85 research outputs found

    Assessment van Kinderen en jongeren: noodzaak om de blik te verruimen

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    Het onderwijs wordt geconfrnteerd met het dilemma om deprstaties en rendement van leerlingen te verhogen en anderzids ook iets te doen voor een groelend aantal uitvallers of onderpresteerders. Het Daffodil.project is een Europees Comenius- project is een Europees Comenius_multilateral samenwerkingsproject met partners uit 7 landen (Belgie, Hongarije, Zweden,Portugal, Noorwegen, Roemenie en de Britse Maagdeneilanden)met als doel een model te ontwikkelen dat bruikbaar is om het functioneren van kinderen met een probleem beter in kaart te brege

    Towards an understanding of induced-charge electrokinetics at large applied voltages in concentrated solutions

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    The venerable theory of electrokinetic phenomena rests on the hypothesis of a dilute solution of point-like ions in quasi-equilibrium with a weakly charged surface, whose potential relative to the bulk is of order the thermal voltage (kT/e ≈ 25 mV at room temperature). In nonlinear electrokinetic phenomena, such as AC or induced-charge electro-osmosis (ACEO, ICEO) and induced-charge electrophoresis (ICEP), several V ≈ 100 kT/e are applied to polarizable surfaces in microscopic geometries, and the resulting electric fields and induced surface charges are large enough to violate the assumptions of the classical theory. In this article, we review the experimental and theoretical literatures, highlight discrepancies between theory and experiment, introduce possible modifications of the theory, and analyze their consequences. We argue that, in response to a large applied voltage, the “compact layer” and “shear plane” effectively advance into the liquid, due to the crowding of counterions. Using simple continuum models, we predict two general trends at large voltages: (i) ionic crowding against a blocking surface expands the diffuse double layer and thus decreases its differential capacitance, and (ii) a charge-induced viscosity increase near the surface reduces the electro-osmotic mobility; each trend is enhanced by dielectric saturation. The first effect is able to predict high-frequency flow reversal in ACEO pumps, while the second may explain the decay of ICEO flow with increasing salt concentration. Through several colloidal examples, such as ICEP of an uncharged metal sphere in an asymmetric electrolyte, we show that nonlinear electrokinetic phenomena are generally ion-specific. Similar theoretical issues arise in nanofluidics (due to confinement) and ionic liquids (due to the lack of solvent), so the paper concludes with a general framework of modified electrokinetic equations for finite-sized ions.National Science Foundation (U.S.) (contract DMS-0707641

    Recommendations for active correction of hypernatremia in volume-resuscitated shock or sepsis patients should be taken with a grain of salt: A systematic review

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    Background: Healthcare-acquired hypernatremia (serum sodium >145 mEq/dL) is common among critically ill and other hospitalized patients and is usually treated with hypotonic fluid and/or diuretics to correct a “free water deficit.� However, many hypernatremic patients are eu- or hypervolemic, and an evolving body of literature emphasizes the importance of rapidly returning critically ill patients to a neutral fluid balance after resuscitation. Objective: We searched for any randomized- or observational-controlled studies evaluating the impact of active interventions intended to correct hypernatremia to eunatremia on any outcome in volume-resuscitated patients with shock and/or sepsis. Data sources: We performed a systematic literature search with studies identified by searching MEDLINE, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, ClinicalTrials.gov, IndexCatalogue of the Library of the Surgeon General’s Office, DARE (Database of Reviews of Effects), and CINAHL and scanning reference lists of relevant articles with abstracts published in English. Data synthesis: We found no randomized- or observational-controlled trials measuring the impact of active correction of hypernatremia on any outcome in resuscitated patients. Conclusion: Recommendations for active correction of hypernatremia in resuscitated patients with sepsis or shock are unsupported by clinical research acceptable by modern evidence standards.ECU Open Access Publishing Support Fun

    Rapid effects of dietary fish oil on peroxisomes in mouse liver

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    We investigated hepatic catalase activity, and morphologic and morphometric alterations of hepatocellular peroxisomes after catalase cytochemistry, in mice given a diet supplemented with 10% Beromegan(R), a commercial fish oil preparation, for up to three days. Fish oil is rich in docosahexaenoic acid (C22:6 (n-3)) and in eicosapentaenoic acid (20:5 (n-3)). Hepatic catalase activity showed a gradual increase in mice fed this diet, being significantly increased (136+/-10 U(B)/g liver) after three days when compared top controls (85+/-11 U(B)/g liver). Light microscopy indicated an increase in peroxisomal staining and peroxisomal proliferation. The latter observation was confirmed by ultrastructural morphometry: number, volume density and surface density of the peroxisomes were more than doubled after a three day diet containing fish oil. Peroxisomal size was not changed. These alterations are suggestive for an increased peroxisomal metabolism induced by a diet rich in poly-unsaturated fatty acids
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