Maggay\u27s Global kingdom, global people: Living faithfully in a multicultural world

Ce numéro de Trivium est consacré à un aspect de la réflexion de l’un des plus grands représentants de la pensée sociale en France, Emile Durkheim (1858-1917). Aussi bien en dehors qu’au dedans des cercles de spécialistes, on attribue communément à Durkheim la fondation de la sociologie comme discipline scientifique autonome ; on l’évoque comme l’un des « pères fondateurs », et aussi comme l’un des plus éminents représentants, de cette branche des sciences sociales. Qu’il existe un rapport ét..

Anomalous Behavior of Spin Systems with Dipolar Interactions

We study the properties of spin systems realized by cold polar molecules interacting via dipole-dipole interactions in two dimensions. Using a spin wave theory, that allows for the full treatment of the characteristic long-distance tail of the dipolar interaction, we find several anomalous features in the ground state correlations and the spin wave excitation spectrum, which are absent in their counterparts with short range interaction. The most striking consequence is the existence of true long-range order at finite temperature for a two-dimensional phase with a broken U(1) symmetry.Comment: 6 pages, 3 figure

Properties of principal component methods for functional and longitudinal data analysis

The use of principal component methods to analyze functional data is appropriate in a wide range of different settings. In studies of ``functional data analysis,'' it has often been assumed that a sample of random functions is observed precisely, in the continuum and without noise. While this has been the traditional setting for functional data analysis, in the context of longitudinal data analysis a random function typically represents a patient, or subject, who is observed at only a small number of randomly distributed points, with nonnegligible measurement error. Nevertheless, essentially the same methods can be used in both these cases, as well as in the vast number of settings that lie between them. How is performance affected by the sampling plan? In this paper we answer that question. We show that if there is a sample of $n$ functions, or subjects, then estimation of eigenvalues is a semiparametric problem, with root-$n$ consistent estimators, even if only a few observations are made of each function, and if each observation is encumbered by noise. However, estimation of eigenfunctions becomes a nonparametric problem when observations are sparse. The optimal convergence rates in this case are those which pertain to more familiar function-estimation settings. We also describe the effects of sampling at regularly spaced points, as opposed to random points. In particular, it is shown that there are often advantages in sampling randomly. However, even in the case of noisy data there is a threshold sampling rate (depending on the number of functions treated) above which the rate of sampling (either randomly or regularly) has negligible impact on estimator performance, no matter whether eigenfunctions or eigenvectors are being estimated.Comment: Published at http://dx.doi.org/10.1214/009053606000000272 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Espace naturel, techniques agraires et végétation ségétale en pays Kassena

Les Kassena, une ethnie sédentaire appartenant au groupe linguistique des Gurunsi, habitent dans une région au sud du Burkina Faso et au nord du Ghana. Leur économie est basée sur l’autosubsistance à partir de la culture du mil et l’élevage du bétail. Avec une saison des pluies de six mois et une pluviométrie de plus de 900 mm, la région offre des conditions favorables à la culture du mil. Cette région est caractérisée par une forte inégalité en ce qui concerne la dispersion de l’habitat. Certaines régions, comme les alentours de la montagne de Tiébélé qui, selon les récits de la tradition orale, est l’ancien centre des Kassena de l’est, connaissent une importante population allant jusqu’à 100 habitants par km/carré. D’autres régions, notamment la vallée du Nazinon, étaient plus ou moins inhabitées jusqu’à ces dernières années. Ceci est probablement dû aux maladies endémiques comme l’onchocercose. Pour les régions les plus peuplées, nous avons cherché à connaître les techniques spécifiques qui ont permis à la population de s’installer et de s’alimenter. Les Kassena maîtrisent un système de culture permanente sur des champs terrassés exigeant beaucoup d’entretien. Ces champs sont soumis à un contrôle social et religieux. De plus, les Kassena cultivent des champs de brousse qui se trouvent souvent dans la plaine et à grande distance des villages. Ces champs de brousse sont cultivés d’une façon plus extensive. Le présent exposé décrit les techniques de l’agriculture en respect des conditions de l’environnement. L’objectif est de mieux comprendre les stratégies économiques et culturelles des cultivateurs de cette région

The design of the HOM-damping cells for the S-band linear collider

Damping cells for the higher order modes are necessary for the S-band linear collider to minimize BBU (Beam-Break-Up). The construction of the damper cells has to take into account the different field geometries of the higher order modes. So two different types of dampers have been designed: a wall slotted an an iris slotted cell. In order to optimize the two types of damping cells with respect to damping strength, impedance matching between coupling system and waveguide dampers and between damping cell and undamped cells and the tuning system, damping cells of both types have been built and examinated

Energy Propagation through the TESLA Channel: Measurements with Two Waveguides Modes

A new method for the determination of S-matrices of devices in multimoded waveguides and first experimental experiences are presented. The theoretical foundations are given. The scattering matrix of a TESLA copper cavity at a frequency above the cut-off of the second waveguide mode has been measured