A vortex method for viscous unsteady flows

A simple method is presented for the creation of vorticity from a solid boundary in the form of discrete vortex blobs. These vortices have uniform-vorticity cores and are released from a number of points distributed around the body surface at a small distance away from the surface. Their strengths are obtained by satisfying the no-slip condition at the midpoints of the corresponding vortex sheets. The dynamics of these vortices is then considered by including the effect of viscous diffusion by random13; walk approach. The method is applied to the starting flow past a circular cylinder. A detailed parametric study shows that viscosity has the most significant effect on13; the computed results and, in order to obtain meaningful results, it must be reduced suitably to compensate for the artificial viscosity arising from numerical integration13; of equations of motion of the discrete vortices. Results are obtained for three typical Reynolds numbers of 9500, 3000 and 550, and are found to be in very good agreement13; with experimental measurements for the centerline velocity distribution. In particular, the case of Re=550 illustrates the usefulness of the present model even at low Reynolds numbers. The vortex patterns, velocity vectors and particle path lines also conform to the experimental flow visualization pictures. Though the method is developed for a simple configuration like a circular cylinder, it can be easily extended to any general13; body shape

Study of risk factors causing coronary heart disease among army personnel of the rank non-commissioned officers and below in the age group of 20-50 years and its association with prehypertension

Background: Coronary heart disease (CHD) is an acute public health problem both in developed and in developing countries, like India. Assessing the prevalence of CHD in the community is equivalent to assessing the tip of the iceberg. Hypertension is a major risk factor for CHD and hypertension disease prevalence tip of the iceberg in the community is much more obscure. Objective: The objective of the study was to carry out a cross-sectional study among serving Army personnel, comprising healthy non-commissioned officers and other rank personnel to successfully assess the risk factors for CHD and their association with prehypertension. Materials and Methods: Screening of risk factors for CHD among 200 randomly selected participants was carried out. Blood pressure, height, weight, serum total cholesterol, serum triglycerides, serum high-density lipoprotein (HDL), random blood sugar levels, and smoking status were the major risk factors screened. Results: Nearly 63% of Army personnel were found to be having blood pressure commensurate to the range of prehypertension. About 15% were detected to be overweight, 22% had hypercholesterolemia, 5.4% had impaired glucose tolerance (IGT), and 19.2% were current smokers. Higher age, body mass index, high serum triglycerides, low serum HDL, and IGT were found to be independently associated with increased prevalence of prehypertension in multiple logistic regression analysis. Conclusion: Our findings recommend the constant monitoring of CHD risk factors and the formulation of effective preventive strategies for adequate control of alarming incidence

Why should we invest in health? Evidence from the lens of second-order benefits of health

Life expectancy and access to health care have both increased globally in recent decades, and these innovations have significantly improved well-being. As a result, health reforms are increasingly becoming a top concern in all countries in order to address/increase accessibility, affordability, and availability of quality services, as well as improve spending efficiencies. There are many evidenced benefits which are secondary to the health benefits of those programmes. However, second-order benefits of health schemes have received little attention and are rarely discussed in mainstream policy and practice. The paper intends to contribute to broader initiatives to recognise health schemes as vital in achieving equitable and inclusive development that benefits the entire community. The logical framework technique was used to analyse the health schemes' second-order benefits. The primary and secondary objectives, methods, outcomes, and impacts were compared. Apart from the health programmes’ own objectives, the analysis revealed extensive benefits such as employment opportunities, local partnerships with communities, decreased inequalities and population-level impacts on socio-economic development, women empowerment, increase in literacy and school completion rates, and decrease in out-of-pocket expenditure. The economic impact of investing in health systems by creating high-quality jobs and purchasing goods and services from local businesses is highlighted by the second-order health advantages, which are in relation to the primary benefits. Not only do healthcare systems play an important role in the economies of the nation, but also in the social lives of these communities

Nonlinear Hydrodynamics from Flow of Retarded Green's Function

We study the radial flow of retarded Green's function of energy-momentum tensor and $R$-current of dual gauge theory in presence of generic higher derivative terms in bulk Lagrangian. These are first order non-linear Riccati equations. We solve these flow equations analytically and obtain second order transport coefficients of boundary plasma. This way of computing transport coefficients has an advantage over usual Kubo approach. The non-linear equation turns out to be a linear first order equation when we study the Green's function perturbatively in momentum. We consider several examples including $Weyl^4$ term and generic four derivative terms in bulk. We also study the flow equations for $R$-charged black holes and obtain exact expressions for second order transport coefficients for dual plasma in presence of arbitrary chemical potentials. Finally we obtain higher derivative corrections to second order transport coefficients of boundary theory dual to five dimensional gauge supergravity.Comment: Version 2, reference added, typos correcte

Traditional use of medicinal plants by the Jaintia tribes in North Cachar Hills district of Assam, northeast India

The study of ethnobotany relating to any tribe is in itself a very intricate or convoluted process. This paper documents the traditional knowledge of medicinal plants that are in use by the indigenous Jaintia tribes residing in few isolated pockets of northeast India. The present study was done through structured questionnaires in consultations with the tribal practitioners and has resulted in the documentation of 39 medicinal plant species belonging to 27 families and 35 genera. For curing diverse form of ailments, the use of aboveground plant parts was higher (76.59%) than the underground plant parts (23.41%). Of the aboveground plant parts, leaf was used in the majority of cases (23 species), followed by fruit (4). Different underground plant forms such as root, tuber, rhizome, bulb and pseudo-bulb were also found to be in use by the Jaintia tribe as a medicine. Altogether, 30 types of ailments have been reported to be cured by using these 39 medicinal plant species. The study thus underlines the potentials of the ethnobotanical research and the need for the documentation of traditional ecological knowledge pertaining to the medicinal plant utilization for the greater benefit of mankind

Effects of interactions between the constituents of chitosan-edible films on their physical properties

The main objective of this work was to evaluate the effect of chitosan and plasticizer concentrations and oil presence on the physical and mechanical properties of edible films. The effect of the film constituents and their in-between interactions were studied through the evaluation of permeability, opacity and mechanical properties. The effects of the studied variables (concentrations of chitosan, plasticizer and oil) were analysed according to a 2 3 factorial design. Pareto charts were used to identify the most significant factors in the studied properties (water vapour, oxygen and carbon dioxide permeability; opacity; tensile strength; elongation at break and Young's modulus). When addressing the influence of the interactions between the films' constituents on the properties above, results show that chitosan and plasticizer concentrations are the most significant factors affecting most of the studied properties, while oil incorporation has shown to be of a great importance in the particular case of transport properties (gas permeability), essentially due to its hydrophobicity. Water vapour permeability values (ranging from 1. 62 × 10 -11 to 4. 24 × 10 -11 g m -1 s -1 Pa -1) were half of those reported for cellophane films. Also the mechanical properties (tensile strength values from 0. 43 to 13. 72 MPa and elongation-at-break values from 58. 62% to 166. 70%) were in the range of those reported for LDPE and HDPE. Based on these results, we recommend the use of 1. 5% (w/w) chitosan concentration to produce films, where the oil and plasticizer proportions will have to be adjusted in a case-by-case basis according to the use intended for the material. This work provides a useful guide to the formulation of chitosan-based film-forming solutions for food packaging applications.The author MA Cerqueira is a recipient of a fellowship from Fundacao para a Ciencia e Tecnologia (FCT, SFRH/BD/23897/2005) and BWS Souza is a recipient of a fellowship from the Coordenacao Aperfeicoamento de Pessoal de Nivel Superior, Brazil (Capes, Brazil)

Hydrodynamics from charged black branes

We extend the recent work on fluid-gravity correspondence to charged black-branes by determining the metric duals to arbitrary charged fluid configuration up to second order in the boundary derivative expansion. We also derive the energy-momentum tensor and the charge current for these configurations up to second order in the boundary derivative expansion. We find a new term in the charge current when there is a bulk Chern-Simons interaction thus resolving an earlier discrepancy between thermodynamics of charged rotating black holes and boundary hydrodynamics. We have also confirmed that all our expressions are covariant under boundary Weyl-transformations as expected.Comment: 0+ 31 Pages; v2: 0+33 pages, typos corrected and new sections (in appendix) added; v3:published versio

Evolution of spiral and scroll waves of excitation in a mathematical model of ischaemic border zone

Abnormal electrical activity from the boundaries of ischemic cardiac tissue is recognized as one of the major causes in generation of ischemia-reperfusion arrhythmias. Here we present theoretical analysis of the waves of electrical activity that can rise on the boundary of cardiac cell network upon its recovery from ischaemia-like conditions. The main factors included in our analysis are macroscopic gradients of the cell-to-cell coupling and cell excitability and microscopic heterogeneity of individual cells. The interplay between these factors allows one to explain how spirals form, drift together with the moving boundary, get transiently pinned to local inhomogeneities, and finally penetrate into the bulk of the well-coupled tissue where they reach macroscopic scale. The asymptotic theory of the drift of spiral and scroll waves based on response functions provides explanation of the drifts involved in this mechanism, with the exception of effects due to the discreteness of cardiac tissue. In particular, this asymptotic theory allows an extrapolation of 2D events into 3D, which has shown that cells within the border zone can give rise to 3D analogues of spirals, the scroll waves. When and if such scroll waves escape into a better coupled tissue, they are likely to collapse due to the positive filament tension. However, our simulations have shown that such collapse of newly generated scrolls is not inevitable and that under certain conditions filament tension becomes negative, leading to scroll filaments to expand and multiply leading to a fibrillation-like state within small areas of cardiac tissue.Comment: 26 pages, 13 figures, appendix and 2 movies, as accepted to PLoS ONE 2011/08/0

A novel pathway producing dimethylsulphide in bacteria is widespread in soil environments

The volatile compound dimethylsulphide (DMS) is important in climate regulation, the sulphur cycle and signalling to higher organisms. Microbial catabolism of the marine osmolyte dimethylsulphoniopropionate (DMSP) is thought to be the major biological process generating DMS. Here we report the discovery and characterisation of the first gene for DMSP-independent DMS production in any bacterium. This gene, mddA, encodes a methyltransferase that methylates methanethiol (MeSH) and generates DMS. MddA functions in many taxonomically diverse bacteria including sediment-dwelling pseudomonads, nitrogen-fixing bradyrhizobia and cyanobacteria, and mycobacteria, including the pathogen Mycobacterium tuberculosis. The mddA gene is present in metagenomes from varied environments, being particularly abundant in soil environments, where it is predicted to occur in up to 76% of bacteria. This novel pathway may significantly contribute to global DMS emissions, especially in terrestrial environments, and could represent a shift from the notion that DMSP is the only significant precursor of DMS

Reduced level of arousal and increased mortality in adult acute medical admissions: a systematic review and meta-analysis

Abstract Background Reduced level of arousal is commonly observed in medical admissions and may predict in-hospital mortality. Delirium and reduced level of arousal are closely related. We systematically reviewed and conducted a meta-analysis of studies in adult acute medical patients of the relationship between reduced level of arousal on admission and in-hospital mortality. Methods We conducted a systematic review (PROSPERO: CRD42016022048), searching MEDLINE and EMBASE. We included studies of adult patients admitted with acute medical illness with level of arousal assessed on admission and mortality rates reported. We performed meta-analysis using a random effects model. Results From 23,941 studies we included 21 with 14 included in the meta-analysis. Mean age range was 33.4 - 83.8 years. Studies considered unselected general medical admissions (8 studies, n=13,039) or specific medical conditions (13 studies, n=38,882). Methods of evaluating level of arousal varied. The prevalence of reduced level of arousal was 3.1%-76.9% (median 13.5%). Mortality rates were 1.7%-58% (median 15.9%). Reduced level of arousal was associated with higher in-hospital mortality (pooled OR 5.71; 95% CI 4.21-7.74; low quality evidence: high risk of bias, clinical heterogeneity and possible publication bias). Conclusions Reduced level of arousal on hospital admission may be a strong predictor of in-hospital mortality. Most evidence was of low quality. Reduced level of arousal is highly specific to delirium, better formal detection of hypoactive delirium and implementation of care pathways may improve outcomes. Future studies to assess the impact of interventions on in-hospital mortality should use validated assessments of both level of arousal and delirium