bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorescence Confocal Polarizing Microscopy of a Fluorescent Bent‐Core Liquid Crystal Exhibiting Polarization Splay Modulated (B7) Structures and Defects
Authors: Deb Rajdeep , Oneill Matt , Rao Nandiraju. V. S. , Clark Noel A. , Smalyukh Ivan I. 
Published: September 2014

AbstractThe B7 phases of bent‐core molecules are polarization splay modulated fluid smectics that exhibit an unusually complex variety of exotic macroscopic structures, textures, and defects visible in polarized light microscopy. Herein we describe optical studies of these structures using fluorescence confocal polarizing microscopy (FCPM) and depolarized transmission optical microscopy to probe their organization in three dimensions. These experiments utilize recently reported fluorescent bent‐core molecules designed to give strong polarized fluorescence. This new bent‐core molecular family provides the means for probing a variety of bent‐core phases and structures by using FCPM and multiphoton fluorescence nonlinear imaging techniques. Comparative textural analysis of the B7 structures obtained using different types of imaging and the corresponding structural models are discussed.
A Theoretical Study of the Interaction of Hydrogen and Oxygen with Palladium or Gold Adsorbed on Pyridine‐Like Nitrogen‐Doped Graphene
Authors: Rangel Eduardo , Magana Luis Fernando , Sansores Luis Enrique 
Published: September 2014

AbstractThe interaction of H2 and O2 molecules in the presence of nitrogen‐doped graphene decorated with either a palladium or gold atom was investigated by using density functional theory. It was found that two hydrogen molecules were adsorbed on the palladium atom. The interaction of these adsorbed hydrogen molecules with two oxygen molecules generates two hydrogen peroxide molecules first through a Eley–Rideal mechanism and then through a Langmuir–Hinshelwood mechanism. The barrier energies for this reaction were small; therefore, we expect that this process may occur spontaneously at room temperature. In the case of gold, a single hydrogen molecule is adsorbed and dissociated on the metal atom. The interaction of the dissociated hydrogen molecule on the surface with one oxygen molecule generates a water molecule. The competitive adsorption between oxygen and hydrogen molecules slightly favors oxygen adsorption.
Diversity of honey stores and their impact on pathogenic bacteria of the honeybee, Apis mellifera
Authors: Erler Silvio , Denner Andreas , Bobiş Otilia , Forsgren Eva , Moritz Robin F. A. 
Published: September 2014

AbstractHoneybee colonies offer an excellent environment for microbial pathogen development. The highest virulent, colony killing, bacterial agents are Paenibacillus larvae causing American foulbrood (AFB), and European foulbrood (EFB) associated bacteria. Besides the innate immune defense, honeybees evolved behavioral defenses to combat infections. Foraging of antimicrobial plant compounds plays a key role for this “social immunity” behavior. Secondary plant metabolites in floral nectar are known for their antimicrobial effects. Yet, these compounds are highly plant specific, and the effects on bee health will depend on the floral origin of the honey produced. As worker bees not only feed themselves, but also the larvae and other colony members, honey is a prime candidate acting as self‐medication agent in honeybee colonies to prevent or decrease infections. Here, we test eight AFB and EFB bacterial strains and the growth inhibitory activity of three honey types. Using a high‐throughput cell growth assay, we show that all honeys have high growth inhibitory activity and the two monofloral honeys appeared to be strain specific. The specificity of the monofloral honeys and the strong antimicrobial potential of the polyfloral honey suggest that the diversity of honeys in the honey stores of a colony may be highly adaptive for its “social immunity” against the highly diverse suite of pathogens encountered in nature. This ecological diversity may therefore operate similar to the well‐known effects of host genetic variance in the arms race between host and parasite.
REVIEW OF PROBLEM SOLVING SKILLS
Authors: Baird Leonard L. 
Published: September 2014

ABSTRACTThis review considers the question as to whether there are generic problem‐solving skills that cut across fields or whether the skills are so embedded within specific fields that they can be identified only within the contexts of those fields. To answer this question, an attempt was made to define both “problems” and their “solution.” Then the evidence for the existence of general problem solving skills that are independent from any specific field was examined. Then the analyses of skills within disciplines were reviewed to see if the skills are common across fields. Finally, the implications of the research for the assessment of problem‐solving skills were discussed. In general, it was concluded that similar skills are used in different fields but that their implementation is so dependent on mastery of the specific fields that any assessment of problem‐solving skills would best be conducted within the fields.
SPANISH TRANSLATION AND FEASIBILITY STUDY OF RANGER RICK'S NATURE MAGAZINE
Authors: Shipman Virginia C. 
Published: September 2014

ABSTRACTThe present study represented the interests of the National Science Foundation, The National Wildlife Federation and Educational Testing Service in instructional materials for students of Hispanic background with limited English language proficiency. The study was designed to (a) evaluate the acceptance, appropriateness, and use of an experimental Spanish edition of Ranger Rick's Nature Magazine; (b) identify similarities and differences in reaction by diverse groups within the Hispanic population; and (c) collect and analyze recommendations from the field test sample for the Spanish edition program materials and services. The findings were based on a large nationwide sample of students that varied on the following characteristics: Hispanic origin (Mexican American, Puerto Rican, and Cuban), type of community (urban, suburban, and rural), family socioeconomic status, grade level (four through eight), and level of Spanish and English proficiency. Information also was provided by school administrative and teaching staff. Data were collected by mailed questionnaires and by both interviews and observation at a sample of the study sites. The results indicated that the approach represented by the Spanish edition of Ranger Rick has merit, well serves a variety of pressing educational needs and should be pursued further. Acceptance of the magazine was high for the various ethnic groups represented. Variability within sites, however, reflected differences in students' Spanish competencies, teachers' attitudes and skills, and the particular sociocultural context.
AN INVESTIGATION OF METHODS FOR REDUCING SAMPLING ERROR IN CERTAIN IRT PROCEDURES*
Authors: Wingersky Marilyn S. , Lord Frederic M. 
Published: September 2014

ABSTRACTThe sampling errors of maximum likelihood estimates of item‐response theory parameters are studied in the case where both people and item parameters are estimated simultaneously. A check on the validity of the standard error formulas is carried out. The effect of varying sample size, test length, and the shape of the ability distribution is investigated. Finally, the effect of anchor‐test length on the standard error of item parameters is studied numerically for the situation, common in equating studies, where two groups of examinees each take a different test form together with the same anchor test. The results encourage the use of rectangular or bimodal ability distributions, also the use of very short anchor tests.
AN EXPLORATORY ANALYSIS OF PERFORMANCE ON THE SAT
Authors: Wainer Howard 
Published: September 2014

ABSTRACTMethods of exploratory data analysis are used to decompose data tables which portray the performance of various ethnic groups on the Scholastic Aptitude Test (the SAT). These analyses show: the size and structure of the differences in performance among the ethnic groups studied, the nature of changes across time, and the interactions between ethnic group membership and time. Suggestions regarding the clear display of results from data in this form are made and illustrated.
ASSESSMENT OF BEGINNING READING: A FRAMEWORK FOR CODING ERROR PATTERNS IN ORAL READING PERFORMANCE
Authors: Chittenden Edward A. 
Published: September 2014

ABSTRACTThis project investigated error patterns in young children's oral reading behaviors for the purpose of constructing a rationale and set of preliminary procedures to code major dimensions in skill acquisition. Audiotaped reading samples, taken from the case study files of 21 children, constituted the raw data. Three performance indicators were analyzed: control of the reading process; selective use of knowledge resources in response to features of text; and strategies in reading as an expression of stylistic preferences. This work is an outgrowth of observational studies of beginning readers, and is intended to contribute to the development of performance‐sample techniques for classroom assessment of reading.
ESTIMATING ABILITY WITH THREE ITEM RESPONSE MODELS WHEN THE MODELS ARE WRONG AND THEIR PARAMETERS ARE INACCURATE
Authors: Jones Douglas H. , Wainer Howard , Kaplan Bruce 
Published: September 2014

ABSTRACTWe investigate the accuracy of the maximum likelihood estimator of ability for the one‐ two‐ and three‐parameter logistic models. This is accomplished by fitting of those models to generated item characteristic curves derived from the Armed Services Vocational Aptitude Battery. The mathematical details as to how this is accomplished and our results are included. Among these results is the finding that the 3‐PL model is the least biased, but that for lower abilities it has both the highest M.S.E. and is the most fragile with respect to sampling fluctuations of the parameter estimates. It is recommended that the current practice of utilizing some method of restricting the variability of parameters continue to be employed (i.e., Bayesian priors, robust estimation, fixing some parameters to be constant).
THE GRAPHICAL DISPLAY OF SIMULATION RESULTS WITH APPLICATIONS TO THE COMPARISON OF ROBUST IRT ESTIMATORS OF ABILITY
Authors: Thissen David , Wainer Howard 
Published: September 2014

ABSTRACTSimulation studies of the performance of (potentially) robust statistical estimators usually proceed by applying each of several estimators to several samples of datasets generated under a variety of circumstances. The estimators which do “best” (have the least bias or MSE or both) under many circumstances are declared “good”. Such studies produce large quantities of numbers, in the form of indices of the performance of the various estimators under various conditions. These numbers form the results of the study, and so must be examined in detail. In our current study of robust IRT ability estimators, tabular presentation of the results has become truly unmanageable; that is, obtaining the numbers or doing the simulation is only part of the problem, understanding the excessively plentiful results is another considerable part. To aid in the digestion of such a collection of numbers, we have turned to multivariate graphical display.
CONJUNCTIVE AND DISJUNCTIVE ITEM RESPONSE FUNCTIONS
Authors: Lord Frederic M. 
Published: September 2014

ABSTRACTGiven that the examinee knows the answer to item i if and only if he knows the answer to both item g and item h, a ‘conjunctive’ item response model is required such that items g, h, and i all have the same mathematical form of response function. Since such items may occur in practice, it is desirable that item response models satisfy this condition. For models with two parameters per item, the most general functional form satisfying this condition is found. A third, ‘guessing’ parameter may be added. The corresponding disjunctive model is also derived.
REDUCED RANK CLASSIFICATION
Authors: Dorans Neil J. 
Published: September 2014

ABSTRACTTwo reduced rank classification procedures, principal components classification and equal weights classification, are described and compared via a simulation study to the standard classification procedure to determine their feasibilities as alternative classification procedures. First, a justification for the development of these two reduced rank procedures is provided. Then, the two reduced rank rules are derived. The simulation design is described in detail. The simulation results demonstrate that the reduced rank procedures are preferable to the standard procedure under certain conditions, i.e., when they appropriately incorporate prior information about population structure into their classification rules. Suggestions for future research are offered.
AN ASSESSMENT OF THE RELATIONSHIP BETWEEN THE ASSUMPTION OF UNIDIMENSIONALITY AND THE QUALITY OF IRT TRUE‐SCORE EQUATING1,2,3
Authors: Cook Linda L. , Dorans Neil J. , Eignor Daniel R. , Petersen Nancy S. 
Published: September 2014

ABSTRACTA strong assumption made by most commonly used item response theory (IRT) models is that the data are unidimensional, i.e., statistical dependence among item scores can be explained by a single ability dimension. One of the major practical applications of item response theory models to testing has been in the area of score equating. This research assesses the relationship between violations of the assumption of unidimensionality and the quality of IRT true‐score equating. First‐order and second‐order factor analyses were conducted on correlation matrices among item parcels. The item parcels were constructed to yield correlation matrices that were amenable to linear factor analyses. The first‐order analyses were employed to assess the effective dimensionality of the item parcel data. Second‐order analyses were employed to test meaningful hypotheses about the structure of the data, hypotheses that were suspected to be pertinent to the quality of equating results. Parcels were constructed for three SAT‐verbal forms and three forms of the Mathematics Level II Achievement test. The quality of IRT true‐score equating was assessed by score scale drift. Scale drift is said to have occurred if the results of equating test form D directly to test form A is not the same as that obtained by equating test form D to test form A through intervening forms B and C. Scale drift was less evident in the Mathematics Level II chain of equatings than it was in the SAT‐verbal chain. The factor analyses uncovered structural similarities and differences across test forms that were consistent with the scale drift results. The dimensionality analyses revealed that the Mathematics Level II item parcels were more nearly unidimensional than the SAT‐verbal item parcels. In addition, the dimensionality analyses revealed that one SAT‐verbal test form and one Mathematics Level II form were each less parallel to the other two forms in their respective equating chains than these other forms were to each other. Refinements in the dimensionality methodology and a more systematic dimensionality assessment are logical extensions of the present research.
SOME PITFALLS ENCOUNTERED WHILE TRYING TO COMPARE STATES ON THEIR SAT SCORES: PAGE AND FEIFS AS AN EXAMPLE*
Authors: Wainer Howard 
Published: September 2014

ABSTRACTPage and Feifs attempt to draw inferences about the relative standing of the states on the basis of their mean SAT scores. They point out that this cannot be done without statistically adjusting for various differences among the states. In this paper we identify five serious errors that they made in their analysis which calls to question the validity of their findings. In addition we describe some plausible paths toward a solution.
A COMPARATIVE STUDY OF CURRICULUM EFFECTS ON THE STABILITY OF IRT AND CONVENTIONAL ITEM PARAMETER ESTIMATES1,2,3
Authors: Cook Linda L. , Eignor Daniel R. , Taft Hessy L. 
Published: September 2014

ABSTRACTOne very practical problem facing practitioners in the area of item response theory (IRT) is how to define the population from which samples will be drawn for parameter estimation purposes. A major concern of individuals interested in using IRT with achievement test data is that such tests have been specifically designed to reflect course content, and students taking the tests at different points in their course work may not constitute samples from the same population. This situation is most likely to exist for large scale admissions testing programs that offer achievement tests, to be used by colleges for admissions and placement purposes, at multiple administrations which span the school year. Students who elect to take the tests at one of the spring administrations typically have recently completed, or are about to complete, a course of instruction in the content area measured by the test, whereas, those electing to take the test at a fall administration may have completed their formal instruction in the content area six to eighteen months prior to taking the test. Because of these curriculum effects, it is quite likely that these two groups of students are not members of the same population, and that item parameter estimates (either IRT or conventional) obtained from say, the group of students who took the test after recently completing their coursework, may not be appropriate when applied to data obtained from students who took the test six months to a year after completing their coursework.The purposes of this study were three‐fold: 1) to examine and compare the stability of IRT item difficulty parameter estimates with conventional item difficulty estimates for a set of items from an admissions testing program Biology achievement test given to a group of students recently completing a biology course and another group of students who, for the most part, had received no formal instruction in the content area from 6 to 18 months prior to taking the test; 2) to assess the impact of the lack of stability of the item difficulty estimates on score equating for both IRT and conventional equating methods; and 3) using confirmatory factor analytic techniques, to assess differences in the factor structures of the set of common items given to the groups of interest in an attempt to determine the specific curriculum effects leading to a lack of stability in the item difficulty estimates.
AN EVALUATION OF THREE APPROXIMATE ITEM RESPONSE THEORY MODELS FOR EQUATING TEST SCORES1
Authors: Marco Gary L. , Wingersky Marilyn S. , Douglass James B. 
Published: September 2014

ABSTRACTThe primary purpose of this study was to determine the extent to which three item response theory (IRT) models could be used to approximate the three‐parameter logistic model in estimating item parameters and in equating test scores. These approximate models were less expensive to apply and in some cases used less data than the full‐blown three‐parameter model.The approximations to the three‐parameter model used in this study were (1) the Rasch one‐parameter model, as operationalized in the BICAL computer program, (2) an approximate three‐parameter logistic model based on grouped data divided into fifths and twentieths, and (3) a modified three‐parameter logistic model with fixed a's and c/s. The LOGIST computer program was used to estimate parameters for the modified three‐parameter model; Quantile, a modified version of LOGIST that accepted coarsely grouped data, was used to estimate item parameters for the approximate three‐parameter model.In the case of the approximate models involving BICAL and LOGIST, results of separate item calibrations were used to place item parameter estimates on the same scale. In the case of the approximate model involving Quantile, a method of scaling the item parameter estimates indirectly through existing SAT scaled scores was used.The data for the study came from a recent study (Petersen, Cook, & Stocking, 1983) of scale stability for the Scholastic Aptitude Test. As in the previous study, this study involved the chain equating of a test to itself through five intermediary forms. The sample consisted of approximately 2,670 cases for each of the SAT forms used.The results of the study were as follows: (1) the item calibrations based on twentieths were closer to the true values and to LOGIST estimates than item calibrations based on fifths; (2) the equating results based on twentieths, however, were not more accurate generally than those based on fifths; (3) the three‐parameter model using coarse groupings yielded highly accurate score conversions in equating a test to itself, more accurate in fact than the full‐blown three‐parameter models studied by Petersen, Cook, and Stocking; and (4) all of the approximate models yielded very accurate equating results. A follow‐up analysis indicated that these unexpected equating results were due in large part to the indirect method used to place item parameter estimates on scale through existing score conversions derived from conventional equating methods. The success of the approximate models raises a question about the adequacy of equating a test to itself as a criterion for evaluating equating results. Further research is recommended before any of the approximate models are used operationally.
ASSESSMENT OF THE DIMENSIONALITY OF NAEP YEAR 15 READING DATA
Authors: Zwick Rebecca 
Published: September 2014

ABSTRACTThe reading data from the 1983–1984 NAEP survey were scaled using a unidimensional item response theory model. To determine whether the responses to the reading items were consistent with unidimensionality, four methods were applied: principal component analysis of phi and tetrachoric correlation matrices; principal component analysis of the image correlation matrix, a method based on the work of Guttman (1953); Bock's full‐information factor analysis (Bock, Gibbons, and Muraki, 1985); and Rosenbaum's (1984a) test of unidimensionality, monotonicity, and conditional independence. Results indicated that it was not unreasonable to regard the reading items as measures of a single dimension.