DIMINISHING RETURNS? RISK AND THE DUTY TO CARE IN THE SARS EPIDEMIC

The seriousness of the risk that healthcare workers faced during SARS, and their response of service in the face of this risk, brings to light unrealistic assumptions about duty and risk that informed the debate on duty to care in the early years of HIV/AIDS. Duty to care is not based upon particular virtues of the health professions, but arises from social reflection on what response to an epidemic would be consistent with our values and our needs, recognizing our shared vulnerability to disease and death. Such reflection underwrites a strong duty of care, but one not to be borne solely by the altruism and heroism of individual healthcare workers.     

HOW DID LIFE BECOME SO DIVERSE? THE DYNAMICS OF DIVERSIFICATION ACCORDING TO THE FOSSIL RECORD AND MOLECULAR PHYLOGENETICS

Abstract: The long‐term diversification of life probably cannot be modelled as a simple equilibrial process: the time scales are too long, the potential for exploring new ecospace is too large and it is unlikely that ecological controls can act at global scales. The sum of many clade expansions and reductions, each of which happens according to its own dynamic, probably approximates more a damped exponential curve when translated into a global‐scale species diversification curve. Unfortunately, it is not possible to plot such a meaningful global‐scale species diversification curve through time, but curves at higher taxonomic levels have been produced. These curves are subject to the vagaries of the fossil record, but it is unlikely that the sources of error entirely overwhelm the biological signal. Clades radiate when the external and internal conditions are right: a new territory or ecospace becomes available, and the lineage has acquired a number of characters that open up a new diet or mode of life. Modern high levels of diversity in certain speciose clades may depend on such ancient opportunities taken. Dramatic climatic changes through the Quaternary must have driven extinctions and originations, but many species responded simply by moving to more favourable locations. Ecological communities appear to be no more than merely chance associations of species, but there may be real interactions among species. Ironically, high species diversity may lead to more speciation, not, as had been assumed, less: more species create more opportunities and selective pressures for other species to respond to, rather than capping diversity at a fixed equilibrium level. Studies from the scale of modern ecosystems to global long‐term patterns in the fossil record support a model for the exponential diversification of life, and one explanation for a pattern of exponential diversification is that as diversity increases, new forms become ever more refinements of existing forms. In a sense the world becomes increasingly divided into finer niche space. Organisms have a propensity to speciate freely, species richness within ecosystems appears to generate opportunities for more speciation, clades show all kinds of patterns from sluggish speciation rates and constant diversity through time to apparently explosive speciation, and there is no evidence that rapidly speciating clades have reached a limit, nor that they are driving other clades to extinction. A corollary of this view is that current biodiversity must be higher than it has ever been. Limits to infinite growth are clearly local, regional, and global turnover and extinction events, when climate change and physical catastrophes knock out species and whole clades, and push the rising exponential curve down a notch or two.     

“WE CAME TO TALK WITH THE PEOPLE BEHIND THE DISEASE:” COMMUNICATION AND CONTROL IN MEDICAL EDUCATION

To explore the ways in which biomedical culture responds to the new curricular addition of communication skills training, we observed activities related to the communication skills training of a class of 70 first-year medical students in an Israeli medical school during 2002–3. In addition, focus groups were conducted with medical students (n = 210) during 1998–2001. A gap was found between the rhetoric of “patient-centered communication” and “empathy” and the traditional concerns of medical authority, efficiency, and scientism. Communication skills and empathy training were appropriated into medical socialization by being reconstructed as clinical competence. Findings are further discussed in the context of medical professionalism, Israeli culture, service acting and service roles, and organizational learning.     

STUDIES ON THE FUNCTIONAL DEVELOPMENT OF ROHON-BEARD CELLS AND THEIR RELATION TO EARLY EMBRYONIC BEHAVIOUS

Based upon the previous paper in whichthe localization of Rohon-Beard cells in theneurula and their cranio-caudal appearancein later embryonic stages were reported,experiments were carried out with the em-bryos of Cynops orientalis,to study the func-tional development of Rohon-Beard cells andthe pathway of impulse transmission to evokethe early flexure—the earliest behaviour—ofthe embryo.     

THE QUICK AND THE DEAD? SPERM COMPETITION AND SEXUAL CONFLICT IN SEA

Our view of sperm competition is largely shaped by game-theoretic models based on external fertilizers. External fertilization is of particular interest as it is the ancestral mode of reproduction and as such, relevant to the evolution and maintenance of anisogamy (i.e., large eggs and tiny, numerous sperm). Current game-theoretic models have been invaluable in generating predictions of male responses to sperm competition in a range of internal fertilizers but these models are less relevant to marine broadcast spawners, the most common and archetypal external fertilizers. Broadcast spawners typically have incomplete fertilization due to sperm limitation and/or polyspermy (too many sperm), but the effects of incomplete (<100% fertilization rates) fertilization on game-theoretic predictions are unclear particular with regards to polyspermy. We show that incorporating the effects of sperm concentration on fertilization success changes the predictions of a classic game-theoretic model, dramatically reversing the relationship between sperm competition and the evolutionarily stable sperm release strategy. Furthermore, our results suggest that male and female broadcast spawners are likely to be in conflict at both ends of the sperm environment continuum rather than only in conditions of excess sperm as previously thought. Across the majority of the parameter space we explored, males release either too little to too much sperm for females to achieve complete fertilization. This conflict could result in a coevolutionary race that may have led to the evolution of internal fertilization in marine organisms.