9,266 research outputs found
Evidenceābased guidelines support integrated disease management as the optimal model of haemophilia care
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/1/hae12997_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/2/hae12997.pd
Evidenceābased guidelines support integrated disease management as the optimal model of haemophilia care
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/1/hae12997_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/2/hae12997.pd
Microscopic Selection of Fluid Fingering Pattern
We study the issue of the selection of viscous fingering patterns in the
limit of small surface tension. Through detailed simulations of anisotropic
fingering, we demonstrate conclusively that no selection independent of the
small-scale cutoff (macroscopic selection) occurs in this system. Rather, the
small-scale cutoff completely controls the pattern, even on short time scales,
in accord with the theory of microscopic solvability. We demonstrate that
ordered patterns are dynamically selected only for not too small surface
tensions. For extremely small surface tensions, the system exhibits chaotic
behavior and no regular pattern is realized.Comment: 6 pages, 5 figure
Mott scattering of polarized electrons in a strong laser field
We present analytical and numerical results of the relativistic calculation
of the transition matrix element and differential cross section for
Mott scattering of initially polarized Dirac particles (electrons) in the
presence of strong laser field with linear polarization. We use exact
Dirac-Volkov wave functions to describe the dressed electrons and the collision
process is treated in the first Born approximation. The influence of the laser
field on the degree of polarization of the scattered electron is reported.Comment: 12 pages, 11 figures, Revte
Stable hydrogen isotope ratios in crystal water of clay minerals
Hydrogen is the most abundant element in the Universe. But the utilization of the H isotopic composition (Ī“H-2 value) of soil to elucidate biogeochemical processes or to serve as a palaeo climate proxy is still in its infancy. In our research, we will focus on the Ī“H-2 value of nonexchangeable H in the clay fraction of soils. The Ī“H-2 value of structural H in clay minerals ā mainly from C-poor subsoils - has been studied since the 1970s. The Ī“H-2 value of clay minerals mainly depends on (a) the average Ī“H-2 value of ambient water at the site and time of formation, and on (b) the size of the equilibrium isotopic fractionation factor between water and clay mineral at the temperature of formation. In our research, we will focus on the Ī“H-2 value of nonexchangeable H in the clay fraction of soils. Only nonexchangeable H in in structural water of minerals preserves its inherited Ī“H-2 value and does not exchange with water at temperatures usually occurring in soil environments at the Earthās surface. Nonexchangeable H is bound in crystal water, which integrates the Ī“H-2 value of soil water over several millennia. This is in turn determined by palaeoclimatic variations of the precipitationās Ī“H-2 signal with distinguishable shifts e.g., from Pleistocene to Holocene. For a global data set, Ruppenthal (2014) reported a close correlation of bulk soil Ī“H-2 values with those of the mean local precipitation and confirmed this for organic matter, while the clay fraction of soils was up to now not studied. We will adapt a steam equilibration method with water vapor of known H isotopic composition ā formerly applied by Ruppenthal (2014) on SOM and bulk soil ā to clay fractions and compare our results to the hitherto used heating treatments (200-250Ā°C) under vacuum. We expect that the Ī“H-2 signal of the clay fraction of Bt horizons will serve to differentiate soils developed in different climatic epochs (e.g., Holocene, last interstadial, last interglacial) by analyzing dated palaeo soil samples. To test the hypothesis that there is a similar global regression line of the Ī“H-2 values in structural water of clay as up to now reported for bulk soils and soil organic matter, we will analyze the clay fraction in a global set of soil samples
Stable hydrogen isotope ratios in soil organic matter
Stable H isotope ratios are a promising indicator of OM transformation processes (Schimmelmann et al., 2006). Ī“2H values of bulk organic matter and of specific organic compounds can be used as ecological tracer and forensic tool if the proportion of H that readily exchanges with ambient moisture is accounted for (Wassenaar & Hobson, 1998). There are a few reports about the H isotope ratios in plant-soil systems illustrating that there is little knowledge of the controls of the isotopic composition of the non-exchangeable H fraction of bulk OM (Schimmelmann et al., 2006; Ruppenthal et al., 2015). The increasingly closer relationship between Ī“2H values of rainfall and of non-exchangeable H in OM (Ī“2Hn) in the order, plant ā plant litter (above- and belowground) ā soil along a climatic gradient (Ruppenthal et al., 2015) suggests that decomposition influences Ī“2Hn values in OM in a systematic way. However, there are knowledge gaps concerning the fractionation factors and the extent of incorporation of ambient water-H into the nonexchangeable fraction of H in OM during decomposition. Our research will focus on the mechanisms responsible for the strong correlation between Ī“2H values in rainfall and Ī“2Hn values of SOM. Therefore, our study aims to investigate (1) the incorporation of ambient water-H into the nonexchangeable H fraction in OM during decomposition by heterotrophic bacteria as model organisms and quantify apparent fractionation factors, (2) the extent of incorporation of ambient water into the nonexchangeable H fraction of OM by the soil microbial community under laboratory conditions, and (3) the extent to which H is incorporated into nonexchangeable OM pool from ambient water during decomposition of aboveground litter under field conditions. We will work with microcosms using two bacteria species and determine decomposition rates of litter. Steam equilibration (Ruppenthal et al., 2015) and TC/EA-IRMS are used as analytical tools. We expect that different decomposition rates because of differences in litter quality will be reflected by the extent of H incorporation from ambient water into the nonexchangeable H fraction of the products. Additionally, different litter types enriched in 2H will be buried in soil of forest stands. We hypothesize that the incorporation of 2H-depleted ambient water into 2H-enriched nonexchangeable H fraction of OM will depend on litter type, soil moisture/ temperature, and the heterotrophic activity during the experiment
Two-finger selection theory in the Saffman-Taylor problem
We find that solvability theory selects a set of stationary solutions of the
Saffman-Taylor problem with coexistence of two \it unequal \rm fingers
advancing with the same velocity but with different relative widths
and and different tip positions. For vanishingly small
dimensionless surface tension , an infinite discrete set of values of the
total filling fraction and of the relative
individual finger width are selected out of a
two-parameter continuous degeneracy. They scale as
and . The selected values of differ from
those of the single finger case. Explicit approximate expressions for both
spectra are given.Comment: 4 pages, 3 figure
A Compendium of Far-Infrared Line and Continuum Emission for 227 Galaxies Observed by the Infrared Space Observatory
Far-infrared line and continuum fluxes are presented for a sample of 227
galaxies observed with the Long Wavelength Spectrometer on the Infrared Space
Observatory. The galaxy sample includes normal star-forming systems,
starbursts, and active galactic nuclei covering a wide range of colors and
morphologies. The dataset spans some 1300 line fluxes, 600 line upper limits,
and 800 continuum fluxes. Several fine structure emission lines are detected
that arise in either photodissociation or HII regions: [OIII]52um, [NIII]57um,
[OI]63um, [OIII]88um, [NII]122um, [OI]145um, and [CII]158um. Molecular lines
such as OH at 53um, 79um, 84um, 119um, and 163um, and H2O at 58um, 66um, 75um,
101um, and 108um are also detected in some galaxies. In addition to those lines
emitted by the target galaxies, serendipitous detections of Milky Way
[CII]158um and an unidentified line near 74um in NGC1068 are also reported.
Finally, continuum fluxes at 52um, 57um, 63um, 88um, 122um, 145um, 158um, and
170um are derived for a subset of galaxies in which the far-infrared emission
is contained within the ~75" ISO LWS beam. The statistics of this large
database of continuum and line fluxes, including trends in line ratios with the
far-infrared color and infrared-to-optical ratio, are explored.Comment: Accepted for publication in the Astrophysical Journal Supplement
Serie
Southwest Pacific Ocean Circulation and Climate Experiment (SPICE) - part I. Scientific background
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