We used computer simulations to study the possible role of the dispersion of cellular coupling, refractoriness or both, in the mechanisms underlying cardiac arrhythmias. Local ischemia was first assumed to induce cell to cell dispersion of the coupling resistance (Case 1), refractory period (Case 2), or both of them (Case 3). Our numerical experiments based on the van Capelle and Durrer model showed that vortices could not be induced by cell to cell variations. With cellular properties dispersed in a patchy (...) way within the ischemic zone, a single activation wave could give rise to abnormal activities. This demonstrates the stability of the wave front under small inhomogeneities. Probabilities of reentry, estimated for the three cases cited above showed that a severe alteration of the coupling resistance may be an important factor in the genesis of reentry. Moreover, use of isochronal maps revealed that vortices were both stable and sustained with an alteration of the coupling alone or combined with a reduction of the action potential duration. Conversely, simulations with reduction of the refractoriness alone, inducing only transient patterns, could exhibit functionally determined reentries. (shrink)

In this work we deal with a general class of spatially distributed periodic SIS epidemic models with two time scales. We let susceptible and infected individuals migrate between patches with periodic time dependent migration rates. The existence of two time scales in the system allows to describe certain features of the asymptotic behavior of its solutions with the help of a less dimensional, aggregated, system. We derive global reproduction numbers governing the general spatially distributed nonautonomous system through the aggregated system. (...) We apply this result when the mass action law and the frequency dependent transmission law are considered. Comparing these global reproductive numbers to their non spatially distributed counterparts yields the following: adequate periodic migration rates allow global persistence or eradication of epidemics where locally, in absence of migrations, the contrary is expected. (shrink)

The excessive and unsustainable exploitation of our marine resources has led to the promotion of marine reserves as a fisheries management tool. Marine reserves, areas in which fishing is restricted or prohibited, can offer opportunities for the recovery of exploited stock and fishery enhancement. This study examines the impact of the creation of marine protected areas, from both economic and biological perspectives. The consequences of reserve establishment on the long-run equilibrium fish biomass and fishery catch levels are evaluated. We include (...) reserve size as control variable to maximize catch at equilibrium. A continuous time model is used to simulate the effects of reserve size on fishing catch. Fish movements between the sites is assumed to take place at a faster time scale than the variation of the stock and the change of the fleet size. We take advantage of these two time scales to derive a reduced model governing the dynamics of the total fish stock and the fishing effort. Simulation results suggest that the establishment of a protected marine reserve will always lead to an increase in total fish biomass, an optimal size of a marine reserve can achieve to maximize the catch at equilibrium. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:BOOK REVIEWS 479 Saint Thomas au XXe siecle: Actes du colloque du Centenaire de la "Revue thomiste." Paris: Saint-Paul, 1994. Pp. 475 (paper). In March of 1993 the Revue thomiste marked its centenary by sponsoring a three-day colloquium at the lnstitut Catholique of Toulouse on "St. Thomas in the 20th century." The commemoration resumed the following month with a conference at the University of Fribourg (Switzerland), site of the (...) journal's foundation. This volume assembles the papers presented at the Toulouse colloquium and a selection of those read in Fribourg. All of the contributions are in French. The volume opens with a letter (dated 11 March 1993) that His Holiness John-Paul II addressed to the Prior Provincial of the Toulouse Dominicans, under whose aegis the Revue thomiste is now published. The Pope pays tribute to the "lucid discernment" that has guided this journal in a "critical and constructive reflection on the major problems of our epoch, assuring it a place of choice in Catholic intellectual life" (p. 7). Next follows an editorial introduction by Serge-Thomas Bonino, O.P., who examines the pertinence of the Revue's motto vetera novis augere. Acknowledging that the Thomistic revival of this century has largely proven to be unsuccessful, to judge by the extent of its cultural impact, he concludes nevertheless that this failure may pave the way for an eventual renewal, on condition that the past achievements and deficiencies of Thomism come to be adequately understood. The present volume thus aims to assess the efforts of Francophone philosophers and theologians to advance the thought of Thomas Aquinas; it thereby provides us with a valuable status quaestionis, enabling Aquinas's contemporary disciples to measure better the challenge that lies before them. The first of the volume's three sections is devoted to historical studies on the Revue thomiste's role in the formation of contemporary Neo-Thomism and its contribution to some of the important theological controversies in the first half of this century. Francesco Baretta narrates the vicissitudes of the journal's inception and first years (1893-1905). Not until the establishment in 1907 of the Revue des sciences philosophiques et theologiques by members of the Dominican order's Paris province (the reasons that motivated the foundation of a rival journal are taken up by Andre Duval in a paper wholly devoted to this topic [pp. 96108 ]) did the Revue thomi~te come to be closely affiliated with the Toulouse province. Prior to this time it enjoyed the active collaboration of the order's three French provinces: Lyon, Paris, and Toulouse. Inspired by the recently promulgated Aeterni Patris (1879), the founders of the Revue thomiste sought to implement the encyclical's recommendation that the doctrine of Thomas Aquinas be brought into fruitful dialogue with modern science. Yet in so doing the Revue thomiste encountered serious obstacles, both theoretical and practical. Theoretically, the journal's chief collaborators were unable to recognize the originality of the hypothetico-deductive method and thus persisted 480 BOOK REVIEWS in thematizing modem science according to the epistemological categories of Aristotle's Posterior Analytics. Practically, they were unable (some exceptions aside) to enlist the support of contributors competent in both experimental science and scholastic thought. Thomism's engagement with modernity is taken up anew by Henry Donneaud, who charts the Revue thomiste's role in the nascent modernist crisis. During this period (1900-1908) the journal's rapprochement with the physical sciences attenuated, giving way to a preoccupation with modernism and its attendant controversies: the evolution of Catholic dogmas, the nature and role of apologetics, etc. Far from presenting a united front in the face of these theological developments, the principal collaborators of the Revue thomiste diverged in the fundamental orientation of their responses. Gradually, two very different Thomisms emerged: one, markedly conservative, refused any compromise with the new trends, condemning them in toto by appeal to a literalist, a-historical reading of the master; the other, progressive, sought to confront the modernists on their own terrain by drawing on the resources of a Thomistic doctrine open to amendment. After a period of internal strife the latter orientation became the more dominant of the two. The very... (shrink)

The introduction of novel diagnostic techniques in clinical domains such as genomics and radiology has led to a rich ethical debate on how to handle unsolicited findings that result from these innovations. Yet while unsolicited findings arise in both genomics and radiology, most of the relevant literature to date has tended to focus on only one of these domains. In this article, we synthesize and critically assess similarities and differences between “scanning the body” and “sequencing the genome” from an ethical (...) perspective. After briefly describing the novel diagnostic contexts leading to unsolicited findings, we synthesize and reflect on six core ethical issues that relate to both specialties: terminology; benefits and risks; autonomy; disclosure of unsolicited findings to children; uncertainty; and filters and routine screening. We identify ethical rationales that pertain to both fields and may contribute to more ethically sound policies. Considerations of preserving public trust and ensuring that people perceive healthcare policies as fair also support the need for a combined debate. (shrink)

Background As our society is ageing, nursing homes are finding it increasingly difficult to deal with an expanding population of patients with dementia and a decreasing workforce. A potential answer to this problem might lie in the use of technology. However, the use and application of surveillance technology in dementia care has led to considerable ethical debate among healthcare professionals and ethicists, with no clear consensus to date. Aim To explore how surveillance technology is viewed by care professionals and ethicists (...) working in the field, by investigating the ideal application of surveillance technology in the residential care of people with dementia. Methods Use was made of the concept mapping method, a computer-assisted procedure consisting of five steps: brainstorming, prioritising, clustering, processing by the computer and analysis. Various participants (ranging from ethicists to physicians and nurses) were invited on the basis of their professional background. Results The views generated are grouped into six categories ranging from the need for a right balance between freedom and security, to be beneficial and tailored to the resident, and clearly defined procedures to competent and caring personnel, active monitoring and clear normative guidance. The results are presented in the form of a graphic chart. Conclusions There appears to be an inherent duality in the views on using surveillance technology which is rooted in the moral conflict between safety and freedom. Elaboration of this ethical issue has proved to be very difficult. (shrink)

The aim of this work was to compare experimental investigations on effects of lidocaine, calcium and, BRL 34915 on reentries to simulated data obtained by use of a model of propagation based on the Huygens' constriction method already described in previous works. Calcium and lidocaine effects are investigated on anisotropic conduction conditions. In both cases, reduction in conduction velocities are observed. In lidocaine case, a refractory area is located along the longitudinal axis. In agreement with experimental electrical mapping, the simulations (...) show that the stabilization of reentrant excitation is mainly due to the existence of this refractory area around which the reentrant circuit can develop. The experimental study shows that BRL 34915 has both arrhythmogenic and antiarrhythmic effects. A detailed electrophysiological analysis has shown that drug infusion act on normal cardiac cells by decreasing the relative and absolute refractory period. BRL 34915 action is simulated by a decrease in the refractory period showing that the time frequency of the reentrant activity is increased and that the spatial size where the reentry is developing is becoming smaller. These two effects are arrhythmogenic, the simulated data being so in good agreement with the experimental ones. (shrink)

BackgroundHuntington’s disease has a poor prognosis. For HD patients in the Netherlands, one way of dealing with their poor prognosis is by drawing up an advance euthanasia directive. Little is known about the perspectives of HD patients on their AED.AimTo gain insight into patients’ views on and attitudes towards their AED, and changes over time.MethodsA longitudinal qualitative interview study using 1 to 6 semi-structured interviews over a period of maximum three years. Nine HD patients who either had an AED or (...) were thinking about drawing it up participated in this study.ResultsWe identified two themes that characterize patients’ perspectives on their AEDs: general character of the AED; uncertainty around their AED. Ad The conditions that the participants described in their AED were generally not very specific for the person. Mostly they were general notions of unbearable suffering. Familiarity with HD in the family could play a role in drawing up an AED. Ad Participants generally were aware of the tentative character of their AED and could have doubts concerning their own willingness or the willingness of others in the future. Sometimes these doubts were so great, that it prevented them from drawing up an AED. However, patients did not alter their AED during the follow-up period or changed in their view or attitude on their AED.ConclusionHD patients that draw up an AED usually describe general conditions for euthanasia and recognize that these conditions may change as the disease progresses. An AED or the wish to draw one up may be a good conversation starter for conversations about goals and preferences for future care. (shrink)

This is the second volume of analytical commentary on Wittgenstein's masterpiece, the Philosophical Investigations. Like the first, it consists of philosophical essays and critical exegesis. The six essays deal comprehensively with various themes in Wittgenstein''s philosophy: the relationship between his mathematics and his philosophy of mind; his conception of grammar and rules of grammar; the relation between a rule and what accords with a rule; the characterization of rule-following as mastery of a technique manifest in practice; his notion of a (...) form of life, and of agreement in definitions and judgements; a comprehensive investigation into his account of logical and mathematical necessity and other topics. (shrink)

This fourth and final volume of the monumental commentary on Wittgenstein's _Philosophical Investigations_ covers pp 428-693 of the book. Like the previous volumes, it consists of philosophical essays and exegesis.

This major new study by one of the most penetrating and persistent critics of philosophical and scientific orthodoxy, returns to Aristotle in order to examine the salient categories in terms of which we think about ourselves and our nature, and the distinctive forms of explanation we invoke to render ourselves intelligible to ourselves. The culmination of 40 years of thought on the philosophy of mind and the nature of the mankind Written by one of the world’s leading philosophers, the co-author (...) of the monumental 4 volume _Analytical Commentary on the Philosophical Investigations_ Uses broad categories, such as substance, causation, agency and power to examine how we think about ourselves and our nature Platonic and Aristotelian conceptions of human nature are sketched and contrasted Individual chapters clarify and provide an historical overview of a specific concept, then link the concept to ideas contained in other chapters. (shrink)

... 243-) INTRODUCTION §§243- constitute the eighth 'chapter' of the book. Its point of departure is a natural query with respect to the conclusion of the ...

This major study examines the most fundamental categories in terms of which we conceive of ourselves, critically surveying the concepts of substance, causation, agency, teleology, rationality, mind, body and person, and elaborating the conceptual fields in which they are embedded. The culmination of 40 years of thought on the philosophy of mind and the nature of the mankind Written by one of the world’s leading philosophers, the co-author of the monumental 4 volume _Analytical Commentary on the Philosophical Investigations_ Uses broad (...) categories, such as substance, causation, agency and power to examine how we think about ourselves and our nature Platonic and Aristotelian conceptions of human nature are sketched and contrasted Individual chapters clarify and provide an historical overview of a specific concept, then link the concept to ideas contained in other chapters. (shrink)

This major new study by one of the most penetrating and persistent critics of philosophical and scientific orthodoxy, returns to Aristotle in order to examine the salient categories in terms of which we think about ourselves and our nature, and the distinctive forms of explanation we invoke to render ourselves intelligible to ourselves. The culmination of 40 years of thought on the philosophy of mind and the nature of the mankind Written by one of the world’s leading philosophers, the co-author (...) of the monumental 4 volume _Analytical Commentary on the Philosophical Investigations_ Uses broad categories, such as substance, causation, agency and power to examine how we think about ourselves and our nature Platonic and Aristotelian conceptions of human nature are sketched and contrasted Individual chapters clarify and provide an historical overview of a specific concept, then link the concept to ideas contained in other chapters. (shrink)

The concept of normal is so familiar that it can be hard to imagine contemporary life without it. Yet the term entered everyday speech only in the mid-twentieth century. Before that, it was solely a scientific term used primarily in medicine to refer to a general state of health and the orderly function of organs. But beginning in the middle of the twentieth century, normal broke out of scientific usage, becoming less precise and coming to mean a balanced condition to (...) be maintained and an ideal to be achieved. In Normality, Peter Cryle and Elizabeth Stephens offer an intellectual and cultural history of what it means to be normal. They explore the history of how communities settle on any one definition of the norm, along the way analyzing a fascinating series of case studies in fields as remote as anatomy, statistics, criminal anthropology, sociology, and eugenics. Cryle and Stephens argue that since the idea of normality is so central to contemporary disability, gender, race, and sexuality studies, scholars in these fields must first have a better understanding of the context for normality. This pioneering book moves beyond binaries to explore for the first time what it does—and doesn’t—mean to be normal. (shrink)

This volume collects P. M. S. Hacker's papers on Wittgenstein and related themes written over the last decade. Hacker provides comparative studies of a range of topics--including Wittgenstein's philosophy of psychology, conception of grammar, and treatment of intentionality--and defends his own Wittgensteinian conception of philosophy.

This fourth and final volume of the monumental commentary on Wittgenstein's Philosophical Investigations covers pp 428-693 of the book. Like the previous volumes, it consists of philosophical essays and exegesis.

Incorporating significant editorial changes from earlier editions, the fourth edition of Ludwig Wittgenstein's _Philosophical Investigations_ is the definitive _en face_ German-English version of the most important work of 20th-century philosophy The extensively revised English translation incorporates many hundreds of changes to Anscombe’s original translation Footnoted remarks in the earlier editions have now been relocated in the text What was previously referred to as ‘Part 2’ is now republished as _Philosophy of Psychology – A Fragment_, and all the remarks in it (...) are numbered for ease of reference New detailed editorial endnotes explain decisions of translators and identify references and allusions in Wittgenstein's original text Now features new essays on the history of the _Philosophical Investigations_, and the problems of translating Wittgenstein’s text. (shrink)

P. M. S. Hacker 1. The ‘confusion of psychology’ On the concluding page of what is now called ‘Part II’ of the Investigations, Wittgenstein wrote.

Law, Morality and Society Essays in Honour of H.L.A Hart.

P.M.S. Hacker 1. _The problems of Intentionality_ The problems of intentionality have exercised philosophers since the dawn of their subject. In the last century they were brought afresh into the limelight by Brentano. Famously he remarked that.

This chapter contains section titled: Baker's New Conception Waismann and Wittgenstein Wittgenstein on the Psychoanalytic Analogy Wittgenstein's Methodology Reconsidered Wittgenstein and Ryle 1: Categorial Confusions Wittgenstein and Ryle 2: Logical Geography Baker's Wittgenstein.