Subducted lithosphere under South America from multifrequency p wave tomography

We analyze mantle structure under South America in the DETOX-P1 seismic tomography model, a global-scale, multifrequency inversion of teleseismic P waves. DETOX-P1 inverts the most extensive data set of broadband, waveform-based traveltime measurements to date, complemented by analyst-picked traveltimes from the ISC-EHB catalog. The mantle under South America is sampled by ∼665,000 cross-correlation traveltimes measured on 529 South American broadband stations and on 5,389 stations elsewhere. By their locations, depths, and geometries, we distinguish four high-velocity provinces under South America, interpreted as subducted lithosphere (“slabs”). The deepest (∼1,800–1,200 km depth) and shallowest (<600 km) slab provinces are observed beneath the Andean Cordillera near the continent’s northwest coast. At intermediate depths (1,200–900 km, 900–600 km), two slab provinces are observed farther east, under Brazil, Bolivia and Venezuela, with links to the Caribbean. We interpret the slabs relative to South America’s paleo-position over time, exploring the hypothesis that slabs sank essentially vertically after widening by viscous deformation in the mantle transition zone. The shallowest slab province carries the geometric imprint of the continental margin and represents ocean-beneath-continent subduction during Cenozoic times. The deepest, farthest west slab complex formed under intra-oceanic trenches during late Jurassic and Cretaceous times, far west of South America’s paleo-position adjoined to Africa. The two intermediate slab complexes record the Cretaceous transition from westward intra-oceanic subduction to eastward subduction beneath South America. This geophysical inference matches geologic records of the transition from Jura-Cretaceous, extensional “intra-arc” basins to basin inversion and onset of the modern Andean arc ∼85 Ma

Clinical nutrition in primary care: An evaluation of resident physicians' attitudes and self-perceived proficiency.

There is little information regarding the impact of clinical nutrition training among medical residents. We aimed to evaluate the attitudes, self-perceived proficiency and knowledge of Swiss residents regarding clinical nutrition. Cross-sectional study conducted between June and September 2014 in two medical education facilities located in Lausanne, Switzerland. Attitudes, self-perceived proficiency and knowledge regarding clinical nutrition were assessed by questionnaire. Of the 88 internal medicine residents queried, 44 (50% response rate, 25 women, mean age 34 ± 4 years) answered the questionnaire. Three quarters of the residents were trained in Switzerland and one third reported receiving some training in clinical nutrition. Seven out of ten (70.5%) residents agreed that all doctors should know how to provide nutrition-based assessment, no matter what their specialty. Conversely, only one out of ten (11.4%) felt that physicians were adequately trained. No differences were found between genders or country of training regarding the answers provided. Residents in Lausanne perceive clinical nutrition in primary care as a priority but lack the confidence and training to effectively use clinical nutrition in their daily practice

When only the real thing will do: junior medical students’ learning from real patients

Bell, K., Boshuizen, H. P. A., Scherpbier, A. J. J. A., & Dornan, T. L. (2009). When only the real thing will do: junior medical students' learning from real patients. Medical Education, 43(11), 1036-1043. doi:10.1111/j.1365-2923.2009.03508.xOBJECTIVES This study aimed to explore how medical students experience contacts with real patients and what they learn from them. METHODS We carried out a post hoc, single-group study in one teaching sector of a 5-year, problem-based, horizontally integrated, outcome-based and community-oriented undergraduate programme, in which students lacked clinical exposure in the pre-clerkship phase. Subjects comprised five cohorts of students on their first clerkships. Data consisted of purposively selected, voluntary, self-report statements regarding real patient learning (RPL). Constant comparative analysis was performed by two independent researchers. RESULTS Respondents valued patients as an instructional resource that made learning more real. They reported learning through visual pattern recognition as well as through dialogue and physical examination. They more often used social than professional language to describe RPL. They reported affective outcomes including enhanced confidence, motivation, satisfaction and a sense of professional identity. They also reported cognitive outcomes including perspective, context, a temporal dimension, and an appreciation of complexity. Real patient learning helped respondents link theory learned earlier with reality as represented by verbal, visual and auditory experiences. It made learning easier, more meaningful and more focused. It helped respondents acquire complex skills and knowledge. Above all, RPL helped learners to remember subject matter. Most negative responses concerned the difficulty of acquiring appropriate experience, but RPL made a minority of respondents feel uncomfortable and incompetent. CONCLUSIONS Real patient learning led to a rich variety of learning outcomes, of which at least some medical students showed high metacognitive awareness. Sensitivity from clinical mentors towards the positive and negative outcomes of RPL reported here could support reflective clinical learning

Secondary prevention of heart disease – knowledge among cardiologists and Ω-3 (Omega-3) fatty acid prescribing behaviors in Karachi, Pakistan

<p>Abstract</p> <p>Background</p> <p>The use of omega-3 fatty acids is a currently proven strategy for secondary prevention of heart disease. The prescription practices for this important nutraceutical is not currently known. It is imperative to assess the knowledge of cardiologists regarding the benefits of omega-3 fatty acids and to determine the frequency of its prescription. The aim of the study was to determine the practices and associations of dietary fish prescribing among cardiologists of Karachi and to assess their knowledge of fish oil supplementation and attitudes toward dietary practices.</p> <p>Methods</p> <p>A cross sectional survey was conducted during the period of January to March, 2008. A self report questionnaire was employed. All practicing cardiologists of Karachi were included in the study. Multiple logistic regression analysis was performed to determine the independent factors associated with high fish prescribers.</p> <p>Results</p> <p>The sample comprised of a total of 163 cardiologists practicing in Karachi, Pakistan. Most (73.6%) of the cardiologists fell in the age range of 28 – 45 years and were male (90.8%). High fish prescribers only comprised 36.2% of the respondents. After adjusting for age and gender, multivariate analysis revealed that only the variable of knowledge about fish oil's role in reducing sudden cardiac death was independently associated with high fish prescribers OR = 6.38 [95% CI 2.58–15.78].</p> <p>Conclusion</p> <p>The level of knowledge about the benefits of omega-3 fatty acids is high and the cardiologists harbor a favorable attitude towards dispensing dietary fish advice. However, the prescription practices are less than optimal and not concordant with recommendations of organisations such as the American Heart Association and National Heart Foundation of Australia. The knowledge of prevention of sudden cardiac death in CVD patients has been identified as an important predictor of high fish prescription. This particular life-saving property of omega-3 fatty acids should be the focus of any implemented educational strategy targeted to improve secondary CVD prevention via omega-3 fatty acid supplementation.</p

Can I cut it? Medical students' perceptions of surgeons and surgical careers

Abstract Background Recent years have seen a significant drop in applications to surgical residencies. Existing research has yet to explain how medical students make career decisions. This qualitative study explores students' perceptions of surgery and surgeons, and the influence of stereotypes on career decisions. Methods Exploratory questionnaires captured students' perceptions of surgeons and surgery. Questionnaire data informed individual interviews, exploring students' perceptions in depth. Rigorous qualitative interrogation of interviews identified emergent themes from which a cohesive analysis was synthesized. Results Respondents held uniform stereotypes of surgeons as self-confident and intimidating; surgery was competitive, masculine, and required sacrifice. To succeed in surgery, students felt they must fit these stereotypes, excluding those unwilling, or who felt unable, to conform. Deviating from the stereotypes required displaying such characteristics to a level exceptional even for surgery; consequently, surgery was neither an attractive nor realistic career option. Conclusions Strong stereotypes of surgery deterred students from a surgical career. As a field, surgery must actively engage medical students to encourage participation and dispel negative stereotypes that are damaging recruitment into surgery

Why medical students choose psychiatry - a 20 country cross-sectional survey

BACKGROUND: Recruitment to psychiatry is insufficient to meet projected mental health service needs world-wide. We report on the career plans of final year medical students from 20 countries, investigating factors identified from the literature which influence psychiatric career choice. METHODS: Cross sectional electronic or paper survey. Subjects were final year medical students at 46 medical schools in participating countries. We assessed students' career intentions, motivations, medical school teaching and exposure to psychiatry. We assessed students' attitudes and personality factors. The main outcome measure was likelihood of specializing in psychiatry. Multilevel logistic regression was used to examine the joint effect of factors upon the main outcome. RESULTS: 2198 of 9135 (24%) of students responded (range 4 to 91%) across the countries. Internationally 4.5% of students definitely considered psychiatry as a career (range 1 to 12%). 19% of students (range 0 to 33%) were "quite likely", and 25% were "definitely not" considering psychiatry. Female gender, experience of mental/physical illness, media portrayal of doctors, and positive attitudes to psychiatry, but not personality factors, were associated with choosing psychiatry. Quality of psychiatric placement (correlation coefficient = 0.22, p < 0.001) and number of placements (correlation coefficient =0.21, p < 0.001) were associated with higher ATP scores. During medical school, experience of psychiatric enrichment activities (special studies modules and university psychiatry clubs), experience of acutely unwell patients and perceived clinical responsibility were all associated with choice of psychiatry.Multilevel logistic regression revealed six factors associated with students choosing psychiatry: importance of own vocation, odds ratio (OR) 3.01, 95% CI 1.61 to 5.91, p < 0.001); interest in psychiatry before medical school, OR 10.8 (5.38 to 21.8, p < 0.001); undertaking a psychiatry special study module, OR 1.45 (1.05 to 2.01, p = 0.03) or elective OR 4.28 (2.87- 6.38, p < 0.001); membership of a university psychiatry club, OR 3.25 (2.87 to 6.38, p < 0.001); and exposure to didactic teaching, OR 0.54 (0.40 to 0.72, p < 0.001). CONCLUSIONS: We report factors relevant to medical student selection and psychiatry teaching which affect career choice. Addressing these factors may improve recruitment to psychiatry internationally

Tomotectonics of Cordilleran North America since Jurassic times: double-sided subduction, archipelago collisions, and Baja-BC translation

Tomotectonics uses deep mantle structure in order to hindcast paleo-trenches, by spatially superposing subducted lithosphere (slabs) imaged by seismic tomography with plate reconstructions at the surface. The two geophysical datasets combined make predictions about geologic events, specifically about volcanic arcs and their collisions with continents. The tomotectonic null hypothesis is simple, predictive and testable. It uses land geological observations for validation. We explain the method, with a clear conceptual separation of its hypothesis-generating stage (using geophysics and the hypothesis of vertical slab sinking) from its subsequent hypothesis-testing stage (using geological observations from accretionary orogens). With the North American Cordillera as a case study, we generate a full suite of tomotectonic inferences on the slab assemblage that now occupies the mantle under North America to depths of 1800-2000 km. We reason why this assemblage originated as a completely intra-oceanic archipelago of paleo-trenches at a time of worldwide tectonic reorganization: around 200-170 Ma, when the Atlantic began to spread and the Pacific plate was born. An Archipelago is circumscribed by trenches that pull in seafloor from (at least) two sides: here, roughly from the east and from the west. North America was pulled westward by, and overrode, the westward-subducting arcs. These collisions since ~150 Ma caused the Nevadan and Sevier orogenies, and spawned the eastward-subducting arc that built Sierra Nevada Batholith ~120-80 Ma. From ~110-50 Ma, the continent collided with the arc of future Central Alaska and with the Farallon arc of the Pacific Northwest, which sat offshore until ~90-50 Ma. Override of this double-sided arc pair enabled a range of collision styles, including the Baja-BC northward sprint and its accretion to Central Alaska. Tomotectonics infers large-scale northward displacement of Insular Superterrane since its accretion, which provides independent support for the “Baja-BC” hypothesis of paleomagnetism