290 research outputs found
Damage Probability Matrices and Empirical Fragility Curves From Damage Data on Masonry Buildings After Sarpol-e-zahab and Bam Earthquakes of Iran
The weakness of tensile strength and high weight in masonry structures under the dynamic loads of earthquakes has always led to structural damage, financial losses, injuries, and deaths. In spite of cheap and affordable masonry materials, their use has been very limited in constructions over the past three decades. However, common masonry materials are still found in monumental and historical structures, deteriorated texture, and rural buildings. Identifying the seismic behavior and the probability of the structural damage is vital for pre-earthquake seismic risk reduction of urban areas and the rapid post-earthquake assessment. The earthquake event that occurred in Ezgeleh on 2017 November 12 with Mw = 7.3 triggered the greatest damage in Sarpol-e-zahab city at a distance of about 37 km from the epicenter. Post-earthquake reconnaissance, microtremor analysis, and rapid visual inventory of structural damages in different zones were performed by research teams. In the present study, the strong ground motion and the peak ground acceleration, and its corresponding intensity distribution, which are based on the site response analysis in different parts of the city, are introduced. Afterward, damage probability matrices of different types of masonry buildings, namely unreinforced masonry and confined masonry buildings, are determined for both bins of peak ground accelerations and intensities. Finally, the fragility curves of two types of masonry structures are extracted based on the RISK-UE level 1 (LM1) method by assuming a beta distribution to estimate the probability distribution function of the damage. These curves are useful in assessing pre-earthquake possible damages in masonry structures with similar construction methods and similar materials to reduce seismic risks
Validation of the persian version of spiritual well-being questionnaires
Background: Spiritual well-being is an important issue in health sciences, hence the need for validated instruments to assess this aspect of health in the Iranian population. The aim of the current study was to determine the validity of the Persian versions of 2 most common measures of spiritual health (Spiritual Well-Being Questionnaire SWBQ or Spiritual Health and Life-Orientation Measure SHALOM and Spiritual Well-Being Scale SWBS). Methods: This was a cross-sectional study via a convenience sampling method in Iran University of Medical Sciences with 170 participants aged above 18 years comprising students, teachers, and administrative staff and managers. The study was conducted from September 7, 2014 to September 20, 2015 in Tehran. Four questionnaires, namely the SWBQ, SWBS, General Health Questionnaire (GHQ-12), and Oxford Happiness Questionnaire (OHQ), were used. Statistical analysis was done using SPSS 18 and LISREL (version 8.2). Cronbach�s alpha, intra-class correlation coefficient, Pearson correlation, and confirmatory factor analysis were employed to assess the validity and reliability of the questionnaires. Results: Cronbach�s alpha for the SWBQ and the SWBS was greater than 0.85. The repeatability of both questionnaires was between 0.88 and 0.98. The Pearson correlation for the SWBQ and the SWBS ranged from 0.33 to 0.53; and all the correlations were significant. The respondents who indicated a higher spiritual well-being also reported better general health and happiness. Conclusion: The Persian versions of the SWBS and the SWBQ have good reliability, repeatability, and validity to assess spiritual health in the Iranian population. © 2018, Shiraz University of Medical Sciences. All rights reserved
Validation of the persian version of spiritual well-being questionnaires
Background: Spiritual well-being is an important issue in health sciences, hence the need for validated instruments to assess this aspect of health in the Iranian population. The aim of the current study was to determine the validity of the Persian versions of 2 most common measures of spiritual health (Spiritual Well-Being Questionnaire SWBQ or Spiritual Health and Life-Orientation Measure SHALOM and Spiritual Well-Being Scale SWBS). Methods: This was a cross-sectional study via a convenience sampling method in Iran University of Medical Sciences with 170 participants aged above 18 years comprising students, teachers, and administrative staff and managers. The study was conducted from September 7, 2014 to September 20, 2015 in Tehran. Four questionnaires, namely the SWBQ, SWBS, General Health Questionnaire (GHQ-12), and Oxford Happiness Questionnaire (OHQ), were used. Statistical analysis was done using SPSS 18 and LISREL (version 8.2). Cronbach�s alpha, intra-class correlation coefficient, Pearson correlation, and confirmatory factor analysis were employed to assess the validity and reliability of the questionnaires. Results: Cronbach�s alpha for the SWBQ and the SWBS was greater than 0.85. The repeatability of both questionnaires was between 0.88 and 0.98. The Pearson correlation for the SWBQ and the SWBS ranged from 0.33 to 0.53; and all the correlations were significant. The respondents who indicated a higher spiritual well-being also reported better general health and happiness. Conclusion: The Persian versions of the SWBS and the SWBQ have good reliability, repeatability, and validity to assess spiritual health in the Iranian population. © 2018, Shiraz University of Medical Sciences. All rights reserved
Experimental and numerical investigation of the weld geometry effects on Type IV cracking behaviour in P91 steel
The focus of the present study is on creep crack growth behaviour in Type IV region of P91 steel weldments at 650 °C. In the experimental studies on small- and large-scale single-edge notched specimens in tension, SENT, the effects of weld dimensions and specimen size on the creep crack growth behaviour of the material are investigated. The experimental results demonstrate that the crack starts to propagate at an angle normal to the loading direction, subsequently deviates towards the Type IV region and the specimen eventually ruptures when the crack growth angle becomes parallel to the loading direction. The creep rupture data for SENT specimens compared well with those of the round bar specimens for P91 welded joints. In addition, the data for crack growth rates from the deviating crack path were correlated with the C* fracture mechanics parameter and showed good agreement with standard compact tension test data. To predict the creep crack growth behaviour in the Type IV region, finite element simulations were performed in conjunction with a multiaxial ductility damage criterion at the weld/base metal interface. Given that a lower failure strain along the Type IV region is prominent, it is shown that the cracking, in line with the experiments, followed the HAZ region and led to the final creep rupture in the net sectio
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Evaluation of coronary stents: a review of types, materials, processing techniques, design, and problems
In the world, one of the leading causes of death is coronary artery disease (CAD). There are several ways to treat this disease, and stenting is currently the most appropriate way in many cases. Nowadays, the use of stents has rapidly increased, and they have been introduced in various models, with different geometries and materials. To select the most appropriate stent required, it is necessary to have an analysis of the mechanical behavior of various types of stents. The purpose of this article is to provide a complete overview of advanced research in the field of stents and to discuss and conclude important studies on different topics in the field of stents. In this review, we introduce the types of coronary stents, materials, stent processing technique, stent design, classification of stents based on the mechanism of expansion, and problems and complications of stents. In this article, by reviewing the biomechanical studies conducted in this field and collecting and classifying their results, a useful set of information has been presented to continue research in the direction of designing and manufacturing more efficient stents, although the clinical-engineering field still needs to continue research to optimize the design and construction. The optimum design of stents in the future is possible by simulation and using numerical methods and adequate knowledge of stent and artery biomechanics
The effects of filamentary Ni, graphene and lithium amide (LiNH2) additives on the dehydrogenation behavior of mechano-chemically synthesized crystalline manganese borohydride (Mn(BH4)2) and its solvent filtration/extraction
The final publication is available at Elsevier via http:/dx.doi.org/10.1016/j.materresbull.2017.12.051 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Dehydrogenation properties of mechano-chemically synthesized crystalline Mn(BH4)2 hydride without and with ultrafine filamentary carbonyl nickel (Ni), graphene and LiNH2 were investigated. It is reported for the first time that all additives suppressed the release of B2H6 with the filamentary Ni additive being the most effective suppressor of B2H6. In DSC, the decomposition peak of Mn(BH4)2 was endothermic. The estimated apparent activation energy for isothermal dehydrogenation was dramatically reduced to 44.9 ± 4.3 kJ/mol for the 5 wt.% LiNH2 additive from about 76–81 kJ/mol range for the additive-free sample and 5 wt.% filamentary Ni and graphene additives. The most striking finding, that has never been reported in the literature, is that the process of solvent filtration and extraction of the mechano-chemically synthesized (Mn(BH4)2/LiCl) sample, resulted in the crystallization of a dimetallic borohydride solvate [{Li(Et2O)2}Mn2(BH4)5] instead of crystalline Mn(BH4)2. Its dehydrogenation behavior was investigated isothermally and by TGA/DSC.Natural Sciences and Engineering Research Council (NSERC) of Canada Discovery gran
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Persistence of earnings and prediction of future cash flows: the role of timely recognition of bad news
Timely recognition of losses and expenses compared to revenues and increased values precipitates future expenses to match with current revenues. Thus, timely recognition of losses acts to reduce the persistence of earnings. However, it is expected that a more timely recognition of negative cash flows, as bad news, increase the power of earnings for predicting future cash flows. This study investigates the effects of the timely recognition of bad news (loss) versus the good news on the decrease of the persistence of earnings, and the effect of negative cash flows on forecasting future cash flows. In this study, two pooling type models and a panel type model have been used to estimate the persistence of earnings and cash flows. Seventy eight firms that were listed in the Tehran Stock Exchange during the period 2003–2010 were duly reviewed. The results of this research proved that the timely recognition of loss does not affect the persistence and the power of earnings for the purpose of forecasting future cash flows. The findings imply that conservatism does not distort persistence of earnings
Mosaic trisomy 22 in a 4-year-old boy with congenital heart disease and general hypotrophy: A case report
Background: Trisomy 22 mosaicism is a rare autosomal anomaly with survival compatibility. Recognition of the complete trisomy 22 which is incompatible with life from the mosaic form is critical for genetic counseling. Affected mosaic cases have prevalent clinical presentations such as webbed neck, developmental delay, abnormal ears, cardiac disorders, and microcephaly. Phenotype of these patients is milder than full chromosomal aneuploidy, and the severity of the phenotype depends on the count of trisomic cells. We describe a 4-year-old boy with mosaic trisomy 22 from healthy parents and no family history of any genetic disorders in the pedigree. Method and Results: The patient had determined dysmorphic clinical features including facial asymmetry, cleft palate, gastroenteritis, hydronephrosis, developmental delay, genital anomalies, dysplastic toenails, flattened nasal bridge, congenital heart defect, hearing loss, cryptorchidism, and hypotonic muscle. He is the first reported with hypothyroidism and larynx wall thickness in worldwide and the first with atrial septal defect (ASD) from Iran. Chromosomal analyses using G-banding indicated a de novo Mos 47,XY,+22(6)/46,XY(44) karyotype with no other chromosomal structural changes. Conclusions: Our observations confirm the importance of cytogenetic analyses for determining the cause of congenital anomalies and provide a useful genetic counseling. In addition, due to the fact that some of mosaic trisomy 22 features are unavoidable such as CHD and general hypotrophy, we suggest including echocardiography test for early diagnosis during the clinical assessment. © 2018 Wiley Periodicals, Inc
CerS6-dependent ceramide synthesis in hypothalamic neurons promotes ER/mitochondrial stress and impairs glucose homeostasis in obese mice
Dysregulation of hypothalamic ceramides has been associated with disrupted neuronal pathways in control of energy and glucose homeostasis. However, the specific ceramide species promoting neuronal lipotoxicity in obesity have remained obscure. Here, we find increased expression of the C ceramide-producing ceramide synthase (CerS)6 in cultured hypothalamic neurons exposed to palmitate in vitro and in the hypothalamus of obese mice. Conditional deletion of CerS6 in hypothalamic neurons attenuates high-fat diet (HFD)-dependent weight gain and improves glucose metabolism. Specifically, CerS6 deficiency in neurons expressing pro-opiomelanocortin (POMC) or steroidogenic factor 1 (SF-1) alters feeding behavior and alleviates the adverse metabolic effects of HFD feeding on insulin sensitivity and glucose tolerance. POMC-expressing cell-selective deletion of CerS6 prevents the diet-induced alterations of mitochondrial morphology and improves cellular leptin sensitivity. Our experiments reveal functions of CerS6-derived ceramides in hypothalamic lipotoxicity, altered mitochondrial dynamics, and ER/mitochondrial stress in the deregulation of food intake and glucose metabolism in obesity
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The ability of analysts’ recommendations to predict optimistic and pessimistic forecasts
Previous researches show that buy (growth) companies conduct income increasing earnings management in order to meet forecasts and generate positive forecast Errors (FEs). This behavior however, is not inherent in sell (non-growth) companies. Using the aforementioned background, this research hypothesizes that since sell companies are pressured to avoid income increasing earnings management, they are capable, and in fact more inclined, to pursue income decreasing Forecast Management (FM) with the purpose of generating positive FEs. Using a sample of 6553 firm-years of companies that are listed in the NYSE between the years 2005–2010, the study determines that sell companies conduct income decreasing FM to generate positive FEs. However, the frequency of positive FEs of sell companies does not exceed that of buy companies. Using the efficiency perspective, the study suggests that even though buy and sell companies have immense motivation in avoiding negative FEs, they exploit different but efficient strategies, respectively, in order to meet forecasts. Furthermore, the findings illuminated the complexities behind informative and opportunistic forecasts that falls under the efficiency
versus opportunistic theories in literature
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