942 resultados para Under-the-curve
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Zoology v.2=pt.7-8 (1880-1881)
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Zoology v.21=pt.53 (1887) [Text]
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Zoology v.31=pt.64;78-79 (1888-1889)
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Zoology v.32=pt.80-82 (1888-1889)
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Zoology v.30=pt.51 (1888-1889) [Text]
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An appropriate assessment of end-to-end network performance presumes highly efficient time tracking and measurement with precise time control of the stopping and resuming of program operation. In this paper, a novel approach to solving the problems of highly efficient and precise time measurements on PC-platforms and on ARM-architectures is proposed. A new unified High Performance Timer and a corresponding software library offer a unified interface to the known time counters and automatically identify the fastest and most reliable time source, available in the user space of a computing system. The research is focused on developing an approach of unified time acquisition from the PC hardware and accordingly substituting the common way of getting the time value through Linux system calls. The presented approach provides a much faster means of obtaining the time values with a nanosecond precision than by using conventional means. Moreover, it is capable of handling the sequential time value, precise sleep functions and process resuming. This ability means the reduction of wasting computer resources during the execution of a sleeping process from 100% (busy-wait) to 1-1.5%, whereas the benefits of very accurate process resuming times on long waits are maintained.
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v.1 Text (1844)
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Zoology v.28 [pt.77]
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Aquest projecte es basa en l'estudi de l'oferiment de qualitat de servei en xarxes wireless i satel·litals. Per això l'estudi de les tècniques de cross-layer i del IEEE 802.11e ha sigut el punt clau per al desenvolupament teòric d’aquest estudi. Usant el simulador de xarxes network simulator, a la part de simulacions es plantegen tres situacions: l'estudi de la xarxa satel·lital, l'estudi del mètode d'accés HCCA i la interconnexió de la xarxa satel·lital amb la wireless. Encara que aquest últim punt, incomplet en aquest projecte, ha de ser la continuació per a futures investigacions.
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1. Model-based approaches have been used increasingly in conservation biology over recent years. Species presence data used for predictive species distribution modelling are abundant in natural history collections, whereas reliable absence data are sparse, most notably for vagrant species such as butterflies and snakes. As predictive methods such as generalized linear models (GLM) require absence data, various strategies have been proposed to select pseudo-absence data. However, only a few studies exist that compare different approaches to generating these pseudo-absence data. 2. Natural history collection data are usually available for long periods of time (decades or even centuries), thus allowing historical considerations. However, this historical dimension has rarely been assessed in studies of species distribution, although there is great potential for understanding current patterns, i.e. the past is the key to the present. 3. We used GLM to model the distributions of three 'target' butterfly species, Melitaea didyma, Coenonympha tullia and Maculinea teleius, in Switzerland. We developed and compared four strategies for defining pools of pseudo-absence data and applied them to natural history collection data from the last 10, 30 and 100 years. Pools included: (i) sites without target species records; (ii) sites where butterfly species other than the target species were present; (iii) sites without butterfly species but with habitat characteristics similar to those required by the target species; and (iv) a combination of the second and third strategies. Models were evaluated and compared by the total deviance explained, the maximized Kappa and the area under the curve (AUC). 4. Among the four strategies, model performance was best for strategy 3. Contrary to expectations, strategy 2 resulted in even lower model performance compared with models with pseudo-absence data simulated totally at random (strategy 1). 5. Independent of the strategy model, performance was enhanced when sites with historical species presence data were not considered as pseudo-absence data. Therefore, the combination of strategy 3 with species records from the last 100 years achieved the highest model performance. 6. Synthesis and applications. The protection of suitable habitat for species survival or reintroduction in rapidly changing landscapes is a high priority among conservationists. Model-based approaches offer planning authorities the possibility of delimiting priority areas for species detection or habitat protection. The performance of these models can be enhanced by fitting them with pseudo-absence data relying on large archives of natural history collection species presence data rather than using randomly sampled pseudo-absence data.
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This paper examines the performance of monetary policy under the new framework established in 1997 up to the end of the Labour government in May 2010. Performance was relatively good in the years before the crisis, but much weaker from 2008. The new framework largely neglected open economy issues, while the Treasury’s EMU assessment in 2003 can be interpreted in different ways. inflation targeting in the UK and elsewhere may have contributed in some way to the eruption and depth of the financial crisis from 2008, but UK monetary policy responded in a bold and innovative way. Overall, the design and operation of monetary policy were much better than in earlier periods, but there remains scope for significant further evolution.
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BACKGROUND AND OBJECTIVES: Cytochrome P450 (CYP) 3A4 is the main CYP isozyme involved in methadone metabolism. We investigated the influence of grapefruit juice, which contains inhibitors of intestinal CYP3A, on the steady-state pharmacokinetics of methadone. METHODS: For 5 days, 8 patients undergoing methadone maintenance treatment received 200 mL water or grapefruit juice 30 minutes before and again together with their daily dose of methadone. Blood sampling for R-, S-, and R,S-methadone plasma determination was performed over a 24-hour period. CYP3A activity was determined by measuring the plasma 1'-hydroxymidazolam/midazolam ratio. RESULTS: A decrease in the midazolam ratio was measured in all patients after grapefruit juice (mean +/- SD before grapefruit juice, 9.3 +/- 5.9; mean +/- SD after grapefruit juice, 3.9 +/- 1.2; P <.05). Grapefruit juice led to a mean 17% increase in the area under the curve extrapolated to 24 hours for both enantiomers of methadone (range, 3% to 29% [P <.005]; range, -4% to 37% [P <.05]; and range, 1% to 32% [P <.01]; for R-, S-, and R,S-methadone, respectively). A similar increase in peak level and decrease in apparent clearance were measured with grapefruit juice, whereas time to peak level, terminal half-life, and apparent volume during the terminal phase of R-, S-, and R,S-methadone were not affected by grapefruit juice. No symptom of overmedication was either detected by the clinical staff or reported by the patients. CONCLUSIONS: Grapefruit juice administration is associated with a modest increase in methadone bioavailability, which is not expected to endanger patients. However, it cannot be excluded that a much stronger effect may occur in some patients, and thus grapefruit juice intake is not recommended during methadone maintenance treatment, in particular in patients initiating such a treatment.
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Guidance on the transfer of mentally disordered patients detained under the Mental Health (NI) Order 1986 to and from Hospitals in Great Britain - August 2011.
Credit risk contributions under the Vasicek one-factor model: a fast wavelet expansion approximation
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To measure the contribution of individual transactions inside the total risk of a credit portfolio is a major issue in financial institutions. VaR Contributions (VaRC) and Expected Shortfall Contributions (ESC) have become two popular ways of quantifying the risks. However, the usual Monte Carlo (MC) approach is known to be a very time consuming method for computing these risk contributions. In this paper we consider the Wavelet Approximation (WA) method for Value at Risk (VaR) computation presented in [Mas10] in order to calculate the Expected Shortfall (ES) and the risk contributions under the Vasicek one-factor model framework. We decompose the VaR and the ES as a sum of sensitivities representing the marginal impact on the total portfolio risk. Moreover, we present technical improvements in the Wavelet Approximation (WA) that considerably reduce the computational effort in the approximation while, at the same time, the accuracy increases.