1-D Coordinate Based on Local Information for MAC and Routing Issues in WSNs

More and more critical Wireless Sensor Networks (WSNs) applications are emerging. Those applications need reliability and respect of time constraints. The underlying mechanisms such as MAC and routing must handle such requirements. Our approach to the time constraint problem is to bound the hop-count between a node and the sink and the time it takes to do a hop so the end-to-end delay can be bounded and the communications are thus real-time. For reliability purpose we propose to select forwarder nodes depending on how they are connected in the direction of the sink. In order to be able to do so we need a coordinate (or a metric) that gives information on hop-count, that allows to strongly differentiate nodes and gives information on the connectivity of each node keeping in mind the intrinsic constraints of WSWs such as energy consumption, autonomy, etc. Due to the efficiency and scalability of greedy routing in WSNs and the financial cost of GPS chips, Virtual Coordinate Systems (VCSs) for WSNs have been proposed. A category of VCSs is based on the hop-count from the sink, this scheme leads to many nodes having the same coordinate. The main advantage of this system is that the hops number of a packet from a source to the sink is known. Nevertheless, it does not allow to differentiate the nodes with the same hop-count. In this report we propose a novel hop-count-based VCS which aims at classifying the nodes having the same hop-count depending on their connectivity and at differentiating nodes in a 2-hop neighborhood. Those properties make the coordinates, which also can be viewed as a local identifier, a very powerful metric which can be used in WSNs mechanisms.Comment: (2011

RTXP : A Localized Real-Time Mac-Routing Protocol for Wireless Sensor Networks

Protocols developed during the last years for Wireless Sensor Networks (WSNs) are mainly focused on energy efficiency and autonomous mechanisms (e.g. self-organization, self-configuration, etc). Nevertheless, with new WSN applications, appear new QoS requirements such as time constraints. Real-time applications require the packets to be delivered before a known time bound which depends on the application requirements. We particularly focus on applications which consist in alarms sent to the sink node. We propose Real-Time X-layer Protocol (RTXP), a real-time communication protocol. To the best of our knowledge, RTXP is the first MAC and routing real-time communication protocol that is not centralized, but instead relies only on local information. The solution is cross-layer (X-layer) because it allows to control the delays due to MAC and Routing layers interactions. RTXP uses a suited hop-count-based Virtual Coordinate System which allows deterministic medium access and forwarder selection. In this paper we describe the protocol mechanisms. We give theoretical bound on the end-to-end delay and the capacity of the protocol. Intensive simulation results confirm the theoretical predictions and allow to compare with a real-time centralized solution. RTXP is also simulated under harsh radio channel, in this case the radio link introduces probabilistic behavior. Nevertheless, we show that RTXP it performs better than a non-deterministic solution. It thus advocates for the usefulness of designing real-time (deterministic) protocols even for highly unreliable networks such as WSNs

Learning the optimal buffer-stock consumption rule of Carroll

This article questions the rather pessimistic conclusions of Allen et Carroll (2001) about the ability of consumer to learn the optimal buffer-stock based consumption rule. To this aim, we develop an agent based model where alternative learning schemes can be compared in terms of the consumption behaviour that they yield. We show that neither purely adaptive learning, nor social learning based on imitation can ensure satisfactory consumption behaviours. By contrast, if the agents can form adaptive expectations, based on an evolving individual mental model, their behaviour becomes much more interesting in terms of its regularity, and its ability to improve performance (which is as a clear manifestation of learning). Our results indicate that assumptions on bounded rationality, and on adaptive expectations are perfectly compatible with sound and realistic economic behaviour, which, in some cases, can even converge to the optimal solution. This framework may therefore be used to develop macroeconomic models with adaptive dynamics.Consumption decisions; Learning; Expectations; Adaptive behaviour; Computational economics

Breaking Bad News: the TAKE five program

Introduction For years, bad news delivery’s impact on patients or their relatives, as well as physicians’ stress has been a major concern. Based on studies claiming the efficacy of training courses to help physicians delivering such news, many protocols, like SPIKES, BREAKS or SHARE, have emerged worldwide. However, training to such protocol might be time-consuming and not suitable with junior doctors or trainees’ turnover. We hypothesised that a standardized 5-hours training program could improve bad news delivery practice. Participants and methods This preliminary study was conducted in the ED of a tertiary care academic hospital accounting for 90000 ED census per year, 16 attending physicians, 10 junior residents, and 5 trainees per month. Data were collected between November 2015 and April 2016. The study included 3 phases over 4 weeks. Video recorded single role-playing sessions happened the 1st (T1) and the 4th (T3) weeks. A 3-hour theory lesson happened the second week (T2), introducing the basics of therapeutic communication and delivering bad news. Each role-playing session lasted almost 1 hour (10 minutes briefing and medical case reading, 10 minutes role-plays and 40 minutes group debriefing). Bad news delivery performance was evaluated by a 14-points retrospective assessment tool (1). We collected data about the status and impact of a stressful event at 3-days using the French version of the IES-R scale (2). We applied Student t-tests for statistical analysis. Results 14 volunteers (10 trainees and 4 junior emergency physicians) were included in the study. On average, bad-news delivery process took 9’45’’ at T1 and 10’20’’ at T3. From T1 to T3, bad-news delivery performance increased significantly for both junior emergency physicians and trainees (p=0.0003 and p=0.0006, respectively). Further analysis revealed that most relevant increases involved the “situation” (p<0.001), “presentation” (p=0.009), “knowledge” (p=0.037), “emotions” (p=0.01) and “summary” (p=0.001) steps. We also found a significant decrease of the impact of bad-news delivery on trainee physicians’ stress (p=0.006). Discussion and conclusion These preliminary results indicate some potential for this new standardized course of bad news delivery. Apart from allowing physicians increase their communications skills, we believe that this simple 5-hour simulation-training program could alleviate physicians’ stress when they happen to break bad news. References 1. Brunet, A. et al. (2003). Validation of a French version of the Impact of Event Scale-Revised. Can J Psychiatry, 48(1), 56-61. 2. Park, I. et al. (2010). Breaking bad news education for emergency medicine residents: A novel training module using simulation with the SPIKES protocol. J Emerg Trauma Shock, 3(4), 385-388

Darker eumelanic barn owls better withstand food depletion through resistance to food deprivation and lower appetite

The intensity of selection exerted on ornaments typically varies between environments. Reaction norms may help to identify the conditions under which ornamented individuals have a selective advantage over drab conspecifics. It has been recently hypothesized that in vertebrates eumelanin-based coloration reflects the ability to regulate the balance between energy intake and expenditure. We tested two predictions of this hypothesis in barn owl nestlings, namely that darker eumelanic individuals have a lower appetite and lose less weight when food-deprived. We found that individuals fed ad libitum during 24h consumed less food when their plumage was marked with larger black spots. When food-deprived for 24h nestlings displaying larger black spots lost less weight. Thus, in the barn owl the degree of eumelanin-based coloration reflects the ability to withstand periods of food depletion through lower appetite and resistance to food restriction. Eumelanic coloration may therefore be associated with adaptations to environments where the risk of food depletion is hig

III-V photonic crystal wire cavity laser on silicon wafer

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A Major Locus Controls a Genital Shape Difference Involved in Reproductive Isolation Between Drosophila yakuba and Drosophila santomea

International audienceRapid evolution of genitalia shape, a widespread phenomenon in animals with internal fertilization, offers the opportunity to dissect the genetic architecture of morphological evolution linked to sexual selection and speciation. Most quantitative trait loci (QTL) mapping studies of genitalia divergence have focused on Drosophila melanogaster and its three most closely related species, D. simulans, D. mauritiana, and D. sechellia, and have suggested that the genetic basis of genitalia evolution involves many loci. We report the first genetic study of male genitalia evolution between D. yakuba and D. santomea, two species of the D. melanogaster species subgroup. We focus on male ventral branches, which harm females during interspecific copulation. Using landmark-based geometric morphometrics, we characterized shape variation in parental species, F1 hybrids, and backcross progeny and show that the main axis of shape variation within the backcross population matches the interspecific variation between parental species. For genotyping, we developed a new molecular method to perform multiplexed shotgun genotyping (MSG), which allowed us to prepare genomic DNA libraries from 365 backcross individuals in a few days using little DNA. We detected only three QTL, one of which spans 2.7 Mb and exhibits a highly significant effect on shape variation that can be linked to the harmfulness of the ventral branches. We conclude that the genetic architecture of genitalia morphology divergence may not always be as complex as suggested by previous studies