Variable Probabilities of Suit and Liability Rules

This note provides an additional argument in favour of the use of a negligence rule in tort law. When the probability of suit varies among injurers and is not observable by the judge, the judge will fail to implement the socially optimal level of care using a strict liability rule (for this implies to set damages equal to harm multiplied by the inverse of the probability of suit). However, he can still implement it using a negligence rule, subject to the condition that he chooses the negligence standard properly (for if damages are set large enough, potential injurers will comply with the standard, regardless their probability of suit).Liability, asymmetric information

Optimal decentralized management of a natural resource

We construct an economic mechanism to realize in Nash equilibrium an optimal consumption time path of a natural resource. For exposition convenience, the analysis is conducted within the model initiated by Levhari and Mirman (1980). This framework allows us to explicitly calculate the consumption time paths of the resource, associated with an open-access regime, with a cooperative management and with a (stationary Markovian) Nash equilibrium of the di¤erence game induced by the proposed mechanism.Natural resource; Fish war; Difference game; Mechanism design

On the Existence of Anonymous and Balanced Mechanisms Implementing the Lindahl Allocations

In this note, we discuss the existence of anonymous and balanced mechanisms to implement the Lindahl allocations. We obtain an impossibility result for the class of mechanisms defining an homeomorphism between the message space and the allocation space.Lindahl equilibrium ; economic mechanism

LOW BACK PAIN: BIOMECHANICS ANALYSIS AND PREVENTION

Epidemiological studies have shown that lower back pain from golf represent 25% of all golf related injuries. A review of the literature shows that the etiology is pluri-factorial, with general and specific risk factors. For the average players and the elite players, the mechanical loadings on the lumbar spine must be analyzed during all the golf swing. The specific risk factors, as range of motion restriction, abnormal muscle recruitment, excessive X-factor, important right side bending with high velocity lumbar rotation (crunch factor) are essential elements to be considered in a prevention strategy. Golf can aggravate pre-existing low back pain, especially in a context of overuse, without correct warm-up and with important golf swing technical fault but golf could also be an efficient treatment when it is practiced in good conditions

The orthology of HLA-E and H2-Qa1 is hidden by their concerted evolution with other MHC class I molecules

BACKGROUND: Whether MHC molecules undergo concerted evolution or not has been the subject of a long-standing debate. RESULTS: By comparing sequences of eight functional homologues of HLA-E from primates and rodents with those of MHC class Ia molecules from the same eight species, we find that different portions of MHC class I molecules undergo different patterns of evolution. By focusing our analyses sequentially on these various portions, we have obtained clear evidence for concerted evolution of MHC class I molecules, suggesting the occurrence of extensive interallelic and intergenic exchanges. Intra-species homogenisation of sequences is particularly noticeable at the level of exon 4, which codes for the α3 domain, but our results suggest that homogenisation also concerns certain residues of the α1–α2 codomain that lie outside the antigen recognition site. CONCLUSION: A model is presented in which Darwinian selective pressures due to pathogens could, at the same time, favour diversification of MHC class Ia molecules and promote concerted evolution of separate loci by spreading advantageous motifs arising by mutations in individual MHC molecules to other alleles and to other loci of the MHC region. This would also allow MHC molecules to co-evolve with the proteins with which they interact to fulfil their functions of antigen presentation and regulation of NK cell activity. One of the raisons d'être of the MHC may therefore be to favour at the same time both diversification of MHC class Ia molecules and homogenisation of the whole pool of MHC class I molecules (Ia and Ib) involved in antigen presentation. REVIEWERS: This article was reviewed by Stephan Beck, Lutz Walter and Pierre Pontarotti

Latent classes of nonresponders, rapid responders, and gradual responders in depressed outpatients receiving antidepressant medication and psychotherapy

BackgroundWe used growth mixture modeling (GMM) to identify subsets of patients with qualitatively distinct symptom trajectories resulting from treatment. Existing studies have focused on 12-week antidepressant trials. We used data from a concurrent antidepressant and psychotherapy trial over a 6-month period. MethodEight hundred twenty-one patients were randomized to receive either fluoxetine or tianepine and received cognitive-behavioral therapy, supportive therapy, or psychodynamic therapy. Patients completed the Montgomery-angstrom sberg depression rating scale (MADRS) at the 0, 1, 3, and 6-month periods. Patients also completed measures of dysfunctional attitudes, functioning, and personality. GMM was conducted using MADRS scores and the number of growth classes to be retained was based on the Bayesian information criterion. ResultsCriteria supported the presence of four distinct latent growth classes representing gradual responders of high severity (42% of sample), gradual responders of moderate severity (31%), nonresponders (15%), and rapid responders (11%). Initial severity, greater use of emotional coping strategies, less use of avoidance coping strategies, introversion, and less emotional stability predicted nonresponder status. Growth classes were not associated with different treatments or with proportion of dropouts. ConclusionsThe longer time period used in this study highlights potential overestimates of nonresponders in previous research and the need for continued assessments. Our findings demonstrate distinct growth trajectories that are independent of treatment modality and generalizable to most psychotherapy patients. The correlates of class membership provide directions for future studies, which can refine methods to predict likely nonresponders as a means to facilitate personalized treatments

Insights into the regulation of small RNA expression: SarA represses the expression of two sRNAs in Staphylococcus aureus

International audienceThe opportunistic pathogen Staphylococcus aureus expresses transcription factors (TFs) and regulatory small RNAs (sRNAs) which are essential for bacterial adaptation and infectivity. Until recently, the study of S. aureus sRNA gene expression regulation was under investigated, but it is now an expanding field. Here we address the regulation of Srn 3610 SprC sRNA, an attenuator of S. aureus virulence. We demonstrate that SarA TF represses srn 3610 sprC transcription. DNase I footprinting and deletion analyses show that the SarA binding site on srn 3610 sprC belongs to an essential 22 bpDNA region. Comparative analysis also revealed another possible site, this time in the srn 9340 promoter. SarA specifically binds these two sRNA promoters with high affinity in vitro and also repressestheir transcription in vivo. Chromatin immunoprecipitation (ChIP) assays confirmed SarA attachment to both promoters. ChIP and electrophoretic mobility shift assays targeting sigmaA RNA polymerase subunitor using bacterial RNA polymerase holoenzyme suggestedthat SarA and the sigmaA bind srn 3610 sprC and srn 9340 promoters in a mutually exclusive way. Beyond the mechanistic study of SarA repression of these two sRNAs, this work also suggests that some S. aureus sRNAs belong to the same regulon and act jointly in responding to environmental changes