A new experiment to search for the invisible decay of the orthopositronium

We propose an experiment to search for invisible decays of orthopositronium (o-Ps) with a 90% confidence sensitivity in the branching ratio as low as $10^{-8}$. Evidence for this decay mode would unambigously signal new physics: either the existence of extra--dimensions or fractionally charged particles or new light gauge bosons. The experimental approach and the detector components of the proposed experiment are described.Comment: Based on a talk given at Workshop on Positronium Physics, Zurich, Switzerland, 30-31 May 200

Les peuplements de poissons de la Camargue

Fish communities in the Camargue wetlands, both temporary and permanent marshes as weil as irrigation and drainage canals, were studied from 1977 to 1980. The main part of this work was carried out in wetlands isolated from direct contact with the sea by a dike, the Digue à la mer. Three major types of wetlands and their associated fish species are described in the Camargue : the freshwater (0-5 g/1 Cl-), the brackish (5-16 g/1 Cl-), and the very brackish (16-35 g/1 Cl-). A significant relationship (P < 0.01 ) was found between the species richness and the surface area. The slope of this regression (0.134) is lower than that found for other aquatic systems. Four associations of fish were determined and their meaning is discussed . The biomass of temporary freshwater marshes ranged between 13 to 76 kg/ha and was much lower than those found in the small freshwater canals : 112 to 2 544 kg/ha. Common carp, Cyprinus carpio L., is the dominant species in freshwater wetlands (70 to 85 % of total biomass). A space partitioning between the immature and the adult carp is described. ln one waterbody studied south of the Digue à la mer, linked temporarily with the sea, the fish community composition underwent frequent and rapid changes according to the variations of environmental factors. The salinity appeared to be the most important factor affecting diversity and eveness of the fish community in this etang. A canonical analysis was used to determine which of the environmental factors bad the greatest impact on the abundance of the different fish genus. Only 46.2 % of the fish species studied reproduce in the Camargue, while 35.9 % migrate to the sea for spawning. The importance of a link with the sea as weil as that of a sound water management plan for the Camargue as a whole are pointed ou

Why do Great White Pelican chicks die suddenly on Arel island, Banc d'Arguin, in Mauritania ?

Le statut du Pélican blanc en Afrique dans les années quatre-vingts est passé en revue. Pendant cette période la taille de la colonie de Pelecanus onocrotalus située sur la côte mauritanienne au Banc d'Arguin a été multipliée par dix grâce à un afflux d'individus provenant des nouvelles colonies sénégalaises. Les Pélicans blancs sont absents de février à juin sur le banc d'Arguin. Les premiers s'installent sur le banc en juillet au moment où arrivent à ce niveau les eaux chaudes provenant du golfe de Guinée. Les pélicans pondent leurs oeufs par vagues, de la mi-août à la fin novembr

A mathematical model for cell cycle-specific cancer virotherapy

Oncolytic viruses preferentially infect and replicate in cancerous cells, leading to elimination of tumour populations, while sparing most healthy cells. Here, we study the cell cycle-specific activity of viruses such as vesicular stomatitis virus (VSV). In spite of its capacity as a robust cytolytic agent,VSVcannot effectively attack certain tumour cell types during the quiescent, or resting, phase of the cell cycle. In an effort to understand the interplay between the time course of the cell cycle and the specificity of VSV, we develop a mathematical model for cycle-specific virus therapeutics. We incorporate the minimum biologically required time spent in the non-quiescent cell cycle phases using systems of differential equations with incorporated time delays. Through analysis and simulation of the model, we describe how varying the minimum cycling time and the parameters that govern viral dynamics affect the stability of the cancer-free equilibrium, which represents therapeutic success

Facial displays are tools for social influence

Open access articleBased on modern theories of signal evolution and animal communication, the behavioral ecology view of facial displays (BECV) reconceives our ‘facial expressions of emotion’ as social tools that serve as lead signs to contingent action in social negotiation. BECV offers an externalist, functionalist view of facial displays that is not bound to Western conceptions about either expressions or emotions. It easily accommodates recent findings of diversity in facial displays, their public context-dependency, and the curious but common occurrence of solitary facial behavior. Finally, BECV restores continuity of human facial behavior research with modern functional accounts of non-human communication, and provides a non-mentalistic account of facial displays well-suited to new developments in artificial intelligence and social robotics

The diet of the mosquitofish Gambusia affinis (Baird and Girard) (Poecilliidae) in Mediterranean France

Le régime alimentaire de Gambusia affinis, espèce introduite en Camargue, est essentiellement constitué par des crustacés d'octobre à mai. Pendant la période de reproduction, de juin à septembre, les poissons mangent surtout des insectes aquatiques. Le régime alimentaire des mâles matures et celui des immatures se chevauche considérablement (61.9-95.6 %). Les femelles matures, présentes seulement de juin à septembre, mangent plus d'insectes terrestes à la surface de l'eau et d'insectes aquatiques que les autres classes de poissons. Par conséquent, leur régime alimentaire se distingue bien de celui des autres poissons. La même chose est observée si l'on considère la taille des proies ingérées. La grande taille des femelles matures leur permet d'exploiter une source de nourriture qui n'est pas disponible pour les autres classes de poissons. Lorsque la prédation par les poissons réduit l'abondance des proies les plus petites, il se crée une situation potentielle de compétition intraspécifique pour la nourriture. Les femelles matures, cependant, peuvent pleinement satisfaire leurs besoins alimentaires, intenses en période de reproduction, en exploitant des ressources différentes des autres classes de poissons, et elles peuvent ainsi maximiser leur succès de reproductio

Inside-Out: From Basic Emotions Theory to the Behavioral Ecology View

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI or URI link.Basic Emotions Theory (BET) is the most popular and deeply rooted psychological theory of both emotion and the facial behavior held to express it. We review its Western foundations and the key developments in its evolution, focusing on its parsing of facial expressions into two kinds: biological, categorical, iconic, universal “facial expressions of emotion,” versus modified, culturally diverse versions of those iconic expressions due to intermediation by learned “display rules.” We suggest that this dichotomy and its many corollaries are oversimplified, and that many of BET’s recent modifications are inconsistent in ways that may render it impossible to test and immune to falsification. In contrast, we suggest that the behavioral ecology view of facial displays, as an externalist and functionalist approach, resolves the quandaries and contradictions embedded in BET’s precepts and extensions