856 resultados para open waveguides


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Ultracold gases in ring geometries hold promise for significant improvements of gyroscopic sensitivity. Recent experiments have realized atomic and molecular storage rings with radii in the centimeter range, sizes whose practical use in inertial sensors requires velocities significantly in excess of typical recoil velocities. We use a combination of analytical and numerical techniques to study the coherent acceleration of matter waves in circular waveguides, with particular emphasis on its impact on single-mode propagation. In the simplest case we find that single-mode propagation is best maintained by the application of time-dependent acceleration force with the temporal profile of a Blackmann pulse. We also assess the impact of classical noise on the acceleration process.

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Background: Home-management of malaria (HMM) strategy improves early access of anti-malarial medicines to high-risk groups in remote areas of sub-Saharan Africa. However, limited data are available on the effectiveness of using artemisinin-based combination therapy (ACT) within the HMM strategy. The aim of this study was to assess the effectiveness of artemether-lumefantrine (AL), presently the most favoured ACT in Africa, in under-five children with uncomplicated Plasmodium falciparum malaria in Tanzania, when provided by community health workers (CHWs) and administered unsupervised by parents or guardians at home. Methods: An open label, single arm prospective study was conducted in two rural villages with high malaria transmission in Kibaha District, Tanzania. Children presenting to CHWs with uncomplicated fever and a positive rapid malaria diagnostic test (RDT) were provisionally enrolled and provided AL for unsupervised treatment at home. Patients with microscopy confirmed P. falciparum parasitaemia were definitely enrolled and reviewed weekly by the CHWs during 42 days. Primary outcome measure was PCR corrected parasitological cure rate by day 42, as estimated by Kaplan-Meier survival analysis. This trial is registered with ClinicalTrials.gov, number NCT00454961. Results: A total of 244 febrile children were enrolled between March-August 2007. Two patients were lost to follow up on day 14, and one patient withdrew consent on day 21. Some 141/241 (58.5%) patients had recurrent infection during follow-up, of whom 14 had recrudescence. The PCR corrected cure rate by day 42 was 93.0% (95% CI 88.3%-95.9%). The median lumefantrine concentration was statistically significantly lower in patients with recrudescence (97 ng/mL [IQR 0-234]; n = 10) compared with reinfections (205 ng/mL [114-390]; n = 92), or no parasite reappearance (217 [121-374] ng/mL; n = 70; p <= 0.046). Conclusions: Provision of AL by CHWs for unsupervised malaria treatment at home was highly effective, which provides evidence base for scaling-up implementation of HMM with AL in Tanzania.

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Agent-oriented software engineering (AOSE) is a promising approach to developing applications for dynamic open systems. If well developed, these applications can be opportunistic, taking advantage of services implemented by other developers at appropriate times. However, methodologies are needed to aid the development of systems that are both flexible enough to be opportunistic and tightly defined by the application requirements. In this paper, we investigate how developers can choose the coordination mechanisms of agents so that the agents will best fulfil application requirements in an open system.

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The open provenance architecture (OPA) approach to the challenge was distinct in several regards. In particular, it is based on an open, well-defined data model and architecture, allowing different components of the challenge workflow to independently record documentation, and for the workflow to be executed in any environment. Another noticeable feature is that we distinguish between the data recorded about what has occurred, emphprocess documentation, and the emphprovenance of a data item, which is all that caused the data item to be as it is and is obtained as the result of a query over process documentation. This distinction allows us to tailor the system to separately best address the requirements of recording and querying documentation. Other notable features include the explicit recording of causal relationships between both events and data items, an interaction-based world model, intensional definition of data items in queries rather than relying on explicit naming mechanisms, and emphstyling of documentation to support non-functional application requirements such as reducing storage costs or ensuring privacy of data. In this paper we describe how each of these features aid us in answering the challenge provenance queries.

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The Open Provenance Model is a model of provenance that is designed to meet the following requirements: (1) To allow provenance information to be exchanged between systems, by means of a compatibility layer based on a shared provenance model. (2) To allow developers to build and share tools that operate on such a provenance model. (3) To define provenance in a precise, technology-agnostic manner. (4) To support a digital representation of provenance for any 'thing', whether produced by computer systems or not. (5) To allow multiple levels of description to coexist. (6) To define a core set of rules that identify the valid inferences that can be made on provenance representation. This document contains the specification of the Open Provenance Model (v1.1) resulting from a community-effort to achieve inter-operability in the Provenance Challenge series.

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A description of a data item's provenance can be provided in dierent forms, and which form is best depends on the intended use of that description. Because of this, dierent communities have made quite distinct underlying assumptions in their models for electronically representing provenance. Approaches deriving from the library and archiving communities emphasise agreed vocabulary by which resources can be described and, in particular, assert their attribution (who created the resource, who modied it, where it was stored etc.) The primary purpose here is to provide intuitive metadata by which users can search for and index resources. In comparison, models for representing the results of scientific workflows have been developed with the assumption that each event or piece of intermediary data in a process' execution can and should be documented, to give a full account of the experiment undertaken. These occurrences are connected together by stating where one derived from, triggered, or otherwise caused another, and so form a causal graph. Mapping between the two approaches would be benecial in integrating systems and exploiting the strengths of each. In this paper, we specify such a mapping between Dublin Core and the Open Provenance Model. We further explain the technical issues to overcome and the rationale behind the approach, to allow the same method to apply in mapping similar schemes.

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Just about every time I open a journal or read a blog online, I see something about e-books saving newspapers and magazines. Both magazines and newspapers–and really all scholalry communication–are going the way of all flesh, we’re told, but e-book reading may provide a stay of execution, however short that may be. It got me to thinking if there might be something else that would provide a similarDies Irae proroguement for scholarly communication in general. That’s when it occurred to me it could well be open access (OA), or at least as I envision it here.

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Os Sistemas de Informação Geográfica (SIG) são construídos, especificamente, para armazenar, analisar e manipular dados geográficos, ou seja, dados que representam objetos e fenômenos do mundo real, cuja localização em relação à superfície da Terra seja considerada. A interoperabilidade desses sistemas, que constitui-se na capacidade de compartilhar e trocar informações e processos entre ambientes computacionais heterogêneos, se faz necessária, pois, devido ao elevado custo de aquisição dos dados geográficos, as comunidades de informação precisam compartilhar dados de fontes existentes, sem a necessidade de fazer conversões. Porém, pela complexidade e incompatibilidades de representação, de estrutura e de semântica das informações geográficas, a maioria dos softwares de SIG, hoje, não são interoperáveis. Existe também, além do problema da não interoperabilidade, uma crescente preocupação com relação à qualidade e à integridade espacial dos dados geográficos. Contudo, alguns modelos conceituais de dados geográficos e os softwares de SIG não oferecem, ainda, os meios adequados para representar e garantir a integridade espacial das informações. As restrições de integridade definidas durante a fase de projeto conceitual, normalmente, são implementadas durante o projeto físico, seja de forma implícita ou explícita, podendo ser incorporadas diretamente no modelo de implementação do SIG, de forma que o usuário da aplicação apenas mencione a regra e o sistema a implemente e a garanta automaticamente.Este trabalho de pesquisa propõe uma extensão ao Modelo Abstrato OpenGIS, modelo este que deve ser um padrão de interoperabilidade de software para SIG. A extensão proposta incorpora ao mesmo um subconjunto de tipos de restrição espacial, buscando com isso oferecer melhor suporte às regras da realidade geográfica expressáveis na modelagem conceitual do sistema.

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This paper presents an overview of the Brazilian macroeconomy by analyzing the evolution of some specific time series. The presentation is made through a sequence of graphs. Several remarkable historical points and open questions come up in the data. These include, among others, the drop in output growth as of 1980, the clear shift from investments to government current expenditures which started in the beginning of the 80s, the notable way how money, prices and exchange rate correlate in an environment of permanently high inflation, the historical coexistence of high rates of growth and high rates of inflation, as well as the drastic increase of the velocity of circulation of money between the 70s and the mid-90s. It is also shown that, although net external liabilities have increased substantially in current dollars after the Real Plan, its ratio with respect to exports in 2004 is practically the same as the one existing in 1986; and that residents in Brazil, in average, owed two more months of their final income (GNP) to abroad between 1995-2004 than they did between 1990 and 1994. Variance decompositions show that money has been important to explain prices, but not output (GDP).

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This paper provides an examination of the emergence of open business models — entrepreneurial strategies that take advantage of the ease of digital reproduction to distribute free content, while earning money from the sale of related products and services. Locating the origins of open business in the open source software phenomenon, the authors suggest that the business strategies innovated there have broader economic relevance. Through a case study of the tecnobrega music scene in Belém, the paper illustrates how open business models can be applied to the production of cultural materials more generally

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Desde que Chesbrough (2003) cunhou o termo inovação aberta, o conceito tem atraído uma atenção crescente tanto no meio acadêmico quanto no mundo empresarial. Apesar dos esforços crescentes em explorar práticas de inovação aberta, muitas perguntas permanecem sem resposta. A pesquisa acadêmica expandiu o foco abordando o tema de forma bastante ampla como gestão da inovação, estratégia empresarial, comportamento organizacional e políticas públicas. Ao mesmo tempo, gestores também têm explorado na prática o conceito de inovação aberta de formas muito diversificadas. Levando em conta a variabilidade das práticas de inovação aberta, este estudo visa fornecer microfundamentos para a inovação aberta, adotando a teoria de effectuation. A teoria de effectuation foi originalmente desenvolvida no campo da pesquisa sobre empreendedorismo. Pode ser definida como um conjunto de princípios de tomada de decisão que pode ser ensinado e aprendido, formando uma lógica global empregada por empreendedores com expertise frente a situações de incerteza durante a criação de novos empreendimentos e novos mercados (SARASVATHY, 2001; 2008). Nós demostramos que a teoria effectuation tem a consistência para fornecer uma contribuição sólida no nível micro das práticas de inovação aberta. Neste trabalho, realizamos um estudo de caso extensivo sobre uma organização de gestão da inovação aberta destinada a promover a colaboração entre Brasil e Suécia. Examinamos os processos de tomada de decisão de 13 especialistas em R&D e gerentes de inovação que juntos representam oito diferentes entidades envolvidas em sua criação. Como resultado de nossa pesquisa, identificamos e descrevemos a metodologia de tomada de decisão utilizada pelos gestores de inovação envolvidos na criação de uma organização dedicada à gestão da inovação aberta. As percepções frutos da pesquisa realizada nos permitiu desenvolver um quadro de tomada de decisão com base nas teorias de effectuation e inovação aberta, capaz de apoiar gestores na criação de novas organizações dedicadas à gestão da inovação aberta.