HYPOFIBRINOGENAEMIA

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Evaluation of concentrated space solar arrays using computer modeling

A general approach is developed for predicting the power output of a concentrator enhanced photovoltaic space array. A ray trace routine determines the concentrator intensity arriving at each solar cell. An iterative calculation determines the cell's operating temperature since cell temperature and cell efficiency are functions of one another. The end result of the iterative calculation is that the individual cell's power output is determined as a function of temperature and intensity. Circuit output is predicted by combining the individual cell outputs using the single diode model of a solar cell. Concentrated array characteristics such as uniformity of intensity and operating temperature at various points across the array are examined using computer modeling techniques. An illustrative example is given showing how the output of an array can be enhanced using solar concentration techniques

Cardio-Protection Afforded by Β-Blockade Is Maintained During Resistance Exercise

Objectives Whether or not the cardio-protective effect of β-adrenergic blockade is retained during resistance exercise has not been systematically evaluated. Therefore the purpose of this study was to measure selected cardiorespiratory responses to isometric exercise involving hand-gripping, single-leg extension, or double-leg dead-lift, under placebo (control), β1-selective (atenolol), and non-selective (propranolol) adrenergic blockade conditions. Design Eleven young male adults were evaluated in a randomized, double-blinded, repeated measures study design and performed all three exercise modalities at 30% of maximal voluntary contraction under placebo, atenolol and propranolol conditions. Methods Heart rate, systolic and diastolic blood pressure, rate-pressure product, oxygen uptake, cardiac output, stroke volume and total peripheral resistance were directly measured or calculated at rest and during the third minute of each of the three exercise modes. Results Irrespective of drug condition, a graded pressor response was observed going from rest to exercise so that rest \u3c handgrip \u3c leg extension \u3c dead-lift for heart rate, systolic and diastolic blood pressures, rate-pressure product and oxygen uptake (p \u3c 0.05 for all). Cardiac output only increased with the dead-lift mode of exercise (p \u3c 0.01). Importantly β-adrenergic blockade with either atenolol or propranolol similarly attenuated the rise in heart rate, and systolic blood pressure; thus rate-pressure product demonstrated a mode-of-exercise by drug interaction effect (p \u3c 0.001) with the greatest reductions seen with the dead-lift procedure. Conclusions The findings indicate that cardio-protection afforded by selective or non-selective β-blockade at rest is preserved during isometric exercise and even enhanced once heart rate increases above 100 beats min−1

The Impact of Lateral Gene Transfer in Chlamydia

Lateral gene transfer (LGT) facilitates many processes in bacterial ecology and pathogenesis, especially regarding pathogen evolution and the spread of antibiotic resistance across species. The obligate intracellular chlamydiae, which cause a range of diseases in humans and animals, were historically thought to be highly deficient in this process. However, research over the past few decades has demonstrated that this was not the case. The first reports of homologous recombination in the Chlamydiaceae family were published in the early 1990s. Later, the advent of whole-genome sequencing uncovered clear evidence for LGT in the evolution of the Chlamydiaceae, although the acquisition of tetracycline resistance in Chlamydia (C.) suis is the only recent instance of interphylum LGT. In contrast, genome and in vitro studies have shown that intraspecies DNA exchange occurs frequently and can even cross species barriers between closely related chlamydiae, such as between C. trachomatis, C. muridarum, and C. suis. Additionally, whole-genome analysis led to the identification of various DNA repair and recombination systems in C. trachomatis, but the exact machinery of DNA uptake and homologous recombination in the chlamydiae has yet to be fully elucidated. Here, we reviewed the current state of knowledge concerning LGT in Chlamydia by focusing on the effect of homologous recombination on the chlamydial genome, the recombination machinery, and its potential as a genetic tool for Chlamydia

Pre-treatment of surface waters for ceramic microfiltration

The influence of pre-treatment on the suppression of irreversible (IR) fouling of ceramic membranes challenged with three UK surface waters has been studied at pilot scale. An initial scoping study compared the efficacy of suspended ion exchange (SIX) and clarification (coagulation followed by sludge blanket clarification) individually and in combination. Direct membrane filtration following in-line coagulation (ILCA) was also investigated with and without SIX. The impact on the various organic fractions, specifically high molecular weight (HMW) biopolymers (BPs) and humic substances (HSs), and lower molecular weight (LMW) building blocks (BBs) and neutrals, was studied using liquid chromatography-organic carbon detection (LC-OCD). Results revealed SIX and coagulation to preferentially remove the LMW and HMW organic fractions respectively. Residual HMW organic matter (primarily BPs) following SIX pre-treatment were retained by the membrane which led to rapid irreversible fouling. Coagulation pre-treatment provided stable membrane operation and the residual LMW organics were not significantly retained by the membrane. Combining clarification and SIX resulted in significantly increased removal of organics and lower membrane fouling rates. Tests performed using SIX and ILCA revealed high dissolved organic carbon (DOC) removal compared to SIX with clarification. However, unlike the case for clarification with SIX, the addition of SIX to optimised ILCA dosing offered no additional suppression of membrane fouling compared to ILCA alone. Optimised ILCA pretreatment led to very low IR fouling rates of <0.3 kPa/day trans-membrane pressure, despite highly challenging operating conditions of elevated fluxes (185 L m−2 h−1) and highly variable feedwater dissolved organic carbon concentrations

Virulence factors of Aeromonas salmonicida and their interaction with the salmonid host

Selected secreted and cellular virulence factors of Aeromonas salmonicida were examined. A protocol was developed for the separation of two secreted proteases (P1 and P2 protease), and a trout erythrocyte specific hemolysin (T-lysin) from supernatants of cultures of the bacterium. Distinctions between the proteases were demonstrated using molecular weight determinations, substrate specificities, sensitivity to chemical protease inhibitor sensitivities, and polyacrylamide gel electrophoresis using gels containing protease substrates (G-PAGE). P1, but not P2, protease was detected in G-PAGE analyses of protease from lesions of coho salmon (Oncorhynchus kisutch) infected by injection. Other proteases of apparent host origin were also detected in these assays. Analysis of the T-lysin demonstrated that although the bacterium produced high titers of the enzyme in vitro, no hemolytic activity was detected in vivo nor in cultures grown in salmonid sera. Subsequent experiments demonstrated that salmonid sera possess an inhibitor of hemolysis capable of protecting erythrocytes from enzymatic or chemical lysis. The inhibitor was partially purified using molecular sieve chromatography and preparative isoelectric focusing. Analysis of P1 protease, P2 protease, and T-lysin production was continued by examining their production in the presence of salmonid sera and in the presence of high concentrations of selected salts added to brain heart infusion broth (BHI). The spectrum of proteases produced in serum was similar to the spectrum produced in BHI. However, a larger phenylmethylsufonyl fluoride sensitive fraction was detected in supernatants from bacterial cells grown in serum. Analysis of supernatants from the cultures grown in high salts indicated that P1 protease and T-lysin production were inhibited by these salts but P2 protease production was not. Growth in high concentrations of magnesium salts also affected the cellular morphology of the bacterium and this effect was associated with the presence of an outer membrane protein layer, the A layer. Four monoclonal antibodies (Mabs) were produced with specificity towards A. salmonicida lipopolysaccharide (LPS). These Mabs were used to identify two distinct epitopes on LPS and to show that the presence of each epitope varied among different strains. The antibodies were also used to demonstrate the difference in the host response of rabbits and rainbow trout (Oncorhynchus mykiss) to A. salmonicida