A.c.-impedance spectroscopy study of oxygen reduction at Nafion® coated gas-diffusion electrodes in sulphuric acid: Teflon loading and methanol cross-over effects

The kinetics of oxygen reduction have been studied at Nafion®-coated dual layer gas-diffusion electrodes at 60 °C in 2.5 M H₂SO₄. A.c. impedance and steady state galvanostatic measurements have been carried out on electrodes containing various PTFE loadings. A.c. impedance spectroscopy supplied information on charge transfer resistance, series resistance and double layer capacitance of electrodes during the oxygen reduction process. These parameters, together with those derived by d.c. measurements (i.e. Tafel slopes, charge transfer coefficient, etc.), allowed a better identification of the features governing the electrode efficiency and the reduction mechanism. The best electrode was found to be one containing 30% PTFE; this showed both the lowest charge transfer resistance and the lowest overpotential for oxygen reduction. This electrode also showed lower overpotential than the same uncoated electrode at low current densities. The poisoning effect by methanol has been also investigated. Upon addition of methanol to the solution, no change was observed in the reaction mechanism at low overpotentials. In contrast, a significant variation of the Tafel slope was observed at high overpotentials. This behaviour is interpreted in terms of the variation of Pt-O bond strength as a function of electrode potential.     

Intensive child-centered play therapy with child witnesses of domestic violence.

Examined the effectiveness of child-centered play therapy sessions every day for 2 wks as an intervention for child witnesses of domestic violence. 22 children (aged 4–10 yrs) participated. The analyses of covariance indicated that children in the experimental group experience a significant increase in self-concept, a significant decrease in external and total behavior problems, a significant increase in the play behavior of physical proximity to the therapist, and a significant increase in the play behavior of nurturing and creative play themes. The results support utilizing intensive play therapy to treat child witnesses of domestic violence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Steal phenomenon from mammary side branches: when does it occur?

BACKGROUND: The hemodynamic significance of patent mammary graft side branches is still controversial. This study was designed to evaluate the potential for flow steal of patent mammary side branches in different hemodynamic conditions. METHODS: Echo-Doppler measurement of mammary graft flow was performed at rest and after dipyridamole-induced coronary vasodilatation in 10 patients with angiographic demonstration of evident mammary graft side branches (study group) and in 10 matched control patients (control group). Concomitant thallium-201 myocardial scintigraphy was performed to assess the adequacy of mammary flow to the myocardial oxygen demand. Patients of the study group were also submitted to flow evaluation in condition of selective muscular or combined systemic and coronary relaxation. RESULTS: No difference in mammary flow and adequacy to myocardial oxygen demand was detected between patients of the study and control groups both at rest and after dipyridamole infusion. In patients with patent side branches the systolic-to-diastolic flow ratio was maintained in case of combined coronary and peripheral vasodilatation, whereas selective muscular relaxation led to an increase in the systolic and a reduction in the diastolic flow. CONCLUSIONS: Flow steal from patent mammary graft side branches is possible only in case of selective muscular vasodilatation. As this situation is unlikely to occur in the clinical setting, the potential for flow steal of mammary side branches in cardiac surgery patients seems to be minimal.     

Concept formation from design cases: why reusing experience and why not

This paper describes an environment that supports novice information systems designers in initial concept formation by organising design `cases' in evolving networks, automatically clustered by a neural agent to suggest generalisations of design patterns. Flexible reframing of the cases also supports creativity by uncovering less obvious but relevant design concepts. If the responsibility, of linking related design cases is distributed to a population of learners who contribute their cases and tentative generalisations, genetic techniques can be applied to sustain the evolution of the base of cases towards ontological forms that better guide and constrain the case reuse process, thus supporting knowledge transfer.     

Laparoscopic +proctopexy

BACKGROUND: Although not common, rectal prolapse in adults can often be a debilitating conditions. Its only effective treatment is surgical. Among the many procedures described for the treatment of rectal prolapse, abdominal rectopexy is one of the preferred. It consists of fixation of the rectum to the sacrum and does not require any intestinal resection or anastomosis. However, like all open abdominal surgery associated with a large incision this operation may result in significant morbidity which is exacerbated by the advanced age of the patient. METHODS: An abdominal rectopexy carried out completely laparoscopically is described. The rectum is fully mobilised down to the pelvic floor and then fixed to the sacrum employing a polypropylene mesh. The mesh is first stapled to the sacral hollow and then sutured on both sides of the rectum. Thus the mesh is wrapped around the lateral aspects of the rectum, but the anterior rectal wall is left free. Laparoscopic techniques have been applied to a wide range of benign and malignant colorectal procedures. RESULTS: However most of colorectal laparoscopic techniques involving bowel resection, are technically demanding and require often an abdominal incision to deliver the specimen and fashion the anastomosis. CONCLUSIONS: Without the need for bowel resection, the laparoscopic rectopexy may constitute an optimal application of laparoscopic colorectal techniques and may soon become the gold standard for the treatment of rectal prolapse.     

Influence of galanin and serotonin on the endocrine response to Hexarelin, a synthetic peptidyl GH-secretagogue, in normal women

BACKGROUND: Lack of information about the effect of insurance coverage on the demand for and use of smoking-cessation services has prevented widescale adoption of coverage for such services. METHODS: In a longitudinal, natural experiment, we compared the use and cost effectiveness of three forms of coverage with those of a standard form of coverage for smoking-cessation services that included a behavioral program and nicotine-replacement therapy. The study involved seven employers and a total of 90,005 adult enrollees. The standard plan offered 50 percent coverage of the behavioral program and full coverage of nicotine-replacement therapy. The other plans offered 50 percent coverage of both the behavioral program and nicotine-replacement therapy (reduced coverage), full coverage of the behavioral program and 50 percent coverage of nicotine-replacement therapy (flipped coverage), or full coverage of both the behavioral program and nicotine-replacement therapy. RESULTS: Estimated annual rates of use of smoking-cessation services ranged from 2.4 percent (among smokers with reduced coverage) to 10 percent (among those with full coverage). Smoking-cessation rates ranged from 28 percent (among users with full coverage) to 38 percent (among those with standard coverage). The estimated percentage of all smokers who would quit smoking per year as a result of using the services ranged from 0.7 percent (with reduced coverage) to 2.8 percent (with full coverage). The average cost to the health plan per user who quit smoking ranged from $797 (with standard coverage) to $1,171 (with full coverage). The annual cost per smoker ranged from $6 (with reduced coverage) to $33 (with full coverage). The annual cost per enrollee ranged from $0.89 (with reduced coverage) to $4.92 (with full coverage). CONCLUSIONS: Use of smoking-cessation services varies according to the extent of coverage, with the highest rates of use among smokers with full coverage. Although the rate of smoking cessation among the benefit users with full coverage was lower than the rates among users with plans requiring copayments, the effect on the overall prevalence of smoking was greater with full coverage than with the cost-sharing plans.     

Ultra-low drift microwave cryogenic oscillator

The operation of a microwave cryogenic sapphire resonator oscillator presenting an exceptional frequency stability for long integration times has been demonstrated. Based on a very simple design the 11.5 GHz oscillator presents a fractional frequency instability lower than 6/spl times/10/sup -14/ over one day.     

Cell proliferation and ploidy of human solid tumours: methodological experience with in vivo bromodeoxyuridine and DNA flow cytometry

The divalent cation selective ionophores A23187 and ionomycin were compared for their effects on the Ca2+ contents, nucleotide contents, and protein synthetic rates of several types of cultured cells. Both ionophores reduced amino acid incorporation by approximately 85% at low concentrations (50-300 nmol/L) in cultured mammalian cells without reducing ATP or GTP contents. At these concentrations A23187 and ionomycin each promoted substantial Ca2+ efflux, whereas at higher concentrations a large influx of the cation was observed. Ca2+ influx occurred at lower ionophore concentrations and to greater extents in C6 glioma and P3X63Ag8 myeloma than in GH3 pituitary cells. The ATP and GTP contents of the cells and their ability to adhere to growth surfaces declined sharply at ionophore concentrations producing increased Ca2+ influx. Prominent reductions of nucleotide contents occurred in EGTA-containing media that were further accentuated by extracellular Ca2+. Ionomycin produced more Ca2+ influx and nucleotide decline than comparable concentrations of A23187. The inhibition of amino acid incorporation and mobilization of cell-associated Ca2+ by ionomycin were readily reversed in GH3 cells by fatty acid-free bovine serum albumin, whereas the effects of A23187 were only partially reversed. Amino acid incorporation was further suppressed by ionophore concentrations depleting nucleotide contents. Mitochondrial uncouplers potentiated Ca2+ accumulation in response to both ionophores. At cytotoxic concentrations Lubrol PX abolished protein synthesis but did not cause Ca2+ influx. Nucleotide depletion at high ionophore concentrations is proposed to result from increased plasmalemmal Ca2+-ATPase activity and dissipation of mitochondrial proton gradients and to cause intracellular Ca2+ accumulation. Increased Ca2+ contents in response to Ca2+ ionophores are proposed as an indicator of ionophore-induced cytotoxicity.