Twin–twin transfusion syndrome—possible roles for doppler ultrasound and amniocentesis

A 29-year-old woman was referred for suspicion of twin-twin transfusion syndrome (TTTS). Several ultrasonographic and neonatal criteria of TTTS were encountered in this twin pregnancy. The peculiar observations in this case were, firstly, the demonstration of superficial anastomosis by Doppler ultrasound and, secondly, that one single therapeutic amniocentesis could have been sufficient to partially correct the progression of the syndrome, as after amniocentesis it was no longer possible to demonstrate the vascular communication. This observation suggests that superficial anastomoses could also have a role in the genesis of TTTS. Their effect could be monitored by Doppler ultrasound and could be more easily corrected by therapeutic amniocentesis.     

Recurrent congenital toxoplasmosis in a woman with lupus erythematosus

We describe the case of a patient with systemic lupus erythematosus, treated by corticosteroids, who presented during two successive pregnancies with serological reactivation of toxoplasmosis associated with fetal lesions. The first infected fetus died in utero with signs of hydrops. The second fetus was treated in utero with a combination of sulfadoxine and pyrimethamine, administered to the mother, and is now well. The increasing number of immunocompromised pregnant patients with immunity to Toxoplasma gondii may lead to a higher risk of reactivation of maternal toxoplasmosis and congenital infection.     

Emotional exhaustion and job performance: The moderating roles of distributive justice and positive affect

In a field study among 241 shop assistants and their 59 supervisors in fashion chain stores in Mainland China and Hong Kong, we found a negative relationship between emotional exhaustion and four indicators of job performance (overall performance, emotional display, OCB‐O, and OCB‐I) when employees perceived high levels of distributive justice in the exchange relationship with the organization, whereas emotional exhaustion was unrelated to any of these performance types when employees perceived low levels of distributive justice. In addition, this negative two‐way interaction effect of emotional exhaustion by distributive justice on job performance was buffered when employees were high on positive affect and intensified when they were low on positive affect. We used the conservation of resources (COR) theory, the attribution model of justice, and the broaden‐and‐build theory of positive emotions to clarify and discuss the moderating roles of distributive justice and positive affect in the relationship between emotional exhaustion and job performance. Copyright © 2009 John Wiley & Sons, Ltd.     

A statistical test to detect vortices in the current fields of bodies of water

Vortices could play an important role in the occurrence of certain biological phenomena, such as the massive proliferation of harmful algae in bodies of water. Many measures exist to detect vortices in fluids, but little is known about the stochastic behavior of these quantities with data that contain statistical noise. Consequently they do not provide control over the probability of false positives and give little information about the risk of false negatives. Obtaining such control requires a statistical testing procedure. In this paper, we develop a test for vortices in random current fields using only the directions of the current observed at points on a regular grid. We construct a change-point test for spatially ordered angular data to detect the presence of a local vortex. A global vortex detection procedure based on this test is developed and applied to a data set from a lagoon located in the south of France. It is shown that this procedure can detect the presence of multiple vortices with good accuracy.     

Interannual variability of growth and reproduction in Bursera simaruba: the role of allometry and resource variability

Plants are expected to differentially allocate resources to reproduction, growth, and survival in order to maximize overall fitness. Life history theory predicts that the allocation of resources to reproduction should occur at the expense of vegetative growth. Although it is known that both organism size and resource availability can influence life history traits, few studies have addressed how size dependencies of growth and reproduction and variation in resource supply jointly affect the coupling between growth and reproduction. In order to understand the relationship between growth and reproduction in the context of resource variability, we utilize a long-term observational data set consisting of 670 individual trees over a 10-year period within a local population of Bursera simaruba (L.) Sarg. We (1) quantify the functional form and variability in the growth-reproduction relationship at the population and individual-tree level and (2) develop a theoretical framework to understand the allometric dependence of growth and reproduction. Our findings suggest that the differential responses of allometric growth and reproduction to resource availability, both between years and between microsites, underlie the apparent relationship between growth and reproduction. Finally, we offer an alternative approach for quantifying the relationship between growth and reproduction that accounts for variation in allometries.     

Body size,demography and foraging in a socially plastic sweat bee: a common garden experiment

Phenotypic plasticity may evolve when conditions vary temporally or spatially on a small enough scale. Plasticity is thought to play a central role in the early stages of evolutionary transitions, including major transitions such as those between non-sociality and sociality. The sweat bee Halictus rubicundus is of special interest in this respect, because it is socially plastic in the British Isles: Nests are social or non-social depending on the environment. However, sociality comprises a complex suite of inter-related traits. To further investigate social plasticity in H. rubicundus, we measured traits that are potentially integral to social phenotype at a northern site, where nests are non-social, and a southern site where nests can be social. We found that foundresses at non-social sites were smaller, produced offspring of a size more similar to themselves, initiated nesting later, and took longer to produce their first female offspring. They began provisioning earlier in the day, finished earlier, and collected more pollen loads. Common garden experiments suggested that these differences represent mainly plasticity, as expected for traits involved in the overall plastic social phenotype, with only limited evidence for fixed genetic differences in foraging. Conditions during overwintering did not have major effects on a foundress' subsequent behaviour.