Fetoscopic myelomeningocoele closure: Is the scientific evidence enough to challenge the gold standard for prenatal surgery?

Since the completion of the Management of Myelomeningocoele Study, maternal-fetal surgery for spina bifida has become a valid option for expecting parents. More recently, multiple groups are exploring a minimally invasive approach and recent outcomes have addressed many of the initial concerns with this approach. Based on a previously published framework, we attempt to delineate the developmental stage of the surgical techniques. Furthermore, we discuss the barriers of performing randomized controlled trials comparing two surgical interventions and suggest that data collection through registries is an alternative method to gather high-grade evidence.     

Use of extant kinetic parameters to predict effluent concentrations of specific organic compounds at full-scale facilities.

To use the results of kinetic tests to predict effluent concentrations of specific contaminants in activated sludge systems, the fraction of the biomass that has an ability to degrade the test compound (i.e., competent biomass) must be estimated. A calibration procedure was developed to assess the competent biomass concentration because the chemical oxygen demand (COD) fraction tended to underestimate the degrading fraction for three of the four test compounds. Acetone, for instance, had a measured influent COD fraction of 0.08%, and the actual competent fraction was estimated to be 2.3%, based on the model calibration. Once the competent biomass fraction in the mixed liquor was determined, the extant kinetic parameters were subsequently used to predict activated sludge system performance. Predicted effluent concentrations were within 2, 5, and 16% of the average measured concentrations for acetone, linear alkylbenzene sulfonate, and furfural, respectively. Day-to-day predictions for these compounds were less accurate, possibly because of the non-steady-state nature of the activated sludge systems studied. The difference between the fraction of the influent COD contributed by the target compounds and the competent biomass fraction in the mixed liquor was found to be more significant when the target compound contributed less than 1% of the influent organic matter. The chemical structure of the target compound and chemical composition of the influent likely had an effect on the resulting competent biomass concentration. The total maximum growth rate, microX, was observed to be independent of the influent concentration of acetone and furfural, thus suggesting that the competent biomass concentration for these compounds was not affected by the changes in their influent concentrations. Consequently, a majority of competent biomass growth resulted from the degradation of other substrates, resulting in a competent biomass concentration significantly higher than predicted based on the influent COD fraction contributed by the test compound.     

气候变化对淡水珍珠蚌种群的威胁

引言 在过去的100年中,淡水珍珠蚌Margaritfera margaritifera(L.)的数量在地球北区范围内已经下降到被IUCN列为濒危品种[1].人们认为主要原因是严重的工业污染和农业(有机)污染,采珠渔民的过度开采,寄主鲑科鱼类的减少,以及由于水力发电和河流管理计划的实施所造成的自然河床栖息环境的退化[2].     

Evaluating the long-term metacommunity dynamics of tree hole mosquitoes

Four different conceptual models of metacommunities have been proposed, termed "patch dynamics," "species sorting", "mass effect", and "neutral". These models simplify thinking about metacommunities and improve our understanding of the role of spatial dynamics both in structuring communities and in determining local and regional diversity. We tested whether mosquito communities inhabiting water-filled tree holes in southeastern Florida, U.S.A., displayed any of the characteristics and dynamics predicted by the four models. The densities of the five most common species in 3-8 tree holes were monitored every two weeks during 1978-2003. We tested relationships between habitat variables and species densities, spatial synchrony, the presence of life history trade-offs, and species turnover. Dynamics showed strong elements of species sorting, but with considerable turnover, as predicted by the patch dynamics model. Consistent with patch dynamics, there was substantial asynchrony in dynamics for different tree holes, substantial species turnover in space and time, and an occupancy/colonization trade-off. Substantial correlations of density and occupancy with tree hole volume were consistent with the species-sorting model, but unlike this model, species did not have permanent refuges. No evidence of mass effects was found, and correlations between habitat variables and dynamics were inconsistent with neutral models. Our results did not match a single model and therefore caution against overly simplifying metacommunity dynamics by using one dynamical characteristic to select a particular metacommunity perspective.     

Deep distributions of oceanic cirripede larvae in the Sargasso Sea and surrounding North Atlantic Ocean

From deep ( 1000 m), multi-depth zooplankton samples taken in the Azores frontal region from November 1980 to June 1981, high numbers of the two larval forms ofLepas pectinata, the commonest lepadid cirripede in this area, were sampled. The nauplii and cyprid larvae are large and long-lived. Nauplii were sampled where they feed, in the upper 150 m, closely associated with the fluorescence maximum. The cyprids were mainly sampled between 300 and 400 m, with a sharp cut-off in numbers just below the distribution peak. This deep distribution is intriguing, as the cyprids, which were not migrating diurnally, are non-feeding. To complete their life cycle they must settle on floating debris at the surface, where very few were sampled. They are negatively buoyant and there is no apparent physical reason for this deep distribution. There was no obvious pattern of changes in individual length or length/dry weight distribution with depth, the population appeared homogeneous. There was also no accumulation of other zooplankton at the same depth, or evidence from gut contents of large carnivores that the distribution pattern was caused by selective predation. A close association exists betweenL. pectinata andSargassum spp. weed, the cyprids preferentially settling on small fragments of weathered weed, the supply of which may be enhanced after winter. During winter, the harsh environment at the surface of the northern Sargasso Sea may discourage cyprid settlement. The deep distribution may be an ontogenetic migration conferring some survival advantage and saving energy due to the lower temperature and oxygen levels at depth. If it is a behavioural mechanism, duration of the cyprid stage will be extended until a more clement time of year, allowing them to settle over a longer period. The cyprids of other species were also sampled at depth, so the phenomenon appears to be widespread. If subsequent research confirms these observations as an ontogenetic migration, our current understanding of the fouling behaviour of oceanic lepadid cirripedes would be considerably modified.     

The threat of climate change to freshwater pearl mussel populations

Changes in climate are occurring around the world and the effects on ecosystems will vary, depending on the extent and nature of these changes. In northern Europe, experts predict that annual rainfall will increase significantly, along with dramatic storm events and flooding in the next 50-100 years. Scotland is a stronghold of the endangered freshwater pearl mussel, Margaritifera margaritifera (L.), and a number of populations may be threatened. For example, large floods have been shown to adversely affect mussels, and although these stochastic events were historically rare, they may now be occurring more often as a result of climate change. Populations may also be affected by a number of other factors, including predicted changes in temperature, sea level, habitat availability, host fish stocks and human activity. In this paper, we explain how climate change may impact M. margaritifera and discuss the general implications for the conservation management of this species.     

The European Union Solidarity Fund

This paper examines the legitimacy, viability and efficiency of the European Union Solidarity Fund by asking whether the Fund meets its stated purpose of providing solidarity within the EU, whether it is sufficiently capitalized and if it promotes disaster risk reduction in Europe. In examining these questions, we make use of ADAM models of disaster risks throughout Europe. We conclude that the Solidarity Fund falls short on all three counts, and we suggest possible alternatives. Most far-reaching, we explore whether the EUSF could support insurance systems in Europe by, among other possible activities, capitalizing national public-private insurance programs and providing support for government risk transfer. This would leverage the Fund’s capital and would overcome barriers to the provision of private and public sector insurance in uncertain catastrophe markets. It would also make insurance more affordable to Europe’s most vulnerable communities. Finally, it would reduce the disincentives for risk reduction inherent in post-disaster assistance.