494 research outputs found

    On the Alexandrov Topology of sub-Lorentzian Manifolds

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    It is commonly known that in Riemannian and sub-Riemannian Geometry, the metric tensor on a manifold defines a distance function. In Lorentzian Geometry, instead of a distance function it provides causal relations and the Lorentzian time-separation function. Both lead to the definition of the Alexandrov topology, which is linked to the property of strong causality of a space-time. We studied three possible ways to define the Alexandrov topology on sub-Lorentzian manifolds, which usually give different topologies, but agree in the Lorentzian case. We investigated their relationships to each other and the manifold's original topology and their link to causality.Comment: 20 page

    Socio-economic conditions for satisfying human needs at low energy use: an international analysis of social provisioning

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    Meeting human needs at sustainable levels of energy use is fundamental for avoiding catastrophic climate change and securing the well-being of all people. In the current political-economic regime, no country does so. Here, we assess which socio-economic conditions might enable societies to satisfy human needs at low energy use, to reconcile human well-being with climate mitigation. Using a novel analytical framework alongside a novel multivariate regression-based moderation approach and data for 106 countries, we analyse how the relationship between energy use and six dimensions of human need satisfaction varies with a wide range of socio-economic factors relevant to the provisioning of goods and services ('provisioning factors'). We find that higher achievements in factors such as income equality, democratic quality, electricity access, and public service quality are linked to greater need satisfaction and lower energy requirements (‘beneficial provisioning factors’). Conversely, higher levels of economic growth and extractivism are associated with lower need satisfaction and greater energy dependence (‘detrimental provisioning factors’). Our results suggest that improving beneficial provisioning factors and abandoning detrimental ones could enable countries to provide sufficient need satisfaction within sustainable levels of energy use. However, as key pillars of the required changes in provisioning run contrary to the dominant political-economic regime, a broader political-economic transformation may be required to prioritise, and organise provisioning for, the satisfaction of human needs at low energy use

    Adaptação do inventário parental “Language Use Inventory (LUI)” para crianças entre 18 e 47 meses para o português europeu : estudo piloto

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    Language acquisition and development takes in account the child’s interaction with the surrounding environment. Daily social interactions with people and communication with others allow the child to acquire language being pragmatics considered a system of rules that support the communicative use of language. Identification and assessment of children at risk for language disorders are crucial in order to carry out an effective early intervention. This study was carried out taking into account first, the relevance of pragmatics as a component of language, and second the lack of assessment tools in Portugal to assess these abilities. Therefore, the aim of this study consists on the translation, adaptation and validation of the inventory “Language Use Inventory” (LUI), to European Portuguese. The LUI is a standardized parent report measure designed to assess pragmatic language development in children within 18- to 47-month-old.Objetivo: A aquisição e o desenvolvimento da linguagem resultam da interação da criança com o meio ambiente. As interações sociais cotidianas com as pessoas e a comunicação com outros permitem que a criança adquira linguagem, sendo a pragmática o sistema de regras que suporta o uso comunicativo da linguagem. A identificação e a avaliação de crianças em risco de desenvolverem transtornos de linguagem são cruciais, tendo em vista a intervenção precoce eficaz. Tendo em vista a relevância da pragmática como componente da linguagem e a escassez, em Portugal, de instrumentos de avaliação da linguagem validados para idades precoces, a finalidade deste estudo consistiu na tradução, adaptação e validação do instrumento Language Use Inventory (LUI), para o português europeu. O LUI é um inventário parental que avalia o desenvolvimento da pragmática entre os 18 e os 47 meses. Métodos: Foram adotados todos os procedimentos recomendados pelas diretrizes internacionais sobre a adaptação de testes, culminando em estudo piloto com uma amostra de 120 inventários, respondidos pelos pais/cuidadores de crianças portuguesas da referida faixa etária. Resultados: Os coeficientes de consistência interna (Alfa de Cronbach) para a versão portuguesa do LUI situaram-se em 0,97 para a escala total e entre 0,71 e 0,96 para as subescalas. Conclusão: Os resultados preliminares dos estudos de adaptação e de validação do LUI-Pt para crianças portuguesas são promissores e asseguram a validade interna desta escala em termos da sua dimensionalidade e consistência interna

    Identification of features of electronic prescribing systems to support quality and safety in primary care using a modified Delphi process

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    <p>Abstract</p> <p>Background</p> <p>Electronic prescribing is increasingly being used in primary care and in hospitals. Studies on the effects of e-prescribing systems have found evidence for both benefit and harm. The aim of this study was to identify features of e-prescribing software systems that support patient safety and quality of care and that are useful to the clinician and the patient, with a focus on improving the quality use of medicines.</p> <p>Methods</p> <p>Software features were identified by a literature review, key informants and an expert group. A modified Delphi process was used with a 12-member multidisciplinary expert group to reach consensus on the expected impact of the features in four domains: patient safety, quality of care, usefulness to the clinician and usefulness to the patient. The setting was electronic prescribing in general practice in Australia.</p> <p>Results</p> <p>A list of 114 software features was developed. Most of the features relate to the recording and use of patient data, the medication selection process, prescribing decision support, monitoring drug therapy and clinical reports. The expert group rated 78 of the features (68%) as likely to have a high positive impact in at least one domain, 36 features (32%) as medium impact, and none as low or negative impact. Twenty seven features were rated as high positive impact across 3 or 4 domains including patient safety and quality of care. Ten features were considered "aspirational" because of a lack of agreed standards and/or suitable knowledge bases.</p> <p>Conclusions</p> <p>This study defines features of e-prescribing software systems that are expected to support safety and quality, especially in relation to prescribing and use of medicines in general practice. The features could be used to develop software standards, and could be adapted if necessary for use in other settings and countries.</p

    FDG-PET/CT imaging for staging and target volume delineation in conformal radiotherapy of anal carcinoma

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    Background: FDG-PET/CT imaging has an emerging role in staging and treatment planning of various tumor locations and a number of literature studies show that also the carcinoma of the anal canal may benefit from this diagnostic approach. We analyzed the potential impact of FDG-PET/CT in stage definition and target volume delineation of patients affected by carcinoma of the anal canal and candidates for curative radiotherapy. Methods: Twenty seven patients with biopsy proven anal carcinoma were enrolled. Pathology was squamous cell carcinoma in 20 cases, cloacogenic carcinoma in 3, adenocarcinoma in 2, and basal cell carcinoma in 2. Simulation was performed by PET/CT imaging with patient in treatment position. Gross Tumor Volume (GTV) and Clinical Target Volume (CTV) were drawn on CT and on PET/CT fused images. PET-GTV and PET-CTV were respectively compared to CT-GTV and CT-CTV by Wilcoxon rank test for paired data. Results: PET/CT fused images led to change the stage in 5/27 cases (18.5%): 3 cases from N0 to N2 and 2 from M0 to M1 leading to change the treatment intent from curative to palliative in a case. Based on PET/CT imaging, GTV and CTV contours changed in 15/27 (55.6%) and in 10/27 cases (37.0%) respectively. PET-GTV and PET-CTV resulted significantly smaller than CT-GTV (p = 1.2 7 10-4) and CT-CTV (p = 2.9 7 10-4). PET/CT-GTV and PET/CT-CTV, that were used for clinical purposes, were significantly greater than CT-GTV (p = 6 7 10-5) and CT-CTV (p = 6 7 10-5). Conclusions: FDG-PET/CT has a potential relevant impact in staging and target volume delineation of the carcinoma of the anal canal. Clinical stage variation occurred in 18.5% of cases with change of treatment intent in 3.7%. The GTV and the CTV changed in shape and in size based on PET/CT imaging

    Health care use and costs of adverse drug events emerging from outpatient treatment in Germany: A modelling approach

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    <p>Abstract</p> <p>Background</p> <p>This study's aim was to develop a first quantification of the frequency and costs of adverse drug events (ADEs) originating in ambulatory medical practice in Germany.</p> <p>Methods</p> <p>The frequencies and costs of ADEs were quantified for a base case, building on an existing cost-of-illness model for ADEs. The model originates from the U.S. health care system, its structure of treatment probabilities linked to ADEs was transferred to Germany. Sensitivity analyses based on values determined from a literature review were used to test the postulated results.</p> <p>Results</p> <p>For Germany, the base case postulated that about 2 million adults ingesting medications have will have an ADE in 2007. Health care costs related to ADEs in this base case totalled 816 million Euros, mean costs per case were 381 Euros. About 58% of costs resulted from hospitalisations, 11% from emergency department visits and 21% from long-term care. Base case estimates of frequency and costs of ADEs were lower than all estimates of the sensitivity analyses.</p> <p>Discussion</p> <p>The postulated frequency and costs of ADEs illustrate the possible size of the health problems and economic burden related to ADEs in Germany. The validity of the U.S. treatment structure used remains to be determined for Germany. The sensitivity analysis used assumptions from different studies and thus further quantified the information gap in Germany regarding ADEs.</p> <p>Conclusions</p> <p>This study found costs of ADEs in the ambulatory setting in Germany to be significant. Due to data scarcity, results are only a rough indication.</p

    First Neutrino Observations from the Sudbury Neutrino Observatory

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    The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed.Comment: Latex, 7 pages, 10 figures, Invited paper at Neutrino 2000 Conference, Sudbury, Canada, June 16-21, 2000 to be published in the Proceeding

    Understanding Uncertainties in Model-Based Predictions of Aedes aegypti Population Dynamics

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    Dengue is one of the most important insect-vectored human viral diseases. The principal vector is Aedes aegypti, a mosquito that lives in close association with humans. Currently, there is no effective vaccine available and the only means for limiting dengue outbreaks is vector control. To help design vector control strategies, spatial models of Ae. aegypti population dynamics have been developed. However, the usefulness of such models depends on the reliability of their predictions, which can be affected by different sources of uncertainty including uncertainty in the model parameter estimation, uncertainty in the model structure, measurement errors in the data fed into the model, individual variability, and stochasticity in the environment. This study quantifies uncertainties in the mosquito population dynamics predicted by Skeeter Buster, a spatial model of Ae. aegypti, for the city of Iquitos, Peru. The uncertainty quantification should enable us to better understand the reliability of model predictions, improve Skeeter Buster and other similar models by targeting those parameters with high uncertainty contributions for further empirical research, and thereby decrease uncertainty in model predictions
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