Many studies have shown that academic achievement is highly correlated with social class. Few, however, have attempted to explain exactly how the school helps to reinforce the class structure of the society. In this article Dr. Rist reports the results of an observational study of one class

Il est possible d’inférer, à partir de l’information archéologique, représentée par la distribution spatio-temporelle des sites archéologiques et des dates 14C correspondantes, la distribution géographique, la cinétique et les effectifs des populations de chasseurs-collecteurs, du Paléolithique supérieur en Europe. A partir d’une base de données concentrée sur l’Europe de l’Ouest (N 1450 sites, 2800 dates C14), deux études récentes ont fournies, l’une la reconstitution sur la carte du processus d’expansion-contraction des hommes modernes et des néanderthaliens (37.5-27.5 Ka BP), l’autre la reconstitution de la démodynamique des chasseurs-collecteurs au Paléolithique supérieur (40-11.5 Ka BP). La première étude utilise des techniques de géostatistique, la seconde des techniques d’analyses spatio-temporelles de densités. On se propose d’étendre géographiquement la base de données archéologiques existante à l’Europe de l’Est et d’appliquer ces deux approches à l’ensemble de l’Europe, de l’Atlantique à l’Oural. 1. Responsable scientifique du projet

f : M ! N of CA is null-homotopic if f = dr + rd for some homogeneous morphism r : M ! N of degree-1 of the underlying graded A-modules.

This thesis analyses parliamentary privilege. The privilege is an ancient parliamentary power. All of countries that have democratized or will soon have democratized provide them by own constitution. The purpose of the parliamentary privilege is to permit members of the legislature to speech freely and express their opinion of political position, and not worry about retaliation on the basis of political motives. The Parliament formulates itself its own rules of procedure and maintains the discipline of parliament itself and so on, in order to ensure that the parliament can independently, freely discharge of its duties and perform its functions. Parliamentary privilege, however, is often misunderstood by popular who believes that the privilege is the special protection of all of the elites of society. That is ironic, because privilege was originally produced as a whole of the protection of Parliament, and it protected members of parliament from the elites at that time. It may be said that parliamentary privilege is a special institutional arrangements based on the principles of democracy. Compared with other

This thesis deals with Experimental Channel Characterisation and its performance limits in real propagation environments. This includes recording of the multidimensional wideband channel matrix by using a Multiple-Input Multiple-Output (MIMO) channel sounder and antenna arrays at both sides of the link. High-resolution parameter estimation is finally applied to characterise the channel in terms of Direction of Departure (DoD), Direction of Arrival (DoA), Time Delay of Arrival (TDoA), and complex polarimetric path weights. The quality of these estimates in “real world ” scenarios is degraded by several impairments of the practical antenna arrays and the measurement system used. The resulting estimation quality limits are investigated in detail by simulations and measurements. The entire processing chain is analysed in terms of possible error sources. To this end, measurement system impairments, antenna array calibration errors as well as limitations of the radio channel model applied by the high-resolution parameter estimation procedure are investigated. Moreover, consequences of using these results to deduce and parameterise geometry based channel models are demonstrated. Propagation measurements give us an antenna dependent description of the radio channel. For the

One of the greatest challenges for search engines and other search tools, which are developed to cope with the information overload, is the vocabulary mismatch problem, referring to the fact that different people usually use different vocabularies to describe the same concepts. This problem can first of all lead to unsatisfactory search results, because the keywords in search queries often do not match the indices of search engines – either the queries are too imprecise to describe users ’ actual needs, or, although correctly formulated, the queries simply do not contain the keywords with which authors write their documents. There is therefore a clear need to quickly build a concept structure for each possible topic or knowledge domain of user interest, which includes the most important concepts of a specific knowledge domain and the relationships between the concepts. Such concept structures can serve to standardize vocabularies in various knowledge domains, and help to bridge the vocabulary gap between information users, information creators, and search engines. Since manual approaches often suffer from the problem of low coverage and high expense, this dissertation focuses on corpus based statistical approaches to automatically build domain-

The interactive rendering of three-dimensional geometric models is a research area of big interest in computer graphics. The generation of a fluent animation for complex models, consisting of multiple million primitives, with more than 60 frames per second is a special challenge. Possible applications include ship-, driving- and flight simulators, virtual reality and computer games. Although the performance of common computer graphics hardware has dramatically increased in recent years, the demand for more realism and complexity in common scenes is growing even faster. This dissertation is about one approach for accelerating the rendering of such complex scenes. We take advantage of the fact that the appearance of distant scene parts hardly changes for several successive output images. Those scene parts are replaced by precomputed image-based representations, so-called impostors. Impostors are very fast to render while maintaining the appearance of the scene part as long as the viewer moves within a bounded viewing region, a so-called view cell.

QoS Signalling and Charging in a Multi-service Internet using RSVP Because of the high level of uncertainty about the future traffic mix and the heterogeneous na-ture of Quality of Service (QoS) technologies and service contracts, it is very likely that a future commercial multi-service Internet requires a general service signalling architecture to reliably deliver end-to-end QoS. In this thesis, the suitability of the Resource Reservation Protocol (RSVP) for this purpose is investigated and assessed. The thesis presents the following contri-butions: A flexible QoS signalling architecture is described, based on an extended version of RSVP. A new protocol engine has been designed and implemented, containing a number of de-sign and algorithmic improvements over previous work. This implementation has been used to experimentally verify the technical suitability of RSVP. Additionally, new protocol elements have been developed to allow for flexible charging mechanisms of service invocations. Based on several calculation models for service invocations, these protocol elements are assessed to cover a variety of potential usage cases, namely cost-based pricing, auction-based pricing and advance service invocations. As a result, it is concluded that an extended version of RSVP is

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eingereicht und durch die Fakultät für Elektrotechnik und Informationstechnik am 24.06.2008 angenommen. By inferring the intention of human subjects from signals generated by the cen-tral nervous system (CNS), Brain-Computer Interfaces (BCIs) provide an alterna-tive means of communication for subjects with damages to the peripheral nervous system, e.g., caused by neuro-degenerative diseases such as amyotrophic lateral sclerosis or brain stem stroke. While state-of-the-art BCIs based on non-invasive recording modalities enable elementary communication, more complex tasks, such as the control of a robotic endeffector, remain beyond the feasibility of current sys-tems. In this thesis, it is argued that the primary cause for this limitation is the inadequacy of present algorithms for feature extraction, i.e., of algorithms that aim to extract those characteristics of the data recorded from the CNS providing most information on the BCI-user’s intention. The main contribution of this thesis in addressing this