Limiting the propagation of localization errors in multi-hop wireless networks

This paper concerns a study of the process of localizing the nodes of a multi-hop wireless networks, i.e., of having the node computing their coordinates with respect to a suitable reference system. We consider networks where the nodes perform measurements of distance and angle of arrival from nodes within their transmission radius. We describe a simple localization protocol, termed Range-Based Centroid (RBC), that starting from a single node (the beacon) with given coordinates localizes all the network nodes with reasonable accuracy. We then propose a new localization protocol that achieves greater accuracy by containing the propagation of the localization error as the process progresses away from the beacon. We quantify the improvements of the proposed protocol, termed MEC 2 (for Minimum Enclosing Circle Containment) by simulations. In the considered scenarios, MEC 2 keeps the localization error within 21% of the nodes' transmission radius, with 20-30% improvements over RBC. © 2006 IEEE

Prenatal and postnatal influences on behavioral development in a mouse model of preconceptional stress

Depression during pregnancy is detrimental for the wellbeing of the expectant mother and can exert long-term consequences on the offspring's development and mental health. In this context, both the gestational environment and the postpartum milieu may be negatively affected by the depressive pathology. It is, however, challenging to assess whether the contributions of prenatal and postnatal depression exposure are distinct, interactive, or cumulative, as it is unclear whether antenatal effects are due to direct effects on fetal development or because antenatal symptoms continue postnatally. Preclinical models have sought to answer this question by implementing stressors that induce a depressive-like state in the dams during pregnancy and studying the effects on the offspring. The aim of our present study was to disentangle the contribution of direct stress in utero from possible changes in maternal behavior in a novel model of preconceptional stress based on social isolation rearing (SIR). Using a cross-fostering paradigm in this model, we show that while SIR leads to subtle changes in maternal behavior, the behavioral changes observed in the offspring are driven by a complex interaction between sex, and prenatal and postnatal maternal factors. Indeed, male offspring are more sensitive to the prenatal environment, as demonstrated by behavioral and transcriptional changes driven by their birth mother, while females are likely affected by more complex interactions between the pre and the postpartum milieu, as suggested by the important impact of their surrogate foster mother. Taken together, our findings suggest that male and female offspring have different time-windows and behavioral domains of susceptibility to maternal preconceptional stress, and thus underscore the importance of including both sexes when investigating the mechanisms that mediate the negative consequences of exposure to such stressor