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Local Networks (local + network)
Selected AbstractsEnhanced synaptic excitation,inhibition ratio in hippocampal interneurons of rats with temporal lobe epilepsyEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2007F. Stief Abstract A common feature of all epileptic syndromes is the repetitive occurrence of pathological patterns of synchronous neuronal activity, usually combined with increased neuronal discharge rates. Inhibitory interneurons of the hippocampal formation control both neuronal synchronization as well as the global level of activity and are therefore of crucial importance for epilepsy. Recent evidence suggests that changes in synaptic inhibition during temporal lobe epilepsy are rather specific, resulting from selective death or alteration of interneurons in specific hippocampal layers. Hence, epilepsy-induced changes have to be analysed separately for different types of interneurons. Here, we focused on GABAergic neurons located at the border between stratum radiatum and stratum lacunosum-moleculare of hippocampal area CA1 (SRL interneurons), which are included in feedforward inhibitory circuits. In chronically epileptic rats at 6,8 months after pilocarpine-induced status epilepticus, frequencies of spontaneous and miniature inhibitory postsynaptic currents were reduced, yielding an almost three-fold increase in excitation,inhibition ratio. Consistently, action potential frequency of SRL interneurons was about two-fold enhanced. Morphological alterations of the interneurons indicate that these functional changes were accompanied by remodelling of the local network, probably resulting in a loss of functional inhibitory synapses without conceivable cell death. Our data indicate a strong increase in activity of interneurons in dendritic layers of the chronically epileptic CA1 region. This alteration may enhance feedforward inhibition and rhythmogenesis and , together with specific changes in other interneurons , contribute to seizure susceptibility and pathological synchronization. [source] Spatiotemporal characterization of interswarm period seismicity in the focal area Nový Kostel (West Bohemia/Vogtland) by a short-term microseismic studyGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2009Martin Häge SUMMARY The West Bohemia/Vogtland region is one of the seismically most interesting areas in Europe because of its swarm-like occurrence of seismicity. The installation of the local West Bohemian seismological network (WEBNET) has made the recording of small magnitude seismicity (detection threshold ML,,0.5) possible. We investigated if microseismicity exists below the detection threshold of WEBNET. A microseismic field campaign was carried out in the focal area Nový Kostel. The measurement was performed with three small arrays lasting for 6 d in a seismically quiet, interswarm period. We were able to detect and locate 13 microearthquakes in the magnitude range ,1.5 ,ML,,0.1 and achieved a detection threshold about one magnitude lower than the local network. A relative location suggests that the recorded seismicity is rather related to a specific fault segment than randomly distributed. The determined fault zone is aligned NW,SW and confirms the viability of mapping active faults with short-term measurements. The results demonstrate that a linear extrapolation of the b -value, determined by the network bulletin, down to ML=,0.5 fits well with the amount of our recorded events. [source] Analysis of the 2002 May earthquake sequence in the central Pyrenees, consequences for the evaluation of the seismic risk at Lourdes, FranceGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2004Noalwenn Dubos SUMMARY Three earthquakes of magnitudes 4.6, 4.3 and 3.7 occurred in 2002 May at two locations 20 km from the pilgrimage city of Lourdes in the French Pyrenees. They were well recorded by the permanent Pyrenean seismic networks, by a temporary local network, as well as by accelerometric stations. In order to understand their tectonic contexts, and to come to a better evaluation of the seismic risk at Lourdes, a detailed analysis of these events is performed. The first two events are located south of Lourdes in an area where only a few earthquakes have occurred up to now. Their focal solutions derived from first-motion polarities indicate reverse faulting, with a N110°E strike consistent with the geological structures. 10 aftershocks were recorded and relocated with respect to the main events, benefiting from the waveform similarity of the various events. This analysis reveals that the two main events concern probably the same fault, the second rupture being in the prolongation of the first one, whereas the other small aftershocks are located on fault segments in the vicinity of the hypocentre of the second event. The third large event, located to the SE of Lourdes, involves a normal mechanism with a N120°E plane parallel to the main geological structures. It occurred in a region of intense activity, including in particular an event of maximum macroseismic intensity IX in 1660. The first two events are at the boundary of a large quiet zone. In order to understand the related structural context, a new crustal tomographic model has been computed. It reveals that this quiet zone coincides with a block of high P -velocity. In contrast, the seismicity appears to be stronger at the northern and eastern boundaries of this block. The accelerometric data of the three main events recorded at Lourdes have been used to estimate the maximum peak ground accelerations in this city if a large event occurred, similar to those which damaged the city in the seventeenth and eighteenth centuries. Horizontal accelerations of 0.25 ± 0.07 g are predicted in the frequency domain 1,5 Hz at the location of the Sanctuary for a magnitude 6 event occurring 10 km away from the city. Taking into account the error bars, these values could in some cases exceed those specified by the building codes in this region. [source] The distribution of file transmission duration in the webINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2004R. Nossenson Abstract It is well known that the distribution of files transmission duration in the Web is heavy-tailed (A practical guide to Heavy Tails: Statistical Techniques and Application. Birkhauser: Boston, 1998; 3,26). This paper attempts to understand the reasons for this phenomenon by isolating the three major factors influencing the transmission duration: file size, network conditions and server load. We present evidence that the transmission-duration distribution (TDD) of the same file from the same server to the same client in the Web is Pareto and therefore heavy tailed. Furthermore, text files transmission delay for a specific client/server pair is not significantly affected by the file sizes: all files transmitted from the same server to the same client have very similar transmission duration distributions, regardless of their size. We use simulations to estimate the impact of network conditions and server load on the TDD. When the server and the client are on the same local network, the TDD of each file is usually Pareto as well (for server files and client requests that are distributed in a realistic way). By examining a wide-area network situation, we conclude that the network conditions do not have a major influence on the heavy-tailed behaviour of TDD. In contrast, the server load is shown to have a significant impact on the high variability of this distribution. Copyright © 2004 John Wiley & Sons, Ltd. [source] Reshaping the State: Administrative Reform and New Public Management in FranceGOVERNANCE, Issue 4 2005ALISTAIR COLE This essay examines the administrative reform process in France since the late 1980s. The key reforms undertaken during this period have sought to delegate greater managerial autonomy to the ministerial field-service level. We undertook semistructured interviews with officials in the field services of three French ministries (Education, Agriculture, and Infrastructure) in the Champagne-Ardennes region, as well as with members of the wider policy communities. The capacity of the field services to adopt a proactive approach to management reform depended on five key variables: internal organizational dynamics; the attitude of the central services to mesolevel autonomy; the degree of institutional receptivity to change; the type of service delivery, and the extent of penetration in local networks. The Infrastructure Ministry was more receptive to management change than either Education or (especially) Agriculture, a receptivity that reflects the institutional diversity of the French administrative system, and that supports new institutionalist arguments. The essay rejects straightforward convergence to the New Policy Management norm. Changes in public management norms require either endogenous discursive shifts or else need to be interpreted in terms of domestic registers that are acceptable or understandable to those charged with implementing reform. [source] The Future of Japanese Manufacturing in the UKJOURNAL OF MANAGEMENT STUDIES, Issue 8 2002Glenn Morgan The expansion of Japanese FDI into the UK manufacturing sector during the 1980s and early 1990s gave rise to the debate on the Japanization of British industry. The paper argues that this debate was constructed from a Western perspective. It did not locate the strategies and structures of Japanese subsidiaries within the broader context of how Japanese multinational corporations were evolving in this period. The necessity to look at these issues from a more global perspective is reinforced by the changes which have occurred since the mid 1990s in the environment for Japanese multinationals. The global economy offers more choices to firms about their location as well as facing them with a more competitive environment. In the Japanese case, this is leading to a growing differentiation between standardized mass production (which can be located in Asia and Eastern Europe) and science,led sectors of industrial production (which necessitate location near to centres of research and development expertise in the USA and Europe). This means that Japanese firms are reconsidering the strategy and structure of their subsidiaries in the UK. Standardized mass production will only survive in the UK as long as costs can be pushed further down and productivity increased, both of which are difficult conditions to meet given possibilities elsewhere in the world for cheap mass production. The growing area of investment will be in science,based manufacturing, though here the UK will be competing against the USA and Germany for Japanese investment. Here, however, the organizational and management characteristics of Japanese subsidiaries will make the necessary connections with local managers and local networks of expertise difficult to achieve. Thus Japanese subsidiaries in the UK are in a period of prolonged uncertainty about their role in the future. These changes open up the necessity for a new agenda of research which goes beyond the Japanization approach and is concerned with the organization and management of Japanese multinationals in an era of global competition. [source] Nonergodic Corruption Dynamics (or, Why Do Some Regions within a Country Become More Corrupt than Others?)JOURNAL OF PUBLIC ECONOMIC THEORY, Issue 2 2006RANDAL J. VERBRUGGE Two key aspects of corruption are strategic complementarity (the greater the prevailing level of corruption, the more likely is a particular agent to engage in it) and localized interactions (officials typically interact repeatedly with a small group of other officials, their colleagues). This paper builds a simple model with these two features, which studies the evolution of corruption. Over time, local networks of corruption (or honest behavior) endogenously emerge, and otherwise identical regions can end up with divergent corruption levels. Anti-corruption policies are studied. [source] Erratum: Three-dimensional spatial interpolation of surface meteorological observations from high-resolution local networks.METEOROLOGICAL APPLICATIONS, Issue 4 20082008; 15:3 33, Cristian Lussana, Francesco Uboldi, Marta Salvati Journal of Meteorological Applications The original article to which this Erratum refers was published in Journal of Meteorological Applications, 2008; 15:3 331,345 [source] Three-dimensional spatial interpolation of surface meteorological observations from high-resolution local networksMETEOROLOGICAL APPLICATIONS, Issue 3 2008Francesco Uboldi Abstract An objective analysis technique is applied to a local, high-resolution meteorological observation network in the presence of complex topography. The choice of optimal interpolation (OI) makes it possible to implement a standard spatial interpolation algorithm efficiently. At the same time OI constitutes a basis to develop, in perspective, a full multivariate data assimilation scheme. In the absence of a background model field, a simple and effective de-trending procedure is implemented. Three-dimensional correlation functions are used to account for the orographic distribution of observing stations. Minimum-scale correlation parameters are estimated by means of the integral data influence (IDI) field. Hourly analysis fields of temperature and relative humidity are routinely produced at the Regional Weather Service of Lombardia. The analysis maps show significant informational content even in the presence of strong gradients and infrequent meteorological situations. Quantitative evaluation of the analysis fields is performed by systematically computing their cross validation (CV) scores and by estimating the analysis bias. Further developments concern the implementation of an automatic quality control procedure and the improvement of error covariance estimation. Copyright © 2008 Royal Meteorological Society [source] Postnatal development of synaptic transmission in local networks of L5A pyramidal neurons in rat somatosensory cortexTHE JOURNAL OF PHYSIOLOGY, Issue 1 2007Andreas Frick The probability of synaptic transmitter release determines the spread of excitation and the possible range of computations at unitary connections. To investigate whether synaptic properties between neocortical pyramidal neurons change during the assembly period of cortical circuits, whole-cell voltage recordings were made simultaneously from two layer 5A (L5A) pyramidal neurons within the cortical columns of rat barrel cortex. We found that synaptic transmission between L5A pyramidal neurons is very reliable between 2 and 3 weeks of postnatal development with a mean unitary EPSP amplitude of ,1.2 mV, but becomes less efficient and fails more frequently in the more mature cortex of ,4 weeks of age with a mean unitary EPSP amplitude of 0.65 mV. Coefficient of variation and failure rate increase as the unitary EPSP amplitude decreases during development. The paired-pulse ratio (PPR) of synaptic efficacy at 10 Hz changes from 0.7 to 1.04. Despite the overall increase in PPR, short-term plasticity displays a large variability at 4 weeks, ranging from strong depression to strong facilitation (PPR, range 0.6,2.1), suggesting the potential for use-dependent modifications at this intracortical synapse. In conclusion, the transmitter release probability at the L5A,L5A connection is developmentally regulated in such a way that in juvenile animals excitation by single action potentials is efficiently transmitted, whereas in the more mature cortex synapses might be endowed with a diversity of filtering characteristics. [source] Regulating Public Transit Networks: How do Urban-Intercity Diversification and Speed-up Measures Affect Firms' Cost Performance?ANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 2 2004Giovanni Fraquelli In this study we estimate a translogarithmic variable cost function to assess the behaviour of returns to scale and the impact of network characteristics. The analysis is based on a sample of 45 Italian municipal companies observed from 1996 to 1998 and including both specialized and mixed transit operators. Results confirm previous evidence on the existence of natural monopoly in the industry and support a regulation introducing competitive tenders to access to the market. In addition, we provide insights about the advantages associated with urban-intercity diversification and with the improvement of network commercial speed. Cost benefits can then be achieved by promoting mergers between neighbouring firms, so as to create new companies operating on integrated local networks and supplying in combination urban and intercity public transport. Implications of such a strategy for the design of tender mechanisms are also underlined, together with the need for a regulatory policy which takes more care of speed-up measures. [source] Organization, Management and Delegation in the French Water IndustryANNALS OF PUBLIC AND COOPERATIVE ECONOMICS, Issue 4 2001Jihad C. Elnaboulsi The water industry is largely a natural monopoly. Water distribution and sewerage services are characterized by networks and its natural monopoly derives from the established local networks of drinking water and sewers: they are capital intensive with sunk costs and increasing returns to scale. In France, local communities have a local requirement of providing public services under optimum conditions in terms of techniques and cost-effectiveness, and subject to respect different kind of standards in terms of water quality and level of services. They are responsible for producing and distributing drinking water, and collecting and treating wastewater. Furthermore, the French water utilities are required to be financially self-sufficient. Rate-setting varies across regions and local territories due to a variety of organizational features of services and availability of water resources. The management of these local public services can be public or private: local governments have the right, by the constitution, to delegate water service management to private companies which operate under the oversight of local municipal authorities. Today, nearly 80 per cent of the French population receive private distributed water. Different reasons are responsible for the poor performance and low productivity of most French public water utilities: technical and operational, commercial and financial, human and institutional, and environmental. Thus, many water public utilities have looked for alternative ways to provide water and sanitation services more efficiently, to improve both operational and investment efficiency, and to attract private finance. The purpose of this paper is to present the French organizational system of providing drinking water services, and collecting and treating wastewater services: legal aspects, contracts of delegation, and competition. [source] The settlement patterns of north-eastern and south-eastern Arabia in late antiquityARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 2 2009Michel Mouton The east Arabian settlements in antiquity were never large urban sites. However, they were the main centres of the communities that inhabited that area, interfacing between the nomadic and sedentary societies. A study of the distribution and characteristics of these sites reveals different, complementary functions. They were organized in local networks forming the essential structure of the settlement pattern and delineating the territories of communities having their own political identity. [source] | |||||||||||||||||||