bluuebunny/crossref_metadata_2025 huggingface dataset:
Online hot event discovery based on Association Link Network
Authors: Liu Yang , Luo Xiangfeng , Xuan Junyu
Published: September 2014

Online hot event discovery has become a flourishing frontier where online document streams are monitored to discover newly occurring events or assigned to previously detected events. However, hot events have the nature to evolve, and their inherent topically related words are also likely to evolve. It makes event discovery a challenging task for traditional‐mining approaches. Combining word association and semantic community, Association Link Network (ALN) organizes the loosely distributed associated resources. This paper presents an ALN‐based novel online hot event discovery approach. Technically, this approach is enacted around three stages. In the first stage, we extract significant features to represent the content of each document from the online document stream. During the second stage, we classify the online document stream into topically related detected events considering event evolution in the form of ALN. At the third stage, we create an ALN‐based event detection algorithm, which is used to timely discover newly occurring hot events. The online datasets used in our empirical studies are acquired from Baidu News, which spans a range of 1315 hot events and 236,300 documents. Experimental results demonstrate the hot events discovery ability with respect to high accuracy, good scalability, and short runtime. Copyright © 2014 John Wiley & Sons, Ltd.
Concluding the Amyloid Formation Pathway of a Coiled‐Coil‐Based Peptide from the Size of the Critical Nucleus
Authors: Gerling Ulla I. M. , Miettinen Markus S. , Koksch Beate
Published: September 2014

The size of the critical nucleus acting as intermediate in the amyloid formation of a model peptide is calculated. The theoretical approach is based on experimentally determined amyloid formation rates and gives new insights into the amyloid formation pathway.
The Electronic Structures of Small Nin (n=2–4) Clusters and Their Interactions with Ethylene and Triplet Oxygen: A Theoretical Study
Authors: Pakiari Ali H. , Pahlavan Farideh
Published: September 2014

Density functional theory (DFT) calculations of small nickel clusters and their interacting systems are carried out using the BLYP and B97‐2 methods, after DFT calibration. All bare nickel clusters in this study have high multiplicities and are paramagnetic. Our results for the interactions between ethylene and oxygen with Nin (n=2–4) clusters at different adsorption modes show that for ethylene, π‐orientation is preferred, and that oxygen adsorption in a bridge mode is stronger than on‐top coordination. Vibrational frequency analysis reveals that the vibrational modes of ethylene π‐coordinated to nickel clusters converge toward the corresponding value for surface‐bound ethylene, as the cluster size increases from two to four, showing that finite clusters can be used as localized models for ligand adsorption on nickel surfaces. We also calculate DFT global reactivity descriptors, chemical potential and hardness, and use these to predict the relative stability and reactivity of each bare cluster.
Ring Currents in Benzo‐ and Benzocyclobutadieno‐Annelated Biphenylene Derivatives
Authors: Radenković Slavko , Tošović Jelena , Havenith Remco W. A. , Bultinck Patrick
Published: September 2014

The effect of benzo and benzocyclobutadieno annelation on the current density induced in a series of biphenylene derivatives is examined at the B3LYP/cc‐pVDZ level of theory, by using the CTOCD‐DZ method. Angular benzo annelation increases, whereas linear benzo annelation decreases the intensity of paratropic (antiaromatic) current density along the four‐membered ring of biphenylene. The opposite effect is found for benzocyclobutadieno annelation. It is shown that the extent of local aromaticity of the four‐membered ring in biphenylene congeners can vary from highly antiaromatic to nonaromatic, as a result of different modes of annelation.
Use of capillary electrophoresis as a versatile tool to measure interaction constants between a KDR‐binding PEGylated lipopeptide and pegylated phospholipid micelles
Authors: Poitevin Martine , Tranquart François , Cherkaoui Samir
Published: September 2014

In the frame of our molecular imaging activities, a PEGylated lipopeptide has been developed as a specific ligand for the human vascular endothelial growth factor receptor 2, which is considered as one of the important molecular marker of angiogenesis. In this study, the potential of affinity capillary electrophoresis (ACE) is evaluated to measure the interactions of an active PEGylated lipopeptide, its hydrolysis product and its precursor consisting of a peptide structure with different micelles including Brij‐35, Tween‐20, and pegylated phospholipids. Given the amphiphilic structure of the PEGylated lipopeptide, a MEKC method allowing the simultaneous separation of the compounds of interest was set up, using low percentages of acetonitrile. Analytes were resolved using a BGE consisting of 100 mM borate buffer pH 9.0, 1 mM Brij, and 25% acetonitrile. Optimized conditions were then used to perform ACE experiments. The affinity constants of the analytes with the micelles were calculated on the basis of their mobility decrease when surfactant concentration increased in the electrolyte. The use of different linearization models to estimate affinity constants was discussed and comparison of different surfactants was reported. PEGylated lipopeptide interacted more strongly with pegylated phospholipid micelles than with Brij‐35 or Tween‐20. Moreover, it is likely that the chemical structure of the compounds, and particularly the lipidic part of the molecules, significantly affects the interaction with micelles. In conclusion, the ACE method can be readily applied to investigate interactions of our targeting lipopeptides with various micelles currently used for the preparation of pharmaceutical vehicles.
Show Me Your Friends, and I Shall Show You Who You Are: The Way Attachment and Social Comparisons Influence Body Dissatisfaction
Authors: Lev‐Ari Lilac , Baumgarten‐Katz Inbar , Zohar Ada H.
Published: September 2014

Women with attachment insecurity have greater eating disorder symptoms and poorer prognosis. Socio‐cultural agents, such as peers and family, are predictive of the development of body image dissatisfaction (BID). The present study examines the association of insecure attachment styles and direct and indirect social comparisons of body image to women's BID and drive to thinness. Two hundred and eighty three women aged 18–42 years completed online self‐reports concerning attachment styles, body mass index (BMI), drive for thinness, body image satisfaction, the Figure Rating Scale (FRS), as well as a modified FRS comparing self to mother, to sister closest in age and to best friend. Hierarchical Linear Models reveal that anxious‐ambivalent, but not avoidant attachment style, along with indirect and direct comparisons to best friend and to sister influence drive for thinness and body dissatisfaction, even after controlling for BMI and age. Of all social comparisons, feeling one's best friend is thinner than yourself is the most detrimental to body ideal. Copyright © 2014 John Wiley & Sons, Ltd and Eating Disorders Association.
Temporal and spatial variation of infilling processes in a landslide scar in a steep mountainous region, Japan
Authors: Imaizumi Fumitoshi , Sidle Roy C. , Togari‐Ohta Asako , Shimamura Makoto
Published: September 2014

The duration of the soil‐depth recovery needed for reoccurrence of shallow colluvial landslides at a given site in humid regions is much longer than the return period of rainfall needed to generate sufficient pore water pressure to initiate a landslide. Knowledge of the rate of change in soil depth in landslide scars is therefore necessary to evaluate return intervals of landslides. Spatial variation in sediment transport at the Kumanodaira landslide scar in central Japan was investigated by field observations. Spatial distribution of the rate of change in soil depth was estimated using sediment transport data and geographic information system (GIS) analysis. Observations revealed that the timing of sediment transport differed for shallow and deep soil layers. Near‐surface sediment transport (mostly dry ravel and some shallow soil creep at depths ≤0·05 m) measured in sediment traps was active in winter and early spring and was affected by freezing–thawing; soil creep of subsoil (i.e. >0·05 m), monitored by strain probes, was active in summer and autumn when precipitation was abundant. Near‐surface sediment flux was estimated by a power law function of slope gradient. Deeper soil creep was more affected by relative location to the landslide scar, which influences soil depth, than by slope gradient. Our study indicated that the rate of soil‐depth recovery is high just below the head scarp of the landslide. Abrupt changes in the longitudinal slope topography immediately above, within and just below the head scarp became smoother with time due to degradation proximate to the landslide head scarp and flanks, as well as aggradation just below the head scarp. Copyright © 2014 John Wiley & Sons, Ltd.
Interhemispheric somatosensory differences in chronic pain reflect abnormality of the Healthy side
Authors: Di Pietro Flavia , Stanton Tasha R , Moseley G. Lorimer , Lotze Martin , McAuley James H
Published: September 2014

It is widely accepted that complex regional pain syndrome (CRPS) is associated with shrinkage of the primary somatosensory cortex (S1) representation of the affected limb. However, supporting evidence is surprisingly limited and may be compromised by high risk of bias. This study compared the S1 spatial representation of the hand in 17 patients with upper‐limb CRPS to 16 healthy controls, using functional MRI. Innocuous vibration was delivered to digits one (D1) and five (D5) in a block‐design. Resultant activation maxima were located within a bilateral S1 mask, determined a priori. Distance between D1 and D5 activation maxima, calculated for both hands, was used as a measure of S1 representation. Analyses were blinded to group and hand. In patients, S1 representation was smaller for the affected hand than it was for the healthy hand (t(11) = 2.02, P = 0.03), as predicted. However, S1 representation of the affected hand was no different to that of either hand in controls. Critically, S1 representation of the healthy hand of patients was larger than that of controls' hands. CRPS seems to be associated with an enlarged representation of the healthy hand, not a smaller representation of the affected hand. These findings raise important questions about neuroplasticity in CRPS. Hum Brain Mapp 36:508–518, 2015. © 2014 Wiley Periodicals, Inc.
ASSESSMENT IN CONTEXT: APPRAISING STUDENT PERFORMANCE IN RELATION TO INSTRUCTIONAL QUALITY
Authors: Messick Samuel
Published: September 2014

As part of an American Educational Research Association Symposium reporting the findings of the National Academy of Sciences (NAS) panel on placing children in special education, this paper discusses the implications of the panel's conclusions for exemplary assessment practices in special education and, indeed, for the very role of assessment in special education. When confronted with the central problem of over‐representation of minority children and males in programs for educable mentally retarded students, the NAS panel responded not with solutions focussing on the direct reduction of disproportion per se – which tend to be simplistic in merely transferring the problem to other parts of the educational system – but rather with solutions focussing on deeper educational issues underlying disproportionate placement, such as the validity of assessment of student functional needs and the quality of services that should be provided.

After first analyzing the three primary issues underlying the policy conflict between equal protection from the harm of separate placement and entitlement to needed services – namely, the quality of the regular instruction to which referred students were exposed, the validity of assessment of student functional needs, and the quality of the special education provided – the panel recommended two major components for special education assessment: (1) for entrance or placement in special education, a two‐phase comprehensive assessment of student performance in relation to the quality of regular instruction received; (2) for exit from or retention in special education, the assessment of special education students' progress toward relevant academic goals, or the lack thereof, in relation to the quality of special instruction received. Thus, student educational progress emerges as the touchstone for equity in special education.
A COMPARATIVE STUDY OF METHODS OF EQUATING TOEFL TEST SCORES
Authors: Hicks Marilyn M.
Published: September 2014

Six methods of equating TOEFL test scores for samples consisting of the usual groups of examinees tested at each TOEFL administration, and groups of examinees controlled for native language representation were evaluated in terms of scale stability. The equating methods included three IRT variants (fixed b's scaling, a one‐parameter model in which a‐ and c‐parameters were fixed at constant values, and a model in which all three parameters were re‐estimated), and three conventional equating methods (Tucker, Levine and equipercentile). The equating methods were applied to Section II, Structure and Written Expression, and Section III, Reading Comprehension and Vocabulary. For the regular group of examinees, fixed b's IRT equating exhibited the greatest scale stability for both sections with the one‐parameter IRT model and Tucker linear equating following in that order. For most equating methods, controlling for native language resulted in increased scale stability relative to the regular group for Section II, but produced more error in Section III. This interaction between Section III and the controlled group may be related to the differential performance observed among language groups on Section III in previous studies. The results of this study supported continued use of fixed b's scaling for TOEFL data using a random sample of examinees from the total testing group.
AN EXAMINATION OF THE ASSUMPTION THAT THE EQUATING OF PARALLEL FORMS IS POPULATION‐INDEPENDENT
Authors: Angoff William H. , Cowell William R.
Published: September 2014

Linear and equipercentile conversions were developed relating Forms 3DGR1 and 3DGR3 of the homogeneous GRE quantitative test and the specially constituted heterogeneous GRE verbal‐plus‐quantitative test, using randomly equivalent populations of about 13,500 cases taking each form, drawn from the entire candidate group tested in the regular October 1981 administration of the Graduate Record Examinations. For purposes of this study these samples of 13,500 cases were taken as representing their respective total populations, and the conversions based on them were taken as “population conversions.” Empirical standard errors of equating were then developed for samples of 1,000 by drawing 100 samples of that size from each of the two base populations and calculating the variance error of equated scores on Form D1 (i.e., 3DGR1) for each successive raw score on Form D3 (i.e., 3DGR3) and fitting a second‐degree equation to those variance errors. Samples of 1,000 cases taking each form were then selected at random from specially defined subpopulations homogeneous with respect to sex, race, field of study, and level of performance (the last of these defined by scores on the GRE analytical test) and used as the basis of additional conversions between the two test forms.

Departures of the conversions based on each of these specially selected samples from the population conversion were calculated and evaluated in terms of the standard error of equating at five selected raw score points on Form D3, adjusted for the disparity between the means, as well as the three higher moments–variance, skewness, and kurtosis–for these subpopulations and the corresponding moments of the total populations.

The results of this phase of the study showed that the conversions for the samples drawn from the Physical Science subpopulation differed significantly from that of the total population. When, in the second phase of the study, the appropriate adjustments for the moments were made, it was found that the Physical Sciences conversions fell clearly in line for the homogeneous GRE quantitative test, but not quite so clearly for the heterogeneous GRE verbal‐plus‐quantitative test. The conversions for all other subpopulation samples were acceptably within range of the population conversion. It was concluded that the assumption of population‐independence for equating is supportable for homogeneous tests but, because of evidence of nonparallelism between the two forms, the assumption is not as clearly established by the data of this study for heterogeneous tests.
NATIONAL CHANGES IN SPATIAL‐VISUAL ABILITY FROM 1960 TO 1980
Authors: Hilton Thomas L.
Published: September 2014

In both 1960 and 1980, the same test of spatial‐visual ability was given to national probability samples of high school seniors in the United States. The students in 1960 were participants in Project TALENT and in 1980 were participants in High School and Beyond. In addition, a reading comprehension test was given to the 1960 students that subsequently was equated to a similar reading test given to the 1980 seniors. In 1960 the males had substantially higher scores in visualization and slightly higher scores in reading. Between 1960 and 1980 all means scores declined but substantially more so in visualization. However, the gap between males and females narrowed, particularly in visualization. In the absence of a clear explanation, the author attributes the general decline primarily to less student attrition in 1980 and the differential decline to convergence in the experiences of males and females.
THE ONCE AND FUTURE ISSUES OF VALIDITY: ASSESSING THE MEANING AND CONSEQUENCES OF MEASUREMENT1
Authors: Messick Samuel
Published: September 2014

A unified view of test validity is propounded that stresses both the existing evidence for and the potential consequences of test interpretation and use. The thrust of this unified view is that appropriateness, meaningfulness, and usefulness of score‐based inferences are inseparable and that the unifying force is empirically‐grounded construct interpretation. Evidence and theoretical rationales are examined indicating that construct interpretation undergirds all score‐based inferences – not just those related to interpretive meaningfulness but also the content‐ and criterion‐related inferences specific to applied decisions and actions based on test scores.
TEST ANXIETY AND THE GRE GENERAL TEST
Authors: Powers Donald E.
Published: September 2014

A survey was designed and administered to a large, stratified random sample of GRE test takers in order to:

provide baseline data regarding the prevalence and severity of test anxiety among GRE test takers

determine the relationship of self‐reported test anxiety to GRE test performance and to examinees' knowledge/perceptions of selected aspects of GRE test taking and graduate admissions, and

obtain GRE test takers' assessments of the contribution of various factors to test anxiety, as well as suggestions for minimizing test anxiety.

The survey instrument included a test anxiety inventory as well as other questions seeking information about examinees' perceptions of various aspects of GRE test taking and graduate admissions. Minority test takers in each of seven ethnic or racial categories were oversampled.

A significant proportion of GRE test takers report that they experience at least a moderate degree of test anxiety, and some report relatively severe anxiety. On average, however, GRE examinees do not appear to be substantially more anxious about GRE test taking than about a number of other evaluative situations.

Two aspects of test anxiety–worry, i.e., cognitive concern over test performance, and emotionality, i.e., reports of physiological reactions–were found to be very strongly related, but distinguishable by virtue of their different patterns of correlations with other variables, including GRE General Test scores. Examinee self‐reports of both worry and emotionality were moderately related to test performance on each section of the GRE General Test, with higher anxiety associated with lower test performance. (These relationships were essentially identical for each ethnic or racial group considered.) Worry was more strongly related than emotionality to test performance, and, when they were considered together, only worry remained highly related to test performance. Although the relationship is clear, these results do not establish a direction of causality, i.e., whether anxiety impairs test performance, whether poor test performance increases anxiety, or whether both test anxiety and test performance are affected by some other factors. Nor do the results establish the levels at which test anxiety may facilitate rather than debilitate test taking.

Examinees' knowledge of certain aspects of GRE test taking (e.g., how to cancel test scores) and their perceptions of graduate schools (e.g., their reliance on GRE scores in admission decisions) showed slight correlations with test anxiety. Examinees also perceived a number of other factors as contributing to test anxiety. These included, for example, the pressures of a timed test and the attitudes of test administrators. The conclusion was reached that test anxiety is both prevalent enough and severe enough among GRE test takers to warrant the continuing attention of the GRE Program. A number of suggestions were made for further research, which would involve determining whether or not some of the correlates of test anxiety that were identified may also be causes.
RETENTION OF BLACK AND HISPANIC DOCTORAL STUDENTS
Authors: Clewell Beatriz Chu
Published: September 2014

This study tested the feasibility of determining whether factors influencing persistence and nonpersistence of minority doctoral students can be identified,‐whether potentially successful minority doctoral students can be identified at the graduate entry level, and whether institutional practices that encourage or deter minority participation in graduate education can be determined. For Part I of the study, 63 persisting and nonpersisting doctoral students were interviewed regarding their experiences in graduate school; information about their personal and background characteristics was also collected. Identifying and locating an adequate number Of nonpersisters (in order to make any meaningful comparisons) proved not to be feasible. The study was able to describe characteristics and experiences of persisters. Persisters in the study came from low socioeconomic backgrounds; showed a high degree of achievement in high school; had supportive major advisers; participated in professional activities while in graduate school; pursued the Ph.D. because of a desire for knowledge; and, in spite of wanting to leave the programs, completed the doctorate because they did not wish to experience failure.

For Part II of the study, 52 faculty and staff at six graduate institutions were interviewed to determine their policies and practices regarding minority doctoral students. It was found that the level of support for minority students varied greatly among institutions. Policies and practices that appear to encourage participation of minority students include an institution‐wide policy regarding minority graduate students, coordination of services for minority students by an entity above the departmental level, early identification of minority applicants, special admissions arrangements, support services focused on minority students' needs, and efficient record keeping to monitor effectiveness of efforts.
THE PREDICTIVE VALIDITY OF THE RESTRUCTURED GRE WITH PARTICULAR ATTENTION TO OLDER STUDENTS
Authors: Swinton Spencer S.
Published: September 2014

Data from 99 graduate departments that had participated in the Graduate Record Examinations (GRE) Validity Study Service from 1983 through 1985 were analysed with an empirical Bayes regression model that allows each department's mean scores to influence that department's regression coefficients. To be included in the analysis, students had to have taken the GRE General Test on or after October 1981, when the analytical measure was revised.

The empirical Bayes procedure yielded validities at least as high as are commonly reported for least squares analyses. More importantly, it yielded meaningful residuals from a single general model fit to all departments. These comparable residuals made it possible to examine deviations for relatively small subgroups, such as male or female humanities students aged 25 and over.

The major finding was a significant underprediction of first‐year grade average for older females in all graduate fields. Although it had been predicted that they would do less well than younger students and about as well as males, they in fact earned considerably higher grades than all other groups.

It is suggested that graduate admissions committees broaden efforts to identify nontraditional evidence of talent, motivation, and accomplishment in applicants from this group. The GRE data analysis shows that if a larger proportion of returning females were recruited and admitted, they would perform as well or better than currently enrolled younger students.
A NEW LOOK AT FORMULATING HYPOTHESES ITEMS
Authors: Carlson Sybil B. , Ward William C.
Published: September 2014

In the past, the GRE Board supported research on an item type that measures higher‐level cognitive abilities and that uses a free‐response format–the Formulating Hypotheses (FH) item type. Further research was not recommended because of issues associated with the cost and feasibility of the operational use of a test composed of FH items. This project focused on the two major issues that need to be addressed in considering FH items for operational use: (1) the costs of scoring, and (2) rather than the conventional number‐right scoring, the assignment of scores along a range of values. The first issue was addressed directly by seeking ways to increase the efficiency of scoring through computerized delivery and scoring. The second issue was addressed both directly and indirectly by recommending specific procedures for the computer recognition of responses and problem delivery that will be sufficiently reliable and well‐rationalized to be acceptable to reasonable evaluators.

This project involved collaboration with experts who are closely involved in confronting the issues involved in the computer recognition and evaluation of open‐ended responses. After a series of analyses to explore the design and scoring of FH‐type items for computer delivery, we arrived at specific recommendations for developing a system to deliver computerized problems of the FH type. When developed, the prototype also will serve as a computerized research tool to conduct further investigations of potential variations in these types of items.
THE FOUR GENERATIONS OF COMPUTERIZED EDUCATIONAL MEASUREMENT
Authors: Bunderson C. Victor , Inouye Dillon K. , Olsen James B.
Published: September 2014

Educational measurement is undergoing a revolution, due to the rapid dissemination of information‐processing technology. One of the most notable aspects of that revolution is the rapidity with which it has come upon us. It is perhaps inevitable that the recent growth in power and sophistication of computing resources and the widespread dissemination of computers in daily life have brought about irreversible changes in educational measurement.

Recent developments in computerized measurement are summarized by placing them in a four‐generation framework, in which each generation represents a genus of increasing sophistication and power.

Generation 1. Computerized testing (CT): administering conventional tests by computer

Generation 2. Computerized adaptive testing (CAT): tailoring the difficulty or contents of the next piece presented or an aspect of the timing of the next item on the basis of examinees' responses

Generation 3. Continuous measurement (CM): using calibrated measures embedded in a curriculum to continuously and unobtrusively estimate dynamic changes in the student's achievement trajectory and profile as a learner

Generation 4. Intelligent measurement (IM): producing intelligent scoring, interpretation of individual profiles, and advice to learners and teachers, by means of knowledge bases and inferencing procedures

While acknowledging the obvious pitfalls associated with proposing a framework in a developing field, the authors hope that the suggested framework will provide an ad interim contribution to the field's universe of discourse and facilitate communication about the rapidly developing issues.
ASSESSING LEADERSHIP POTENTIAL AT THE NAVAL ACADEMY WITH A BIOGRAPHICAL MEASURE
Authors: Stricker Lawrence J.
Published: September 2014

The aim of this study was to construct and validate a biographical inventory to measure personality traits that are predictive of leadership. The experimental inventory, consisting of tentative scales for Dominance, Emotional Stability, Need for Achievement, Self‐Confidence, and Sociability, was administered to incoming midshipmen at the Naval Academy. The tentative scales were item analyzed, and the validity of the final scales was appraised against subsequent peer ratings of the traits and of leadership, as well as against first‐semester grades that may also reflect leadership (Military Performance and Professional Military Quality Point Rating). The Sociability, Dominance, and Need for Achievement scales demonstrated convergent and discriminant validity, and correlated with the leadership criteria; the Emotional Stability and Self‐Confidence scales showed no signs of validity. Although the level of validity was often modest, the Sociability scale correlated appreciably (.28) with the peer rating of leadership, suggesting that this measure may have practical value in assessing leadership potential.
EXAMINING THE RELATIONSHIP BETWEEN DIFFERENTIAL ITEM FUNCTIONING AND ITEM DIFFICULTY
Authors: Kulick Edward , Hu P. Gillian
Published: September 2014

This study examined the relationship of differential item functioning (DIF) to item difficulty on the Scholastic Aptitude Test (SAT). The data comprise verbal and mathematical item statistics from nine recent administrations of the SAT. In general, item difficulty is related to DIF. The nature of that relationship appears to be independent of the choice of DIF index (either the Mantel‐Haenszel or the standardization approach) as well as of test form. However, the relationship was dependent on the particular group comparison and on both the test sections and the item type being analyzed.

The relationship was strong for each of the racial and ethnic group contrasts—in which black, Hispanic, and Asian American examinees were compared in turn with white examinees—but was weak for the female and male examinee contrast. The relationship also appeared stronger on the verbal sections than on the mathematical sections. The relationship is such that more difficult items tended to exhibit positive DIF (DIF favored the focal group over the white reference group). On the verbal sections, only the reading comprehension item type (with the smallest observed range in item difficulty) failed to exhibit a strong relationship.

Another index, the standardized difference in percentage omit (DIFPOM), correlated very highly (negatively) with DIF. Differential omission refers to a relative difference in omit rates between groups matched in ability. In fact, DIFPOM was consistently a better predictor of DIF in most models than was item difficulty. The relationship between DIF and DIFPOM held up across all four comparisons, including gender. It was also present in the mathematical sections with nearly the same magnitude exhibited in the verbal sections.

Although DIF and DIFPOM are mathematically dependent measures, it was proposed that DIFPOM may be partly responsible for the relationship between DIF and item difficulty. To what extent DIF is a consequence of differential omission and to what extent differential omission is a manifestation of DIF is problematic. Nonetheless, the presence of differential omission on a test has the potential to influence DIF indices and therefore should be an important concern especially for formula‐scored tests, where omission occurs often on difficult items.

Among other findings is that Hispanic and black focal groups tended to omit differentially less than did the white reference groups. For Asian American examinees, the reverse holds. For females and males, the direction depends on the test sections. In general, groups that omitted differentially less experienced a relative advantage (high‐positive DIF values) on the more difficult items, as measured by the DIF indices studied here (which treat omits as wrong in their calculation).
Development of HPLC with Photo‐diode Array Method for the Determination of Ramipril in Tablets Using Factorial Design
Authors: Wu Yu‐Tse , Cham Thau‐Ming , Tsai Tong‐Rong
Published: September 2014

This study was to develop a liquid chromatographic method for the analysis of ramipril by the design of experiment. We first examined the effects of chromatographic parameters, such as column temperature, pH of mobile phase, flow rate of mobile phase and ion‐pairing reagents, on the isomerization of ramipril, and useda 23 factorial design to optimize the chromatographic conditions. This optimized method demonstrated good system suitability and linearity within 1.0–50 µg mL−1 (r2>0.999). The intra‐day and inter‐day precisions ranged from 0.4 to 2.7 %, and accuracy ranged from 98 to 100 %. The recoveries were greater than 99.2 %. The robustness test revealed the method remained unaffected by small deliberate variations of method parameters. This method was applied for the determination of ramipril in tablets. This study demonstrated that design of experiment was useful to efficiently assess the impacts of different parameters for analytical method development and optimization.
Online Detection of Ropivacaine in Drip Bags Using Polypyrrole/graphene Oxide Materials
Authors: Wu Ren‐Jang , Chen Mei‐Yun , Hsien Bing‐Huan , Luk Hsiang‐Ning , Chavali Murthy
Published: September 2014

A novel method of measuring the concentration of the local anesthetic ropivacaine drip bags used in hospi‐ tals was developed using electrochemical impedance technique. Polypyrrole (Ppy)/graphene oxide (GO) composites were prepared by electrochemically polymerization over Au electrodes, which served as working electrodes. The Ppy/GO composite electrodes were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Various concentrations of ropivacaine (0.1–20 ppm) were prepared in a sample drip bag solution of 0.9 % NaCl from hostpital. The composite Ppy/1 % GO electrode exhibited strongest linearity (R2=0.960) than the Ppy electrode (R2=0.928) at a frequency of 100 kHz. The detection limits of ropivacaine on Ppy and Ppy/1 % GO were calculated as 0.11 ppm and 0.08 ppm, respectively. The proposed system yielded response and recovery times under 1 sec detecting 0.1 ppm (100 g/L) of ropivacaine; thus, the proposed online method is promising for measuring ropivacaine concentrations in drip bags. Molecular simulations and equivalent circuits were applied to explain the dynamic behavior of ropivacaine detection system using Ppy and Ppy/GO materials.
An Environmentally Friendly Method for N‐Methylation of 5‐Substituted 1H‐Tetrazoles with a Green Methylating Reagent: Dimethyl Carbonate
Authors: Xie Aming , Zhang Qiang , Liu Yangyang , Feng Liandong , Hu Xinyu , Dong Wei
Published: September 2014

An environmentally friendly method was established for the N‐methylation of the 5‐substituted 1H‐tetrazoles with a green reagent: DMC. DABCO was the optimal catalyst, and hazardous chemicals were avoided in this protocol. A plausible catalytic mechanism is proposed, which consists of a DABCO‐activated process and a thermally induced rearrangement of tetrazole carbamates.
Live fences – a hidden resource of soil fertility in West Kenya
Authors: Theobald Tim F. H. , Mussgnug Frank , Becker Mathias
Published: September 2014

In the highlands of Western Kenya, intensified land use combined with low use of mineral fertilizers at farm level is driving soil nutrient depletion and declining yield levels. All farms and individual field crop plots are surrounded by life fences and the area under such hedge structure is estimated to cover 3–5% of the total farmland area. The land below the hedges is not tilled and may receive nutrient and carbon inputs by the occasional addition of field crop residues and litter fall. We hypothesized that the areas covered by live fences represent not only an important land resource, but are also largely untapped sites characterized by high soil fertility in an otherwise largely degraded environment. We characterized physico‐chemical attributes of top soils collected on farmland and from adjacent live fences composed of five different fencing species in representative environments of Kakamega district (sandy Acrisol and bimodal rainfall distribution vs. clay Ferralsol and monomodal rainfall distribution). In addition, the maize production potential of these soils was assessed in a supplementary pot experiment. Concentrations and total amounts of soil C, N, N supplying capacity, exchangeable K, as well as aggregate stability tended to be higher in hedge structures than in field crop soil. The amount of labile (permanganate‐oxidizable) carbon and the carbon management index in fence lines on Acrisol were similar to those of the adjacent Kakamega rain forest reserve, while they were reduced by > 50% in crop fields. These trends were reflected in the biomass and N and K uptake by maize in potted soil. Effects were generally larger in Acrisol than in Ferralsol and were most pronounced with Tithonia diversifolia. We conclude that live fences are soil fertility hotspots that may be valorised in the future by replacing the generally unproductive fencing species with economical perennial crops.
Acousto‐optic mode coupling excited by superimposed flexural waves in a solid‐core microstructured optical fiber with hexagonal air‐hole array cladding
Authors: Qiu Minghui , Zhang Hao , Kang Shouxin , Miao Yinping , Liu Bo
Published: September 2014

The acousto‐optic mode coupling characteristics of a solid‐core microstructured optical fiber excited by superimposed flexural acoustic waves have been investigated by using two acoustic transducers with similar physical settings in a serial configuration. Theoretical derivation of the superimposed flexural acoustic wave amplitude from a wave equation basis indicates that the acoustically induced refractive index modulation for the unbalanced flexural wave modulation case is strengthened compared to its counterpart when only one flexural wave with relatively weaker amplitude is applied, which is in accordance with our experimental observation of the transmission spectra for different acoustic frequencies. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2831–2836, 2014
A dual‐band subharmonic drain mixer based on single local oscillator
Authors: Oh TaeckKeun , Min Byung‐Wook , Lee Yongshik
Published: September 2014

A dual‐band subharmonic mixer is demonstrated that is capable of down‐converting RF signals in two different bands using second and third harmonic components of the local oscillator (LO) signal. As the mixer requires only one LO, a simple and cost‐effective structure is achieved. The drain bias (VDS) is switched to maximize the gain in each RF band. For demonstration purposes, a dual‐band mixer is designed for RF signals at 2.41 and 3.61 GHz with single LO frequency at 1.2 GHz. The measured results show maximum conversion gains of −6.4 and −7.1 dB at 2.41 and 3.61 GHz, respectively. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2848–2851, 2014
Optical multimedia access transmission and channel bandwidth reduction using compressive sensing technique
Authors: Kwon YoungJae , Ahn Chiteuk , Won Yong‐Yuk
Published: September 2014

A new optical multimedia access transmission using compressive sensing (CS) technique is proposed. The CS can allow us to save the channel bandwidth of optical wired and wireless network because various transmitted data are compressed using it. A 256 × 256 grayscale image with compression ratio of 20%, which is sampled by 10 Gs/s, was transmitted to an optical receiver through 20‐km optical transmission and then was reconstructed successfully using L1 minimization. This means that the CS technique can be an effective candidate for solving the explosive data traffic in the optical wired and wireless access network. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2828–2831, 2014
Accurate broadband multiport reflectometer
Authors: Staszek Kamil , Gruszczynski Slawomir , Wincza Krzysztof
Published: September 2014

ABSTRACT

A novel broadband multiport reflectometer, consisting of a standard 4 × 4 Butler matrix and an additional directional coupler is proposed. It is shown that such a reflectometer provides highly uniform tunable measurement conditions allowing for measurement precision enhancement. The impact of the applied directional coupler's imperfections on the measurement conditions has been theoretically analyzed. The high measurement accuracy of the proposed reflectometer has been proved experimentally by reflection coefficient measurements over the frequency range of 1–5 GHz, which show a good agreement with the results obtained using VNA. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2884–2887, 2014
Cascaded triplet filter using mixed electric and magnetic coupling structure with wide stopband performance
Authors: Chen Fu‐Chang , Hu Hao‐Tao‐ , Qiu Jie‐Ming , Chu Qing‐Xin
Published: September 2014

This article proposes a novel type of microstrip cascaded triplet filter with controllable electric and magnetic coupling. The electric coupling can be tuned by adjusting the gap between the resonators, while the magnetic coupling is dominated by the diameter of the via‐hole. A transmission zero on the upper stopband is produced by the inductive cross‐coupling. To further improve the selectivity of the filter, the source‐load coupling is also proposed to introduce two tunable transmission zeros. To expand the stopband, proper feeding position is selected to suppress the third and fifth harmonics. Based on the proposed structure, a third‐order filter are designed and fabricated. Good agreement between the measured and simulated data is obtained. Measured results indicate that a rejection level of 20 dB up to more than six times the passband frequency can be obtained. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2937–2940, 2014
Design of new multipass gas cells with circular and elliptical cross‐section
Authors: Yan Chunsheng , Wang Binhao , Somesfalean Gabriel
Published: September 2014

Two new types of multipass gas cells with circular and elliptical cross‐sections were developed. As for a cylindrical cell, the reflected rays in the circle would be an irregular trace without superposition and termination, if its central angle is a bit more than 2π/3 for an example. Each two adjacent reflected points have the same optical path difference and optical light passes through different optical distances before different reflection points. As for a cylindroidal cell, if the optical ray passes through one focus point of the ellipse, it must also pass through the other. The light will exit finally from the termination point of an axis. The optical distance depends on the eccentricity of the ellipse and the size of the emergent window. In this article, the detailed mathematical derivations of the optical multireflection traces for the two structures are presented. The unified formula is developed. It is found that these designs have small volumes and adjustable long optical paths. For example, the optical distances in the two structures are about 625 mm for a circle with 50 mm radius. The performance of the system can be enhanced by coating high total reflection film, increasing the processing and positioning precisions, and using highly collimating laser beam. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:3003–3009, 2014
Contact heat evoked potentials: Normal values and use in small‐fiber neuropathy
Authors: Lagerburg Vera , Bakkers Mayienne , Bouwhuis Anne , Hoeijmakers Janneke G.J. , Smit Arjen M. , Van Den Berg Sofia J.M , Hordijk‐De Boer Ineke , Brouwer‐Van Der Lee Mardien D.G. , Kranendonk Douwe , Reulen Jos P.H. , Faber Catharina G. , Merkies Ingemar S.J.
Published: September 2014

Introduction

Contact heat evoked potentials (CHEPs) may be an objective, non‐invasive diagnostic tool in small‐fiber neuropathy (SFN). This study establishes normal CHEP values and examines their applicability in SFN patients. Methods: Standardized CHEPs were administered at the wrist and ankle. The N2 and P2 latencies and N2–P2 peak–peak amplitude were recorded by electroencephalography. We examined healthy subjects (n = 97), stratified by age and gender, and SFN patients with abnormal intraepidermal nerve fiber density (n = 42). CHEP reproducibility and interobserver values were also investigated. Results: CHEP normative values were determined. There was a 9–16% increase in latency per centimeter of height with increasing age. Amplitudes were higher in women than men, and decreased (17–71%) with aging. Test‐retest reproducibility and interobserver values were >0.61 and >0.96, respectively. CHEPs were abnormal in 73.8% of the patients. Conclusion: In this study we have established normal values, reliability, and clinical applicability of CHEPs in SFN. Muscle Nerve, 2015 Muscle Nerve 51:743–749, 2015
Muscle fiber type disproportion (FTD) in a family with mutations in the LMNA gene
Authors: Ruggiero Lucia , Fiorillo Chiara , Tessa Alessandra , Manganelli Fiore , Iodice Rosa , Dubbioso Raffaele , Vitale Floriana , Storti Eugenia , Soscia Ernesto , Santorelli Filippo , Santoro Lucio
Published: September 2014

Introduction

Mutations in the lamin A/C protein cause laminopathies, a heterogeneous group of disorders that include recessive axonal neuropathy (CMT2B1), Emery‐Dreifuss muscular dystrophy (EDMD), limb‐girdle muscular dystrophy (LGMD), dilated cardiomyopathy with conduction defect, and different forms of lipodystrophy and progeria.

Methods

We provide clinical, histopathological, muscle imaging, and cardiac features of a family with heterozygous mutation in the LMNA gene.

Results

We identified heterozygous mutations (c.80C> T; pT27I) in the LMNA gene in 3 family members who had the LGMD phenotype with onset in their early thirties and cardiac conduction defects or dilated cardiomyopathy. Interestingly, muscle biopsies showed changes consistent with fiber type disproportion (FTD).

Conclusions

Fiber type disproportion has been reported only anecdotally in muscle biopsies of patients with LMNA mutations. Our report further supports this association and suggests inclusion of molecular testing for LMNA in the differential diagnosis of myopathies with FTD due to the risk for life threatening events. Muscle Nerve 51: 604–608, 2015