902 resultados para Information storage and retrieval systems -- Geography
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This paper studies the determinants of school choice, focusing on the role of information. Weconsider how parents' search efforts and their capacity to process information (i.e., tocorrectly assess schools) affect the quality of the schools they choose for their children. Usinga novel dataset, we are able to identify parents' awareness of schools in their neighborhoodand measure their capacity to rank the quality of the school with respect to the officialrankings. We find that parents education and wealth are important factors in determiningtheir level of school awareness and information gathering. Moreover, these search effortshave important consequences in terms of the quality of school choice.
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\documentstyle[portada,11pt]{article}This paper shows that the presence of private information in aneconomy can be a source of market incompleteness even when it is feasibleto issue a set of securities that completely eliminates the informationalasymmetries in equilibrium. We analyze a simple security design model in which avolume maximizing futures exchange chooses not only the characteristics ofeach individual contract but also the number of contracts. Agents have rationalexpectations and differ in information, endowments and, possibly, attitudestoward risk. The emergence of complete or incomplete markets in equilibriumdepends on whether the {\it adverse selection effect} is stronger or weakerthan the {\it Hirshleifer effect}, as new securitiesare issued and prices reveal more information. When the Hirshleifer effectdominates, the exchange chooses an incomplete set of financial contracts, andthe equilibrium price is partially revealing.
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Before firms decide whether to enter a new market or not, they havethe opportunity to buy information about several variables that might affectthe profitability of this market. Our model differs from the existing literatureon endogenous information acquisition in two respects: (1) there is uncertaintyabout more than one variable, and (2) information is acquired secretly. Whenthe cost of acquiring information is small, entry decisions will be as ifthere was perfect information. Equilibria where each firm acquires only asmall amount of information are more robust than the socially undesirableequilibria where all firms gather all information. Examples illustrate theimportance of assumptions (1) and (2).
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This article analyzes how mandatory accounting disclosure is grounded on differentrationales for private and public companies. It also explores technological changes, such ascomputerised databases and the Internet, which have recently made disclosure of companyaccounts by small companies potentially less costly and more valuable, thanks to electronicfiling and universal online access to credit information systems. These recent developmentsfavour policies that would expand the scope of mandatory publication for small companies incountries where it is voluntary. They also encourage policies to reduce the costs and enhancethe value of disclosure through administrative reforms of filing, archive and retrieval systems.Survey and registry evidence on how the information in the accounts is valued and used bycompanies is consistent with these claims about the evolution of the tradeoff of costs andbenefits that should guide policy in this area.
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Neuron-astrocyte reciprocal communication at synapses has emerged as a novel signalling pathway in brain function. Astrocytes sense the level of synaptic activity and, in turn, influence its efficacy through the regulated release of 'gliotransmitters' such as glutamate, ATP or D-serine. A calcium-dependent exocytosis is proposed to drive the release of gliotransmitters but its existence is still debated. Over the last years, we have been studying the molecular determinants governing D-serine release from glia using different approaches. Using a novel bioassay for D-serine, we have been able to show that D-serine release occurs mainly through a calcium- and SNARE proteindependent mechanism just supporting the idea that this amino acid is released by exocytosis from glia. We next have pursued our exploration by confocal imaging and tracking of the exocytotic routes for Dserine- mediated gliotransmission and have shown that D-serine releasable pools are confined to synaptobrevin2/cellubrevin-bearing vesicles. To shed light onto the mechanisms controlling the storage and the release of gliotransmitters and namely D-serine, we have developed a new method for the immunoisolation of synaptobrevin 2- positive vesicles from rat cortical astrocytes in culture while preserving their content in gliotransmitters. The purified organelles are clear round shape vesicles of excellent purity with homogeneous size (40 nm) as judged by electron microscopy. Immunoblotting analysis revealed that isolated vesicles contain most of the major proteins already described for neuron-derived vesicles like synaptic vesicle protein 2 (SV2) and the proton pump H?-ATPase. In addition, we have analyzed the content for various amino acids of these vesicles by means of chiral capillary electrophoresis coupled to laser-induced fluorescence detection. The purified vesicles contain large amount of D-serine. We also detect peaks corresponding to unidentified compounds that may correspond to others amino acids. Postembedding immunogold labelling of the rat neocortex further revealed the expression of D-serine in astrocytes processes contacting excitatory synapses. Finally, we have examined the uptake properties for Dserine and glutamate inside the isolated glial vesicles. Our results provide significant support for the existence of an uptake system for D-serine in secretory glial vesicles and for the storage of chemical substances like D-serine and glutamate. 11th International Congress on Amino Acids, Peptides and Proteins 763 123
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Organizations often face the challenge of communicating their strategiesto local decision makers. The difficulty presents itself in finding away to measure performance wich meaningfully conveys how to implement theorganization's strategy at local levels. I show that organizations solvethis communication problem by combining performance measures in such away that performance gains come closest to mimicking value-added asdefined by the organization's strategy. I further show how organizationsrebalance performance measures in response to changes in their strategies.Applications to the design of performance metrics, gaming, and divisionalperformance evaluation are considered. The paper also suggests severalempirical ways to evaluate the practical importance of the communicationrole of measurement systems.
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Can we reconcile the predictions of the altruism model of the familywith the evidence on intervivos transfers in the US? This paper expandsthe altruism model by introducing e ?ort of the child and by relaxingthe assumption of perfect information of the parent about the labormarket opportunities of the child. First, I solve and simulate a modelof altruism under imperfect information. Second, I use cross-sectionaldata to test a prediction of the model: Are parental transfers especiallyresponsive to the income variations of children who are very attached tothe labor market? The results suggest that imperfect information accountsfor several patterns of intergenerational transfers in the US.
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In some markets, such as the market for drugs or for financial services, sellers have better information than buyersregarding the matching between the buyer's needs and the good's actual characteristics. Depending on the market structure,this may lead to conflicts of interest and/or the underprovision of information by the seller. This paper studies this issuein the market for financial services. The analysis presents a new model of competition between banks, as banks' pricecompetition influences the ensuing incentives for truthful information revelation. We compare two different firm structures,specialized banking, where financial institutions provide a unique financial product, and one-stop banking, where a financialinstitution is able to provide several financial products which are horizontally differentiated. We show first that, althoughconflicts of interest may prevent information disclosure under monopoly, competition forces full information provision forsufficiently high reputation costs. Second, in the presence of market power, one-stop banks will use information strategicallyto increase product differentiation and therefore will always provide reliable information and charge higher rices thanspecialized banks, thus providing a new justification for the creation of one-stop banks. Finally, we show that, ifindependent financial advisers are able to provide reliable information, this increases product differentiation and thereforemarket power, so that it is in the interest of financial intermediaries to promote external independent financial advice.
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Can we reconcile the predictions of the altruism model of the family withthe evidence on parental monetary transfers in the US? This paper providesa new assessment of this question. I expand the altruism model by introducingeffort of the child and by relaxing the assumption of perfect informationof the parent about the labor market opportunities of the child. First,I solve and simulate a model of altruism and labor supply under imperfectinformation. Second, I use cross-sectional data to test the following prediction of the model: Are parental transfers especially responsive tothe income variations of children who are very attached to the labor market? The results of the analysis suggest that imperfect informationaccounts for many of the patterns of intergenerational transfers in theUS.
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Els objectius d'aquest informe són realitzar un estudi de la tècnica en la digitalització, l'emmagatzematge i l'accés a les tesis doctorals electròniques, per tal de fer una proposta d’organització al Consorci de Biblioteques Universitàries de Catalunya (CBUC). Actualment, tot i que existeixen diverses iniciatives a Europa, és als EUA on la digitalització de tesis doctorals s’ha desenvolupat més amb la creació de la Networked Digital Library for Theses and Dissertation (NDLTD), i ha estat qui ha definit els estàndards en aquest camp. En el següent informe es planteja i es recomana al CBUC l’adhesió institucional a l’NDLTD per poder gaudir de la seva experiència.
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There is no doubt about the necessity of protecting digital communication: Citizens are entrusting their most confidential and sensitive data to digital processing and communication, and so do governments, corporations, and armed forces. Digital communication networks are also an integral component of many critical infrastructures we are seriously depending on in our daily lives. Transportation services, financial services, energy grids, food production and distribution networks are only a few examples of such infrastructures. Protecting digital communication means protecting confidentiality and integrity by encrypting and authenticating its contents. But most digital communication is not secure today. Nevertheless, some of the most ardent problems could be solved with a more stringent use of current cryptographic technologies. Quite surprisingly, a new cryptographic primitive emerges from the ap-plication of quantum mechanics to information and communication theory: Quantum Key Distribution. QKD is difficult to understand, it is complex, technically challenging, and costly-yet it enables two parties to share a secret key for use in any subsequent cryptographic task, with an unprecedented long-term security. It is disputed, whether technically and economically fea-sible applications can be found. Our vision is, that despite technical difficulty and inherent limitations, Quantum Key Distribution has a great potential and fits well with other cryptographic primitives, enabling the development of highly secure new applications and services. In this thesis we take a structured approach to analyze the practical applicability of QKD and display several use cases of different complexity, for which it can be a technology of choice, either because of its unique forward security features, or because of its practicability.
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Podeu consultar la versió en castellà a http://hdl.handle.net/2445/8955