Separation of incident and reflected waves in wave-current flumes

author's final versionA technique is developed to separate the incident and reflected waves propagating on a known current in a laboratory wave-current flume by analyzing wave records measured at two or more locations using a least squares method. It can be applied to both regular and irregular waves. To examine its performance, numerical tests are made for waves propagating on quiescent or flowing water. In some cases, to represent the signal noise and measurement error, white noise is superimposed on the numerically generated wave signal. For all the cases, good agreement is observed between target and estimation

Does Objective Structured Clinical Examinations Score Reflect the Clinical Reasoning Ability of Medical Students?

Abstract:BackgroundClinical reasoning ability is an important factor in a physician's competence and thus should be taught and tested in medical schools. Medical schools generally use objective structured clinical examinations (OSCE) to measure the clinical competency of medical students. However, it is unknown whether OSCE can also evaluate clinical reasoning ability. In this study, the authors investigated whether OSCE scores reflected students' clinical reasoning abilities.MethodsSixty-five fourth-year medical students participated in this study. Medical students completed the OSCE with 4 cases using standardized patients. For assessment of clinical reasoning, students were asked to list differential diagnoses and the findings that were compatible or not compatible with each diagnosis. The OSCE score (score of patient encounter), diagnostic accuracy score, clinical reasoning score, clinical knowledge score and grade point average (GPA) were obtained for each student, and correlation analysis was performed.ResultsClinical reasoning score was significantly correlated with diagnostic accuracy and GPA (correlation coefficient = 0.258 and 0.380; P = 0.038 and 0.002, respectively) but not with OSCE score or clinical knowledge score (correlation coefficient = 0.137 and 0.242; P = 0.276 and 0.052, respectively). Total OSCE score was not significantly correlated with clinical knowledge test score, clinical reasoning score, diagnostic accuracy score or GPA.ConclusionsOSCE score from patient encounters did not reflect the clinical reasoning abilities of the medical students in this study. The evaluation of medical students' clinical reasoning abilities through OSCE should be strengthened

Ruthenium anchored on carbon nanotube electrocatalyst for hydrogen production with enhanced Faradaic efficiency

Developing efficient and stable electrocatalysts is crucial for the electrochemical production of pure and clean hydrogen. For practical applications, an economical and facile method of producing catalysts for the hydrogen evolution reaction (HER) is essential. Here, we report ruthenium (Ru) nanoparticles uniformly deposited on multi-walled carbon nanotubes (MWCNTs) as an efficient HER catalyst. The catalyst exhibits the small overpotentials of 13 and 17 mV at a current density of 10 mA cm(-2) in 0.5M aq. H2SO4 and 1.0M aq. KOH, respectively, surpassing the commercial Pt/C (16 mV and 33 mV). Moreover, the catalyst has excellent stability in both media, showing almost "zeroloss" during cycling. In a real device, the catalyst produces 15.4% more hydrogen per power consumed, and shows a higher Faradaic efficiency (92.28%) than the benchmark Pt/C (85.97%). Density functional theory calculations suggest that Ru-C bonding is the most plausible active site for the HER

Optimal collimator rotation based on the outline of multiple brain targets in VMAT

Background The aim of this study was to investigate the dosimetric quality in volumetric modulated arc therapy (VMAT) plans with optimal collimator angles that can represent the outline of multiple brain targets. Methods Twenty patients with multiple target volumes in the brain cases were selected retrospectively. To better represent the outline of the multiple brain targets, four conformal arc plans were generated for each patient using one full arc with four collimator settings. The optimal collimator angles calculated from the integrated multi-leaf collimator (MLC) aperture that had the smallest aperture size for certain collimator settings of the conformal arc plan were selected. VMAT plans with the optimal collimator angles with angular sections of 40° and 60° (Colli-VMAT (40°), Colli-VMAT (60°)) were generated, followed by evaluation of field sizes, dose-volumetric parameters and total monitor units (MUs). Results Patient-averaged values of field sizes for Colli-VMAT (40°) (111.5 cm2) were lowest and 1.3 times smaller than those for Std-VMAT (143.6 cm2). Colli-VMAT plans improved sparing of most normal organs but for brain stem and left parotid gland. For the total MUs, the averaged values obtained with the Colli-VMAT (40°) (390 ± 148 MU) were smaller than those obtained with the Std-VMAT (472 ± 235 MU). Conclusions The Colli-VMAT plans with smaller angular sections could be suitable in the clinic for multiple brain targets as well as for irregularly shaped targets. Determination of the optimal collimator rotation generally showed good normal tissue sparing and MU reduction for multiple brain targets.This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2017R1D1A1B03036093) and by a grant from the National R&D Program for Cancer Control, Ministry of Health and Welfare, Republic of Korea (HA16C0025)

Short-term Effects of 308-nm Xenon-chloride Excimer Laser and Narrow-band Ultraviolet B in the Treatment of Vitiligo: A Comparative Study

We compared the clinical efficacy of a short-term intervention of 308-nm excimer laser with that of narrow-band UVB (NBUVB) phototherapy for vitiligo patients to see the early response. Twenty-three symmetrically patterned patches of vitiligo on 8 patients were selected. Vitiligo patches on one side of the body were treated 2 times per week for a maximum of 20 treatments with the excimer laser, and NBUVB phototherapy was used on patches on the other side. Improvement (repigmentation) was assessed on a visual scale via serial photographs taken every five treatments and scored as follows: 0, ≤1% improvement; 1, ≤25% improvement; 2, 26-50% improvement; 3, 51-75% improvement; and 4, ≥75% improvement. At five treatments, the excimer laser-treated patches had an average score of 0.26, compared with 0.04 for patches treated with NBUVB phototherapy. A slightly higher repigmentation (p>0.05) in the excimer treated area was thus observed. At 10, 15, or 20 treatments, the differences between the average scores were significant: 0.83, 1.17, and 1.39 for the excimer-treated patches, and 0.17, 0.30, and 0.74 for the NBUVB phototherapy-treated areas (p<0.05). In conclusion, the 308-nm excimer laser appears to be more effective than NBUVB phototherapy, as it produces more rapid and profound repigmentation

Case of Small Bowel Perforation due to Enteropathy-Type T-Cell Lymphoma

Enteropathy-type T-cell lymphoma (ETTL) is a rare disease with a poor prognosis. According to the World Health Organization (WHO) classification, it is a subtype of the peripheral T-cell lymphomas. This disease is associated with gluten-sensitive enteropathy, has a high risk of intestinal perforation and obstruction, and is refractory to chemotherapeutic treatment. We report the case of a 73-year-old woman who was diagnosed with enteropathy-type T-cell lymphoma of the small intestine, which was positive for the markers of cytotoxic T cells, CD3, CD8, and CD56, on immunohistochemical staining after resection of the perforated terminal ileum