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Selection Criterion (selection + criterion)
Selected AbstractsFast display of large-scale forest with fidelityCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 2 2006Huaisheng Zhang Abstract We propose a new hierarchical representation for a forest model, namely hierarchical layered depth mosaics (HLDM). Each node in the HLDM comprises a number of discrete textured quadrilaterals, called depth mosaics (DMs). The DMs are generated from the sampled depth images of the polygonal tree models. Meanwhile, their textures are compressed by a new approach accounting for occlusion. Our rendering procedure traverses the HLDM and renders the appropriate nodes according to a view-dependent selection criterion. A blending scheme is adopted to mitigate the visual ,popping' caused by the transition of levels of detail. The experiment demonstrates that the viewer could interactively walk or fly above the forest with fidelity. Copyright © 2006 John Wiley & Sons, Ltd. [source] Environmental supply chain management, ISO 14001 and RoHS.CORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 6 2008How are small companies in the electronics sector managing? Abstract This study explores the use of environmental management systems for initiating and controlling environmental improvements in the context of supply chain cooperation. It examines how environmental requirements are reaching smaller companies in the electronics supply chain, especially in the light of recent legal changes such as enforcement of the RoHS Directive. It is based on qualitative interviews with environmental and purchasing managers of 21 small and medium-sized companies. The results point out a lack of significant drivers for these companies to implement proactive measures when dealing with environmental issues, owing to limited customer pressure. RoHS and legal compliance are the only environmental customer criteria to be met, while ISO 14001 works as an optional supplier selection criterion. In consequence, companies are not focusing on environmental work within their supply chains, and the potential of influencing the environmental profile of suppliers by shaping their ISO 14001 is not used. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment. [source] Reach-scale channel geometry of a mountain riverEARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2004Ellen Wohl Abstract Mountain rivers can be subject to strong constraints imposed by changes in gradient and grain size supplied by processes such as glaciation and rockfall. Nonetheless, adjustments in the channel geometry and hydraulics of mountain rivers at the reach scale can produce discernible patterns analogous to those in fully alluvial rivers. Mountain rivers can differ in that imposed reach-scale gradient is an especially important control on reach-scale channel characteristics, as indicated by examination of North St Vrain Creek in Colorado. North St Vrain Creek drains 250 km2 of the Rocky Mountains. We used 25 study reaches within the basin to examine controls on reach-scale channel geometry. Variables measured included channel geometry, large woody debris, grain size, and mean velocity. Drainage area at the study reaches ranged from 2·2 to 245 km2, and gradient from 0·013 to 0·147 m m,1. We examined correlations among (1) potential reach-scale response variables describing channel bankfull dimension and shape, hydraulics, bedform wavelength and amplitude, grain size, ,ow resistance, standard deviation of hydraulic radius, and volume of large woody debris, and (2) potential control variables that change progressively downstream (drainage area, discharge) or that are likely to re,ect a reach-speci,c control (bed gradient). We tested the hypothesis that response variables correlate most strongly with local bed gradient because of the segmented nature of mountain channels. Results from simple linear regression analyses indicate that most response variables correlate best with gradient, although channel width and width/depth ratio correlate best with discharge. Multiple regression analyses using Mallow's Cp selection criterion and log-transformation of all variables produced similar results in that most response variables correlate strongly with gradient. These results suggest that the hypothesis is partially supported: channel bed gradient is likely to be a good predictor for many reach-scale response variables along mountain rivers, but discharge is also an important predictor for some response variables. Copyright © 2004 John Wiley & Sons, Ltd. [source] Is Teaching Experience Necessary for Reliable Scoring of Extended English Questions?EDUCATIONAL MEASUREMENT: ISSUES AND PRACTICE, Issue 2 2009Lucy Royal-Dawson Hundreds of thousands of raters are recruited internationally to score examinations, but little research has been conducted on the selection criteria for these raters. Many countries insist upon teaching experience as a selection criterion and this has frequently become embedded in the cultural expectations surrounding the tests. Shortages in raters for some of England's national examinations has led to non-teachers being hired to score a small minority of items and changes in technology have fostered this approach. For a National Curriculum test in English taken at age 14, this study investigated whether teaching experience was a necessary selection criterion for all aspects of the examination. Fifty-seven raters with different backgrounds were trained in the normal manner and scored the same 97 students' work. Accuracy was investigated using a cross-classified multilevel model of absolute score differences with accuracy measures at level 1 and raters crossed with candidates at level 2. By comparing the scoring accuracy of graduates with a degree in English, teacher trainees, experienced teachers and experienced raters, this study found that teaching experience was not a necessary selection criterion. A rudimentary model for allocation of raters to different question types is proposed and further research to investigate the limits of necessary qualifications for scoring is suggested. [source] Adaptive preconditioning of linear stochastic algebraic systems of equationsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 11 2007Y. T. Feng Abstract This paper proposes an adaptively preconditioned iterative method for the solution of large-scale linear stochastic algebraic systems of equations with one random variable that arise from the stochastic finite element modelling of linear elastic problems. Firstly, a Rank-one posteriori preconditioner is introduced for a general linear system of equations. This concept is then developed into an effective adaptive preconditioning scheme for the iterative solution of the stochastic equations in the context of a modified Monte Carlo simulation approach. To limit the maximum number of base vectors used in the scheme, a simple selection criterion is proposed to update the base vectors. Finally, numerical experiments are conducted to assess the performance of the proposed adaptive preconditioning strategy, which indicates that the scheme with very few base vectors can improve the convergence of the standard Incomplete Cholesky preconditioning up to 50%. Copyright © 2006 John Wiley & Sons, Ltd. [source] Enzymes involved in flavour formation by bacteria isolated from the smear population of surface-ripened cheeseINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2004A G Williams Twenty-five bacterial isolates recovered from the surface population of smear-ripened cheese were assigned phenotypically as Brevibacterium spp., Corynebacterium spp. and Aureobacterium spp. using the Biolog GP2 microplate system and database. The range and activity of hydrolytic enzymes involved in the formation of cheese flavour constituents were monitored in cell-free lysates of the isolates. Esterase activity and the presence of a range of enzymes involved in amino acid release and breakdown was confirmed in all strains examined although there were pronounced interspecies and strain differences in the level of activity detected. Peptidolytic activities present in the smear bacteria included dipeptidyl peptidase and aminopeptidases that cleaved various N-terminal amino acids including proline. Subsequent breakdown of the released aromatic and branched-chain amino acids was mediated by ,-keto acid dependent aminotransferase action and several of the isolates were able to form thiols from sulphur-containing amino acid precursors. It was confirmed that the enzymic activity of the smear population could be manipulated by the use of defined starter cultures comprising selected combinations of smear isolates. The hydrolytic activities of the smear bacteria are involved in the generation of cheese flavour compounds and the enzyme profile is thus an important selection criterion for strains to be evaluated for use in defined surface smear preparations. [source] The persistence in hedge fund performance: extended analysisINTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 3 2009Daniel P. J. Capocci Abstract This study analyses and decomposes hedge fund returns to detect a systematic hedge fund selection criterion that enables investors to consistently and significantly outperform classical equities and bond indices over a full market cycle and over bullish and bearish market periods. The methodology used is adapted from Capocci and Hübner. The measures used include the returns, the volatility, the Sharpe score, the alpha, the beta, the skewness and the kurtosis. Measures incorporating the volatility display very strong ability to assist investors in creating alpha and consistently and significantly outperform classical indices. A sub-period analysis is performed to check the robustness of the results. Copyright © 2008 John Wiley & Sons, Ltd. [source] Relationship between Carbon Isotope Discrimination, Mineral Content and Gas Exchange Parameters in Vegetative Organs of Wheat Grown under Three Different Water RegimesJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 3 2010L. Zhu Abstract Carbon isotope discrimination (,) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of high cost for , analysis, attempts have been made to identify alternative screening criteria. Ash content (ma) has been proposed as an alternative criterion for , in wheat and barley. A pot experiment was conducted to analyse the relationship between ,, mineral content and gas exchange parameters in seedlings and leaves of bread wheat (Triticum aestivum L.). Plants of 10 genotypes were cultivated under three different water regimes corresponding to moderate (T3), intermediate (T2) and severe drought (T1) stress obtained by maintaining soil humidity at 75 %, 55 % and 45 % of the humidity at field capacity respectively. , and ma in seedlings and leaves showed significant differences among the three water treatments. Significant positive correlations were found between , and ma in seedlings and leaves at elongation and anthesis stages in severe drought stress (T1). , was negatively associated with potassium (K) content in intermediate drought stress (T2) and positively with magnesium (Mg) content in T2 and T3 (moderate drought stress) in flag leaf at anthesis. There were negative correlations between , and single-leaf intrinsic water-use efficiency (WT) in T2 and T3 at anthesis stage. Stronger positive associations were noted between , and stomatal conductance (gs) in T1 and T2 than in T3 at anthesis. These results suggested that , is a good trait as an indirect selection criterion for genotypic improvement in transpiration efficiency, while ma is a possible alternative criterion of , in wheat vegetative organs, especially in stressed environments. Significant association was found between , and K, Mg and Ca contents that would merit being better investigated. [source] Relationship between Carbon Isotope Discrimination and Mineral Content in Wheat Grown under Three Different Water RegimesJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2008L. Zhu Abstract Carbon isotope discrimination (,) has been proposed as an indirect selection criterion for transpiration efficiency and grain yield in wheat. However, because of the high cost for , analysis, attempts have been carried out to identify alternative screening criteria. Ash content (ma) has been proposed as an alternative criterion for , in wheat and barley. A pot experiment was conducted to analyse the relationship between , and ma in flag leaf and grain. Plants of 10 genotypes were cultivated under three different water regimes corresponding to moderate, intermediate and severe drought stress obtained by maintaining soil humidity at 75 %, 55 % and 45 % of the humidity at field capacity, respectively. , and ma in flag leaf and grain showed significant differences between the moderate, intermediate and severe drought stress levels. Significant correlations were found among genotypes for , and ma in flag leaf under severe drought stress, and for , and ma in grain under intermediate and moderate drought stress. In flag leaf at anthesis, , was negatively associated to K content and positively to Mg content. At maturity, , in grain was negatively correlated with Mg and Ca contents in flag leaf and grain, respectively. These results suggested that these traits may be potentially useful traits, which could be surrogates for ,. [source] Relationship of Carbon Isotope Discrimination to Water Use Efficiency and Productivity of Barley Under Field and Greenhouse ConditionsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2007A. O. Anyia Abstract This study was conducted to evaluate the application of carbon isotope discrimination (CID) as a selection criterion for improving water use efficiency (WUE) and productivity of barley (Hordeum vulgare L.) under field and drought-stress conditions in a greenhouse. A total of 54 genotypes were screened for variability in CID under field conditions, while 23 genotypes were evaluated under water-deficit conditions in the greenhouse. A survey of leaf CID of 54 genotypes at two field locations showed more than 2.14, difference between extreme genotypes. Significant (P , 0.05) genotypic variation was found in WUE and CID that had a negative strong correlation. There was a negative correlation between leaf CID and aerial biomass in the greenhouse and among six-row genotypes in the field. Correlations between leaf CID across field locations and across irrigation regimes in the greenhouse were significant (experiment 1, r = 0.79 and 0.94 for six- and two-row genotypes), suggesting stability of the CID trait across different environments. Overall, these results indicate the potential of leaf CID as a reliable method for selecting for high WUE and productivity in barley breeding programmes in the Canadian prairies. Further work is currently underway to determine heritability/genetics of leaf CID and application of molecular marker-assisted selection for the traits in barley breeding programmes. [source] Effects of Practical Constraints on Item Selection Rules at the Early Stages of Computerized Adaptive TestingJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 2 2004Shu-Ying Chen The purpose of this study was to compare the effects of four item selection rules,(1) Fisher information (F), (2) Fisher information with a posterior distribution (FP), (3) Kullback-Leibler information with a posterior distribution (KP), and (4) completely randomized item selection (RN),with respect to the precision of trait estimation and the extent of item usage at the early stages of computerized adaptive testing. The comparison of the four item selection rules was carried out under three conditions: (1) using only the item information function as the item selection criterion; (2) using both the item information function and content balancing; and (3) using the item information function, content balancing, and item exposure control. When test length was less than 10 items, FP and KP tended to outperform F at extreme trait levels in Condition 1. However, in more realistic settings, it could not be concluded that FP and KP outperformed F, especially when item exposure control was imposed. When test length was greater than 10 items, the three nonrandom item selection procedures performed similarly no matter what the condition was, while F had slightly higher item usage. [source] Relationship between Carbon Isotope Discrimination and Grain Yield in Spring Wheat Cultivated under Different Water RegimesJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 10 2007Xing Xu Abstract In C3 plants, carbon isotope discrimination (,) has been proposed as an indirect selection criterion for grain yield. Reported correlations between , and grain yield however, differ highly according to the analyzed organ or tissue, the stage of sampling, and the environment and water regime. In a first experiment carried out in spring wheat during two consecutive seasons in the dry conditions of northwest Mexico (Ciudad Obregon, Sonora), different water treatments were applied, corresponding to the main water regimes available to spring wheat worldwide, and the relationships between , values of different organs and grain yield were examined. Under terminal (post-anthesis) water stress, grain yield was positively associated with , in grain at maturity and in leaf at anthesis, confirming results previously obtained under Mediterranean environments. Under early (pre-anthesis) water stress and residual moisture stress, the association between grain , and yield was weaker and highly depended on the quantity of water stored in the soil at sowing. No correlation was found between , and grain yield under optimal irrigation. The relationship between , and grain yield was also studied during two consecutive seasons in 20 bread wheat cultivars in the Ningxia region (Northern China), characterized by winter drought (pre-anthesis water stress). Wheat was grown under rainfed conditions in two locations (Guyuan and Pengyang) and under irrigated conditions in another two (Yinchuan and Huinong). In Huinong, the crop was also exposed to salt stress. Highly significant positive associations were found between leaf and grain , and grain yields across the environments. The relationship between , and yield within environments highly depended on the quantity of water stored in the soil at sowing, the quantity and distribution of rainfall during the growth cycle, the presence of salt in the soil, and the occurrence of irrigation before anthesis. These two experiments confirmed the value of , as an indirect selection criterion for yield and a phenotyping tool under post-anthesis water stress (including limited irrigation). [source] A Metric of Maternal Prenatal Risk Drinking Predicts Neurobehavioral Outcomes in Preschool ChildrenALCOHOLISM, Issue 4 2009Lisa M. Chiodo Background:, Fetal Alcohol Spectrum Disorders (FASDs), including Fetal Alcohol Syndrome, continue to be high-incidence developmental disorders. Detection of patterns of maternal drinking that place fetuses at risk for these disorders is critical to diagnosis, treatment, and prevention, but is challenging and often insufficient during pregnancy. Various screens and measures have been used to identify maternal risk drinking but their ability to predict child outcome has been inconsistent. This study hypothesized that a metric of fetal "at-risk" alcohol exposure (ARAE) derived from several indicators of maternal self-reported drinking would predict alcohol-related neurobehavioral dysfunctions in children better than individual measures of maternal alcohol consumption alone. Methods:, Self-reported peri-conceptional and repeated maternal drinking during pregnancy were assessed with semi-structured interviews and standard screens, i.e., the CAGE, T-ACE, and MAST, in a prospective sample of 75 African-American mothers. Drinking volumes per beverage type were converted to standard quantity and frequency measures. From these individual measures and screening instruments, a simple dichotomous index of prenatal ARAE was defined and used to predict neurobehavioral outcomes in the 4- to 5-year-old offspring of these women. Study outcomes included IQ, attention, memory, visual-motor integration, fine motor skill, and behavior. Statistical analyses controlled for demographic and other potential confounders. Results:, The current "at-risk" drinking metric identified over 62% of the mothers as drinking at risk levels,23% more than the selection criterion identified,and outperformed all individual quantity and frequency consumption measures, including averages of weekly alcohol use and "binge" alcohol exposures (assessed as intake per drinking occasion), as well as an estimate of the Maternal Substance Abuse Checklist (Coles et al., 2000), in predicting prenatal alcohol-related cognitive and behavioral dysfunction in 4- to 5-year-old children. Conclusions:, A metric reflecting multiple indices of "at-risk" maternal alcohol drinking in pregnancy had greater utility in predicting various prenatal alcohol-related neurobehavioral dysfunction and deficits in children compared to individual measures of maternal self-reported alcohol consumption or a previous maternal substance abuse index. Assessing fetal risk drinking in pregnant women was improved by including multiple indicators of both alcohol consumption and alcohol-related consequences and, if appropriate practical applications are devised, may facilitate intervention by health care workers during pregnancy and potentially reduce the incidence or severity of FASDs. [source] Can Simple Doppler Measurements Estimate Interatrial Conduction Time?PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1p2 2003DRAGOS COZMA COZMA, D., et al.: Can Simple Doppler Measurements Estimate Interatrial Conduction Time?Prolongation of the interatrial conduction time (ia-CT) is considered an important factor in the pathophysiology of atrial fibrillation (AF) and as a criterion to perform multisite atrial pacing. Measurement of ia-CT requires an electrophysiologic study. The aim of this study was to compare echocardiographic with electrophysiologic measurements to determine if they are correlated. Methods and Results: The study included 32 consecutive patients who underwent electrophysiologic studies. We measured ia-CT between the high right atrium and the distal coronary sinus. In all patients we measured P wave duration, left atrial diameter and area, and ia-CT by Doppler echocardiography was measured as the difference in time intervals between the QRS onset and the tricuspid A wave, and the QRS onset and the mitral A wave (DT). Ia-CT was statistically correlated with DT(r = 0.79, P < 0.0001), but not with P wave duration or left atrial dimensions. Conclusions: Measurement DT may be reliable to estimate ia-CT without invasive procedure. Accordingly, DT could be used as a simple selection criterion when considering patients for atrial resynchronization therapy. (PACE 2003; 26[Pt. II]:436,439) [source] Multiobjective optimization of polymerization reaction of vinyl acetate by genetic algorithm technique with a new replacement criterionPOLYMER ENGINEERING & SCIENCE, Issue 5 2008Maryam Sadi A multiobjective optimization procedure based on genetic algorithm has been developed to determine optimum operational conditions of polymerization reaction. In this article by using a new selection criterion to choose the next generation members with better quality, optimization efficiency is improved and the number of generations to obtain Pareto optimal set reduced. In this proposed method a novel replacement criterion based on ranking level information and proximity of solutions to the Pareto optimal front is used to choose the next generation members. The polymerization of vinyl acetate has been chosen as an example. Two objective functions, which used in this study, are maximization of the weight average molecular weight up to the desired value and minimization of the residual initiator concentration. A Pareto optimal set of objective functions has been obtained by application of a Pareto set filter operator. Furthermore, the influence of genetic algorithm parameters on the efficiency and convergence of genetic algorithm is studied by changing cross over and mutation probabilities. Because of the flexibility and generality of genetic algorithm, this optimization method is a useful technique with lots of potentials in determination of optimum value of operation parameters. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Testing options for the commercialization of abalone selective breeding using bioeconomic simulation modellingAQUACULTURE RESEARCH, Issue 9 2010Nick Robinson Abstract The genetic response and economic benefit from alternative breeding programme designs for blacklip and greenlip abalone (Haliotis rubra and Haliotis laevigata, respectively) were evaluated using a computer simulation model. Two selection criteria were investigated, one used family breeding values for liability to disease challenge test infection and the other used a direct selection of the best performing individuals across families for growth rate. Five scales of breeding programme were tested and the model predicted that if growth rate is the only selection criterion, breeding programmes of a scale using 150 families of each species each generation would result in 12,13% genetic improvement in initial generations and have the greatest beneficial economic impact on the Australian abalone industry of the options tested. The model predicts an average discounted benefit,cost ratio of 48:1, total added discounted benefit of AU$4.90 for each kilogram of abalone produced and nominal economic effect on operating income of over AU$16 million per year after 10 years. If disease resistance is the only selective breeding criterion, 100 families of each species would result in the highest benefit,cost ratio of the options tested, although some genetic gain would need to be sacrificed to reduce inbreeding to acceptable levels in this scenario. A strategy for a stand-alone abalone selective breeding cooperative was also modelled. For a farm of current tank area yielding 100 t year,1, participation is expected to yield over AU$0.7 million in discounted total added production value and annual discounted returns of over AU$0.4 million per annum by year 10. [source] Genetic covariation in production traits of sub-adult black bream Acanthopagrus butcheri after grow-outAQUACULTURE RESEARCH, Issue 11 2005Robert G Doupé Abstract Predicting the suitability and reliability of traits associated with juvenile growth as indirect selection criteria for choosing future broodstock requires accurate and repeatable estimates of genetic (co)variation for growth traits at different ages. We compared juvenile wet weight of black bream Acanthopagrus butcheri (Munro) at 6 months of age with wet weight, dressed weight, fillet yield and gonad weight in tagged individuals at 18 months of age, following 12 months of farm grow-out. Fish survival and tag retention was high, and there was significant among-family variation for all traits. The phenotypic correlations among wet weight, dressed weight and fillet yield at 18 months of age were very high (0.93,0.97) and similar to their genetic correlations (0.96). Importantly, the phenotypic correlations between wet weight at 6 months and wet weight, dressed weight and fillet yield at 18 months were high (0.63,0.65), and so too were their genetic correlations (0.66,0.73), indicating the potential for using wet weight in the hatchery as a selection criterion for improved weight and meat yield of fish at harvest. Gonad weight shared little or no phenotypic or genetic correlation with these other traits, suggesting that selection for faster growing fish will not affect fecundity or sexual maturation rate. It appears, however, that cultured black bream do become sexually mature more rapidly than wild fish, as 78% of all fish harvested in this study had developing or mature gonads, whereas less than 50% of fish in wild populations are reproductively mature by the same age. Precocious sexual development may lead to uncontrolled spawning in grow-out ponds and a potential loss of selection gains. [source] Strain differences in feed efficiency measured as residual feed intake in individually reared rainbow trout, Oncorhynchus mykiss (Walbaum)AQUACULTURE RESEARCH, Issue 7 2005Jeffrey T Silverstein Abstract The efficient use of feed for growth and meat production is important for all animal production industries including aquaculture. Residual feed intake (RFI) is an alternative measure of feed efficiency that has been widely used in livestock production. Residual feed intake was calculated as the difference between intake observed and intake predicted on the basis of a bioenergetics model; a low RFI indicates greater efficiency. Residual feed intake offers some advantages as a selection criterion for improving production efficiency over traditional feed efficiency statistics because it is not a ratio and it typically has a larger coefficient of variation. The RFI of individually reared rainbow trout progeny from six different genetic cross-types was examined for genetic variation. Proximate analysis and nitrogen retention were also evaluated to determine if differences in RFI correlate to differences in body composition and nutrient retention and varied by cross-type. Differences between cross-types indicated a genetic component for RFI, with the most efficient fish of approximately 160 g consuming 0.99 g less and inefficient fish consuming 0.05 g more feed per day than expected. Lower RFI was associated with higher growth rates (r=,0.38, P<0.05) and greater nitrogen retention (r=,0.82 P<0.001). [source] Morphological properties of isolated galaxies vs. isolation criteriaASTRONOMISCHE NACHRICHTEN, Issue 9-10 2009I.B. Vavilova Abstract We studied the morphological properties of isolated galaxies samples in dependence on the isolation parameter and properties of primary catalogs. With this aim we identified the samples of single and isolated galaxies from SDSS DR5 (Single and QIsol) with the 3D Voronoi tessellation method (Elyiv et al. 2009). We found that in comparison with other samples of isolated galaxies, the QIsol sample contains an excess of late-type galaxies, especially with a low luminosity and BCG/Im/Irr morphology. We also showed that the fractions of early type galaxies in QIsol SDSS DR5 sample and samples 2MIG (Karachentseva et al. 2010) and CIG (Karachentseva et al. 1973; Hernandez-Toledo et al. 2008) are in a good agreement (16,19 %), but Allam's (Allam et al. 2005) and Prada's (Prada et al. 2003) SDSS DR1 samples show a higher excess of the early type galaxies that can be explained by the selection criteria and morphology definition method. We found a weak relation between isolation parameter and color index for the Single sample that may indicate that even in the low dense environment the morphology density relation is observed. We conclude that morphological properties of the resulting sample of isolated galaxies are highly dependent on the primary catalogue from which the galaxies were selected. Moreover, the selection criterion is also important but plays a secondary role in the resulting morphological content, color indices distribution and other parameters of the isolated galaxy samples. Only four galaxies are common in the 2MIG, QIsol, and CIG samples, namely UGC5184, UGC6121, UGC8495, and UGC9598, that allows to consider them as really most isolated galaxies (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Variable Selection in the Cox Regression Model with Covariates Missing at RandomBIOMETRICS, Issue 1 2010Ramon I. Garcia Summary We consider variable selection in the Cox regression model (Cox, 1975,,Biometrika,362, 269,276) with covariates missing at random. We investigate the smoothly clipped absolute deviation penalty and adaptive least absolute shrinkage and selection operator (LASSO) penalty, and propose a unified model selection and estimation procedure. A computationally attractive algorithm is developed, which simultaneously optimizes the penalized likelihood function and penalty parameters. We also optimize a model selection criterion, called the,ICQ,statistic (Ibrahim, Zhu, and Tang, 2008,,Journal of the American Statistical Association,103, 1648,1658), to estimate the penalty parameters and show that it consistently selects all important covariates. Simulations are performed to evaluate the finite sample performance of the penalty estimates. Also, two lung cancer data sets are analyzed to demonstrate the proposed methodology. [source] Generalized Hierarchical Multivariate CAR Models for Areal DataBIOMETRICS, Issue 4 2005Xiaoping Jin Summary In the fields of medicine and public health, a common application of areal data models is the study of geographical patterns of disease. When we have several measurements recorded at each spatial location (for example, information on p, 2 diseases from the same population groups or regions), we need to consider multivariate areal data models in order to handle the dependence among the multivariate components as well as the spatial dependence between sites. In this article, we propose a flexible new class of generalized multivariate conditionally autoregressive (GMCAR) models for areal data, and show how it enriches the MCAR class. Our approach differs from earlier ones in that it directly specifies the joint distribution for a multivariate Markov random field (MRF) through the specification of simpler conditional and marginal models. This in turn leads to a significant reduction in the computational burden in hierarchical spatial random effect modeling, where posterior summaries are computed using Markov chain Monte Carlo (MCMC). We compare our approach with existing MCAR models in the literature via simulation, using average mean square error (AMSE) and a convenient hierarchical model selection criterion, the deviance information criterion (DIC; Spiegelhalter et al., 2002, Journal of the Royal Statistical Society, Series B64, 583,639). Finally, we offer a real-data application of our proposed GMCAR approach that models lung and esophagus cancer death rates during 1991,1998 in Minnesota counties. [source] Model Selection in Estimating EquationsBIOMETRICS, Issue 2 2001Wei Pan Summary. Model selection is a necessary step in many practical regression analyses. But for methods based on estimating equations, such as the quasi-likelihood and generalized estimating equation (GEE) approaches, there seem to be few well-studied model selection techniques. In this article, we propose a new model selection criterion that minimizes the expected predictive bias (EPB) of estimating equations. A bootstrap smoothed cross-validation (BCV) estimate of EPB is presented and its performance is assessed via simulation for overdispersed generalized linear models. For illustration, the method is applied to a real data set taken from a study of the development of ewe embryos. [source] Rapid whole monoclonal antibody analysis by mass spectrometry: An Ultra scale-down study of the effect of harvesting by centrifugation on the post-translational modification profile,BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010C.Q. Reid Abstract With the trend towards the generation and production of increasing numbers of complex biopharmaceutical (protein based) products, there is an increased need and requirement to characterize both the product and production process in terms of robustness and reproducibility. This is of particular importance for products from mammalian cell culture which have large molecular structures and more often than not complex post-translational modifications (PTMs) that can impact the efficacy, stability and ultimately the safety of the final product. It is therefore vital to understand how the operating conditions of a bioprocess affect the distribution and make up of these PTMs to ensure a consistent quality and activity in the final product. Here we have characterized a typical bioprocess and determined (a) how the time of harvest from a mammalian cell culture and, (b) through the use of an ultra scale-down mimic how the nature of the primary recovery stages, affect the distribution and make up of the PTMs observed on a recombinant IgG4 monoclonal antibody. In particular we describe the use of rapid whole antibody analysis by mass spectrometry to analyze simultaneously the changes that occur to the cleavage of heavy chain C-terminal lysine residues and the glycosylation pattern, as well as the presence of HL dimers. The time of harvest was found to have a large impact upon the range of glycosylation patterns observed, but not upon C-terminal lysine cleavage. The culture age had a profound impact on the ratio of different glycan moieties found on antibody molecules. The proportion of short glycans increased (e.g., (G0F)2 20,35%), with an associated decrease in the proportion of long glycans with culture age (e.g., (G2F)2 7,4%, and G1F/G2F from 15.2% to 7.8%). Ultra scale-down mimics showed that subsequent processing of these cultures did not change the post-translational modifications investigated, but did increase the proportion of half antibodies present in the process stream. The combination of ultra scale-down methodology and whole antibody analysis by mass spectrometry has demonstrated that the effects of processing on the detailed molecular structure of a monoclonal antibody can be rapidly determined early in the development process. In this study we have demonstrated this analysis to be applicable to critical process design decisions (e.g., time of harvest) in terms of achieving a desired molecular structure, but this approach could also be applied as a selection criterion as to the suitability of a platform process for the preparation of a new drug candidate. Also the methodology provides means for bioprocess engineers to predict at the discovery phase how a bioprocess will impact upon the quality of the final product. Biotechnol. Bioeng. 2010;107: 85,95. © 2010 Wiley Periodicals, Inc. [source] Intracranial tumor surgery in patients >70 years of age: is clinical practice worthwhile or futile?ACTA NEUROLOGICA SCANDINAVICA, Issue 5 2009S. G. Rogne Objectives,,, To study survival and functional outcome after intracranial tumor surgery in elderly patients. Materials and methods,,, This is a retrospective study of 289 consecutive patients of age ,70 years, who underwent primary surgery (resection or biopsy) in the time period 2003,2007 for an intracranial tumor (87 astrocytomas, 79 meningiomas, 62 brain metastases, 33 pituitary adenomas and 28 other tumors). Results,,, The surgical mortality was 2.8%. Overall survival at 6 months, 1, 2 and 5 years was 73%, 57%, 46% and 38% respectively. Histology, pre-operative Eastern Cooperative Oncology Group (ECOG) performance score and resection, as opposed to biopsy, were significantly associated with survival. Gender, age and American Association of Anaesthetists (ASA) score were not significantly related to survival. One-year survival after surgery for astrocytoma, meningioma, brain metastases and pituitary adenoma were 24%, 94%, 31% and 96% respectively. More than 85% of the patients who were alive 6 months after surgery had a stable or improved ECOG score compared with their pre-operative score. Conclusions,,, Surgery for intracranial tumors in selected elderly patients is worthwhile, not futile. Age alone should not be used as a selection criterion for treatment. [source] | ||||||||||||||||||||||