Aligning physical elements with persons' attitude: an approach using Rasch measurement theory

Affective engineering uses mathematical models to convert the information obtained from persons' attitude to physical elements into an ergonomic design. However, applications in the domain have not in many cases met measurement assumptions. This paper proposes a novel approach based on Rasch measurement theory to overcome the problem. The research demonstrates that if data fit the model, further variables can be added to a scale. An empirical study was designed to determine the range of compliance where consumers could obtain an impression of a moisturizer cream when touching some product containers. Persons, variables and stimulus objects were parameterised independently on a linear continuum. The results showed that a calibrated scale preserves comparability although incorporating further variables

Using item response theory to explore the psychometric properties of extended matching questions examination in undergraduate medical education

BACKGROUND: As assessment has been shown to direct learning, it is critical that the examinations developed to test clinical competence in medical undergraduates are valid and reliable. The use of extended matching questions (EMQ) has been advocated to overcome some of the criticisms of using multiple-choice questions to test factual and applied knowledge. METHODS: We analysed the results from the Extended Matching Questions Examination taken by 4th year undergraduate medical students in the academic year 2001 to 2002. Rasch analysis was used to examine whether the set of questions used in the examination mapped on to a unidimensional scale, the degree of difficulty of questions within and between the various medical and surgical specialties and the pattern of responses within individual questions to assess the impact of the distractor options. RESULTS: Analysis of a subset of items and of the full examination demonstrated internal construct validity and the absence of bias on the majority of questions. Three main patterns of response selection were identified. CONCLUSION: Modern psychometric methods based upon the work of Rasch provide a useful approach to the calibration and analysis of EMQ undergraduate medical assessments. The approach allows for a formal test of the unidimensionality of the questions and thus the validity of the summed score. Given the metric calibration which follows fit to the model, it also allows for the establishment of items banks to facilitate continuity and equity in exam standards

Identification and characterization of a galacturonic acid transporter from Neurospora crassa and its application for Saccharomyces cerevisiae fermentation processes

BACKGROUND: Pectin-rich agricultural wastes potentially represent favorable feedstocks for the sustainable production of alternative energy and bio-products. Their efficient utilization requires the conversion of all major constituent sugars. The current inability of the popular fermentation host Saccharomyces cerevisiae to metabolize the major pectic monosaccharide D-galacturonic acid (D-GalA) significantly hampers these efforts. While it has been reasoned that the optimization of cellular D-GalA uptake will be critical for the engineering of D-GalA utilization in yeast, no dedicated eukaryotic transport protein has been biochemically described. Here we report for the first time such a eukaryotic D-GalA transporter and characterize its functionality in S. cerevisiae. RESULTS: We identified and characterized the D-GalA transporter GAT-1 out of a group of candidate genes obtained from co-expression analysis in N. crassa. The N. crassa Δgat-1 deletion strain is substantially affected in growth on pectic substrates, unable to take up D-GalA, and impaired in D-GalA-mediated signaling events. Moreover, expression of a gat-1 construct in yeast conferred the ability for strong high-affinity D-GalA accumulation rates, providing evidence for GAT-1 being a bona fide D-GalA transport protein. By recombinantly co-expressing D-galacturonate reductase or uronate dehydrogenase in yeast we furthermore demonstrated a transporter-dependent conversion of D-GalA towards more reduced (L-galactonate) or oxidized (meso-galactaric acid) downstream products, respectively, over a broad concentration range. CONCLUSIONS: By utilizing the novel D-GalA transporter GAT-1 in S. cerevisiae we successfully generated a transporter-dependent uptake and catalysis system for D-GalA into two products with high potential for utilization as platform chemicals. Our data thereby provide a considerable first step towards a more complete utilization of biomass for biofuel and value-added chemicals production

Magnetic phase transition in V2O3 nanocrystals

V2O3 nanocrystals can be synthesized through hydrothermal reduction of VO(OH)2 using hydrazine as a reducing agent. Addition of different ligands to the reaction produces nanoparticles, nanorods and nanoplatelets of different sizes. Small nanoparticles synthesized in this manner show suppression of the magnetic phase transition to lower temperatures. Using muon spin relaxation spectroscopy and synchrotron x-ray diffraction, it is determined that the volume fraction of the high-temperature phase, characterized by a rhombohedral structure and paramagnetism, gradually declines with decreasing temperature, in contrast to the sharp transition observed in bulk V2O3.Comment: 6 pages, 6 figure

Aggregation of full length immunoglobulin light chains from AL amyloidosis patients is remodeled by epigallocatechin-3-gallate

Intervention into amyloid deposition with anti-amyloid agents like the polyphenol Epigallocatechin-3-gallate (EGCG) is emerging as an experimental secondary treatment strategy in systemic light chain amyloidosis (AL). In both AL and Multiple Myeloma (MM), soluble immunoglobulin light chains (LC) are produced by clonal plasma cells, but only in AL they form amyloid deposits in vivo. We investigated the amyloid formation of patient-derived LC and their susceptibility to EGCG in vitro to probe commonalities and systematic differences in their assembly mechanisms. We isolated nine LC from urine of AL and MM patients. We quantified their thermodynamic stabilities, and monitored their aggregation under physiological conditions by ThT fluorescence, light scattering, SDS-stability and atomic force microscopy. LC from all patients formed amyloid-like aggregates, albeit with individually different kinetics. LC existed as dimers, ~50% of which were linked by disulfide bridges. Our results suggest that cleavage into LC monomers is required for efficient amyloid formation. The kinetics of AL LC displayed a transition point in concentration dependence, which MM LC lacked. The lack of concentration dependence of MM LC aggregation kinetics suggests that conformational change of the light chain is rate-limiting for these proteins. Aggregation kinetics displayed two distinct phases, which corresponded to the formation of oligomers and amyloid fibrils, respectively. EGCG specifically inhibited the second aggregation phase and induced the formation of SDS-stable, non-amyloid LC aggregates. Our data suggest that EGCG intervention does not depend on the individual LC sequence and is similar to the mechanism observed for amyloid-{beta} and {alpha}-synuclein

Reliability and responsiveness of measures of pain in people with osteoarthritis of the knee: a psychometric evaluation

PURPOSE: To examine the fit between data from the Short Form McGill Pain Questionnaire (SF-MPQ-2) and the Rasch model, and to explore the reliability and internal responsiveness of measures of pain in people with knee osteoarthritis. METHODS: Participants with knee osteoarthritis completed the SF-MPQ-2, Intermittent and Constant Osteoarthritis Pain questionnaire (ICOAP) and painDETECT. Participants were sent the same questionnaires 3 and 6 months later. RESULTS: Fit to the Rasch model was not achieved for the SF-MPQ-2 Total scale. The Continuous subscale yielded adequate fit statistics after splitting item 10 on uniform DIF for gender, and removing item 9. The Intermittent subscale fit the Rasch model after rescoring items. The Neuropathic subscale had relatively good fit to the model. Test-retest reliability was satisfactory for most scales using both original and Rasch scoring ranging from fair to substantial. Effect sizes ranged from 0.13 to 1.79 indicating good internal responsiveness for most scales. CONCLUSIONS: These findings support the use of ICOAP subscales as reliable and responsive measure of pain in people with knee osteoarthritis. The MPQ-SF-2 subscales found to be acceptable alternatives. Implications for Rehabilitation The McGill Pain Questionnaire short version 2 is not a unidimensional scale in people with knee osteoarthritis, whereas three of the subscales are unidimensional. The McGill Pain Questionnaire short version 2 Affective subscale does not have good measurement properties for people with knee osteoarthritis. The McGill Pain Questionnaire short version 2 and the Intermittent and Constant Osteoarthritis Pain scales can be used to assess change over time. The painDETECT performs better as a screening measure than as an outcome measure

Author finding post print - The Multiple Sclerosis-Fatigue Self- Efficacy (MS-FSE) scale: initial validation.

To examine the validity and sensitivity to change of the Multiple Sclerosis-Fatigue Self-Efficacy scale