99 research outputs found

    Designing an Agent for Information Extraction from Persian E-shops

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    E-shops are among the most conventional applications of Electronic Commerce. In these shops, the buyers search for their goods through key words or classifications and read the product description provided by the sellers. Though, when the number of items is high, this gets to be difficult for the users. On the one hand, there are too many e-shops, and browsing in these shops to find the best and most appropriate goods is a difficult and time-consuming process. On the other hand, product descriptions are not the same in different websites, and there are different product forms. This study investigates about products and sellers in various websites based on the conditions and user requirements through software agents which present the extracted information in the form of a table to the users which enables them to compare prices and each seller’s conditions without spending too much time for browsing. Using this method increases precision and recall indices comparing to a conventional user browsing

    Electron Transport in Quantum Systems with Interaction

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    Prevalence of Self-medication with Antibiotics amongst Clients Referred to Outpatient University Dental Clinics in Iranian Population: A Questionnaire-based Study

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    Introduction: Self-medication with antibiotics may increase the risk of inappropriate use and development of antibiotic-resistant bacteria. The aim of this study was to determine the prevalence of self-medication with antibiotics amongst dental outpatients in Iranian population.  Methods and Materials: One thousand and two hundred of dentistry patients, who were referred to dental school clinics in ten major provinces of Iran, participated in this study. A valid self-administered questionnaire regarding self-medication with antibiotics in case of dental pain was used to collect data. Data were analysed using descriptive statistics and Logistic regression analysis. Results: In our study population, the prevalence of self-medication was 42.6%. Amongst the Iranian cities, the highest prevalence of self-medication with antibiotics belonged to the city of Bandar Abbas (64%) and the lowest was seen in the city of Kerman (27.3%). Men were more likely to take antibiotics. Amoxicillin was the mostly used antibiotic. Severe pain, previous self-medications and high costs of dental visits were the most common reasons for self-medication with antibiotics in the investigated population. In addition, the present study showed that marriage, acceptable financial status and high level of education could decrease self-medication with antibiotics. Conclusions: In the current investigation, an alarming fact was that self-medication for dental problems seemed very common amongst the studied population. One of its most important consequences was bacterial resistance. Therefore, there should be plans to promote and prioritize public health awareness and encourage general public’s motivation to reduce the practice of self-medication.Keywords: Antibiotics; Dental Clinics; Prevalence; Self-medicatio

    Vortex formation and dissolution in sheared sands

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    Using digital image correlation, we track the displacement fluctuations within a persistent shear band in a dense sand specimen bounded by glass walls undergoing plane strain compression. The data evidences a clear, systematic, temporally recurring pattern of vortex formation, dissolution, and reformation throughout macroscopic softening and critical state regimes. During softening, locally affine deformation zones are observed at various locations along the shear band, which we argue to be kinematic signatures of semi-stable force chains. Force chain collapse then occurs, inducing vortex formation. Local jamming at the conflux of opposing displacements between adjacent vortices arrests the vortices, providing an avenue for potential new force chains to form amidst these jammed regions. The process repeats itself temporally throughout the critical state. The pattern further correlates with fluctuations in macroscopic shear stress. We characterize the nature of the observed vortices, as they are different in our sands comprised of irregular shaped particles, as compared to previous observations from experiments and numerical simulations which involved circular or rounded particles. The results provide an interesting benchmark for behavior of non-circular/non-spherical particles undergoing shear.National Science Foundation (U.S.) (grant CMMI-0748284)University of Southern CaliforniaUniversity of Southern California Women in Science and Engineering (WiSE) Progra

    Analysis of wind turbines under harsh operation conditions

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    This project focuses on the harsh operational conditions that sometimes lead to gearbox and bearing failures before their expected lifespan have been reached. Individual wind turbines that are subjected to extreme wind conditions and other severe operational conditions have been identified in close cooperation with wind turbine operators. Methods for determining the operational severity from data acquired during operation have been developed. Raw measured data have been processed and compared to the assumed data that were used in the wind turbine design process. Feedbacks from maintenance reports have been used to strengthen the relevance of these indices. A generic V90 turbine model has been created for the simulations using both FAST and VIDYN aero elastic simulation codes. The wind turbine dynamical behaviour has been analysed in arbitrary wind conditions and grid dynamics.The assessment has been made using 17 wind turbines of same design but with different operational conditions. The data from these turbines have been compared and comparison has also been made using simulated data for complex and flat terrains. The results show that the complex terrain increases the fatigue on the gearbox shaft and the fluctuation of wind direction in the complex terrain is much higher than for the flat terrain, resulting in more destructive fatigue loads. Simulation also shows that de-rating of the turbine has a significant impact on the loads in the drive train but no significant impact on the fatigue loads on the nacelle.There are different systems running for capturing operational data during operation. Normally the system stores only one measurement data point at each 20 seconds, i.e. 0.05 Hz. Then it is difficult to observe any details related to loads based on turbulence or other environment or technical conditions. For that reason, the project has managed to get higher resolution measurement data, 1 Hz sample rate, for specific turbines in the available fleets.The complex topography of a specific wind farm was extracted from LASer data and it was imported into the Computational Fluid Dynamics (CFD) software, STAR-CCM+, to generate the computational wind grid for the numerical simulations. The on-site meteorology mast data, provided by project partners, were used to determine the dominant mean wind speed/direction and turbulence intensity.A system simulation model in FAST or VIDYN can reasonably well predict the hub forces and mechanical torque of a Vestas V90 turbine under different kind of wind load in operation. A turbine designer is allowed to use any specific wind conditions as input for the load calculations. It might be outside the wind classes specified in IEC-61400-1 and therefore denoted class S, where the specific input conditions are stated. Using the calculated data for the complex terrain, a class 3S turbine has been defined with turbulence intensity, TI=0.17, shear α = 0.34 in comparison with standard wind turbine class 3A with TI=0.16 and α = 0.20. When using these input conditions, a fatigue load comparison and evaluation has been done. It shows that both drive torque and tower top bending moment increase with about 6 percent when class3S is used

    Determination of titanium in orthodontic with modified graphene paste electrode and ionic liquid by potentiometric method

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    Two new potentiometric methods for determination of titanium in pure form and in its pharmaceutical form are developed. In the first method, new modified carbon paste electrode based on(SAPD) as a chemical modifier. The construction of carbon paste electrodetitanium ion-selective electrode and its use in the potentiometric determination of titanium in pharmaceutical preparations and orthodontic cages is described. The electrode displays a linear log [Ti3+] versus EMF response over a wide concentration range of 4.1×10−7 to 1.2×10−3 with nernstian slope of 19.1±0.1 mV/decade with limit of detection 1.1×10−7 over the pH range 3.8–7.8; a response time of <10 s; and use for at least 3 months without any significant potential divergence the presence of the complex Ti(OH)2+ ion explains the slope of the response curve. The proposed sensor shows reasonable discrimination ability. The modified electrode was applied as indicator electrode to determine Ti(III) in aqueous samples with satisfactory results

    Silk-Based Biopolymers Promise Extensive Biomedical Applications in Tissue Engineering, Drug Delivery, and BioMEMS

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    As an FDA-approved biopolymer, silk has been contemplated for a wide range of applications based on its unique merits, such as biocompatibility, biodegradability, and piezoelectricity. As silk, in both crystalline structure and amorphous state, exhibits unique physical, mechanical, and biological properties (promoting cell migration, differentiation, growth, and protein-surface interaction), it is fruitful to understand its potential applications. Sensors, actuators, and drug delivery systems are the best in case. As such, the current effort first introduces silk fibroin (SF) and delineates its characteristics. It then explores the extensive use of this biomaterial in tissue engineering approaches, in addition to its biosensor and electro-active wearable bioelectronic application. To this end, the SF application in cardiovascular, skin, cartilage, and drug delivery systems for cancer therapy and wound healing was studied precisely. Compositing any type of other variables to induce a specific application or improve any SF barriers, namely its hydrophobicity, poor electrical conductivity, or tuning its mechanical properties, especially in tissue engineering applications, has also been discussed wherever it is deemed informative.</p

    Global burden of chronic respiratory diseases and risk factors, 1990–2019: an update from the Global Burden of Disease Study 2019

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    Background Updated data on chronic respiratory diseases (CRDs) are vital in their prevention, control, and treatment in the path to achieving the third UN Sustainable Development Goals (SDGs), a one-third reduction in premature mortality from non-communicable diseases by 2030. We provided global, regional, and national estimates of the burden of CRDs and their attributable risks from 1990 to 2019. Methods Using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we estimated mortality, years lived with disability, years of life lost, disability-adjusted life years (DALYs), prevalence, and incidence of CRDs, i.e. chronic obstructive pulmonary disease (COPD), asthma, pneumoconiosis, interstitial lung disease and pulmonary sarcoidosis, and other CRDs, from 1990 to 2019 by sex, age, region, and Socio-demographic Index (SDI) in 204 countries and territories. Deaths and DALYs from CRDs attributable to each risk factor were estimated according to relative risks, risk exposure, and the theoretical minimum risk exposure level input. Findings In 2019, CRDs were the third leading cause of death responsible for 4.0 million deaths (95% uncertainty interval 3.6–4.3) with a prevalence of 454.6 million cases (417.4–499.1) globally. While the total deaths and prevalence of CRDs have increased by 28.5% and 39.8%, the age-standardised rates have dropped by 41.7% and 16.9% from 1990 to 2019, respectively. COPD, with 212.3 million (200.4–225.1) prevalent cases, was the primary cause of deaths from CRDs, accounting for 3.3 million (2.9–3.6) deaths. With 262.4 million (224.1–309.5) prevalent cases, asthma had the highest prevalence among CRDs. The age-standardised rates of all burden measures of COPD, asthma, and pneumoconiosis have reduced globally from 1990 to 2019. Nevertheless, the age-standardised rates of incidence and prevalence of interstitial lung disease and pulmonary sarcoidosis have increased throughout this period. Low- and low-middle SDI countries had the highest age-standardised death and DALYs rates while the high SDI quintile had the highest prevalence rate of CRDs. The highest deaths and DALYs from CRDs were attributed to smoking globally, followed by air pollution and occupational risks. Non-optimal temperature and high body-mass index were additional risk factors for COPD and asthma, respectively. Interpretation Albeit the age-standardised prevalence, death, and DALYs rates of CRDs have decreased, they still cause a substantial burden and deaths worldwide. The high death and DALYs rates in low and low-middle SDI countries highlights the urgent need for improved preventive, diagnostic, and therapeutic measures. Global strategies for tobacco control, enhancing air quality, reducing occupational hazards, and fostering clean cooking fuels are crucial steps in reducing the burden of CRDs, especially in low- and lower-middle income countries. Funding Bill & Melinda Gates Foundation

    Global, regional, and national mortality due to unintentional carbon monoxide poisoning, 2000–2021: results from the Global Burden of Disease Study 2021

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    Background Unintentional carbon monoxide poisoning is a largely preventable cause of death that has received insufficient attention. We aimed to conduct a comprehensive global analysis of the demographic, temporal, and geographical patterns of fatal unintentional carbon monoxide poisoning from 2000 to 2021. Methods As part of the latest Global Burden of Diseases, Injuries, and Risk Factors Study (GBD), unintentional carbon monoxide poisoning mortality was quantified using the GBD cause of death ensemble modelling strategy. Vital registration data and covariates with an epidemiological link to unintentional carbon monoxide poisoning informed the estimates of death counts and mortality rates for all locations, sexes, ages, and years included in the GBD. Years of life lost (YLLs) were estimated by multiplying deaths by remaining standard life expectancy at age of death. Population attributable fractions (PAFs) for unintentional carbon monoxide poisoning deaths due to occupational injuries and high alcohol use were estimated. Findings In 2021, the global mortality rate due to unintentional carbon monoxide poisoning was 0·366 per 100 000 (95% uncertainty interval 0·276–0·415), with 28 900 deaths (21 700–32 800) and 1·18 million YLLs (0·886–1·35) across all ages. Nearly 70% of deaths occurred in males (20 100 [15 800–24 000]), and the 50–54-year age group had the largest number of deaths (2210 [1660–2590]). The highest mortality rate was in those aged 85 years or older with 1·96 deaths (1·38–2·32) per 100 000. Eastern Europe had the highest age-standardised mortality rate at 2·12 deaths (1·98–2·30) per 100 000. Globally, there was a 53·5% (46·2–63·7) decrease in the age-standardised mortality rate from 2000 to 2021, although this decline was not uniform across regions. The overall PAFs for occupational injuries and high alcohol use were 13·6% (11·9–16·0) and 3·5% (1·4–6·2), respectively. Interpretation Improvements in unintentional carbon monoxide poisoning mortality rates have been inconsistent across regions and over time since 2000. Given that unintentional carbon monoxide poisoning is almost entirely preventable, policy-level interventions that lower the risk of carbon monoxide poisoning events should be prioritised, such as those that increase access to improved heating and cooking devices, reduce carbon monoxide emissions from generators, and mandate use of carbon monoxide alarms.publishedVersio

    Global burden of chronic respiratory diseases and risk factors, 1990–2019: an update from the Global Burden of Disease Study 2019

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    Background: Updated data on chronic respiratory diseases (CRDs) are vital in their prevention, control, and treatment in the path to achieving the third UN Sustainable Development Goals (SDGs), a one-third reduction in premature mortality from non-communicable diseases by 2030. We provided global, regional, and national estimates of the burden of CRDs and their attributable risks from 1990 to 2019. Methods: Using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we estimated mortality, years lived with disability, years of life lost, disability-adjusted life years (DALYs), prevalence, and incidence of CRDs, i.e. chronic obstructive pulmonary disease (COPD), asthma, pneumoconiosis, interstitial lung disease and pulmonary sarcoidosis, and other CRDs, from 1990 to 2019 by sex, age, region, and Socio-demographic Index (SDI) in 204 countries and territories. Deaths and DALYs from CRDs attributable to each risk factor were estimated according to relative risks, risk exposure, and the theoretical minimum risk exposure level input. Findings: In 2019, CRDs were the third leading cause of death responsible for 4.0 million deaths (95% uncertainty interval 3.6–4.3) with a prevalence of 454.6 million cases (417.4–499.1) globally. While the total deaths and prevalence of CRDs have increased by 28.5% and 39.8%, the age-standardised rates have dropped by 41.7% and 16.9% from 1990 to 2019, respectively. COPD, with 212.3 million (200.4–225.1) prevalent cases, was the primary cause of deaths from CRDs, accounting for 3.3 million (2.9–3.6) deaths. With 262.4 million (224.1–309.5) prevalent cases, asthma had the highest prevalence among CRDs. The age-standardised rates of all burden measures of COPD, asthma, and pneumoconiosis have reduced globally from 1990 to 2019. Nevertheless, the age-standardised rates of incidence and prevalence of interstitial lung disease and pulmonary sarcoidosis have increased throughout this period. Low- and low-middle SDI countries had the highest age-standardised death and DALYs rates while the high SDI quintile had the highest prevalence rate of CRDs. The highest deaths and DALYs from CRDs were attributed to smoking globally, followed by air pollution and occupational risks. Non-optimal temperature and high body-mass index were additional risk factors for COPD and asthma, respectively. Interpretation: Albeit the age-standardised prevalence, death, and DALYs rates of CRDs have decreased, they still cause a substantial burden and deaths worldwide. The high death and DALYs rates in low and low-middle SDI countries highlights the urgent need for improved preventive, diagnostic, and therapeutic measures. Global strategies for tobacco control, enhancing air quality, reducing occupational hazards, and fostering clean cooking fuels are crucial steps in reducing the burden of CRDs, especially in low- and lower-middle income countries. Funding: Bill & Melinda Gates Foundation
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