4,273 research outputs found

    The Physiological Basis for Altered Na\u3csup\u3e+\u3c/sup\u3e and Cl\u3csup\u3e-\u3c/sup\u3e Movement Across the Gills of Rainbow Trout (\u3cem\u3eOncorhynchus mykiss\u3c/em\u3e) in Alkaline (pH=9.5) Water

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    To test the hypothesis that internal ion imbalances at high pH are caused by altered branchial ion transporting capacity and permeability, radiotracers (24Na+ and 36Cl-) were used to measure ion movements across the gills of intact rainbow trout (Oncorhynchus mykiss) during 3 d exposure to pH 9.5. At control pH (pH 8.0), the trout were in net ion balance, but by 8 h at high pH, 60%–70% reductions in Cl- influx (Cl) and Na+ influx (JNa/in) led to net Cl- and Na+ losses of -200 µmol kg-1 h-1. Outflux (diffusive efflux plus renal ion losses) was not initially altered. By 72 h, net Cl- balance was reestablished because of a restoration of JCl/in. Although JNa/in remained 50% lower at this time, counterbalancing reductions in Na+ outflux restored net Na+ balance. One-substrate ion-uptake kinetics analyses indicated that reduced ion influx after 8 h at pH 9.5 was caused by 50% decreases in Cl- and Na+ maximal transport rates (JCl/max, JNa/max), likely reflecting decreased numbers of functional transport sites. Two-substrate kinetic analyses indicated that reduced internal HCO3- and H+ supply for respective branchial Cl-/base and Na+/acid transport systems also contributed to lower JCl/in and, to a lesser extent, lower JNa/in at pH 9.5. Recovery in in of JCl/in after 3 d accounted for restoration of Cl- balance and max likely reflected increased numbers of transport sites. In contrast, JNa/in remained 33% lower after 3 d, but a lower affinity of the max gills for Na+ (fourfold greater KNa/m) accounted for the chronic m reduction in Na+ influx at pH 9.5. Thus, reestablishment of Cl- uptake capacity and counterbalancing reductions in Na+ outflux allows rainbow trout to reestablish net ion balance in alkaline waters

    Integrated multilevel converter and battery management

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    A cascaded H-bridge multilevel converter is proposed as a BLDC drive incorporating real-time battery management. Intelligent H-bridges are used to monitor battery cells whilst simultaneously increasing their performance by reducing the variation between cells and controlling their discharge profiles

    Home dialysis-an international perspective.

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    Background. There is strong evidence from a range of long-term conditions of improved outcomes where patients are involved in self-management. Against this background, the international trend for home dialysis continues to decline, with centre-based haemodialysis continuing its dominance. Methods. An opinion-based commentary exploring practice patterns and drivers for home dialysis internationally. Data are drawn from a number of sources including the 2010 United States Renal Data System report. Results. Drivers behind the use of home dialysis are complex including factors relating to the patient and their carers, health care team, health care system, geography and cultural factors. There are important examples where local champions or public health initiatives have had a positive impact on the use of home dialysis; however, in many settings significant barriers remain. Better systems for giving patient information, shared decision making and involving patients in their own care may have the potential to act as a driver for change. Conclusion. Centre-based haemodialysis continues to dominate renal replacement therapy internationally with notable exceptions. Such dominance suggests that most patients worldwide do not get much choice when it comes to modality selection

    Hardware-in-the-loop tuning of a feedback controller for a buck converter using a GA

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    This paper presents a methodology for tuning a PID-based feedback controller for a buck converter using the ITAE controller performance index. The controller parameters are optimized to ensure that a reasonable transient response can be achieved whilst retaining stable operation. Experimental results demonstrate the versatility of the on-line tuning methodology

    A cascaded H-bridge BLDC drive incorporating battery management

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    A multilevel BLDC drive is proposed using cascaded H-bridges with isolated sources to provide superior output waveforms and reduced current ripple whilst incorporating observer based SoC estimation. Energy management, based on SoC, is incorporated to improve battery performance, reduce variation between cells and to control charge/discharge profiles

    Exact norm-conserving stochastic time-dependent Hartree-Fock

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    We derive an exact single-body decomposition of the time-dependent Schroedinger equation for N pairwise-interacting fermions. Each fermion obeys a stochastic time-dependent norm-preserving wave equation. As a first test of the method we calculate the low energy spectrum of Helium. An extension of the method to bosons is outlined.Comment: 21 pages, 3 figures, LaTeX fil

    'Minilivestock' Farming : Who is Farming Edible Insects in Europe and North America?

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    This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.Peer reviewedPostprintPostprin
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