Fatigue testing a plurality of test specimens and method

Described is a fatigue testing apparatus for simultaneously subjecting a plurality of material test specimens to cyclical tension loading to determine the fatigue strength of the material. The fatigue testing apparatus includes a pulling head having cylinders defined therein which carry reciprocating pistons. The reciprocation of the pistons is determined by cyclical supplies of pressurized fluid to the cylinders. Piston rods extend from the pistons through the pulling head and are attachable to one end of the test specimens, the other end of the test specimens being attachable to a fixed base, causing test specimens attached between the piston rods and the base to be subjected to cyclical tension loading. Because all the cylinders share a common pressurized fluid supply, the breaking of a test specimen does not substantially affect the pressure of the fluid supplied to the other cylinders nor the tension applied to the other test specimens

Immunosuppressive effect and global dysregulation of blood transcriptome in response to psychosocial stress in vervet monkeys (Chlorocebus sabaeus).

Psychosocial stressors - life events that challenge social support and relationships - represent powerful risk factors for human disease; included amongst these events are relocation, isolation and displacement. To evaluate the impact of a controlled psychosocial stressor on physiology and underlying molecular pathways, we longitudinally studied the influence of a 28-day period of quarantine on biomarkers of immune signalling, microbial translocation, glycaemic health and blood transcriptome in the wild-born vervet monkey. This event caused a coordinated, mostly transient, reduction of circulating levels of nine immune signalling molecules. These were paralleled by a massive dysregulation of blood transcriptome, including genes implicated in chronic pathologies and immune functions. Immune and inflammatory functions were enriched among the genes downregulated in response to stress. An upregulation of genes involved in blood coagulation, platelet activation was characteristic of the rapid response to stress induction. Stress also decreased neutrophils and increased CD4 + T cell proportions in blood. This model of psychosocial stress, characterised by an immune dysregulation at the transcriptomic, molecular and cellular levels, creates opportunities to uncover the underlying mechanisms of stress-related diseases with an immune component, including cardiovascular diseases and susceptibility to infections

The development of a sub-atmospheric two-phase thermosyphon natural gas preheater using a lumped capacitance model and comparison with experimental results

The pre-heating of natural gas supplied to both domestic and industrial use is required to counteract the Joule–Thomson effect due to pressure reduction. Most existing pre-heaters are in the form of water bath heaters, where both the burner and exchanger are immersed in a closed water tank. These systems usually have a low efficiency, and as a result of thermal inertia have a long time lag to accommodate changes in Natural Gas (NG) mass flow rates. In this paper, the two-phase thermosyphon theory is implemented in a sub-atmospheric context to design and study a new preheating system in a transient fashion. This system is partially vacuumed (absolute pressure of 2 kPa) to lower the temperature operation range to reduce the required working fluid volume, hence reduce the required energy and improve the response time. The transient numerical model is based on a lumped capacitance method, and the full system is solved by using a fourth order Runge–Kutta method. The numerical model is validated through comparison with experimental results. Minimum efficiency of 68% has been achieved in some tests, whilst maximum efficiency of 80% in other tests. Simulations of the thermosyphon preheater system have been performed to analyse the effect of changing the working fluid volume and composition

Displaced geostationary orbit design using hybrid sail propulsion

Because of an increase in the number of geostationary spacecraft and the limits imposed by east–west spacing requirements, the geostationary orbit is becoming congested. To increase its capacity, this paper proposes to create new geostationary slots by displacing the geostationary orbit either out of or in the equatorial plane by means of hybrid solar sail and solar electric propulsion. To minimize propellant consumption, optimal steering laws for the solar sail and solar-electric-propulsion thrust vectors are derived and the performance in terms of mission lifetime is assessed. For comparison, similar analyses are performed for conventional propulsion, including impulsive and pure solar electric propulsion. It is shown that hybrid sails outperform these propulsion techniques and that out-of-plane displacements outperform in-plane displacements. The out-of-plane case is therefore further investigated in a spacecraft mass budget to determine the payload mass capacity. Finally, two transfers that enable a further improvement of the performance of hybrid sails for the out-of-plane case are optimized using a direct pseudospectral method: a seasonal transit between orbits displaced above and below the equatorial plane and a transit to a parking orbit when geostationary coverage is not needed. Both transfers are shown to require only a modest propellant budget, outweighing the improvements they can establish

Using social practice theory in measuring perceived stigma among female sex workers in Mombasa, Kenya

Background Perceived stigma is a complex societal phenomenon that is harboured especially by female sex workers because of the interplay of a myriad of factors. As such, a precise measure of the contribution of different social practices and characteristics is necessary for both understanding and intervening in matters related to perceived stigma. We developed a Perceived Stigma Index that measures the factors that greatly contribute to the stigma among sex workers in Kenya, and thereby inform a framework for future interventions. Methods Social Practice Theory was adopted in the development of the Perceived Stigma Index in which three social domains were extracted from data collected in the WHISPER or SHOUT study conducted among female sex workers (FSW), aged 16–35 years in Mombasa, Kenya. The three domains included: Social demographics, Relationship Control and Sexual and Gender-based Violence, and Society awareness of sexual and reproductive history. The factor assessment entailed Exploratory Factor Analysis (EFA), Confirmatory Factor Analysis (CFA), and the internal consistency of the index was measured using Cronbach’s alpha coefficient. Results We developed a perceived stigma index to measure perceived stigma among 882 FSWs with a median age of 26 years. A Cronbach’s alpha coefficient of 0.86 (95% confidence interval (CI) 0.85–0.88) was obtained as a measure of the internal consistency of our index using the Social Practice Theory. In regression analysis, we identified three major factors that contribute to the perceived stigma and consists of : (i) income and family support (β = 1.69; 95% CI); (ii) society’s awareness of the sex workers’ sexual and reproductive history (β = 3.54; 95% CI); and (iii) different forms of relationship control e.g. physical abuse (β = 1.48; 95%CI that propagate the perceived stigma among the FSWs. Conclusion Social practice theory has solid properties that support and capture the multi-dimensional nature of perceived stigma. The findings support the fact that social practices contribute or provoke this fear of being discriminated against. Thus, in offering interventions to curb perceived stigma, focus should fall on the education of the society on the importance of acceptance and integration of the FSWs as part of the society and the eradication of sexual and gender based violence meted out on them

Gravitational quasinormal modes for Anti-de Sitter black holes

Quasinormal mode spectra for gravitational perturbations of black holes in four dimensional de Sitter and anti-de Sitter space are investigated. The anti-de Sitter case is relevant to the ADS-CFT correspondence in superstring theory. The ADS-CFT correspondence suggests a prefered set of boundary conditions.Comment: 12 pages, 6 figures in ReVTe

Parvovirus B19 infection and severe anaemia in Kenyan children: a retrospective case control study

Background: During acute Human parvovirus B19 (B19) infection a transient reduction in blood haemoglobin concentration is induced, due to a 5-7 day cessation of red cell production. This can precipitate severe anaemia in subjects with a range of pre-existing conditions. Of the disease markers that occur during B19 infection, high IgM levels occur closest in time to the maximum reduction in haemoglobin concentration. Previous studies of the contribution of B19 to severe anaemia among young children in Africa have yielded varied results. This retrospective case/control study seeks to ascertain the proportion of severe anaemia cases precipitated by B19 among young children admitted to a Kenyan district hospital.Methods: Archival blood samples from 264 children under 6 years with severe anaemia admitted to a Kenyan District Hospital, between 1999 and 2004, and 264 matched controls, were tested for B19 IgM by Enzyme Immunosorbent Assay and 198 of these pairs were tested for B19 DNA by PCR. 536 samples were also tested for the presence of B19 IgG.Results: 7 (2.7%) cases and 0 (0%) controls had high B19 IgM levels (Optical Density > 5 x cut-off value) (McNemar's exact test p = 0.01563), indicating a significant association with severe anaemia. The majority of strongly IgM positive cases occurred in 2003.10/264 (3.7%) cases compared to 5/264 (1.9%) controls tested positive for B19 IgM. This difference was not statistically significant, odds ratio (OR) = 2.00 (CI95 [0.62, 6.06], McNemar's exact test p = 0.3018. There was no significant difference between cases and controls in the B19 IgG (35 (14.8%) vs 32 (13.6%)), OR = 1.103 (CI95 [0.66, 1.89], McNemar's exact test, p = 0.7982), or the detection of the B19 DNA (6 (3.0%) vs 5 (2.5%)), OR = 1.2 (CI95 [0.33, 4.01], McNemar's exact test p = 1).Conclusions: High B19 IgM levels were significantly associated with severe anaemia, being found only among the cases. This suggests that 7/264 (2.7%) of cases of severe anaemia in the population of children admitted to KDH were precipitated by B19. While this is a relatively small proportion, this has to be evaluated in the light of the IgG data that shows that less than 15% of children in the study were exposed to B19, a figure much lower than reported in other tropical areas

Treatment with ETC-1002 alone and in combination with ezetimibe lowers LDL cholesterol in hypercholesterolemic patients with or without statin intolerance

BackgroundETC-1002 is an oral, once-daily, first-in-class medication being developed to treat hypercholesterolemia.ObjectivesTo compare 2 doses of ETC-1002, alone or combined with ezetimibe 10 mg (EZE), vs EZE monotherapy for lowering low-density lipoprotein cholesterol (LDL-C).MethodsThis phase 2b, multicenter, double-blind trial-evaluated hypercholesterolemic patients (LDL-C, 130 to 220 mg/dL) with (n = 177) or without (n = 171) muscle-related intolerance to ≥2 statins; 1 at lowest approved dose. Subjects were randomized to 12-week treatment with ETC-1002 120 mg or ETC-1002 180 mg alone, EZE alone, ETC-1002 120 mg plus EZE, or ETC-1002 180 mg plus EZE.ResultsEZE alone lowered LDL-C by 21%, whereas ETC-1002 monotherapy with 120 mg or 180 mg reduced LDL-C by 27% (P = .0008 vs EZE) and 30% (P < .0001 vs EZE), respectively. The combination of ETC-1002, 120 mg or 180 mg plus EZE reduced LDL-C by 43% and 48%, respectively (both P < .0001 vs EZE). ETC-1002 alone or combined with EZE also reduced non–high-density lipoprotein cholesterol, total cholesterol, apolipoprotein B, LDL particle number, and high-sensitivity C-reactive protein compared with EZE alone. Across all treatment groups, statin-intolerant patients reported more muscle-related adverse events than did statin-tolerant patients. ETC-1002 was safe and well tolerated, and rates of muscle-related adverse events were similar in all treatment groups.ConclusionsIn patients with and without statin intolerance, daily treatment with ETC-1002 120 mg and 180 mg alone or with EZE reduced LDL-C more than EZE alone and had a similar tolerability profile (NCT01941836)

Role of BMI in the Association of the TCF7L2 rs7903146 Variant with Coronary Heart Disease: The Atherosclerosis Risk in Communities (ARIC) Study

We examined the association of variation in the type 2 diabetes risk-conferring TCF7L2 gene with the risk of incident coronary heart disease (CHD) among the lean, overweight, and obese members of the Atherosclerosis Risk in Communities (ARIC) Study cohort. Cox proportional hazard regression analyses were performed using a general model, with the major homozygote as the reference category. For 9,865 whites, a significant increase in the risk of CHD was seen only among lean ( BMI < 25 kg/m2) individuals homozygous for the T allele of the TCF7L2 rs7903146 gene risk variant (hazard ratio 1.42; 95% CI 1.03,1.97; P = .01). No association was found among 3,631 blacks, regardless of BMI status. An attenuated hazard ratio was observed among the nondiabetic ARIC cohort members. This study suggests that body mass modifies the association of the TCF7L2 rs7903146 T allele with CHD risk