33 research outputs found
Statistical Analysis of the Effect of Nanoparticles Volume Fraction on Turbulent Forced Convective Heat Transfer Coefficient of Nanofluid in a Circular Tube
In this paper, the statistical analysis of the effect of nanoparticles volume fraction on one of the most important thermal characteristics turbulent flow of nanofluid i.e. convection heat transfer coefficient, inside a circular tube with uniform wall heat flux is investigated numerically. Also, water as a base fluid and Al2O3 as suspended particles with a diameter of 36 nm are considered. Heat transfer characteristics are computed using the solution of elliptic equations based on discrete the finite volume method and the second order upwind. The relationship between pressure and velocity using SIMPLEC algorithm is established. In this study, the variation of volume fraction of nanoparticles is assumed in the range of 0 to 6%. The best probability distribution function of the heat transfer parameters are selected using chi square test that various probability distribution such as: Gamma, Normal, Lognormal, Gumbel, and Frechet are evaluated based on numerical analysis of tube flow. After reviewing the results, it was found that with increasing volume fraction of nanoparticles, the convective heat transfer coefficient increases. On the other hand, the convective heat transfer coefficients with regard to variation of volume fraction of nanoparticles follow Gumbel Max probability distribution function
Role of Thr399Ile and Asp299Gly polymorphisms of toll-like receptor-4 gene in acute dental abscess
Apical Periodontitis (AP) is an inflammatory disease that affects the tissues surrounding the root end of a tooth. The disease which is caused by endodontic infections presents in different clinical ways including development of an acute abscess. Recent studies have provided information suggesting role of a multitude of factors in pathogenesis of acute apical abscess (AAA). In this case-control study, our goal was to evaluate the frequency and potential role of two common polymorphisms of toll like receptor-4 (TLR-4) gene; Thr399Ile (1196 C>T) and Asp299Gly (+896 A>G), in 50 patients with AAA as cases and 50 patients with asymptomatic apical periodontitis (AAP) as controls.
Saliva sample containing mucosal epithelial cells was used for DNA extraction. Polymorphisms were detected by Tetra-ARMS (Amplification Refractory Mutation System) PCR method. Statistical analyses were carried out in SPSS 21 software.
Homozygous wild type (CC) and heterozygous (CT) genotypes of Thr399Ile polymorphism were detected in 84% and 16% of AAA patients respectively. In controls, respective ratios were 94% (CC) and 6% (CT). Observed difference was not statistically significant (P>0.05) for distribution of these genotypes. The mutant homozygous (TT) genotype of this polymorphism was identified in neither of the participants. Overall, T allele frequency was obtained 8% in AAA and 3% in AAP (OR=2.6, 95% CI; 0. 6-10.6, p>0.05). For Asp299Gly polymorphism, no individual was detected with the mutant allele in case or control groups.
Our results indicated a possible role for Thr399Ile polymorphism in acute presentations of abscess in AAA. However, the impact of this polymorphism needs to be more assessed in future studies
Identify economic indicators (direct and indirect costs) of occupational accidents
The analysis of HSE events, especially occupational accidents, along with identifying the effective factors on the occurrence of accidents is of crucial importance. The study of events before, during and after their occurrence is one of the requirements of study in accidents field. The present study is aimed to manage direct and indirect accident costs and improve the mechanism of accident management based on critical accident costs in the country. The present study is an analytical study that is a cross-sectional case study in different industries of the country. The statistical population of the research includes experts in oil, gas, petrochemical, cement, steel, power plant and road construction and construction, and university professors related to occupational health, industrial safety, HSE, and finally active professors in crisis management and under emergency conditions. 12 people were selected by theoretical saturation method. This research was conducted during 2018 and 2019 in determining the costs of occupational accidents. The research area is in various upstream industries, oil, gas and petrochemical and steel and cement industries and other industrial and urban areas. The research instrument includes a researcher-made questionnaire. Data analysis was performed using fuzzy Delphi method. In the field studies of the study, 8 important and major groups of indicators in occupational accident costs at workplace were identified. In order to calculate and obtain the amount of each of the mentioned indicators, a number of sub- criteria were determined and by examining economic models and calculation software, accident costs and conventional and valid models that had verified validity and reliability showed that 51 sub-indicators in the above 8 groups were effective on calculating the accidents costs. It was found that out of 51 indicators identified in the direct and indirect costs of accidents, 45 indicators have a greater effect and to calculate and technically and economically investigate the accidents costs, 45 indicators were required to be investigated
Grading of Glioma Tumors by Analysis of Minimum Apparent Diffusion Coefficient and Maximum Relative Cerebral Blood Volume
Gliomas are the most common primary neoplasms of the
central nervous system. Relative cerebral blood volume (rCBV) could
estimate high-grade Gliomas computed with dynamic susceptibility contrast
MR imaging which it is artificially lowered by contrast extravasation through
a disrupted blood-brain barrier.
Objectives: Our intent was to clarify the usefulness of diffusion-weighted
magnetic resonance imaging (DWI) and perfusion weighted magnetic
resonance imaging (PWI) in the grading of Gliomas.
Materials and Methods: Both PWI and DWI with a three-tesla scanner
investigated nineteen consecutive patients with Gliomas. The means of rCBV
and ADC values have been compared among the tumor groups with t-test and
ROC curve analysis to determine threshold values of Gliomas grading.
Results: Mean maximum rCBV were 2.71±1.41 for low grades (I & II), and
8.14±2.58 for high grades (III & IV) Gliomas (p=0.001). Mean minimum
ADC were 1.47±.46 ×103 mm2
/s for low grades (I & II), and .47±.38×103
mm2
/s for high grades (III & IV) Gliomas (p=0.001). We can get 0.94×103
mm2
/s for minimum ADC and 3.85 for maximum rCBV as a difference cutoff
point between low and high-grade Gliomas.
Conclusion: Combination of both DWI and PWI techniques, with
measurement of minimum ADC and maximum rCBV can be used to
distinguish between high grade and low-grade Glioma tumors
Geochemistry And Petrology Of Granophyric Granite Veins Penetrated In The Igneous Intrusive Complex In South Of Qorveh Area, West Iran
Abstract: Qorveh area (west Iran) belongs to the Sanandaj-Sirjan zone. Igneous activity resulted from subduction of Neo-Tethys beneath Iran microplate during Mesozoic and Cenozoic produced several intrusive and extrusive rocks throughout Sanandaj-Sirjan zone that convoluted intrusive complex in south of the study area is one of them. This complex is generally comprised of diorite, gabbro, monzonite, quartz-monzonite and quartz-monzodiorite. Several garnophyric granite veins penetrated into the diorite and gabbro in the complex. These granite veins are metaluminous (A/CNK=0.66-0.9), alkalic and have I-type and A-type granitiod geochemical characteristics. These samples have moderate REE contents ( REE=83-147 ppm), negative Eu anomaly (Eu/Eu * =0.4-0.7), high field strength elements (HFSE) Nb, Ta, Ti… contents ( HFSE=70-130 ppm) and high light rare earth elements to heavy rare earth elements (LREE/HREE) ratios (average 6 ppm). Basis on the mineralogical, petrological and geochemical studies, it is clear that crystal plays an important role in generation of this rock. Also, granite samples possess geochemical signatures of active continental margin (enriched in large ion lithophile elements (LILE) Rb, K, U, Sr, Cs and Th with respect to Nb and Ti) and a post-orogenic geodynamic environment
Arg753gln and Arg677 Trp Polymorphisms of Toll-Like Receptor 2 In Acute Apical Abscess
Statement of the Problem: Genetic polymorphisms can alter immunity response against pathogens, which in turn influ-ence individuals’ susceptibility to certain infections.
Purpose: Our aim was to determine the association of Arg753Gln (rs5743708) and Arg677Trp (rs12191786) polymor-phisms of toll like receptor-2 gene with the two clinical forms of apical periodontitis: acute apical abscess (AAA) and asymptomatic apical periodontitis (AAP).
Materials and Method: There were 50 patients with AAA as case group and 50 with AAP as control group. Genotyping was done using Tetra-ARMS (amplification refractory mutation system) PCR.
Results: Heterozygous genotype of Arg677Trp polymorphism was associated with risk of AAA (OR=1.9, 95% CI: 0.7-5.5, p= 0.05). Although statistically insignificant, Arg677Trp polymorphism promoted the risk of AAA in dominant model (OR=2.1, 95% CI: 0.7-5.9, p> 0.05). The frequency of mutant allele (T) of Arg677Trp polymorphism was higher in AAA (14%) than AAP (7%) subjects (OR=1.7, 95% CI: 0.6-4.7). For Arg753Gln polymorphism, wild homozygous (GG) represented the dominant genotype in both cases (96%) and controls (100%). Variant allele (A) of Arg753Gln polymorphism was identified in 2% of AAA, while no individual represented with this allele in AAP subjects. Individuals with Arg753Gln; Arg677Trp (GG; TC) combination showed an elevated risk of AAA (OR=1.6, 95% CI: 0.5- 4.2, p> 0.05).
Conclusion: Arg677Trp polymorphism of TLR-2 rendered a higher risk for the development of abscesses in apical periodontitis. It is recommended to explore role of this polymorphism in other populations
Global age-sex-specific fertility, mortality, healthy life expectancy (HALE), and population estimates in 204 countries and territories, 1950-2019 : a comprehensive demographic analysis for the Global Burden of Disease Study 2019
Background: Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019.
Methods: 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate age-specific fertility rates for 5-year age groups between ages 15 and 49 years. With extensions to age groups 10–14 and 50–54 years, the total fertility rate (TFR) was then aggregated using the estimated age-specific fertility between ages 10 and 54 years. 7417 sources were used for under-5 mortality estimation and 7355 for adult mortality. ST-GPR was used to synthesise data sources after correction for known biases. Adult mortality was measured as the probability of death between ages 15 and 60 years based on vital registration, sample registration, and sibling histories, and was also estimated using ST-GPR. HIV-free life tables were then estimated using estimates of under-5 and adult mortality rates using a relational model life table system created for GBD, which closely tracks observed age-specific mortality rates from complete vital registration when available. Independent estimates of HIV-specific mortality generated by an epidemiological analysis of HIV prevalence surveys and antenatal clinic serosurveillance and other sources were incorporated into the estimates in countries with large epidemics. Annual and single-year age estimates of net migration and population for each country and territory were generated using a Bayesian hierarchical cohort component model that analysed estimated age-specific fertility and mortality rates along with 1250 censuses and 747 population registry years. We classified location-years into seven categories on the basis of the natural rate of increase in population (calculated by subtracting the crude death rate from the crude birth rate) and the net migration rate. We computed healthy life expectancy (HALE) using years lived with disability (YLDs) per capita, life tables, and standard demographic methods. Uncertainty was propagated throughout the demographic estimation process, including fertility, mortality, and population, with 1000 draw-level estimates produced for each metric. Findings: The global TFR decreased from 2·72 (95% uncertainty interval [UI] 2·66–2·79) in 2000 to 2·31 (2·17–2·46) in 2019. Global annual livebirths increased from 134·5 million (131·5–137·8) in 2000 to a peak of 139·6 million (133·0–146·9) in 2016. Global livebirths then declined to 135·3 million (127·2–144·1) in 2019. Of the 204 countries and territories included in this study, in 2019, 102 had a TFR lower than 2·1, which is considered a good approximation of replacement-level fertility. All countries in sub-Saharan Africa had TFRs above replacement level in 2019 and accounted for 27·1% (95% UI 26·4–27·8) of global livebirths. Global life expectancy at birth increased from 67·2 years (95% UI 66·8–67·6) in 2000 to 73·5 years (72·8–74·3) in 2019. The total number of deaths increased from 50·7 million (49·5–51·9) in 2000 to 56·5 million (53·7–59·2) in 2019. Under-5 deaths declined from 9·6 million (9·1–10·3) in 2000 to 5·0 million (4·3–6·0) in 2019. Global population increased by 25·7%, from 6·2 billion (6·0–6·3) in 2000 to 7·7 billion (7·5–8·0) in 2019. In 2019, 34 countries had negative natural rates of increase; in 17 of these, the population declined because immigration was not sufficient to counteract the negative rate of decline. Globally, HALE increased from 58·6 years (56·1–60·8) in 2000 to 63·5 years (60·8–66·1) in 2019. HALE increased in 202 of 204 countries and territories between 2000 and 2019
Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019
Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and injuries, for two sexes, and for 204 countries and territories. Input data were extracted from censuses, household surveys, civil registration and vital statistics, disease registries, health service use, air pollution monitors, satellite imaging, disease notifications, and other sources. Cause-specific death rates and cause fractions were calculated using the Cause of Death Ensemble model and spatiotemporal Gaussian process regression. Cause-specific deaths were adjusted to match the total all-cause deaths calculated as part of the GBD population, fertility, and mortality estimates. Deaths were multiplied by standard life expectancy at each age to calculate YLLs. A Bayesian meta-regression modelling tool, DisMod-MR 2.1, was used to ensure consistency between incidence, prevalence, remission, excess mortality, and cause-specific mortality for most causes. Prevalence estimates were multiplied by disability weights for mutually exclusive sequelae of diseases and injuries to calculate YLDs. We considered results in the context of the Socio-demographic Index (SDI), a composite indicator of income per capita, years of schooling, and fertility rate in females younger than 25 years. Uncertainty intervals (UIs) were generated for every metric using the 25th and 975th ordered 1000 draw values of the posterior distribution. Findings: Global health has steadily improved over the past 30 years as measured by age-standardised DALY rates. After taking into account population growth and ageing, the absolute number of DALYs has remained stable. Since 2010, the pace of decline in global age-standardised DALY rates has accelerated in age groups younger than 50 years compared with the 1990–2010 time period, with the greatest annualised rate of decline occurring in the 0–9-year age group. Six infectious diseases were among the top ten causes of DALYs in children younger than 10 years in 2019: lower respiratory infections (ranked second), diarrhoeal diseases (third), malaria (fifth), meningitis (sixth), whooping cough (ninth), and sexually transmitted infections (which, in this age group, is fully accounted for by congenital syphilis; ranked tenth). In adolescents aged 10–24 years, three injury causes were among the top causes of DALYs: road injuries (ranked first), self-harm (third), and interpersonal violence (fifth). Five of the causes that were in the top ten for ages 10–24 years were also in the top ten in the 25–49-year age group: road injuries (ranked first), HIV/AIDS (second), low back pain (fourth), headache disorders (fifth), and depressive disorders (sixth). In 2019, ischaemic heart disease and stroke were the top-ranked causes of DALYs in both the 50–74-year and 75-years-and-older age groups. Since 1990, there has been a marked shift towards a greater proportion of burden due to YLDs from non-communicable diseases and injuries. In 2019, there were 11 countries where non-communicable disease and injury YLDs constituted more than half of all disease burden. Decreases in age-standardised DALY rates have accelerated over the past decade in countries at the lower end of the SDI range, while improvements have started to stagnate or even reverse in countries with higher SDI. Interpretation: As disability becomes an increasingly large component of disease burden and a larger component of health expenditure, greater research and developm nt investment is needed to identify new, more effective intervention strategies. With a rapidly ageing global population, the demands on health services to deal with disabling outcomes, which increase with age, will require policy makers to anticipate these changes. The mix of universal and more geographically specific influences on health reinforces the need for regular reporting on population health in detail and by underlying cause to help decision makers to identify success stories of disease control to emulate, as well as opportunities to improve. Funding: Bill & Melinda Gates Foundation. © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licens
Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
A double burden of malnutrition occurs when individuals, household members or communities experience both undernutrition and overweight. Here, we show geospatial estimates of overweight and wasting prevalence among children under 5 years of age in 105 low- and middle-income countries (LMICs) from 2000 to 2017 and aggregate these to policy-relevant administrative units. Wasting decreased overall across LMICs between 2000 and 2017, from 8.4% (62.3 (55.1–70.8) million) to 6.4% (58.3 (47.6–70.7) million), but is predicted to remain above the World Health Organization’s Global Nutrition Target of <5% in over half of LMICs by 2025. Prevalence of overweight increased from 5.2% (30 (22.8–38.5) million) in 2000 to 6.0% (55.5 (44.8–67.9) million) children aged under 5 years in 2017. Areas most affected by double burden of malnutrition were located in Indonesia, Thailand, southeastern China, Botswana, Cameroon and central Nigeria. Our estimates provide a new perspective to researchers, policy makers and public health agencies in their efforts to address this global childhood syndemic
Competition in the American Mutual Fund Industry. An empirical study
This thesis investigates and compares the relationship between the inflow of new investment into open-end equity U.S. mutual funds and their historical performance among the top performer funds. Using a piecewise linear regression and applying the Fama and MacBeth (1973) two stages estimation method on the fund data over the period between January 2004 and December 2014, it was found that the level of convexity within top performer is more extreme than what is usually observed as a convexity in the flow-performance relation among the whole industry players. The difference is irrespective of the performance measurement and is both statistically and economically significant. The results obtained suggest that the competition among the mutual funds is not just about being better than average but is rather about winning the “competition”. Fund managers can achieve marked additional inflow related to their peers by securing their position among top 10% of the industry in terms of performance. A positive significant relation between Morningstar rating and fund flow, was also documented