Functional subcaste discrimination (foragers and brood-tenders) in the antCamponotus vagus scop.: polymorphism of cuticular hydrocarbon patterns

In the antCamponotus vagus, when selected foragers that had been earlier removed from the foraging arena and brood-tenders that had been earlier removed from the nest were placed together in a foraging arena, most of the brood-tenders and only a few of the selected foragers were carried back to the nest by nonselected foragers. We hypothesize that cuticular hydrocarbons serve as a cue that allows foragers to discriminate between members of their own subcaste and brood-tenders. It has been established that the proportions of certain hydrocarbons, which are the same regardless of the colony studied, vary from one worker subcaste to another and thus constitute a specific chemical signature. These hydrocarbons belong to a wide range of chemical families (alkanes, monomethylalkanes, and dimethylalkanes). The greatest differences between the two subcastes were observed on the thorax of workers. Principal component analyses performed on the hydrocarbons (or hydrocarbon combinations) corresponding to the 45 main peaks in the cuticular profiles of the head and thorax of brood-tenders and foragers of several colonies show that there exist quantitative differences between the various signatures that characterize the colony, the worker subcastes, and the various body parts within the same species, which can be classified in a hierarchy where the differences between worker subcastes are less pronounced than those between body parts or between colonies.     

Effects of landscape structure on vegetation and some animal groups after agriculture abandonment

This research was carried out on the montane belt of a south-exposed watershed in the Intermediary Alps which have been hit by agriculture abandonment. The aim of the study was to study the relationships between vegetation, landscape mosaic, and two kinds of animals using this space at different scales: roe deer (Capreolus capreolus) and earthworms (lumbricids). Landscape dynamics (post-cultural recolonisation) and landscape structure have been approached by means of the Arc/Info geographical information system (GIS). Several methods used to study on one hand roe deer distribution, and, on the other, earthworm abundance and diversity are developed. Of these, in particular, GIS processing is used to sample earthworms according to vegetation dynamics, and roe deer distribution is related to landscape heterogeneity. Earthworms are more abundant and diversified in the key steps of vegetation dynamics. These lumbricids can be considered as functional indicators of these dynamics. Results also demonstrate that both the vegetation type and the landscape heterogeneity have a direct influence on the use of the space by the roe deer. They show themselves to be structural indicators of the landscape.     

Oscillation conditions of A FIR waveguide laser

We consider the oscillation conditions of a FIR waveguide laser from a microwaves point of view. We compare our theorical results with experimental curves founded in the literature.     

Exposure of biological preparations to radiofrequency electromagnetic fields under low gravity

There is interest as to whether the electromagnetic fields used in mobile radiotelephony might affect biological processes. Other weak fields such as gravity intervene in a number of physical and biological processes. Under appropriate in vitro conditions, the macroscopic self-organization of microtubules, a major cellular component, is triggered by gravity. We wished to investigate whether self-organization might also be affected by radiotelephone electromagnetic fields. Detecting a possible effect requires removing the obscuring effects triggered by gravity. A simple manner of doing this is by rotating the sample about the horizontal. However, if the external field does not also rotate with the sample, its possible effect might also be averaged down by rotation. Here, we describe an apparatus in which both the sample and an applied radiofrequency electromagnetic field (1.8 GHz) are stationary with respect to one another while undergoing horizontal rotation. The electromagnetic field profile within the apparatus has been measured and the apparatus tested by reproducing the in vitro behavior of microtubule preparations under conditions of weightlessness. Specific adsorption rates of electromagnetic energy within a sample are measured from the initial temperature rise the incident field causes. The apparatus can be readily adapted to expose samples to various other external fields and factors under conditions of weightlessness.     

Electronic structure of the pentacene–gold interface: A density-functional theory study

The structural and electronic properties of a pentacene monolayer adsorbed on the Au(1 1 1) surface have been studied with a density-functional theory (DFT) approach. A thermally stable adsorption geometry of the pentacene monolayer on the gold surface is found, from which the adsorption energy per pentacene molecule can be evaluated. Our results illustrate how the electron charge distribution initially present over the clean gold surface is pushed back upon adsorption of the pentacene monolayer; this push-back (pillow effect) leads to a significant work-function decrease for the modified gold surface. The electronic couplings between the highest occupied molecular orbital of pentacene and the Au(1 1 1) surface and between adjacent pentacene molecules within the monolayer, were extracted from the calculated band structures; the pentacene–gold surface electronic coupling is found to be about five times smaller than the electronic coupling between pentacene molecules.     

气候变化对全球葡萄种植和葡萄酒酿造的影响

葡萄的生长与环境和气候条件有着密切的关系,因此,世界葡萄种植区局限于一定的纬度范围内.最近几年中,北半球的葡萄种植随着气候变暖已经发生了很大改变,不同的气候条件决定了不同类型的葡萄酒的生产.     

The dynamics of aroma release during consumption of candies of different structures,and relationship with temporal perception

We investigated the role of both candy texture and eating technique (melting or chewing) on the dynamics of aroma release. One novelty of this type of analysis was the simultaneous application of instrumental and sensory analysis. Four candy textures were established based on their storage modulus at 1 Hz by varying the gelatine content between 0 and 15% w/w. The invivo release of three aroma compounds was monitored using Proton Transfer Reaction Mass Spectrometry and with a trained panel of testers. The gelatine content had no significant effect on the headspace/product partition and diffusion properties of the aroma compounds. The highest invivo release for all aroma compounds was obtained with the 2% gelatine sample. Our findings indicated that aroma release was determined by interaction between the product properties and oral behaviour. Relations between the dynamics of release and perception (method of Temporal Dominance of Sensations) have been established on temporal parameters.     

Models for Audiovisual Fusion in a Noisy-Vowel Recognition Task

This paper presents a study of models for audiovisual (AV) fusion in a noisy-vowel recognition task. We progressively elaborate audiovisual models in order to respect the major principle demonstrated by human subjects in speech perception experiments (the synergy principle): audiovisual identification should always be more efficient than auditory-alone or visual-alone identification. We first recall that the efficiency of audiovisual speech recognition systems depends on the level at which they fuse sound and image: four AV architectures are presented, and two are selected for the following of the study. Secondly, we show the importance of providing a contextual input linked to the Signal-to-Noise Ratio (SNR) in the fusion process. Then we propose an original approach using an efficient nonlinear dimension reduction algorithm (curvilinear components analysis) in order to increase the performances of the two AV architectures. Furthermore, we show that this approach allows an easy and efficient estimation of the reliability of the audio sensor in relation to SNR, that this estimation can be used to control the AV fusion process, and that it significantly improves the AV performances. Hence, altogether, nonlinear dimension reduction, context estimation and control of the fusion process enable us to respect the synergy criterion for the two most used architectures.