bluuebunny/crossref_metadata_2025 huggingface dataset:
A Quality of Service Framework for Object-Oriented Architectures
Authors: Selic Bran
Published: August 2003

Most development and system specification languages do not provide facilities for a formal and complete declaration of the expected hardware and software environment for which a system is targeted. This type of information can be used to determine whether a software specification is compatible with a particular computing environment. In this paper we describe an approach, based on a generic "quality of service" framework, that provides such a facility for a broad category of object-oriented architectural definition languages. A formal model of this facility is also provided, including rules for determining compatibility between different computing environments.
An Approach for Adaptive Fault Tolerance in Object-Oriented Open Distributed Systems
Authors: Shokri Eltefaat , Hecht Herbert , Crane Patrick , Dussault Jerry , (Kane) Kim K. H.
Published: August 2003

Effective fault-management in emerging complex distributed applications requires the ability to dynamically adapt resource allocation and fault tolerance policies in response to possible changes in environment, application requirements, and available resources. This paper presents an architecture framework of an Adaptive Fault Tolerance Management (AFTM) middleware using a CORBA-compliant object request broker resting on the Solaris open system platform. The paper also discusses approaches which have been tested through an AFTM prototyping effort.
Incremental Verification of Architecture Specification Language for Real-Time Systems
Authors: Tsai Jeffrey J. P. , Sistla A. P. , Sahay Avinash , Paul Ray
Published: August 2003

The concept of software architecture has recently emerged as a new way to improve our ability to effectively construct large scale software systems. However, there is no formal architecture specification language available to model and analyze temporal properties of complex real-time systems. In this paper, an object-oriented logic-based architecture specification language for real-time systems is discussed. Representation of the temporal properties and timing constraints, and their integration with the language to model real-time concurrent systems is given. Architecture based specification languages enable the construction of large system architectures and provide a means of testing and validation. In general, checking the timing constraints of real-time systems is done by applying model checking to the constraint expressed as a formula in temporal logic. The complexity of such a formal method depends on the size of the representation of the system. It is possible that this size could increase exponentially when the system consists of several concurrently executing real-time processes. This means that the complexity of the algorithm will be exponential in the number of processes of the system and thus the size of the system becomes a limiting factor. Such a problem has been defined in the literature as "state explosion problem". We propose a method of incremental verification of architectural specifications for real-time systems. The method has a lower complexity in a sense that it does not work on the whole state space, but only on a subset of it that is relevant to the property to be verified.
Sequence Specification for Concurrent Object-Oriented Applications
Authors: Wang Yamin , Vishnuvajjala Ramakrishna V. , Tsai Wei-Tek
Published: August 2003

Modeling synchronization among threads is important for the specification, design, and testing of concurrent object-oriented applications such as those written in Java. This paper proposes Synchronized Method Sequence Specification (SMtSS), a mechanism for specifying synchronization requirements among multiple threads sharing a common object. SMtSS identifies two kinds of synchronization among the sharing threads, internal and external ones, and explicitly specifies the synchronization scenarios. SMtSS also proposes notations for specifying different data integrity constraints on method executions. This paper also proposes specification-slicing techniques to obtain specific behavior of certain threads from SMtSS specifications. Finally, this paper discusses how SMtSS specifications can be useful in the design and testing of concurrent object-oriented applications in Java.
The Role of Nonmonotonic Representations in Requirements Engineering
Authors: Antoniou Grigoris
Published: August 2003

This paper discusses the significance of nonmonotonic reasoning, a method from the knowledge representation area, to mainstream software engineering. In particular, we discuss why the use of defaults in specifications is an adequate way of addressing some of the most important problems in requirements engineering, such as: The problem of identifying and dealing with inconsistencies; evolving system requirements; requirements prioritization; and the quality of specifications with respect to naturalness and compactness. We argue that these problems need to be addressed in a principled, formal way, and that default reasoning provides adequate mechanisms to deal with them.
Matching Single-Sort Algebraic Specifications for Software Reuse
Authors: Crespo Rui Gustavo
Published: August 2003

Software reuse may only be put into practice if we make available matching mechanisms between user needs and reusable components. The matching mechanisms should also be powerful enough to allow transformations of the user components that, while maintaining correctness, increase the possibilities of use of repository components by the user. In this paper we propose to use the mathematical framework of category theory to develop matching mechanisms for single-sort algebraic specifications that would allow the automatic retrieval and data adaptation of correct programs. We identify two types of specification matching, isomorphic and composite.
Enhancing CASE Environments by Using Linguistics
Authors: Burg J. F. M. , van de Riet R. P.
Published: August 2003

In this paper it is argued that CASE environments could and should be enhanced considerably by using theories and knowledge from linguistics. The environments should 'know' about the language of their users and the domains they are used for. By basing the modeling techniques supported by the CASE tool on linguistic theories and by incorporating Natural Language parsing and generating tools, the CASE environment is able to handle the users' language in an accurate way. More specifically, the CASE environment deals with the meaning of words, instead of the meaningless strings themselves. These meanings, which are retrieved from an online lexicon, are linked to the words used in both the requirements documents as well as in the conceptual models in order to achieve a certain degree of consistency between the two of them. The base structure of these models is automatically derived by analyzing the textual requirements documents that describe the domain under consideration. This Natural Language analysis consists of parsing the texts and retrieving the word meanings that corresponds to concepts that may be of interest for modeling this domain accurately. Furthermore, the resulting models can be validated by people who are not familiar with the modeling notations used, by paraphrasing the models to Natural Language sentences. This paper mainly focuses on the profits gained by using linguistic knowledge in CASE environments, on the philosophy behind this approach and on three specific Natural Language components: the lexicon, Natural Language analysis and text generation for requirements validation.

This article is based on the paper "Truly Intelligent CASE Environments Profit from Linguistics" [7], which was presented during the SEKE conference in Madrid (June 1997).
Results of the Application of a Linguistic Approach to Object-Oriented Analysis
Authors: Moreno Ana M.
Published: August 2003

In this paper, we present a linguistic approach in order to achieve the object oriented analysis (OOA) process in a systematic way. The approach is based on the definition of a formal correspondence between a subset of structures from linguistic world, called linguistic patterns, and a subset of structures from conceptual world, called conceptual patterns. This correspondence provides a solid basis in order to develop the conceptual models that represent the problem and its solution. One conceptual model will be used to represent the static part of the system, and another will represent system behavior.
Organizing the Software Development Process Knowledge: An Approach Based on Patterns
Authors: de Vasconcelos Francisco M. , Werner Cláudia Maria Lima
Published: August 2003

This paper describes an approach to support software development process descriptions in the context of the Memphis Environment (a Reuse Based Software Development Environment), allowing the organization of a software development asset, i.e., the process knowledge. The approach uses software patterns to organize the information, and provides a tool that handles the process descriptions as a source of solutions to problems detected by project management. It enhances the environment features in terms of project management support, process modeling capability, and process evolution support.
Software Configuration Management for a Reusable Software Library within a Software Maintenance Environment
Authors: Kwon Oh Cheon , Boldyreff Cornelia , Munro Malcolm
Published: August 2003

Software Configuration Management and software reuse are now generally considered to be important technologies in software engineering. Both have been proposed for making a significant improvement in productivity and quality. However, these two technologies have been investigated separately. In order to make Software Configuration Management and reuse more effective, both approaches require to be introduced into a development or maintenance environment together. The authors have developed a process model for Maintenance with Reuse (MwR) to support Software Configuration Management for a reuse library within a maintenance environment. As software reuse and Software Configuration Management as well as software reuse and software maintenance have many similarities in their activities, and these areas can therefore be integrated within a software maintenance environment. An integrated approach to the common areas of these different activities will greatly contribute to the productivity and quality of software. This paper will address an integrated approach that can overcome some of the barriers that exist in software maintenance and reuse. A process model of an integrated approach has been created and validated using Process Weaver. In order for the reuse library to allow accesses from many potential reusers, the process model has been implemented on the WWW. The paper describes an integrated process model and its prototype to support change and version control for evolution of software components within both a reuse library and a legacy system.
ISF: A Visual Formalism for Specifying Interconnection Styles for Software Design
Authors: Mancoridis Spiros
Published: August 2003

We have developed a framework for specifying high-level software designs. The core of the framework is a very simple visual notation. This notation enables designers to document designs as labelled rectangles and directed edges. In addition to the notation, our framework features a supporting formalism, called ISF (Interconnection Style Formalism). This formalism enables designers to customize the simple design notation by specifying the type of entities, relations, legal configurations of entities and relations, as well as scoping rules of the custom notation.

In this paper we present the formal definition of ISF and use ISF to specify two custom design notations. We also describe how ISF specifications, using deductive database technology, are used to generate supporting tools for these custom notations.
An Object-Oriented Design Complexity Metric Based on Inheritance Relationships
Authors: Shih Timothy K. , Lin Yule-Chyun , Pai Wen C. , Wang Chun-Chia
Published: August 2003

Software metrics serve as a significant issue to improve software quality. It is an important research of software engineering. In line with the methodologies of object-oriented analysis and design widely developed, many software metrics techniques have been proposed. However, not many focus on the metrics evaluation of an inheritance hierarchy. In this paper, we propose a novel concept named unit repeated inheritance (URI) in Z notation to realize object-oriented software metrics. The approach describes an inheritance level technique (ILT) method as a guide to measure the software complexity of an inheritance hierarchy. The measures of inheritance metrics are formed based on the proposed mechanism. Also, we use Lex and Yacc to construct a windowing tool which is used in conjunction with a conventional C++ programming environment to assist a programmer to analyze and measure his/her C++ programs.
Separating Classes of Groups by First-Order Sentences
Authors: Nies André
Published: August 2003

For various proper inclusions of classes of groups [Formula: see text], we obtain a group [Formula: see text] and a first-order sentence φ such that H⊨φ but no G∈ C satisfies φ. The classes we consider include the finite, finitely presented, finitely generated with and without solvable word problem, and all countable groups. For one separation, we give an example of a f.g. group, namely ℤp≀ ℤ for some prime p, which is the only f.g. group satisfying an appropriate first-order sentence. A further example of such a group, the free step-2 nilpotent group of rank 2, is used to show that true arithmetic Th(ℕ,+,×) can be interpreted in the theory of the class of finitely presented groups and other classes of f.g. groups.
Hurwitz Equivalence in the Braid Group B3
Authors: Ben-Itzhak T. , Teicher M.
Published: August 2003

In this paper we prove certain Hurwitz equivalence properties of Bn. In particular we prove that for n = 3 every two Artin factorizations of [Formula: see text] of the form Hi1 ⋯ Hi6, Fj1 ⋯ Fj6 (with ik, jk ∈ {1, 2}) where {H1, H2}, {F1, F2} are frames, are Hurwitz equivalent. The proof provided here is geometric, based on a newly defined frame type.

The results will be applied to the classification of algebraic surfaces up to deformation. It is already known that there exist surfaces that are diffeomorphic to each other but are not deformations of each other (Manetti's example). We construct a new invariant based on Hurwitz equivalence of factorizations, to distinguish among diffeomorphic surfaces which are not deformation of each other. The main result of this paper will help us to compute the new invariant.
On the Images of ℕ-Rational Sequences Counting Multiplicities
Authors: Honkala Juha , Ruohonen Keijo
Published: August 2003

A mapping ϕ:ℤ → ℤ is called piecewise affine if there exist integers a≥ 1 and uj≥ 1, vj for 0≤ j<a such that ϕ(an+j)=ujn+vj whenever n∈ ℤ and 0≤ j<a. We prove that if s=(s(n))n≥ 0 and t=(t(n))n≥ 0 are ℕ-rational sequences such that s takes each value exactly as many times as t, then there exists a piecewise affine mapping ϕ:ℤ → ℤ such that s(n)=t(ϕ(n)) for almost all n≥ 0. As an application we solve the HD0L language equivalence problem in some cases.
Homological Finite Derivation Type
Authors: Alonso Juan M. , Hermiller Susan M.
Published: August 2003

In 1987, Squier defined the notion of finite derivation type for a finitely presented monoid. To do this, he associated a 2-complex to the presentation. The monoid then has finite derivation type if, modulo the action of the free monoid ring, the 1-dimensional homotopy of this complex is finitely generated. Cremanns and Otto showed that finite derivation type implies the homological finiteness condition left FP3, and when the monoid is a group, these two properties are equivalent. In this paper we define a new version of finite derivation type, based on homological information, together with an extension of this finite derivation type to higher dimensions, and show connections to homological type FPnfor both monoids and groups.
Lyndon's Group is Conjugately Residually Free
Authors: Lioutikova Ekaterina
Published: August 2003

Lyndon's group FZ[x] is the free exponential group over the ring of integral polynomials Z[x]. This group, introduced by Lyndon in the 1960s, continues to be of interest to group theorists due to its importance in the study of first-order properties of free groups, in particular, equations over free groups. One of the crucial results of Lyndon's study was that the group FZ[x] is fully residually F; i.e. for any finite collection of nontrivial elements in FZ[x] there exists a homomorphism φ : FZ[x] → F which is the identity on F and maps the given elements of FZ[x] into nontrivial elements of F. The importance of FZ[x] was further emphasized when Kharlampovich and Myasnikov proved in [3] that a finitely generated group is fully residually free if and only if it is embeddable into FZ[x]. Lyndon's group and its subgroups play a vital role in the technique employed by O. Kharlampovich and A. Myasnikov in their solution of the famous Tarski problem on the decidability of the elementary theory of a free group (see [4, 5]).

In this paper, we show that Lyndon's group is conjugately residually free, i.e. it is possible to map FZ[x] to the free group F preserving the nonconjugacy of two elements. This result is a further step towards the understanding of the properties of FZ[x]; moreover, it is closely related to the problem of "lifting solutions" of equations from F to FZ[x], since our result implies that the solutions can indeed be "lifted" from F to FZ[x] for equations of the type x-1 c1 x = c2.

The structure of Lyndon's group, described by A. Myasnikov and V. Remeslennikov in [8], involves an infinite sequence of free constructions of a specific type, called free extensions of centralizers. For more results on residual properties of certain types of free constructions, see also the works of Ribes, Segal and Zalesskii (for example [9]).
On the Asphericity of Relative Group Presentations of Arbitrary Length
Authors: Metaftsis V.
Published: August 2003

In the present note we investigate asphericity (as defined in [2]) of the relative group presentation [Formula: see text] with a,b,c ∈ H and p,q,r>1. Results similar to those proved in [1, 2, 7] are obtained.
The Complexity of Dualisability: Three-Element Unary Algebras
Authors: Clark D. M. , Davey B. A. , Pitkethly J. G.
Published: August 2003

We solve the dualisability problem in the class of three-element unary algebras. Our aim in tackling this class is to demonstrate the difficulty of the general dualisability problem. We also want to investigate the extent to which the dualisability of a finite algebra is a finiteness condition on the quasi-variety it generates.
Logical Distinction Between Diagrammatic and Cohen–Lyndon Asphericity
Authors: Biskup Igor
Published: August 2003

We resolve the status of the implication CLA ⇒ DA in the negative by showing that the two-dimensional model of the group presentation (a, b : a, b-1 aba-1 b-1) is DA but not CLA. This settles a question that has been addressed in [2, 7, 10, 11].

In 1941, Whitehead posed the question whether asphericity is a hereditary property for two-dimensional CW complexes. This question remains unanswered. Out of its study developed the formulation of several combinatorial properties for group presentations that are sufficient (but not necessary) for asphericity of the associated two-dimensional model. The logical relationships between these flavors of asphericity are just partially understood. In this article we show that two of these flavors of asphericity are in fact distinct. As a consequence, all of the known flavors are distinct.

An argument of Lyndon and Schupp [5, III Property 10.6] shows that if a two-dimensional CW complex K is Cohen–Lyndon aspherical (CLA), then K is also diagrammatically aspherical (DA). The status of the reverse implication had been open prior to this writing. We will present an alternative proof for the implication CLA ⇒ DA and demonstrate that every spherical picture over the presentation (a, b : a, b-2 aba-1) can be reduced without insertions of dipoles, thus concluding that the presentation is DA. A straightforward argument shows that the presentation cannot be CLA.

Our main tool is the theory of spherical pictures and picture moves of which we will give a short survey.
Simple Deviation Analysis of Two-Dimensional Viral DNA Walks
Authors: Hsu Tai-Hsin , Nyeo Su-Long
Published: August 2003

We consider the method of two-dimensional DNA walks based on three independent groups of mapping rules for 21 DNA sequences of animal and plant viruses, and for the sequences of irrational and random numbers. This method provides a visualization tool for the determination of the regional abundance of nucleotides in DNA sequences. By defining a statistical deviation and a maximum-deviation ratio for a DNA walk, we find that the maximum-deviation ratios for the 21 viral DNA sequences are generally larger than those of the random-number sequences of same lengths. It is shown that the viral DNA sequences generally have the smallest maximum-deviations with the same mapping group, and that greater difference between CG and AT contents is associated with larger maximum-deviation ratio. Also it is possible to distinguish a viral DNA sequence from a random-number sequence if the lengths of the sequences are longer than 2000 base-pairs. Other possible applications of the two-dimensional DNA walks are mentioned.
Modeling Mating Patterns Given Mutual Mate Choice: The Importance of Individual Mating Preferences and Mating System
Authors: Bessa-Gomes Carmen , Clobert Jean , Legendre Stéphane , Møller Anders Pape
Published: August 2003

When we consider structured populations with sexual reproduction, the distribution of characters among mating pairs may influence the population biology, namely its dynamics and genetics. In the present paper, we propose a general framework to estimate the population mating patterns taking into account individual mating preferences and mating system, thus taking into account the inter- and intra-sexual interactions such as mate competition and mate choice. According to our results, mating patterns are not a direct reflection of mating preferences, but also depend upon the average sex ratio between individuals that are ready to mate at any given time (i.e., the Operational Sex Ratio, OSR). Therefore, mating patterns should be assessed not only in function of preferences, but also of OSR. It is then possible to distinguish three OSR regions: (1) the equilibrium OSR, where there is a predominance of assortative mating patterns due to differential access to mates (inter-sexual interactions); (2) the slightly biased OSR, where there is a high diversity of mating patterns and no clear predominance of inter- or intra-sexual interactions; and (3) the highly biased OSR where there is a predominance of mating patterns corresponding to single-sex uniform preferences and an increased influence of intra-sexual interactions. We hope that this approach may allow to further explore the interaction between OSR and mate choice, namely how such interaction may affect sexual selection and mate choice tactics.
Mathematical Models for the "Schmalhgausent Law"
Authors: Karev Georgy P. , Berezovskaya Faina S.
Published: August 2003

The empirical formula of growth (decrease) of biological objects, corresponding to polygonal line in double logarithmic scale is discussed. Leslie-type models producing solutions similar to some specific cases of this formula (including logistic-like curve) are studied. As an example, a model of tree stand self-thinning is derived and investigated; the model allows fitting empirical data with high accuracy.
Modeling and Analysis of the Spread of Carrier Dependent Infectious Diseases with Environmental Effects
Authors: Singh Shikha , Chandra Peeyush , Shukla J. B.
Published: August 2003

In this paper, SIS and SIRS models for carrier dependent infectious diseases with immigration are proposed and analyzed by considering effects of environmental and human population related factors which are conducive to the growth of carrier population. In the modeling process, the density of carrier population is governed by a general logistic model. Further, it is assumed that the growth rate per capita and the modified carrying capacity of carrier population increase as the human population density increases. In each case, it is shown that the spread of an infectious disease increases as the carrier population density increases and the disease becomes more endemic due to immigration.
Receptor-Based Models with Diffusion-Driven Instability for Pattern Formation in Hydra
Authors: Marciniak-Czochra Anna
Published: August 2003

The aim of this paper is to show under which conditions a receptor-based model can produce and regulate patterns. Such model is applied to the pattern formation and regulation in a fresh water polyp, hydra. The model is based on the idea that both head and foot formation could be controlled by receptor-ligand binding. Positional value is determined by the density of bound receptors. The model is defined in the form of reaction-diffusion equations coupled with ordinary differential equations. The objective is to check what minimal processes are sufficient to produce patterns in the framework of a diffusion-driven (Turing-type) instability. Three-variable (describing the dynamics of ligands, free and bound receptors) and four-variable models (including also an enzyme cleaving the ligand) are analyzed and compared. The minimal three-variable model takes into consideration the density of free receptors, bound receptors and ligands. In such model patterns can evolve only if self-enhancement of free receptors, i.e., a positive feedback loop between the production of new free receptors and their present density, is assumed. The final pattern strongly depends on initial conditions. In the four-variable model a diffusion-driven instability occurs without the assumption that free receptors stimulate their own synthesis. It is shown that gradient in the density of bound receptors occurs if there is also a second diffusible substance, an enzyme, which degrades ligands. Numerical simulations are done to illustrate the analysis. The four-variable model is able to capture some results from cutting experiments and reflects de novo pattern formation from dissociated cells.
Sufficient Conditions for Coordination of Coupled Nonlinear Biochemical Systems: Analysis of a Simple, Representative Example
Authors: Liu Junli , Marshall David F.
Published: August 2003

Under conditions of stress and environmental fluctuations, how do coupled biochemical systems maintain the balance of metabolic fluxes? Using a model derived from a representative glycolysis example, this work derives sufficient coordination conditions for guaranteeing the balance of metabolic fluxes in the coupled systems subjected to any fluctuations. For diffusion-like coupling, it is explicitly shown that the sufficient conditions are the linear summation of individual uncoupled systems. For this case, coupling strength is not a key factor affecting the balance of metabolic fluxes, although it may affect the emergence of certain dynamic patterns. When the sufficient coordination conditions are satisfied, coupled systems always settle onto stable finite states, independently of the nature (type, period or amplitude) of external signals. When they are not, external signals may force the stable states of coupled systems to lose their coordination, resulting in the coupled systems having no stable finite states which is inconsistent with most normal biological functions. Numerical simulations support the analytical results. The generalization of this result for other coupled nonlinear biochemical systems is discussed. Finally, the maintenance of such biological coordination is discussed in the context of genetic engineering and environmental fluctuations.
The Effects of Impulsive Toxicant Input on a Population in a Polluted Environment
Authors: Liu Bing , Chen Lansun , Zhang Yujuang
Published: August 2003

In this paper, we investigate a single species model in a polluted closed environment with pulse toxicant input at fixed moment. We show that the population is extinct when the impulsive period is less than some critical value, otherwise the population is permanent, and the permanent condition also assure that there exists a unique positive periodic solution which is globally asymptotically stable. By comparing with the continuous system, we show that pulse toxicant input cause a periodic behavior in our system and oscillation of the solution. From the biological point of view, it is easy to protect species by changing impulsive period of the exogenous input of toxicant, and toxicant input amount, etc. Further, the effects of environmental noise on the population are studied by using numerical methods.
Finite Element Calculation of Bone Remodeling in Orthodontics by Using Forces and Moments
Authors: Geiger Martin , Schneider Juergen , Sander Franz G.
Published: August 2003

Orthodontic appliances induce bone remodeling by acting as systems of forces and moments onto the crown of a tooth. These forces and moments should be within low physiological range to avoid resorptions. This is often realized by the use of superelastic wires or springs. For improving the design of these devices, we use the Finite Element Method (FEM) to simulate the behavior of teeth and devices. Great advantages were made in simulating the bone remodeling during the movement of a single tooth. Due to the lack of element types implementing hysteresis in the stress/strain graph, it is difficult to simulate the non-linear material properties of the superelastic wires made of NiTi-alloys. For this reason, we integrated the measurement of the devices into the calculation of the tooth movement. In this study we simulate the orthodontic long-term tooth movement of the canine retraction, using the new hybrid retraction spring.5 This spring allows a well-defined adjustment of the acting force system. The result of this study provides an example of how this approach can be used for future comparison of different orthodontic devices.
Biomechanical Multiphase Approaches in Soft Tissues
Authors: Meroi Emilio A. , Schrefler Bernhard A.
Published: August 2003

Presence of fluids drives mechanical response in biological, soft hydrated tissues. A multiphase approach has been developed to allow for a fully-comprehensive, physically based view of their history-dependent response in static and dynamics. The related formulation considers both geometric and material non-linearities. In the present work, the non-linear aspects related to fluid flows are investigated. Low speed flows of liquid phase depend on the permeability of the deforming solid matrix; permeability is naturally related to void ratio, but further dependences on other variables can be explicitly added. Two different biomechanical problems are considered and the results are presented here. In the first case, a human lumbar intervertebral segment is investigated in healthy and degenerate condition: higher permeability and lower mechanical properties of disc affect the capability to withstand an imposed constant compressive load in time. The permeability is related only to void ratio and is not affected by the overpressure that dissipates with time. The second case refers to the trabecular meshwork in the eye; this tissue has a rule in the regulation of outflow of the aqueous humour from the eye: a variation in permeability determines obviously a variation of internal ocular pressure to guarantee the assumed constant outflow, and on the other side, pressure changes affect permeability distribution and thus final pressure changes. This effect is particularly significant with glaucoma, and thus the increment of intraocular pressure can be related to a progressive reduction in tissue permeability. The modelling of this effect can be improved by introducing a proper permeability-pressure relationship in addition to the permeability-void ratio dependency.
Development of Magnetically Suspended Vaneless Centrifugal Blood Pump for Cardiopulmonary Bypass
Authors: Lee Y. , Chang J. K. , Lee S. H. , Jang J. U. , Lee K. B. , Lee H. W. , Sun K. , Kim H. M. , Kim J. , Yoo J. Y.
Published: August 2003

An ideal blood pump would provide sufficient flow rate against vessel pressure without hemolysis or thrombus formation. In preceding studies, it is known that non-contact operation by magnetic bearing system gives high mechanical reliability, low hemolysis and low thrombus formation. Therefore, in the present study a magnetically suspended vaneless centrifugal blood pump (MSVC-BP) has been developed for the use of cardiopulmonary bypass, in which the magnetic suspension centers the centrifugal rotor avoiding any contact. To predict the flow pattern in the pump head and to calculate shear stress on the rotor, numerical analysis has been performed using the TASCflow®. In vitro tests of hydrodynamic performance of the present pump have been carried out in mock circular system with glycerin solution, attaining a maximum flow rate of 12 L/min at 2200 rpm. In vivo tests of hemodynamic performance of the pump have also led to reasonable results for clinical usage.
Implications of Muscle Relative Position as a Co-Determinant of Isometric Muscle Force
Authors: Maas Huub , Yucesoy Can A. , Baan Guus C. , Huijing Peter A.
Published: August 2003

Force is transmitted from muscle fiber to bone via several pathways: (1) via the tendons (i.e. myotendinous force transmission), (2) via intermuscular connective tissue to adjacent muscles (i.e. intermuscular myofascial force transmission), (3) via structures other than muscles (i.e. extramuscular myofascial force transmission). In vivo, the position of a muscle relative to adjacent muscles changes due to differences in moment arm between synergists as well as due to the fact that some muscles span only one joint and other muscles more than one joint. The position of a muscle relative to non-muscular structures within a compartment is altered with each change of the length of the muscle.

The aim of this article is to describe recent experimental results, as well as some new experimental data, that have elucidated the role of muscle relative position on force transmission from muscle. Furthermore, relevant literature is discussed, taking into consideration these new insights of muscle functioning. It is concluded that the position of a muscle relative to surrounding tissues is a major co-determinant of isometric muscle force. For muscles operating within their in vivo context of connective tissue, such position effects should be taken into account.
Clinical Assessment of Postural Stability
Authors: Blaszczyk Janusz W. , Bacik Bogdan , Juras Grzegorz
Published: August 2003

One of the most important applications of postural sway analysis is the detection of such impairments to the motor system that would allow us to predict risk of falling. Force plate posturography is a commonly used clinical method for the evaluation of postural instability. The diagnostic value of postural sway represented here by oscillations of the center-of-foot pressure (COFP) is being questioned very often. These diagnostic problems result from the lack of an adequate and reliable method of sway analysis — a method that would present a clear connection between stability and quality of postural control. To gain better insight into this problem, the following experiments were done and some effective methods of sway analysis typically applied in conventional mechanics and electrical engineering are presented here. Quality of the postural stability was assessed using, in addition to standard parameters, spatial histograms, body transfer function, contour plots as well as the COFP fractal dimension. Such complex analysis allowed us to extract significant sway parameters that are relevant to postural instability. Analysis of the data revealed that spatial histogram has clear peak which maximum was sensitive to sensory conditions. Changes in the postural sway distributions have been confirmed by the increase of the COFP fractal dimension.
Using Hill-Type Muscle Models and EMG Data in a Forward Dynamic Analysis of Joint Moment
Authors: Heine Richard , Manal Kurt , Buchanan Thomas S.
Published: August 2003

There has been considerable interest in estimating muscle forces and joint moments from EMG signals, but most approaches have not been very successful. This is largely because robust models of muscle activation dynamics, Hill-type muscle contraction dynamics, and musculoskeletal geometry are generally not included. Here we present a model which includes these sub-models and we determine which model parameters are most important. The models abilities to predict joint moments about the human elbow during time-varying isometric tasks were examined. Inputs to the models were EMGs from eight muscles. Joint moment was the output, which was compared with the measured moment. Models varied in complexity, having up to 59 adjustable parameters. It was found that a seven adjustable parameter model could adequately estimate time-varying joint moments without substantial sacrifice in performance. The key parameters that were fit for each subject were two global gain factors, a time delay term, a non-linear EMG-force term, two muscle activation terms, and a term for skewing the length-tension curve with muscle activation. This approach offers advantages over optimization-based methods for estimating individual muscle forces. Most importantly, it accounts for the way muscles are activated, which makes it potentially powerful to evaluate patients with pathologies.
The Influence of Initial Stresses on Blood Vessel Mechanics
Authors: Nardinocchi Paola , Teresi Luciano
Published: August 2003

In order to account for the in vivo conditions of blood vessels, we investigate the mechanical behavior of a stressed tube-like membrane when small deformations are superimposed on large deformations: the latter simulate the stretches present in the in vivo arteries while the superimposed deformations account for the small — but essential for the blood propagation — deformations due to the pulsatile nature of the blood flow. Our aim is to discuss how a stress state influence the response of the vessel-blood system.
On Deciding Whether a Boolean Function is Constant or Not
Authors: Benatti Fabio , Marinatto Luca
Published: August 2003

We study the probability of making an error if, by querying an oracle a fixed number of times, we declare constant a randomly chosen n-bit Boolean function. We compare the classical and the quantum case, and we determine for how many oracle-queries k and for how many bits n one querying procedure is more efficient than the other.
Quantum Information and Special Relativity
Authors: Peres Asher , Terno Daniel R.
Published: August 2003

Relativistic effects affect nearly all notions of quantum information theory. The vacuum behaves as a noisy channel, even if the detectors are perfect. The standard definition of a reduced density matrix fails for photon polarization because the transversality condition behaves like a superselection rule. We can however define an effective reduced density matrix which corresponds to a restricted class of positive operator-valued measures. There are no pure photon qubits, and no exactly orthogonal qubit states. Reduced density matrices for the spin of massive particles are well-defined, but are not covariant under Lorentz transformations. The spin entropy is not a relativistic scalar and has no invariant meaning. The distinguishability of quantum signals and their entanglement depends on the relative motion of observers.
Quantum Seals
Authors: Bechmann-Pasquinucci H.
Published: August 2003

A quantum seal is a way of encoding a classical message into quantum states, so that everybody can read the message error-free, but at the same time the sender and all intended readers who have some prior knowledge of the quantum seal, can check if the seal has been broken and the message read. The verification is done without reading nor disturbing the sealed message.
Quantum Simulations of Physics Problems
Authors: Somma Rolando , Ortiz Gerardo , Knill Emanuel , Gubernatis James
Published: August 2003

If a large Quantum Computer (QC) existed today, what type of physical problems could we efficiently simulate on it that we could not efficiently simulate on a classical Turing machine? In this paper we argue that a QC could solve some relevant physical "questions" more efficiently. The existence of one-to-one mappings between different algebras of observables or between different Hilbert spaces allow us to represent and imitate any physical system by any other one (e.g. a bosonic system by a spin-1/2 system). We explain how these mappings can be performed, and we show quantum networks useful for the efficient evaluation of some physical properties, such as correlation functions and energy spectra.
Temperature Effect on Mølmer and Sørensen Model: A Two-Time Green's Function Method
Authors: Li Wei , Zhao Hongmin , Lin Jiatih
Published: August 2003

Using two-time Green's function we analyze the effect of temperature on the Mølmer and Sørensen (M–S) model of cold trapped ion quantum computer. A formula for the deviation of an internal state from its ground state is derived in the first-order approximation. The fluctuation of internal state caused by thermal motion is also discussed. The deviation of internal state when different trap parameters changes with the temperature are given too. The upper temperature limit for regular quantum computation is obtained and our result is in agreement with experiment.
Additivity of Entanglement of Formation of Two Three-Level-Antisymmetric States
Authors: Shimono Toshiyuki
Published: August 2003

Quantum entanglement is the quantum information processing resource. Thus it is of importance to understand how much of entanglement any particular quantum state has, and what kinds of laws entanglement and also the transformation between entanglement states are subjected to. Therefore, it is important to use proper measures of entanglement which have nice properties. One of the major candidates of such measures is "entanglement of formation", and whether this measurement is additive or not is an important open problem. We aim at certain states so-called "antisymmetric states" for which the additivity are not solved as far as we know, and show the additivity for two of them.
On Amplification of Light in the Continuous EPR State
Authors: Gorbachev V. N. , Trubilko A. I.
Published: August 2003

Two schemes of amplification of two-mode squeezed light in the continuous variable EPR-state are considered. They are based on the integrals of motion, which allow conserving quantum correlations whereas the power of each mode may increase. One of these schemes involves a three-photon parametric process in a nonlinear transparent medium and the other is a Raman type interaction of light with atomic ensemble. A generalization to multimode squeezed light is discussed.
Quantum States of Hierarchic Systems
Authors: Altaisky Mikhail V.
Published: August 2003

The density matrix formalism which is widely used in the theory of measurements, quantum computing, quantum description of chemical and biological systems always implies the averaging over all states of the environment. In practice this is impossible because the environment of the system is the complement of this system to the whole Universe and contains infinitely many degrees of freedom. A novel method of construction density matrix which implies the averaging only over the direct environment is proposed. The Hilbert space of state vectors for the hierarchic quantum systems is constructed.
The Semi-Quantum Computer
Authors: Vianna Reinaldo O. , Rabelo Wilson R. M. , Monken C. H.
Published: August 2003

We discuss the performance of the Search and Fourier Transform algorithms on a hybrid computer constituted of classical and quantum processors working together. We show that this semi-quantum computer would be an improvement over a pure classical architecture, no matter how few qubits are available and, therefore, it suggests an easier implementable technology than a pure quantum computer with arbitrary number of qubits.
Tutorial Notes on One-Party and Two-Party Gaussian States
Authors: Englert Berthold-Georg , Wódkiewicz Krzysztof
Published: August 2003

Gaussian states — or, more generally, Gaussian operators — play an important role in Quantum Optics and Quantum Information Science, both in discussions about conceptual issues and in practical applications. We describe, in a tutorial manner, a systematic operator method for first characterizing such states and then investigating their properties. The central numerical quantities are the covariance matrix that specifies the characteristic function of the state, and the closely related matrices associated with Wigner's and Glauber's phase space functions. For pedagogical reasons, we restrict the discussion to one-dimensional and two-dimensional Gaussian states, for which we provide illustrating and instructive examples.
Heparin Inhibition of Endothelial Cell Proliferation and Organization Is Dependent on Molecular Weight
Authors: Khorana Alok A. , Sahni Abha , Altland Owen D. , Francis Charles W.
Published: August 2003

Objective—

Studies have shown improved survival in cancer patients treated with low molecular weight heparins (LMWHs). Tumors depend on an expanding vasculature, and heparins may affect vessel growth and function. We investigated the effect of heparins differing in
M
r
on selected endothelial cell properties.

Methods and Results—

Human umbilical vein endothelial cells were cultured with fibroblast growth factor-2 and heparins differing in
M
r
. Cell proliferation was assessed by [
3
H]thymidine incorporation, and vascular organization was assessed by in vitro assays. Maximum inhibition of 94±2% was observed with 6-kDa LMWH, greater than the inhibition seen with unfractionated heparin (58±8%) or 3-kDa LMWH (60±9%,
P
=0.02 for both). No inhibition of proliferation was observed with heparin tetrasaccharide, octasaccharide, or pentasaccharide (fondaparinux). Three- and 6-kDa fractions decreased endothelial tube formation in Matrigel to 58±15% and 67±9% (
P
<0.05), respectively, of that with fibroblast growth factor-2, whereas no inhibition was observed with unfractionated heparin, tetrasaccharide, pentasaccharide, or octasaccharide. LMWH (6 kDa) also inhibited vessel formation in a placental explant.

Conclusions—

Heparin inhibition of endothelial cell proliferation and organization requires a chain length of >8 saccharide units, with maximal inhibition at
M
r
of 6 kDa. This
M
r
dependence differs from that required for anticoagulant activity.