409 research outputs found

    Performance study of the multiwavelet discontinuous Galerkin approach for solving the Green‐Naghdi equations

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    This paper presents a multiresolution discontinuous Galerkin scheme for the adaptive solution of Boussinesq‐type equations. The model combines multiwavelet‐based grid adaptation with a discontinuous Galerkin (DG) solver based on the system of fully nonlinear and weakly dispersive Green‐Naghdi (GN) equations. The key feature of the adaptation procedure is to conduct a multiresolution analysis using multiwavelets on a hierarchy of nested grids to improve the efficiency of the reference DG scheme on a uniform grid by computing on a locally refined adapted grid. This way the local resolution level will be determined by manipulating multiwavelet coefficients controlled by a single user‐defined threshold value. The proposed adaptive multiwavelet discontinuous Galerkin solver for GN equations (MWDG‐GN) is assessed using several benchmark problems related to wave propagation and transformation in nearshore areas. The numerical results demonstrate that the proposed scheme retains the accuracy of the reference scheme, while significantly reducing the computational cost

    Suicide Attempts in Ilam Province, West of Iran, 2010-2014: A Time Trend Study

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    Background: Suicide has become an increasingly widespread form of morbidity in the developing countries. There has been an increasing trend in morbidity and mortality due to suicide in Iran over the past few decades. This study surveyed attempts and completed suicide over a 5-year period. Methods: Through a cross-sectional study, overall identified suicides by systematic registration suicide data (SRSD) in Ilam Province, western Iran from 21 March 2010 to 11 December 2014 were enrolled. Multiple logistic regression analysis was used for measuring the association between the risk factors of interest and suicide. The statistical software package was Stata 11.2. Results: A Suicide attempts have slightly increased in Ilam during 2010-2014, during which, 6,818 attempted suicides occurred of which 546 were completed. The odds of completed suicide was higher among older age groups than younger ones so that the crude OR estimates of completed suicide among people aged 50 to 59 yr against people aged <20 yr was (OR=6.99; 95 CI: 3.02, 11.07). The crude and adjusted odds ratio (OR) estimates of completed suicide in males against females were (OR=3.22; 95 CI: 2.58, 3.93) and (OR=3.66; 95 CI: 3.03, 4.11), respectively. Significant excess risk also appeared with academic against illiterate attempters (OR= 2.31; 95 CI: 1.35, 3.95). Results showed no increasing trend in the suicide method. Some methods such as self-immolation had decreasing trend over time, although it was not statistically significant (P= 0.089). Conclusions: We observed the variety of suicide risk factors that calls for more diversity in preventative programs. Distribution of suicide methods is diverse across the period of the study

    Trends in 5-, 10-, 20-, and 30-year survival rates of beta-thalassemia patients in Southern Iran, 1995-2016: A retrospective cohort study

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    Background: There is currently lack of knowledge about survival trend analysis of thalassemia patients. Therefore, the aim of the present study was to assess 5-, 10-, 20-, and 30-year survival of thalassemia patients over a 20- year time period. Methods: In this retrospective cohort study, we analysed the data of 982 beta-thalassemia patients in Iran. Birth cohort and traditional cohort analyses were used to obtain the 5-, 10-, 20-, and 30-year survival rates in various time intervals between 1995 and 2016. Results: Five and 10-year survival rates remained unchanged since 1995-2016. Overall, 20- and 30-year survival rates were lower in younger birth cohorts than older ones. A declining trend was found in 20-year survival rate from 1995 to 2000 for all and also for thalassemia major patients, but was stable from 2001 to 2016. In addition, there was a declining trend in 30-year survival rate from 1995 to 2008 for all and also for thalassemia major patients, but was an increased trend from 2009 to 2016. Conclusion: Over the past two decades and in recent birth cohorts, the 20- and 30-year survival rates has declined. In other words, declining survival trends in the birth cohorts may be associated with some different causes of mortality such as exposure to the toxic effects of iron over time and the occurrence of disease-related mortality

    A discontinuous Galerkin approach for conservative modelling of fully nonlinear and weakly dispersive wave transformations

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    This work extends a robust second-order Runge-Kutta Discontinuous Galerkin (RKDG2) method to solve the fully nonlinear and weakly dispersive flows, within a scope to simultaneously address accuracy, conservativeness, cost-efficiency and practical needs. The mathematical model governing such flows is based on a variant form of the Green-Naghdi (GN) equations decomposed as a hyperbolic shallow water system with an elliptic source term. Practical features of relevance (i.e. conservative modelling over irregular terrain with wetting and drying and local slope limiting) have been restored from an RKDG2 solver to the Nonlinear Shallow Water (NSW) equations, alongside new considerations to integrate elliptic source terms (i.e. via a fourth-order local discretization of the topography) and to enable local capturing of breaking waves (i.e. via adding a detector for switching off the dispersive terms). Numerical results are presented, demonstrating the overall capability of the proposed approach in achieving realistic prediction of nearshore wave processes involving both nonlinearity and dispersion effects within a single model

    Hyperglycemia decreased medial amygdala projections to medial Preoptic area in experimental model of diabetes mellitus

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    In Wistar rats, reproductive behavior is controlled in a neural circuit of ventral forebrain including the medial amygdala (Me), bed nucleus of the stria terminalis (BNST) and medial preoptic area (MPOA) via perception of social odors. Diabetes Mellitus (DM) is a widespread metabolic disease that affects many organs in a variety of levels. DM can cause central neuropathies such as neuronal apoptosis, dendritic atrophy, neurochemical alterations and also causes reproductive dysfunctions. So we hypothesized damage to the nuclei of this circuit can cause reproductive dysfunctions. Therefore in this project we assessed diabetic effect on these nuclei. For this purpose neuron tracing technique and TUNEL assay were used. We injected HRP in the MPOA and counted labeled cells in the Me and BNST to evaluate the reduction of neurons in diabetic animals. Also, coronal sections were analyzed with the TMB histochemistry method. Animals in this study were adult male Wistar rats (230 ± 8g) divided to control and 10-week streptozotocin-induced diabetic groups. After data analysis by SPSS 16 software, a significant reduction of HRP-labeled neurons was shown in both Me and BNST nuclei in the diabetic group. Moreover, apoptotic cells were significantly observed in diabetic animals in contrast to control the group. In conclusion, these alterations of the circuit as a result of diabetes might be one of the reasons for reproductive dysfunctions. © 2015 Tehran University of Medical Sciences. All rights reserved

    A chemiluminescent method for the detection of H 2 O 2 and glucose based on intrinsic peroxidase-like activity of WS 2 quantum dots

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    Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS 2 quantum dots (WS 2 QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS 2 QDs with a size of 1�1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS 2 QDs with uniform morphology showed a high catalytic effect in destroying H 2 O 2 . The peroxidase-like activity of synthesized nanostructures was studied in H 2 O 2 chemical and electrochemical reduction systems. The mimetic effect of WS 2 QDs was also shown in an H 2 O 2 �rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H 2 O 2 is one of the products which can be determined. Under optimum conditions, H 2 O 2 can be detected in the concentration range of 0�1000 nmol·L � 1 , with a detection limit of 2.4 nmol·L � 1 . Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01�30 nmol·L � 1 , with a limit of detection (3S) of 4.2 nmol·L � 1 © 2019 by the authors

    High-sensitive troponin I and re-hospitalization in patients with decompensated congestive heart failure

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    Patients with heart failure (HF) are frequently admitted for episodes of decompensation. Cardiac troponins are easily accessible biomarkers role of which for risk stratification of re-hospitalization among HF patients is less certain. We aimed to evaluate high-sensitive cardiac troponin I (hs-cTnI) levels among re-hospitalized patients with decompensated heart failure (D-HF). Consecutive subjects admitted with D-HF to 2 hospitals in Tehran, during the year 2014 were recruited. Excluded ones were patients with a suspected acute coronary syndrome or myocarditis/pericarditis, those with cardiopulmonary resuscitation/DC shock delivery, or major complications during or after hospitalization. Along with echocardiography parameters, level of hs-cTnI was checked at the first hour of hospitalization and 3 months after discharge. The patients were then categorized according to having or not having re-hospitalization during 3 months post discharge. A total of 97 patients were finally recruited. Among re-hospitalized patients, Left ventricular (LV) ejection fraction was significantly lower (38±14 vs. 50 ± 12; P=0.001), and LV end-systolic dimension was significantly higher (44±9 mm vs. 38±11 mm; P=0.012) compared to the other group. Moreover, levels of hs-cTnI were significantly higher among the re-hospitalized patients, both at initial visit (0.66±0.43 ng/ml vs 0.51±0.14 ng/ml, respectively; P=0.017) and at 3 months (0.59±0.48 ng/ml vs 0.48±0.23 ng/ml, respectively; P=0.030). This prospective study demonstrated that levels of hs-cTnI (both at the base and at follow up) are higher among patients who readmitted during 3 months of hospitalization for D-HF. © 2019 Tehran University of Medical Sciences. All rights reserved

    A Chemiluminescent Method for the Detection of H�O� and Glucose Based on Intrinsic Peroxidase-Like Activity of WS� Quantum Dots

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    Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS� quantum dots (WS� QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS� QDs with a size of 1�1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS� QDs with uniform morphology showed a high catalytic effect in destroying H�O�. The peroxidase-like activity of synthesized nanostructures was studied in H�O� chemical and electrochemical reduction systems. The mimetic effect of WS� QDs was also shown in an H�O��rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H�O� is one of the products which can be determined. Under optimum conditions, H�O� can be detected in the concentration range of 0�1000 nmol·L-1, with a detection limit of 2.4 nmol·L-1. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01�30 nmol·L-1, with a limit of detection (3S) of 4.2 nmol·L-1

    Occupational cognitive failure and its relationship with unsafe behaviors and accidents

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    Objectives. The aim of this study was to assess the relationship between occupational cognitive failures (OCFs) and unsafe behaviors, accidents and driving offences among municipal bus drivers in Tehran, Iran. Methods. Systematic random sampling was used to select 190 drivers from 3 transport and traffic Tehran districts. Data were collected with the occupational cognitive failure questionnaire (OCFQ), the driver behavior questionnaire and a data collection form. Results. The mean (SD) numbers of driving-related offences and road traffic accidents were 1.5 (2.6) and 0.37 (1.0), respectively. The mean (SD) numbers of deliberate driving violations, unintended violations, driving slips and mistakes were 6.97 (5.5), 1.61 (1.5), 13.6 (9.0) and 4.53 (3.28), respectively. The mean (SD) number of the OCFs was 28.9 (20.5). A significant correlation was found between occupational cognitive error and unsafe driving behavior subscales. The stepwise logistic regression results showed that, while controlling the effects of confounding factors, the OCF predicts 6, 9, 15 and 9 of deliberate violations, unintended violations, driving slips and driving mistakes, respectively. Conclusion. The results of this study show that the score of the OCFQ is a predictor of unsafe driving behaviors and its subscales

    Factors influencing unsafe behaviors and accidents on construction sites: A review

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    Objective. Construction is a hazardous occupation due to the unique nature of activities involved and the repetitiveness of several field behaviors. The aim of this methodological and theoretical review is to explore the empirical factors influencing unsafe behaviors and accidents on construction sites. Methods. In this work, results and findings from 56 related previous studies were investigated. These studies were categorized based on their design, type, methods of data collection, analytical methods, variables, and key findings. A qualitative content analysis procedure was used to extract variables, themes, and factors. In addition, all studies were reviewed to determine the quality rating and to evaluate the strength of provided evidence. Results. The content analysis identified 8 main categories: (a) society, (b) organization, (c) project management, (d) supervision, (e) contractor, (f) site condition, (g) work group, and (h) individual characteristics. The review highlighted the importance of more distal factors, e.g., society and organization, and project management, that may contribute to reducing the likelihood of unsafe behaviors and accidents through the promotion of site condition and individual features (as proximal factors). Conclusion. Further research is necessary to provide a better understanding of the links between unsafe behavior theories and empirical findings, challenge theoretical assumptions, develop new applied theories, and make stronger recommendations
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