Complex morphology of gastrin-releasing G-cells in the antral region of the mouse stomach.

Gastrin-releasing enteroendocrine cells (G-cells) are usually described as flask-shaped cells with a large base and a small apical pole, integrated in the epithelium lining the basal region of the antral invaginations in the stomach. By means of a transgenic mouse line in which the enhanced version of GFP is endogenously expressed under the control of a gastrin promoter, we have analyzed the spatial distribution and morphological features of G-cells. We found that G-cells were not only located at the basal region of the invagination but to a lesser extent also at the upper region.

Experimental and theoretical investigation of the distance dependence of localized surface plasmon coupled Förster resonance energy transfer.

The distance dependence of localized surface plasmon (LSP) coupled Förster resonance energy transfer (FRET) is experimentally and theoretically investigated using a trilayer structure composed of separated monolayers of donor and acceptor quantum dots with an intermediate Au nanoparticle layer. The dependence of the energy transfer efficiency, rate, and characteristic distance, as well as the enhancement of the acceptor emission, on the separations between the three constituent layers is examined. A d(-4) dependence of the energy transfer rate is observed for LSP-coupled FRET between the donor and acceptor planes with the increased energy transfer range described by an enhanced Förster radius.

Wavelength, concentration, and distance dependence of nonradiative energy transfer to a plane of gold nanoparticles.

Nonradiative energy transfer to metal nanoparticles is a technique used for optical-based distance measurements which is often implemented in sensing. Both Förster resonant energy transfer (FRET) and nanometal surface energy transfer (NSET) mechanisms have been proposed for emission quenching in proximity to metal nanoparticles. Here quenching of emission of colloidal quantum dots in proximity to a monolayer of gold nanoparticles is investigated.

Equating of multi-facet tests across administrations.

The purpose of this study is to explore criteria for common element test equating for performance examinations. Using the multi-facet Rasch model, each element of each facet is calibrated or placed in a relative position on a Benchmark or reference scale. Common elements from each facet, included on the examinations being equated, are used to anchor the facet elements to the Benchmark Scale.

Surface plasmon enhanced energy transfer between donor and acceptor CdTe nanocrystal quantum dot monolayers.

Surface plasmon enhanced Förster resonant energy transfer (FRET) between CdTe nanocrystal quantum dots (QDs) has been observed in a multilayer acceptor QD-gold nanoparticle-donor QD sandwich structure. Compared to a donor-acceptor QD bilayer structure without gold nanoparticles, the FRET rate is enhanced by a factor of 80 and the Förster radius increases by 103%. Furthermore, a strong impact of the donor QD properties on the surface plasmon mediated FRET is reported.

Energy transfer in colloidal CdTe quantum dot nanoclusters.

Quantum dot (QD) nanoclusters were formed using oppositely charged colloidal CdTe QDs, of two different sizes, mixed in aqueous solutions. The photoluminescence (PL) spectra and time-resolved PL decays show signatures of Förster resonant energy transfer (FRET) from the donor QDs to the acceptor QD in the nanoclusters. A concentration dependence of the donor QD lifetime is observed in mixed solutions with a donor: acceptor ratio greater than 1:1.

Reliability of performance examinations: revisited.

This article discusses the reliability for performance examinations with respect to the reproducibility of candidate pass-fail decisions. The multi-facet Rasch model accounts for the difficulty of test forms (examiners + tasks + items) taken by each candidate, so that all candidates are measured against the same criterion. The examiners provide analytic ratings of candidate performance using a defined rating scale.

Relationship between candidate communication ability and oral certification examination scores.

Context: Structured case-based oral examinations are widely used in medical certifying examinations in the USA. These orals assess the candidate's decision-making skills using real or realistic patient cases. Frequently mentioned but not empirically evaluated is the potential bias introduced by the candidate's communication ability.

The impact of receiving the same items on consecutive computer adaptive test administrations.

This study addresses item exposure in a Computerized Adaptive Test (CAT) when the item selection algorithm is permitted to present examinees with questions that they have already been asked in a previous test administration. The results indicate that the combined use of an adaptive algorithm to select items and latent trait theory to estimate person ability provides substantial protection from score contamination. The implications for constraints that prohibit examinees from seeing an item twice are discussed.

Coincident Warthin's tumor and intraparotid dermatopathic lymphadenopathy. Report of a case.

A 52-year-old patient underwent excision of a parotid lump which was fond to consist of a Warthin's tumor coexistent with a lymph node involved in dermatopathic lymphadenopathy. A preoperative fine-needle aspiration specimen contained brown pigment-granule-laden macrophages within the background of many lymphocytes. Failure to correctly diagnose the parotid tumor was likely due to a sampling error.

The Job Responsibilities Scale: invariance in a longitudinal prospective study.

The purpose of the present analysis was to determine the degree of invariance of the Job Responsibilities Scale from 1993 to 1995. Factor analyses were conducted on both year's data and nearly identical factor patterns were found. Rasch rating scale analyses were conducted and nearly identical pairs of item estimates were found.

Postgraduate education: does it improve the knowledge base of practitioners with time?

Purpose: We evaluate the effect of the provision of postgraduate educational material on improving practitioner knowledge base during a 3-year period.

Materials And Methods: A total of 210 urologists were provided 67 monographs in a 2-year period. They were given a pretest before and posttest 1 year after receipt of all monographs.

Interpreting the chi-square statistics reported in the many-faceted Rasch model.

The different chi-square statistics reported in the many-faceted Rasch model analysis are presented and interpreted. In addition, other chi-square summary values are computed and presented for interpretation of facets. The chi-square values are useful for determining: (1) the significance of a facet in the Rasch model; (2) the significant contribution of facet main and interaction effects; (3) differences among facet elements; and (4) identifying the specific facet interaction adjustments to the subjects' calibrated logit ability measure.

Scoring and analysis of performance examinations: a comparison of methods and interpretations.

The purpose of this study was to compare the results and interpretation of the data from a performance examination when four methods of analysis are used. Methods are 1) traditional summary statistics, 2) inter-judge correlations, 3) generalizability theory, and 4) the multi-facet Rasch model. Results indicated that similar sources of variance were identified using each method; however, the multi-facet Rasch model is the only method that linearized the scores and accounts for differences in the particular examination challenged by a candidate before ability estimates are calculated.

Medical technologist career commitment and satisfaction with job benefits.

The purpose of this study was to determine the impact of career commitment on satisfaction with job-related benefits. A validated seven-point career commitment scale was used to measure career commitment. A 31-item benefits survey was used to collect data on satisfaction.

The effect of rater severity on person ability measure: a Rasch model analysis.

This paper presents a method for analyzing oral examinations with an extended, many-faceted Rasch model that calibrates medical specialty candidates, protocols, and raters. Significant variance was found among protocol difficulties and rater severities. When candidates' raw scores were compared with calibrated measures corrected for the bias caused by the particular protocols and raters encountered, variation between candidate scores and measures were observed.

Laboratory staff qualifications and accuracy of proficiency test results. A national study.

In the last quarter of 1988, laboratories from across the country that participated in the College of American Pathologists (Northbrook, Ill) proficiency testing program were asked to complete a questionnaire describing their staffing pattern and submit it with their test results. Laboratories were then divided into two groups, those employing 100% American Society of Clinical Pathologists (Chicago, Ill) certified technologists and those employing 0% American Society of Clinical Pathologists certified technologists. The nonparametric Wilcoxon significance test was used to determine differences in accuracy of test results for laboratories in each group.

Comparability of decisions for computer adaptive and written examinations.

The purpose of this study was to determine the comparability of examinee ability measures, pass/fail decisions, and confidence in the accuracy of pass/fail decisions on written fixed-length and computer adaptive examinations. Medical technology students took two independent tests: a written test of 109 questions and a computer-administered computer adaptive test that included 50 to 100 items tailored to the ability of each student. Results indicated that ability measures on the two tests correlated at 0.

A comparison of intra- and interjudge decision consistencies using analytic and holistic scoring criteria.

This study explored the effect of scoring criteria on the decision consistency of judges. Intra- and interjudge consistencies were compared when two different scoring criteria were used by the same judges. Analytic criteria included detailed assessments of a student's performance, while holistic criteria included only a subjective global assessment.

The first six years' experience with the Pathology Residents' In-Service Examination, 1983-1988.

Data derived from the 1983-1988 administrations of the American Society of Clinical Pathology Residents In-Service Examination (PRISE) are presented. Data indicate an increase in participation by U.S.

The impact of the quality of laboratory staff on the accuracy of laboratory results.

This study tests the premise that laboratories employing medical technologists certified by the Board of Registry of the American Society of Clinical Pathologists (MT[ASCP]) produce more accurate laboratory test results, as measured by the College of American Pathologists proficiency tests. Licensed laboratories in Illinois provided the sample. An accuracy score on the College of American Pathologists proficiency tests was calculated for each laboratory.