13 research outputs found

    Improved densification and mechanical properties of spark plasma sintered carbon nanotube reinforced alumina ceramics

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    Dense magnesium oxide (MgO) doped multiwalled carbon nanotube (MWCNT) reinforced alumina (Al2O3) nanocomposites were fabricated using spark plasma sintering (SPS). Sintered nanocomposites possessed refined microstructure due to the presence of uniformly dispersed CNTs and ability of MgO to increase densification rate before onset of abnormal grain growth. Williamson-Hall analyses of XRD patterns indicated that matrix crystallite size (L-C) and lattice micro-strain (epsilon(C)) of the nanocomposites decreased by similar to 40% and >30%, respectively, than those of pure Al2O3 (L-C approximate to 75 nm, epsilon(C) = 1.54 x 10(-3)). Present investigation also depicted the suitability of CNT addition in Al2O3 towards achieving higher density of nanocomposites using low temperature (1300 degrees C) SPS. Addition of CNT (especially, at >= 0.6 vol.%) in highly electrically insulating matrix established an electrical percolating network that helped in local heating of matrix particles during SPS and led to higher densification. The highest changes in indentation fracture toughness at 1 kgf and wear rate at 20N normal load were obtained at only 0.6 vol.% MWCNT loading which were >22% higher and 35% lower, respectively, compared to pure Al2O3. (C) 2015 Elsevier B.V. All rights reserved

    Surgery Clerkship Evaluations Are Insufficient for Clinical Skills Appraisal: The Value of a Medical Student Surgical Objective Structured Clinical Examination

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    Optimal methods for medical student assessment in surgery remain elusive. Faculty- and housestaff-written evaluations constitute the chief means of student assessment in medical education. However, numerous studies show that this approach has poor specificity and a high degree of subjectivity. We hypothesized that an objective structured clinical examination (OSCE) in the surgery clerkship would provide additional data on student performance that would confirm or augment other measures of assessment. We retrospectively reviewed data from OSCEs, National Board of Medical Examiners shelf examinations, oral presentations, and written evaluations for 51 third-year Harvard Medical School students rotating in surgery at Massachusetts General Hospital from 2014 to 2015. We expressed correlations between numeric variables in Pearson coefficients, stratified differences between rater groups by one-way analysis of variance, and compared percentages with 2-sample t-tests. We examined commentary from both OSCE and clinical written evaluations through textual analysis and summarized these results in percentages. OSCE scores and clinical evaluation scores correlated poorly with each other, as well as with shelf examination scores and oral presentation grades. Textual analysis of clinical evaluation comments revealed a heavy emphasis on motivational factors and praise, whereas OSCE written comments focused on cognitive processes, patient management, and methods to improve performance. In this single-center study, an OSCE provided clinical skills data that were not captured elsewhere in the surgery clerkship. Textual analysis of faculty evaluations reflected an emphasis on interpersonal skills, rather than appraisal of clinical acumen. These findings suggest complementary roles of faculty evaluations and OSCEs in medical student assessment

    Facility-Based Delivery during the Ebola Virus Disease Epidemic in Rural Liberia: Analysis from a Cross-Sectional, Population-Based Household Survey

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    Background: The Ebola virus disease (EVD) epidemic has threatened access to basic health services through facility closures, resource diversion, and decreased demand due to community fear and distrust. While modeling studies have attempted to estimate the impact of these disruptions, no studies have yet utilized population-based survey data. Methods and Findings: We conducted a two-stage, cluster-sample household survey in Rivercess County, Liberia, in March–April 2015, which included a maternal and reproductive health module. We constructed a retrospective cohort of births beginning 4 y before the first day of survey administration (beginning March 24, 2011). We then fit logistic regression models to estimate associations between our primary outcome, facility-based delivery (FBD), and time period, defined as the pre-EVD period (March 24, 2011–June 14, 2014) or EVD period (June 15, 2014–April 13, 2015). We fit both univariable and multivariable models, adjusted for known predictors of facility delivery, accounting for clustering using linearized standard errors. To strengthen causal inference, we also conducted stratified analyses to assess changes in FBD by whether respondents believed that health facility attendance was an EVD risk factor. A total of 1,298 women from 941 households completed the survey. Median age at the time of survey was 29 y, and over 80% had a primary education or less. There were 686 births reported in the pre-EVD period and 212 in the EVD period. The unadjusted odds ratio of facility-based delivery in the EVD period was 0.66 (95% confidence interval [CI] 0.48–0.90, p-value = 0.010). Adjustment for potential confounders did not change the observed association, either in the principal model (adjusted odds ratio [AOR] = 0.70, 95%CI 0.50–0.98, p = 0.037) or a fully adjusted model (AOR = 0.69, 95%CI 0.50–0.97, p = 0.033). The association was robust in sensitivity analyses. The reduction in FBD during the EVD period was observed among those reporting a belief that health facilities are or may be a source of Ebola transmission (AOR = 0.59, 95%CI 0.36–0.97, p = 0.038), but not those without such a belief (AOR = 0.90, 95%CI 0.59–1.37, p = 0.612). Limitations include the possibility of FBD secular trends coincident with the EVD period, recall errors, and social desirability bias. Conclusions: We detected a 30% decreased odds of FBD after the start of EVD in a rural Liberian county with relatively few cases. Because health facilities never closed in Rivercess County, this estimate may under-approximate the effect seen in the most heavily affected areas. These are the first population-based survey data to show collateral disruptions to facility-based delivery caused by the West African EVD epidemic, and they reinforce the need to consider the full spectrum of implications caused by public health emergencies

    Post Kala-Azar Dermal Leishmaniasis following Treatment with 20 mg/kg Liposomal Amphotericin B (Ambisome) for Primary Visceral Leishmaniasis in Bihar, India

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    The skin disorder Post Kala-Azar Dermal Leishmaniasis (PKDL) occurs in up to 10% of patients treated for visceral leishmaniasis (VL) in India. The pathogenesis of PKDL is not yet fully understood. Cases have been reported in India following therapy with most available treatments, but rarely in those treated with liposomal amphotericin B (Ambisome). Between July 2007 and August 2012 with the support of the Rajendra Memorial Research Institute (RMRI), Médecins Sans Frontières (MSF) supported a VL treatment programme in Bihar, India-an area highly endemic for Leishmania donovani-in which 8749 patients received 20 mg/kg intravenous Ambisome as first-line treatment. This study describes the characteristics of patients who returned to the MSF supported treatment programme with PKDL
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