Path integral regularization of pure Yang-Mills theory

In enlarging the field content of pure Yang-Mills theory to a cutoff dependent matrix valued complex scalar field, we construct a vectorial operator, which is by definition invariant with respect to the gauge transformation of the Yang-Mills field and with respect to a Stueckelberg type gauge transformation of the scalar field. This invariant operator converges to the original Yang-Mills field as the cutoff goes to infinity. With the help of cutoff functions, we construct with this invariant a regularized action for the pure Yang-Mills theory. In order to be able to define both the gauge and scalar fields kinetic terms, other invariant terms are added to the action. Since the scalar fields flat measure is invariant under the Stueckelberg type gauge transformation, we obtain a regularized gauge-invariant path integral for pure Yang-Mills theory that is mathematically well defined. Moreover, the regularized Ward-Takahashi identities describing the dynamics of the gauge fields are exactly the same as the formal Ward-Takahashi identities of the unregularized theory.Comment: LaTeX file, 24 pages, improved version, to be published in Phys. Rev.

Mise en ligne d'un microscope digitalisé et télécommandé

On décrit la mise en ligne avec un calculateur d'un microscope digitalisé en x, y, z, et télécommandé, pour les mesures dans l'émulsion ionographique

Functionnal biodiversity in mango orchards on Reunion. Ecosystemic and landscape effects on epigeous predatory arthropods.

The knowledge of factors implicated in agroecosystem diversity is necessary to better evaluate their role. The study aims to link within-field plant diversity, cultural practices, and landscape context with terrestrial predatory arthropods in mango orchards on Reunion. Twenty-four plots distributed within the mango production area have been studied. Arthropods were sampled with pitfall traps. The land plots were grouped into three groups of agricultural practice intensity. The landscape was mapped within a circle of 400 meters around the orchards, which permitted to distinguish three different landscape contexts. Based on 83181 arthropods collected, 65124 were determined as predators, their communities were mainly composed of ants (Hymenoptera: Formicinae) and spiders (Araneae). The species richness and their equitability were influenced by factors at three different scales: (1) the within-field plant diversity improved evenness of predatory arthropods communities; (2) the moderate farming practices, as organic farming practices, had higher species richness than those obtained with “conventionnal” practices; (3) a landscape context with relevant heterogeneity and fragmentation increased the species richness of epigeal predatory arthropods in mango orchards

Influence of thermophysiology on thermal behavior: the essentials of categorization

Predicted energy use of dwellings often deviates from the actual energy use. Thermoregulatory behavior of the occupant might explain this difference. Such behavior is influenced by thermal sensation and thermal comfort. These subjective ratings in turn are linked to physiological parameters such as core and skin temperatures. However, it is unclear which physiological parameters best predict thermoregulatory behavior. The objective of this research was to study physiological parameters that potentially can be used to predict thermoregulatory behavior. Sixteen healthy females (18-30years) were exposed to two dynamic temperature protocols: a gradual increase (+4K/h, ranging from 24 degrees C to 32 degrees C) and a gradual decrease in ambient temperature (-4K/h, ranging from 24 degrees C to 16 degrees C). During the experiments physiological responses, thermal sensation, thermal preference and the intention of thermoregulatory behavior were measured. Thermal sensation is highly correlated with thermal preference (r=-0.933, P<0.001). The skin temperature of the wrist best predicts thermal sensation (R2=0.558, P<0.001) and therefore seems useful as a physiological parameter to predict the intention of thermoregulatory behavior. When the subjects are categorized based on their thermal sensation votes, more precise predictions of thermal sensation can be made. This categorization therefore can be of value for the determination of the actual energy use of occupant in dwellings

Low density instability in a nuclear Fermi liquid drop

The instability of a Fermi-liquid drop with respect to bulk density distortions is considered. It is shown that the presence of the surface strongly reduces the growth rate of the bulk instability of the finite Fermi-liquid drop because of the anomalous dispersion term in the dispersion relation. The instability growth rate is reduced due to the Fermi surface distortions and the relaxation processes. The dependence of the bulk instability on the multipolarity of the particle density fluctuations is demonstrated for two nuclei $^{40}Ca$ and $^{208}Pb$.Comment: 12 pages, latex, 3 ps-figures, submitted to Phys. Rev.

Characterization of superconducting multilayers samples

Best RF bulk niobium accelerating cavities have nearly reached their ultimate limits at rf equatorial magnetic field H 200 mT close to the thermodynamic critical field Hc. In 2006 Gurevich proposed to use nanoscale layers of superconducting materials with high values of Hc &gt; HcNb for magnetic shielding of bulk niobium to increase the breakdown magnetic field inside SC RF cavities [1]. Depositing good quality layers inside a whole cavity is rather difficult but we have sputtered high quality samples by applying the technique used for the preparation of superconducting electronics circuits and characterized these samples by X-ray reflectivity, dc resistivity (PPMS) and dc magnetization (SQUID). Dc magnetization curves of a 250 nm thick Nb film have been measured, with and without a magnetron sputtered coating of a single or multiple stack of 15 nm MgO and 25 nm NbN layers. The Nb samples with/without the coating clearly exhibit different behaviors. Because SQUID measurements are influenced by edge and shape effects we propose to develop a specific local magnetic measurement of HC1 based on ac third harmonic analysis in order to reveal the screening effect of multilayers

Status report on GANIL-SPIRAL1

International audienceThe GANIL facility (Caen, France) (Figure 1) is dedicated to the acceleration of heavy ion beams for nuclear physics, atomic physics, radiobiology and material irradiation. The production of radioactive ion beams for nuclear physics studies represents the main part of the activity. Two complementary methods are used: the Isotope Separation On-Line (ISOL, the SPIRAL1 facility) and the In-Flight Separation techniques (IFS). SPIRAL1, the ISOL facilty, is running since 2001, producing and post-accelerating radioactive ion beams. The energy range available goes from 1.2 MeV/A to 25 MeV/A with a compact cyclotron (CIME, K=265). The running mode of this machine will be recalled as well as a review of the operation from 2001 to 2006. A point will be done on the past, present and future projects which allow to continue to develop the capacities of this equipment and to answer the new demands from the physicists, such as new beamlines for low or high energy experiments, new diagnotics of control or the adaptation of an identification system using Silicon, Germanium or plastic detectors in the requirements of the operation evironnement

Autonomy and forage grasses in goat farming of western France First results of a sociological survey

International audienceOur communication is based on the results of a multidisciplinary research (PSDR FLECHE-Fromages et Laits issus d'Élevages de Chèvres conduites avec de l'Herbe-2016-2020) which aims to study the potential of grass valorization in goat systems, with the dual objective of strengthening the economic resilience of farms and the social image of the dairy goat sector of Western France. The latter currently represent almost half of the national goat population and 58% of the milk supplied in France. The sociological aspect of the research concerns the representations, value systems, interests and constraint systems (technical, economic, etc.) that guide the practices of all the actors in the sector: farmers, upstream and downstream actors. The objective of this approach is to analyse, at all levels of the value chain, the incentives and obstacles to a possible transition to more grassy feeding systems. Based on 76 semi-directive interviews, this paper presents the first results of this survey by showing how contextual elements (socio-economic, professional, etc.) impact farmers' choices of practices. While, in principle, the whole goat sector seems to be converging towards an agro-ecological transition that ensures its sustainability, in practice, each of its actors is confronted with a system of constraints that limit actual developments. The articulation of these obstacles seems to lead to a kind of inertia, which prevents the adoption of practices that are nevertheless perceived as recommendable by most actors. Autonomie et fourrages herbagers dans les élevages caprins de l'Ouest de la France. Premiers résultats d'une enquête sociologique. Résumé. Notre communication s'inscrit dans le cadre d'une recherche pluridisciplinaire (Programme PSDR-FLECHE-Fromages et Laits issus d'Élevages de Chèvres conduites avec de l'Herbe-2016-2020) qui vise à étudier le potentiel de valorisation de l'herbe dans les systèmes caprins, dans le double objectif de renforcer la résilience économique des exploitations et l'image sociale des filières caprines laitières de l'Ouest de la France. Ces dernières représentent actuellement près de la moitié de l'effectif national de chèvres et 58% du lait livré en France. Le volet sociologique de la recherche porte sur les représentations, les systèmes de valeurs, les intérêts et les systèmes de contraintes (techniques, économiques, etc.) qui orientent les pratiques de l'ensemble des acteurs de la filière : éleveurs, acteurs de l'amont et de l'aval. L'objectif de cette démarche est d'analyser, à tous les niveaux de la filière, les incitations et les freins à une éventuelle transition vers des systèmes alimentaires plus herbagers. A partir de 76 entretiens semi-directifs, ce papier présente les premiers résultats de cette enquête en montrant, notamment, comment les éléments contextuels (socio-économiques, professionnels, etc.) impactent les choix des pratiques des exploitants agricoles. Si, en principe, l'ensemble de la filière caprine semble converger vers une transition agroécologique qui en assure la durabilité, dans la pratique, chacun de ses acteurs est confronté à un univers de contraintes qui limitent les évolutions effectives. L'articulation des freins relevant des différents maillons de la filière, semble ainsi déboucher sur une sorte d'inertie, qui empêche l'adoption de pratiques pourtant perçues comme souhaitables par la plupart des acteurs. Mots-clés. Autonomie-fourrages herbagers-caprins-sociologie