Predicting equilibrium states with Reynolds stress closures in channel flow and homogeneous shear flow

Turbulent channel flow and homogeneous shear flow have served as basic building block flows for the testing and calibration of Reynolds stress models. A direct theoretical connection is made between homogeneous shear flow in equilibrium and the log-layer of fully-developed turbulent channel flow. It is shown that if a second-order closure model is calibrated to yield good equilibrium values for homogeneous shear flow it will also yield good results for the log-layer of channel flow provided that the Rotta coefficient is not too far removed from one. Most of the commonly used second-order closure models introduce an ad hoc wall reflection term in order to mask deficient predictions for the log-layer of channel flow that arise either from an inaccurate calibration of homogeneous shear flow or from the use of a Rotta coefficient that is too large. Illustrative model calculations are presented to demonstrate this point which has important implications for turbulence modeling

Application of a new K-tau model to near wall turbulent flows

A recently developed K-tau model for near wall turbulent flows is applied to two severe test cases. The turbulent flows considered include the incompressible flat plate boundary layer with the adverse pressure gradients and incompressible flow past a backward facing step. Calculations are performed for this two-equation model using an anisotropic as well as isotropic eddy-viscosity. The model predictions are shown to compare quite favorably with experimental data

A critical evaluation of two-equation models for near wall turbulence

A variety of two-equation turbulence models,including several versions of the K-epsilon model as well as the K-omega model, are analyzed critically for near wall turbulent flows from a theoretical and computational standpoint. It is shown that the K-epsilon model has two major problems associated with it: the lack of natural boundary conditions for the dissipation rate and the appearance of higher-order correlations in the balance of terms for the dissipation rate at the wall. In so far as the former problem is concerned, either physically inconsistent boundary conditions have been used or the boundary conditions for the dissipation rate have been tied to higher-order derivatives of the turbulent kinetic energy which leads to numerical stiffness. The K-omega model can alleviate these problems since the asymptotic behavior of omega is known in more detail and since its near wall balance involves only exact viscous terms. However, the modeled form of the omega equation that is used in the literature is incomplete-an exact viscous term is missing which causes the model to behave in an asymptotically inconsistent manner. By including this viscous term and by introducing new wall damping functions with improved asymptotic behavior, a new K-tau model (where tau is identical with 1/omega is turbulent time scale) is developed. It is demonstrated that this new model is computationally robust and yields improved predictions for turbulent boundary layers

Swordfish growth pattern in the strait of Gibraltar; implications for mixing among Atlantic and Mediterranean stocks

A growth study of the swordfish in the Strait of Gibraltar was carried out, based on monthly size frequencies data collected from the Moroccan driftnet fishery during the period 2006-2011. The growth parameters were estimated by the modal progression analysis (MPA), using both the Bhattacharya and NORMSEP methods. The standard von Bertalanffy growth function (VBGF) for length was found to be: Lt =253.6 [1-exp (- 0.17(t + 1.30))]. The growth pattern of swordfish in the Strait of Gibraltar was found to be very similar to that obtained from past studies in various Mediterranean areas. Given the existing growth differences among Atlantic and Mediterranean swordfish, this suggests that the majority of fish caught in this area are most likely belonging to the Mediterranean stock. However, further studies are needed to identify the degree of mixing among stocks

Correlation of histological changes with IgG and thyroid hormone concentrations in nodular toxic goiter patient's.

Background : Thyroid disease includes many physiological disorders Toxic nodular goiter one of these disease involves an enlarged thyroid gland that reflex rounded growths called nodules. These nodules  is abnormal and produce too much thyroid hormone. Methods: This study was conducted to determinate the macroscopical and microscopical changes occurring in thyroid gland affected with toxic nodular goiter of both sexes, males and females. A total number of patients was 80 patients. 15 patients out of 80 were affected with nodular toxic goiter (2 male and 13 female). Results: Macroscopical examination showed the presence of mono and multinodular lesion with hypertrophy of some follicles and atrophy for other. Calcifications, haemorrhage, bundles of fibers were found with the matrix of thyroid tissues. Concerning microscopical examinations, it had been found that appearance of lymphoid nodules, cellular hypertrophy, hyperplasia and increase number of follicles cysts. Measurements of epithelium, colloid and follicles diameter were significantly (P<0.05) taller than healthy tissues. These changes might be attributed to continuous stimulating effects of thyroid which interne increase the activity of gland and tissues hypertrophied. Conclusion :Presence of various form of toxic goiter nodules correlated with many histological and  hormonal alterations in addition to enhancements of antibody concentration  . Key words: nodular goiter  ,  hyperplasia , fibrosis .TSH. Ig

Scope of Non-estrogenic Steroidal Congeners against Breast Cancer

Various novel non-estrogenic steroidal D-ring substituted analogs were synthesized and evaluated for their breast cancer activity against human breast cancer cell lines. The good cytotoxic results obtained against the breast cancer cell lines throws new insights into the field as the analogs are non 17β –Hydroxy estrogenic derivatives which are considered to be pivotal for the potent estrogenic activity. The synthesized steroidal analogs provide a very good platform for mechanistic studies of the interaction between non-esterogenic steroids and estrogen receptors

New results on the realizability of Reynolds stress turbulence closures

The realizability of Reynolds stress models in homogeneous turbulence is critically assessed from a theoretical standpoint. It is proven that a well known second-order closure formulated by Shih and Lumley using the strong realizability constraints of Schumann is, in fact, not a realizable model. The problem arises from the failure to properly satisfy the necessary positive second time derivative constraint when a principal Reynolds stress vanishes - a fatal flaw that becomes apparent when the non-analytic terms in their model are made single-valued as required on physical grounds. It is furthermore shown that the centrifugal acceleration generated by rotations of the principal axes of the Reynolds stress tensor can make the second derivative singular at the most extreme limits of realizable turbulence. This previously overlooked effect appears to make it impossible to identically satisfy the strong form of realizability in any version of the present generation of second-order closures. On the other hand, models properly formulated to satisfy the weak form of realizability - wherein states of one or two component turbulence are not accessible in finite time are found to be realizable. However, unlike the simpler and more commonly used second order closures, these models can be ill-behaved near the extreme limits of realizable turbulence due to the way that higher-degree nonlinearities are often unnecessarily introduced to satisfy realizability. Illustrative computations of homogeneous shear flows are presented to demonstrate these points which can have important implications for turbulence modeling

Side effect profile of hepatitis C treatment with peginterferon alpha-2b and ribavarin

Background: The major types of side effects include fatigue, influenza-like symptoms, gastrointestinal disturbances, neuropsychiatric symptoms and hematologic abnormalities. These side effects may be treatment limiting and require dose reduction or drug discontinuation objectives of the study was to assess the side effect profile of hepatitis C treatment (peginterferon alpha-2b and ribavarin) in Kashmiri patients attending the Department of Gastroenterology skims.Methods: In this study, all consecutive patients of hepatitis C infection on peginterfron and ribavarin treatment were enrolled after written consent. The patients underwent intervention treatment taking pegylated interferon α-2b (Viraferon, Schering Plough Corp., Kenilworth, NJ) and ribavirin in accordance with the standard protocol. Patients were monitored through weekly referrals while taking the medications. A detailed history was taken and complete physical examination done each time the patient presented to the hospital necessary blood sampling was taken.Results: During the study period of 2 years,105 Patients were enrolled 55 (52.4%) were males with a male:female ratio of 1.1:1.0. and mean age 37.6 years with a range of 13-75 years 7 patients (6.6) had a history of needle pricks, 4 patients (2.2%) of sharing same razors at barber’s shop. 4 (3.8%) patients of drug abuse; out of which 3 (2.8%) were intravenous drug abusers, Anemia occurred in 17 (16.2%) patients with requirement of dose modification w in 11 (10.4%) patients and dose stoppage in 1 (0.95%) patient in whom Hb dropped to less than 7, thrombocytopenia occurred in 27 (25.7%) patients with requirement of dose modification in 13 (12.3%) patients and dose stoppage in 1 (0.95%) patients due to platelet count decreasing to less than 30,000. Neutropenia as defined by ANC less than 1500 occurred in 22 (20.9%) patients.Conclusions: Dose modification was required in 48 (45.7%) patients, 30 (28.5%) patients required dose modifications due to labortory abnormalities and 18 (17.1%) due to other side effects. In 8 (7.6%) patients dose was discontinued due to adverse events (including psychosis in 1, severe flu like symptoms in 3, dermatitis in 1, depression in 3)

Double burden of malnutrition in children aged 24 to 59 months by socioeconomic status in five South Asian countries: evidence from demographic and health surveys

Objectives We aimed to investigate the socioeconomic inequalities in the burden of underweight and overweight among children in South Asia. We also examined other factors that were associated with these outcomes independently of household’s socioeconomic status. Design Nationally-representative surveys. Settings Demographic and Health Surveys from Bangladesh, India, Pakistan, Maldives and Nepal, which were conducted between 2009 and 2016. Participants Children aged 24 to 59 months with valid measurement for height and weight (n=146 996). Primary exposure and outcome measures Primary exposures were household’s wealth index and level of education. Underweight and overweight were defined according to the WHO and International Obesity Task Force definitions, respectively. Results Underweight prevalence was 37% in Bangladesh, 38% in India, 19% in Maldives, 29% in Nepal and 28% in Pakistan. Bangladesh, India and Nepal had similar overweight prevalence (between 2% and 4%) whereas Pakistan (7%) and Maldives (9%) had higher prevalence. Households with higher wealth index or education had lower odds of having underweight children. Adjusted ORs of underweight for richest versus poorest households were 0.4 (95% CI: 0.3 to 0.5), 0.5 (95% CI: 0.5 to 0.6), 0.5 (95% CI: 0.2 to 1.4), 0.5 (95% CI: 0.3 to 0.8) and 0.7 (95% CI: 0.5 to 1.1) for Bangladesh, India, Maldives, Nepal and Pakistan, respectively. Compared with poorest households, richest households were more likely to have overweight children in all countries except Pakistan, but such associations were not significant after adjustment for other factors. There were higher odds of having overweight children in households with higher education in Bangladesh (OR 2.1 (95% CI: 1.3 to 3.5)), India (OR 1.2 (95% CI: 1.2 to 1.3)) and Pakistan (OR 1.8 (95% CI: 1.1 to 2.9)) when compared with households with no education. Maternal nutritional status was consistently associated with children’s nutritional outcomes after adjustments for socioeconomic status. Conclusions Our study provides evidence for socioeconomic inequalities for childhood underweight and overweight in South Asian countries, although the directions of associations for underweight and overweight might be different