An important feature of male fertility is the physiological priming of spermatozoa by a multifaceted process collectively referred to as capacitation. The end point of this evasive process is the hyperactivated spermatozoa capable of binding to terminal sugar residues on the egg's extracellular coat, the zona pellucida (ZP), and undergoing acrosomal exocytosis (i.e., induction of the acrosome reaction). The hydrolytic action of acrosomal enzymes released at the site of zona binding, along with the enhanced thrust generated by the hyperactivated beat (...) pattern of the bound spermatozoa, are important factors that regulate the penetration of ZP and fertilization of the egg. Despite many advances in identifying sperm components that promote capacitation, the mechanism underlying the calcium‐triggered process remains elusive. The purpose of this review article is to focus on new advances that have enhanced our understanding of in vivo/in vitro capacitation, a prerequisite event resulting from a dramatic modification and reorganization of the sperm membrane molecules. Special emphasis has been laid on accumulating evidence suggesting potential similarities between the sperm capacitation and early phases of calcium‐triggered membrane fusion (i.e., tethering and docking) during secretory and endocytotic pathways among eukaryotes. BioEssays 26:281–290, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

We discuss five kinds of representations of rationales and provide a formal account of how they can alter disputation. The formal model of disputation is derived from recent work in argument. The five kinds of rationales are compilation rationales, which can be represented without assuming domain-knowledge (such as utilities) beyond that normally required for argument. The principal thesis is that such rationales can be analyzed in a framework of argument not too different from what AI already has. The result is (...) a formal understanding of rationales, a partial taxonomy, and a foundation for computer programs that represent and reason with rationales.The five kinds of rationales are as follows: (c)ompression and (s)pecialization, which yield rules, and (d)isputation, which yields a decision. These are modeled as potentially changing the focus of the dispute. Then there are (f)it, a rationale for rules, and (r)esolution, a rationale for decisions. These cannot be modeled as simply; they force disputation to a meta-level, at least temporarily. (shrink)

Health care professionals often face moral dilemmas. Not dealing constructively with moral dilemmas can cause moral distress and can negatively affect the quality of care. Little research has been documented with methodologies meant to support professionals in care for the homeless in dealing with their dilemmas. Moral case deliberation is a method for systematic reflection on moral dilemmas and is increasingly being used as ethics support for professionals in various health-care domains. This study deals with the question: What is the (...) contribution of MCD in helping professionals in an institution for care for the homeless to deal with their moral dilemmas? A mixed-methods responsive evaluation design was used to answer the research question. Five teams of professionals from a Dutch care institution for the homeless participated in MCD three times. Professionals in care for the homeless value MCD positively. They report that MCD helped them to identify the moral dilemma/question, and that they learned from other people’s perspectives while reflecting and deliberating on the values at stake in the dilemma or moral question. They became aware of the moral dimension of moral dilemmas, of related norms and values, of other perspectives, and learned to formulate a moral standpoint. Some experienced the influence of MCD in the way they dealt with moral dilemmas in daily practice. Half of the professionals expect MCD will influence the way they deal with moral dilemmas in the future. Most of them were in favour of further implementation of MCD in their organization. (shrink)

Este artigo recorda os principais aspectos e motivações da Expedição Langsdorff, missão de reconhecimento do interior do Brasil iniciada em 1821, composta pelo cônsul russo barão Langsdorff, o pintor alemão Moritz Rugendas, Aimé-Adrien Taunay, Nicolas-Antoine Taunay, o polígrafo Hercules Florence e o especialista em mapas Néster G. Rubtsov. Busca diferenças entre esta expedição e iniciativas outras, a título de exemplo, as dos bandeirantes e jesuítas, bem como a expedição indigenista de Rondon, e propõe o aprofundamento das investiga­ções. Apresenta atributos resgatados (...) pela poesia brasileira contemporânea e elementos cons­titutivos da identidade cultural brasileira presentes na Expedição Langsdorff, os quais os auto­res sugerem ser relevantes para pesquisadores do tema e para a inserção do Brasil no contexto internacional político, diplomático e econômico nos tempos hodiernos. (shrink)

Error is protean, ubiquitous and crucial in scientific process. In this paper it is argued that understanding scientific process requires what is currently absent: an adaptable, context-sensitive functional role for error in science that naturally harnesses error identification and avoidance to positive, success-driven, science. This paper develops a new account of scientific process of this sort, error and success driving Self-Directed Anticipative Learning (SDAL) cycling, using a recent re-analysis of ape-language research as test example. The example shows the limitations of (...) other accounts of error, in particular Mayo’s (Error and the growth of experimental knowledge, 1996) error-statistical approach, and SDAL cycling shows how they can be fruitfully contextualised. (shrink)

Conditions are stated under which the "argument by analogy" is consistent with the principle of inverse probability. It is contended that the argument by analogy, in conjunction with a crucial test, has a legitimate place in scientific logic. As an example the astrophysical problem of solar granulation is discussed in detail and other examples are mentioned more briefly.

It is proposed that happiness be classified as a psychiatric disorder and be included in future editions of the major diagnostic manuals under the new name: major affective disorder, pleasant type. In a review of the relevant literature it is shown that happiness is statistically abnormal, consists of a discrete cluster of symptoms, is associated with a range of cognitive abnormalities, and probably reflects the abnormal functioning of the central nervous system. One possible objection to this proposal remains--that happiness is (...) not negatively valued. However, this objection is dismissed as scientifically irrelevant. (shrink)

Many physicists regard the flow of time as an illusion. There is an upper level flow of time, the phenomenon of past/present/future; and there is a lower level flow of time which is really a flow of events. Perceptual completion accounts for the lower level flow of time in a few ways: apparent movement; amodal completion; and dynamic change as exemplified by a newly described modal completion that we called happening. It acts like an illusory percept connecting discrete stimuli in (...) all sensory modalities. The past/present/future distinction cannot exist unless an object is perceived to be the same now as it is then. This cognition requires object persistence. Experiments with object persistence suggest the circumstances when that, too, is an illusory percept. The illusory percepts of object persistence and perceptual completion can account for the entire flow of time. Our findings and conclusions are congruent with a few time theories and cosmologies that suggest that the flow of time is an illusion. (shrink)

Background: Although fair distribution of healthcare services for older patients is an important challenge, qualitative research exploring clinicians’ considerations in clinical prioritisation within this field is scarce. Objectives: To explore how clinicians understand their professional role in clinical prioritisations in healthcare services for old patients. Design: A semi-structured interview-guide was employed to interview 45 clinicians working with older patients. The interviews were analysed qualitatively using hermeneutical content analysis. Participants: 20 physicians and 25 nurses working in public hospitals and nursing homes (...) in different parts of Norway. Results and interpretations: The clinicians struggle with not being able to attend to the comprehensive needs of older patients, and being unfaithful to professional ideals and expectations. There is a tendency towards lowering the standards and narrowing the role of the clinician. This is done in order to secure the vital needs of the patient, but is at the expense of good practice and holistic role modelling. Increased specialisation, advances and increase in medical interventions, economical incentives, organisational structures, and biomedical paradigms, may all contribute to a narrowing of the clinicians’ role. Conclusion: Distributing healthcare services in a fair way is generally not described as integral to the clinicians’ role in clinical prioritisations. If considerations of justice are not included in clinicians’ role, it is likely that others will shape major parts of their roles and responsibilities in clinical prioritisations. Fair distribution of healthcare services for older patients is possible only if clinicians accept responsibility in these questions. (shrink)

Distributive, procedural, and interactional justice are constructs that are increasingly being recognized as important factors that affect individual perceptions in the workplace environment. This paper presents a theoretical perspective that suggests that justice is perceived through a subjective lens that consists of individualized beliefs and proposes that cultural attributes and demographic characteristics play an integral part in determining the perception of justice. The distinctions between these three constructs are presented in context with the core beliefs of individual employees – affected (...) by a multitude of perceptual and demographic factors that we briefly identify herein. Based on the theoretical perspective, an instrument that measures the constructs of justice as perceived by individuals was developed. With a focus on justice within the business setting, hypotheses about attitudes related to justice were tested. Survey results confirm that the three constructs of justice are distinct but correlated. Significant differences were found in the perceptions of African-American respondents with regard to procedural justice. Although the empirical findings do not support all the hypotheses, this research highlights the need for further development of measures to assess the perception of justice in business settings and at an applied level, underscores the importance of recognizing cultural attributes and demographic characteristics in understanding how justice is perceived. (shrink)

What we perceive is the product of an intrinsic process and not part of external physical reality. This notion is consistent with the philosophical position of transcendental idealism but also agrees with physiological findings on the thalamocortical system. -Frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in thalamocortical networks, thereby transiently forming assemblies of coherent oscillations under constraints of sensory input and prefrontal attentional mechanisms. Perception and conscious experience may be based (...) on such assemblies and sensory input to thalamic nuclei plays merely a constraining role in their formation. In schizophrenia, the ability of sensory input to modulate self-organisation of thalamocortical activity may be generally reduced. If during arousal thalamocortical self-organisation is underconstrained by sensory input, then attentional mechanisms alone may determine the content of perception and hallucinations may arise. (shrink)

Gray takes an information-processing paradigm as his departure point, invoking a comparator as part of the system. He concludes that consciousness is to be found “in” the comparator but is unable to point to how the comparison takes place. Thus, the comparator turns out not to be an entity arising out of brain research per se, but out of the logic of the paradigm. In this way, Gray both reinvents dualism and remains trapped in the language game of his own (...) model – ending up dealing with the unknowable. (shrink)

A fetus may survive an intentional interference with its intrauterine environment (1) if gestational age is mistaken and the procedure of induced abortion does not kill the fetus, (2) if a change of heart takes place after abortifacient drugs are taken and the abortion does not proceed, and (3) if a high-multiple pregnancy is reduced to a singleton or a twin pregnancy to improve the likelihood that the remaining fetuses will reach viability. In each case, through cause or coincidence, an (...) abnormal baby may be born. The well-intentioned physician, responding to a patient's medical or psychological needs, risks a legal action in negligence or assault brought by a deformed surviving child. This hazard means that medical termination of pregnancy and selective pregnancy reduction put the practising physician at substantial risk in a way not usually associated with induced abortion. (shrink)

Societies are composed of groups that interact. Symbiotic groups are those in which agents complement each other in resources that they have in excess. Symbiotic groups are useful especially when the resources in an environment are distributed unevenly, because they enable agents to trade resources easily. However, for trading to happen successfully, agents in symbiotic groups need to cooperate, i.e., they should be willing to donate resources when appropriate. Similarly, if some agents in a symbiotic group are defectors, they should (...) be identified by others and eliminated from the group for the well-being of the remaining agents. Accordingly, we first study Edmonds’ tag-based model of symbiotic groups to understand the lifespan of symbiotic groups (e.g., why some groups live shorter than others). Then, we enhance Edmonds’ model by adding the capability of reciprocal interactions to agents, thus achieving a hybrid model. We capture reciprocity in three different models and study their effects on the elimination of defectors in symbiotic groups. Our experimental results show that the groups that are built with the proposed hybrid model can eliminate more defectors and earlier than tag-based models. Further, the hybrid approach can generate symbiotic groups more effectively and efficiently. (shrink)

The disappearance of the imperial biographies written by Marius Maximus is one of the more frustrating losses of Latin literature, for various reasons: the well-known testimony of Ammianus, the interest of Marius Maximus' attested contribution to the Historia Augusta, his importance, much in dispute, to the writer of that work, the lack of information on much of the period he covered, and, not least, the fascinating role assigned to him by modern scholars, remodelling a previous duality of sources, of bad (...) biographer in contrast to the good Ignotus. It has recently become common practice for the evidence of Ausonius' Caesares to be used in the search for this biographer. The suggestion goes back to a dissertation of F. della Corte in 1956/7, and was taken up in his edition of Ausonius' works by Pastorino, and discussed in the following year by Cazzaniga who, though uncertain about the dependence of Ausonius on Marius Maximus, does misleadingly assert ‘e certo che l'ultima epigramma tocca Elagabalo, che chiude la silloge’. More recently, della Corte has returned to the question and sketched a possible model for the growth of the whole extant collection of Ausonius' Caesares, on the basis of the manuscript tradition. The same volume contains a contribution to the question by S. d'Elia and includes, by a felicitous piece of editing, an extended footnote in which d'Elia is able to comment on the relevant part of della Corte's paper. Meanwhile, outside Italy, there have been parallel and independent developments. (shrink)

Perhaps the most remarkable feature of the works in which Ausonius of Bordeaux and Libanius of Antioch, writing within a few years of each other, recall their long and varied careers is that there is so little resemblance between them; the impressions given by these experienced and successful teachers could hardly be more disparate. The reader of Ausonius finds in his Protrepticus a familiar enough picture of the terrors of the schoolroom; his Professores offer at first sight a series of (...) bland commemorations apparently deficient in the interesting information which might be expected from such an archive. Libanius' many volumes, on the other hand, compared where appropriate with the Vitae Sophistarum of Eunapius, present a situation which is well summarised by the following sentences from Walden's work The Universities of Ancient Greece : ‘There was, among the sophists of the fourth century…little, if any, of that spirit of brotherhood… that usually exists in a community of scholars at the present day. Instead there were jealousy, spite and often unrelenting hatred’. This striking divergence between Ausonius and his Eastern counterparts is unlikely to reflect a basic difference between East and West, or between Latin- and Greek-speaking milieux; the complaints of Augustine about his problems in Africa and Rome warn against such a simple answer. When one adds the evidence provided seven centuries later by the Frenchman Peter Abelard, whose plaintive Historia Calamitatum — an account of the disasters he suffered, not those which he caused — is remarkably similar to the prickly self-justification of Libanius in its account of bitter scheming and almost military manoeuvres in the educational world, one is forced to consider whether the evidence of Ausonius is not a serious anomaly, and to seek an explanation. (shrink)