680 resultados para 889
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The results of three wave mixing experiments in photorefractive Bi12SiO20 are presented. The results confirm theoretical predictions that amplification by three wave mixing is strongly dependent on the phase relationship between the three beams at the input to the medium.
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Objective: To independently evaluate the impact of the second phase of the Health Foundation's Safer Patients Initiative (SPI2) on a range of patient safety measures. Design: A controlled before and after design. Five substudies: survey of staff attitudes; review of case notes from high risk (respiratory) patients in medical wards; review of case notes from surgical patients; indirect evaluation of hand hygiene by measuring hospital use of handwashing materials; measurement of outcomes (adverse events, mortality among high risk patients admitted to medical wards, patients' satisfaction, mortality in intensive care, rates of hospital acquired infection). Setting: NHS hospitals in England. Participants: Nine hospitals participating in SPI2 and nine matched control hospitals. Intervention The SPI2 intervention was similar to the SPI1, with somewhat modified goals, a slightly longer intervention period, and a smaller budget per hospital. Results: One of the scores (organisational climate) showed a significant (P=0.009) difference in rate of change over time, which favoured the control hospitals, though the difference was only 0.07 points on a five point scale. Results of the explicit case note reviews of high risk medical patients showed that certain practices improved over time in both control and SPI2 hospitals (and none deteriorated), but there were no significant differences between control and SPI2 hospitals. Monitoring of vital signs improved across control and SPI2 sites. This temporal effect was significant for monitoring the respiratory rate at both the six hour (adjusted odds ratio 2.1, 99% confidence interval 1.0 to 4.3; P=0.010) and 12 hour (2.4, 1.1 to 5.0; P=0.002) periods after admission. There was no significant effect of SPI for any of the measures of vital signs. Use of a recommended system for scoring the severity of pneumonia improved from 1.9% (1/52) to 21.4% (12/56) of control and from 2.0% (1/50) to 41.7% (25/60) of SPI2 patients. This temporal change was significant (7.3, 1.4 to 37.7; P=0.002), but the difference in difference was not significant (2.1, 0.4 to 11.1; P=0.236). There were no notable or significant changes in the pattern of prescribing errors, either over time or between control and SPI2 hospitals. Two items of medical history taking (exercise tolerance and occupation) showed significant improvement over time, across both control and SPI2 hospitals, but no additional SPI2 effect. The holistic review showed no significant changes in error rates either over time or between control and SPI2 hospitals. The explicit case note review of perioperative care showed that adherence rates for two of the four perioperative standards targeted by SPI2 were already good at baseline, exceeding 94% for antibiotic prophylaxis and 98% for deep vein thrombosis prophylaxis. Intraoperative monitoring of temperature improved over time in both groups, but this was not significant (1.8, 0.4 to 7.6; P=0.279), and there were no additional effects of SPI2. A dramatic rise in consumption of soap and alcohol hand rub was similar in control and SPI2 hospitals (P=0.760 and P=0.889, respectively), as was the corresponding decrease in rates of Clostridium difficile and meticillin resistant Staphylococcus aureus infection (P=0.652 and P=0.693, respectively). Mortality rates of medical patients included in the case note reviews in control hospitals increased from 17.3% (42/243) to 21.4% (24/112), while in SPI2 hospitals they fell from 10.3% (24/233) to 6.1% (7/114) (P=0.043). Fewer than 8% of deaths were classed as avoidable; changes in proportions could not explain the divergence of overall death rates between control and SPI2 hospitals. There was no significant difference in the rate of change in mortality in intensive care. Patients' satisfaction improved in both control and SPI2 hospitals on all dimensions, but again there were no significant changes between the two groups of hospitals. Conclusions: Many aspects of care are already good or improving across the NHS in England, suggesting considerable improvements in quality across the board. These improvements are probably due to contemporaneous policy activities relating to patient safety, including those with features similar to the SPI, and the emergence of professional consensus on some clinical processes. This phenomenon might have attenuated the incremental effect of the SPI, making it difficult to detect. Alternatively, the full impact of the SPI might be observable only in the longer term. The conclusion of this study could have been different if concurrent controls had not been used.
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Limited energy is a big challenge for large scale wireless sensor networks (WSN). Previous research works show that modulation scaling is an efficient technique to reduce energy consumption. However, the impacts of using modulation scaling on packet delivery latency and loss are not considered, which may have adverse effects on the application qualities. In this paper, we study this problem and propose control schemes to minimize energy consumption while ensuring application qualities. We first analyze the relationships of modulation scaling and energy consumption, end-to-end delivery latency and packet loss ratio. With the analytical model, we develop a centralized control scheme to adaptively adjust the modulation levels, in order to minimize energy consumption and ensure the application qualities. To improve the scalability of the centralized control scheme, we also propose a distributed control scheme. In this scheme, the sink will send the differences between the required and measured application qualities to the sensors. The sensors will update their modulation levels with the local information and feedback from the sink. Experimental results show the effectiveness of energy saving and QoS guarantee of the control schemes. The control schemes can adapt efficiently to the time-varying requirements on application qualities. Copyright © 2005 The Institute of Electronics, Information and Communication Engineers.
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There are a great deal of approaches in artificial intelligence, some of them also coming from biology and neirophysiology. In this paper we are making a review, discussing many of them, and arranging our discussion around the autonomous agent research. We highlight three aspect in our classification: type of abstraction applied for representing agent knowledge, the implementation of hypothesis processing mechanism, allowed degree of freedom in behaviour and self-organizing. Using this classification many approaches in artificial intelligence are evaluated. Then we summarize all discussed ideas and propose a series of general principles for building an autonomous adaptive agent.
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Higher and further education institutions are increasingly using social software tools to support teaching and learning. A growing body of research investigates the diversity of tools and their range of contributions. However, little research has focused on investigating the role of the educator in the context of a social software initiative, even though the educator is critical for the introduction and successful use of social software in a course environment. Hence, we argue that research on social software should place greater emphasis on the educators, as their roles and activities (such as selecting the tools, developing the tasks and facilitating the student interactions on these tools) are instrumental to most aspects of a social software initiative. To this end, we have developed an agenda for future research on the role of the educator. Drawing on role theory, both as the basis for a systematic conceptualization of the educator role and as a guiding framework, we have developed a series of concrete research questions that address core issues associated with the educator roles in a social software context and provide recommendations for further investigations. By developing a research agenda we hope to stimulate research that creates a better understanding of the educator’s situation and develops guidelines to help educators carry out their social software initiatives. Considering the significant role an educator plays in the initiation and conduct of a social software initiative, our research agenda ultimately seeks to contribute to the adoption and efficient use of social software in the educational domain.
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A piaci kudarcok számos formája ismert a közgazdászok számára, ezek közül a környezetvédelem területén a külső gazdasági hatásokkal (az externáliákkal) kapcsolatosak a legismertebbek. A piaci kudarcok miatt a gazdaság nincs Pareto-optimális helyzetben, azaz egyesek jóléte nem növelhető úgy, hogy eközben mások jóléte ne csökkenjen. Kérdés, hogy ez egy-egy környezetszennyező vállalat vagy iparág esetén azt jelenti-e, hogy a piaci mechanizmust teljesen ki kell iktatnunk a probléma orvoslásakor, vagy azért bizonyos szerepet a piac továbbra is betölthet a nehézség leküzdésében. /===/ Economists are familiar with many forms of market failure, among the best known being the economic externalities in the field of environmental protection. Due to the market failures, the economy is not in a Pareto-optimal situation, in other words, the welfare of some cannot be raised without reducing the welfare of others. The question is whether this means in the case of a polluting firm or industry that the market mechanism has to be excluded when remedying the problem, or whether the market can still play some part in overcoming the difficulties.
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Contents: I. Entrepreneurial inclination during state socialism: - On entrepreneurial inclination; - Crisis, expectations, entrepreneurial inclination; - Where do entrepreneurs come from? On the third way, the second economy, and entrepreneurial inclination; ____ II. Entrepreneurial spirit and post-socialist transformation: - The upswing of entrepreneurial inclination between 1988 and 1990; - Entrepreneurship and perception of economic changes in the early 1990s; _____ III. Long-term changes and a European comparative perspective: - From crisis to crisis: long-term change of entrepreneurial inclination; - The effect of entrepreneurial inclination upon entrepreneurial career and well-being; - Entrepreneurial inclination in comparative perspective.
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OBJECTIVE: The orexigenic gut hormone ghrelin and its receptor are present in pancreatic islets. Although ghrelin reduces insulin secretion in rodents, its effect on insulin secretion in humans has not been established. The goal of this study was to test the hypothesis that circulating ghrelin suppresses glucose-stimulated insulin secretion in healthy subjects. RESEARCH DESIGN AND METHODS: Ghrelin (0.3, 0.9 and 1.5 nmol/kg/h) or saline was infused for more than 65 min in 12 healthy patients (8 male/4 female) on 4 separate occasions in a counterbalanced fashion. An intravenous glucose tolerance test was performed during steady state plasma ghrelin levels. The acute insulin response to intravenous glucose (AIRg) was calculated from plasma insulin concentrations between 2 and 10 min after the glucose bolus. Intravenous glucose tolerance was measured as the glucose disappearance constant (Kg) from 10 to 30 min. RESULTS: The three ghrelin infusions raised plasma total ghrelin concentrations to 4-, 15-, and 23-fold above the fasting level, respectively. Ghrelin infusion did not alter fasting plasma insulin or glucose, but compared with saline, the 0.3, 0.9, and 1.5 nmol/kg/h doses decreased AIRg (2,152 +/- 448 vs. 1,478 +/- 2,889, 1,419 +/- 275, and 1,120 +/- 174 pmol/l) and Kg (0.3 and 1.5 nmol/kg/h doses only) significantly (P < 0.05 for all). Ghrelin infusion raised plasma growth hormone and serum cortisol concentrations significantly (P < 0.001 for both), but had no effect on glucagon, epinephrine, or norepinephrine levels (P = 0.44, 0.74, and 0.48, respectively). CONCLUSIONS: This is a robust proof-of-concept study showing that exogenous ghrelin reduces glucose-stimulated insulin secretion and glucose disappearance in healthy humans. Our findings raise the possibility that endogenous ghrelin has a role in physiologic insulin secretion, and that ghrelin antagonists could improve beta-cell function.
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The polar compound (NSO) fractions of seabed petroleums and sediment extracts from the Guaymas Basin hydrothermal system have been analyzed by gas chromatography and gas chromatography-mass spectrometry. The oils were collected from the interiors and exteriors of high temperature hydrothermal vents and represent hydrothermal pyrolysates that have migrated to the seafloor by hydrothermal fluid circulation. The downcore samples are representative of both thermally unaltered and thermally altered sediments. The survey has revealed the presence of oxygenated compounds correlated with samples exhibiting a high degree of thermal maturity. Several homologous series of related ketone isomers are enriched in the interiors of the hydrothermal vent samples or in hydrothermally-altered sequences of the downcore sediments (DSDP Holes 477 and 481A). The n-alkanones range in carbon number from C11 to C33 with a Cmax from 14 to 23, distributions that are similar to those of the n-alkanes. The alkan-2-ones are usually in highest concentrations, with lower amounts of 3-, 4-, 5-, 6-, 7- (and higher) alkanones, and they exhibit no carbon number preference (there is an odd carbon number preference of alkanones observed for downcore samples). The alkanones are enriched in the interiors of the hydrothermal vent spires or in downcore hydrothermally-altered sediments, indicating an origin at depth or in the hydrothermal fluids and not from an external biogenic deposition. Minor amounts of C13 and C18 isoprenoid ketones are also present. Simulation of the natural hydrothermal alternation process by laboratory hydrous pyrolysis techniques provided information regarding the mode of alkanone formation. Hydrous pyrolysis of n-C32H66 at 350°C for 72 h with water only or water with inorganic additives has been studied using a stainless steel reaction vessel. In each experiment oxygenated hydrocarbons, including alkanones, were formed from the n-alkane. The product distributions indicate a reaction pathway consisting of n-alkanes and a-olefins as primary cracking products with internal olefins and alkanones as secondary reaction products. Hydrous pyrolyses of Messel shale spiked with molecular probes have been performed under similar time and temperature constraints to produce alkanone distributions like those found in the hydrothermal vent petroleums.
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In this article, as part of the Erasmus+ project “Divercity”, we focus on the collection and analysis of good practices in Spain and other countries in Europe. The project revolves around the development of methods that valorize cultural diversity and in this respect, identifying and sharing best practices on diversity and inclusion through artistic mediation inside museums, culture institutions, our urban walks, forms an mandatory stage of the research process.
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A gestão do conhecimento (GC) é uma das recentes abordagens da administração contemporânea, cujo foco engloba o conceito de conhecimento como recurso estratégico, sendo que suas técnicas, práticas e iniciativas gerenciais encontram-se em momento de consolidação. Muitos estudos acadêmicos sobre gestão do conhecimento estão sendo realizados no campo da Administração, com o objetivo de sistematizar os conceitos, as práticas e as contribuições para o poder de competição das empresas (NONAKA e TAKEUCHI, 1997; EISENHARDT e SANTOS, 2000; PROBST, RAUB e ROMHARDT, 2002; DALKIR, 2005). Esta pesquisa objetivou classificar as empresas do setor elétricoeletrônico brasileiro de acordo com o estágio de institucionalização da gestão do conhecimento, bem como verificar as contribuições das práticas de GC para seu poder competitivo. Foi realizado um survey a partir da listagem de 553 empresas elétricas e eletrônicas atuantes no Brasil e participantes da Associação Brasileira da Indústria Elétrica e Eletrônica (ABINEE), tendo sido averiguada uma amostra formada por 56 empresas respondentes. Os principais resultados encontrados foram: a) as empresas pesquisadas estão nos estágios iniciais de institucionalização de GC e b) as contribuições para o poder de competição, realizadas com adoção das práticas de GC, tinham como objetivo fortalecer a cultura de compartilhamento e disseminação do conhecimento, bem como, criar o ambiente favorável para o trabalho em equipe.