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关键词： ERROR   ESTIMATION theory   SET theory   ANALYSIS of covariance   STANDARD deviations   DECOMPOSITION (Mathematics)  

摘要： Is it better to design a classifier and estimate its error on the full sample or to design a classifier on a training subset and estimate its error on the holdout test subset? Full-sample design provides the better classifier;nevertheless, one might choose holdout with the hope of better error estimation. A conservative criterion to decide the best course is to aimat a classifier whose error is less than a given bound. Then the choice between full-sample and holdout designs depends on which possesses the smaller expected bound. Using this criterion, we examine the choice between holdout and several full-sample error estimators using covariance models and a patient-data model. Full-sample design consistently outperforms holdout design. The relation between the two designs is revealed via a decomposition of the expected bound into the sum of the expected true error and the expected conditional standard deviation of the true error. Copyright (C) 2008 Marcel Brun et al.

关键词： Eutrophication   Harmful algal blooms (HABs)   Nitrogen   Nutrients   Phosphorus   Red tides  

摘要： Coastal waters of the United States (U.S.) are subject to many of the major harmful algal bloom (HAB) poisoning syndromes and impacts. These include paralytic shellfish poisoning (PSP), neurotoxic shellfish.;poisoning (NSP), amnesic shellfish poisoning (ASP), ciguatera fish poisoning (CFP) and various other HAB phenomena such as fish kills, loss of submerged vegetation, shellfish mortalities, and widespread marine mammal mortalities. Here, the occurrences of selected HABs in a selected set of regions are described in terms of their relationship to eutrophication, illustrating I a range of responses. Evidence suggestive of changes in the frequency, extent or magnitude of HABs in these areas is explored in the context of the nutrient sources underlying those blooms, both natural and anthropogenic. In some regions of the U.S., the linkages between HABs and eutrophication are clear and well documented, whereas in others, information is limited, thereby highlighting important areas for further research. (C) 2008 Elsevier B.V. All rights reserved.

关键词： psychotropic medicines   psycholeptics   psychoanaleptics   prevalence  

摘要： Little is known about psycholeptic and psychoanaleptic medicine (PM) use in the general population. This study presents prevalence data about PM use. The sample included 4310 individuals aged 20-79 from a general population health examination in a northern German area (participation proportion: 68.8%;Study of Health in Pomerania, SHIP). Medicines taken during the past seven days were assessed from the medicine packages or self-reports and classified according to the Anatomical Therapeutic Chemical (ATC) classification developed by the World Health Organization. In total, 6.3% of the sample reported PM intake, 8.7% of the women and 4.7% of the men. During the past 12 months prior to the health examination, 49.2% of the individuals with PM use consulted a general practitioner but not a neurologist or a psychiatrist. Among the study participants with PM use, 88.8% had one or more mental disorders during lifetime according to a screening questionnaire. It is concluded that considerable proportions of individuals with current PM use exist although lower than may be expected on the basis of the number of individuals with mental disorder in the general population. Copyright (C) 2008 John Wiley & Sons, Ltd.

关键词： GENE-EXPRESSION DATA   BREAST-CANCER   FOLLICULAR LYMPHOMA   SURVIVAL   PERFORMANCE   SIGNATURES   MARKER   RATIO   Data sampling   Large Numbers   Breast Cancer   Survival   signatures   Classifiers  

摘要： A major interest in gene expression microarray studies is to develop an accurate classifier which call be adopted in clinical practice. The Usage of large numbers of genes with small data samples may lead to overfitting in classification, and generate promising, but often nonreproducible results. Therefore, assessing the reproducibility of a classifier is necessary. Appropriate methods for validating a developed classifier and estimating its predicting accuracy are discussed. In addition, sonic mistakes that can arise in the cross Validation process are reviewed Using published articles in prominent medical journals, to prevent the indefinite results of a classifier development from leading to inappropriate treatment.

关键词： Graphene  

摘要： The effects of the interaction of few-layer graphene with electron donor and acceptor molecules have been investigated by employing Raman spectroscopy, and the results compared with those from electrochemical doping. The G-band softens progressively with increasing concentration of tetrathiafulvalene (TTF) which is an electron donor, while the band stiffens with increasing concentration of tetracyanoethylene (TCNE) which is an electron acceptor. Interaction with both TTF and TCNE broadens the G-band. Hole and electron doping by electrochemical means, however, stiffen and sharpen the G-band. The 2D-band position is also affected by interaction with TTF and TCNE. More importantly, the intensity of the 2D-band decreases markedly with the concentration of either. The ratio of intensities of the 2D-band and G-band decreases with an increase in TTF or TCNE concentration, and provides a means for carrier titration in the charge transfer system. Unlike the intensity of the 2D-band, that of the D-band increases on interaction with TTF or TCNE. All of these effects occur due to molecular charge transfer, also evidenced by the occurrence of charge transfer bands in the electronic absorption spectra. The electrical resistivity of graphene varies in opposite directions on interaction with TTF and TCNE, the resistivity depending on the concentration of either compound.

关键词： Esterases/chemistry   Esterases/genetics   Esterases/metabolism   Hydrogen Bonding   Macrolides/chemistry   Macrolides/chemistry   Macrolides/metabolism   Macrolides/metabolism   Molecular Structure   Multienzyme Complexes/chemistry   Multienzyme Complexes/genetics   Multienzyme Complexes/metabolism   Mutagenesis, Site-Directed   Polyketide Synthases/chemistry   Polyketide Synthases/genetics   Polyketide Synthases/metabolism   Protein Structure, Tertiary   Structure-Activity Relationship   Substrate Specificity  

摘要： The final step in polyketide synthase-mediated biosynthesis of macrocyclic polyketides is thioesterase (TE)-catalyzed cyclization of a linear polyketide acyl chain. TEs are highly specific in the chemistry they catalyze. Understanding the molecular basis for substrate specificity of TEs is crucial for engineering these enzymes to macrocyclize non-native linear substrates. We investigated the role of hydrogen bonding interactions in the substrate specificity of formation of an acyl-enzyme intermediate for the TE from the 6-deoxyerythronolide B biosynthetic pathway. Thirteen single site-directed mutants were constructed, via removal of side chain hydrogen bonding groups from the binding cavity. Specificity constants for four different substrates with and without hydrogen bond donors and acceptors were determined for the five active mutants. The relative magnitude of specificity constants for substrates did not change for the mutant TIES. Circular dichroism spectroscopy was used to show that the majority of the catalytically inactive mutants did not fold. Two mutations were identified that enabled mutant TEs to form a folded but catalytically inactive tertiary structure. Our data do not support a role for hydrogen bonding in mediating substrate specificity of bacterial polyketide synthase TEs. The highly conserved polar residues in the binding cavity appear to stabilize the unusual substrate channel, which passes through the enzyme. We propose that hydrophobic interactions between the binding cavity and substrate drive substrate specificity, as is seen in many protein-carbohydrate recognition events. This hypothesis is in agreement with high-resolution structural data for nonhydrolyzable acyl-enzyme intermediates from the picromycin TE.

关键词： 欧盟委员会   危险物质   包装   标签   法律  

摘要： 近日，为适应技术进步，欧盟委员会第31次修订了统一成员国关于危险物质分类、包装和标签的法律、法规和管理规定的理事会指令67／548／EEC。

关键词： 交通肇事案件   痕迹物证   物证检验   交通事故   事故现场   事故车辆   附着物  

摘要： 一、交通事故痕迹物证的概念及特点 交通事故痕迹物证是指交通事故现场或从交通事故现场带走能证明交通事故真实情况的物品、物质和痕迹，主要包括在事故车辆、人体、现场遗留的固定物、附着物、散落物或各种痕迹。

关键词： 改进的原因   原理和用具   实验过程  

摘要： 文中针对检验光合作用释放氧气实验原有实验设计的不足和诸多条件限制，往往导致失败的问题，提出了新的便于操作、简单易行的实验方案。

关键词： 实验室,医院   质量管理   医疗安全  

摘要： 随着卫生部《医疗机构临床实验窒管理办法》的实施以及医疗质量管理年活动的开展,临床实验室面临着严峻的考验。因为它涵盖了检验科管理的方方面面,特别是对实验室安全管理和质量管理方面提出了更高的要求,这也是为了搞好“以患者为中心,以提高医疗服务质量”为主题的医院管理年活动,其实质就足全面提高医院的医疗整体质量,保障人民群众生命健康与安全。另外,随着我国医疗制度改革的深入、医疗市场的激烈竞争以及患者自我保护意识的增强,越来越多的医疗纠纷接踵而来,检验结果成为临床医疗有力的证据,[第一段]