This systematic review aims to assess the literature to determine the impact of EUS for diagnosing malignancy among indeterminate extrahepatic biliary strictures. A systematic review was performed using MEDLINE, EMBASE, Cochrane, and conference proceedings from inception to July 2016. Pooled results were calculated using random-effects model, and heterogeneity was explored using stratified meta-analysis and meta-regression. The main outcome was the incremental benefit of EUS (IBEUS) for the diagnosis of malignancy among patients who have undergone ERCP with brushing cytology for extrahepatic biliary strictures. Of 3131 identified citations, ten met the inclusion criteria and were included in the final analyses (study periods from 1998 to 2014). Pooled IBEUS estimate with the adjustment for publication bias was 14% (95% confidence interval, 7%–20%). Individual studies demonstrate that the IBEUS is greater for distal biliary strictures or when an extrinsic mass is identified on cross-sectional imaging. EUS increases the identification of malignancy for indeterminate biliary strictures following a nondiagnostic ERCP, particularly those that are distal or related to extrinsic compression.

O verweight and obesity affect more than one-third of the world's population. 1,2 Should current trends continue, it is projected that an estimated 38% of the world's adult population will be overweight and another 20% will be obese by 2030. 3 In the United States, projections based on recent trends forecast that nearly 50% of adults will be obese by 2030. 4 The National Weight Control Registry is the largest prospective investigation of long-term successful weight loss maintenance (WLM). This registry includes the behavioral and psychological characteristics of >10,000 people who have lost at least 30 lb and have kept the weight off for at least 1 year. Studies from the registry have identified that a program of regular exercise is a key characteristic of individuals who have been successful with WLM. [5][6][7] Most National Weight Control Registry subjects reported engaging in >1 hour of moderate-intensity physical activity per day. 6 Population studies on long-term WLM demonstrate a positive correlation between the amount of exercise completed and the percentage of maintained weight loss. [8][9][10][11][12][13][14] Because exercise must be ongoing to be effective, this perspective explores the importance of considering the biopsychosocial model and contextual factors when prescribing exercise for weight control as a means of enhancing exercise adherence and improving health outcomes.

This paper presents a one-dimensional model for the cooling of optical fibers. Heat transfer between the fiber, gas and wall, by conduction, convection, and radiation, are taken into account. The model offers advanced features such as multiple inlets and outlets. Six different pure gases or their mixtures may be used to study the effect of gas composition. The forced convection heat transfer coefficient is computed using the correlation for the forced convection in tubes and conduits. This correlation is then corrected to account for the enhanced heat transfer due to the motion of the fiber. This factor is determined from the limited experimental data available in the literature. The mathematical model consists of a system of ordinary differential equations and is solved using the LSODE solver. The model was used to study the effect of various operational parameters. The results show that at the typical conditions used in a commercial draw tower, Helium is the most effective cooling medium. A smaller diameter exchanger is more effective in cooling the fiber. More cooling is achieved if the incoming gas temperature is lower as well as if the cooler wall is kept at a lower temperature. The most critical factor is the fiber draw speed. At higher draw speeds, the residence time is low, which leads to shorter contact time for the fiber and gas to exchange heat. The effect of gas flow rate is not very significant, provided the flow regime is laminar. The turbulence flow regime is, in general, not desirable as it may cause vibrations, which is detrimental to fiber properties such as diameter and strength. Comparisons of the one-dimensional model results with the results of a two-dimensional model as well as simulations using Fluent, a commercial CFD package, are also presented. The results of these simulations may be used for an improved design of an exchanger, providing more efficient cooling of optical fiber. An improved design of exchanger will be the focus of future work in this area.

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