Investigating the role of temperature on thermal stress and fracture propagation in geothermal systems

Available geothermal energy extractable by conventional techniques is in dry and comparatively impermeable rocks. Enhanced Geothermal System (EGS) technologies enhance geothermal resources in the hot dry rock (HDR) through fracture operations, usually through hydro-shearing. Large scale deployment of geothermal power production requires the demonstration of successful EGS projects extracting heat from reservoirs constituting a variety of geological conditions. In this part, numerical models are very important to show how geothermal power plant operations can be less risky and safer. Owing the fact that, some major challenges in these operations are interaction between shear and tensile fractures with natural faults. These interactions can be seen in two different cases, either these faults are badly oriented or these faults are fill in pore fluids or gases which are mainly high pressure. Fluids and gases are important on account for because of the fact that these pore fluids can over whelmed the injection pressure and cause well blow out. Furthermore, to prevent these operational hazards, we use field data and analysis in combination with experimental tests and numerical/analytical models with finite element method software such as COMSOL Multiphysics. Further work will be required for improving enhanced geothermal production by optimizing hydro-shearing practices

Prevalence of chronic kidney disease and its associated risk factors: The first report from Iran using both microalbuminuria and urine sediment

Background: The incidence of major risk factors of chronic kidney disease (CKD) in the world is on the rise, and it is expected that this incidence and prevalence, particularly in developing countries, will continue to increase. Using data on urinary sediment and microalbuminuria, we aimed to estimate the prevalence of CKD in northeast Iran. Methods: In a cross-sectional study, the prevalence of CKD in a sample of 1557 regionally representative people, aged � 18 years, was analyzed. CKD was determined based on glomerular filtration rate (GFR) and microalbuminuria. Life style data, urine and blood samples were collected. Urine samples without any proteinuria in the initial dipstick test were checked for qualitative microalbuminuria. If the latter was positive, quantitative microalbuminuria was evaluated. Results: 1557 subjects with a mean age of 56.76 ± 12.04 years were enrolled in this study. Based on the modifcation of diet in renal disease (MDRD) equation, 137 subjects (8.89%) were categorized as CKD stages III-V. Based on urine abnormalities, the prevalence of combined CKD stages I and II was 10.63%, and based on macro- and microalbuminuria it was 14.53%. The prevalence of CKD was significantly associated with sex, age, marital status, education, diabetes mellitus (DM), hypertension (HTN), ischemic heart disease (IHD), waist to hip ratio, myocardial infarction (MI), and cerebrovascular accident (CVA). Conclusion: CKD and its main risk factors are common and represent a definite health threat in this region of Iran. Using and standardizing less expensive screening tests in low resource countries could be a good alternative that may improve the outcome through early detection of CKD

Metabolic risk factors and risk of Covid-19: A systematic review and meta-analysis

Objective Based on the epidemiologic findings of Covid-19 incidence; illness and mortality seem to be associated with metabolic risk factors. This systematic review and meta-analysis aimed to assess the association of metabolic risk factors and risk of Covid-19. Methods This study was designed according to PRISMA guidelines. Two independent researchers searched for the relevant studies using PubMed, Web of Science, Cochrane Library, and Scopus. The search terms developed focusing on two main roots of "Covid-19"and "metabolic risk factors". All relevant observational, analytical studies, review articles, and a meta-analysis on the adult population were included in this meta-analysis. Meta-analysis was performed using the random effect model for pooling proportions to address heterogeneity among studies. Data were analyzed using STATA package version 11.2, (Stata- Corp, USA). Results Through a comprehensive systematic search in the targeted databases we found 1124 papers, after running the proses of refining, 13 studies were included in the present meta-analysis. The pooled prevalence of obesity in Covid-19 patients was 29 (95 CI: 14-47). For Diabetes and Hypertension, these were 22 (95 CI: 12 33) and 32 (95 CI: 12 56), respectively. There was significant heterogeneity in the estimates of the three pooled prevalence without any significant small-study effects. Such warning points, to some extent, guide physicians and clinicians to better understand the importance of controlling co-morbid risk factors in prioritizing resource allocation and interventions. Conclusion The meta-analysis showed that hypertension is more prevalent than obesity and diabetes in patients with Covid-19 disease. The prevalence of co-morbid metabolic risk factors must be adopted for better management and priority settings of public health vaccination and other required interventions. The results may help to improve services delivery in COVID-19 patients, while helping to develop better policies for prevention and response to COVID-19 and its critical outcomes. © 2020 Moazzami et al

The role of hemodialysis machines dedication in reducing Hepatitis C transmission in the dialysis setting in Iran: A multicenter prospective interventional study

BACKGROUND: Hepatitis C virus (HCV) infection is a significant problem among patients undergoing maintenance hemodialysis (HD). We conducted a prospective multi-center study to evaluate the effect of dialysis machine separation on the spread of HCV infection. METHODS: Twelve randomly selected dialysis centers in Tehran, Iran were randomly divided into two groups; those using dedicated machines (D) for HCV infected individuals and those using non-dedicated HD machines (ND). 593 HD cases including 51 HCV positive (RT-PCR) cases and 542 HCV negative patients were enrolled in this study. The prevalence of HCV infection in the D group was 10.1% (range: 4.6%– 13.2%) and it was 7.1% (range: 4.2%–16.8%) in the ND group. During the study conduction 5 new HCV positive cases and 169 new HCV negative cases were added. In the D group, PCR positive patients were dialyzed on dedicated machines. In the ND group all patients shared the same machines. RESULTS: In the first follow-up period, the incidence of HCV infection was 1.6% and 4.7% in the D and ND group respectively (p = 0.05). In the second follow-up period, the incidence of HCV infection was 1.3% in the D group and 5.7% in the ND group (p < 0.05). CONCLUSIONS: In this study the incidence of HCV in HD patients decreased by the use of dedicated HD machines for HCV infected patients. Additional studies may help to clarify the role of machine dedication in conjunction with application of universal precautions in reducing HCV transmission

Dental caries in primary and permanent teeth in children's worldwide, 1995 to 2019: a systematic review and meta-analysis

Background: Early childhood caries (ECC) is a type of dental caries in the teeth of infants and children that is represented as one of the most prevalent dental problems in this period. Various studies have reported different types of prevalence of dental caries in primary and permanent teeth in children worldwide. However, there has been no comprehensive study to summarize the results of these studies in general, so this study aimed to determine the prevalence of dental caries in primary and permanent teeth in children in different continents of the world during a systematic review and meta-analysis. Methods: In this review study, articles were extracted by searching in the national and international databases of SID, MagIran, IranMedex, IranDoc, Cochrane, Embase, ScienceDirect, Scopus, PubMed, and Web of Science (ISI) between 1995 and December 2019. Random effects model was used for analysis and heterogeneity of studies was evaluated by using the I2 index. Data were analyzed by using the Comprehensive Meta-Analysis (Version 2) software. Findings: In this study, a total of 164 articles (81 articles on the prevalence of dental caries in primary teeth and 83 articles on the prevalence of dental caries in permanent teeth) were entered the meta-analysis. The prevalence of dental caries in primary teeth in children in the world with a sample size of 80,405 was 46.2% (95% CI: 41.6–50.8%), and the prevalence of dental caries in permanent teeth in children in the world with a sample size of 1,454,871 was 53.8% (95% CI: 50–57.5%). Regarding the heterogeneity on the basis of meta-regression analysis, there was a significant difference in the prevalence of dental caries in primary and permanent teeth in children in different continents of the world. With increasing the sample size and the year of study, dental caries in primary teeth increased and in permanent teeth decreased. Conclusion: The results of this study showed that the prevalence of primary and permanent dental caries in children in the world was found to be high. Therefore, appropriate strategies should be implemented to improve the aforementioned situation and to troubleshoot and monitor at all levels by providing feedback to hospitals

Travel for transplantation in Iran: Pros and cons regarding Iranian model

Transplant tourism is one of the main unacceptable aspects of medical tourism, implicating travel to another country to receive an allograft. Organ shortages in wealthier countries have persuaded patients to preclude organ waiting lists and travel to other countries for getting organs especially kidneys. On the other hand, in many countries, there is no transplant program, and hemodialysis is expensive. Hence, patients with end-stage kidney disease may have to travel to get a kidney allograft for the sake of their lives. In Iran, a legal compensated and regulated living unrelated donor kidney transplant program has been adopted since 1988, in which recipients are matched with liveunrelated donors through the Iran Kidney Foundation and the recipients are compensated dually by the government and the recipient. In this model regulations were adopted to prevent transplant tourism: foreigners were not allowed to receive a kidney from Iranian donors or donate a kidney to Iranian patients; however, they could be transplanted from donors of their own nationality, after full medical workup, with the authorization of the Ministry of Health. This was first considered as a humanitarian assistance to patients of the countries with no transplant program and limited and low quality dialysis. However, the policy of �foreign nationality transplant� gradually established a spot where residents of many countries, where living-unrelated donor transplant was illegal, could bring their donors and be transplanted mainly in private hospitals, with high incentives for the transplant teams. By June 2014, six hundred eight foreign nationality kidney transplants were authorized by Ministry of Health for citizens for 17 countries In this review, we examine the negative aspects of transplant for foreign citizens in Iran and the reasons that changed �travel for transplant� to �transplant tourism� in our country and finally led us to stop the program after more than 10 years. © Ba�kent University 2015 Printed in Turkey. All Rights Reserved

Dietary and fluid compliance: An educational intervention for patients having haemodialysis

Aim. This paper is a report of a study conducted to determine the effect of an educational intervention on dietary and fluid compliance in patients having haemodialysis. Background. Many of the clinical problems experienced by patients having haemodialysis are related to their failure to eat appropriate foods and restrict their fluid intake. Educational intervention in patients having haemodialysis to improve their compliance with dietary and fluid restrictions appears to be effective. Methods. Sixty-three patients having haemodialysis in three general hospitals in Tehran, Iran, were allocated into two groups at random for oral and/or video education. They were asked to give demographic and medical data. Bimonthly average values of serum potassium, sodium, calcium, phosphate, albumin, creatinine, uric acid, and blood urea nitrogen and interdialytic weight gain were measured before and after the teaching programmes. The data were collected in 2007. Findings. Compliance in terms of biochemical parameters and interdialytic weight gain was observed in 63·5 and 76·2 of patients in the oral and video teaching groups respectively. Statistically significant correlations were observed between demographic variables (age, educational level and occupation) and dietary and fluid compliances (P < 0·001). There was no difference between the effectiveness of two educational interventions. Conclusion. Nurses should emphasize sodium compliance in patients having haemodialysis and explain its adverse effects, such as excessive weight gain, hypertension, and peripheral oedema. © 2009 Blackwell Publishing Ltd