Melanism, body condition and elevational distribution in the asp viper

Alternative morphotypes can confer important selective advantages in different habitats, whereas they can be penalized in other circumstances. In ectotherms, such as reptiles, the body colour can have direct effects on numerous aspects of their existence, such as thermoregulation or prey-predator interactions. Darker melanic individuals show lower skin reflectance and consequently heat up more rapidly and maintain optimal body temperatures more easily than lighter coloured individuals. As a consequence, melanistic individuals of diurnal species in cool areas may exhibit higher body condition, growth rate, survival and fecundity than lighter coloured individuals. Such advantages of dark coloration may be counterbalanced by a lower crypsis to predators and a decreased foraging efficiency. We investigated, in two montane populations of asp vipers Vipera aspis, the relationship between (1) colour polymorphism and body condition and length and (2) the coloration of individuals and their elevational distribution. We showed significant relationships between (1) the coloration, body condition and sex of individuals; (2) sexes and reproductive state and morph frequency; and (3) colour morphs that were distributed following an elevational gradient. Hence, colour polymorphism plays an important role in the ecology and evolution of the asp viper and is maintained through differential selective pressures.

National Alcohol Policy Ireland

The National Alcohol Policy is directed at reducing the prevalence of alcohol-related problems through an emphasis on moderation in alcohol consumption. The importance of a comprehensive alcohol policy was highlighted when Ireland endorsed the European Charter on Alcohol in December 1995 along with 48 other Member States of the WHO European Region. The alcohol-related problems are multidimensional, therefore the solutions most be multi-sectoral. This means that commitment to the National Alcohol Policy must be on the agenda of policy makers in all sectors and at all levels. An Alcohol Policy requires both environmental and individual strategies. There is strong evidence that policies which influence access to alcohol, control pricing through taxation and other public health measures, can have a positive impact on curtailing the health and social burden resulting from drinking (Edwards et al. 1994). However, a key to the effectiveness of such strategies is public support, enforcement and maintenance of the policies. In examining the rationale for a National Alcohol Policy a number of elements have been identified. Research is urgently required to identify attitudes and patterns of alcohol consumption across the population and within sub-groups of the population. Based on sound research, a sensible drinking message of Less is Better should form an educational empowerment programme with regional and local initiatives as a required and integral part of such a campaign. A health education programme in all schools should be part of the core curriculum. The availability and effectiveness of treatment services need to be established. Action to contain the availability of alcohol could be achieved by reducing the number of special exemptions for longer opening hours and controlling access to underage drinking by ID schemes nation-wide. The enforcement of drink driving legislation including random breath testing needs to be continued to reduce alcohol-related traffic accidents. All levels of the Drinks Industry should recognise that people have the right to be safeguarded from pressures to drink. Finally, a National Alcohol Policy could be co-ordinated by a wider National Substance Use Surveillance Unit.This resource was contributed by The National Documentation Centre on Drug Use.

Poverty, inequality and policy since 1997

This study examines the impact of policy on poverty and inequality in Britain since 1997This research shows what effect policies introduced since 1997 have had on reducing poverty and inequality. It offers a considered assessment of impacts over a decade:How did policies change, before 1997 and since then?What evidence is there of impacts on key outcomes?What gaps or problems remain or emerged?The study covers a range of subjects, including public attitudes to poverty and inequality, children and early years, education, health, employment, pensions, and migrants. It measures the extent of progress and also considers future direction and pressures, particularly in the light of recession and an ageing society.The research draws on extensive analysis of policy documents, analysis by government departments and research bodies, published statistics and evaluations, analysis of large-scale datasets, micro-simulation modelling and a long-running qualitative study with residents of low-income neighbourhoods.��

In-depth assessment delivers the verdict on the Government�۪s promise of a more equal society

An independent and detailed expert analysis of a decade of reforms (published 25 February) takes up the challenge made by Peter Mandelson in 1997 to “judge us after ten years of success in office. For one of the fruits of that success will be that Britain has become a more equal society.����”Commissioned by the Joseph Rowntree Foundation, the study, by a team led by LSE’s Centre for Analysis of Social Exclusion, shows sharp contrasts between different policy areas. Notable success stories include reductions in child and pensioner poverty, improved education outcomes for the poorest children and schools, and narrowing economic and other divides between deprived and other areas.But health inequalities continued to widen, gaps in incomes between the very top and very bottom grew, and poverty increased for working-age people without children.����In several policy areas there was a marked contrast between the first half of the New Labour period and the second half, when progress has slowed or even stalled.John Hills, one of the leaders of study, said, “Whether Britain has moved towards becoming a ‘more equal society’ depends on what you look at, and when. Where clear initiatives were taken, results followed. But as the growth of living standards slowed, even well before the recession, and public finances tightened, momentum seems to have been lost in several key areas.”Kitty Stewart added, “The government can take heart from achievements such as the reduction in child poverty up to 2004.����Recent data show that by then, child well-being in the UK had begun to move up the European league table from its dismal showing at the start of the decade that formed the basis of UNICEF’s damning 2007 report. But even with improved figures, Britain was still left with one of the highest rates of child poverty out of the 15 original EU members, and the latest figures show it had increased again by 2006/7.”����The study concludes that the decade from 1997 was favourable to an egalitarian agenda in several ways: the economy grew continuously; the government had large majorities and aspired to create more equality; and public attitudes surveys suggested pent-up demand for more public expenditure. But that environment now looks very uncertain, not just in the near future, but also in the longer term.����Fiscal pressures from an ageing society could further constrain resources available for redistribution, and public attitudes towards the benefit system have hardened while support for redistribution has declined.Hills added, “The 1980s and 1990s showed that hoping that rapid growth in living standards at the top would ‘trickle down’ to those at the bottom did not work.����The period since 1997 has shown that gains are possible through determined interventions, but they require intensive and continuous effort to be sustained.”JRF Chief Executive Julia Unwin added, “We know the potential impact the deepening recession will have on those already living in poverty. This book provides an important, timely and comprehensive assessment of where we are and what remains to be done.”

The use of biodiversity as source of new chemical entities against defined molecular targets for treatment of malaria, tuberculosis, and T-cell mediated diseases: a review

The modern approach to the development of new chemical entities against complex diseases, especially the neglected endemic diseases such as tuberculosis and malaria, is based on the use of defined molecular targets. Among the advantages, this approach allows (i) the search and identification of lead compounds with defined molecular mechanisms against a defined target (e.g. enzymes from defined pathways), (ii) the analysis of a great number of compounds with a favorable cost/benefit ratio, (iii) the development even in the initial stages of compounds with selective toxicity (the fundamental principle of chemotherapy), (iv) the evaluation of plant extracts as well as of pure substances. The current use of such technology, unfortunately, is concentrated in developed countries, especially in the big pharma. This fact contributes in a significant way to hamper the development of innovative new compounds to treat neglected diseases. The large biodiversity within the territory of Brazil puts the country in a strategic position to develop the rational and sustained exploration of new metabolites of therapeutic value. The extension of the country covers a wide range of climates, soil types, and altitudes, providing a unique set of selective pressures for the adaptation of plant life in these scenarios. Chemical diversity is also driven by these forces, in an attempt to best fit the plant communities to the particular abiotic stresses, fauna, and microbes that co-exist with them. Certain areas of vegetation (Amazonian Forest, Atlantic Forest, Araucaria Forest, Cerrado-Brazilian Savanna, and Caatinga) are rich in species and types of environments to be used to search for natural compounds active against tuberculosis, malaria, and chronic-degenerative diseases. The present review describes some strategies to search for natural compounds, whose choice can be based on ethnobotanical and chemotaxonomical studies, and screen for their ability to bind to immobilized drug targets and to inhibit their activities. Molecular cloning, gene knockout, protein expression and purification, N-terminal sequencing, and mass spectrometry are the methods of choice to provide homogeneous drug targets for immobilization by optimized chemical reactions. Plant extract preparations, fractionation of promising plant extracts, propagation protocols and definition of in planta studies to maximize product yield of plant species producing active compounds have to be performed to provide a continuing supply of bioactive materials. Chemical characterization of natural compounds, determination of mode of action by kinetics and other spectroscopic methods (MS, X-ray, NMR), as well as in vitro and in vivo biological assays, chemical derivatization, and structure-activity relationships have to be carried out to provide a thorough knowledge on which to base the search for natural compounds or their derivatives with biological activity.

Garnet growth in the metasediments of the Zermatt-Saas Fee zone (western alps)

The Zermatt-Saas Fee Zone (ZSZ) in the Western Alps consists of multiple slices of ultramafic, mafic and metasedimentary rocks. They represent the remnants of the Mesozoic Piemonte-Ligurian oceanic basin which was subducted to eclogite facies conditions with peak pressures and temperatures of up to 20-28 kbar and 550-630 °C, followed by a greenschist overprint during exhumation. Previous studies, emphasizing on isotopie geochronology and modeling of REE-behavior in garnets from mafic eclogites, suggest that the ZSZ is buildup of tectonic slices which underwent a protracted diachronous subduction followed by a rapid synchronous exhumation. In this study Rb/Sr geochronology is applied to phengite included in garnets from metasediments of two different slices of the ZSZ to date garnet growth. Inclusion ages for 2 metapelitic samples from the same locality from the first slice are 44.25 ± 0.48 Ma and 43.19 ± 0.32 Ma. Those are about 4 Ma older than the corresponding matrix mica ages of respectively 40.02 ± 0.13 Ma and 39.55 ± 0.25 Ma. The inclusion age for a third calcschist sample, collected from a second slice, is 40.58 ± 0.24 Ma and the matrix age is 39.8 ± 1.5 Ma. The results show that garnet effectively functioned as a shield, preventing a reset of the Rb/Sr isotopie clock in the included phengites to temperatures well above the closure of Sr in mica. The results are consistent with the results of former studies on the ZSZ using both Lu/Hf and Sm/Nd geochronology on mafic eclogites. They confirm that at least parts of the ZSZ underwent close to peak metamorphic HP conditions younger than 43 m.y. ago before being rapidly exhumed about 40 m.y. ago. Fluid infiltration in rocks of the second slice occurred likely close to the peak metamorphic conditions, resulting in rapid growth of garnets. Similar calcschists from the same slice contain two distinct types of porphyroblast garnets with indications of multiple growth pulses and resorption indicated by truncated chemical zoning patterns. In-situ oxygen isotope Sensitive High Resolution Ion Microprobe (SHRIMP) analyses along profiles on central sections of the garnets reveal variations of up to 5 %o in individual garnets. The complex compositional zoning and graphite inclusion patterns as well as the variations in oxygen isotopes correspond to growing under changing fluid composition conditions caused by external infiltrated fluids. The ultramafic and mafic rocks, which were subducted along with the sediments and form the volumetrically most important part of the ZSZ, are the likely source of those mainly aqueous fluids. - La Zone de Zermatt-Saas Fee (ZZS) est constituée de multiples écailles de roches ultramafiques, mafiques et méta-sédimentaires. Cette zone, qui affleure dans les Alpes occidentales, représente les restes du basin océanique Piémontais-Ligurien d'âge mésozoïque. Lors de la subduction de ce basin océanique à l'Eocène, les différentes roches composant le planché océanique ont atteint les conditions du faciès éclogitique avec des pressions et des températures maximales estimées entre 20 - 28 kbar et 550 - 630 °C respectivement, avant de subir une rétrogression au faciès schiste vert pendant l'exhumation. Différentes études antérieures combinant la géochronologie isotopique et la modélisation des mécanismes gouvernant l'incorporation des terres rares dans les grenats des éclogites mafiques, suggèrent que la ZZS ne correspond pas à une seule unité, mais est constituée de différentes écailles tectoniques qui ont subi une subduction prolongée et diachrone suivie d'une exhumation rapide et synchrone. Afin de tester cette hypothèse, j'ai daté, dans cette étude, des phengites incluses dans les grenats des méta-sédiments de deux différentes écailles tectoniques de la ZZS, afin de dater la croissance relative de ces grenats. Pour cela j'ai utilisé la méthode géochronologique basée sur la décroissance du Rb87 en Sr87. J'ai daté trois échantillons de deux différentes écailles. Les premiers deux échantillons proviennent de Triftji, au nord du Breithorn, d'une première écaille dont les méta-sédiments sont caractérisés par des bandes méta-pélitiques à grenat et des calcschistes. Le troisième échantillon a été collectionné au Riffelberg, dans une écaille dont les méta-sédiments sont essentiellement des calcschistes qui sont mélangés avec des roches mafiques et des serpentinites. Ce mélange se trouve au-dessus de la grande masse de serpentinites qui forment le Riffelhorn, le Trockenersteg et le Breithorn, et qui est connu sous le nom de la Zone de mélange de Riffelberg (Bearth, 1953). Les inclusions dans les grenats de deux échantillons méta-pélitiques de la première écaille sont datées à 44.25 ± 0.48 Ma et à 43.19 ± 0.32 Ma. Ces âges sont à peu près 4 Ma plus vieux que les âges obtenus sur les phengites provenant de la matrice de ces mêmes échantillons qui donnent des âges de 40.02 ± 0.13 Ma et 39.55 ± 0.25 Ma respectivement. Les inclusions de phengite dans les grenats appartenant à un calcschiste de la deuxième écaille ont un âge de 40.58 ± 0.24 Ma alors que les phengites de la matrice ont un âge de 39.8 ± 1.5 Ma. Pour expliquer ces différences d'âge entre les phengites incluses dans le grenat et les phengites provenant de la matrice, nous suggérons que la cristallisation de grenat ait permis d'isoler ces phengites et de les préserver de tous rééquilibrage lors de la suite du chemin métamorphique prograde, puis rétrograde. Ceci est particulièrement important pour expliquer l'absence de rééquilibrage des phengites dans des conditions de températures supérieures à la température de fermeture du système Rb/Sr pour les phengites. Les phengites en inclusions n'ayant pas pu être datées individuellement, nous interprétons l'âge de 44 Ma pour les inclusions de phengite comme un âge moyen pour l'incorporation de ces phengites dans le grenat. Ces résultats sont cohérents avec les résultats des études antérieures de la ZZS utilisant les systèmes isotopiques de Sm/Nd et Lu/Hf sur des eclogites mafiques. ils confirment qu'aux moins une partie de la ZZS a subi des conditions de pression et de température maximale il y a moins de 44 à 42 Ma avant d'être rapidement exhumée à des conditions métamorphiques du faciès schiste vert supérieur autour de 40 Ma. Cette étude détaillée des grenats a permis, également, de mettre en évidence le rôle des fluides durant le métamorphisme prograde. En effet, si tous les grenats montrent des puises de croissance et de résorption, on peut distinguer, dans différents calcschists provenant de la deuxième écaille, deux types distincts de porphyroblast de grenat en fonction de la présence ou non d'inclusions de graphite. Nous lions ces puises de croissances/résorptions ainsi que la présence ou l'absence de graphite en inclusion dans les grenats à l'infiltration de fluides dans le système, et ceci durant tous le chemin prograde mais plus particulièrement proche et éventuellement peu après du pic du métamorphisme comme le suggère l'âge de 40 Ma mesuré dans les inclusions de phengites de l'échantillon du Riffelberg. Des analyses in-situ d'isotopes d'oxygène réalisé à l'aide de la SHRIMP (Sensitive High Resolution Ion Microprobe) dans des coupes centrales des grenats indiquent des variations jusqu'à 5 %o au sein même d'un grenat. Les motifs de zonations chimiques et d'inclusions de graphite complexes, ainsi que les variations du δ180 correspondent à une croissance de grenat sous des conditions de fluides changeantes dues aux infiltrations de fluides externes. Nous lions l'origine de ces fluides aqueux aux unités ultramafiques et mafiques qui ont été subductés avec les méta-sédiments ; unités ultramafiques et mafiques qui forment la partie volumétrique la plus importante de la ZZS.

Three essays in Swiss corporate governance

This dissertation is a combination of three relatively independent chapters on the subject of corporate governance. Corporate governance is presently at the epicenter of the global financial crisis. The lack of regulation and the misalignment of objectives have greatly contributed to the major crisis we are now in. Most governance research has been conducted in the United States in a context of widely held corporations and great executive power. It does not reflect the variety of situations around the world and we question the validity of this model in other contexts. The aim of this dissertation is to look at other governance models, in particular the Swiss corporate governance not only from a practical point of view, but also from a multi-theoretical approach. Traditional corporate governance literature has focused on the Anglo-American model that mainly follows the agency theory (Jensen and Meckling, 1976) in a shareholder-manager context, and overlooked other approaches. We focus on three different aspects of corporate governance using three different theories. First, we look at the ownership type of various corporations, using the agency theory in a context where issues between shareholders predominate over the typical shareholder-manager relationship. Second, we explore the adoption process of several governance mechanisms that, due to changes in legislation, has taken place in Switzerland since 2002. We use the institutional theory (DiMaggio and Powell, 1983), in a context where the environmental pressures are particularly high. Finally, we spotlight the board of directors as a key element of the governance of publicly listed corporations. Particularly, we focus on the independence of the board of directors, using a combination of the agency and resource dependence theories (Pfeffer, 1972; Pfeffer and Salancik, 1978).

Saving Mothers' Lives 2006-2008

The eighth Report of the Confidential Enquiries into Maternal Deaths in the UK investigates the deaths of 261 women who died in the triennium 2006-08, from causes directly or indirectly related to pregnancy. The full Report is available for purchase or download from the Centre for Maternal and Child Enquiries (CMACE; www.cmace.org.uk). Although every maternal death is a tragedy, particularly where avoidable factors were identified by the Enquiry process, the overall picture is encouraging. The maternal death rate in the UK continues to decline despite increasing pressures on maternity services and a changing maternal population. For the first time there has been a reduction in the inequalities gap between women living in different socio-economic circumstances, and timely production of guidelines and tools appears to have helped clinical staff to deliver improved clinical care.

Evolution of foraging behaviour in response to chronic malnutrition in Drosophila melanogaster.

Chronic exposure to food of low quality may exert conflicting selection pressures on foraging behaviour. On the one hand, more active search behaviour may allow the animal to find patches with slightly better, or more, food; on the other hand, such active foraging is energetically costly, and thus may be opposed by selection for energetic efficiency. Here, we test these alternative hypotheses in Drosophila larvae. We show that populations which experimentally evolved improved tolerance to larval chronic malnutrition have shorter foraging path length than unselected control populations. A behavioural polymorphism in foraging path length (the rover-sitter polymorphism) exists in nature and is attributed to the foraging locus (for). We show that a sitter strain (for(s2)) survives better on the poor food than the rover strain (for(R)), confirming that the sitter foraging strategy is advantageous under malnutrition. Larvae of the selected and control populations did not differ in global for expression. However, a quantitative complementation test suggests that the for locus may have contributed to the adaptation to poor food in one of the selected populations, either through a change in for allele frequencies, or by interacting epistatically with alleles at other loci. Irrespective of its genetic basis, our results provide two independent lines of evidence that sitter-like foraging behaviour is favoured under chronic larval malnutrition.

Coadaptation and malaria control

Malaria emerges from a disequilibrium of the system 'human-plasmodium-mosquito' (HPM). If the equilibrium is maintained, malaria does not ensue and the result is asymptomatic plasmodium infection. The relationships among the components of the system involve coadaptive linkages that lead to equilibrium. A vast body of evidence supports this assumption, including the strategies involved in the relationships between plasmodium and human and mosquito immune systems, and the emergence of resistance of plasmodia to antimalarial drugs and of mosquitoes to insecticides. Coadaptive strategies for malaria control are based on the following principles: (1) the system HPM is composed of three highly complex and dynamic components, whose interplay involves coadaptive linkages that tend to maintain the equilibrium of the system; (2) human and mosquito immune systems play a central role in the coadaptive interplay with plasmodium, and hence, in the mainten-ance of the system's equilibrium; the under- or overfunction of human immune system may result in malaria and influence its severity; (3) coadaptation depends on genetic and epigenetic phenomena occurring at the interfaces of the components of the system, and may involve exchange of infectrons (genes or gene fragments) between the partners; (4) plasmodia and mosquitoes have been submitted to selective pressures, leading to adaptation, for an extremely long while and are, therefore, endowed with the capacity to circumvent both natural (immunity) and artificial (drugs, insecticides, vaccines) measures aiming at destroying them; (5) since malaria represents disequilibrium of the system HPM, its control should aim at maintaining or restoring this equilibrium; (6) the disequilibrium of integrated systems involves the disequilibrium of their components, therefore the maintenance or restoration of the system's equilibrium depend on the adoption of integrated and coordinated measures acting on all components, that means, panadaptive strategies. Coadaptive strategies for malaria control should consider that: (1) host immune response has to be induced, since without it, no coadaptation is attained; (2) the immune response has to be sustained and efficient enough to avoid plasmodium overgrowth; (3) the immune response should not destroy all parasites; (4) the immune response has to be well controlled in order to not harm the host. These conditions are mostly influenced by antimalarial drugs, and should also be taken into account for the development of coadaptive malaria vaccines.

Biogeography and evolution of Amazonian triatomines (Heteroptera: Reduviidae): implications for Chagas disease surveillance in humid forest ecoregions

An ecological-evolutionary classification of Amazonian triatomines is proposed based on a revision of their main contemporary biogeographical patterns. Truly Amazonian triatomines include the Rhodniini, the Cavernicolini, and perhaps Eratyrus and some Bolboderini. The tribe Rhodniini comprises two major lineages (pictipes and robustus). The former gave rise to trans-Andean (pallescens) and Amazonian (pictipes) species groups, while the latter diversified within Amazonia (robustus group) and radiated to neighbouring ecoregions (Orinoco, Cerrado-Caatinga-Chaco, and Atlantic Forest). Three widely distributed Panstrongylus species probably occupied Amazonia secondarily, while a few Triatoma species include Amazonian populations that occur only in the fringes of the region. T. maculata probably represents a vicariant subset isolated from its parental lineage in the Caatinga-Cerrado system when moist forests closed a dry trans-Amazonian corridor. These diverse Amazonian triatomines display different degrees of synanthropism, defining a behavioural gradient from household invasion by adult triatomines to the stable colonisation of artificial structures. Anthropogenic ecological disturbance (driven by deforestation) is probably crucial in the onset of the process, but the fact that only a small fraction of species effectively colonises artificial environments suggests a role for evolution at the end of the gradient. Domestic infestation foci are restricted to drier subregions within Amazonia; thus, populations adapted to extremely humid rainforest microclimates may have limited chances of successfully colonising the slightly drier artificial microenvironments. These observations suggest several research avenues, from the use of climate data to map risk areas to the assessment of the synanthropic potential of individual vector species.

Personality and melanin-based colouration traits in barn owls, tawny owl and kestrels

Individuals need to adapt to their local environment in order to survive. When selection pressures differ in local populations, polymorphism can evolve. Colour polymorphism is one of the most obvious polymorphisms since it is readily observable. Different sources of colouration exist, but melanin-based colouration is one of the most common in birds. The melanocortin system produces this colouration and because the melanocortin system has pleiotropic effects on behavioural and physiological traits, it is a good candidate to be an underlying mechanism to explain the maintenance of colour polymorphism. In this thesis I studied three different raptors which all display melanin-based colouration; barn owls (Tyto alba), tawny owls (Strix aluco) and Eurasian kestrels (Falco tinnunculus). The main question was if there was a relationship between melanin-based colouration and individual behavioural differences. The underlying hypothesis is that colour could be a signal of certain adaptive traits. Our goal was to find evolutionary explanations for the persistence of colour polymorphism. I found that nestling kestrels and barn owls differ in anti-predatory behaviour, with respect to their melanic colouration (chapters 1 and 2). Darker individuals show less reaction to human handling, but in kestrels aggression and colouration are related in opposite ways than in barn owls. More reddish barn owls travel greater distances in natal dispersal and this behaviour is repeatable between parents and same sex offspring (chapter 3). Dark reddish tawny owls defend their nests more intensely against intruders and appear to suffer less from nest predation (chapter 4). Finally I show that polymorphism in the Melanocortin 1 receptor gene (MC1R), which is strongly correlated with reddish colouration in the barn owl, is related to natal dispersal distance, providing a first indication for a genetic basis of the relation between this behaviour and colouration (chapter 5). My results demonstrate a clear link between melanin-based colouration and animal personality traits. I demonstrated this relation in three different species, which shows there is most likely a general underlying mechanism responsible. Different predation pressures might have shaped the reactions to predation, but also differences in sex-related colouration. Male-like and female-like colouration might signal more or less aggressive behaviour. Fluctuating environmental conditions might cause different individual strategies to produce equal reproductive success. The melanocortin system with its pleiotropic effects might be an underlying mechanism, as suggested by the results from the genetic polymorphism, the similar results found in these three species and by the similar relations reported in other species. This thesis demonstrates that colouration and individual differences are correlated and it provides the first glimpse of an underlying system. We can now conduct a more directed search for underlying mechanisms and evolutionary explanations with the use of quantitative genetic methods.

The demographic benefits of belligerence and bravery: defeated group repopulation or victorious group size expansion?

Intraspecific coalitional aggression between groups of individuals is a widespread trait in the animal world. It occurs in invertebrates and vertebrates, and is prevalent in humans. What are the conditions under which coalitional aggression evolves in natural populations? In this article, I develop a mathematical model delineating conditions where natural selection can favor the coevolution of belligerence and bravery between small-scale societies. Belligerence increases an actor's group probability of trying to conquer another group and bravery increase the actors's group probability of defeating an attacked group. The model takes into account two different types of demographic scenarios that may lead to the coevolution of belligerence and bravery. Under the first, the fitness benefits driving the coevolution of belligerence and bravery come through the repopulation of defeated groups by fission of victorious ones. Under the second demographic scenario, the fitness benefits come through a temporary increase in the local carrying capacity of victorious groups, after transfer of resources from defeated groups to victorious ones. The analysis of the model suggests that the selective pressures on belligerence and bravery are stronger when defeated groups can be repopulated by victorious ones. The analysis also suggests that, depending on the shape of the contest success function, costly bravery can evolve in groups of any size.

Vaporization behaviour and some thermodynamic properties of the Pd-In, Pd-Pb, Pd-Sn systems

In this study, the vaporization behaviour of solid Pd-rich phases in the Pd-Pb, Pd-In and Pd-Sn systems was investigated by Knudsen-effusion-cell coupled with mass-spectrometry. The Pb, Pd, In vapor pressures [no Sn(g) has been detected in the vapor of Pd-Sn system] were evaluated in the temperatures range 1190-1563 K from the ion intensities measured over two-phases regions. Thermodynamic quantities were derived from vapor pressure data. In particular, for the Pd-Sn binary, the intermediate phase Pd7Sn2, the existence of which has been recently proposed, has been studied here for the first time. Furthermore, preliminary thermochemical data are presented for the diatomic intermetallic molecules PdSn and PdPb, which have been for the first time identified in the vapors in equilibrium over liquid solutions of appropriate composition at higher temperatures (1935-2025 K). (C) 2000 Elsevier Science Ltd. All rights reserved.

Isolated office hypertension: a prehypertensive state?

OBJECTIVE AND METHOD: Isolated office hypertension, defined as hypertensive blood pressure values in a medical setting but normal self-measured or ambulatory-recorded blood pressures, is frequently encountered in clinical practice. Yet, whether this condition represents a transient state in the development of a sustained ambulatory hypertension is still unknown as no long-term analysis of the evolution of ambulatory blood pressure has been carried out in patients with isolated office hypertension. To evaluate whether such patients should be considered as truly normotensive or hypertensive, we have studied the long-term changes in office and ambulatory blood pressures in 81 patients in whom isolated office hypertension was observed between 1982 and 1988. RESULTS: After a 5-6 year follow-up, 60 of the 81 patients had a mean 12 h daytime ambulatory blood pressure greater than 140/90 mmHg, suggesting an evolution towards ambulatory hypertension. The development of hypertension could not be predicted on the basis of the follow-up office blood pressures as these tended to decrease during the follow-up period. CONCLUSIONS: The results of this study suggest that patients with isolated office hypertension should not be considered as truly normotensive individuals. Hence, these patients require a careful medical follow-up. Office blood pressure readings alone, however, do not appear to provide a good indicator of the long-term outcome of isolated office hypertension.