479 research outputs found

    Switched reluctance motor design for electric vehicles based on harmonics and back EMF analysis

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    Permanent magnet synchronous motors are widely accepted in automotive applications. The high torque density, high rotational speed with maximum efficiency in electric vehicle applications is technically challenging for motor design. However, these machines are expensive and difficult to work at high-temperature harsh environment due to permanent magnets demagnetisation features. Alternatively, switched reluctance motors can provide similar output characteristics and a wider speed. Thus these are considered to be more fault tolerant and more reliable. This study proposes a 20 kW, three-phase switched reluctance motor and analyse its overall performance and harmonic contents. The study is conducted by optimising the slot filling factor, excitation voltage and switching sequence of an asymmetrical half bridge converter. A finite element model is used to predict the core and copper losses and other influencing parameters. Simulation results are presented and analysed the effectiveness of the proposed switched reluctance motor (SRM)

    Antibacterial efficacy of indigenous Pakistani honey against extensively drug-resistant clinical isolates of Salmonella enterica serovar Typhi: an alternative option to combat antimicrobial resistance

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    Abstract Background Extensively drug-resistant (XDR) Salmonella enterica serovar Typhi (S. Typhi) poses a grave threat to public health due to increased mortality and morbidity caused by typhoid fever. Honey is a promising antibacterial agent, and we aimed to determine the antibacterial activity of honey against XDR S. Typhi. Methods We isolated 20 clinical isolates of XDR S. Typhi from pediatric septicemic patients and determined the minimum inhibitory concentrations (MICs) of diferent antibiotics against the pathogens using the VITEK 2 Compact system. Antimicrobial-resistant genes carried by the isolates were identifed using PCR. The antibacterial efcacy of fve Pakistani honeys was examined using agar well difusion assay, and their MICs and minimum bactericidal concentrations (MBCs) were determined with the broth microdilution method. Results All 20 isolates were confrmed as S. Typhi. The antibiogram phenotype was confrmed as XDR S. Typhi with resistance to ampicillin (≄32 ”g/mL), ciprofoxacin (≄4 ”g/mL), and ceftriaxone (≄4 ”g/mL) and sensitivity to azithromycin (≀16 ”g/mL) and carbapenems (≀1 ”g/mL). Molecular conformation revealed the presence of blaTM-1, Sul1, qnrS, gyrA, gyrB, and blaCTX-M-15 genes in all isolates. Among the fve honeys, beri honey had the highest zone of inhibition of 7–15 mm and neem honey had a zone of inhibition of 7–12 mm. The MIC and MBC of beri honey against 3/20 (15%) XDR S. Typhi isolates were 3.125 and 6.25%, respectively, while the MIC and MBC of neem were 3.125 and 6.25%, respectively, against 3/20 (15%) isolates and 6.25 and 12.5%, respectively, against 7/20 (35%) isolates. Conclusion Indigenous honeys have an efective role in combating XDR S. Typhi. They are potential candidates for clinical trials as alternative therapeutic options against XDR S. Typhi isolates. Keywords Antimicrobial resistance, Natural antibiotics, XDR S. Typhi, MIC, Honey, Resistance gene

    Cross‐species systems analysis of evolutionary toolkits of neurogenomic response to social challenge

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147855/1/gbb12502.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147855/2/gbb12502-sup-0002-TableS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147855/3/gbb12502_am.pd

    Remaining idle time aware intelligent channel bonding schemes for cognitive radio sensor networks

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    Channel bonding (CB) is a technique used to provide larger bandwidth to users. It has been applied to various networks such as wireless local area networks, wireless sensor networks, cognitive radio networks, and cognitive radio sensor networks (CRSNs). The implementation of CB in CRSNs needs special attention as primary radio (PR) nodes traffic must be protected from any harmful interference by cognitive radio (CR) sensor nodes. On the other hand, CR sensor nodes need to communicate without interruption to meet their data rate requirements and conserve energy. If CR nodes perform frequent channel switching due to PR traffic then it will be difficult to meet their quality of service and data rate requirements. So, CR nodes need to select those channels which are stable. By stable, we mean those channels which having less PR activity or long remaining idle time and cause less harmful interference to PR nodes. In this paper, we propose two approaches remaining idle time aware intelligent channel bonding (RITCB) and remaining idle time aware intelligent channel bonding with interference prevention (RITCB-IP) for cognitive radio sensor networks which select stable channels for CB which have longest remaining idle time. We compare our approaches with four schemes such as primary radio user activity aware channel bonding scheme, sample width algorithm, cognitive radio network over white spaces and AGILE. Simulation results show that our proposed approaches RITCB and RITCB-IP decrease harmful interference and increases the life time of cognitive radio sensor nodes

    Scaling of the F_2 structure function in nuclei and quark distributions at x>1

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    We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for x>1x>1, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.Comment: 5 pages, 4 figures, to be submitted to physical revie

    Automatic Extraction of Nuclei Centroids of Mouse Embryonic Cells from Fluorescence Microscopy Images

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    Accurate identification of cell nuclei and their tracking using three dimensional (3D) microscopic images is a demanding task in many biological studies. Manual identification of nuclei centroids from images is an error-prone task, sometimes impossible to accomplish due to low contrast and the presence of noise. Nonetheless, only a few methods are available for 3D bioimaging applications, which sharply contrast with 2D analysis, where many methods already exist. In addition, most methods essentially adopt segmentation for which a reliable solution is still unknown, especially for 3D bio-images having juxtaposed cells. In this work, we propose a new method that can directly extract nuclei centroids from fluorescence microscopy images. This method involves three steps: (i) Pre-processing, (ii) Local enhancement, and (iii) Centroid extraction. The first step includes two variations: first variation (Variant-1) uses the whole 3D pre-processed image, whereas the second one (Variant-2) modifies the preprocessed image to the candidate regions or the candidate hybrid image for further processing. At the second step, a multiscale cube filtering is employed in order to locally enhance the pre-processed image. Centroid extraction in the third step consists of three stages. In Stage-1, we compute a local characteristic ratio at every voxel and extract local maxima regions as candidate centroids using a ratio threshold. Stage-2 processing removes spurious centroids from Stage-1 results by analyzing shapes of intensity profiles from the enhanced image. An iterative procedure based on the nearest neighborhood principle is then proposed to combine if there are fragmented nuclei. Both qualitative and quantitative analyses on a set of 100 images of 3D mouse embryo are performed. Investigations reveal a promising achievement of the technique presented in terms of average sensitivity and precision (i.e., 88.04% and 91.30% for Variant-1; 86.19% and 95.00% for Variant-2), when compared with an existing method (86.06% and 90.11%), originally developed for analyzing C. elegans images

    The role of sources of social support on depression and quality of life for university students.

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    Prevalence of mental health problems in university students is increasing and attributable to academic, financial and social stressors. Lack of social support is a known determinant of mental health problems. We examined the differential impact of sources of social support on student wellbeing. University students completed an online survey measuring depressive symptoms (Patient Health Questionnaire (PHQ-9)), social support (Multidimensional Perceived Social Support (MPSS)), and quality of life (WHOQOL-BREF). The sample was 461 students (82% female, mean age 20.62 years). The prevalence of depressive symptoms was 33%. Social support from family, and friends was a significant predictor of depressive symptoms (p = 0.000*). Quality of life (psychological) was significantly predicted by social support from family and friends. Quality of life (social relationships) was predicted by social support from significant others and friends. Sources of social support represent a valuable resource for universities in protecting the mental health of students

    Patient attitudes towards medical students at Damascus University teaching hospitals

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    Background: The cooperation of patients and their consent to involve medical students in their care is vital to clinical education, but large numbers of students and lack of experience as well as loss of privacy may evoke negative attitudes of patients, which may sometimes adversely affect the clinical teaching environment. This study aimed to explore the attitudes of patients towards medical students at Damascus University hospitals, and to explore the determinants of those attitudes thus discussing possible implications applicable to clinical teaching. Methods: This cross-sectional study was conducted at three teaching hospitals affiliated to the Faculty of Medicine at Damascus University. Four hundred patients were interviewed between March and April 2011 by a trained sociologist using a structured questionnaire. Results: Of the patients interviewed, 67.8 % approved the presence of medical students during the medical consultation and 58.2 % of them felt comfortable with the presence of students, especially among patients with better socio-economic characteristics. 81.5 % of the patients agreed to be examined by students in the presence of the supervisor, while 40.2 % gave agreement even in the absence of the supervisor. Privacy was the most important factor in the patients ’ reticence towards examination by the students, whilst the relative safety and comfort if a supervisor was available determined patients ’ agreement
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