bluuebunny/crossref_metadata_2025_split huggingface dataset:
Succinate production from xylose‐glucose mixtures using a consortium of engineered Escherichia coli
Authors: Xia Tian , Altman Elliot , Eiteman Mark A. 
Published: September 2014

The conversion of variable sugar mixtures into biochemicals poses a challenge for a single microorganism. For example, succinate has not been effectively generated from mixtures of glucose and xylose. In this work, a consortium of two Escherichia coli strains converted xylose and glucose to succinate in a dual phase aerobic/anaerobic process. First, the optimal pathway from xylose or glucose to succinate was determined by expressing either heterologous pyruvate carboxylase or heterologous adenosine triphosphate‐forming phosphoenol pyruvate (PEP) carboxykinase. Expression of PEP carboxykinase (pck) resulted in higher yield (0.86 g/g) and specific productivity (155 mg/gh) for xylose conversion, while expression of pyruvate carboxylase (pyc) resulted in higher productivity (76 mg/gh) for glucose conversion. Then, processes using consortia of the two optimal xylose‐selective and glucose‐selective strains were designed for two different feed ratios of glucose/xylose. In each case the consortia generated over 40 g/L succinate efficiently with yields greater than 0.90 g succinate/g total sugar. This study demonstrates two advantages of microbial consortia for the conversion of sugar mixtures: each sugar‐to‐product pathway can be optimized independently, and the volumetric consumption rate for each sugar can be controlled independently, for example, by altering the biomass concentration of each consortium member strain.
A COMPARATIVE STUDY OF STANDARD‐SETTING METHODS
Authors: Livingston Samuel A. , Zieky Michael J. 
Published: September 2014

ABSTRACTThe borderline‐group method and the contrasting‐groups method were each compared with Nedelsky's method at four schools and with Angoff's method at another four schools, using tests of basic skills in reading and mathematics. The borderline‐group and contrasting‐groups methods produced similar results when approximately equal numbers of students were classified as masters and nonmasters. The contrasting‐groups passing score was lower than the borderline‐group passing score when masters greatly outnumbered nonmasters; higher when nonmasters outnumbered masters. Results involving the Nedelsky and Angoff methods were not consistent across schools. Passing scores tended to be higher at schools where students were more able.
A STATISTICAL METHOD FOR IDENTIFYING RACIAL OVERREPRESENTATION IN SPECIAL EDUCATION PLACEMENT
Authors: Jones Douglas H. , Bennettand Randy Elliot , Sacks Jerome 
Published: September 2014

ABSTRACTThe discovery of disproportionate minority enrollments in special education classes has been a subject of considerable concern to federal, state, and local education officials alike for the past decade. Because the existence of disproportions is frequently thought to result from discriminatory placement practices on the part of local school districts, many state agencies are implementing methods for detecting and taking action against offending districts. This paper discusses some of the methodological problems inherent in existing methods for determining disparities in special education placement and offers an alternative to presently‐used methods. The alternative offered can be used for the simultaneous comparison of disparity across many districts and several diagnostic categories.
AN EXPLORATORY STUDY OF THE APPLICABILITY OF ITEM RESPONSE THEORY METHODS TO THE GRADUATE MANAGEMENT ADMISSION TEST1
Authors: Kingston Neal , Leary Linda , Wightman Larry 
Published: September 2014

ABSTRACTA necessary prerequisite to the operational use of item response theory (IRT) in any testing program is the investigation of the feasibility of such an approach. This report presents the results of such research for the Graduate Management Admission Test (GMAT).Despite the fact that GMAT data appear to violate a basic assumption of the three‐parameter logistic item response model, local independence, the model was able to replicate accurately the observed item responses. IRT‐based equating was consistent across two randomly selected samples and four selected subpopulations (male, female, younger examinees, and older examinees) and produced converted scores very similar to those produced by the current GMAT equating method — linear section pre‐equating — a method that makes different assumptions than those required by IRT. It appears that for GMAT item types and populations, any effect of the violation of local independence on IRT true‐score equating is negligible.This research has shown IRT equating to be feasible for the GMAT; but, because the local independence assumption of IRT appears to be violated, further experience is needed before other IRT methods — such as optimal test development, using item information, or computerized adaptive testing — could be used for the GMAT.
REGIONAL DEPENDENCE FOR CONTINUOUS BIVARIATE DENSITIES
Authors: Holland Paul W. , Wang Yuchung J. 
Published: September 2014

ABSTRACTWhen the region of support for a continuous bivariate density is not a cartesian product set, the joint distribution cannot be independent. This is closely related to the effects caused by “structural zeros” in two‐way contingency tables. Nonrectangular regions of support for continuous densities are analogous to the incomplete two‐way tables. Quasi‐independence is introduced to replace independence. A measure of association to quantify the degree of dependence due to region is defined, discussed, and applied to several examples.
CATS, TESTLETS, AND TEST CONSTRUCTION: A RATIONALE FOR PUTTING TEST DEVELOPERS BACK INTO CAT
Authors: Wainer Howard , Kiely Gerard L. 
Published: September 2014

ABSTRACTIt is observed that many sorts of difficulties preclude the uneventful construction of tests by a computerized algorithm, such as those currently in favor in Computerized Adaptive Testing (CAT). In this essay we discuss a number of these problems as well as some possible avenues of solution. We conclude with the development of the ‘testlet’, a bundle of items that can be arranged either hierarchically or linearly, which maintains the efficiency of an adaptive test while simultaneously keeping the quality control of test construction that is only possible currently with careful expert scrutiny.
THE POTENTIAL DUAL EFFECT OF CONTEXT EFFECTS AND SCORE LEVEL EFFECTS ON THE ASSIGNMENT OF SCORES TO ESSAYS
Authors: Paden Patricia A. 
Published: September 2014

ABSTRACTThis paper represents a systematic treatment of the potential dual effect of the context in which an essay is reread and the previously assigned score (value) of that essay on the subsequently assigned essay score. This effect is theorized in a formula referred to as “essay score change” (ESC). Examples of the possible utility of the ESC index are outlined. Tentative hypotheses for investigating and interpreting possible essay score change in light of potential dual effects of context and score level are discussed.
APPLICATION OF A NEW GOODNESS‐OF‐FIT PLOT PROCEDURE TO SAT AND TOEFL ITEM TYPE DATA1,2,3
Authors: Eignor Daniel R. , Golub‐Smith Marna , Wingersky Marilyn S. 
Published: September 2014

ABSTRACTThe three‐parameter logistic IRT model is currently being used for equating purposes with data from multiple administrations of two testing programs at ETS: the Admissions Testing Program Scholastic Aptitude Test (SAT) and the Test of English as a Foreign Language (TOEFL). Users of the model in these two testing programs have generally assessed goodness of fit of the model to test items by looking at item‐estimated ability regression plots. This procedure tends to be fairly subjective and quite time consuming, and as a result, little useful aggregate data have been assessed that would shed light on which SAT‐Verbal, SAT‐Mathematical, and TOEFL item types are better or more poorly fit by the model.The purposes of this study were two‐fold: 1) to systematically study the fit of the three‐parameter logistic model to SAT and TOEFL item type data, using a fit statistic formed by grouping on estimated ability and a newly suggested normal probability plot procedure; and 2) to determine the degree of consistency that can be expected when assessing lack of fit of the three‐parameter model using the fit statistic formed by grouping on estimated ability and a newly suggested fit statistic which is formed by grouping an observed number‐right score.
THE IMPACT OF DIFFERENT ABILITY DISTRIBUTIONS ON IRT PREEQUATING1,2,3
Authors: Stocking Martha L. , Eignor Daniel R. 
Published: September 2014

ABSTRACTItem response theory preequating depends upon item parameter estimate invariance. The impact of differences in true ability on the invariance properties of item parameter estimates was studied with simulated data. Using real SAT‐mathematical data that had produced unsatisfactory preequating results to suggest hypotheses, three explanatory models were investigated: 1) differences in mean true ability, 2) a certain type of multidimensionality, and 3) a combination of differences in mean true ability and multidimensionality. This latter model produced results consistent with the real data.
HANDICAPPED APPLICANTS TO COLLEGE: AN ANALYSIS OF ADMISSIONS DECISIONS
Authors: Willingham Warren W. 
Published: September 2014

ABSTRACTFederal regulations protect the rights of handicapped students regarding admissions testing and the admissions process generally. The purpose of this study was to compare admissions decisions of handicapped and nonhandicapped applicants who have comparable Scholastic Aptitude Test (SAT) scores and high school grades (HSG). The main finding was that handicapped applicants were admitted on much the same basis as nonhandicapped applicants, but there were exceptions that favored hearing impaired applicants, disfavored small groups of visually impaired and physically handicapped applicants to small institutions, and disfavored learning disabled applicants to a small degree. The results appeared inconsistent with the assumption that colleges give special attention to flagged test scores of handicapped applicants.
SAT TESTING TIME FOR STUDENTS WITH DISABILITIES
Authors: Packer Jaclyn 
Published: September 2014

ABSTRACTThis study examined the amount of time used by disabled students to take special administrations of the SAT offered by the College Board's ATP Services for Handicapped Students. It also investigated the relationship between length of time taken and scores achieved.Timing data on groups of students were examined, both by disability and by the version of the test taken (braille, cassette, large type or regular type). Results showed that disabled students who were tested over the four years from 1979 to 1983 took considerably more time to complete the SAT than non‐disabled students. Hearing impaired students taking a regular version of the test took the smallest amount of time, averaging 3.7 hours, while visually impaired students taking a cassette version averaged 5.4 hours and those taking a braille version averaged 6.0 hours. Physically disabled and learning disabled students averaged between 4.3 and 4.7 hours.Time spent on each section of the SAT (two verbal sections, two math sections and the Test of Standard Written English) was also investigated, although those numbers did not differ substantially from total timing data.The relationship between SAT test scores and the amount of time spent on the verbal and math section of the test was investigated as well. Results showed that physically disabled and visually impaired students who spent more time on the verbal sections of the SAT achieved lower verbal scores than those who spent less time, while the opposite was true for the verbal scores of hearing‐impaired and learning‐disabled students. However, for the math sections of the SAT, students in all disabled groups who spent more time tended to achieve higher math scores.
THE INTERACTION OF STUDENT MAJOR‐FIELD GROUP AND TEXT CONTENT IN TOEFL READING COMPREHENSION
Authors: Hale Gordon A. 
Published: September 2014

ABSTRACTIn light of the current emphasis on English for specific purposes, it was hypothesized that a student's major‐field area interacts with the text content in determining performance on TOEFL reading passages. To assess this possibility, the present study examined performance on the reading passages in TOEFL® forms used in four operational test administrations.The results supported the study's hypothesis, as students in the two key major‐field groups, the humanities/social sciences and the biological/physical sciences, performed significantly better on passages related to their own groups than on other passages, for three of the four test forms examined.Although the hypothesized interaction was statistically significant for most of the test forms, however, the effect was relatively small, as expressed in terms of points on the TOEFL scale. Thus, a distinction must be drawn between the practical significance and the statistical significance of the interaction effect. Practically, the effect appears to be relatively small with typical TOEFL reading passages, perhaps because they are drawn from general readings rather than specialized textbooks. Statistically, however, the present results showed the effect to be a reliable phenomenon, even if relatively small in magnitude, thus supporting the theoretical view that a student's major‐field area interrelates with the text content in determining reading performance.
RELATIONSHIP BETWEEN ITEM CHARACTERISTICS AND AN INDEX OF DIFFERENTIAL ITEM FUNCTIONING (DIF) FOR THE FOUR GRE VERBAL ITEM TYPES
Authors: Freedle Roy , Kostin Irene 
Published: September 2014

ABSTRACTTwo studies are reported. The first examined the factors that predict differences in item responses of two populations (Black and matched White examinees) to GRE analogies. Three factors were found to independently predict differential item responses of these two groups to 234 GRE analogy items: (1) item difficulty, (2) analogy stems with a part/whole relationship and (3) and analogy stems with an “attribute” relationship. An independent sample of 220 SAT analogy items was found to yield very similar results, especially for item difficulty and part/whole relationships. For both GRE and SAT analogies, Black examinees were found to do differentially better than matched White examinees on the hard analogy items.Since item difficulty was found to be the most important predictor variable in Study I, Study II explored the possible importance of item difficulty as a predictor of differential item responses of Black versus matched White examinees for three other verbal item types of both the GRE and SAT tests (these types were antonyms, sentence completions, and reading comprehension items). Item difficulty was found to be an important predictor of the observed differences. An overview of the results suggests that the amount of verbal context might be an important determinant of the magnitude of the relationship between item difficulty and differential performance of Black versus matched White examinees. That is, analogies and antonyms (which have minimal verbal context) produced a stronger correlation of difficulty with differential ethnic performance than did sentence completion and reading comprehension items. This was found for both the GRE and SAT verbal item types. Several hypotheses are advanced to account for some of the observed ethnic differences.
AN ANALYSIS OF TEST WRITERS' EXPERTISE: MODELING ANALOGY ITEM DIFFICULTY
Authors: Enright Mary K. , Bejar Isaac I. 
Published: September 2014

ABSTRACTIn this study, the ability of test development staff to predict the difficulty of analogy items was explored. The nature of the item attributes that contributed to test writers' predictions of difficulty as well as actual item difficulty was also investigated. The expert test writers studied were quite good at predicting item difficulty. Item attributes such as vocabulary difficulty and rationale difficulty contributed to item difficulty. However, a statistical model of item difficulty did not capture all the information that test writers used to judge item difficulty. This research contributes to the construct validation of tests in two ways. First, identification of some item attributes that are associated with item difficulty clarifies what skills and processes are likely to be involved in solving analogies. Secondly, the expertise of test writers, a crucial ingredient in ensuring the validity of the test, is demonstrated.
AN EXAMINATION OF THE RELATIONSHIPS OF ACADEMIC COURSEWORK WITH ADMISSIONS TEST PERFORMANCE
Authors: Morgan Rick 
Published: September 2014

ABSTRACTThe redesigned Student Descriptive Questionnaire (SDQ) provides a great deal of background information about examinees sitting for the Scholastic Aptitude Test (SAT). One set of questions focuses on the number of years and types of courses in the students' academic background. This information makes it possible to explore the relationships between coursework and performance on the SAT. This study used data from the 1987 National Sample Tape, which contains SDQ responses and score information from 100,000 seniors in the class of 1987. The analyses examined the relationships between both the Admissions Testing Program (ATP) SAT and Achievement Test scores and the type and level of coursework in six academic areas. In order to provide a more accurate representation of these relationships, the data were adjusted to account for differences related to student academic achievement. The results show that coursework in the disciplines of mathematics, natural science, and foreign languages has the strongest adjusted relationships with SAT‐mathematical scores. SAT‐verbal scores appear to be most strongly related to the number of years of foreign language coursework. These relationships are generally consistent across ethnic groups and income levels. However, it appears that the relationships are stronger for students with higher grade‐point averages. The specific courses that seem to be most strongly related to SAT performance are upper‐level courses in mathematics, natural science, and foreign languages. The specific course relationships appear stronger for male than for female examinees. An analysis of Achievement Test data again indicates that upper‐level coursework in the three previously mentioned academic areas is most strongly related to performance on the Achievement Tests. All the research findings must be qualified because the study was exploratory. Student participation in the various courses was based solely on the motivation and the opportunity of the students to take the courses. As a result of this self‐selection, causal interpretations of the results are not appropriate.
ACCOUNTING FOR RANDOM RESPONDING AT THE END OF THE TEST IN ASSESSING SPEEDEDNESS ON THE TEST OF ENGLISH AS A FOREIGN LANGUAGE
Authors: Secolsky Charles 
Published: September 2014

ABSTRACTThe usual assessment of speededness for rights‐only scored tests such as the Test of English as a Foreign Language (TOEFL) does not account for the possibility that examinees respond in a random or patterned fashion to the items at the end of the test as the time limit approaches. Therefore, for TOEFL, speededness measures that are based only on the number of items not reached may underestimate the degree to which the test is actually speeded.The present study represented an attempt to determine if Sections 2 and 3 of TOEFL are truly speeded according to established criteria. Two exploratory techniques employing regression analyses were used in an attempt to account for the possibility that examinees responded randomly or in a patterned fashion to unconsidered items at the end of each section. One technique provided an estimate of the degree to which all examinees truly reached the 75 percent point on the sections. The second technique provided an estimate of the degree to which examinees truly completed the last set of items. Support for the results was obtained from an examination of the number of items not reached and the number of items at the end of the sections to which examinees responded in a patterned fashion. The findings are limited to the extent that one can attribute items not reached and patterned responding to the effect of speededness.Four administrations of TOEFL were studied: two non‐pretest administrations and two longer pretest administrations. The results suggest that Section 3 for pretest administrations may be slightly speeded. It is recommended that more observational or survey methods be used to confirm this finding. If the finding is confirmed, it would be recommended that the TOEFL program investigate ways to increase the amount of time allotted per item.
The feasibility and benefits of using volumetric arc therapy in patients with brain metastases: a systematic review
Authors: Andrevska Adriana , Knight Kellie A. , Sale Charlotte A. 
Published: September 2014

AbstractIntroductionRadiotherapy management of patients with brain metastases most commonly involve a whole‐brain radiation therapy (WBRT) regime, as well as newer techniques such as stereotactic radiosurgery (SRS) and intensity modulated radiotherapy (IMRT). The long treatment times incurred by these techniques indicates the need for a novel technique that has shorter treatment times, whilst still producing highly conformal treatment with the potential to deliver escalated doses to the target area. Volumetric modulated arc therapy (VMAT) is a dynamic, highly conformal technique that may deliver high doses of radiation through a single gantry arc and reduce overall treatment times. The aim of this systematic review is to determine the feasibility and benefits of VMAT treatment in regard to overall survival rates and local control in patients with brain metastases, in comparison with patients treated with WBRT, SRS and IMRT.MethodsA search of the literature identified 23 articles for the purpose of this review. Articles were included on the basis they were human‐based studies, with sample sizes of more than five patients who were receiving treatment for 1–10 metastatic brain lesions.ResultsVMAT was found to be highly conformal, have a reduced treatment delivery time and incurred no significant toxicities in comparison with WBRT, SRS and IMRT.ConclusionCompared to other treatment techniques, VMAT proved to have fewer toxicities than conventional WBRT, shorter treatment times than SRS and similar dose distributions to IMRT plans. Future prospective studies are needed to accurately assess the prognostic benefits of VMAT as well as the occurrence of late toxicities.