558 research outputs found

    Thermal stratification and circulation of water bodies subjected to thermal discharge

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    A three-dimensional analytical model for large water bodies is presented. Time histories and spatial distribution of pressure, velocity and temperature in water bodies, subjected to thermal discharge, are determined employing a digital computer. The dynamic response is obtained for a rectangular water body by applying a finite difference method to the mass, momentum and energy balance equations. These partial differential equations are algebraically manipulated to obtain; 1) three parabolic differential equations integrated temporally to find the horizontal velocity components and temperature; 2) one algebraic integral equation to get the vertical velocity component; 3) one elliptic differential equation integrated spatially to find the pressure; and 4) one differential equation to get the water level. Numerical stability criteria are developed which facilitate the selection of space and time increments for stable numerical integration. The distinctive feature of this analysis, as compared to previous studies, is the calculation of pressure and water level from equations of motion without simplifying assumptions such as hydrostatic pressure approximation and rigid-lid concept. The mathematical formulation is verified by applying this analysis to cases where the final steady state flow patterns have been determined analytically or experimentally by others. In particular, the final steady state solution obtained from this dynamic analysis is verified with existing flow measurements of laminar flow development in a square duct. Furthermore, the natural circulation flows developed by this analysis are verified with known flow patterns in partially heated ponds. The problem of thermal discharge entering a river with known initial velocity and temperature distribution is then analyzed. The time histories of the velocity and temperature distribution as well as the velocity and temperature profiles are obtained. These results provide the values of temperature rise and the rate of temperature rise needed for the assessment of the extent of thermal pollution in water bodies

    Psychometric properties of the king spiritual intelligence questionnaire (KSIQ) in physical veterans of Iran-Iraq warfare

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    Aims: The study's purpose was to determine reliability and validity of the King spiritual intelligence questionnaires in veterans of Iran-Iraq Warfare. Methods: In this cross sectional study, 300 veterans of the Iran-Iraq war completed the King spiritual intelligence questionnaires. Principal components analysis (PCA) with varimax rotation was used to assess domain structure of the King spiritual intelligence questionnaires. Internal and external consistency reliability was assessed with Cronbach's alpha and intra-class correlation coefficient (ICC). Results: Internal consistency of King spiritual intelligence questions estimated with Cronbach's alpha, 0.872 and intra-class correlation coefficient (ICC).872 (CI 95%: 0.84 -0.89). The construct validity of the questionnaire was calculated using exploratory factor analysis that showed 3 factors with Eigen values of greater than one, which explained in total 44.7% of the variance. (1, 8 items, α= 0.87; 2, 5. items; α = 0.89; 3, 2 items, α= 0.51). Conclusion: The Persian version of King spiritual intelligence questionnaire demonstrated suitable validity and reliability among the Veterans of Iran-Iraq Warfare. With the consideration of the proper psychometric characteristics, this questionnaire can be used to further research spiritual intelligence in this population

    Comparing Three Data Mining Methods to Predict Kidney Transplant Survival

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    Introduction: One of the most important complications of post-transplant is rejection. Analyzing survival is one of the areas of medical prognosis and data mining, as an effective approach, has the capacity of analyzing and estimating outcomes in advance through discovering appropriate models among data. The present study aims at comparing the effectiveness of C5.0 algorithms, neural network and C & RTree to predict kidney transplant survival before transplant. Method: To detect factors effective in predicting transplant survival, information needs analysis was performed via a researcher-made questionnaire. A checklist was prepared and data of 513 kidney disease patient files were extracted from Sina Urology Research Center. Following CRISP methodology for data mining, IBM SPSS Modeler 14.2, C5.0, C&RTree algorithms and neural network were used. Results: Body Mass Index (BMI), cause of renal dysfunction and duration of dialysis were evaluated in all three models as the most effective factors in transplant survival. C5.0 algorithm with the highest validity (96.77) was the first in estimating kidney transplant survival in patients followed by C&RTree (83.7) and neural network (79.5) models. Conclusion: Among the three models, C5.0 algorithm was the top model with high validity that confirms its strength in predicting survival. The most effective kidney transplant survival factors were detected in this study; therefore, duration of transplant survival (year) can be determined considering the regulations set for a new sample with specific characteristics. © 2016 Leila Shahmoradi, Mostafa Langarizadeh, Gholamreza Pourmand, Ziba Aghsaei fard, and Alireza Borhani

    Texture analysis on preoperative contrast-enhanced magnetic resonance imaging identifies microvascular invasion in hepatocellular carcinoma

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    Background: Radiomic texture analysis quantifies tumor heterogeneity. The aim of this study is to determine if radiomics can predict biologic aggressiveness in HCC and identify tumors with MVI.Methods: Single-center, retrospective review of HCC patients undergoing resection/ablation with curative intent from 2009 to 2017. DICOM images from preoperative MRIs were analyzed with texture analysis software. Texture analysis parameters extracted on T1, T2, hepatic arterial phase (HAP) and portal venous phase (PVP) images. Multivariate logistic regression analysis evaluated factors associated with MVI.Results: MVI was present in 52.2% (n = 133) of HCCs. On multivariate analysis only T1 mean (OR = 0.97, 95%CI 0.95-0.99, p = 0.043) and PVP entropy (OR = 4.7, 95%CI 1.37-16.3, p = 0.014) were associated with tumor MVI. Area under ROC curve was 0.83 for this final model. Empirical optimal cutpoint for PVP tumor entropy and T1 tumor mean were 5.73 and 23.41, respectively. At these cutpoint values, sensitivity was 0.68 and 0.5, respectively and specificity was 0.64 and 0.86. When both criteria were met, the probability of MVI in the tumor was 87%.Conclusion: Tumor entropy and mean are both associated with MVI. Texture analysis on preoperative imaging correlates with microscopic features of HCC and can be used to predict patients with high-risk tumors

    Anomalous left brachiocephalic vein: important vascular anomaly concomitant with congenital anomalies and heart diseases

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    Background: Anomalous left brachiocephalic vein (ALBCV) is a rare and less known systemic venous anomaly. Infrequently, this vein takes an abnormal course and passes to the right behind or beneath the aortic arch to create the superior vena cava (SVC). Its incidence was reported much higher in patients with congenital heart disease especially in conotruncal and aortic arch anomalies. It could be misdiagnosed with normal or abnormal mediastinal structures. It also could make complication during surgeries or invasive strategies. Previously, this anatomical finding has been reported in case reports and there are just few studies evaluating these patients as a group to find other abnormalities Materials and methods: We conducted a retrospective, multicentre study between 2008 and 2014 at three institutions. We reviewed thoracic computed tomography angiography of 1372 patients referred to these centres. The diagnosis of ALBCV was confirmed by an expert radiologist and the imagings were reassessed to identify new cases and concomitant anomalies. We analysed the imagings’ details and measured the prevalence of each anomaly. Results: Among the 22 cases of ALBCV, 12 (54.5%) and 10 (45.4%) patients were males and females, respectively, with median age of 12.5 years. Tetralogy of Fallot (TOF) was considered as a most concomitant anomaly with ALBCV (54.5%). Two patients had associated atrial septal defect (ASD) and defined as pentalogy of Fallot. Right-sided aortic arc (RSAA) was detected in 12 (54.5%) patients; mirror image was found in 5 of them. Pure ventricular septal defect or pulmonary stenosis without TOF was recognised in 4 patients. Three cases had isolated overriding aorta (13.6%). In 3 patients, we could find patent ductus arteriosus (13.6%). In 2 (9%) patients, abdominal haemangioma was incidentally diagnosed. Aberrant left retrotracheal subclavian artery was detected in 1 (4.5%) patient. One patient only had isolated ALBCV (4.5%). Conclusions: In our study, ALBCV was frequently seen in association with other congenital anomalies. mostly TOF and RSAA. In patients with pulmonary hypoplasia or aplasia, some parts of lung’s blood supply were provided by abnormal aorto-pulmonary connections. For a radiologist, it is important to differentiate this anomaly in cross-sectional imaging from persistent left SVC, partial anomalous pulmonary veins return and an enlarged lymph node. Detection of ALBCV could draw the attention to the more serious heart disease and in isolated forms prevented further evaluations.

    Metastatic extrapleural malignant solitary fibrous tumor presenting with hypoglycemia (Doege–Potter syndrome)

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    AbstractWe report a rare case of metastatic malignant solitary fibrous tumor (SFT) that presented with hypoglycemia because of insulin growth factor-2 production. Initial workup included computed tomography imaging that revealed a large, partially necrotic liver mass, a hypervascular pancreatic head lesion, and 2 renal lesions. Following hepatic resection, pancreatic head resection and nephrectomy, all these lesions demonstrated pathological findings that were consistent with SFT. The patient also had a history of an intracranial mass that had been previously resected and treated with gamma knife therapy at an outside institution, which was found to also be SFT. Six months after initial pancreatic head resection, the patient developed a new lesion involving the pancreatic tail that was found to represent recurrent metastatic SFT. This case emphasizes the highly aggressive nature of extrapleural SFT, while rare, and the role of imaging in follow-up for disease recurrence

    Suppression of experimental abdominal aortic aneurysms in the rat by treatment with angiotensin-converting enzyme inhibitors

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    AbstractPurpose: Pathologic remodeling of the extracellular matrix is a critical mechanism in the development and progression of abdominal aortic aneurysms (AAAs). Although angiotensin-converting enzyme (ACE) inhibitors are known to alter vascular wall remodeling in other conditions, their effects on AAAs are unknown. In this study we assessed the effect of ACE inhibitors in a rodent model of aneurysm development. Methods: Male Wistar rats underwent transient aortic perfusion with porcine pancreatic elastase, followed by treatment with one of three ACE inhibitors (captopril [CP], lisinopril [LP], or enalapril [EP]), an angiotensin (AT)1 receptor antagonist (losartan [LOS]), or water alone (9 rats in each group). Blood pressure and aortic diameter (AD) were measured before elastase perfusion and on day 14, with an AAA defined as an increase in AD (ΔAD) of more than 100%. The structural features of the aortic wall were examined by means of light microscopy. Results: Aneurysmal dilatation consistently developed within 14 days of elastase perfusion in untreated rats, coinciding with the development of a transmural inflammatory response and destruction of the elastic media (mean ΔAD, 223% ± 28%). All three ACE inhibitors prevented AAA development (mean ΔAD: CP, 67% ± 4%; LP, 18% ± 12%; and EP, 14% ± 3%; each P <.05 vs controls). ACE inhibitors also attenuated the degradation of medial elastin without diminishing the inflammatory response. Surprisingly, the aneurysm-suppressing effects of ACE inhibitors were dissociated from their effects on systemic hemodynamics, and LOS had no significant effect on aneurysm development compared with untreated controls (mean ΔAD, 186% ± 19%). Conclusion: Treatment with ACE inhibitors suppresses the development of elastase-induced AAAs in the rat. Although this is associated with the preservation of medial elastin, the mechanisms underlying these effects appear to be distinct from hemodynamic alterations alone or events mediated solely by AT1 receptors. Further studies are needed to elucidate how ACE inhibitors influence aortic wall matrix remodeling during aneurysmal degeneration. (J Vasc Surg 2001;33:1057-64.

    Suppression of experimental abdominal aortic aneurysms in the rat by treatment with angiotensin-converting enzyme inhibitors

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    AbstractPurpose: Pathologic remodeling of the extracellular matrix is a critical mechanism in the development and progression of abdominal aortic aneurysms (AAAs). Although angiotensin-converting enzyme (ACE) inhibitors are known to alter vascular wall remodeling in other conditions, their effects on AAAs are unknown. In this study we assessed the effect of ACE inhibitors in a rodent model of aneurysm development. Methods: Male Wistar rats underwent transient aortic perfusion with porcine pancreatic elastase, followed by treatment with one of three ACE inhibitors (captopril [CP], lisinopril [LP], or enalapril [EP]), an angiotensin (AT)1 receptor antagonist (losartan [LOS]), or water alone (9 rats in each group). Blood pressure and aortic diameter (AD) were measured before elastase perfusion and on day 14, with an AAA defined as an increase in AD (ΔAD) of more than 100%. The structural features of the aortic wall were examined by means of light microscopy. Results: Aneurysmal dilatation consistently developed within 14 days of elastase perfusion in untreated rats, coinciding with the development of a transmural inflammatory response and destruction of the elastic media (mean ΔAD, 223% ± 28%). All three ACE inhibitors prevented AAA development (mean ΔAD: CP, 67% ± 4%; LP, 18% ± 12%; and EP, 14% ± 3%; each P <.05 vs controls). ACE inhibitors also attenuated the degradation of medial elastin without diminishing the inflammatory response. Surprisingly, the aneurysm-suppressing effects of ACE inhibitors were dissociated from their effects on systemic hemodynamics, and LOS had no significant effect on aneurysm development compared with untreated controls (mean ΔAD, 186% ± 19%). Conclusion: Treatment with ACE inhibitors suppresses the development of elastase-induced AAAs in the rat. Although this is associated with the preservation of medial elastin, the mechanisms underlying these effects appear to be distinct from hemodynamic alterations alone or events mediated solely by AT1 receptors. Further studies are needed to elucidate how ACE inhibitors influence aortic wall matrix remodeling during aneurysmal degeneration. (J Vasc Surg 2001;33:1057-64.

    A practice-inspired mindset for researching the psychophysiological and medical health effects of recreational dance (dance pport)

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    “Dance” has been associated with many psychophysiological and medical health effects. However, varying definitions of what constitute “dance” have led to a rather heterogenous body of evidence about such potential effects, leaving the picture piecemeal at best. It remains unclear what exact parameters may be driving positive effects. We believe that this heterogeneity of evidence is partly due to a lack of a clear definition of dance for such empirical purposes. A differentiation is needed between (a) the effects on the individual when the activity of “dancing” is enjoyed as a dancer within different dance domains (e.g., professional/”high-art” type of dance, erotic dance, religious dance, club dancing, Dance Movement Therapy (DMT), and what is commonly known as hobby, recreational or social dance), and (b) the effects on the individual within these different domains, as a dancer of the different dance styles (solo dance, partnering dance, group dance; and all the different styles within these). Another separate category of dance engagement is, not as a dancer, but as a spectator of all of the above. “Watching dance” as part of an audience has its own set of psychophysiological and neurocognitive effects on the individual, and depends on the context where dance is witnessed. With the help of dance professionals, we first outline some different dance domains and dance styles, and outline aspects that differentiate them, and that may, therefore, cause differential empirical findings when compared regardless (e.g., amount of interpersonal contact, physical exertion, context, cognitive demand, type of movements, complexity of technique and ratio of choreography/improvisation). Then, we outline commonalities between all dance styles. We identify six basic components that are part of any dance practice, as part of a continuum, and review and discuss available research for each of them concerning the possible health and wellbeing effects of each of these components, and how they may relate to the psychophysiological and health effects that are reported for “dancing”: (1) rhythm and music, (2) sociality, (3) technique and fitness, (4) connection and connectedness (self-intimation), (5) flow and mindfulness, (6) aesthetic emotions and imagination. Future research efforts might take into account the important differences between types of dance activities, as well as the six components, for a more targeted assessment of how “dancing” affects the human body
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