186 research outputs found

    A methodology for wellbore stability analysis of drilling into presalt formations: A case study from southern Iran

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    Drilling into presalt formations has been a long-standing issue due to the rapid changes in the diameter of the borehole during drilling operations either because of creep or wash-out dissolution. There have been many studies on characterization of salts, with many mathematical models being presented to estimate the pressure induced due to the squeezing salt sheets. However, the results of none of these models have been fully validated against real field data and some recommendations have been made based on numerical simulations. In this study, attempts were made to introduce a methodology based on damage mechanics for wellbore stability analysis of a wells drilled in the southern part of Iran. The results obtained indicated that the presence of a thick salt layer in the well has resulted in significant wellbore closure in the intervals above the reservoir section. It was also found that the salt exhibits viscoelastic behaviour during drilling due to the homogeneous temperature which has not reached the threshold limit of viscoplastic boundary. A complicated change in the stress regime was also observed which could be linked to the existence of the thick salt layer or presences of a fault crossing the well. Therefore, it is recommended to further validate this model in other wells using the methodology presented

    Relationship between dietary virgin olive oil on brain cholesterol, cholesteryl ester and triglyceride levels and blood brain barrier (BBB) permeability in a rat stroke model

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    Introduction: Recent studies suggest that dietary virgin olive oil (VOO) reduces hypoxia-re oxygenation injury in rat brain. We have attempted to determine the effect of dietary virgin olive oil on brain lipidomics and its relationship with brain edema in a rat stroke model. Methods: Five groups, each consisting of 6 male Wistar rats, were studied. The first and second groups (control and sham) received distilled water, while three treatment groups received oral VOO for 30 days (0.25, 0.5 and 0.75 ml/kg/day, respectively). Two hours after the last dose, each main group was subdivided into middle cerebral artery occlusion (MCAO)-operated and intact subgroups for assessment of neuropathology (blood brain barrier permeability) and brain lipid analysis. Results: VOO increased the brain cholesteryl ester and cholesterol levels in doses of 0.5 and 0.75 ml/kg/day. VOO in all three doses increased the brain triglyceride levels (p<0.05). Oral administration of VOO reduces infarct volume, brain edema, blood brain barrier permeability, after transient MCAO in rats. Conclusion: Although further studies are needed to clarify the mechanisms of ischemic tolerance, VOO is partly associated with increased levels of brain cholesteryl ester, cholesterol and triglyceride in rats

    Body image and meta-worry as mediators of body dysmorphic disorder

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    Objectives: Meta-worry and attitudes towards the body have been largely overlooked as potential risk factors for body dysmorphic disorder (BDD) despite theorizing that a negative body image may play a critical role in the development of this disorder. Participants: The purpose of this study was to evaluate the fit of a theoretical model specifying body image and meta-worry as mediators between cognitive, metacognitive beliefs and body dysmorphic disorder(BDD) in a nonclinical sample of 635 participants (304 male and 331 female). Results: The data supported the model, and meta-worry and body image significantly mediated the relationship between cognitive, metacognitive beliefs and BDD. These findings provide essential preliminary evidence that body image may represent a necessary but not sufficient risk factor for BDD and that treatment for BDD should consider targeting body-related pathology in addition to meta-worry. Conclusion: The model may prompt future research into body dysmorphic disorder

    Identification of AFLP markers linked with cocoon weight genes in silkworm (Bombyx mori L.)

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    DNA markers used in assisting selection method is a safe method in breeding process, due to deletion of environmental conditions, and it is an important tool in preparing linkage map and QTLs mapping. In mulberry silkworm that is, foundation of world sericulture, its major production-economic characteristics are polygenic. In this study, we want to determine QTL(s) affecting cocoon weight trait by AFLP markers. For this reason, we used 20 selected primer combinations from among 81 primers combinations of PstI/TaqI at the level of three F2 populations including 33, 36 and 34 offsprings sample, respectively. These populations were obtained by crossing two lines of Lemon Khorasan (as maternal) and 107 (as paternal). The parental lines, F1 and F2 individuals&#8217; DNA were extracted with phenolchloroform method. Then they were digested by two restriction enzymes (TaqI and PstI) and amplified by using of appropriate adaptors. These amplified samples are transfered on annealed 6% polyacrylamide gels. After genotyping of individuals, the linkage maps of populations were drawn by Map manager/QTX and QTL Cartographer ver.2.5 softwares. Number of total and polymorphic bands that formed to 20 primer combinations in each populations were 930, 944, 810 and 142, 171, 178 bands, respectively. Therefore polymorphic frequencies were 15.27, 18.11 and 21.97%. The obtained linkage maps were included in 16, 18 and 24 linkage groups. The total length of this linkage maps and average distance between two markers were 2186.40, 2582.50 and 2392.60 cM, and 18.37, 16.45 and 14.95 cM, respectively. The detection of QTLs numbers of cocoon weight character in each F2 populations also showed 1, 6 and 1 loci in LRS&gt;17 (LOD &gt; 3.7) by compound interval mapping methods, respectively

    Property and Shape Modulation of Carbon Fibers Using Lasers

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    An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes

    Efficient upconversion of sub-THz radiation in a high-Q whispering gallery resonator

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    We demonstrate efficient upconversion of sub-THz radiation into the optical domain in a high-Q whispering gallery mode resonator with quadratic optical nonlinearity. The 5x10^{-3} power conversion efficiency of continuous wave 100GHz signal is achieved with only 16 mW of optical pump.Comment: This revision is limited to discussion of only optical WGMs coupled with the external Rf field. Discussion of RF WGMs is now posted separatel

    Primary recovery factor as a function of production rate: implications for conventional reservoirs with different drive mechanisms

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    This study evaluates the dependency of production rate on the recovery of hydrocarbon from conventional reservoirs using MBAL simulator. The results indicated that the recoveries are sensitive to the production rate in almost all hydrocarbon reservoirs. It was also found that the recovery of volumetric gas drive reservoirs is not impacted by the production rate. In fact, any increase in the production rate improves gas recovery in weak and strong water drive reservoirs. Moreover, increasing the production rate in oil reservoirs decreases the recovery with a significant effect observed in the weak water drive reservoirs. The results of this study demonstrate the need for implementing an effective reservoir management in order to obtain a maximum recovery

    MEASURING SPATIAL ACCESSIBILITY TO HEALTHCARE FACILITIES IN ISFAHAN METROPOLITAN AREA IN IRAN

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    Appropriate spatial accessibility to healthcare facilities is an important component of the efficient delivery of healthcare. This study aims to measure spatial accessibility to healthcare facilities in Isfahan Metropolitan Area, a rapidly growing megacity in Iran. We used two methods of population-weighted fuzzy analytic hierarchy process and the two-step floating catchment area (2SFCA) to measure spatial accessibility to urban healthcare facilities, including hospitals, pharmacies, clinics, and laboratories. The results of these two methods were compared. Not surprisingly, the center of Isfahan has the highest accessibility scores for healthcare facilities, and the peripheral areas of the city have the lowest levels. Despite the existence of higher numbers of healthcare facilities in northern parts of Isfahan, accessibility to healthcare facilities is low because of the large population. Both methods show that healthcare services are not evenly distributed in Isfahan. Some areas with a high population have low accessibility to health facilities. Ideally, these areas would be prioritized for future health infrastructure investment. The methods used here can help urban healthcare policymakers identify spatial inequalities in access to care and thus target the areas in need

    Comparison of anthro-metabolic indicators for predicting the risk of metabolic syndrome in the elderly population: Bushehr Elderly Health (BEH) program

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    Background Metabolic syndrome (MetS) is a cluster metabolic disorder that includes central obesity, insulin resistance, hypertension, and dyslipidemia, and is highly associated with an increased risk of developing non-communicable diseases (NCDs). This study aimed to compare the reliability of anthro-metabolic indices [visceral adiposity index (VAI), body roundness index (BRI), and a body shape index (BSI), body adiposity index (BAI), lipid accumulation product (LAP), waist to hip ratio, and waist to height ratio] in predicting MetS in Iranian older people. Methods This cross-sectional study was conducted based on the data of 2426 adults aged ≥60 years that participated in the second stage of the Bushehr Elderly Health (BEH) program, a population-based prospective cohort study being conducted in Bushehr, Iran. MetS was defined based on the revised National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) criteria. The receiver operating characteristic (ROC) curve analysis was used to assess predictive performance of anthro-metabolic indices and determine optimal cutoff values. Logistic regression analysis was applied to determine the associations between MetS and indices. Results 2426 subjects (48.1% men) with mean ± SD age of 69.34 ± 6.40 years were included in the study. According to ATP III criteria, 34.8% of men and 65.2% of women had MetS (P < 0.001). Of the seven examined indices, the AUCs of VAI and LAP in both genders were higher than AUCs of other anthro-metabolic indices. Also, in general population, VAI and LAP had the greatest predictive power for MetS with AUC 0.87(0.86–0.89) and 0.87(0.85–0.88), respectively. The lowest AUC in total population belonged to BSI with the area under the curve of 0.60(0.58–0.62). After adjusting for potential confounders (e.g. age, sex, education, physical activity, current smoking) in the logistic regression model, the highest OR in the total population was observed for VAI and LAP, which was 16.63 (13.31–20.79) and 12.56 (10.23–15.43) respectively. The lowest OR for MetS was 1.93(1.61–2.30) for BSI. Conclusion This study indicated that both VAI and LAP are the most valuable indices among the anthro-metabolic indices to identify MetS among the elderly in both genders. So, they could be used as proper assessment tools for MetS in clinical practice. However, the cost-benefit of these indices compared to the ATP III criteria need further studies
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