16 research outputs found

    magnetization processes in permalloy overlays on magnetic bubble devices.

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    Using colloid techniques domain structure has been studied in several overlay components used in contemporary bubble devices. In isolated elements the demagnetized state is generally simple, containing a small number of domains. The influence of anisotropy on domain structure is demonstrated. Elements initially respond to applied fields by reversible domain boundary movement but in each case it has been found that partial saturation and hysteresis occur once the applied field exceeds a critical value, H(_s). This causes the formation of remanent states with 'magnetization buckling' similar to that found in larger samples of thin-film permalloy. The relationship between and element geometry and thickness and the formation of buckled states by a rotating field were investigated. Such states may adversely affect the operation of a bubble device. The approach to partial saturation in a simple bar has been modelled on the basis of a curved domain wall and approximate values for the saturation field calculated. The external field profile of the bar has also been obtained. Domain structure in various connected chevron columns (bubble detectors) was also studied. In contrast to isolated elements the initial 'zero-field' state in these components is generally one of saturation. This state can be broken by components of applied field parallel or perpendicular to the column and again magnetization buckling is involved. Magnetoresistance changes related to the buckled state were measured and found to be consistent with the colloid observations. These observations can be used to explain the characteristic magnetoresistance signal of a chevron column in a rotating field

    THE EFFECTS OF MUSCLE CROSS-SECTIONAL AREA ON THE PHYSICAL WORKING CAPACITY AT THE FATIGUE THRESHOLD

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    Purpose: The purpose of this study was to examine the effects of quadriceps cross-sectional area (CSA) of the dominant quadriceps muscle in the assessment of the physical working capacity at the fatigue threshold (PWCFT) during incremental cycle ergometry. Methods: Eighteen adults (9 men and 9 women; mean age ± SD = 20.5 ± 1.04 yr; mean body weight ± SD = 73.9 ± 18.2 kg; mean height ± SD = 172.3 ± 11.5 cm; mean dominant quadriceps CSA ± SD = 68.7 ± 14.5 cm2) performed an incremental cycle ergometry test to exhaustion while the electromyographic (EMG) signals were recorded from the vastus lateralis (VL) muscles. Fatiguing and non-fatiguing power outputs were differentiated by examining the slope coefficients for the EMG amplitude versus time relationship at each power output throughout the incremental cycle ergometry test. Quadriceps CSA was estimated from an equation. Subjects were divided into groups of small quadriceps CSA (57.3 ± 10.0 cm2) and large quadriceps CSA (80.0 ± 7.6 cm2). Results: Independent t-test results indicated no significant mean differences between the PWCFT for the large and small quadriceps CSA groups (p=0.456). Conclusion: The findings of the study suggest that muscle CSA may not have a significant effect on the assessment of the PWCFT, and therefore that PWCFT may be a determinant of neuromuscular fatigue independent of muscle CSA. Future research could explore the contributions of muscle fibertype predominance to CSA and PWCFT and provide more conclusive evidence relating these variables

    Sensory Communication

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    Contains table of contents for Section 2, an introduction and reports on twelve research projects.National Institutes of Health Grant R01 DC00117National Institutes of Health Grant R01 DC02032National Institutes of Health/National Institute of Deafness and Other Communication Disorders Grant 2 R01 DC00126National Institutes of Health Grant 2 R01 DC00270National Institutes of Health Contract N01 DC-5-2107National Institutes of Health Grant 2 R01 DC00100U.S. Navy - Office of Naval Research Grant N61339-96-K-0002U.S. Navy - Office of Naval Research Grant N61339-96-K-0003U.S. Navy - Office of Naval Research Grant N00014-97-1-0635U.S. Navy - Office of Naval Research Grant N00014-97-1-0655U.S. Navy - Office of Naval Research Subcontract 40167U.S. Navy - Office of Naval Research Grant N00014-96-1-0379U.S. Air Force - Office of Scientific Research Grant F49620-96-1-0202National Institutes of Health Grant RO1 NS33778Massachusetts General Hospital, Center for Innovative Minimally Invasive Therapy Research Fellowship Gran

    Sensory Communication

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    Contains table of contents for Section 2, an introduction and reports on fourteen research projects.National Institutes of Health Grant RO1 DC00117National Institutes of Health Grant RO1 DC02032National Institutes of Health/National Institute on Deafness and Other Communication Disorders Grant R01 DC00126National Institutes of Health Grant R01 DC00270National Institutes of Health Contract N01 DC52107U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-95-K-0014U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-96-K-0003U.S. Navy - Office of Naval Research Grant N00014-96-1-0379U.S. Air Force - Office of Scientific Research Grant F49620-95-1-0176U.S. Air Force - Office of Scientific Research Grant F49620-96-1-0202U.S. Navy - Office of Naval Research Subcontract 40167U.S. Navy - Office of Naval Research/Naval Air Warfare Center Contract N61339-96-K-0002National Institutes of Health Grant R01-NS33778U.S. Navy - Office of Naval Research Grant N00014-92-J-184

    Finishing the euchromatic sequence of the human genome

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    The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

    Exploring UK medical school differences: the MedDifs study of selection, teaching, student and F1 perceptions, postgraduate outcomes and fitness to practise.

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    BACKGROUND: Medical schools differ, particularly in their teaching, but it is unclear whether such differences matter, although influential claims are often made. The Medical School Differences (MedDifs) study brings together a wide range of measures of UK medical schools, including postgraduate performance, fitness to practise issues, specialty choice, preparedness, satisfaction, teaching styles, entry criteria and institutional factors. METHOD: Aggregated data were collected for 50 measures across 29 UK medical schools. Data include institutional history (e.g. rate of production of hospital and GP specialists in the past), curricular influences (e.g. PBL schools, spend per student, staff-student ratio), selection measures (e.g. entry grades), teaching and assessment (e.g. traditional vs PBL, specialty teaching, self-regulated learning), student satisfaction, Foundation selection scores, Foundation satisfaction, postgraduate examination performance and fitness to practise (postgraduate progression, GMC sanctions). Six specialties (General Practice, Psychiatry, Anaesthetics, Obstetrics and Gynaecology, Internal Medicine, Surgery) were examined in more detail. RESULTS: Medical school differences are stable across time (median alpha = 0.835). The 50 measures were highly correlated, 395 (32.2%) of 1225 correlations being significant with p < 0.05, and 201 (16.4%) reached a Tukey-adjusted criterion of p < 0.0025. Problem-based learning (PBL) schools differ on many measures, including lower performance on postgraduate assessments. While these are in part explained by lower entry grades, a surprising finding is that schools such as PBL schools which reported greater student satisfaction with feedback also showed lower performance at postgraduate examinations. More medical school teaching of psychiatry, surgery and anaesthetics did not result in more specialist trainees. Schools that taught more general practice did have more graduates entering GP training, but those graduates performed less well in MRCGP examinations, the negative correlation resulting from numbers of GP trainees and exam outcomes being affected both by non-traditional teaching and by greater historical production of GPs. Postgraduate exam outcomes were also higher in schools with more self-regulated learning, but lower in larger medical schools. A path model for 29 measures found a complex causal nexus, most measures causing or being caused by other measures. Postgraduate exam performance was influenced by earlier attainment, at entry to Foundation and entry to medical school (the so-called academic backbone), and by self-regulated learning. Foundation measures of satisfaction, including preparedness, had no subsequent influence on outcomes. Fitness to practise issues were more frequent in schools producing more male graduates and more GPs. CONCLUSIONS: Medical schools differ in large numbers of ways that are causally interconnected. Differences between schools in postgraduate examination performance, training problems and GMC sanctions have important implications for the quality of patient care and patient safety

    The Analysis of Teaching of Medical Schools (AToMS) survey: an analysis of 47,258 timetabled teaching events in 25 UK medical schools relating to timing, duration, teaching formats, teaching content, and problem-based learning.

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    BACKGROUND: What subjects UK medical schools teach, what ways they teach subjects, and how much they teach those subjects is unclear. Whether teaching differences matter is a separate, important question. This study provides a detailed picture of timetabled undergraduate teaching activity at 25 UK medical schools, particularly in relation to problem-based learning (PBL). METHOD: The Analysis of Teaching of Medical Schools (AToMS) survey used detailed timetables provided by 25 schools with standard 5-year courses. Timetabled teaching events were coded in terms of course year, duration, teaching format, and teaching content. Ten schools used PBL. Teaching times from timetables were validated against two other studies that had assessed GP teaching and lecture, seminar, and tutorial times. RESULTS: A total of 47,258 timetabled teaching events in the academic year 2014/2015 were analysed, including SSCs (student-selected components) and elective studies. A typical UK medical student receives 3960 timetabled hours of teaching during their 5-year course. There was a clear difference between the initial 2 years which mostly contained basic medical science content and the later 3 years which mostly consisted of clinical teaching, although some clinical teaching occurs in the first 2 years. Medical schools differed in duration, format, and content of teaching. Two main factors underlay most of the variation between schools, Traditional vs PBL teaching and Structured vs Unstructured teaching. A curriculum map comparing medical schools was constructed using those factors. PBL schools differed on a number of measures, having more PBL teaching time, fewer lectures, more GP teaching, less surgery, less formal teaching of basic science, and more sessions with unspecified content. DISCUSSION: UK medical schools differ in both format and content of teaching. PBL and non-PBL schools clearly differ, albeit with substantial variation within groups, and overlap in the middle. The important question of whether differences in teaching matter in terms of outcomes is analysed in a companion study (MedDifs) which examines how teaching differences relate to university infrastructure, entry requirements, student perceptions, and outcomes in Foundation Programme and postgraduate training

    Studying complex interactions among determinants of healthcare-seeking behaviours: self-medication for sexually transmitted infection symptoms in female sex workers.

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    OBJECTIVES: To describe the frequency and determinants of self-medication for symptoms of sexually transmitted infections (STI) in a female sex worker (FSW) population. To present a methodology exploring the best predictors as well as the interactions between determinants of self-medication. METHODS: A cross-sectional survey of 4153 FSW carried out in Peru. The prevalence of self-medication was estimated from the subsample of participants who had experienced symptoms of STI in the past 12 months (n=1601), and used successive logistic regression models to explore the determinants. RESULTS: Self-medication prevalence for a reported symptomatic episode during the past 12 months was 32.1% (95% CI 29.8 to 34.6). It was negatively correlated with work in brothels (adjusted odds ratio (OR) 0.51, 95% CI 0.28 to 0.93; p=0.028) and awareness of STI services available for FSW (adjusted OR 0.49, 95% CI 0.29 to 0.81; p=0.006). Other determinants were organised at different levels of proximity to the outcome creating pathways leading to self-medication. CONCLUSIONS: The importance of the staggered analysis presented in this study resides in its potential to improve the understanding of associations between determinants and, consequently, the targeting of interventions. The awareness of STI services available for FSW increases access to health care, which in turn decreases self-medication. In addition, the sharing of information that takes place between brothel-based FSW was also related to a diminishing prevalence of self-medication. These two main predictors provide an opportunity for prevention programmes, in particular those designed to be led by peers
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