methods. Although the system of recursive equations utilized by the algorithm is quite complicated as it stands, it has none the less been simplified by appeal to combinatorial considerations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459503
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  • 29
    Digitale Medien
    Digitale Medien
    Line geometries for sequence comparisons (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 567-577 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Well-known dynamic programming algorithms exist for comparing two finite sequences inO(N 2) time and storage, whereN is the common sequence length. Extensions to the comparison ofM finite sequences requireO((2N) M) time and storage, making such algorithms difficult even forM=3. A simple generalization of the sequences makes it possible to obtain some results about the geometry of sequence alignments. These ideas suggest heuristic approaches to problems of comparing several sequences. IfM sequences are known to be related by a binary tree, they can be aligned inO(MN 2) time andO(N 2+NM) storage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459504
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  • 30
    Digitale Medien
    Digitale Medien
    The uniqueness of protein sequences. Uniqueness diagrams for the Dayhoff file—1984 (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 661-672 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Protein sequences of the Dayhoff databank of 1984 have been analyzed to evaluate the occurrences of the 400 dipeptides and 8000 tripeptides. Expected values and standard deviations for the di- and tripeptides were determined by Monte Carlo and binomial approximation. A condensed format containing this information, labeled a uniqueness diagram, is presented and made available in the form of a microfiche.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459509
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  • 31
    Digitale Medien
    Digitale Medien
    The characteristics method applied to the study of muscle dynamics (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 827-844 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract In two-state sliding filament models of muscle contraction a partial differential equation must be solved to find the cross-bridge distribution functionn(x, t). In this paper the analytical form of this function is obtained by integration along the characteristic line and special cases are presented in which the explicit expression forn(x, t) can be completely determined. These analytical solutions provide a direct mathematical connection between the microscopic contraction parameters contained in the kinetic theories and macroscopic muscle dynamics and are thus used to investigate what parameters influence the transient contractile tension in typical experimental conditions. The results of this investigation are consistent with relevant aspects of muscle physiology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462072
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  • 32
    Digitale Medien
    Digitale Medien
    Beyond the binary case in random nets (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 845-857 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Experiments on random binary, ternary, etc. (P=2, 3,…, 10) switching nets are reported. Behavioral cycle lengths are examined as functions of output variety,P, input connectance,K, and net size,N. Overall, output variety appears an influential, well-behaved net property. Strong, but well-behaved interactions appear among net variables. In high connectance nets, median cycle length grows approx. asP N/2. Other factors constant, one-connected nets show the shortest cycles, and connectance effects appear to converge asymptotically aroundN. Data for cycle length as a function of net size suggest a concavity not compatible with the Kauffman “square root law” (Kauffman, 1969). Evidence of a positive relationship between cycle length and run-in length is found in two-input nets; weaker evidence is obtained that in higher connectance nets this relationship becomes negative in sign. The “modular complexity” ofP〉2 nets is examined briefly.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462073
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  • 33
    Digitale Medien
    Digitale Medien
    Influence of landscape on the spread of an infection (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 869-877 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The influence of topographical situation on the spread of infection is studied. The investigation is based on a multigroup model. The population under consideration is thought to be divided into subpopulations living in regions that are separated from each other by natural barriers (mountains). Infection is carried from one region to another by migrating infectives. Migration is possible only along the river system so that the structure of the epidemiological network is that of a symmetric tree. The results allow comparison of the velocity of propagation of the epidemic for different geographical situations and allow quantification of the “channel-effect”, according to which mountainous regions are channels rather than barriers to the spread of an epidemic.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462075
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  • 34
    Digitale Medien
    Digitale Medien
    A catastrophe theoretic model of heat regulation in homeothermic animals (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 81-102 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The temperature regulation in homothermic animals is an example of a negative feedback system. It shows sudden changes of parameter values, and therefore suggests the use of catastrophe theory for its description. This paper reports on work done on the human temperature regulation mechanism to shows that the five-dimensional dual butterfly catastrophe model is sufficient for its description. Nearly all experiments reported in the literature overlook the dynamic multiparametric nature of the process. Use of catastrophe theory, on the other hand, shows that one cannot find a model with fewer than five parameters for such a system. From work by Benzinger and Kitzinger, the exact shape of part of the corresponding bifurcation set is determined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463723
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  • 35
    Digitale Medien
    Digitale Medien
    Pulse wave velocities in the aorta (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 103-114 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract This paper is an analytical study on the pulse wave velocities in the aorta. In conformity to a physiologic state of loading, the distensibility of the vessel wall has been accounted for. The wall material is treated by using the theory of large elastic deformations. The orthotropicity of wall tissues and the effect of the surrounding tissues have been incorporated in the analysis which is based on the use of the strain energy function suggested by Vaishnavet al. Numerical values of the wave velocities of the canine middle descending thoracic aorta are computed by using the derived analytical expressions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463724
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  • 36
    Digitale Medien
    Digitale Medien
    Single-salt behavior of a symmetrical 4-site channel with barriers at its middle and ends (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 41-80 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The theory of a symmetrical 3-barrier, 4-site, single-filing ionic channel is developed. The model goes beyond earlier models by including additional sites, as well as barriers which need not be symmetrical in the applied field, and contains the earlier models as special cases. It is itself a special case of the most general 4-site model, which has 5 barriers. By considering the barriers at the mouth and middle of the channel to be sufficiently larger than the barriers separating the sites in each channel half, these barriers can be neglected; thus this case reduces to a 3-barrier model where the sites in each channel half can then be assumed to be in equilibrium with each other. The alternative 3-barrier, 4-site case, where the barrier between the sites is considered to be larger than that at the mouth of the channel, is considered elsewhere. Pure cation permeation is considered and only single-salt properties of the system are analyzed, namely occupancy, conductance, flux ratio exponent and current-voltage relation. The concentration dependences of these properties are computed and interrelated and, where possible, also given in analytical form. The mathematical relations are obtained for a channel which is symmetrical around its middle, which is the appropriate assumption for the gramicidin channel. However, the barriers themselves are allowed to be asymmetric with respect to the potential dependence, which has been found to be essential for gramicidin. Mathematically, a straight-forward matrix formulation is used; but a general theoretical method is presented for reducing a complex model (with more than 2 sites) to a simpler cases when equilibrium exists across one or several barriers, as is often the cases. This method is a prototype which makes analytical solutions of complex barrier models possible in many cases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02463722
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  • 37
    Digitale Medien
    Digitale Medien
    Four-urn catenary model for excretion (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 219-227 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A chain-like arrangement of four urns (a catenary system) into which different color balls (white, corresponding to radio atoms, and black, corresponding to stable atoms) are being transferred is used to simulate the transport of atoms down the GI tract of man and animals. Into the first urn (stomach) are placedw o white balls andr black balls while in the 2nd (small intestines) and 3rd (large intestines) urn, onlyr blacks are put in, with no whites. A sample of sizer is transferred from the 1st, 2nd and 3rd urns to the 2nd, 3rd and 4th (infinite universe) urns. From the random variable difference equations the first and second moments for the distribution of the number of radio atoms present in each urn are obtained. The variance of the contents of radioatoms in the excretion urn is
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460070
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  • 38
    Digitale Medien
    Digitale Medien
    A general solution for the steady-state kinetics of immobilized enzyme systems (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 229-234 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A power series solution is presented which describes the steady-state concentration profiles for substrate and product molecules in immobilized enzyme systems. Diffusional effects and product inhibition are incorporated into this model. The kinetic consequences of diffusion limitation and product inhibition for immobilized enzymes are discussed and are compared to kinetic behavior characteristic of other types of effects, such as substrate inhibition and substrate activation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460071
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  • 39
    Digitale Medien
    Digitale Medien
    Model of diffusion of oxygen to spheroids grown in stationary medium —I. Complete spherical symmetry (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 205-217 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The use of spheroids as a tumor model has become commonplace since it was discovered that many cell lines can form spheroids when grown on a surface to which the cells cannot attach. This culture system complicates experiments which depend on oxygen supply because the oxygen concentration in the vicinity of a stationary spheroid has not been well defined. We present in this paper solutions to the oxygen diffusion equation for simple geometries: a spheroid in an infinite stationary medium and in a finite spherical stationary medium. Comparison of these solutions provides an estimate of the oxygen supply to a spheroid in a Petri dish. We show that typical spheroids can be expected to cause a substantial depletion of the oxygen in the nearby medium. Any disturbance of the medium or the spheroids will temporarily increase the oxygen supply. We provide a method for estimating the rate of return to equilibrium in the finite cases. These results indicate that the oxygen supply to stationary spheroids can be altered temporarily by small movements or changes in temperature which cause convection currents, or permanently by changes in the depth of the medium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460069
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  • 40
    Digitale Medien
    Digitale Medien
    Stability of spatially heterogeneous steady-state distributions of oxygen-chemotactic aerobic/anaerobic bacteria (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 235-246 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Alternative sufficient conditions are derived that guarantee the stability of spatially heterogenous steady-state distributions of motile aerobic bacterial populations attracted chemotactically by oxygen, motile anaerobic populations repelled by oxygen, and the oxygen concentration itself through a stationary aqueous medium. In particular, it follows from the latter criteria that the heterogeneous steady-state distributions for cylindrical regions with arbitrary cross-sections, uniform depth and mixed Dirichlet-Neumann boundary conditions on the oxygen concentration (appropriate to certain still-water bodies in nature) are stable with respect to arbitrary perturbations in the bacteria cell and the oxygen distributions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02460072
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  • 41
    Digitale Medien
    Digitale Medien
    Dynamical machinery of a biochemical clock (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 339-355 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Closed positive feedback loops of catalytic reactions between macromolecules, or hypercycles, provide a kinetic mechanism whereby each Species serves to catalyze selfreproduction of its successor in the loop. Hypercycles of five members or more evolve into limit cycles characteristic of a biochemical clock. Computer study of the coupled non-linear differential equations which describe these systems shows that the periodT n of then-species limit cycle is given byT n=nτn, where τn is an elemental repeat period reflecting translational time invariance. Analytic solutions of the equations are developed so that the time evolution of elementaryn-hypercycles can be traced in dynamical detail. It is shown that the magnitude of τn is, to good approximation, a linear function ofn. For a givenn, τn is a very sensitive function of the relative concentration a given member of the loop has at the time its predecessor dominates the state of the hypercycle. These concentrations decrease with increasingn. Aroundn=15 they become so small that elementary hypercycles become unstable against disruptive concentration fluctuations. Species concentrations for more realistic hypercycles tend not to be as small, so that the present estimate of a maximum number of components is a lower bound.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462010
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  • 42
    Digitale Medien
    Digitale Medien
    Stability analysis of a stochastic model for biomolecular selection (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 399-406 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The technique of the probability generating function is used to derive the stochastic differential equations for a nonlinear model based on Eigen and Schuster's theory of biomolecular selection and evolution. The stabilities of various steady states are analyzed by using the linear stability approximation. The instability of a small starting population is investigated numerically. The minimum starting populations required for steady-state survival are then estimated for a wide range of parameters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462015
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  • 43
    Digitale Medien
    Digitale Medien
    Computer simulation of the geometry of the human bronchial tree (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 389-398 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Some morphological features of the human bronchial tree were simulated by computergenerated trees. The trees were ordered by the methods of Horsfield and Strahler. Delta, the difference between the Horsfield orders of the two branches at a bifurcation, was determined by pseudorandom numbers generated according to a distribution of probabilities defined on input. By trial and error a distribution was found which resulted in trees being generated with average Strahler order branching ratios of 2.82, similar to a real bronchial tree. Branching angles and length ratio could also be defined on input. By varying these input parameters it was found that the form of the tree was quite sensitive to them, and that by a suitable choice the intrasegmental part of the bronchial tree could be simulated. It is concluded that branching ratio, length ratio, mean branching angles and distribution of delta are controlled within tight limits in the bronchial tree, and this may support the concept of optimal design.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462014
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  • 44
    Digitale Medien
    Digitale Medien
    The mathematical modeling of entrained biological oscillators (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 407-422 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract In this paper perturbation methods are used for the mathematical analysis of coupled relaxation oscillators. This study covers entrainment by an external periodic stimulus as well as mutual entrainment of coupled oscillators with different limit cycles. The oscillators are of a type one meets in the modeling of biological oscillators by chemical reactions and electronic circuits. Special attention is given to entrainment different from 1∶1. The results relate to phenomena occurring in physiological experiments, such as the periodic stimulation of neural and cardiac cells, and in the non-regular functioning of organs and organisms, such as the AV-block in the heart.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462016
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  • 45
    Digitale Medien
    Digitale Medien
    A stochastic model of the effects of ionizing radiation on mammalian cellsin vitro (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 423-446 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A new, more realistic model of the action of ionizing radiation on mammalian cells growingin vitro is presented. Although this model requires a large number of parameters, these are linked to biologically observable quantities rather than being abstract sensitivities, as had previously been the case. Three different stochastic processes are required: {X(t);t ∈ [0, τ]}, representing damage alterations during irradiation; {(X(t), S(t));t ∈ [τ, τ+T D]}, representing changes in both damageX(t) and cell cycle positionS(t) during the post-irradiation cell cycle; and {N x(t);t ∈ [0,T G]}, representing the subsequent colony growth process conditioned on the value ofX(τ+T D). The assumptions used to define these processes extend a previous model of short term DNA damage formation and repair (Nelson S. J. 1982,Radiat. Res. 92, 120–145) to include the influence of cell cycle progression on damage in the irradiated cell and the effect of permanent inherited damage on the daughter cells' colony growth pattern. Expressions corresponding to commonly measured radiation effects are derived from the model and compared with predictions from previous models. It is found that these previous models oversimplified the mechanism of radiation action because they did not adequately represent repair during irradiation, the influence of radiation-induced cycle delays and damage inheritance by any daughter cells. Suggestions are then made for ways in which the new model can be used to test the importance of these effects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462017
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  • 46
    Digitale Medien
    Digitale Medien
    Foreword (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 461-465 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459496
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  • 47
    Digitale Medien
    Digitale Medien
    Margaret Oakley Dayhoff 1925–1983 (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 467-472 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459497
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  • 48
    Digitale Medien
    Digitale Medien
    A stochastic model of bacterial spore germination (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 447-460 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A stochastic approach is utilized to develop a model equation capable of describing the time course of germination in a sample of bacterial spores. The time required by a spore to complete the change characteristic of germination consists of an initial interval of no change followed immediately by the duration of the change itself. The experimental basis of the proposed model is the observation that each of these time intervals is distributed over a range of values in a spore sample. Mixed continuous and discrete probabilities are employed in arriving at an average single-spore germination curve which, to a different scale, describes the sample in time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462018
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  • 49
    Digitale Medien
    Digitale Medien
    General methods of sequence comparison (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 473-500 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Mathematical methods for comparison of nucleic acid sequences are reviewed. There are two major methods of sequence comparison: dynamic programming and a method referred to here as the regions method. The problem types discussed are comparison of two sequences, location of long matching segments, efficient database searches and comparison of several sequences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459498
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  • 50
    Digitale Medien
    Digitale Medien
    A non-metric sequence alignment program (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 579-590 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract An algorithm for nucleic acid and protein sequence alignment is presented. It is a non-metric local similarity minimal-difference algorithm and in the current implementation, assembles the matching regions found into a pseudo-global format. Its strengths are its speed of execution and the especially convenient presentation of its output. The algorithm is intended for use in sequence melding and local (small-region) similarity searching. It is not designed to replace a metric Needleman-Wunsch-Sellers-type similarity algorithm. The program is written in FORTRAN and is designed to be easily transportable to a variety of computer systems.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459505
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  • 51
    Digitale Medien
    Digitale Medien
    RNA secondary structures and their prediction (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 591-621 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract This is a review of past and present attempts to predict the secondary structure of ribonucleic acids (RNAs) through mathematical and computer methods. Related areas covering classification, enumeration and graphical representations of structures are also covered. Various general prediction techniques are discussed, especially the use of thermodynamic criteria to construct an optimal structure. The emphasis in this approach is on the use of dynamic programming algorithms to minimize free energy. One such algorithm is introduced which comprises existing ones as special cases.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459506
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  • 52
    Digitale Medien
    Digitale Medien
    On the syntactic structure of protein sequences and the concept of grammar complexity (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 641-659 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract It is shown that the concepts of grammar complexity and syntactic structure provide a useful mathematical framework for the investigation of some current problems in protein structure. Grammar complexity gives a measure of the degree of aperiodicity of a sequence and also an optimization criterion for evaluating amino acid categorizations. Three systems of amino acid categorization are compared in relation to their value for describing molecular architecture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459508
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  • 53
    Digitale Medien
    Digitale Medien
    A vector representation for amino acid sequences (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 623-639 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A scheme for representing amino acids as vectors in the plane is presented and justified. The two dimensions of the plane are size and hydrophobicity. The vector representation is then applied to generate a consensus sequence for some sets of homologous proteins. A figure of merit for the degree of homology of a set of sequences results from the analysis. Some other applications of the scheme are considered also. This work grew from ideaseeds planted by Margaret Dayhoff's work in theAtlas of Protein Structure and Sequence. It is with gratitude that I dedicate this paper to her memory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459507
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  • 54
    Digitale Medien
    Digitale Medien
    Editorial: Software survey section (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. I 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459512
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  • 55
    Digitale Medien
    Digitale Medien
    Mathematical tools for molecular genetics data: An annotated bibliography (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 699-744 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract An annotated bibliography of mathematical and computer analyses of protein and nucleic acid sequences is presented. The major subject areas represented are the determination of sequences, restriction mapping, similarity searching, sequence alignment, codon utilization, statistical analysis, information theoretic analysis, the construction of secondary and tertiary structure and DNA topology.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459511
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  • 56
    Digitale Medien
    Digitale Medien
    A distance geometry program for determining the structures of small proteins and other macromolecules from nuclear magnetic resonance measurements of intramolecular1H−1H proximities in solution (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 673-698 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract DISGEO is a new implementation of a distance geometry algorithm which has been specialized for the calculation of macromolecular conformation from distance measurements obtained by two-dimensional nuclear Overhauser enhancement spectroscopy. The improvements include (1) a decomposition of the complete embedding process into two successive, more tractable calculations by the use of “substructures”, (2) a compact data structure for storing incomplete distance information on a structure, (3) a more efficient shortest-path algorithm for computing the triangle inequality limits on all distances from this information, (4) a new algorithm for selecting random metric spaces from within these limits, (5) the use of chirality constraints to obtain good covalent geometry without the use ofad hoc weights or excessive optimization. The utility of the resultant program with nuclear magnetic resonance data is demonstrated by embedding complete spatial structures for the protein basic pancreatic trypsin inhibitor vs all 508 intramolecular, interresidue proton-proton contacts shorter than 4.0 Å that were present in its crystal structure. The crystal structure could be reproduced from this data set to within 1.3 Å minimum root mean square coordinate difference between the backbone atoms. We conclude that the information potentially available from nuclear magnetic resonance experiments in solution is sufficient to define the spatial structure of small proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02459510
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  • 57
    Digitale Medien
    Digitale Medien
    The enzymatic neuron as a reaction-diffusion network of cyclic nucleotides (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 765-783 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Recent evidence suggests that the cyclic nucleotides play a central role in the intracellular processing of neural signals. The dynamics of this system may be seen as a realization of the enzymatic neuron model. Enzymatic neurons are formal neurons which map binary afferent signals into patterns of excitation across an abstract membrane. The distribution of enzyme-like elements called excitases enables a set of local threshold functions to determine the firing activity of the neuron. This paper analyzes the basic properties of enzymatic neurons in a simple continuous-time framework, and shows how they may be presented as reaction-diffusion networks which model the cyclic nucleotide system. We present the results of computer simulations of this neuron and discuss its implications for selectional learning and its relation to conventional two-factor systems. One fundamental property of the reaction-diffusion neuron is its so-called “double-dynamics” property; examination of this property and its contribution to the computing power of the neuron provides some insight into the obscure relation between microscopic and macroscopic models of computation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462070
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  • 58
    Digitale Medien
    Digitale Medien
    Stieltjes integration and differential geometry: A model for enzyme recognition, discrimination, and catalysis (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 745-764 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A model for enzymic catalysis is presented using the mathematical theories of differential geometry and Stieltjes integration. The Stieltjesintegrator is a complex-valued function of bounded variation which represents the curvature and torsion, hence the conformation, of the backbone of an enzyme molecule. Theintegrand is a complex-valued continuous function which describes the shape of the surface of a substrate molecule. We postulate that enzyme-substrate interactions correspond to evaluations of Stieltjes integrals, and that observables of enzymic catalysis correspond to projections. Results from the mathematical theory of the Stieltjes integral are discussed together with their biological interpretations. We contrast the difference between structural and functional proteins, and construct analogues of enzyme cofactors, modifications, and regulation. Various techniques of locating the active site on enzymes are also given. We construct a total variation metric, which is particularly useful for detecting similarities among proteins. An examination on the many different modes of convergence of mathematical functions representing biological molecules leads to a mathematical statement of the fundamental dogma of molecular biology, that ‘structure implies function’. Similar arguments also result in the converse statement ‘function dictates structure’, which is a basic premise of relational biology. Stepped-helical approximations of the backbone space curves of enzymes provide a concrete computational tool with which to calculate the Stieltjes integrals that model enzymic catalysis, by replacing the integral with a finite series. The duality between enzymes and substrates (that they aremeters ‘observing’ one another) is shown to be a consequence of the mathematical duality of Banach spaces. The Stieltjes integrals of enzyme-substrate interactions are hence shown to be bounded bilinear functionals. The mechanism of enzymic catalysis, the transformation from substrate to product, is also formulated in the Stieltjes integration context via the mathematical theory of adjoints. The paper closes with suggestions for generalizations, prospects for future studies, and a review of the correspondence between mathematical and biological concepts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462069
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  • 59
    Digitale Medien
    Digitale Medien
    Genetic control theory of developmental events (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 785-825 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract An earlier theory of cell differentiation and morphogenesis (Wassermann, 1972, 1973, 1978) is combined with the genetic control model of Davidson and Britten (e.g. 1979). The resulting new theory suggests how, bysystematic process algorithms, specifically enumerated combinations of batteries of structural genes can become switched on in particularly enumerated cells, via battery-specific enumerable regulator genes. The systematization is idealized. Up to a certain stage of development in each mitotically arising cell a unique cell-specific combination of structural genes called ‘marker genes’ is active. Marker genes are assumed to code for cell-specifying marker proteins (CSMPs) which permit cells carrying related markers to recognize each other, thus permitting specific cell sorting.Batteries of marker genes could ensure great developmental precision and can safeguard—via redundancies of CSMP types—against accidental loss or detrimental mutational modification of CSMPs or marker genes, respectively. This paper is much concerned with cell lineage in relation to ‘microdifferentiation’, where ‘microdifferentiation’ of a cell refers to a cell's active marker genes and its syntheses of CSMPs. A drastic distinction is made between ‘microdifferentiation’ and ‘gross’ differentiation of a cell, where the same ‘gross’ differentiation may be shared by a large number of cells that could each be uniquely ‘microdifferentiated’. Typical ‘gross’ differentiation could manifest itself in tissue specificity, whereas, up to certain stages of development, all cells of the same gross differentiation type (say tissue specificity) could each be uniquely ‘microdifferentiated’. The theory also assumes that at certain stages of the developmental process some (or in some organisms all) of the previously uniquely specified cells could give rise to small (or occasionally large) clones of equispecified cells, some of which might form clusters that represent complete ‘morphogenetic fields’ Tentative implementation mechanisms are proposed which suggest how the theory could operate in molecular biological terms. In particular, CSMPs could endow cell surface membranes with a highly specific protein network, and an associated equally specific cell surface coat. It is suggested how these highly specified cell surface coats and other systems could provide an ‘extracellular guidance network’ which could help to direct cells to attain energetically optimal locations relative to each other based on the matching of their surface specificities. In numerous experimental situations, where normally present optimal matching of cells is excluded, ‘alternative matching’ based on experiment-specific suboptimal matching could explain many data, notably in experimental development neurobiology (Wassermann, 1978).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462071
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  • 60
    Digitale Medien
    Digitale Medien
    One-dimensional food chain equations and their generalization (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 859-868 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Two equations describing one-dimensional food chains are known to possess soliton solutions. It is demonstrated that both equations are embraced within another equation, which arises in the theory of chains of enzymic reactions. We find an elliptic function solution to this equation. We obtain a one-soliton solution from it and re-derive the elliptic function solutions of the two ecological equations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462074
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  • 61
    Digitale Medien
    Digitale Medien
    A simple solution of the non-stationary heat transport problem in capillarized biological tissue (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 879-889 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The temperature distribution in a perfused biological tissue is calculated for an instaneous point source. An approximate solution, which is simple enough to be evaluated by means of a hand calculator, is derived from the exact solution. It is expressed in terms of the deviation from an average temperature distribution. In an example, using realistic parameters for blood flow and thermal properties of tissue, the approximate solution differs at most 2% from the exact one.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462076
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  • 62
    Digitale Medien
    Digitale Medien
    Cannibalism in clumped populations (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 891-901 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A simple model for the introduction of a cannibalistic mutant into a noncannibalistic population (or vice versa) is developed for the case where the offspring of an adult are clumped. It is assumed that there is no difference between the cannibals and noncannibals except for eating habits. Conditions on the parameters specifying the population are derived such that noncannibalism is favored over cannibalism when these conditions are satisfied. Specifically, it is shown that noncannibalism is favored in a diffuse, highly clumped population if the probability of encountering one cannibal after another is greater than twice the probability of encountering a cannibal after encountering a noncannibal.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462077
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  • 63
    Digitale Medien
    Digitale Medien
    s-Consensus trees and indices (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 923-935 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract In the field of numerical taxonomy it is often desirable to determine a tree which is the consensus (common part) of severaln-trees, each of which represents a classification of the same set of objects. In this note, ans-consensus tree and corresponding consensus index for a collection ofn-trees are defined. The choice of a value for the parameters will determine the number of nodes in thes-consensus tree and its tendency to resemble the strict or Adams-consensus tree.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462079
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  • 64
    Digitale Medien
    Digitale Medien
    Qualitative study of a dynamical system for metrazol-induced paroxysmal depolarization shifts (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 903-922 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The convulsant pentylenetetrazol (PTZ) was used to trigger spike bursts and paroxysmal discharges inAplysia neurons. Voltage clamp experiments showed that PTZ induced a slow voltage-dependent potassium current and a persistent inward current. These currents are incorporated into a membrane model together with modified spike-generating Hodgkin-Huxley equations. From these data a metaphoric model is constructed and represented by a slow-fast dynamical system defined inR 4. With some values of the main physiological parameters, the system might have limit cycles for the fast dynamic. A qualitative study of the system shows that it satisfactorily reproduces the various observed patterns produced by PTZ.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462078
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  • 65
    Digitale Medien
    Digitale Medien
    A note on the evaluation of similarity (homology) of short sequences with long sequences (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 951-961 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Monte Carlo data on the comparison of a short sequence with a long one are developed in a manner to quantify the occurrence of gaps.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462081
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  • 66
    Digitale Medien
    Digitale Medien
    Blood flow subject to a single cycle of body acceleration (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 937-949 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The present study deals with the effect of a single cycle of body accelerations on blood flow in arteries. Such body accelerations are usually caused unintentionally, for example during travel in road vehicles, aircraft or spacecraft. A mathematical model of flow in single arteries subject to a pulsating pressure gradient due to the normal heart action as well as body acceleration expressible in terms of unit functions is presented. The body acceleration is such that it builds up from zero to a maximum value at a uniform rate, remains constant at the maximum value for some time, and thereafter reduces to zero at a uniform rate. The resulting equations are solved by using the technique of Laplace transforms. Computational results are presented for the effects of body accelerations on flow variables namely flow rate, velocity of flow, acceleration and shear stress corresponding to blood flow in the human aorta.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462080
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  • 67
    Digitale Medien
    Digitale Medien
    Characterizing conditions for generalized Verhulst logistic growth of a biological population (1984)
    Springer
    Bulletin of mathematical biology 46 (1984), S. 963-965 
    Details
    ISSN: 1522-9602
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract It is shown that a biological population or subpopulation composed ofN individuals can be governed by a generalized Verhulst logistic equation with time-dependent rate functions if and only if certain characterizing conditions are satisfied by ∂N/∂N 0 whereN 0 is the value ofN att=0.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02462082
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  • 68
    Digitale Medien
    Digitale Medien
    Energiewechsel bei Nüchterung und anschließender Realimentation (1984)
    Springer
    European journal of nutrition 23 (1984), S. 12-19 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Energie ; Wärmeproduktion ; Realimentation ; Nüchternumsatz ; Erhaltungsumsatz
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Summary A metabolism trial with six adult sows was conducted to study the effect of fasting and realimentation on heat production, energy retention, and utilization of energy. Complete balance measurements by indirect calorimetry (CN-method, RQ-method) were carried out from the 8th to the 10th day of fasting, and thereafter from the 1st to the 7th day and from the 33rd to the 36th day of the realimentation phase. Previous to fasting and during the time of refeeding the energy supply was adapted to maintenance requirement. Heat production rose by 20% after refeeding the animals. This heat increment corresponded to 2.2 MJ/kg feed dry matter, or 12% of the energy intake, respectively. The stimulation of heat production induced by refeeding occurred spontaneously within one day. After the first day of refeeding a plateau was reached, which in the course of the steady energy supply was still present even after the 5th week of realimentation. Residual effects of fasting in the mode of a compensatory heat production were not observed. Therefore, a constant utilization of efficiency of metabolizable energy for maintenance was estimanted at 82%. The change of body energy during the entire experimental period resulted in a loss of 198 MJ corresponding to about 5% of the body weight.
    Notizen: Zusammenfassung In einem Gesamtstoffwechselversuch mit 6 ausgewachsenen Sauen wurden Wärmeproduktion und Energieretention bei Nüchterung und nachfolgender kontrollierter Realimentation untersucht. Die quantitative Stoffwechselmessung mit Hilfe der indirekten Kalorimetrie (CN-Methode und RQ-Methode) fand am 8.–10. Hungertag und am 1.–7. sowie 33.–36. Tag der Wiederfütterung statt. Die Nahrungszufuhr war vor und nach der Hungerphase auf den energetischen Erhaltungsbedarf ausgerichtet. Die Wärmeproduktion lag in der Realimentation gegenüber der Hungerphase um 20% höher. Dieser Wärmezuwachs entsprach 2,2 MJ/kg Futtertrockenmasse bzw. 12% der Energieaufnahme. Der Energiewechsel adaptierte sich innerhalb eines Tages an die Situation der Wiederfütterung. Danach blieb die Wärmebildung bzw. die Energieretention bis Ende des Versuchs auf einem konstanten Niveau. Nachwirkungen der Nüchterung im Sinne einer kompensatorisch veränderten Wärmeproduktion traten nicht auf. Die energetische Verwertung der umsetzbaren Energie für Erhaltung berechnete sich auf 82%. Die über die gesamte Versuchszeit erstellte Energiebilanz ergab ein Defizit der Körperenergie von 198 MJ, entsprechend etwa 5% des Körpergewichtes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02020892
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  • 69
    Digitale Medien
    Digitale Medien
    Der Einfluß von Guarmehl auf die endogene Stickstoffausscheidung bei Ratten, bestimmt mit Hilfe der15N-Tracer-Technik (1984)
    Springer
    European journal of nutrition 23 (1984), S. 31-40 
    Details
    ISSN: 1436-6215
    Schlagwort(e): endogener Kotstickstoff ; bakterieller Stickstoff ; Guarmehl ; 15N-Tracer-Technik ; Ratten
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Summary The metabolic fecal nitrogen was determined in 8 young rats (90–100 g body weight) using a single oral dose of 75 mg15N-glycine. Four rats were fed a diet containing 8 % guar and 4 rats received a control diet without guar. Compared to the control group, apparent protein digestibility and nitrogen balance were significantly lower in the guar group. After an initial steep rise the15N-elimination in feces and urine (days 2–8 after15N-glycine application) followed an exponential curve in at least 2 phases, with increasing half-time values. The proportion of metabolic fecal nitrogen to total fecal nitrogen was calculated from the15N-atom-% excess, determined daily in urine and in feces. This calculation is based on the assumption that the specific15N-activity (15N-atom-% excess) in urine represents the specific15N-activity of the endogenous nitrogen pool. The addition of guar raised the proportion of metabolic fecal nitrogen from 51 % (control) to 73 %, corresponding to an increase in total fecal nitrogen loss (24 mg) observed in the guar-fed animals. This indicates that the rise in fecal nitrogen loss caused by guar is due almost entirely to enhanced secretion of endogenous nitrogen and not to undigested food protein. Based on the analysis of 2,6-diamino-pimelic acid in the feces of 4 rats the proportion of bacterial nitrogen in the feces was calculated. It amounted to 19.8 % of total fecal N in the control group, and to 30.1 % in the guar group, or to 39.4 % and 44.4 % of metabolic fecal nitrogen respectively. Obviously the increased dietary fiber intake also caused a rise in the amount of metabolic fecal nitrogen, which is derived from gastro-intestinal secretions and epithelial tissue.
    Notizen: Zusammenfassung Zur Bestimmung der endogenen Stickstoffausscheidung im Kot wurde acht jungen Ratten (90 bis 100 g Körpergewicht) eine orale Dosis von 75 mg15N-Glycin verabreicht. Vier Ratten erhielten eine 8%ige Guarmehldiät und vier Ratten eine Kontrolldiät ohne Guarmehlzusatz. Gegenüber der Kontrollgruppe wurde eine signifikante Verringerung der scheinbaren Proteinverdaulichkeit und der N-Bilanz in der Guarmehlgruppe festgestellt. Nach einem anfänglichen steilen Anstieg verlief die15N-Elimination in Kot und Urin vom 2. bis 8. Tag nach der15N-Glycin-Applikation exponentiell in mindestens zwei Phasen mit steigender Halbwertszeit. Aus den experimentell ermittelten Tageswerten des15N-Atom-%-Überschusses in Urin und Kot wurde der Anteil des endogenen Stickstoffs im gesamten Kotstickstoff berechnet. Hierbei wurde vorausgesetzt, daß die spezifische15N-Aktivität des Urins (15N-Atom-%-Überschuß) dem15N-Markierungsgrad des endogenen Stickstoff-Pools entspricht. Durch Guarmehlzusatz erhöhte sich der Anteil des endogenen Kotstickstoffs von 51% (Kontrollgruppe) auf 73%, was einem Anstieg von 10 mg N/Tag auf 32 mg N/Tag entspricht. Diese Differenz von 22 mg N/Tag ist vergleichbar mit dem um 24 mg/Tag erhöhten N-Verlust im Kot der Tiere in der Guarmehlgruppe. Demnach sind die durch Guarmehl verursachten erhöhten N-Verluste fast ausschließlich durch eine vermehrte endogene N-Sekretion und nicht durch unverdautes Nahrungsprotein bedingt. Mit Hilfe der 2,6-Diamino-pimelinsäure-Analyse des Kots von vier Ratten wurde der Anteil des aus Darmbakterien stammenden Kot-N bestimmt. Er betrug 19,8 % (Kontrollgruppe) bzw. 30,1% (Guarmehlgruppe) des Gesamt-Kot-N bzw. 39,4% (Kontrollgruppe) und 44,4 % (Guarmehlgruppe) des endogenen Kot-N. Hieraus ist zu folgern, daß die erhöhte Ballaststoffzufuhr auch eine vermehrte Ausscheidung an endogenem Stickstoff in Form von N-haltigen Sekreten und Epithelzellen des Magen-Darm-Traktes bewirkt hat.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02020894
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  • 70
    Digitale Medien
    Digitale Medien
    Der Einfluß von Feststoffsubstraten auf Kolonienbildung von Mikroorganismen (1984)
    Springer
    European journal of nutrition 23 (1984), S. 58-65 
    Details
    ISSN: 1436-6215
    Schlagwort(e): Feststoffsubstrate ; Kolonienbildung von Mikroorganismen
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Bacteria have been found to grow differently at contact sites to both organic and anorganic solids as on pure agar media. Of 16 ad hoc selected bacterial strains, the following species (arranged in decreasing order) responded with stronger colony formation: Bacillus subtilis, B. cereus, Streptococcus sanguis, S. saprophyticus, S. faecalis, Escherichia coli, Micrococcus flavus, Actinomyces viscosus, Veillonella sp., Enterobacter liquefaciens, Yersinia enterocolitica. Lactobacillus casei behaved neutral. Proteus vulgaris, Y. enterocolitica and Chromobacterium violaceum grow on certain media only in the presence of solid particles. The yeasts Endomyces lactis, Saccharomyces cerevisiae, Rhodotorula mucilaginosa and Cryptococcus nigricans did not respond to solid particles during colony formation. The kind of protein — animal (meat) or vegetable (soy beans) — did not influence the behaviour of the microorganisms in these experiments.
    Notizen: Zusammenfassung Es wurde festgestellt, daß die Bakterien an Kontaktstellen mit sowohl organischen als auch anorganischen Feststoffmaterialien anders wachsen als auf reinen Agarnährböden. Von 16 ad hoc gewählten Bakterienstämmen reagierten folgende Spezies mit intensiverer Kolonienbildung in sinkender Reihenfolge: Bacillus subtilis, B. cereus, Streptococcus sanguis, S. saprophyticus, S. faecalis, Escherichia coli, Micrococcus flavus, Actinomyces viscosus, Veillonella sp., Enterobacter liquefaciens, Yersinia enterocolitica. Lactobacillus casei verhielt sich neutral. Proteus vulgaris, Y. enterocolitica und Chromobacterium violaceum wachsen auf bestimmten Nährböden nur in Anwesenheit der Festpartikel. Die Hefen Endomyces lactis, Saccharomyces cerevisiae, Rhodotorula mucilaginosa und Cryptococcus nigricans zeigten bei der Kolonienbildung keine Reaktion auf die Feststoffpartikel. Die Art des Proteins in Nährböden — tierisch (Fleisch) oder pflanzlich (Sojabohnen) — beeinflußte das Verhalten der Mikroorganismen in diesen Untersuchungen nicht.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02020897
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  • 71
    Digitale Medien
    Digitale Medien
    Vitamin A und Hörorgan Literaturübersicht (1984)
    Springer
    European journal of nutrition 23 (1984), S. 104-112 
    Details
    ISSN: 1436-6215
    Schlagwort(e): vitamin A ; inner ear ; review ; vitamin A deficiency ; hearing loss
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Since the first characterization and description of vitamin A this is used in otolaryngologic therapy for different forms of hearing disorders, and its relation to the inner ear is subject of investigation. Animal experiments and clinical studies were done to clarify the significance of vitamin A for the function of hearing. Besides this there were a lot of observations describing correlations between vitamin A metabolism and hearing loss. Recent investigations showed that vitamin A is present in high concentrations in the inner ear and stored there. Morphological experiments revealed different and in some way contradictory results, but they showed that vitamin A seems to be essential for inner-ear morphogenesis.
    Notizen: Zusammenfassung Seit der Entdeckung des Vitamin A und ersten Beschreibung seiner Wirkung wird dieses auch in der Otorhinolaryngologie als Therapeutikum bei den unterschiedlichsten Formen von Hörstörungen eingesetzt und seine Wirkungsweise am Innenohr erforscht. So wurden sowohl tierexperimentelle als auch klinische Studien durchgeführt, um die Bedeutung des Vitamins für die Funktion des Hörorgans zu klären. Daneben wurden eine Reihe von Beobachtungen mitgeteilt, die einen Zusammenhang zwischen Störungen des Vitamin-A-Stoffwechsels und gleichzeitig auftretenden Hörstörungen beschrieben. Neuere Untersuchungen haben ergeben, daß Vitamin A in hohen Konzentrationen im Innenohr vorkommt und dort auch gespeichert werden kann. Morphologische Untersuchungen führten zu den unterschiedlichsten Ergebnissen und haben gezeigt, daß Vitamin A für die Morphogenese des Innenohres von Bedeutung zu sein scheint.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02021685
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  • 72
    Digitale Medien
    Digitale Medien
    Effects of various oils and of starvation on the lipid metabolism in brain (1984)
    Springer
    European journal of nutrition 23 (1984), S. 276-282 
    Details
    ISSN: 1436-6215
    Schlagwort(e): starvation ; brain ; lipid metabolism ; dietary lipids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Der Einfluß verschiedener Nahrungsfette auf den Lipidstoffwechsel des Gehirns während Hunger wurde untersucht. Albinoratten wurden 8 Tage lang mit Dalda, Senföl oder Erdnußöl gefüttert. Einige Tiere blieben anschließend 3 und 5 Tage lang ohne Nahrung. Die Gesamtlipide und die Galaktolipide wurden durch Nahrungsfette und durch Hunger nicht beeinflußt, während die Phospholipide unabhängig von der Art des Nahrungsfetts signifikant zunahmen. Cholesterin nahm in den mit Dalda und mit Erdnußöl gefütterten Gruppen zu und nahm ab während des Hungerns. In der Hungerperiode im Anschluß an die Fettzufuhr war der Einbau von 1-14C-Acetat in Lipide von Gehirnschnitten nach Erdnußöl höher als nach Dalda. Nach Senföl war der Einbau nur gering.
    Notizen: Summary In this study the effects of the dietary fat sources, viz., Dalda, mustard oil and groundnut oil in the brain lipid metabolism during starvation has been investigated. To find out this, these oils were fed to albino rats for 8 weeks followed by 3 and 5 days of starvation. Total as well as galactolipids of brain were not affected by dietary oils and starvation, whereas phospholipids of brain were significantly increased by fasting irrespective of the dietary fats. On the other hand, cholesterol was found to be increased in the groups fed with Dalda and groundnut oil and to be significantly decreased during fasting experiments. Incorporation of (1-14C)acetate into lipid of the brain slices of rats fed different experimental diets than followed by starvation revealed that the uptake of radioactivity was higher in the group fed with groundnut oil, followed by Dalda. Low uptake was observed in the group fed with mustard oil.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02020640
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  • 73
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 22-22 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721247
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  • 74
    Digitale Medien
    Digitale Medien
    Tourenplanung für zwei Depots bei offenen Touren (1984)
    Springer
    OR spectrum 6 (1984), S. 39-46 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary Several methods for solving open-tour-problems with two depots are presented. The solution is based on modified methods for solving travelling salesman- and vehicle dispatching problems. Further, an essentially new method based on savings is developed and the results of detailed tests are presented. The tests allow us general statements as to which method is more efficient for solving a well defined problem in accordance to its structure.
    Notizen: Zusammenfassung Es werden mehrere verschiedene Lösungsverfahren für das Offene-Tour-Probelm mit zwei Depots vorgestellt. Dabei handelt es sich um modifizierte Verfahren zur Lösung von Travelling Salesman- und Tourenplanungsproblemen. Darüberhinaus wird ein in wesentlichen Punkten neues Verfahren erarbeitet. Ausführliche Testrechnungen geben Aufschluß über die Effizienz der vorgestellten Verfahren und lassen tendenzielle Aussagen darüber zu, welchem Verfahren bei Vorliegen einer bestimmten Problemstruktur der Vorzug zu geben ist.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721250
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  • 75
    Digitale Medien
    Digitale Medien
    Tagungen (1984)
    Springer
    OR spectrum 6 (1984), S. 59-59 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721255
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  • 76
    Digitale Medien
    Digitale Medien
    mbp-Seminare in Zusammenarbeit mit der DGOR 1984 (1984)
    Springer
    OR spectrum 6 (1984), S. 59-60 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721256
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  • 77
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 84-84 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721081
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  • 78
    Digitale Medien
    Digitale Medien
    Analyse qualitativer Daten: Einführung und Übersicht (1984)
    Springer
    OR spectrum 6 (1984), S. 67-83 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary Over the last 10 years we observe an enormous progress in Qualitative Data Analysis. While in France especially the methods dealing with nominal data have been advanced, in Germany more complex types of data have been treated. New developments show that the analysis of appropriate binary relations onN orN ×N is possible for problems of a greater size. The problem of computing a partition or a hierarchy can be formulated as a binary linear optimization problem or an optimization problem on appropriate lattices of relations. The problems of representation and reproduction are reduced to the multidimensional scaling concept. For each type of data we consider all compatible scales and give the corresponding optimization problems, based on the classical principle of least squares.
    Notizen: Zusammenfassung Die Analyse qualitativer Daten hat in den vergangenen 10 Jahren einen enormen Aufschwung genommen. Während zunächst vor allem in Frankreich die Auswertung nominaler Daten forciert wurde, hat man sich in der Bundesrepublik Deutschland auch mit der Auswertung komplexerer Datenstrukturen beschäftigt. Neuere Trends belegen nachdrücklich, daß die Auswertung strukturadäquater Relationen aufN bzw.N ×N zum Teil auch für umfangreichere Probleme möglich ist. Das Problem der disjunkten bzw. hierarchischen Klassifikation führt oft zu Aufgaben der binären linearen Optimierung oder zu Optimierungsansätzen auf geeigneten Verbänden von Relationen. Das Problem der Repräsentation und Identifikation mit qualitativen Daten wird auf das Konzept der mehrdimensionalen Skalierung zurückgeführt. Man läßt für jeden Merkmalstyp alle mit der Struktur verträglichen Skalierungen zu und formuliert Optimierungsprobleme, die auf dem klassischen Prinzip der kleinsten Quadrate beruhen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721080
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  • 79
    Digitale Medien
    Digitale Medien
    A generalization of an oddness-theorem for bimatrix games (1984)
    Springer
    OR spectrum 6 (1984), S. 217-222 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Ein bekanntes Resultat von Lemke und Howson besagt, daß die Anzahl der Nash-Gleichgewichtungspunkte für nichtdegenerierte Bimatrix-Spiele ungerade ist. Dieses Ergebnis wird im folgenden Sinne verallgemeinert: es wird nachgewiesen, daß die Anzahl der nichtdegenerierten Gleichgewichtspunkte für Spiele mit höchstens endlich vielen Gleichgewichtspunkten stets ungerade ist. Daraus ergibt sich, daß eindeutige Gleichgewichtspunkte nichtdegeneriert sind. Außerdem erhält man damit erneut einige auf Jansen zurückgehende Resultate.
    Notizen: Summary It is a well-known result of Lemke and Howson that the number of Nash-equilibria of a bimatrix game is odd in a nondegenerate case. In this paper a generalized version of this theorem will be proved. It will be shown that in case of finiteness of the number of Nash-equilibria the number of nondegenerate Nash-equilibria is always odd. Consequences of this fact are nondegeneracy for unique Nash-equilibria and some results of Jansen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720071
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  • 80
    Digitale Medien
    Digitale Medien
    Isotone policies for the value iteration method for Markov decision processes (1984)
    Springer
    OR spectrum 6 (1984), S. 223-227 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Wir betrachten die Wertiteration bei diskontierten Markovschen Entscheidungsprozessen mit abzählbarem Zustandsraum. Wir zeigen, daß unter gewissen Bedingungen eineN-isotone Folge von optimalen Entscheidungsregeln und Wertfunktionen existiert.N-isoton heißt eine Folge von Entscheidungsregeln {δ n },n ∈ {1,2,...}=N, dann, wenn für eine Halbordnung ≲ überK=UK(i) gilt δ n−1 (i) δ n−1(i)≲δ n (i) für allen⩾2 undi ∈I. (K(i is die Menge der zulässigen Aktionen im Zustandi). Eine analoge Definition derN-Isotonie gilt für die Wertfunktionen {vn},n⩾1.
    Notizen: Summary This paper considers the value iteration process for countable state discounted Markov decision processes and shows that under certain conditions there will exist anN-isotone sequence of optimal decision rules and value functions, whereN-isotonicity of a sequence of decision rules {δ n }, n ∈ {1,2,...}=N requires that, for a specified partial order ≲ overK=UK(i) (K(i) being the feasible action space fori) then δ n−1(i)≲δ n (i), ∀n⩾2 and alli ∈I, with a similar definition ofN-isotonic for the value functions {v n },n⩾1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720072
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  • 81
    Digitale Medien
    Digitale Medien
    Call for papers (1984)
    Springer
    OR spectrum 6 (1984), S. 250-250 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720077
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  • 82
    Digitale Medien
    Digitale Medien
    Dank den Referenten (1984)
    Springer
    OR spectrum 6 (1984), S. 251-251 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720078
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  • 83
    Digitale Medien
    Digitale Medien
    Eingegangene Bücher (1984)
    Springer
    OR spectrum 6 (1984), S. 253-253 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720081
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  • 84
    Digitale Medien
    Digitale Medien
    Recent trends in combinatorial optimization (1984)
    Springer
    OR spectrum 6 (1984), S. 1-21 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Wir geben einen Überblick über wichtige Teilbereiche der kombinatorischen Optimierung, so wie sie sich heute darstellen. Der Schwerpunkt liegt auf neueren theoretischen Ergebnissen, die sich für Anwendungen in der Praxis als nützlich erwiesen haben. Abschnitt 2 dient der Vorstellung einzelner Beispiele und der Erläuterung unserer Bezeichnungsweise. Zentrale Begriffe aus der Komplexitätstheorie wie etwa die eines einfachen oder schwierigen Problems sind Gegenstand von Abschnitt 3. Ausgehend von Matroid-, Matching- und Netzwerkflußproblemen beschreiben wir anschlie-ßend, auf welche Weise polynomial lösbare Verallgemeinerungen dieser Probleme erhalten und in eine allgemeine Theorie submodularer Funktionen eingeordnet werden können. Im ersten Teil eines Abschnittes über Polyedertheorie besprechen wir orientierte Matroide, mit deren Hilfe die Theorie der konvexen Polyeder in einem rein kombinatorischen Rahmen verallgemeinert werden kann. Der 2. Teil befaßt sich mit Beziehungen zwischen linearen Systemen und Kombinatorik, hier besonders mit ganzzahligen Polyedern. Struktur und Bewertung von heuristischen Verfahren sind Gegenstand von Abschnitt 6. Schließlich beschreiben wir Ansätze zur Lösung schwieriger Optimierungsprobleme, die sich bei der Anwendung auf spezielle Problemklassen als leistungsfähig erwiesen haben.
    Notizen: Summary We survey important parts of the theory of combinatorial optimization as it is developed today. The emphasis lies on new theoretical results, which have proven useful in practical applications. In Sect. 2 we present some examples and explain our basic notation. The purpose of Sect. 3 is to introduce central concepts of complexity theory, in particular the notions of easy and hard problems. Starting from matroid, matching and network flow problems we describe how polynomially solvable generalizations of these can be obtained, taking account of the theory of submodular functions as a general framework. Oriented matroids as a suitable concept by which to generalize the theory of convex polyhedra in a purely combinatorial setting are discussed in the first part of a section on polyhedral theory. Part 2 is concerned with the relations between linear systems and combinatorics, in particular integer polyhedra. The structure and evaluation of heuristic algorithms is the subject of Sect. 6. Finally, we describe basic ideas for the solution of hard optimization problems as they have proven efficient for particular problem classes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721246
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  • 85
    Digitale Medien
    Digitale Medien
    Optimal replacement policy for a redundant system (1984)
    Springer
    OR spectrum 6 (1984), S. 47-51 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Wir untersuchen die Zuverlässigkeit eines Seriensystems ausn Komponenten, bei dem für diei-te Komponentem i − 1 Reserveelemente zur Verfügung stehen. Mit Hilfe der dynamischen Optimierung bestimmen wir die optimale Ersetzungspolitik. Besteht das System aus identischen Paaren, hängt die Entscheidung von der Zahl der intakten Paare ab. Für diesen Fall geben wir beispielhaft einige numerische Ergebnisse.
    Notizen: Summary This paper considers the reliability of a system which consists ofn components connected in series, the ithcomponent being supported by (m i − 1) units in parallel and obtains the optimal policy of replacement by dynamic programming. In the case of a system consisting of identical pairs, the decision depends on the number of operable pairs. For this case sample calculations are presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721251
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  • 86
    Digitale Medien
    Digitale Medien
    DGOR-Jahrestagung 1984 (1984)
    Springer
    OR spectrum 6 (1984), S. 58-58 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721254
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  • 87
    Digitale Medien
    Digitale Medien
    Eingegangene Bücher (1984)
    Springer
    OR spectrum 6 (1984), S. 60-60 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721257
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  • 88
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 92-92 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721083
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  • 89
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 108-108 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721085
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  • 90
    Digitale Medien
    Digitale Medien
    On tests of the arbitrage pricing theory (1984)
    Springer
    OR spectrum 6 (1984), S. 109-117 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung In der von Ross entwickelten Arbitragebewertungstheorie werden die Wertpapierrenditen von gemeinsamen und individuellen Faktoren erzeugt, die vorab nicht spezifiziert werden. Es wird gezeigt, daß eine exakte Arbitragebewertung bei endlich vielen Wertpapieren genau dann besteht, wenn ein bestimmtes (μ,σ)-effizientes Portefeuille ohne unsystematisches Risiko existiert. Dies ist die wesentliche testbare Implikation der Arbitragebewertungstheorie. Außerdem wird gezeigt, daß Tests, soweit sie die Hauptkomponentenmethode oder die Faktorenanalyse verwenden, einen erheblichen Bias gegen die Theorie aufweisen.
    Notizen: Summary In the arbitrage pricing theory, developed by Ross, asset returns are generated by common and residual factors which are not prespecified. This paper shows that exact arbitrage pricing exists in a finite economy if and only if a specific mean-variance efficient portfolio with zero residual variance exists. Zero residual variance is the essential testable implication of the arbitrage pricing theory. Moreover, it is shown that tests of this theory using either principal component analysis or factor analysis to extract factors appear to be strongly biased against the theory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721086
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  • 91
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 124-124 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721089
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  • 92
    Digitale Medien
    Digitale Medien
    Tagungen (1984)
    Springer
    OR spectrum 6 (1984), S. 131-131 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721091
    Standort Signatur Erwartet Verfügbarkeit
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  • 93
    Digitale Medien
    Digitale Medien
    Eingegangene Bücher (1984)
    Springer
    OR spectrum 6 (1984), S. 132-132 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01721093
    Standort Signatur Erwartet Verfügbarkeit
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  • 94
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 166-166 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01719614
    Standort Signatur Erwartet Verfügbarkeit
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  • 95
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 186-186 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01719617
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    Digitale Medien
    Digitale Medien
    Zur spieltheoretischen Ableitung strategischer Unternehmensentscheidungen aus einem Wettbewerbsmodell (1984)
    Springer
    OR spectrum 6 (1984), S. 177-185 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Summary Rational strategic decisions are based on the knowledge how the strategic variables of the firm are related to the goal variable. The goal achievement is not only influenced by the strategies of the firm but also by the strategies of the competitors. Therefore we propose in this article a competition model, in which competition behaviour is explicitly defined. The optimum solution is interpreted economically.
    Notizen: Zusammenfassung Rationales strategisches Handeln setzt voraus, daß die Wirkungen der strategischen Variablen auf die Zielgröße des Unternehmens bekannt sind. Der Zielerreichungsgrad wird aber nicht nur von den unternehmensbezogenen Strategien, sondern auch vom Konkurrenzverhalten beeinflußt. Daher wird in der vorliegenden Abhandlung ein Wettbewerbsmodell, das Konkurrenzverhalten explizit einbezieht, entwickelt und die Optimallösung ökonomisch interpretiert.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01719616
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    Digitale Medien
    Digitale Medien
    mbp-Seminare in Zusammenarbeit mit der DGOR 1984 (1984)
    Springer
    OR spectrum 6 (1984), S. 192-192 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01719620
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 206-206 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720069
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    A comparison of techniques for solving the fleet size and mix vehicle routing problem (1984)
    Springer
    OR spectrum 6 (1984), S. 207-216 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Das Problem der Bestimmung einer optimalen Anzahl von möglicherweise verschiedenen Fahrzeugen in einem Fuhrpark sowie die bestmögliche Zusammensetzung verschiedener Fahrzeuge bei der Tourenplanung, wobei die Fixkosten der Beschaffung und die Kosten für die laufende Unterhaltung der Routen minimiert werden soll, wird diskutiert. Einige bekannte Heuristiken und ein Algorithmus zur Bestimmung einer unteren Schranke werden besprochen. Mit diesen Grundlagen wird eine neue Heuristik vorgeschlagen. Um die Leistungsfähigkeit der verschiedenen Lösungsmethoden zu vergleichen, werden anschließend Rechenergebnisse verschiedener benchmark Probleme vorgestellt.
    Notizen: Summary In the fleet size and mix vehicle routing problem, one decides upon the composition and size of a possibly heterogeneous fleet of vehicles so as to minimize the sum of fixed vehicle acquisition costs and routing costs for customer deliveries. This paper reviews some existing heuristics for this problem as well as a lower bound procedure. Based on the latter, a new heuristic is presented. Computational results are provided for a number of benchmark problems in order to compare the performance of the different solution methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720070
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Buchbesprechungen (1984)
    Springer
    OR spectrum 6 (1984), S. 238-238 
    Details
    ISSN: 1436-6304
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Wirtschaftswissenschaften
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01720075
    Standort Signatur Erwartet Verfügbarkeit
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