825 research outputs found

    Organ Quality as a Complicating Factor in Proposed Systems of Inducements for Organ Donation

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    En typisk funktion pÄ startsidan till mÄnga webbportaler Àr den webbdel som presenterar exempelvis desenaste blogginlÀggen, nyheterna eller hÀndelserna som har lagts till pÄ webbplatsen. Dessa funktioner ÀrkÀnda som aggreggeringswebbdelar. Eftersom startsidan Àr den sida som besöks mest jÀmfört med alla andrawebbsidor i portalen innebÀr det i sin tur att denna funktion utnyttjas vÀldigt ofta.Detta arbete syftar till att finna ett antal olika metoder som kan anvÀndas för att uppnÄ denna funktion ochatt ta reda pÄ hur vÀl dessa webbdelar presterar.Denna rapport presenterar bÄde de olika metoder som fanns och resultaten pÄ en systematisk testning avdessa. Resultaten av testerna presenteras pÄ ett överskÄdligt sÀtt.Slutligen dras slutsatser angÄende resultaten. Resultaten föresprÄkar inte en specifik metod, den metod somlÀmpar sig bÀst för varje enskild sammanhang avgörs till största del av andra faktorer sÄsom frekvens avbesökare eller Àndringar pÄ innehÄllet som metoden söker igenom

    Climatic changes resulting from mass extinctions at the K-T boundary (and other bio-events)

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    The mass extinctions at the Cretaceous-Tertiary (K-T) boundary include about 90 percent of marine calcareous nannoplankton (coccoliths), and carbon-isotope data show that marine primary productivity was drastically reduced for about 500,000 years after the boundary event, the so-called Strangelove Ocean effect. One result of the elimination of most marine phytoplankton would have been a severe reduction in production of dimethyl sulfide (DMS), a biogenic gas that is believed to be the major precursor of cloud condensation nuclei (CCN) over the oceans. A drastic reduction in marine CCN should lead to a cloud canopy with significantly lower reflectivity, and hence cause a significant warming at the earth's surface. Calculations suggest that, all other things being held constant, a reduction in CCN of more than 80 percent (a reasonable value for the K-T extinctions) could have produced a rapid global warming of 6 C or more. Oxygen-isotope analyses of marine sediments, and other kinds of paleoclimatic data, have provided for a marked warming, and a general instability of climate coincident with the killoff of marine plankton at the K-T boundary. Similar reductions in phytoplankton abundance at other boundaries, as indicated by marked shifts in carbon-isotope curves, suggest that severe temperature changes may have accompanied other mass extinctions, and raises the intriguing possibility that the extinction events themselves could have contributed to the climatic instabilities at critical bio-events in the geologic record

    Center differences in model for end‐stage liver disease exceptions: Fairness, local culture, and norms of practice

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101873/1/lt23736.pd

    Unfair Priority for HCC: A Problem Whose Ideal Solution Remains Unsolved

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    Received 01 April 2010, revised 22 April 2010 and accepted for publication 29 April 2010Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79265/1/j.1600-6143.2010.03154.x.pd

    Polarization-dependence of palladium deposition on ferroelectric lithium niobate (0001) surfaces

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    We investigate the effect of ferroelectric polarization direction on the geometric properties of Pd deposited on the positive and negative surfaces of LiNbO3_3 (0001). We predict preferred geometries and diffusion properties of small Pd clusters using density functional theory, and use these calculations as the basis for kinetic Monte Carlo simulations of Pd deposition on a larger scale. Our results show that on the positive surface, Pd atoms favor a clustered configuration, while on the negative surface, Pd atoms are adsorbed in a more dispersed pattern due to suppression of diffusion and agglomeration. This suggests that the effect of LiNbO3_3 polarization direction on the catalytic activity of Pd [J. Phys. Chem. \textbf{88}, 1148 (1984)] is due, at least in part, to differences in adsorption geometry. Further investigations using these methods can aid the search for catalysts whose activities switch reversibly with the polarization of their ferroelectric substrates

    Patient‐centered liver transplantation

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/133603/1/cld564.pd

    Urgency, utility, and time horizon of transplant benefit

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110847/1/lt24082.pd

    Quantification of transport across the boundary of the lower stratospheric vortex during Arctic winter 2002/2003

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    Strong perturbations of the Arctic stratosphere during the winter 2002/2003 by planetary waves led to enhanced stretching and folding of the vortex. On two occasions the vortex in the lower stratosphere split into two secondary vortices that re-merged after some days. As a result of these strong disturbances the role of transport in and out of the vortex was stronger than usual. An advection and mixing simulation with the Chemical Lagrangian Model of the Stratosphere (CLaMS) utilising a suite of inert tracers tagging the original position of the air masses has been carried out. The results show a variety of synoptic and small scale features in the vicinity of the vortex boundary, especially long filaments peeling off the vortex edge and being slowly mixed into the mid latitude environment. The vortex folding events, followed by re-merging of different parts of the vortex led to strong filamentation of the vortex interior. During January, February, and March 2003 flights of the Russian high-altitude aircraft Geophysica were performed in order to probe the vortex, filaments and in one case the merging zone between the secondary vortices. Comparisons between CLaMS results and observations obtained from the Geophysica flights show in general good agreement. Several areas affected by both transport and strong mixing could be identified, allowing explanation of many of the structures observed during the flights. Furthermore, the CLaMS simulations allow for a quantification of the air mass exchange between mid latitudes and the vortex interior. The simulation suggests that after the formation of the vortex was completed, its interior remaind relatively undisturbed. Only during the two re-merging events were substantial amounts of extra-vortex air transported into the polar vortex. When in March the vortex starts weakening additional influence from lower latitudes becomes apparent in the model results. In the lower stratosphere export of vortex air leads only to a fraction of about 5% polar air in mid latitudes by the end of March. An upper limit for the contribution of ozone depleted vortex air on mid-latitude ozone loss is derived, indicating that the maximum final impact of dilution is on the order of 50%

    Palliative care for patients with end‐stage liver disease: An overview

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112227/1/cld478.pd
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