6,895 research outputs found

    Urine metabolomic analysis to detect metabolites associated with the development of contrast induced nephropathy.

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    ObjectiveContrast induced nephropathy (CIN) is a result of injury to the proximal tubules. The incidence of CIN is around 11% for imaging done in the acute care setting. We aim to analyze the metabolic patterns in the urine, before and after dosing with intravenous contrast for computed tomography (CT) imaging of the chest, to determine if metabolomic changes exist in patients who develop CIN.MethodsA convenience sample of high risk patients undergoing a chest CT with intravenous contrast were eligible for enrollment. Urine samples were collected prior to imaging and 4 to 6 hours post imaging. Samples underwent gas chromatography/mass spectrometry profiling. Peak metabolite values were measured and data was log transformed. Significance analysis of microarrays and partial least squares was used to determine the most significant metabolites prior to CT imaging and within subject. Analysis of variance was used to rank metabolites associated with temporal change and CIN. CIN was defined as an increase in serum creatinine level of ≥ 0.5 mg/dL or ≥ 25% above baseline within 48 hours after contrast administration.ResultsWe sampled paired urine samples from 63 subjects. The incidence of CIN was 6/63 (9.5%). Patients without CIN had elevated urinary citric acid and taurine concentrations in the pre-CT urine. Xylulose increased in the post CT sample in patients who developed CIN.ConclusionDifferences in metabolomics patterns in patients who do and do not develop CIN exist. Metabolites may be potential early identifiers of CIN and identify patients at high-risk for developing this condition prior to imaging

    Stochastic Model for Modulus of Elasticity of Lumber

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    A model was developed for generating the lengthwise variability in modulus of elasticity (MOE) of lumber. A limited grade selection of southern pine visual and machine stress-rated (MSR) grades formed the basic data base, A second-order Markov model was used to generate serially correlated MOE's along 30-inch segments for a piece of lumber. Modulus of elasticity indexes were obtained by dividing each correlated MOE by the average MOE of the piece of lumber. The MOE of each segment was obtained by multiplying the MOE indexes by a single random observation from a distribution of MOE. The distribution characteristics of the generated MOE values are preserved, and the first- and second-order lengthwise serial correlations are preserved

    Shoot growth of woody trees and shrubs is predicted by maximum plant height and associated traits

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    1. The rate of elongation and thickening of individual branches (shoots) varies across plant species. This variation is important for the outcome of competition and other plant-plant interactions. Here we compared rates of shoot growth across 44 species from tropical, warm temperate, and cool temperate forests of eastern Australia.2. Shoot growth rate was found to correlate with a suite of traits including the potential height of the species, xylem-specific conductivity, leaf size, leaf area per xylem cross-section, twig diameter (at 40 cm length), wood density and modulus of elasticity.3. Within this suite of traits, maximum plant height was the clearest correlate of growth rates, explaining 50 to 67% of the variation in growth overall (p p 4. Growth rates were not strongly correlated with leaf nitrogen or leaf mass per unit leaf area.5. Correlations between growth and maximum height arose both across latitude (47%, p p p p < 0.0001), reflecting intrinsic differences across species and sites

    The Design and Validation of the Quantum Mechanics Conceptual Survey

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    The Quantum Mechanics Conceptual Survey (QMCS) is a 12-question survey of students' conceptual understanding of quantum mechanics. It is intended to be used to measure the relative effectiveness of different instructional methods in modern physics courses. In this paper we describe the design and validation of the survey, a process that included observations of students, a review of previous literature and textbooks and syllabi, faculty and student interviews, and statistical analysis. We also discuss issues in the development of specific questions, which may be useful both for instructors who wish to use the QMCS in their classes and for researchers who wish to conduct further research of student understanding of quantum mechanics. The QMCS has been most thoroughly tested in, and is most appropriate for assessment of (as a posttest only), sophomore-level modern physics courses. We also describe testing with students in junior quantum courses and graduate quantum courses, from which we conclude that the QMCS may be appropriate for assessing junior quantum courses, but is not appropriate for assessing graduate courses. One surprising result of our faculty interviews is a lack of faculty consensus on what topics should be taught in modern physics, which has made designing a test that is valued by a majority of physics faculty more difficult than expected.Comment: Submitted to Physical Review Special Topics: Physics Education Researc

    The development and preliminary validation of the Challenge and Threat in Sport (CAT-Sport) Scale

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    This paper outlines the development and preliminary validation of a sport-specific measure of athletes’ experience of challenge and threat. Three independent studies assess the content validity, factor structure, criterion validity and internal consistency of the Challenge and Threat in Sport (CAT-Sport) Scale. In study 1, a group of 25 athletes and two experts assessed the content validity of items derived from existing measures of challenge and threat. Participants examined a pool of 25 items, and were asked to rate the items’ applicability to their experiences of challenge and threat in sport. Items failing to reach applicability of 50% were excluded from further analysis. In study 2, 197 runners completed the 21 items retained from study 1 before competition. A principal components analysis with an oblique, direct oblimin rotation yielded a 12-item, two component solution with items indicative of athletes’ experiences of challenge and threat. In study 3, 201 shooters completed the 12-item CAT-Sport before competition. Confirmatory factor analysis indicated that a 12-item 2-factor correlated model provided acceptable model fit with good internal consistency and criterion validity. Collectively these studies provide support for the CAT-Sport as a measure of athletes’ experience of challenge and threat in anticipation of sport competition

    Independent evaluation of a simple clinical prediction rule to identify right ventricular dysfunction in patients with shortness of breath

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    BACKGROUND: Many patients have unexplained persistent dyspnea after negative computed tomographic pulmonary angiography (CTPA). We hypothesized that many of these patients have isolated right ventricular (RV) dysfunction from treatable causes. We previously derived a clinical decision rule (CDR) for predicting RV dysfunction consisting of persistent dyspnea and normal CTPA, finding that 53% of CDR-positive patients had isolated RV dysfunction. Our goal is to validate this previously derived CDR by measuring the prevalence of RV dysfunction and outcomes in dyspneic emergency department patients. METHODS: A secondary analysis of a prospective observational multicenter study that enrolled patients presenting with suspected PE was performed. We included patients with persistent dyspnea, a nonsignificant CTPA, and formal echo performed. Right ventricular dysfunction was defined as RV hypokinesis and/or dilation with or without moderate to severe tricuspid regurgitation. RESULTS: A total of 7940 patients were enrolled. Two thousand six hundred sixteen patients were analyzed after excluding patients without persistent dyspnea and those with a significant finding on CTPA. One hundred ninety eight patients had echocardiography performed as standard care. Of those, 19% (95% confidence interval [CI], 14%-25%) and 33% (95% CI, 25%-42%) exhibited RV dysfunction and isolated RV dysfunction, respectively. Patients with isolated RV dysfunction or overload were more likely than those without RV dysfunction to have a return visit to the emergency department within 45 days for the same complaint (39% vs 18%; 95% CI of the difference, 4%-38%). CONCLUSION: This simple clinical prediction rule predicted a 33% prevalence of isolated RV dysfunction or overload. Patients with isolated RV dysfunction had higher recidivism rates and a trend toward worse outcomes

    Medical student use of communication elements and association with patient satisfaction: a prospective observational pilot study

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    BACKGROUND: Effective communication with patients impacts clinical outcome and patient satisfaction. We measure the rate at which medical students use six targeted communication elements with patients and association of element use with patient satisfaction. METHODS: Participants included fourth year medical students enrolled in an emergency medicine clerkship. A trained observer measured use of six communication elements: acknowledging the patient by name, introducing themselves by name, identifying their role, explaining the care plan, explaining that multiple providers would see the patient, and providing an estimated duration of time in the emergency department. The observer then conducted a survey of patient satisfaction with the medical student encounter. RESULTS: A total of 246 encounters were documented among forty medical student participants. For the six communication elements evaluated, in 61% of encounters medical students acknowledged the patient, in 91% they introduced themselves, in 58 % they identified their role as a student, in 64% they explained the care plan, in 80% they explained that another provider would see the patient, and in only 6% they provided an estimated duration of care. Only 1 encounter (0.4%) contained all six elements. Patients' likelihood to refer a loved one to that ED was increased when students acknowledged the patient and described that other providers would be involved in patient care (P = 0.016 and 0.015 respectively, Chi Square). Likewise, patients' likelihood to return to the ED was increased when students described their role in patient care (P = 0.035, Chi Square). CONCLUSIONS: This pilot study demonstrates that medical students infrequently use all targeted communication elements. When they did use certain elements, patient satisfaction increased. These data imply potential benefit to additional training for students in patient communication
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