bluuebunny/crossref_metadata_2025 huggingface dataset:
Evoluationary Consequences of Density Dependence on Optimal Maturity in Animals with Indeterminate Growth
Authors: Heino Mikko , Kaitala Veijo
Published: October 2003

We consider life history consequences of density dependence to age at maturity in populations of freshwater clams. We study in particular the trade-off between growth and reproduction. For the purposes of the analysis we developed an age-structured population dynamics model for animals with indeterminate growth. In modelling evolution, we apply the concept of evolutionarily stable strategies (ESS) and compare them to the traditional density independent optimization criteria, or fitness measures, r and R0. Population regulation by density substantially affects the optimal timing of maturity. Different types of density dependence may produce both quantitatively and qualitatively different predictions for ESS age at maturity. We conclude that the way in which density dependence works in populations is essential for analysing life history evolution and population dynamics. As a whole, density dependence should be considered as an important evolutionary force, affecting the key fitness components like death and birth rates either directly, or indirectly via changes in e.g. growth rate.
Delayed Maturity and Reproductive Gaps in Fluctuating Populations
Authors: Kaitala Veijo
Published: October 2003

The evolutionary stability of delayed maturity and suppressed breeding, including a possibility of reproductive gaps, in an age-structured population breeding more than once within a breeding season was studied. In this study I show that breeding strategies may depend strongly on intra-specific competition (population density), in which case the breeding strategies will also modify the overall growth rates of the population. Consequently, breeding strategies may fluctuate from year to year when the individuals adjust their breeding behaviors according to chaotically varying population densities.
Information Macro Dynamic Approach for Modelling in Biology and Medicine
Authors: Lerner Vladimir S.
Published: October 2003

Informational Macro Dynamics (IMD) contains formal mathematical and computer methodology to describe transformation of random information processes (at microlevel) into system dynamic processes (at macrolevel) to model the observed processes on the basis of both discovery of their information dynamic regularities, and the identification of macro dynamic equations.

Informational description of interactions includes not only physical connections between the processes, but also the information superimposition of processes of different nature with transferring information from one interacting process to others and creating the information defect. The synthesized optimal macro dynamics gives rise to self-organized structures, becoming ordered in the process of optimal motion.

The macro model's systemic mechanisms have similarities with the biosystemic functional activities. This paper introduces the concrete biological examples of the constructive IMD model applications for analysis and discovery of some important biosystem mechanisms, functions and phenomena.
Adaptive Dynamics in a 2-Patch Environment: A Toy Model for Allopatric and Parapatric Speciation
Authors: Meszéna Géza , Czibula István , Geritz Stefan
Published: October 2003

Adaptation to an environment consisting of two patches (each with different optimal strategy) is investigated. The patches have independent density regulation ('soft selection'). If the patches are similar enough and migration between them is strong, then evolution ends up with a generalist ESS. If either the difference between the patches increases or migration weakens, then the generalist strategy represents a branching singularity: The initially monomorphic population first evolves towards the generalist strategy, there it undergoes branching, and finally two specialist strategies form an evolutionarily stable coalition. Further increasing the between-patch difference or decreasing migration causes the generalist to lose its convergence stability as well, and an initially monomorphic population evolves towards one of the specialists optimally adapted to one of the two patches. Bifurcation pattern of the singularities is presented as a function of patch difference and migration rate.

Connection to speciation theory is discussed. The transition from the generalist ESS to the coexisting pair of specialist strategies is regarded as a clonal prototype of parapatric (if the between-patch difference increases) or allopatric (if the migration decreases) speciation. We conclude that the geographic and the competitive speciation modes are not distinct classes.
Nonlinear Oscillations of the Yates-Pardee-Goodwin Metabolic Pathway with Coupling — The Role of Exterior Pools
Authors: Morillon J.-P. , Doubabi S. , Costalat R.
Published: October 2003

An analytic method referred to as the harmonic balancing technique has been applied in order to study the effect of diffusion between compartments (coupling between pools) on the Yates-Pardee-Goodwin metabolic pathway. The behaviour of the pathway is modelled on a set of coupled ordinary nonlinear differential equations. This set is transformed into a single feedback control loop with a nonlinear function and a linear filter. It is shown that coupling modifies the linear filter such that the frequency and the amplitude of the oscillations decrease. Further results are then obtained by numerical studies, and compared with the analytical approach and previous stability analysis of metabolic pathways.
A Model of Motivation with Chaotic Neuronal Dynamics
Authors: Tsitolovsky Lev E.
Published: October 2003

The key problem to creating an autonomous system is: how does the brain choose its reactions, and how are motivation determined by ongoing signals, memory and heredity. In attempts to design a robot brain, several efforts have been made to design a self-contained control system that mimics biological motivation. However, it is impossible to develop an artificial brain using conventional computer algorithms, since a conventional program cannot predict all of the possible perturbations and disturbances in the environment, and hence cannot plan strategies that allow the system to overcome these perturbations and return to an optimal state. An external programmer must constantly update the system about the proper strategies needed to overcome newly-encountered perturbations. In contradistinction, living systems demonstrate excellent goal-directed behavior without the participation of an external programmer, and without full knowledge of the external environment. Biological motivation refers to actions on the part of an organism that lead to the attainment of a specific goal. When the organism attains the goal it is in an optimal state, and no further actions are generated. A deviation from the optimum will result in a change in activity that leads to a return to the optimum. Biologic motivations arise as the result of metabolic disturbances and are related to transient injury of the specific neurons. Treatments which protect neurons satisfy motivations and exert a psychotropic action relative to relief. I have developed a novel hypothesis of how living systems achieve a goal, based on data gathered on the effects of motivation on individual neurons. I claim that if the neuron affects the non-stability of its postsynaptic targets (probably by means of motivationally-relevant substances) in the end it chooses its reaction, although at each instant it acts by chance.
The Many Facets of Evolutionary Dynamics
Authors: Diekmann Odo
Published: October 2003

In this note we present an outsider's view on the mathematical description of long term biological evolution as driven by natural selection. It is an outlook to the future, more than an account of what has been achieved so far.
A Simple Model for the Evolution of Evolution
Authors: Fussy Siegfried , Grössing Gerhard , Schwabl Herbert
Published: October 2003

A simple model of macroevolution is proposed exhibiting both the property of punctuated equilibrium and the dynamics of potentialities for different species to evolve towards increasingly higher complexity. It is based on the phenomenon of fractal evolution which has been shown to constitute a fundamental property of nonlinear discretized systems with one memory- or random-based feedback loop. The latter involves a basic "cognitive" function of each species given by the power of distinction of states within some predefined resolution. The introduction of a realistic background noise limiting the range of the feedback operation yields a pattern signature in fitness space with a distribution of temporal boost/mutation distances according to a randomized devil's staircase function.

Introducing a further level in the hierarchy of the system's rules, the possibility of an adaptive evolutionary change of the resolution itself is implemented, thereby providing a time-dependent measure of the species' cognitive abilities: an additional feedback loop makes use of the inevitable intrinsic fluctuations within the fitness landscape to direct the temporal change of the resolution. Feeding back the small adaptive changes of resolution into the essentially directionless variations of the patterns' lifetimes in fitness space effectively leads to a clear tendency towards increasing evolution potentials for each species ("hierarchically emergent fractal evolution").
Extinction Waves in Spatial Population Dynamic Models — the Case of two Sibling Bird Species H. Icterina and H. Polygotta
Authors: Gourbiere Sébastien , Auger Pierre , Chassé Jean Luc , Faivre Bruno
Published: October 2003

Two spatial models of populations dynamics are presented to study the evolution of spatial distributions of two sibling species. We defined firstly an interspecific competition model and secondly a one predator-two preys model. They are constituted of a two dimensional discrete set of cells.Initially, the two competing or prey species occupy two complementary areas with common zone and the predator is regularly distributed. Populations of each cell are assumed to firstly have local interactions of competition or selective predation and secondly disperse to the four nearest neighbouring cells. We establish a typology of spatial structures obtained from both interspecific competition and selective predation. These two types of interactions are able to create a sympatric zone and to cause its motion.
An Ordinary Differential Equation Model of Succession of Korean Pine Broadleaf Forest
Authors: Liu Jiagang , Chung K. W. , Chan H. S. Y.
Published: October 2003

An ordinary differential equation model for secondary succession of Korean pine broadleaf forest is presented. Monte Carlo models to simulate processes of tree death and seed sprouting are designed. Localization of the models and an ensemble counting method are suggested. Then the succession process of Korean pine broadleaf forest from disturbances, age structure and dynamic in the climax stage of the forest are described.
A Theoretical Analysis of the Role of Pyrophosphate,Fructose 6-P,1-Phosphotransferase in Energy Dissipation During the Conversion of Fructose 6-Phosphate to Fructose 1,6-Bisphosphate in Plant Cells
Authors: Liu Junli , Crawford John W. , Viola Roberto
Published: October 2003

A theoretical analysis of the effect of pyrophosphate,fructose 6-P,1-phosphotransferase (PFP) on energy dissipation in the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate is presented. The conclusion depends sensitively on whether PFP is in equilibrium, or catalyses a net flux in the directions of gluconeogenesis or glycolysis. It is shown that the conditions under which PFP is in equilibrium are rather restricted. Furthermore, experimental evidence supports the theoretical prediction that PFP catalyses a net flux in real systems. When PFP catalyses a net glycolytic flux, the system where both PFP and PFK are active always dissipates less energy than the system where only PFK exists. However, when PFP catalyses a net flux in gluconeogenesis, the PFK-PFP system dissipates more energy than the system where only PFK exists. By comparing the theoretical work with experimental results, the evidence suggests that PFP in higher plant cells catalyses a net glycolytic flux, and its presence increases the energetic efficiency of glycolysis.
Well Posedness of a Model of Population Dynamics of Infectious Diseases with "Roguing and Replanting" as Strategy of Control
Authors: Ramzi Azeddine
Published: October 2003

In this paper, we investigate existence and uniqueness of positive solutions of a model of infectious disease dynamics with a strategy for control of epidemics given in [1]. The model presents nonlinear and coupled equations which are transformed to integral functional equations with state dependent delay and solved using a fixed point theorem.
Assessing the Risk of Secondary Leukemia in Patients Treated for Hodgkin's Disease — A Report from the International Database on Hodgkin's Disease
Authors: Tsodikov A. D. , Loeffler M. , Yakovlev A. Yu.
Published: October 2003

Parametric models are used to investigate the time of leukemia latency in patients treated for Hodgkin's disease. A model of induced carcinogenesis provides a stable projection of the leukemia risk for times beyond the follow-up period. The model is applied to data collected in the International Data Base on Hodgkin's Disease. It permits to estimate the contributions of primary and of relapse treatment to the overall risk of induced leukemia. Latency periods appear to be identical after both treatments supporting the concept of induced leukemogenesis.
Non-Connected Branches of Alternative Stationary States — An Experimental Illustration
Authors: Coevoet M. A. , Hervagault J. F.
Published: October 2003

The steady-state and dynamic behavior of a partial glycolytic reaction sequence are investigated in cell-free extracts of yeast. Pyruvate kinase, adenylate kinase and glucose 6-phosphate isomerase cooperate to a multi-enzyme system centered around the 6-phosphofructose 1-kinase (6-PFK) and fructose 1,6-bisphosphatase (FBPase) cycle. The reaction system operates under thermodynamically open conditions maintained by a continuous supply of substrates, i.e. glucose 6-phosphate (Glc6P), ATP and phospho-enolpyruvate (PPrv) in a flow-through reaction chamber. Appropriate parametric conditions lead to the occurence of (two) coexisting and markedly different time-independent states in the metabolite concentrations and fluxes. It was already shown that for particular experimental conditions, changes of the influx adenylate energy charge, [AEC] IN , may cause transitions between these alternative steady states which are either reversible as it occurs in classical hysteresis phenomena, or irreversible (irreversible transitions) where the system is not able to switch back to its previous state even when the perturbation is reverted.

It was also shown numerically from the same qualitative model, that changes in the [AEC] IN , could also lead to the occurence of non-connected branches of alternative steady states [27]. In the present article, we propose the first experimental demonstration for the existence of such dynamic structures related to bistability and where no transition between the two coexisting stable branches of the bistable are physically possible and defining thus functionally non-equivalent states with distinct metabolite pattern.
Epidemics Between Bailey and Reed-Frost: A Stochastic Version of the Kermack and Mckendrick Model
Authors: Gielen J. L. W.
Published: October 2003

A model is developed that describes evolution with respect to time of an infectious disease introduced into a population of susceptibles. The proposed model incorporates at one end Bailey's simple stochastic epidemic and at the other end the Reed-Frost chain-binomial models and is the natural stochastic analogue of Kermack and McKendrick's deterministic model. The epidemic process is characterized by the size of the population and by two infectivity functions. The first one relates to a time dependent outside source of infection. The second one describes the infectivity of an individual as a function of his age-of-infection, that is the time elapsed since his own infection. The proposed model consists of a set of partial differential equations which governs, steered by the given infectivity functions, the evolution with respect to time of a set of density functions. These density functions deliver a complete stochastic description of the infectious-age structure of the population at any moment of time. An expression for the size of the epidemic, that is the probability distribution of the number of infectives, as a function of time follows. Also expressions for the expected arrival times of infectives, useful for the inverse problem, are developed. By letting time tend to infinity earlier results for the final size of the epidemic are confirmed.
Genetic Interpretation of Discrete Heredity II: Dynamics of Genes at One Locus with Genetic Drift in Small Population
Authors: Gillois Michel
Published: October 2003

The two 1944 and 1945 Malécot's papers are each a face of the same coin. The first paper is the study of gene frequency evolution in a small population as a Markoff chain. The second paper is the study of consanguinity coefficient evolution in a small population. Coefficient of consanguinity is defined between two homologous genes and have narrow relation with second moment of gene frequencies following the relation [Formula: see text] with [n>0,1<k<2N] and qn the frequence of an allelic form at the generation n, and [Formula: see text] the probability of identity for k homologous gens slamped at random in the population at the generation n to belong to j identity subsets [8].

In this paper we use the concept of "generalized genotype" in order to synthetize these two independent Malécot's results. Four roots control dynamics: [Formula: see text] and form the kernel of all genetic dynamics. All other roots introduced by mutation and/or zygotic selection derive by duplication from one of these four primitive roots.
Genetic Interpretation of Discrete Heredity III: Dynamics of Genes at one Locus with Genetic Drift and Mutations in Small Population
Authors: Gillois Michel
Published: October 2003

Allelic genes in each generation can not be considered as colored beans in a bag. Gene duplication, gene mutation, meiosis and mating rules structure the finite set of genes [20–24]. Mutation is a concept with three meanings. In this paper we study dynamics of allelic genes under mutational pressure. The dynamic is controlled by ten roots.
Species Richness in Fluctuating Environments: A Model Involving Interespecific Competition and Physiological Stress
Authors: Momo Fernando , Álvarez Martin , Álvarez Mariano
Published: October 2003

A general model linking environmental fluctuations and species richness is proposed. This model includes two important biological mechanisms. The first term describes the global negative effect of fluctuations on richness via stress and density-independent mortality; the second term represents the positive effect of perturbations on richness by competitive relaxation. Both effects are modeled as exponential functions. The model can be made richness-dependent putting the average competition coefficients as a function of the actual diversity. The system shows a non-trivial behavior since it has local maxima or minima in the richness function at intermediate values of environmental variability. The existence of these points depends on the ratio between stress sensitivity and competition coefficients. The discrete version of the model exhibits chaotic fluctuations when the initial richness is high.
A Look at Fractal Functions Through Their Fractional Derivatives
Authors: Stiassnie M.
Published: October 2003

A relationship between the Lipschitz-Holder exponent and the maximal possible order of derivative is used to look at fractal properties of functions representable by trigonometric series.
Insights into the Formation Process of the Retinal Vasculature
Authors: Kyriacos S. , Nekka F. , Cartilier L. , Vico P.
Published: October 2003

Growth phenomena have been studied extensively in natural sciences. This interest has been renewed since the introduction of the fractal concept. In an attempt to understand the origin of irregular phenomena, several computer models and theoretical approaches have recently been developed. Studies using fractal analysis of the retinovasculature have proposed diffusion-limited aggregation (DLA) one of the most popular models to explain the formation of the retina. A deeper investigation of the physiological laws ruling the development of the retinovasculature has, however, revealed static and dynamic discrepancies with DLA, leading to rejection of the DLA model, and reopening the debate. In light of comparison of the two formation processes and of the absence of a DLA structural characteristic in retinovasculature, we discuss the validity of some previously proposed models.
Statistical Properties of the LEDA Redshift Database
Authors: Amendola Luca , di Nella Helene , Montuori Marco , Labini Francesco Sylos
Published: October 2003

We present the statistical properties of large scale galaxy distribution in the LEDA redshift database. This catalog contains more than 40,000 redshifts over all the sky. We find that LEDA, although seriously affected by incompleteness, shows quite stable statistical properties. In particular, we have considered the behavior of the two points correlation function and of the power spectrum of the density fluctuations, and we have done several tests to check whether the incompleteness of the catalog affect these statistical quantities. Our conclusion is that galaxy distribution in this catalog has fractal properties up to the distance ~ 200h-1 Mpc with D = 2.1 ± 0.2, with no sign towards homogeneity: this result is statistically stable. Finally, we compare these results with those obtained in other redshift surveys, finding that this sample well reproduces the properties of galaxy distribution found in the different catalogs.
Multifractal Crossover in the Multiplicative Processes
Authors: Bershadskii A.
Published: October 2003

It is shown, using multifractal data on space-filling bearings, that there exists a multifractal crossover to an effective 'capacity' dimension in some multiplicative processes. This result is then used to interpret recent experimental data on multifractal structure of multiplicity distribution in electron-positron annihilation at high energies.
Categorization of Physiologically and Morphologically Characterized non-α/non-β Cat Retinal Ganglion Cells Using Fractal Geometry
Authors: Jelinek H. F. , Spence I.
Published: October 2003

Non-α/non-β cat retinal ganglion cell images were obtained from the published literature, and a homogeneous group of cells was chosen as a standard for each currently accepted cell type (γ, δ and ε). The NIH box-counting method was chosen to determine the fractal dimension (Df) of all cells. The 'standard' values allowed comparisons with other morphologically and physiologically non-α/non-β classified cell types in the literature. We suggest, based on fractal analysis of the dendritic trees, that the morphologically defined γ, δ, and ε cells are distinct types. The W-tonic and W-phasic cell types were further divided into 2 subcategories (W-tonic1, W-tonic2, W-phasic1, W-phasic2). The fractal dimension, of the ε cells being equivalent to the W-tonic1 group and γ cell type equivalent to the W-phasic1 group. Delta cells may be equivalent to either the W-tonic2 or the W-phasic2 group. We discuss the value of the fractal dimension as an added morphological parameter for future morphophysiological classification schemes of vertebrate retinal ganglion cells.
Deterministic Tree Networks for Fluid Flow: Geometry for Minimal Flow Resistance Between a Volume and One Point
Authors: Bejan Adrian , Errera Marcelo R.
Published: October 2003

The function of many natural flow systems is to connect by a fluid flow a finite-size volume and one point. This paper outlines a strategy for constructing the architecture of the volume-to-point path such that the flow resistance is minimal (constructal theory1). The given volume is viewed as an assembly of volume elements of various sizes. The main discovery is that the shape of each element can be optimized such that the elemental volume-to-point flow resistance is minimal. This optimization principle applies at every volume scale. The smallest volume element contains a fluid saturated porous medium with Darcy flow, which is collected by and channeled through a high permeability path (e.g., fissure) to one point on the element boundary. The geometric optimization is repeated for larger volume elements, which are constructs (assemblies) of optimized smaller volumes. The flow integrated over each new assembly is channeled through a high-permeability path to a point on the side of the assembly. One remarkable feature of the emerging minimal-resistance flow path is that the high-permeability channels of the various volume elements form a tree network which is completely deterministic. The interstices of the network are filled with low permeability porous medium. The method is extended to applications where the high-permeability paths are empty spaces (e.g., parallel-plate channels). It is shown that when the total void volume is constrained it can be distributed optimally among the volume elements to further decrease the overall flow resistance.
Influence of Element Types on Numeric Error for Acoustic Boundary Elements
Authors: Marburg Steffen , Schneider Stefan
Published: October 2003

Continuous interpolation of the sound pressure is favored in most applications of boundary element methods for acoustics. Few papers are known to the authors in which discontinuous elements are applied. Mostly they were used because they guarantee C1 continuity of the geometry at element edges. The effect of superconvergence is known for boundary element collocation on discontinuous elements. This effect is observed if the collocation points are located at the zeroes of orthogonal functions, e.g. at the zeroes of the Legendre polynomials.

In this paper, we start with a review of related work. Then, formulation of discontinuous elements and position of nodes on the element are presented and discussed. One parameter controls the location of nodes on the element. The major part of the paper consists of the investigation of the computational example of a long duct. For that, the numeric solution is compared with the analytic solution of the corresponding one-dimensional problem. Error dependence in terms of frequency, element size and location of nodes on discontinuous elements is reported. It will be shown that the zeroes of the Legendre polynomials account for an optimal position of nodes. Similar results are observed for triangular elements. It can be seen that the error in the Euclidean norm changes by one or two orders of magnitude if the location of nodes is shifted over the element. It can be seen that the optimal location varies with the wave-number although remaining in the vicinity of the zeroes of orthogonal functions. The irregular mesh of a sedan cabin compartment accounts for the second example. Optimal choice of node position is confirmed for this example. One of the key results of this paper is that discontinuous boundary elements perform more efficiently than continuous ones, in particular for linear elements. This, however, further implies that nodes are located at the zeroes of orthogonal functions on the element.
Adaptive Multigrid for Helmholtz Problems
Authors: Bartsch Guido , Wulf Christian
Published: October 2003

Solving Helmholtz problems for low frequency sound fields by a truncated modal basis approach is very efficient. The most time-consuming process is the calculation of the undamped modes.

Using traditional FE solvers, the user has to provide a mesh which has at least six nodes per wavelength in each spatial direction to achieve acceptable results. Because the mesh size increases with the 3rd power of the highest frequency of interest, this uniform dense mesh approach is a very expensive way of creating a modal space.

However, the number of modes and the accuracy of the modal basis directly influences the solution quality. It is well known that the representation of sound fields by modal basis functions φi is optimal with respect to the L2 error norm. This means that having a modal basis Φ := {φi, i = 1⋯n}, the distance between true and approximated sound field takes its minimum in the mean square.

So, it is necessary to have a FE basis which also minimizes the discretization error when computing the modal basis. One can reach this goal by applying adaptive mesh refinements. Additionally, this yields the opportunity of using fast multigrid methods to solve discrete eigenvalue problems.

In context of this presentation we will discuss the results of our adaptive multigrid algorithms.
A Guideline for Using the Multi-Domain BEM for Analyzing the Interior Acoustic Field
Authors: Jeong Ji-Hoon , Ih Jeong-Guon , Lee Byung-Chai
Published: October 2003

The calculation efficiency of the conventional single-domain acoustic BEM (SBEM) is important for analyzing large scaled or complicated acoustic cavity systems. Although the multi-domain BEM (MBEM) has been developed to deal with such complex shaped and large size acoustic systems effectively, it is generally known that the MBEM requires more computation time and computer memory space than the SBEM. However, if the proper division were applied on a single cavity, it is thought that the MBEM could be the better method than the SBEM in the viewpoint of accuracy and efficiency. This might be possible when one reminds the fact that the effort in the MBEM calculations also depends strongly on the shape of the total acoustic cavity. In this article, the general computational characteristics of the MBEM for analyzing the interior acoustic fields are investigated to provide a guideline in the division of a single cavity into several subdomains for having better computational performance than using the SBEM. A two-dimensional long duct comprised of a number of linear elements is taken as a demonstration example. It is clearly shown that the modification of MBEM model through the present guidelines achieves more accurate and efficient computation than using the SBEM.
Application of Fast Methods for Acoustic Scattering and Radiation Problems
Authors: Schneider Stefan
Published: October 2003

Our work is devoted to the solution of large scale (kl = 10…100π) three dimensional radiation and scattering problems covered by the time harmonic Helmholtz equation. We present an application of the Regular Grid Method and Multilevel Fast Multipole Method to acoustic scattering problems. These methods lead to a memory requirement of [Formula: see text] that enables us to solve scattering or radiation problems with several ten-thousands of unknowns. In a computational examples we show the efficiency of these methods.
Does a Real Material Behave Fractionally? Applications of Fractional Differential Operators to the Damped Structure Borne Sound in Viscoelastic Solids
Authors: Nolte Bodo , Kempfle Sigmar , Schäfer Ingo
Published: October 2003

Time dependent analysis of the dynamic damped behavior of continua are mathematically modelled by partial differential equations. One obtains uniqueness, existence and stability (well posed problems) by the implementation of the correct initial boundary conditions. However, by taking memory effects into consideration, any change in the past of the system changes the future dynamic behavior. Classical damping descriptions fail when describing the behavior of many materials, like teflon. This is because in classical theory the operators are local ones. The implementation of fractional time derivatives into the partial differential equations is an alternative technique to overcome these problems. Thereby the time derivative operator is a global one, memory effects in structure borne sound can be calculated. In this paper the theory of fractional time derivative operators and their application in continuum mechanics is presented. The main result when using this method for damping behavior is that a global operator is needed which takes the whole history into account. We call this theory the functional calculus method instead of the well-known fractional calculus with the use of initial conditions. In order to show the efficiency of this method the calculated impulse response of a viscoelastic rod is compared with measurements. It is shown that the damping behavior is described much better than by other models with comparably few parameters. Moreover, it is the only one that works in a wide frequency range and can describe the dispersion of the resonance frequencies. The implementation of this damping description in a Boundary Element Code is an application of dynamics of 3D continua in the frequency domain.
Mesh Coarsening for the Finite and the Boundary Element Method in Acoustics
Authors: Giljohann Dietmar
Published: October 2003

The process of mesh coarsening describes the reduction and simplification of a highly detailed mesh in such a way that the original geometry is best possible preserved. The earliest coarsening algorithms were developed for real time visualizations in the upcoming field of computer graphics and later on adopted for some element topologies of the finite element method (FEM). An algorithm is presented in this article which applies the mesh decimation process to the requirements of both the FEM and the Boundary Element Method (BEM) in acoustics. The capabilities of the algorithm in order to significantly reduce the CPU times for both numerical methods are shown.
Time-Domain Poroelastic Green's Functions
Authors: Hanyga Andrzej
Published: October 2003

A method previously developed for asymptotic solution of systems of integro-differential equations with singular memory is applied to the determination of the time-domain asymptotic Green's function of Biot's poroelasticity. Asymptotic time-domain Green's functions are constructed in a neighborhood of the wavefronts. The general anisotropic medium as well as the isotropic case are considered.
A Suggested Conditional Modus Ponens
Authors: Vincent Nicole , Dujet Christiane
Published: October 2003

In this paper, in view of some paradoxical situations encountered in applying the Modus Ponens to Inference procedures in rule-based systems, we propose a new approach to perform the generalized Modus Ponens of Zadeh.

Specifically, truth evaluations of conditional fuzzy information will be defined and used in Modus Ponens, opening the way to a unified framework for the aggregation of rules.
Reasoning with Uncertainty in Deductive Databases and Logic Programs
Authors: Ng Raymond T.
Published: October 2003

Of all scientific investigations into reasoning with uncertainty and chance, probability theory is perhaps the best understood paradigm. Nevertheless, all studies conducted thus far on the semantics of quantitative logic programming have been restricted to non-probabilistic semantical characterizations. In this paper, we survey the major features and summarize the major results of the various frameworks that we have developed to rectify this situation. In the first part of this paper, we outline a deductive database framework which is expressive enough to represent such probabilistic relationships as conditional probabilities, Bayesian updates, probability propagation and mutual exclusion. We propose a fixpoint theory and a probabilistic model theory, and characterize their inter-relationships. As the aforementioned language is monotonic in nature, we discuss in the second half of this paper three approaches of supporting non-monotonic probabilistic reasoning. In the first approach, we use a non-monotonic negation operator. In the second, we use the Dempster-Shafer rule of combination. Finally, we discuss how empirical probabilities can be supported in monadic deductive databases.
Interval-Valued Degrees of Belief: Applications of Interval Computations to Expert Systems and Intelligent Control
Authors: Nguyen Hung T. , Kreinovich Vladik , Zuo Qiang
Published: October 2003

Usually, expert systems use numbers to describe the experts' degree of belief in their statements. In practice, however, it is difficult to assign an exact numerical value to the expert's degree of belief. At best, we can get an interval of possible values. This fact leads to the use of interval-valued degree of belief. When intervals are used to describe degrees of belief, then computations with intervals must be used to process them. In this paper, we describe applications of such interval computations to expert systems and to intelligent control.
Structure of Uninorms
Authors: Fodor János C. , Yager Ronald R. , Rybalov Alexander
Published: October 2003

An exhaustive study of uninorm operators is established. These operators are generalizations of t-norms and t-conorms allowing the neutral element lying anywhere in the unit interval. It is shown that uninorms can be built up from t-norms and t-conorms by a construction similar to ordinal sums. De Morgan classes of uninorms are also described. Representability of uninorms is characterized and a general representation theorem is proved. Finally, pseudo-continuous uninorms are defined and completely classified.
A Modified OWA Operator and its Use in Lossless DPCM Image Compression
Authors: Mitchell H. B. , Estrakh D. D.
Published: October 2003

The ordered weighted averaging (OWA) operator of Yager was introduced to provide a method for aggregating several inputs which lies between the Max and Min operators. The fundamental aspect of the OWA operator is a reordering step in which the input arguments are re-arranged according to their actual relative value. In this paper we describe a modified OWA operator in which the input arguments are not re-arranged according to their actual relative values but rather according to their estimated relative values. We describe an unusual application of this operator to lossless image compression.
Admissible Partitions of Fuzzy Finite State Machines
Authors: Malik D. S. , Mordeson John N. , Sen M. K.
Published: October 2003

In this paper we introduce the concept of a covering of a ffsm by another, admissible partitions and relations of a ffsm, μ-orthogonality of admissible partitions, irreducibile ffsm, and the quotient of a ffsm induced by an admissible partition of the state set.
Heteroepitaxial Film of Monolayer Graphene/Monolayer h-BN onNi(111)
Authors: Tanaka T. , Ito A. , Tajima A. , Rokuta E. , Oshima C.
Published: October 2003

Heteroepitaxial multilayers, consisting of graphene/hexagonal boron nitride (h-BN) films on Ni (111), have been investigated by means of vibrational spectroscopy, low energy electron diffraction and Auger electron spectroscopy. Vibrational spectra of the heteroepitaxial film show the appearance of transverse optical ( TO⊥) modes with out-of-plane polarization at 100 meV of the monolayer h-BN, in contrast to the softening phonon at 90 meV on the pristine system of monolayer h-BN on Ni (111). The findings strongly suggest that the interfacial bonds between h-BN and Ni (111) weaken due to the formation of monolayer graphene.
The Morphology of Fracture Surfaces: A Tool for Understanding Crack Propagation in Complex Materials
Authors: Bouchaud Elisabeth
Published: October 2003

We review experiments concerning the quantitative morphology of the fracture surfaces of various materials, at different length scales, using different techniques. These experiments could separate "universal" morphological parameters from material-dependent ones. We show how these results have been at the basis of theoretical developments on crack propagation and damage in heterogeneous materials.
The Kinetic Study of H2S Formation and Desorption on the S/Pt(111) Surface by Computer Simulation
Authors: Moshfegh A. Z. , Zakeri K. H.
Published: October 2003

In this investigation, we have studied the kinetics and mechanism of formation and desorption of H 2 S on the Pt (111) surface using a kinetic random walk model. The effect of temperature on the H 2 S formation was studied in the range of 85–150 K. It was observed that a maximum amount of H 2 S is formed at 90 K and the amount is reduced at higher temperatures. H 2 S production yield as a function of time at different initial sulfur coverage ranging from 0.02 to 0.33 ML (1 ML ≃ 1 × 1015 atoms/cm 2) was also examined. It was obvious that as the initial S coverage increases, the rate of H 2 S formation rapidly increases and reaches a maximum value and then declines gradually. Furthermore, according to our simulated TPD spectra, for β = 1 K/s the maximum desorption rate occurs at Tp = 107.2 K . In addition, analysis of simulated TPD spectra of H 2 S desorption showed in an activation energy of H 2 S desorption Ed = 27.2 kcal/mol . Finally, the obtained simulated results were compared with the experimental data reported very recently, showing excellent agreement.
Studies of Ag/Fe Interfacial Free Energies by Biaxial Zero Creep Experiments
Authors: An Bing , Zhang Tong-Jun , Yuan Chao , Cui Kun
Published: October 2003

Biaxial zero creep experiments based on the Josell model were performed on Ag/Fe multilayer thin films to determine their interfacial free energies. Various multilayer samples on stiff wafers prepared by RF magnetron sputtering were subjected to annealing of long duration at 550°C, while a substrate curvature technique was employed for real-time film stress monitoring. Sufficient plastic flow in films makes possible a zero creep equilibrium state to present during this isothermal process, and as a result the interfacial free energies in multilayer interfaces are equilibrated with the elastic strain energies arising from the substrate bending. There is no collapse in the annealed multilayer structures. They are still stably layer-built and exhibit a column grain distribution. XRD results show that Ag and Fe layers have (111) and (110) preferred orientations, respectively. In accordance with a revised Josell model, the equilibrium stresses were measured and the Ag (111)/ Fe (110) interface free energy at 550°C was found to be 0.97 ± 0.13 J/m 2.
Optical Properties of Excitons in Quantum Well Wires Under the Magnetic Field
Authors: Kasapoglu E. , Sari H. , Sökmen I.
Published: October 2003

The binding energy of excitons in quantum well wires of GaAs surrounded by Ga 1-x Al x As was calculated in an effective mass approximation with the use of the variational approach. Results obtained show that the exciton binding energies depend on the sizes of the wire and the strength of the magnetic field. The exciton theory was then used to calculate the linear absorption coefficient of HH1–C1 excitons by varying the wire dimensions and magnetic field values.
Motions and Reactions of Single Adsorbed Molecules Induced by Vibrational Excitation with STM
Authors: Ueba H.
Published: October 2003

Recent progress in the study of motions and reactions of single adsorbed molecules on metal surfaces induced by inelastic tunneling electrons with a scanning tunneling microscope (STM) is given an overview, with the focus on our current theoretical understanding of the elementary processes behind these phenomena. The selected topics include rotation and dissociation of O 2 on Pt (111), rotation of a C 2 H(D) 2 on Cu (100), lateral hopping of CO on Pd (110), lateral translation and desorption of NH 3 on Cu (100), and controlled manipulation of chemical transformation as well as bimolecular reaction of coadsorbed species on metal surfaces. Brief descriptions are presented of how an adsorbate to overcome the potential barrier for motion and reaction by incoherent stepwise and coherent single multistep climbing of the vibrational ladders in the potential well along the reaction coordinate, and indirect excitation of the reaction coordinate mode via anharmonic coupling to the vibrational mode excited by tunneling current. Elementary processes of the mode-selective control of different motions are also discussed in conjunction with a recent experimental result of lateral hopping and desorption of a single NH 3 molecule on Cu (100). Although still at a premature stage, these novel phenomena open a new world of "nano-surface-science," in which the manipulation and reaction of single adsorbates, and synthesis of a new molecular system are realized by a selective excitation of the relevant vibrational mode by tunneling electrons with an STM.
Scattering and Transmission of Elastic Waves from an Interface Between Two Planar Waveguides
Authors: Tamine M.
Published: October 2003

The scattering and transmission properties of elastic waves in a two-dimensional waveguide constructed from two dissimilar square lattices which exhibit a strain field at the interface, have been theoretically studied. The strain field is described by the existence of the local forces at an interface different to those occurring outside the surrounding interface. The theoretical approach using the matching procedure for calculating phonon scattering at the interface domain boundary is also presented. The reflection and transmission probabilities in the scattering region are calculated and illustrated for the longitudinal and transversal propagating modes in the normal incidence of the elastic wave. The conductance properties in full accordance with the Landauer–Büttiker description of electron transport are also calculated. The asymmetric Fano resonance type may appear in the phonon transmission spectra due to the coherent coupling between the two-dimensional crystal phonons and the localized vibration modes on the interface boundary. A discussion on the vibrational waves in the scattering region is given. We also show how even a simple interface in a two-dimensional situation can be used as a phonon filter, and how phonons can be used to probe an interface.
Direct Estimation of the Fractal Dimensions of a Fracture Surface of Rock
Authors: Zhou H. W. , Xie H.
Published: October 2003

A direct determination of the fractal dimensions of a fracture surface is essential for a better understanding of its complete topographic characteristics. In this paper, a laser profilometer is employed to measure the topography of a rock's fracture surface. With the use of the triangular prism surface area and projective covering methods, the resultant data set enables us to directly determine the fractal dimensions of a rock's fracture surface. Moreover, a new method, referred to as the cubic covering method, is proposed. The theoretical issues of fractal dimension estimation are also discussed.
Single-Beam Z-Scan: Measurement Techniques and Analysis
Authors: Chapple P. B. , Staromlynska J. , Hermann J. A. , Mckay T. J. , Mcduff R. G.
Published: October 2003

The Z-scan technique is a popular method for measuring degenerate (single frequency) optical nonlinearities using a single laser beam. In order to perform reliable measurements, it is necessary to carefully characterize and control a number of experimental parameters, such as the beam quality, the power and temporal characteristics of the laser, the collection aperture size and position, the sample reflectivity, sample thickness and imperfections in the sample. Failure to control these parameters leads to inaccurate determinations of the nonlinearities. In this paper, we review the theory of Z-scan and examine each of these issues from experimental and theoretical viewpoints. This work will be of interest to anyone who performs Z-scan experiments and to those interested in optical power limiting and nonlinear optical propagation.