Modèle de réponse vibratoire de planchers légers par méthodes analytiques

Pouvoir prédire le bruit transmis par un élément constructif est depuis plusieurs années une grande préoccupation. Cette problématique a été largement traitée pour les bruits aériens, mais reste plus complexe pour les bruits d'impacts. En effet les caractéristiques de l'excitation en termes d'amplitude et de contenu fréquentiel dans le cas d'un bruit d'impact dépendent autant de l'excitateur (la source de choc) que du récepteur (la paroi impactée). Or, ces bruits figurent en bonne place des sources d'insatisfaction citées par les occupants de bâtiments résidentiels, en particulier dans le cas de constructions légères. Un outil de synthèse sonore serait alors idéal pour à la fois pouvoir prédire les niveaux sonores dus à diverses sources d'impacts mais aussi évaluer le ressenti des occupants par l'écoute. Cette étude s'intéresse à simuler dans le domaine temporel la réponse vibratoire de planchers légers soumis à une excitation mécanique ponctuelle. Dans cette optique, un modèle analytique des modes de vibration d'une plaque mince orthotrope est utilisé. Pour des éléments constructifs homogènes, en béton plein par exemple, ce modèle permet de reproduire la réponse vibratoire temporelle avec un jeu limité de données d'entrées et sans nécessiter des ressources de calcul importantes. Cependant, les planchers légers sont souvent constitués de panneaux équipés de raidisseurs (solives) ou bien de lames assemblées entre elles (cas des éléments en bois lamellé croisé, dits « CLT »). Dans cette étude, ces spécificités de conception sont prises en compte en modélisant les planchers par des plaques minces orthotropes, dont les caractéristiques sont obtenues par une méthode d'homogénéisation. Après une présentation du modèle utilisé et des hypothèses sur lesquelles il s'appuie, deux applications sont présentées : la première concerne un plancher bois sur solives, et la seconde un plancher en CLT 3 couches. Les réponses vibratoires obtenues sont comparées à des résultats de mesures en laboratoire ou de simulations par éléments finis. Les résultats et perspectives sont ensuite discutés

Voice of the Psychonauts: Coping, Life Purpose, and Spirituality in Psychedelic Drug Users

Psychoactive drug use shows great diversity, but due to a disproportionate focus on problematic drug use, predominant nonproblematic drug use remains an understudied phenomenon. Historic and anecdotal evidence shows that natural sources of "psychedelic" drugs (e.g., mescaline and psilocybin) have been used in religious and spiritual settings for centuries, as well as for psychological self-enhancement purposes. Our study assessed a total of 667 psychedelic drug users, other drug users, and drug nonusers by online questionnaires. Coping, life purpose, and spirituality were measured with the Psychological Immune Competence Inventory, the Purpose in Life test, and the Intrinsic Spirituality Scale, respectively. Results indicate that the use of psychedelic drugs with a purpose to enhance self-knowledge is less associated with problems, and correlates positively with coping and spirituality. Albeit the meaning of "spirituality" may be ambiguous, it seems that a spiritually-inclined attitude in drug use may act as a protective factor against drug-related problems. The autognostic use of psychedelic drugs may be thus hypothesized as a "training situation" that promotes self-enhancement by rehearsing personal coping strategies and by gaining self-knowledge. However, to assess the actual efficiency and the speculated long-term benefits of these deliberately provoked exceptional experiences, further qualitative investigations are needed

Nitric oxide sensing in plants is mediated by proteolytic control of group VII ERF transcription factors

Nitric oxide (NO) is an important signaling compound in prokaryotes and eukaryotes. In plants, NO regulates critical developmental transitions and stress responses. Here, we identify a mechanism for NO sensing that coordinates responses throughout development based on targeted degradation of plant-specific transcriptional regulators, the group VII ethylene response factors (ERFs). We show that the N-end rule pathway of targeted proteolysis targets these proteins for destruction in the presence of NO, and we establish them as critical regulators of diverse NO-regulated processes, including seed germination, stomatal closure, and hypocotyl elongation. Furthermore, we define the molecular mechanism for NO control of germination and crosstalk with abscisic acid (ABA) signaling through ERF-regulated expression of ABSCISIC ACID INSENSITIVE5 (ABI5). Our work demonstrates how NO sensing is integrated across multiple physiological processes by direct modulation of transcription factor stability and identifies group VII ERFs as central hubs for the perception of gaseous signals in plants

Individual rules for trail pattern formation in Argentine ants (Linepithema humile)

We studied the formation of trail patterns by Argentine ants exploring an empty arena. Using a novel imaging and analysis technique we estimated pheromone concentrations at all spatial positions in the experimental arena and at different times. Then we derived the response function of individual ants to pheromone concentrations by looking at correlations between concentrations and changes in speed or direction of the ants. Ants were found to turn in response to local pheromone concentrations, while their speed was largely unaffected by these concentrations. Ants did not integrate pheromone concentrations over time, with the concentration of pheromone in a 1 cm radius in front of the ant determining the turning angle. The response to pheromone was found to follow a Weber's Law, such that the difference between quantities of pheromone on the two sides of the ant divided by their sum determines the magnitude of the turning angle. This proportional response is in apparent contradiction with the well-established non-linear choice function used in the literature to model the results of binary bridge experiments in ant colonies (Deneubourg et al. 1990). However, agent based simulations implementing the Weber's Law response function led to the formation of trails and reproduced results reported in the literature. We show analytically that a sigmoidal response, analogous to that in the classical Deneubourg model for collective decision making, can be derived from the individual Weber-type response to pheromone concentrations that we have established in our experiments when directional noise around the preferred direction of movement of the ants is assumed.Comment: final version, 9 figures, submitted to Plos Computational Biology (accepted

Differential effects of mTOR inhibition and dietary ketosis in a mouse model of subacute necrotizing encephalomyelopathy

Genetic mitochondrial diseases are the most frequent cause of inherited metabolic disorders and one of the most prevalent causes of heritable neurological disease. Leigh syndrome is the most common clinical presentation of pediatric mitochondrial disease, typically appearing in the first few years of life, and involving severe multisystem pathologies. Clinical care for Leigh syndrome patients is difficult, complicated by the wide range of symptoms including characteristic progressive CNS lesion, metabolic sequelae, and epileptic seizures, which can be intractable to standard management. While no proven therapies yet exist for the underlying mitochondrial disease, a ketogenic diet has led to some reports of success in managing mitochondrial epilepsies, with ketosis reducing seizure risk and severity. The impact of ketosis on other aspects of disease progression in Leigh syndrome has not been studied, however, and a rigorous study of the impact of ketosis on seizures in mitochondrial disease is lacking. Conversely, preclinical efforts have identified the intracellular nutrient signaling regulator mTOR as a promising therapeutic target, with data suggesting the benefits are mediated by metabolic changes. mTOR inhibition alleviates epilepsies arising from defects in TSC, an mTOR regulator, but the therapeutic potential of mTOR inhibition in seizures related to primary mitochondrial dysfunction is unknown. Given that ketogenic diet is used clinically in the setting of mitochondrial disease, and mTOR inhibition is in clinical trials for intractable pediatric epilepsies of diverse causal origins, a direct experimental assessment of their effects is imperative. Here, we define the impact of dietary ketosis on survival and CNS disease in the Ndufs4(KO) mouse model of Leigh syndrome and the therapeutic potential of both dietary ketosis and mTOR inhibition on seizures in this model. These data provide timely insight into two important clinical interventions

Finding and sharing: new approaches to registries of databases and services for the biomedical sciences

The recent explosion of biological data and the concomitant proliferation of distributed databases make it challenging for biologists and bioinformaticians to discover the best data resources for their needs, and the most efficient way to access and use them. Despite a rapid acceleration in uptake of syntactic and semantic standards for interoperability, it is still difficult for users to find which databases support the standards and interfaces that they need. To solve these problems, several groups are developing registries of databases that capture key metadata describing the biological scope, utility, accessibility, ease-of-use and existence of web services allowing interoperability between resources. Here, we describe some of these initiatives including a novel formalism, the Database Description Framework, for describing database operations and functionality and encouraging good database practise. We expect such approaches will result in improved discovery, uptake and utilization of data resources. Database URL: http://www.casimir.org.uk/casimir_dd

First Observation of CP Violation in B0->D(*)CP h0 Decays by a Combined Time-Dependent Analysis of BaBar and Belle Data

We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.Comment: 9 pages, 2 figures, submitted to Physical Review Letter