635 research outputs found
Judentum im Wandel. Eine Diskurs- und Wissensgemeinschaft
Das Jahr 2016 wird im Bewusstsein der Schweizer Juden und JĂŒdinnen als JubilĂ€um der Emanzipation vor 150 Jahren gefeiert. 1866 wurde den Juden durch eine Volksabstimmung die freie Niederlassung in der ganzen Schweiz gewĂ€hrt. 1874 folgte im Rahmen einer Verfassungsrevision auch die GewĂ€hrung der allgemeinen Kultusfreiheit. Ein Blick in die Geschichte des Schweizer Judentums verweist auch auf dessen Gegenwart, die von vielerlei Facetten und IdentitĂ€ten und einem Wandel der Traditionen geprĂ€gt ist
Testing the isotropy of high energy cosmic rays using spherical needlets
For many decades, ultrahigh energy charged particles of unknown origin that
can be observed from the ground have been a puzzle for particle physicists and
astrophysicists. As an attempt to discriminate among several possible
production scenarios, astrophysicists try to test the statistical isotropy of
the directions of arrival of these cosmic rays. At the highest energies, they
are supposed to point toward their sources with good accuracy. However, the
observations are so rare that testing the distribution of such samples of
directional data on the sphere is nontrivial. In this paper, we choose a
nonparametric framework that makes weak hypotheses on the alternative
distributions and allows in turn to detect various and possibly unexpected
forms of anisotropy. We explore two particular procedures. Both are derived
from fitting the empirical distribution with wavelet expansions of densities.
We use the wavelet frame introduced by [SIAM J. Math. Anal. 38 (2006b) 574-594
(electronic)], the so-called needlets. The expansions are truncated at scale
indices no larger than some , and the distances between
those estimates and the null density are computed. One family of tests (called
Multiple) is based on the idea of testing the distance from the null for each
choice of , whereas the so-called PlugIn approach is
based on the single full expansion, but with thresholded wavelet
coefficients. We describe the practical implementation of these two procedures
and compare them to other methods in the literature. As alternatives to
isotropy, we consider both very simple toy models and more realistic
nonisotropic models based on Physics-inspired simulations. The Monte Carlo
study shows good performance of the Multiple test, even at moderate sample
size, for a wide sample of alternative hypotheses and for different choices of
the parameter . On the 69 most energetic events published by the
Pierre Auger Collaboration, the needlet-based procedures suggest statistical
evidence for anisotropy. Using several values for the parameters of the
methods, our procedures yield -values below 1%, but with uncontrolled
multiplicity issues. The flexibility of this method and the possibility to
modify it to take into account a large variety of extensions of the problem
make it an interesting option for future investigation of the origin of
ultrahigh energy cosmic rays.Comment: Published in at http://dx.doi.org/10.1214/12-AOAS619 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The spatial selection of heterogeneous firms
The aim of this paper is to study the spatial selection of firms once it is recognized that heterogeneous firms typically choose different locations in respond to market integration of regions having different sizes. Specifically, we show that decreasing trade costs leads to the gradual agglomeration of efficient firms in the large region because these firms are able to survive in a more competitive environment. In contrast, high-cost firms seek protection against competition from the efficient firms by establishing themselves in the small region. However, when the spatial separation of markets ceases to be a sufficient protection against competition from the low-cost firms, high-cost firms also choose to set up in the larger market where they have access to a bigger pool of consumers. This leads to the following prediction: the relationship between economic integration and interregional productivity differences first increases and then decreases with market integration.Firm heterogeneity, Spatial selection, Trade liberalization
A statistical approach for array CGH data analysis
BACKGROUND: Microarray-CGH experiments are used to detect and map chromosomal imbalances, by hybridizing targets of genomic DNA from a test and a reference sample to sequences immobilized on a slide. These probes are genomic DNA sequences (BACs) that are mapped on the genome. The signal has a spatial coherence that can be handled by specific statistical tools. Segmentation methods seem to be a natural framework for this purpose. A CGH profile can be viewed as a succession of segments that represent homogeneous regions in the genome whose BACs share the same relative copy number on average. We model a CGH profile by a random Gaussian process whose distribution parameters are affected by abrupt changes at unknown coordinates. Two major problems arise : to determine which parameters are affected by the abrupt changes (the mean and the variance, or the mean only), and the selection of the number of segments in the profile. RESULTS: We demonstrate that existing methods for estimating the number of segments are not well adapted in the case of array CGH data, and we propose an adaptive criterion that detects previously mapped chromosomal aberrations. The performances of this method are discussed based on simulations and publicly available data sets. Then we discuss the choice of modeling for array CGH data and show that the model with a homogeneous variance is adapted to this context. CONCLUSIONS: Array CGH data analysis is an emerging field that needs appropriate statistical tools. Process segmentation and model selection provide a theoretical framework that allows precise biological interpretations. Adaptive methods for model selection give promising results concerning the estimation of the number of altered regions on the genome
No trade, one-way or two-way trade?
We study how the level of trade costs and the intensity of competition can explain the existence of two-way, one-way or no trade within the same industry. As trade costs decrease from very high to very low values, the economy moves from autarky to a regime of two-way trade, through a regime of one-way trade from the larger to the smaller country. Trade is less likely when the economy gets more competitive. Finally once capital is mobile across countries, the market delivers an outcome in which capital is too much concentrated in the large country.Trade regime, Country asymmetry, Capital mobility
Les ressources exploitées par les élÚves pour agir dans un format pédagogique en atelier : Une étude empirique lors de leçons de musculation en Education Physique et Sportive
Cette Ă©tude sâintĂ©resse aux ressources situationnelles que les Ă©lĂšves utilisent lors de leçons dâĂ©ducation physique en musculation conçues dans un format pĂ©dagogique en ateliers, en explorant les liens entre lâarrangement spatial des ateliers, la nature des objets matĂ©riels prĂ©sents dans chaque atelier et les interactions entre les Ă©lĂšves. Elle a Ă©tĂ© conduite selon le cadre thĂ©orique et mĂ©thodologique du « cours dâaction ». Deux types de donnĂ©es ont Ă©tĂ© recueillis : (a) des donnĂ©es dâenregistrement audio et vidĂ©o des Ă©lĂšves en classe et (b) des donnĂ©es de verbalisations lors dâentretiens dâautoconfrontation. Les rĂ©sultats rĂ©vĂšlent chez les Ă©lĂšves rĂ©alisant les exercices (a) lâexistence de quatre prĂ©occupations typiques dirigĂ©es vers des ateliers distants associĂ©es Ă trois actions typiques dans lâactivitĂ© des Ă©lĂšves, et (b) des relations entre ces actions typiques et le type dâappareil de musculation prĂ©sent dans lâatelier. Ces rĂ©sultats accrĂ©ditent lâidĂ©e de la classe comme un systĂšme Ă©co-social.This study focused on student interactions during resistance-training lessons in Physical Education classes organized according to the educational workshop format, and contributes to empirical studies investigating the relationships between the spatial arrangement of the workshops, the material objects present in each workshop, and the student interactions to determine the situational resources that the students used for acting in this educational format. It was carried out within the theoretical and methodological framework of the âcourse of actionâ. Two categories of data were collected: (a) classroom audio and video recordings during lessons and (b) individual self-confrontation interviews. Our results regarding the âweight-trainersâ demonstrated (a) four typical concerns directed toward other workshops that were expressed according to three typical modes and (b) relationships between these typical modes and the type of weight machine in the workshop. The results support the concept of the class as an ecosocial system
A mixture model for random graphs
{The Erdos-RĂ©nyi model of a network is simple and possesses many explicit expressions for average and asymptotic properties, but it does not fit well to real-word networks. The vertices of these networks are often structured in \textit{prior} unknown clusters (functionally related proteins or social communities) with different connectivity properties. We define a generalization of the Erdos-RĂ©nyi model called ERMG for Erdos-RĂ©nyi Mixtures for Graphs. This new model is based on mixture distributions. We give some of its properties, an algorithm to estimate its parameters and apply this method to uncover the modular structure of a network of enzymatic reactions
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