Non-dispersive and weakly dispersive single-layer flow over an axisymmetric obstacle: the equivalent aerofoil formulation

Non-dispersive and weakly dispersive single-layer flows over axisymmetric obstacles, of non-dimensional height M measured relative to the layer depth, are investigated. The case of transcritical flow, for which the Froude number F of the oncoming flow is close to unity, and that of supercritical flow, for which F > 1, are considered. For transcritical flow, a similarity theory is developed for small obstacle height and, for non-dispersive flow, the problem is shown to be isomorphic to that of the transonic flow of a compressible gas over a thin aerofoil. The non-dimensional drag exerted by the obstacle on the flow takes the form D(Gamma)M-5/3, where Gamma = (F - 1)M-2/3 is a transcritical similarity parameter and D is a function which depends on the shape of the 'equivalent aerofoil' specific to the obstacle. The theory is verified numerically by comparing results from a shock-capturing shallow-water model with corresponding solutions of the transonic small-disturbance equation, and is found to be generally accurate for M less than or similar to 0.4 and vertical bar Gamma vertical bar less than or similar to 1. In weakly dispersive flow the equivalent aerofoil becomes the boundary condition for the Kadomtsev-Petviashvili equation and (multiple) solitary waves replace hydraulic jumps in the resulting flow patterns.For Gamma greater than or similar to 1.5 the transcritical similarity theory is found to be inaccurate and, for small M, flow patterns are well described by a supercritical theory, in which the flow is determined by the linear solution near the obstacle. In this regime the drag is shown to be c(d)M(2)/(F root F-2 - 1), where c(d) is a constant dependent on the obstacle shape. Away from the obstacle, in non-dispersive flow the far-field behaviour is known to be described by the N-wave theory of Whitham and in dispersive flow by the Kortewegde Vries equation. In the latter case the number of emergent solitary waves in the wake is shown to be a function of A = 3M/(2 delta(2) root F-2 - 1), where delta is the ratio of the undisturbed layer depth to the radial scale of the obstacle

Transcritical rotating flow over topography

The flow of a one-and-a-half layer fluid over a three-dimensional obstacle of non-dimensional height M, relative to the lower layer depth, is investigated in the presence of rotation, the magnitude of which is measured by a non-dimensional parameter B (inverse Burger number). The transcritical regime in which the Froude number F, the ratio of the flow speed to the interfacial gravity wave speed, is close to unity is considered in the shallow-water (small-aspect-ratio) limit. For weakly rotating flow over a small isolated obstacle (M -> 0) a similarity theory is developed in which the behaviour is shown to depend on the parameters Gamma = (F - 1)M-2/3 and nu = (BM-1/3)-M-1/2. The flow pattern in this regime is determined by a nonlinear equation in which Gamma and nu appear explicitly, termed here the 'rotating transcritical small-disturbance equation' (rTSD equation, following the analogy with compressible gasdynamics). The rTSD equation is forced by 'equivalent aerofoil' boundary conditions specific to each obstacle. Several qualitatively new flow behaviours are exhibited, and the parameter reduction afforded by the theory allows a (Gamma, nu) regime diagram describing these behaviours to be constructed numerically. One important result is that, in a supercritical oncoming flow in the presence of sufficient rotation (nu greater than or similar to 2), hydraulic jumps can appear downstream of the obstacle even in the absence of an upstream jump. Rotation is found to have the general effect of increasing the amplitude of any existing downstream hydraulic jumps and reducing the lateral extent and amplitude of upstream jumps. Numerical results are compared with results from a shock-capturing shallow-water model, and the (Gamma, nu) regime diagram is found to give good qualitative and quantitative predictions of flow patterns at finite obstacle height (at least for M less than or similar to 0.4). Results are compared and contrasted with those for a two-dimensional obstacle or ridge, for which rotation also causes hydraulic jumps to form downstream of the obstacle and acts to attenuate upstream jumps

MicroRNA responses to acute resistance exercise protocols: a pilot study

INTRODUCTION: MicroRNAs (miRNAs) are non-coding RNAs that have an important role in regulating gene expression. Although circulating miRNAs are considered good markers of response to acute resistance training (RT) (1), change in expression according to the applied stimulus (e.g. high-intensity low-volume vs. low-intensity high-volume) has yet to be investigated. The aim of this study was therefore to evaluate the impact of RT protocols on circulating miRNA levels. We selected miRNA 29a, 128a, 486 as they have been previously shown to be implicated in skeletal muscle regeneration and structural adaptation (i.e. hypertrophy

Availability of supplies and motivations for accessing voluntary HIV counseling and testing services in Blantyre, Malawi

<p>Abstract</p> <p>Background</p> <p>HIV counseling and testing is an important intervention in the prevention, control and management of the human immunodeficiency virus (HIV). Counseling and testing can be an entry point for prevention, care and support. Knowledge of the quality of services and motivations for testing by individuals is important for effective understanding of the testing environment.</p> <p>Methods</p> <p>A cross sectional explorative study of clients accessing HIV voluntary counseling and testing (VCT) and counselors was conducted in 6 government health centers in Blantyre City, Malawi. We aimed to assess the availability of critical clinic supplies and identify the motivations of clients seeking counseling and testing services. We also aimed to identify the health professional cadres that were providing VCT in Blantyre city.</p> <p>Results</p> <p>102 VCT clients and 26 VCT counselors were interviewed. Among the VCT clients, 74% were <=29 years, 58.8% were females and only 7% reported no formal education. 42.2% were single, 45.1% married, 8.8% widowed and 3.9% divorced or separated. The primary reasons for seeking HIV counseling and testing were: recent knowledge about HIV (31.4%), current illness (22.5%), self-assessment of own behavior as risky (15.5%), suspecting sexual partner's infidelity (13.7%) and seeking HIV confirmatory test (9.8%) and other reasons (6.9%). Of the 26 VCT counselors, 14 were lay volunteers, 7 health surveillance assistants and 5 nurses. All except one had been trained specifically for HIV counseling and testing. All 6 facilities were conducting rapid HIV testing with same day test results provided to clients. Most of the supplies were considered adequate for testing.</p> <p>Conclusion</p> <p>HIV counseling and testing facilities were available in Blantyre city in all the six public health facilities assessed. The majority of counseling and testing clients were motivated by perceptions of being at risk of HIV infection. In a country with 12% of individuals 15 to 49 years infected, there is need to encourage testing among population groups that may not perceive themselves to be at risk of infection.</p

Neuropsychiatric manifestation of confusional psychosis due to Cryptococcus neoformans var. grubii in an apparently immunocompetent host: a case report

Cognitive disorders like dementia, delirium, depression, anxiety, psychosis and mania are the commonest neuropsychiatric manifestations. We discuss here a case of an adult women presenting with neuropsychiatric manifestations of confusional psychosis owing to Cryptococcosis. The principal cause was consequently established by culturing Cryptococcus neoformans from the cerebrospinal fluid confirmed as C. neoformans var. grubii (Serotype A) by genotypic methods. Antifungal therapy with IV Amphotericin B lead to sustained improvement and recovery of the patient from behavioural disorders. The case discussed here invokes the need for the vigilance it demands in delineating organic brain syndromes for a favourable treatment outcome

Cultural adaptation and psychometric evaluation of the Yoruba version of the Health Literacy Questionnaire

Background. Health literacy is an important multidimensional concept of public health concern and a determinant of health outcomes and access to healthcare which requires robust measurement. The objective of this study was to culturally adapt and establish the psychometric properties of the Yoruba version of the Health Literacy Questionnaire. Methods. A cross-sectional survey of Nigeria Yoruba speaking adults was conducted with the Health Literacy Questionnaire following its translation and adaptation. Data were subject to psychometric evaluation (confirmatory factor analysis, composite reliability, Cronbach’s alpha, intra class correlation) and association with sociodemographic variables. Results. A total of 258 adults with mean age 26.7 years participated in the study. The easiest scale to score highly was ‘Actively managing my health’ and hardest was ‘Ability to find good health information’ and ‘Navigating the healthcare system’. Six one-factor models fitted well without correlated residuals but the other three had a good fit after model modification. Composite reliability and Cronbach’s α of ≥0.7 were observed for all scales, suggesting good internal consistency of the scales. Test-retest reliability of the Yoruba translation of the Health Literacy Questionnaire was moderate to good in all scales, intra class correlation ranging from 0.66 to 0.76. Conclusion. The Health Literacy Questionnaire was successfully translated and culturally adapted and demonstrated good content and construct validity and high composite reliability. The Yoruba translation of the Health Literacy Questionnaire has the potential of being a useful clinical tool for the assessment of health literacy, especially among Yoruba speaking community of Nigeria. Thereby helping to improve the health outcomes through access to healthcare

Low pH immobilizes and kills human leukocytes and prevents transmission of cell-associated HIV in a mouse model

BACKGROUND: Both cell-associated and cell-free HIV virions are present in semen and cervical secretions of HIV-infected individuals. Thus, topical microbicides may need to inactivate both cell-associated and cell-free HIV to prevent sexual transmission of HIV/AIDS. To determine if the mild acidity of the healthy vagina and acid buffering microbicides would prevent transmission by HIV-infected leukocytes, we measured the effect of pH on leukocyte motility, viability and intracellular pH and tested the ability of an acidic buffering microbicide (BufferGel(®)) to prevent the transmission of cell-associated HIV in a HuPBL-SCID mouse model. METHODS: Human lymphocyte, monocyte, and macrophage motilities were measured as a function of time and pH using various acidifying agents. Lymphocyte and macrophage motilities were measured using video microscopy. Monocyte motility was measured using video microscopy and chemotactic chambers. Peripheral blood mononuclear cell (PBMC) viability and intracellular pH were determined as a function of time and pH using fluorescent dyes. HuPBL-SCID mice were pretreated with BufferGel, saline, or a control gel and challenged with HIV-1-infected human PBMCs. RESULTS: Progressive motility was completely abolished in all cell types between pH 5.5 and 6.0. Concomitantly, at and below pH 5.5, the intracellular pH of PBMCs dropped precipitously to match the extracellular medium and did not recover. After acidification with hydrochloric acid to pH 4.5 for 60 min, although completely immotile, 58% of PBMCs excluded ethidium homodimer-1 (dead-cell dye). In contrast, when acidified to this pH with BufferGel, a microbicide designed to maintain vaginal acidity in the presence of semen, only 4% excluded dye at 10 min and none excluded dye after 30 min. BufferGel significantly reduced transmission of HIV-1 in HuPBL-SCID mice (1 of 12 infected) compared to saline (12 of 12 infected) and a control gel (5 of 7 infected). CONCLUSION: These results suggest that physiologic or microbicide-induced acid immobilization and killing of infected white blood cells may be effective in preventing sexual transmission of cell-associated HIV

How does study quality affect the results of a diagnostic meta-analysis?

Background: The use of systematic literature review to inform evidence based practice in diagnostics is rapidly expanding. Although the primary diagnostic literature is extensive, studies are often of low methodological quality or poorly reported. There has been no rigorously evaluated, evidence based tool to assess the methodological quality of diagnostic studies. The primary objective of this study was to determine the extent to which variations in the quality of primary studies impact the results of a diagnostic meta-analysis and whether this differs with diagnostic test type. A secondary objective was to contribute to the evaluation of QUADAS, an evidence-based tool for the assessment of quality in diagnostic accuracy studies. Methods: This study was conducted as part of large systematic review of tests used in the diagnosis and further investigation of urinary tract infection (UTI) in children. All studies included in this review were assessed using QUADAS, an evidence-based tool for the assessment of quality in systematic reviews of diagnostic accuracy studies. The impact of individual components of QUADAS on a summary measure of diagnostic accuracy was investigated using regression analysis. The review divided the diagnosis and further investigation of UTI into the following three clinical stages: diagnosis of UTI, localisation of infection, and further investigation of the UTI. Each stage used different types of diagnostic test, which were considered to involve different quality concerns. Results: Many of the studies included in our review were poorly reported. The proportion of QUADAS items fulfilled was similar for studies in different sections of the review. However, as might be expected, the individual items fulfilled differed between the three clinical stages. Regression analysis found that different items showed a strong association with test performance for the different tests evaluated. These differences were observed both within and between the three clinical stages assessed by the review. The results of regression analyses were also affected by whether or not a weighting (by sample size) was applied. Our analysis was severely limited by the completeness of reporting and the differences between the index tests evaluated and the reference standards used to confirm diagnoses in the primary studies. Few tests were evaluated by sufficient studies to allow meaningful use of meta-analytic pooling and investigation of heterogeneity. This meant that further analysis to investigate heterogeneity could only be undertaken using a subset of studies, and that the findings are open to various interpretations. Conclusion: Further work is needed to investigate the influence of methodological quality on the results of diagnostic meta-analyses. Large data sets of well-reported primary studies are needed to address this question. Without significant improvements in the completeness of reporting of primary studies, progress in this area will be limited

Age-associated mitochondrial DNA mutations cause metabolic remodelling that contributes to accelerated intestinal tumorigenesis.

Oxidative phosphorylation (OXPHOS) defects caused by somatic mitochondrial DNA (mtDNA) mutations increase with age in human colorectal epithelium and are prevalent in colorectal tumours, but whether they actively contribute to tumorigenesis remains unknown. Here we demonstrate that mtDNA mutations causing OXPHOS defects are enriched during the human adenoma/carcinoma sequence, suggesting they may confer a metabolic advantage. To test this we deleted the tumour suppressor Apc in OXPHOS deficient intestinal stem cells in mice. The resulting tumours were larger than in control mice due to accelerated cell proliferation and reduced apoptosis. We show that both normal crypts and tumours undergo metabolic remodelling in response to OXPHOS deficiency by upregulating the de novo serine synthesis pathway (SSP). Moreover, normal human colonic crypts upregulate the SSP in response to OXPHOS deficiency prior to tumorigenesis. Our data show that age-associated OXPHOS deficiency causes metabolic remodelling that can functionally contribute to accelerated intestinal cancer development

Positive Interactions between Desert Granivores: Localized Facilitation of Harvester Ants by Kangaroo Rats

Facilitation, when one species enhances the environment or performance of another species, can be highly localized in space. While facilitation in plant communities has been intensely studied, the role of facilitation in shaping animal communities is less well understood. In the Chihuahuan Desert, both kangaroo rats and harvester ants depend on the abundant seeds of annual plants. Kangaroo rats, however, are hypothesized to facilitate harvester ants through soil disturbance and selective seed predation rather than competing with them. I used a spatially explicit approach to examine whether a positive or negative interaction exists between banner-tailed kangaroo rat (Dipodomys spectabilis) mounds and rough harvester ant (Pogonomyrmex rugosus) colonies. The presence of a scale-dependent interaction between mounds and colonies was tested by comparing fitted spatial point process models with and without interspecific effects. Also, the effect of proximity to a mound on colony mortality and spatial patterns of surviving colonies was examined. The spatial pattern of kangaroo rat mounds and harvester ant colonies was consistent with a positive interspecific interaction at small scales (<10 m). Mortality risk of vulnerable, recently founded harvester ant colonies was lower when located close to a kangaroo rat mound and proximity to a mound partly predicted the spatial pattern of surviving colonies. My findings support localized facilitation of harvester ants by kangaroo rats, likely mediated through ecosystem engineering and foraging effects on plant cover and composition. The scale-dependent effect of kangaroo rats on abiotic and biotic factors appears to result in greater founding and survivorship of young colonies near mounds. These results suggest that soil disturbance and foraging by rodents can have subtle impacts on the distribution and demography of other species