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991.
Hangjin Cho Setmg-A Lee Jooyong Kim 《东华大学学报(英文版)》2006,23(5):80-82
The far-infrared radiation (Far-IR) has good effects on us, promoting the circulation of the blood and metabolic. So textile products including far-IR have been developed. But it is very difficult to measure the amount of far-IR in the textile quicHy and correctly. Newly developed Mercury Cadmium Telluride (MCT) sensor system could solve this problem. 相似文献
992.
Optimal clustering for the web documents is known to complicated combinatorial Optimization problem and it is hard to develop a generally applicable oplimal algorithm. An accelerated simuIated arlneaIing aIgorithm is developed for automatic web document classification. The web document classification problem is addressed as the problem of best describing a match between a web query and a hypothesized web object. The normalized term frequency and inverse document frequency coetficient is used as a measure of the match. Test beds are generated on - line during the search by transforming model web sites. As a result,web sites can be clustered optimally in terms of keyword vectors of corresponding web documents. 相似文献
993.
The objective of this paper is to develop the maximum likelihood approach
for analyzing a finite mixture of structural equation models with missing data that are
missing at random. A Monte Carlo EM algorithm is proposed for obtaining the maximum
likelihood estimates. A well-known statistic in model comparison, namely the Bayesian
Information Criterion (BIC), is used for model comparison. With the presence of missing
data, the computation of the observed-data likelihood function value involved in the BIC
is not straightforward. A procedure based on path sampling is developed to compute this
function value. It is shown by means of simulation studies that ignoring the incomplete
data with missing entries gives less accurate ML estimates. An illustrative real example is
also presented. 相似文献
994.
We investigate the predictive performance of various classes of value‐at‐risk (VaR) models in several dimensions—unfiltered versus filtered VaR models, parametric versus nonparametric distributions, conventional versus extreme value distributions, and quantile regression versus inverting the conditional distribution function. By using the reality check test of White (2000), we compare the predictive power of alternative VaR models in terms of the empirical coverage probability and the predictive quantile loss for the stock markets of five Asian economies that suffered from the 1997–1998 financial crisis. The results based on these two criteria are largely compatible and indicate some empirical regularities of risk forecasts. The Riskmetrics model behaves reasonably well in tranquil periods, while some extreme value theory (EVT)‐based models do better in the crisis period. Filtering often appears to be useful for some models, particularly for the EVT models, though it could be harmful for some other models. The CaViaR quantile regression models of Engle and Manganelli (2004) have shown some success in predicting the VaR risk measure for various periods, generally more stable than those that invert a distribution function. Overall, the forecasting performance of the VaR models considered varies over the three periods before, during and after the crisis. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
995.
In an injection moulding process, the mould cooling s ystem is very important as an efficient and uniform cooling effect can improve b oth the productivity and part quality. Due to the complexity of the process, muc h research on the mould cooling analysis and cooling design optimization has bee n focused on the core and the cavity, excluding other systems of injection mould s. However, the runner system introduces a considerable amount of heat into the mould. In recent years, more and more hot runner sys... 相似文献
996.
Work-team has emerged as an important unit composi ng the organization today. The concepts relating to the properties of team-role t hat fit with today‘s business environment have attracted much attention from the theorists and researchers. A team having a balanced composition of team-ro les is called a balanced team. Theoretically, a balanced team usually renders a better team performance. Therefore, to improve the performance of the team, mana gement needs to ensure that their work teams are composed... 相似文献
997.
998.
大学生学生创业对于解决大学生就业难问题以及促进大学生群体进行科技创新和促进国家经济发展等方面都有积极的作用。然而相对于美国、日本等国家的大学生选择自主创业的高比率,我国大学生选择自主创业的数量却并不多。由麦可思研究院调查编著的《2014中国大学生就业报告》指出在2013届约727万人的大学毕业生中自主创业比例仅为2.3%,仅为2013年769770万就业人员的0.21‰。国内大学生自主创业不积极的深层原因是国内大学创业教育的不完善。针对此问题,该文将通过结合对国外大学生创业教育和国内创业教育现状进行研究,对上海大学生的创业心态进行问卷调查,总结并建立了相关的创业教育模型。 相似文献
999.
Lee JH Koh H Kim M Kim Y Lee SY Karess RE Lee SH Shong M Kim JM Kim J Chung J 《Nature》2007,447(7147):1017-1020
AMP-activated protein kinase (AMPK, also known as SNF1A) has been primarily studied as a metabolic regulator that is activated in response to energy deprivation. Although there is relatively ample information on the biochemical characteristics of AMPK, not enough data exist on the in vivo function of the kinase. Here, using the Drosophila model system, we generated the first animal model with no AMPK activity and discovered physiological functions of the kinase. Surprisingly, AMPK-null mutants were lethal with severe abnormalities in cell polarity and mitosis, similar to those of lkb1-null mutants. Constitutive activation of AMPK restored many of the phenotypes of lkb1-null mutants, suggesting that AMPK mediates the polarity- and mitosis-controlling functions of the LKB1 serine/threonine kinase. Interestingly, the regulatory site of non-muscle myosin regulatory light chain (MRLC; also known as MLC2) was directly phosphorylated by AMPK. Moreover, the phosphomimetic mutant of MRLC rescued the AMPK-null defects in cell polarity and mitosis, suggesting MRLC is a critical downstream target of AMPK. Furthermore, the activation of AMPK by energy deprivation was sufficient to cause dramatic changes in cell shape, inducing complete polarization and brush border formation in the human LS174T cell line, through the phosphorylation of MRLC. Taken together, our results demonstrate that AMPK has highly conserved roles across metazoan species not only in the control of metabolism, but also in the regulation of cellular structures. 相似文献
1000.
A firm understanding of the relationship between atmospheric carbon dioxide concentration and temperature is critical for interpreting past climate change and for predicting future climate change. A recent synthesis suggests that the increase in global-mean surface temperature in response to a doubling of the atmospheric carbon dioxide concentration, termed 'climate sensitivity', is between 1.5 and 6.2 degrees C (5-95 per cent likelihood range), but some evidence is inconsistent with this range. Moreover, most estimates of climate sensitivity are based on records of climate change over the past few decades to thousands of years, when carbon dioxide concentrations and global temperatures were similar to or lower than today, so such calculations tend to underestimate the magnitude of large climate-change events and may not be applicable to climate change under warmer conditions in the future. Here we estimate long-term equilibrium climate sensitivity by modelling carbon dioxide concentrations over the past 420 million years and comparing our calculations with a proxy record. Our estimates are broadly consistent with estimates based on short-term climate records, and indicate that a weak radiative forcing by carbon dioxide is highly unlikely on multi-million-year timescales. We conclude that a climate sensitivity greater than 1.5 degrees C has probably been a robust feature of the Earth's climate system over the past 420 million years, regardless of temporal scaling. 相似文献