bluuebunny/crossref_metadata_2025_split huggingface dataset:
Female and Male Admission to Graduate School: An Illustrative Inquiry
Authors: Maxwell Scott E. , Jones Lyle V. 
Published: March 2008

Female and male admission rates to four graduate programs at the University of North Carolina at Chapel Hill are compared for 1972–73 and 1973–74. To assess possible sex-related bias in admission, rates are adjusted for applicant qualifications by analysis of covariance and by balancing. Guidelines for choosing between these two techniques are developed. The use of adjustment techniques for these data is shown to be justified in terms of Meehl’s analysis of theex post facto design. Other adjustment procedures, direct and indirect standardization, are critically discussed. The adjusted admission rates reflect, in one case, i.e., for one program and one admission year, a slight advantage for male applicants over females, while in three cases, female applicants were granted a slight advantage over males in admission. In the remaining four cases, there is no evidence that sex of applicant,per se, played a role in admission decisions. Wherever a sex-related advantage is detected, the favored sex is that with the fewer applicants to the program. While the generalization of these results to other programs and other graduate schools is unwarranted, it is appropriate to emphasize the value of applying balancing and/or analysis of covariance to data that may be collected for the purpose of detecting possible discrimination in the selection or evaluation of identifiable population subgroups.
Value-Added Analysis: A Dynamic Approach to the Estimation of Treatment Effects
Authors: Bryk Anthony S. , Weisberg Herbert I. 
Published: March 2008

Randomized experiments are rarely feasible in large-scale educational and social evaluations. Most evaluations are observational studies in which the investigators have very limited control over the assignment of individuals to treatments. Since the effect of an intervention becomes confounded with those of other influences, clear causal inferences are very difficult to obtain. A number of statistical “adjustment” strategies have been suggested in an attempt to remove the bias attributable to these confounding factors. These techniques are based on a static model in which the outcome is a relatively simple function of various inputs, one of which is the treatment. In educational studies, one of the principal “inputs” is generally a measure of the outcome variable prior to the program. Statistical adjustments are based primarily on the observed relationship between these pretest scores and the posttest scores measured after the intervention. An alternative analysis approach is presented in this paper. It focuses explicitly on the fact that an educational treatment typically involves an intervention in a growth process. By modelling this process, it may be possible to estimate expected growth for various treatment groups under “control” conditions. Actual growth can be compared with projected growth to estimate thevalue-added by the program. A very simple model is developed here as a first step toward implementing this approach. The model is applied to a set of data taken from the Head Start Planned Variation Study. The results are compared with a parallel analysis using the analysis of covariance. Discrepancies between the results of the two analyses are examined, and it is suggested that the value-added results are more accurate in this instance.
Models of Environmental Effects on the Development of IQ
Authors: Kadane Joseph B. , McGuire Timothy W. , Sanday Peggy Reeves , Staelin Richard 
Published: March 2008

This paper proposes a number of models of the effects of demographic and environmental factors on IQ and its pattern of change over time. The proposed models are concerned with the determinants of an Individual’s true (but unobserved) IQ and the relationship between measured and true IQ’s. Our analyses are based on data from the school records of a panel of 1, 746 students from the Pittsburgh school system and include demographic and environmental measures as well as IQ test scores at kindergarten, fourth, sixth, and eighth grades. The results indicate that the number of parents living in the household has an important positive effect on IQ at kindergarten that persists over the period of analysis. Number of siblings (measuring both birth order and family size) has an important negative influence on cumulative changes in IQ. Females show faster development until fourth grade; the net difference between the sexes almost completely vanishes by eighth grade. However, the predominant influences on the development of IQ are the socioeconomic status of the student’s parents and peers in school, with SES of peers being the more important. We estimate that roughly half of the difference between the measured eighth grade IQ’s of the average white and black student in our sample may be attributed to differences in their peer and parental SES’s. Finally, we caution that our results may be misleading, since our sample is not from a designed experiment and thus some of the explanatory variables could be correlated with unobserved factors that affect IQ.
A Two-Stage Conditional Estimation Procedure for Unrestricted Latent Class Models
Authors: Macready George B. , Dayton C. Mitchell 
Published: March 2008

A variety of latent class models has been presented during the last 10 years which are restricted forms of a more general class of probability models. Each of these models involves an a priori dependency structure among a set of dichotomously scored tasks that define latent class response patterns across the tasks. In turn, the probabilities related to these latent class patterns along with a set of “Omission” and “intrusion” error rates for each task are the parameters used in defining models within this general class. One problem in using these models is that the defining parameters for a specific model may not be “identifiable.” To deal with this problem, researchers have considered curtailing the form of the model of interest by placing restrictions on the defining parameters. The purpose of this paper is to describe a two-stage conditional estimation procedure which results in reasonable estimates of specific models even though they may be nonidentifiable. This procedure involves the following stages: (a) establishment of initial parameter estimates and (b) step-wise maximum likelihood solutions for latent class probabilities and classification errors with iteration of this process until stable parameter estimates across successive iterations are obtained.
Irt Versus Conventional Equating Methods: A Comparative Study of Scale Stability
Authors: Petersen Nancy S. , Cook Linda L. , Stocking Martha L. 
Published: March 2008

Scale drift for the verbal and mathematical portions of the Scholastic Aptitude Test (SAT) was investigated using linear, equipercentile and item response theory (IRT) equating methods. The linear methods investigated were the Tucker, Levine Equally Reliable and Levine Unequally Reliable models. Three IRT calibration designs were employed. These designs are referred to as (1) concurrent, (2) fixed b’s method, and (3) characteristic curve transformation method. The results of the various equating methods were compared both graphically and analytically. These results indicated that for reasonably parallel tests, linear equating methods perform adequately. However, when tests differ somewhat in content and length, methods based on the three-parameter logistic IRT model lead to greater stability of equating results. Of the conventional equating methods investigated, the Levine Equally Reliable model appears to be the most robust for the type of equating situation used in this study. The IRT method that provided the most stable equating results overall was the concurrent calibration method.
Planned and Post Hoc Comparisons in Tests of Concordance and Discordance forG Groups of Judges
Authors: Serlin Ronald C. , Marascuilo Leonard A. 
Published: March 2008

Statistical procedures for making comparisons on the ranking of a set ofK elements, wines, people, and so forth, have been worked out for the case in which the ranking is done by a single group ofn people. In this special situation, Friedman’s test can be called upon to assess the significance of differences in mean ranking, and Kendall’s coefficient of concordance can be used to measure the level of agreement among the individuals doing the ranking. Unfortunately, the problem of comparingG groups of subjects to determine whether or not they produce the same mean ranking has, until recently, remained unanswered. A procedure was developed for testing two-group concordance by Schucany and Frawley. Hollander and Sethuraman have questioned this procedure and have provided an alternative model for investigating the same problem. It is easy to show that the Schucany and Frawley model tests for positive rank correlation in the mean ranks as an alternative, whereas the Hollander and Sethuraman model tests identity of mean ranks across theK compared elements as the null. In this article, these two models are examined, the criticism is evaluated, and both models are extended to theG group situation. The extension to planned and post hoc comparisons is illustrated using data based on a study described by Marascuilo and Dagenais.
Accounting for Statistical Artifacts in Item Bias Research
Authors: Shepard Lorrie , Camilli Gregory , Williams David M. 
Published: March 2008

Theoretically preferred IRT bias detection procedures were applied to both a mathematics achievement and vocabulary test. The data were from black and white seniors on the High School and Beyond data files. To account for statistical artifacts, each analysis was repeated on randomly equivalent samples of blacks and whites ( n’s = 1,500). Furthermore, to establish a baseline for judging bias indices that might be attributable only to sampling fluctuations, bias analyses were conducted comparing randomly selected groups of whites. To assess the effect of mean group differences on the appearance of bias, pseudo-ethnic groups were created, that is, samples of whites were selected to simulate the average black-white difference. The validity and sensitivity of the IRT bias indices was supported by several findings. A relatively large number of items (10 of 29) on the math test were found to be consistently biased; they were replicated in parallel analyses. The bias indices were substantially smaller in white-white analyses. Furthermore, the indices (with the possible exception of χ2) did not find bias in the pseudo-ethnic comparison. The pattern of between-study correlations showed high consistency for parallel ethnic analyses where bias was plausibly present. Also, the indices met the discriminant validity test—the correlations were low between conditions where bias should not be present. For the math test, where a substantial number of items appeared biased, the results were interpretable. Verbal math problems were systematically more difficult for blacks. Overall, the sums-of-squares statistics (weighted by the inverse of the variance errors) were judged to be the best indices for quantifying ICC differences between groups. Not only were these statistics the most consistent in detecting bias in the ethnic comparisons, but they also intercorrelated the least in situations of no bias.
An Improved Internal Consistency Reliability Estimate
Authors: Cliff Norman 
Published: March 2008

Kuder-Richardson Formula 20 was derived on the assumption that the average covariance between items on different forms is the same as the average covariance on the same form. This formula is considered an underestimate of the parallel form reliability because the average covariance of items with identical difficulty is expected to be higher than the average covariance of items of different difficulty. The proposed coefficient is derived by assuming instead that the average Goodman-Kruskal gamma between items of identical difficulty would be the same as the average for items of different difficulty. Given the average gamma for the present items, this permits an estimate of the covariance between items of identical difficulty. This leads directly to an estimate of the correlation between scores on the present test and those on a form that had an identical distribution of difficulty. Some examples are given.
Perceived Control and Coping in Women Faced with Activity Restriction due to Osteoarthritis: Relations to Anxious and Depressive Symptoms
Authors: Rivard Vicky , Cappeliez Philippe 
Published: March 2008

ABSTRACTThe study focuses on perceived control and coping strategies regarding activity restriction due to osteoarthritis in a sample of older women. Using a cross-sectional design, it examines how these variables, separately and in combination, predict anxious symptoms and depressive symptoms. Perceived control did not predict anxious symptoms, while approach-type coping strategies did. Perceived control and approach-type coping strategies individually predicted depressive symptoms. Higher perceived control in interaction with avoidant-type coping strategies significantly predicted lower depressive symptoms. Overall, the findings suggest that perceived control and coping strategies with regard to activity restriction relate in different ways to anxious symptoms and to depressive symptoms.
Colonization of recent coniferous versus deciduous forest stands by vascular plants at the local scale
Authors: Wulf Monika , Heinken Thilo 
Published: March 2008

Abstract.Questions: 1. Are there differences among species in their preference for coniferous vs. deciduous forest? 2. Are tree and shrub species better colonizers of recent forest stands than herbaceous species? 3. Do colonization patterns of plant species groups depend on tree species composition?Location: Three deciduous and one coniferous recent forest areas in Brandenburg, NE Germany.Methods: In 34 and 21 transects in coniferous and deciduous stands, respectively, we studied the occurrence and percentage cover of vascular plants in a total of 150 plots in ancient stands, 315 in recent stands and 55 at the ecotone. Habitat preference, diaspore weight, generative dispersal potential and clonal extension were used to explain mechanisms of local migration. Regression analysis was conducted to test whether migration distance was related to species’ life‐history traits.Results: 25 species were significantly associated with ancient stands and ten species were significantly more frequent in recent stands. Tree and shrub species were good colonizers of recent coniferous and deciduous stands. In the coniferous stands, all herbaceous species showed a strong dispersal limitation during colonization, whereas in the deciduous stands generalist species may have survived in the grasslands which were present prior to afforestation.Conclusions: The fast colonization of recent stands by trees and shrubs can be explained by their effective dispersal via wind and animals. This, and the comparably efficient migration of herbaceous forest specialists into recent coniferous stands, implies that the conversion of coniferous into deciduous stands adjacent to ancient deciduous forests is promising even without planting of trees.
Development of Industrial Catalysts1A list of symbols used in the text is provided at the end of the chapter.
Authors: Gallei Ewald F. , Hesse Michael , Schwab Ekkehard 
Published: March 2008

Abstract
The sections in this article are

Introduction

Types and Properties of Technical Catalysts

Characterization of Technical Catalysts

In‐Situ
Experiments

High‐Throughput Experimentation (
HTE
)

Identification of Technical Catalysts

Production of Technical Catalysts

Conclusions
Ensemble and Ligand Effects in Metal Catalysis
Authors: Sachtler Wolfgang M. H. 
Published: March 2008

AbstractThe sections in this article areIntroduction: Adsorption Sites on Metal SurfacesDissociative Chemisorption; Ensemble RequirementsThe “Electronic” Ligand EffectPure and “Mixed” Ensembles on Binary AlloysAcknowledgments
Short Contact‐Time Reactors
Authors: Veser Götz 
Published: March 2008

Abstract
The sections in this article are

Introduction

Brief History

Short Contact‐Time Reactions

Hydrogen and Syngas Formation from Methane

Hydrogen and Syngas from Higher Alkanes

Production of Olefins

Production of Oxygenates

Ketenes from Carboxylic Acids

Reaction Mechanisms and Catalysts for
SCTR

Catalysts for Syngas Formation

Syngas Formation: The Reaction Mechanism

Catalysts and Reaction Mechanism for Olefin Production

Catalysts and Reaction Mechanism for Oxygenate Production

Reactor Concepts

Summary and Outlook
Catalytic Membrane Reactors
Authors: Dittmeyer Roland , Caro Jürgen 
Published: March 2008

Abstract
The sections in this article are

Introduction

Types of Membrane Reactor

Catalytic Reactors with Hydrogen‐Selective Membranes

Membrane Types

Organic Polymers

Solid Polymer Electrolytes

Metals

Microporous Membranes

Ceramic Proton Conductors and Cermets

Final Remarks

Selective Removal of Hydrogen

Dehydrogenation

A
Hydrocarbons

B
Alcohols

Water Gas Shift Reaction

Reforming

A
Packed‐Bed Membrane Reformers

B
Fluidized‐Bed Membrane Reformers

C
Microstructured Membrane Reformers

D
Techno‐Economic Evaluation

Selective Supply of Hydrogen

Hydrogenation

Hydroxylation by
In‐Situ
H
2
O
2
Formation

Perspectives

Reactors with Oxygen‐Selective Membranes

Membrane Types

Mixed Oxygen‐Ion‐ and Electron‐Conducting Membranes

Solid Electrolytes for Electrochemical Operation

Membranes for Selective Removal of Oxygenates

Pore Membranes for Non‐Selective Oxygen Feeding

Selective Supply of Oxygen

Production of Pure Oxygen and of Oxygen‐Enriched Air

Partial Oxidation of Methane to Synthesis Gas

Oxidative Dehydrogenation of Light Alkanes to Olefins

Oxidative Coupling of Methane to
C
2
‐Hydrocarbons

Solid Electrolyte Membrane Reactors

Perspectives

Catalytic Reactors with Non‐Selective Membranes

Distributed Feeding through Membranes

Catalytic Membrane Contactors

Gas–Liquid Applications

Liquid–Liquid Applications

Gas–Gas Applications

Perspectives

Design of Catalytic Membrane Modules

Novel Inorganic Membrane Supports

High‐Temperature Membrane Reactor Design

Concluding Remarks
Catalytic Combustion
Authors: Forzatti Pio , Groppi Gianpiero , Cristiani Cinzia 
Published: March 2008

AbstractThe sections in this article areIntroductionBase Concepts and System RequirementsDesign ApproachesFully Catalytic CombustorFuel StagingPartial Catalytic Hybrid CombustorCommercialization Status and PerspectivesFuel‐Rich Catalytic CombustionCatalytic MaterialsHoneycomb SubstrateActive Catalyst LayerPdO‐Based CatalystsMetal‐Substituted Hexaaluminate (HA) CatalystsRich Combustion CatalystsModeling of Catalytic CombustorsStatus and Outlook
Oxidations on Immobilized Molecular Catalysts
Authors: Wahlen Joos , De Vos Dirk 
Published: March 2008

AbstractThe sections in this article areIntroductionImmobilization MethodsAdsorptionIon Pair FormationPhysical EntrapmentCovalent BindingFramework SubstitutionGeneral ConsiderationsOxidantsMetal CatalystsAMetal‐Catalyzed Oxidations with Peroxide OxidantsBMetal‐Catalyzed Oxidations with Molecular OxygenCatalyst SupportsAOrganic SupportsBInorganic SupportsLeachingSelected ExamplesTitaniumManganese and IronAImmobilized Phthalocyanines and Porphyrinsa Olefin Epoxidationb Oxyfunctionalization of Saturated HydrocarbonsBImmobilized Non‐Planar LigandsCobaltAOxidation of ThiolsBOxyfunctionalization of Saturated HydrocarbonsCopperAOxidative Coupling of PhenolsBOxygenation of EnaminesMolybdenumRutheniumAAlcohol OxidationBOlefin Epoxidation and Oxyfunctionalization of Saturated HydrocarbonsTungstenAImmobilization ofWvia Anion ExchangeBImmobilization ofWviaPOWinteractionsOsmiumConcluding Remarks
Review of the Phillips Chromium Catalyst for Ethylene Polymerization
Authors: McDaniel Max P. 
Published: March 2008

AbstractThe year 2001 marked the 50th anniversary of the discovery of the Phillips chromium catalyst, from which today's worldwide high‐density polyethylene industry sprang. Appropriately, during that year the discoverers of this catalyst system, J. Paul Hogan and Robert L. Banks, were inducted into the National Inventors Hall of Fame, in Akron, OH, to join other distinguished inventors spanning two centuries who have shaped our world. This chapter reviews our understanding of the chemistry associated with that catalyst system, which is used globally to produce perhaps half of the world's high‐density polyethylene, and it provides examples of how that chemistry is exploited commercially.
Block Copolymer ‘Stealth’ Nanoparticles for Chemotherapy: Interactions with Blood Cells In Vitro
Authors: Ma Lwin L. , Jie Pan , Venkatraman Subbu S. 
Published: March 2008

AbstractPassive targeting is one of the approaches to reduce the side effects in intravenous chemotherapeutic administration. This is usually achieved by using so‐called ‘stealth’ particles as carriers, such that the particles can avoid uptake by cells of the reticulo endothelial system (RES) and thus enhance their blood lifetime. To date, there have been no studies of the contribution of various factors to the uptake of particles by the RES, although there is general agreement that a hydrophilic particle surface is helpful. In this study, data is presented on the effect of particle size and surface chemistry on the uptake by monocyte cell lines, as well as by cells in whole blood. Block copolymers of hydrophilic poly(ethylene glycol) (PEG) and the hydrophobic poly(L‐lactide) (PLA) have been used to study surface concentration and conformation effects. It is found that diblock copolymers, in general, show the best stealth characteristics, although triblocks with PEG segment lengths above a certain value are also comparable. It is also found that the uptake goes through a minimum with respect to particle size. For the first time, a method is presented to evaluate the relative uptake efficiency of various types of blood cells, using flow cytometry. The observations are related to structural features found on the polymers.
Iridium‐Catalyzed Asymmetric Hydrogenation of Vinyl Ethers
Authors: Zhu Ye , Burgess Kevin 
Published: March 2008

AbstractA carbene‐oxazoline catalyst 1 proved to be an effective catalyst for reduction of an enol ether that the literature suggested could not be hydrogenated effectively by P,N‐Ir catalysts. Thus, a series of ester and alcohol substrates were hydrogenated using catalyst 1. Good to excellent enantioselectivities and high conversions were obtained.
The in vitro antifungal activity of some dithiocarbamate organotin(IV) compounds on Candida albicans— a model for biological interaction of organotin complexes
Authors: Menezes D. C. , Vieira F. T. , de Lima G. M. , Wardell J. L. , Cortés M.E. , Ferreira M. P. , Soares M. A. , Vilas Boas A. 
Published: March 2008

AbstractThe in vitro antifungal activity of the dithiocarbamate organotin complexes [Sn{S2CN(CH2)4}2Cl2] (1), [Sn{S2CN(CH2)4}2Ph2] (2), [Sn{S2CN(CH2)4}Ph3] (3), [Sn{S2CN(CH2)4}2n‐Bu2] (4), [Sn{S2CN(CH2)4}Cy3] {Cy = cyclohexyl} (5), [Sn{S2CN(C2H5)2}2Cl2] (6), [Sn{S2CN(C2H5)2}2Ph2] (7), [Sn{S2CN(C2H5)2}Ph3] (8), [Sn{S2CN(C2H5)2}3Ph] (9) and [Sn{S2CN(C2H5)2}Cy3] (10) has been screened against Candida albicans (ATCC 18804), Candida tropicalis (ATCC 750) and resistant Candida albicans collected from HIV‐positive Brazilian patients with oral candidiasis. All compounds exhibited antifungal activities and complexes 3 and 8 displayed the best results. We have investigated the effect of compounds 1–10 on the cellular activity of the yeast cultures. Changes in mitochondrial function have not been detected. However, all drugs reduced ergosterol biosynthesis. Preliminary studies on DNA integrity indicated that the compounds do not cause gross damage to yeast DNA. The data suggest that these compounds share some mechanisms of action on cell membranes similar to that of polyene but not with azole drugs, normally used in Candida infections. Copyright © 2008 John Wiley & Sons, Ltd.