Monochorionic and dichorionic twin pregnancies discordant for fetal anencephaly: a systematic review of prenatal management options

The aim of this study was to evaluate the effect of selective feticide (SF) compared to expectant management (EM) on perinatal outcome in dichorionic and monochorionic twins discordant for anencephaly. For this purpose, we conducted a systematic review of literature and added ten unpublished cases. As a result, we found that in dichorionic twins, mean gestational age (GA) at birth in the SF group was 38.0 weeks versus 34.9 weeks (P = 0.0002). Mean birth weight was 2922 g in the SF group versus 2474 g (P = 0.03). In monochorionic twins, mean GA at birth was 35.2 weeks versus 32.7 weeks (P = 0.1). Mean birth weight was 2711 g versus 1667 g (P = 0.0001). We conclude that while SF does not reduce perinatal mortality, it does result in significantly longer gestations and higher birth weight, and appears to be the management of choice in dichorionic twins discordant for anencephaly. In monochorionic twins, SF also increases birth weight, but in view of the complexity of this group, no clear recommendations can be made. Copyright © 2008 John Wiley & Sons, Ltd.     

Communities of different plant diversity respond similarly to drought stress: experimental evidence from field non-weeded and greenhouse conditions

Accelerating rate of species loss has prompted researchers to study the role of species diversity in processes that control ecosystem functioning. Although negative impact of species loss has been documented, the evidence concerning its impact on ecosystem stability is still limited. Here, we studied the effects of declining species and functional diversity on plant community responses to drought in the field (open to weed colonization) and greenhouse conditions. Both species and functional diversity positively affected the average yields of field communities. However, this pattern was similar in both drought-stressed and control plots. No effect of diversity on community resistance, biomass recovery after drought and resilience was found because drought reduced biomass production similarly at each level of diversity by approximately 30?%. The use of dissimilarity (characterized by Euclidean distance) revealed higher variation under changing environments (drought-stressed vs. control) in more diverse communities compared to less species-rich assemblages. In the greenhouse experiment, the effect of species diversity affected community resistance, indicating that more diverse communities suffered more from drought than species-poor ones. We conclude that our study did not support the insurance hypothesis (stability properties of a community should increase with species richness) because species diversity had an equivocal effect on ecosystem resistance and resilience in an environment held under non-weeded practice, regardless of the positive relationship between sown species diversity and community biomass production. More species-rich communities were less resistant against drought-stressed conditions than species-poor ones grown in greenhouse conditions.     

The oral cone of Anomalocaris is not a classic ‘‘peytoia’’

The Cambro-Ordovician anomalocaridids are large ecdysozoans commonly regarded as ancestors of the arthropods and apex predators. Predation is indicated partly by the presence of an unusual “peytoia”-type oral cone, which is a tetraradial outer ring of 32 plates, four of which are enlarged and in perpendicular arrangement. This oral cone morphology was considered a highly consistent and defining characteristic of well-known Burgess Shale taxa. It is here shown that Anomalocaris has a different oral cone, with only three large plates and a variable number of smaller and medium plates. Its functional morphology suggests that suction, rather than biting, was used for food ingestion, and that anomalocaridids in general employed a range of different scavenging and predatory feeding strategies. Removing anomalocaridids from the position of highly specialized trilobite predators forces a reconsideration of the ecological structure of the earliest marine animal communities in the Cambrian.     

A method of approach to landscape stability. Part 2: Ecooptimization of experimental territorial landscape segment in Bohemian forest

The method of anthropoecological landscape stability (AELS) has been applied experimentally to a territorial unit, forming a closed watershed with more of less precisely defined material, energy, and population flows. This article presents data-driven results of monitoring and conclusions on optimizing features derived from two object-oriented expert systems—the FORELIS, giving heuristically optimal conditions for forest compositions on the site in the prevailing immission situation, and AGRILIS—the agricultural expert system having the scope of finding suitable forms of agriculture with respect to natural conditions and suitable actual production facilities. The results of the study fully confirmed the feasibility of applying expert systems to actual conditions, and no significant errors in the results of the expert systems compared to indications by monitoring have been disclosed.     

Mate fidelity of renesting pied flycatchers Ficedula hypoleuca in relation to characteristics of the pair mates

Summary After a nesting failure, individual pied flycatchers may renest with the same or a new partner. In a 2-year study, carried out in a homogeneous habitat, we removed the clutches of a total of 124 monogamous pairs to study mate fidelity. The chance of a male obtaining a new partner if the pair bond had been broken was very low, so it would be in a male's interest to retain his original mate. Females in good condition showed a greater tendency to break the pair bond, and moved longer distances for renesting, than females in poor condition. Females that had nested in the area in a previous year were more site-tenacious, though not significantly more faithful to their mates, than those that were nesting in the area for the first time. Males that succeeded in retaining their mate were characterized primarily by having black plumage, and males from which certain feathers had been removed (=handicapped) tended to lose their mates. Females preferred the same male characteristics when they chose their mates in early spring. Hence, the decision about mate fidelity is influenced by the condition of the female and the attractiveness of her mate. Some evidence was found that male parental quality was correlated with male attractiveness.     

Guidelines for Nordic building regulations regarding indoor air quality

A subcommittee of the Nordic Committee for Building Codes has released guidelines for building regulations regarding indoor air quality, especially concerning ventilation. The main features of the guidelines, such as acceptable outdoor air quality for ventilation and minimum outdoor air flows for dwellings and offices, are presented and discussed. Mechanical ventilation is, in principle, required in all buildings including dwellings, due to the requirement of a minimum outdoor air change of 0.5 h⁻¹ and the normal highly airtight nature of new buildings. The guidelines are a basis for designing energy-efficient buildings while maintaining an indoor air quality which provides acceptable comfort and does not impair health.