Altered levels of insulin-like growth factor binding protein proteases in preeclampsia and intrauterine growth restriction

Intrauterine growth restriction (IUGR) and preeclampsia (PE) are leading causes of perinatal and maternal morbidity and mortality. Many studies have found association between low levels of insulin-like growth factor binding protein (IGFBP) proteases in the first trimester maternal circulation and the risk of subsequent development of PE and/or IUGR. These results are generally interpreted to reflect decreased production of the proteases by the placenta, leading to reduced proteolysis of IGFBPs and lower free levels of insulin-like growth factor (IGF), resulting in diminished feto-placental development. However, the association between low circulating levels of placental proteins early in pregnancy and the subsequent development of IUGR and/or PE could be due to low exchange in the placenta and not due to reduced production. In contrast, late in pregnancy, the circulating levels of these proteins and their expression in the placenta are often elevated in PE, which may reflect upregulation to compensate for abnormal placental development, that is an adaptive mechanism to increase IGFBP proteolysis, increase local IGF levels and promote feto-placental growth. Further research into the biological mechanisms underlying these associations will aid the identification of high-risk pregnancies and the development of therapeutic targets for diseases for which there are presently no preventative measures. Copyright © 2010 John Wiley & Sons, Ltd.     

The social network structure of a wild meerkat population: 2. Intragroup interactions

Knowledge of the structure of networks of social interactions is important for understanding the evolution of cooperation, transmission of disease, and patterns of social learning, yet little is known of how environmental, ecological, or behavioural factors relate to such structures within groups. We observed grooming, dominance, and foraging competition interactions in eight groups of wild meerkats (Suricata suricatta) and constructed interaction networks for each behaviour. We investigated relationships between networks for different social interactions and explored how group attributes (size and sex ratio), individual attributes (tenure of dominants), and ecological factors (ectoparasite load) are related to variation in network structure. Network structures varied within a group according to interaction type. Further, network structure varied predictably with group attributes, individual attributes, and ecological factors. Networks became less dense as group size increased suggesting that individuals were limited in their number of partners. Groups with more established dominant females were more egalitarian in their grooming and foraging competition interactions, but more despotic in their dominance interactions. The distribution of individuals receiving grooming became more skewed at higher parasite loads, but more equitable at low parasite loads. We conclude that the pattern of interactions between members of meerkat groups is not consistent between groups but instead depends on general attributes of the group, the influence of specific individuals within the group, and ecological factors acting on group members. We suggest that the variation observed in interaction patterns between members of meerkat groups may have fitness consequences both for individual group members and the group itself.     

A framework for definition of logical scenarios for safety assurance of automated driving

Abstract

Objective: In order to introduce automated vehicles on public roads, it is necessary to ensure that these vehicles are safe to operate in traffic. One challenge is to prove that all physically possible variations of situations can be handled safely within the operational design domain of the vehicle. A promising approach to handling the set of possible situations is to identify a manageable number of logical scenarios, which provide an abstraction for object properties and behavior within the situations. These can then be transferred into concrete scenarios defining all parameters necessary to reproduce the situation in different test environments.

Methods: This article proposes a framework for defining safety-relevant scenarios based on the potential collision between the subject vehicle and a challenging object, which forces the subject vehicle to depart from its planned course of action to avoid a collision. This allows defining only safety-relevant scenarios, which can directly be related to accident classification. The first criterion for defining a scenario is the area of the subject vehicle with which the object would collide. As a second criterion, 8 different positions around the subject vehicle are considered. To account for other relevant objects in the scenario, factors that influence the challenge for the subject vehicle can be added to the scenario. These are grouped as action constraints, dynamic occlusions, and causal chains.

Results: By applying the proposed systematics, a catalog of base scenarios for a vehicle traveling on controlled-access highways has been generated, which can directly be linked to parameters in accident classification. The catalog serves as a basis for scenario classification within the PEGASUS project.

Conclusions: Defining a limited number of safety-relevant scenarios helps to realize a systematic safety assurance process for automated vehicles. Scenarios are defined based on the point of the potential collision of a challenging object with the subject vehicle and its initial position. This approach allows defining scenarios for different environments and different driving states of the subject vehicle using the same mechanisms. A next step is the generation of logical scenarios for other driving states of the subject vehicle and for other traffic environments.     

Estimating rainforest biomass stocks and carbon loss from deforestation and degradation in Papua New Guinea 1972–2002: Best estimates,uncertainties and research needs

Reduction of carbon emissions from tropical deforestation and forest degradation is being considered a cost-effective way of mitigating the impacts of global warming. If such reductions are to be implemented, accurate and repeatable measurements of forest cover change and biomass will be required. In Papua New Guinea (PNG), which has one of the world's largest remaining areas of tropical forest, we used the best available data to estimate rainforest carbon stocks, and emissions from deforestation and degradation. We collated all available PNG field measurements which could be used to estimate carbon stocks in logged and unlogged forest. We extrapolated these plot-level estimates across the forested landscape using high-resolution forest mapping. We found the best estimate of forest carbon stocks contained in logged and unlogged forest in 2002 to be 4770 Mt (±13%). Our best estimate of gross forest carbon released through deforestation and degradation between 1972 and 2002 was 1178 Mt (±18%). By applying a long-term forest change model, we estimated that the carbon loss resulting from deforestation and degradation in 2001 was 53 Mt (±18%), rising from 24 Mt (±15%) in 1972. Forty-one percent of 2001 emissions resulted from logging, rising from 21% in 1972. Reducing emissions from logging is therefore a priority for PNG. The large uncertainty in our estimates of carbon stocks and fluxes is primarily due to the dearth of field measurements in both logged and unlogged forest, and the lack of PNG logging damage studies. Research priorities for PNG to increase the accuracy of forest carbon stock assessments are the collection of field measurements in unlogged forest and more spatially explicit logging damage studies.     

Employment commitment as a moderator of the maternal employment status/child behavior relationship

Research findings suggest that maternal employment exerts no consistent detrimental effects on children. In this study, the moderating role of employment commitment and child sex on the relationship between maternal employment status and child behavior is investigated. Mothers and teachers provided behavioral ratings for 185 elementary school children (M age = 9.42 years). Employment commitment moderated the influence of employment status on mothers' and teachers' ratings of children's attention problems and immaturity: Children whose mothers' employment status and commitment were not congruent were less attentive and more immature than those whose mothers' employment status and commitment were congruent. The statistical and applied significance of these results is suggested, as is the possibility that mother-child interactions mediate the manner in which incongruencies between employment status and employment commitment influence children's inattention-immaturity.