216 research outputs found
Dermatology residency selection criteria with an emphasis on program characteristics: a national program director survey.
Background. Dermatology residency programs are relatively diverse in their resident selection process. The authors investigated the importance of 25 dermatology residency selection criteria focusing on differences in program directors' (PDs') perception based on specific program demographics. Methods. This cross-sectional nationwide observational survey utilized a 41-item questionnaire that was developed by literature search, brainstorming sessions, and online expert reviews. The data were analyzed utilizing the reliability test, two-step clustering, and K-means methods as well as other methods. The main purpose of this study was to investigate the differences in PDs' perception regarding the importance of the selection criteria based on program demographics. Results. Ninety-five out of 114 PDs (83.3%) responded to the survey. The top five criteria for dermatology residency selection were interview, letters of recommendation, United States Medical Licensing Examination Step I scores, medical school transcripts, and clinical rotations. The following criteria were preferentially ranked based on different program characteristics: "advanced degrees," "interest in academics," "reputation of undergraduate and medical school," "prior unsuccessful attempts to match," and "number of publications." Conclusions. Our survey provides up-to-date factual data on dermatology PDs' perception in this regard. Dermatology residency programs may find the reported data useful in further optimizing their residency selection process
Force Control of a robot manipulator using a real-time PC- based Controller
This master thesis is based on an autonomous wheeled mobile manipulator project, directed in Tampere university of technology (TUT). In the beginning, we carried out a comprehensive study on the linux-based real-time operating systems, meanwhile existing limitation in the real-time operating system and real-time consideration in the programming of the control application has been surveyed in more details. Then, we studied force control strategies and control theories of the manipulators under contact forces. After that, manipulator dynamic equations and internal motion control loops were simulated using Simulink environment of Matlab. In this step, three scheme of controller with different area application were designed and was simulated on the manipulator Simulink model. The implementation part is based on the rapid prototyping method using Matlab/Simulink code generation products, firstly, the interfacing software between the manipulator joint actuators and the main controller software which is run in the RTLinux Xenomai was developed. In the next step, a similar interfacing application was developed for acquiring force data from the force torque sensor. In the next step, force torque sensor was calibrated using a calibration method according to gravity effects, then calibrated data was provided as measuring(sensory) input of the force controller software. In the final step, force control loop was closed around the motion controller loop and stiffness control scheme was achieved
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Investigation of Noise and Ride Quality Trends for Asphaltic Pavement Surface Types: Five-Year Results
Field data regarding tire/pavement noise, ride quality, and macrotexture were collected over five consecutive years from pavements in California placed with open-graded and other asphaltic mixes. The five-year data were analyzed to evaluate the ride quality and effectiveness of open-graded mixes in reducing noise compared to other asphalt surfaces, including dense- and gap-graded mixes, and to evaluate the pavement characteristics that affect tire/pavement noise. The analysis in this report is a supplement and update to four previous studies on the first four years of data collected, which are detailed in four separate reports. Models have been updated, with some changes in the use of condition survey variables. Conclusions are made regarding the performance of open-graded mixes and rubberized mixes (RAC-G), comparisons are made with dense-graded mixes (DGAC), and the effects of variables affecting tire/pavement noise are examined. Tire/pavement noise is greatly influenced by surface mix type and mix properties, age, traffic volume, and the presence of stresses indicated by pavement surface macrotexture, which served as a substitute for raveling in this study. Noise levels generally increased primarily with traffic volume and pavement age. Overall noise levels decreased with increased surface layer thickness and permeability (or air-void content)
Development of a Prediction Model for Skid Resistance of Asphalt Pavements
The skid resistance of asphalt pavement is a major characteristic that determines the driving safety on a road, especially under wet surface conditions. Skid resistance is primarily a function of the microtexture and macrotexture of a pavement surface. Microtexture is influenced by aggregate surface characteristics and is required to disrupt the continuity of surface water film and attain frictional resistance between the tire and the pavement surface. Macrotexture is affected mostly by mixture design or aggregate gradation and contributes to skid resistance by providing drainage paths of water that can be otherwise trapped between a tire and a pavement surface. The increase in macrotexture contributes to preventing hydroplaning and improving wet frictional resistance, particularly at high speeds. While much research has been conducted in the past to identify material factors that affect skid resistance, there is still a need to develop a model for predicting asphalt pavement skid resistance as a function of mixture characteristics and traffic level. The purpose of this study was to develop such a model based on extensive laboratory experiments and field measurements involving different mixture types and aggregate sources. The model incorporates functions that describe the resistance of aggregates to polishing and aggregate size distribution. The aggregate resistance to polishing was quantified by measuring aggregate texture using the Aggregate Imaging System (AIMS) before and after polishing in the Micro-Deval device. The analysis in this dissertation demonstrates how this model can be used to design mixtures and classify aggregates that provide desirable skid resistance levels
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Effects of Milling and Other Repairs on the Smoothness of Overlays on Asphalt Pavements from 2000 to 2009
The application of asphalt overlays comprises a significant percentage of the maintenance activities undertaken to improve the condition of existing asphalt pavements, and greater attention is now being paid to improving surface smoothness by constructing smoother overlays. The expected benefits of smoother overlays include longer service life due to decreased dynamic loading, improved fuel economy, and greater road-user comfort. In this study, data from the California Department of Transportation (Caltrans) Pavement Condition Survey (PCS) for projects built between 2000 and 2009 were used to investigate the effects of repairs, pavement pre-overlay smoothness (in terms of International Roughness Index, IRI), overlay mix type (dense-graded, gap-graded, open-graded), and binder type (rubberized versus conventional or polymer-modified) on initial post-construction overlay smoothness. The results are based on overlays constructed prior to implementation of the Caltrans smoothness specification for overlay construction. Linear mixed effects models were used in the analysis to take into account the variation across random effect variables. In this study, overlay smoothness was measured in terms of IRI. The analysis results indicated that the pavement pre-overlay IRI was the most important variable affecting overlay smoothness: pavements with lower pre-overlay IRI were smoother than those with higher pre-overlay IRI. When the pre-overlay condition was poor, increasing overlay thickness was also found to have a significant effect on post-overlay smoothness. In terms of pre-overlay repairs, analysis of Caltrans PCS data showed that overlays were smoother when digouts (milling and patching in the wheelpaths) were performed compared with milling of the entire surface prior to the overlay. The effects of overlay mix type and binder type were dependent on the pre-existing pavement condition and/or other factors
Development of an efficient hybrid GA-PSO approach applicable for well placement optimization
 When it comes to the economic efficiency of oil and gas field development, finding the optimum well locations that augment an economical cost function like net present value (NPV) is of paramount importance. Well location optimization has long been a challenging problem due to the heterogeneous nature of hydrocarbon reservoirs, economic criteria, and technical uncertainties. These complexities lead to an enormous number of possible solutions that must be evaluated using an evaluation function (e.g. a simulator). This makes it necessary to develop a powerful optimization algorithm into which a fast function evaluation tool is incorporated. The present study describes the application of a combination of the genetic algorithm (GA) and the particle swarm optimization (PSO) into a hybrid GA-PSO algorithm that is implemented in a streamline simulator to determine optimal locations for production and injection wells across heterogeneous reservoir models. Performance of the hybrid GA-PSO algorithm is then compared to that of the PSO and the GA separately. The results confirm that compared to conventional methods, the recommended method provides a fast and well-defined approach for production optimization complications.Cited as: Yazdanpanah, A., Rezaei, A., Mahdiyar, H., Kalantariasl, A. Development of an efficient hybrid GA-PSO approach applicable for well. Advances in Geo-Energy Research, 2019, 3(4): 365-374, doi: 10.26804/ager.2019.04.0
Report of the clinical features of patients with leptospirosis in Golestan, Iran, 2011-2015: Based on information available at the provincial health center
BACKGROUND: Leptospirosis is a zoonotic disease with a global distribution that is caused by pathogenic spirochetes of Leptospira. It has a global spread, but it is more common in warm and tropical regions. In developing countries such as Iran, it is considered as a work-related illness and occurs mostly in farmers, ranchers, slaughterhouse workers, butchers, and fishermen in the warm seasons of the year. The aim of this study was to report the information available at the provincial health center about the clinical features of patients with leptospirosis in Golestan province, Iran, from 2011 to 2015.METHODS: This cross-sectional descriptive study surveyed all patients with leptospirosis in Golestan provincial health center from 2011 to 2015. All information was collected by a self-designed checklist that its reliability was approved by three infectious specialists. In case of defective files, patients were contacted. The collected data were analyzed by an epidemiologist via SPSS software.RESULTS: In this study, during the years of 2011 to 2015, 75 cases of leptospirosis were recorded. 50 cases (66.6%) were men and 25 (33.3%) were women. The most common complaint of patients at referral was fever (70 cases, 93.33%). The most complained problem after fever (93.33%) was musculoskeletal pain and jaundice reported 57.33% and 54.66%, respectively.CONCLUSION: It is important to pay attention to this disease in farmers and villagers, especially in agricultural seasons. Due to the high prevalence, morbidity, and mortality of leptospirosis, early diagnosis based on common symptoms is important. Healthcare centers in each area are required to recognize common diseases to reduce irreversible complications
Laboratory Investigation of Fatigue Characteristics of Asphalt Mixtures with Steel Slag Aggregates
There are many steel-manufacturing factories in Iran. All of their byproducts, steel slag, are dumped randomly in open areas, causing many environmentally hazardous problems. This research is intended to study the effectiveness of using steel slag aggregate (SSA) in improving the engineering properties, especially fatigue life of Asphalt Concrete (AC) produced with steel slag. The research started by evaluating the physical properties of the steel slag aggregate. Then the 13 types of mixes which contain steel slag in portion of fine aggregates or in portion of coarse aggregates or in all portions of aggregates were tested. The effectiveness of the SSA was judged by the improvement in Marshall stability, indirect tensile strength, resilient modulus, and fatigue life of the AC samples. It was found that replacing the 50% of the limestone coarse or fine aggregate by SSA improved the mechanical properties of the AC mixes
Frequency and characteristics of Brucellosis in Golestan Province, Iran
BACKGROUND: Brucellosis is a common widespread zoonotic disease between humans and livestock with significant economic and health problems caused by various species of Brucella. The disease is a significant public health issue throughout the world and one of the most socioeconomic problems in many developing countries. This study aimed to report the information available at the Provincial Health Center about the frequency and characteristics of patients with Brucellosis in Golestan Province, Iran.METHODS: This study was analytic-descriptive cross-sectional. The study population included all patients with Brucellosis diagnosed from 2011 to 2015 in the health center of Golestan Province, based on the serological method. The data gathering tool was a questionnaire that included demographic information, clinical presentation and examinations, history of exposure, laboratory findings, and treatment protocols. Descriptive statistics were reported as frequency and mean ± standard deviation (SD) and analyzed by SPSS software.RESULTS: In this study, a total of 1788 cases of Brucellosis were reported. The number of male cases was 1163 (65.04%) and female cases were 625 (34.95%). People who had a history of contact with infected animals were younger than the others. Musculoskeletal pain (79.69%) and fever (76.45%) were the most commonly reported clinical symptoms.CONCLUSION: Overall, the results indicate that Brucellosis is still a health problem in the province. The high incidence of Brucellosis in villages, the lack of full coverage of animal vaccination, and the link between the disease and livestock businesses are significant
Report of the clinical features of patients with leptospirosis in Golestan, Iran, 2011-2015: Based on information available at the provincial health center
BACKGROUND: Leptospirosis is a zoonotic disease with a global distribution that is caused by pathogenic spirochetes of Leptospira. It has a global spread, but it is more common in warm and tropical regions. In developing countries such as Iran, it is considered as a work-related illness and occurs mostly in farmers, ranchers, slaughterhouse workers, butchers, and fishermen in the warm seasons of the year. The aim of this study was to report the information available at the provincial health center about the clinical features of patients with leptospirosis in Golestan province, Iran, from 2011 to 2015. METHODS: This cross-sectional descriptive study surveyed all patients with leptospirosis in Golestan provincial health center from 2011 to 2015. All information was collected by a self-designed checklist that its reliability was approved by three infectious specialists. In case of defective files, patients were contacted. The collected data were analyzed by an epidemiologist via SPSS software. RESULTS: In this study, during the years of 2011 to 2015, 75 cases of leptospirosis were recorded. 50 cases (66.6%) were men and 25 (33.3%) were women. The most common complaint of patients at referral was fever (70 cases, 93.33%). The most complained problem after fever (93.33%) was musculoskeletal pain and jaundice reported 57.33% and 54.66%, respectively. CONCLUSION: It is important to pay attention to this disease in farmers and villagers, especially in agricultural seasons. Due to the high prevalence, morbidity, and mortality of leptospirosis, early diagnosis based on common symptoms is important. Healthcare centers in each area are required to recognize common diseases to reduce irreversible complication
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