21,105 research outputs found

    Dancing Between the Purist and the Practical: Teaching Evidence- Based Medicine in the 3rd Year Family Medicine Clerkship

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    OBJECTIVE: To teach 3rd year medical students in a Family Medicine rotation the concepts and methods required to practice Evidence-Based Medicine and how to search for that evidence. The course was developed with an emphasis on finding resources and included an extensive epidemiological and statistical component. Using student evaluations, the evolution over five years will be explored. METHODS: The didactic and experimental curriculum was developed with a strict interpretation of search strategies and EBM philosophy and rationale. In 1999, the class contained a detailed component on epidemiology and statistical interpretation of the four clinical study categories (etiology, diagnosis, therapy and prognosis). Following each session, student evaluations were solicited and changes were made to the curriculum based on student feedback and follow-up faculty discussion. Today, a more treatment-centered ethics-based curriculum is taught. While Evidence-Based vocabulary and some statistics such as Absolute Risk and Number Needed to Treat and Harm are included, emphasis is now placed on teaching students to look for good evidence and to use these findings within an effective patient interaction. Collected student evaluations from across the five-year time span will be analyzed to demonstrate the evolutionary steps of the curriculum. RESULTS & CONCLUSIONS: “More time for searching!” This is always a top comment on student evaluations. Ways to make this happen are consistently being identified and put into practice. As class time is limited, what is taught and how it is taught has become very selective. One recently incorporated tool is the use of a pre-session WebCT-based orientation. Material is always being added within this format to free up class time for more interactive practice. Two other practical content areas that have recently been introduced into the course are a) talking with patients about relative risk and b) understanding bias in the medical literature. The very simple evaluation form remains a device with which to collect further student feedback. The course will continue to be updated as EBM methodologies and outlooks within the medical community change and grow

    Exact asymptotic expansions for the cylindrical Poisson-Boltzmann equation

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    The mathematical theory of integrable Painleve/Toda type systems sheds new light on the behavior of solutions to the Poisson-Boltzmann equation for the potential due to a long rod-like macroion. We investigate here the case of symmetric electrolytes together with that of 1:2 and 2:1 salts. Short and large scale features are analyzed, with a particular emphasis on the low salinity regime. Analytical expansions are derived for several quantities relevant for polyelectrolytes theory, such as the Manning radius. In addition, accurate and practical expressions are worked out for the electrostatic potential, which improve upon previous work and cover the full range of radial distances

    Disparity in the natural cycles of Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis.

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    We studied the prevalence of Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis (HGE) among questing nymphal and adult Ixodes scapularis ticks of the same generation and the infectivity of wild white-footed mice for ticks feeding on them. The prevalence of B. burgdorferi infection in host-seeking ticks increased less than twofold from nymphal (31% to 33%) to adult (52% to 56%) stage, and 52% of white-footed mice were infected. Prevalence of the agent of HGE increased 4.5- to 10.6-fold from nymphal (1.5% to 1.8%) to adult stage (7.6% to 19.0%), while only 18% of mice were infectious to ticks. B. burgdorferi infection was more common in mouse-fed ticks than in ticks collected from vegetation, whereas the agent of HGE was half as common in mouse-fed ticks as in ticks collected from vegetation. The different prevalence in nature of these pathogens in ticks suggests that their maintenance cycles are also different

    A Distributed Message Passing Computational and I/O Engine for Real-Time Motion Control

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    This paper illustrates the use of the Yale XP/DCS - a dual board real-time distributed control module based upon the INMOS Transputer family of micoprocessors - for high performance real-time motion control applications. The XP/DCS complements the the Transputer’s 1.5 Mflop computational rate and four independent on-chip 20 Mbps DMA communication engines, by providing a bidirectional latched 32 bit bus extension with full handshaking support for easy customization of the I/O capabilities of any node. After contrasting this design with commercially available alternatives we describe three particular applications presently underway in the Yale Robotics Laboratory. We conclude by reporting some initial experiments concerning the effect of code distribution and message passing protocols upon sampling rate. For more information: Kod*La

    Heat exchange mediated by a quantum system

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    We consider heat transfer between two thermal reservoirs mediated by a quantum system using the generalized quantum Langevin equation. The thermal reservoirs are treated as ensembles of oscillators within the framework of the Drude-Ullersma model. General expressions for the heat current and thermal conductance are obtained for arbitrary coupling strength between the reservoirs and the mediator and for different temperature regimes. As an application of these results we discuss the origin of Fourier's law in a chain of large, but finite subsystems coupled to each other by the quantum mediators. We also address a question of anomalously large heat current between the STM tip and substrate found in a recent experiment. The question of minimum thermal conductivity is revisited in the framework of scaling theory as a potential application of the developed approach.Comment: 16 pages, 6 figure

    Elastic Buckling Under Combined Stresses of Flat Plates with Integral Waffle-like Stiffening

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    Theory and experiment were compared and found in good agreement for the elastic buckling under combined stresses of long flat plates with integral waffle-like stiffening in a variety of configurations. For such flat plates, 45 degree waffle stiffening was found to be the most effective of the configurations for the proportions considered over the widest range of combinations of compression and shear

    Control of deep-sea benthic community structure by oxygen and organic-matter gradients in the eastern Pacific Ocean

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    At boundaries of oxygen minimum zones (OMZs), bathyal faunas experience steep gradients in oxygen and organic-matter availability. The present study compares changes in microbial, meiofaunal, macrofaunal and megafaunal benthic assemblages along these gradients on Volcano 7, a 2.3-km high seamount in the eastern tropical Pacific. Faunal tolerance to dysaerobic (low oxygen) conditions varies with organism size; microbial and meiofaunal abundances are less affected than macro- and megafaunal abundances. At the exceedingly low concentrations (\u3c0.1 ml/l) encountered on the upper summit of Volcano 7, oxygen appears to exert primary control over abundance, composition and diversity of macrofauna, overriding other factors such as food availability and sediment grain size. When oxygen concentration is sufficient, food availability in sediments (indicated by the presence of labile material such as chlorophyll a) is highly correlated with meiofaunal and macrofaunal abundance. Four distinct physical zones were identified on Volcano 7: (1) the coarse-grained upper summit zone (730–770 m) where near-bottom oxygen concentrations were usually lowest (often \u3c0.1 ml/l) and organic-matter (% organic carbon and chlorophyll a) availability was high, (2) the coarse-grained lower summit (770–1000 m) where near-bottom oxygen concentrations were usually slightly higher (0.11 to 0.16 ml/l) and organic-matter availability remained high, (3) the coarse-grained flank (1000–2000 m) where oxygen concentration was intermediate (0.7–0.9 ml/l) and sediment organic-matter content was very low, and (4) the finer-grained base (2000–3500 m) where oxygen values exceeded 2.5 ml/l, sediment organic carbon was moderate, and chlorophyll a was low. Abundances of larger forms (megafauna and macrofauna) were severely reduced on the upper summit, but attained high values (2.25/m2 and 8,457/m2 respectively) just tens of meters below. The smaller forms (bacteria and meiofauna) attained peak abundances on the low-oxygen upper summit, however, abundances of harpacticoid copepods were greatly reduced on the upper and lower summit, presumably due to oxygen limitation. Macrofaunal abundance and diversity patterns along the Volcano 7 oxygen/enrichment gradient resembled those typically observed along shallow-water gradients of organic pollution. Low densities of a few soft-bodied, low-oxygen tolerant species resided on the upper summit, a high-density, low-diversity assemblage inhabited the lower summit, and low-density, high-diversity assemblages occupied the flank and base sediments. The infaunal communities on Volcano 7 support the idea that OMZ boundaries are regions of enhanced biological activity. Modern faunal distributions and biogenic structures at OMZ boundaries may be useful in reconstructing oxygenation histories of ancient marine basins

    Implementasi Elemen Tetrahedron Linear Dan Kuadratik Untuk Analisis Tegangan Tiga Dimensi Dengan Menggunakan Program Matlab Dan Gid

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    Metode elemen hingga (MEH) saat ini telah populer digunakan untuk memecahkan masalah-masalah yang sulit diselesaikan dengan metode analitik. Salah satu permasalahan yang sulit adalah objek tiga dimensi yang dapat ataupun tidak dapat dimodelkan dalam satu ataupun dua dimensi dimana permodelan tiga dimensi yang paling representatif. Dengan demikian dalam studi ini dibuat program untuk menyelesaikan permasalahan permodelan tiga dimensi dengan mengunakan elemen tetrahedron linier dan kuadratik. Analisis statik linier 3D solid diimplementasikan dalam program MATLAB, sedangkan pre-process dan post-process dengan program GiD. Keakuratan dan konvergensi MEH 3D solids ini diuji dengan menyelesaikan berbagai benchmark problems. Hasil-hasil pengujian menunjukkan bahwa MEH 3D solids mampu untuk mencapai hasil diharapkan dengan material isotropik maupun orthotropik. Penggunaan elemen kuadratik mampu mencapai hasil yang diharapkan lebih cepat dari elemen linier, sehingga penggunaan elemen kuadratik lebih efisien. Hasil yang didapat dengan elemen kuadratik cenderung konvergen di atas hasil referensi. Program yang dibuat diharapkan menjadi alternatif dalam analsis permodelan tiga dimensi

    Spin-down evolution and radio disappearance of the magnetar PSR J1622-4950

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    We report on 2.4 yr of radio timing measurements of the magnetar PSR J1622-4950 using the Parkes telescope, between 2011 November and 2014 March. During this period the torque on the neutron star (inferred from the rotational frequency derivative) varied greatly, though much less erratically than in the 2 yr following its discovery in 2009. During the last year of our measurements the frequency derivative decreased in magnitude monotonically by 20\%, to a value of 1.3×1013-1.3\times10^{-13} s2^{-2}, a factor of 8 smaller than when discovered. The flux density continued to vary greatly during our monitoring through 2014 March, reaching a relatively steady low level after late 2012. The pulse profile varied secularly on a similar timescale as the flux density and torque. A relatively rapid transition in all three properties is evident in early 2013. After PSR J1622-4950 was detected in all of our 87 observations up to 2014 March, we did not detect the magnetar in our resumed monitoring starting in 2015 January and have not detected it in any of the 30 observations done through 2016 September.Comment: 8 pages, 5 figures, submitted to Ap
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