Sex, money, and premarital partnerships in southern Malawi

In this paper, I argue two main points. First, in premarital, sexual partnerships in rural Malawi, the purpose of money exchange extends beyond the alleviation of female partners' economic constraints, and, second, by clarifying this broader purpose, it becomes possible to recognize where women exert control over their own sexual selves. These findings come from field observations and a rich set of in-depth interviews (N=54), bolstered on occasion by survey data, conducted with young women and men, aged 15-24 years, in the Balaka district in the southern region of the country. This research demonstrates that, contrary to typical expectations, money and gift transfers in sexual partnerships are part and parcel of the courting practices of young Malawian women and men. Transfers are as much about the expression of love and commitment as they are about meeting the financial needs of women or the acquisition of sex for men. Using narrative information to shed light on the semiotics of the sex-money link, these findings from Malawi offer a new perspective that broadens usual interpretations of transactional sex, the understanding of which is critical in fighting AIDS.     

Chiral biphenyl diphosphines for asymmetric catalysis: stereoelectronic design and industrial perspectives

Two original chiral diphosphines, SYNPHOS and DIFLUORPHOS, have been synthesized on multigram scales. Their steric and electronic profiles have been established in comparison with the commonly used 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl and 6,6'-dimethoxy-2,2'-bis(diphenylphosphino)-1,1'-biphenyl ligands. A screening study of the four ligands in Ru(II)-catalyzed asymmetric hydrogenation of prochiral ketones and olefins has been performed. It revealed that the stereoelectronic features of the ligand and the substrate deeply influenced the enantioselectivities obtained in asymmetric hydrogenation, SYNPHOS and DIFLUORPHOS being fully complementary in terms of enantioselectivity for this reaction.     

Insulin stimulates the biosynthesis of chiro-inositol-containing phospholipids in a rat fibroblast line expressing the human insulin receptor.

HIRc-B cells (rat fibroblasts expressing the human insulin receptor) were incubated with myo-[3H]inositol for 48 hr, and the biosynthesis of chiro-[3H]inositol was investigated in the absence and presence of insulin following a time course up to 60 min. After phase separation, treatment with insulin for 15 min caused a 2.2-fold increase in the specific radioactivity of chiro-[3H]inositol-containing phospholipids in contrast to a 1.2-fold increase in the specific radioactivity of myo-[3H]inositol-containing phospholipids. No insulin-mediated change in the specific radioactivity was observed in the inositol phosphates or free inositols. Further detailed analysis of individual [3H]inositol-containing phospholipids demonstrated marked increases in specific activity of the chiro-[3H]inositol phospholipids after 15 min of incubation with insulin: phosphatidylinositol 4-phosphate and 4,5-bisphosphate, 4.2-fold; lysophosphatidylinositol, 1.5-fold; phosphatidylinositol, 3.2-fold. In contrast, myo-[3H]inositol-containing phospholipids demonstrated relatively small increases (1.1- to 1.4-fold) after 5 min of incubation with insulin. These findings indicate that insulin stimulates de novo synthesis of chiro-inositol-containing phospholipids at the inositol phospholipid level.     

From the Cover: Parasitism alters three power laws of scaling in a metazoan community: Taylor’s law,density-mass allometry,and variance-mass allometry

How do the lifestyles (free-living unparasitized, free-living parasitized, and parasitic) of animal species affect major ecological power-law relationships? We investigated this question in metazoan communities in lakes of Otago, New Zealand. In 13,752 samples comprising 1,037,058 organisms, we found that species of different lifestyles differed in taxonomic distribution and body mass and were well described by three power laws: a spatial Taylor’s law (the spatial variance in population density was a power-law function of the spatial mean population density); density-mass allometry (the spatial mean population density was a power-law function of mean body mass); and variance-mass allometry (the spatial variance in population density was a power-law function of mean body mass). To our knowledge, this constitutes the first empirical confirmation of variance-mass allometry for any animal community. We found that the parameter values of all three relationships differed for species with different lifestyles in the same communities. Taylor''s law and density-mass allometry accurately predicted the form and parameter values of variance-mass allometry. We conclude that species of different lifestyles in these metazoan communities obeyed the same major ecological power-law relationships but did so with parameters specific to each lifestyle, probably reflecting differences among lifestyles in population dynamics and spatial distribution.Variation in population density has long been a central topic in ecology (e.g., ref. 1). Taylor’s law (TL) (2, 3) is a pattern of variation that has been widely verified for population density in basic and applied ecology and for other quantities in other fields. In its ecological interpretations, TL asserts that, in multiple sets of populations, the sample variance in population density within each set is proportional to a power (usually positive) of the sample mean population density within that set. We specify TL in greater detail below.Morand and Guégan (4) showed that TL described well the variations of abundance per host in 828 populations of parasitic nematodes from 66 terrestrial mammalian species. Morand and Krasnov (5) reviewed examples of TL in parasitology and epidemiology and interpreted the exponent of the TL power law in terms of the aggregation of parasites and epidemiological dynamics. These studies used the number of individual parasites per individual host as the measure of population density. Following a suggestion of Taylor (2), these studies interpreted the exponent of the power-law relationship of variance of population density to mean of population density as an index of parasite aggregation among hosts. A purely random distribution of parasites per host leads to a Poisson distribution, which gives a TL exponent equal to 1 as the mean population density varies. A TL exponent greater than 1 reflects greater heterogeneity in numbers of individuals per host than expected from a purely random distribution. More importantly, the TL exponent may also be used to assess the strength of parasite population regulation via processes such as interspecific competition or vaccination, and may distinguish between epidemic and endemic infections (5–7).Here we ask how three lifestyles (free-living unparasitized, free-living parasitized, and parasitic) of animal species affect major ecological power-law relationships, including TL, using new data on all metazoans from the littoral zone of four lakes in coastal and central Otago, South Island, New Zealand. Unlike previous studies of TL in parasitology, we measured the population density of parasites as the number of individuals per square meter of habitat, not per individual host. Additionally, unlike previous studies, in addition to quantifying the population density of parasitic species (separately for each life stage), we quantified the population density of the free-living parasitized species and of the free-living unparasitized species in the same habitat. Contrasting TL and other power-law relationships among organisms with different lifestyles can reveal differences in the degree to which spatial heterogeneity in their abundance is regulated.Using these data, we tested the validity of TL for metazoans of each lifestyle in the same habitat. Intuitively, it seemed plausible, and we investigated the hypothesis, that the interactions of free-living parasitized species and parasites added variability to the population dynamics of species of both lifestyles compared with free-living unparasitized species. This qualitative argument led us to expect larger values of the exponent of TL for free-living parasitized species and parasites compared with the exponent of TL for free-living unparasitized species.In addition to testing TL and the effects of lifestyle on the parameters of TL, we examined the allometric relationship between mean population density and mean body mass (density-mass allometry, or DMA). Marquet et al. (8) and Cohen et al. (9) independently showed theoretically that TL and DMA combine to predict the form and parameters of an allometric relationship between the variance of population density and mean body mass (variance-mass allometry, or VMA). (The details of these predictions are in SI Appendix.) We tested and verified all three relations empirically for each lifestyle in the same habitat. The parameter values of all three relationships depended on lifestyle.Although DMA has been very widely confirmed for a great variety of organisms (e.g., refs. 10–18), including parasitic nematodes (19) and other parasites (20), VMA has previously been confirmed empirically only for congeneric trees (Quercus spp.) in a temperate forest (9). These new data permitted us to verify the predicted VMA empirically, to our knowledge for the first time for any animals and for the first time for all metazoans in a local community. Empirical confirmation of VMA for all metazoans in a local community makes it possible to use average body mass to predict the variability of population densities of different species, in addition to predicting the mean population density from DMA. This variability bears on risks of extinction, population outbreaks, and epidemics. The ability to predict this variability from a factor as easily measured as average body mass could be valuable for economically important species.     

An unusual mid term complication of coronary rupture

A 55-year-old man was admitted with a four-month history of lethargy, dyspnea and ascites. An idiopathic liver cirrhosis was suspected to be responsible for these symptoms and for elevated hepatic enzymes on blood tests. A few months before he had an angioplasty on the left anterior descending artery for an acute coronary syndrome (ACS). The intervention was complicated by coronary perforation which required the implantation of a polytetrafluoroethylene-covered (PTFE) stent to seal the rupture. On admission, pressure measurements during cardiac catheterism revealed a typical right ventricular dip-plateau consistent with the diagnosis of constrictive pericarditis (CP). Magnetic resonance imaging (RMI) showed localized pericardial thickening next to the right ventricle. We suspect hemopericardium, due to coronary perforation, is responsible for constrictive pericarditis. This mid-term complication of coronary rupture has not been reported before and should be suspected in this particular clinical setting.