374 research outputs found
Studies of Tiros and Nimbus radiometric observations Final report
Data analyses of Tiros and Nimbus radiometric observation
Hidden spin-current conservation in 2d Fermi liquids
We report the existence of regimes of the two dimensional Fermi liquid that
show unusual conservation of the spin current and may be tuned by varying some
parameter like the density of fermions. We show that for reasonable models of
the effective interaction the spin current may be conserved in general in 2d,
not only for a particular regime. Low temperature spin waves propagate
distinctively in these regimes and entirely new ``spin-acoustic'' modes are
predicted for scattering-dominated temperature ranges. These new
high-temperature propagating spin waves provide a clear signature for the
experimental search of such regimes.Comment: 4 pages, no figures, revised version, accepted for pub. in the PR
Surface Region of Superfluid Helium as an Inhomogeneous Bose-Condensed Gas
We present arguments that the low density surface region of self-bounded
superfluid He systems is an inhomogeneous dilute Bose gas, with almost all
of the atoms occupying the same single-particle state at . Numerical
evidence for this complete Bose-Einstein condensation was first given by the
many-body variational calculations of He droplets by Lewart, Pandharipande
and Pieper in 1988. We show that the low density surface region can be treated
rigorously using a generalized Gross-Pitaevskii equation for the Bose order
parameter.Comment: 4 pages, 1 Postscript figur
Historical trends in iodine and selenium in soil and herbage at the Park Grass experiment, Rothamsted Research, UK
Long term trends in iodine and selenium retention in soil, and uptake by herbage, were investigated in archived samples from the Park Grass Experiment, initiated in 1856 at Rothamsted, UK. Soil (0-23 cm) and herbage samples from plots receiving various mineral fertilisers and organic manures, with and without lime, were analysed for Se and iodine (I) to assess the effect of soil amendment, annual rainfall, crop yield and changes in soil chemistry from 1876 to 2008. Comparing soil from limed and un-limed control (unfertilized) plots, TMAH-extractable Se and I concentrations both diverged, with time, with greater retention in un-limed plots; differences in concentration amounted to 92 and 1660 µg kg-1 for Se and I respectively after 105 yr. These differences were broadly consistent with estimated additions from rainfall and dry deposition. Offtake of both elements in herbage was negligible compared to soil concentrations and annual inputs (<0.003% of total soil I and <0.006% of total soil Se). A positive correlation was observed between I and Se concentrations in herbage, suggesting some common factors controlling bioavailability. A growth-dilution effect for I and Se was suggested by the positive correlation between growing season rainfall (GSR) and herbage yield together with soil-to-plant transfer factors decreasing with yield. Phosphate and sulphate fertilizers reduced I and Se herbage concentrations, both through ion competition and increased herbage yield. Results suggest that in intensive agriculture with soil pH control, the I requirement of grazing animals is not likely to be met by herbage alone
The Continuous Sample of Working Lives: improving its representativeness
This paper studies the representativeness of the Continuous Sample of Working Lives (CSWL), a set of anonymized microdata containing information on individuals from Spanish Social Security records. We examine several CSWL waves (2005-2013) and show that it is not representative for the population with a pension income. We then develop a methodology to draw a large dataset from the CSWL that is much more representative of the retired population in terms of pension type, gender and age. This procedure also makes it possible for users to choose between goodness of fit and subsample size. In order to illustrate the practical significance of our methodology, the paper also contains an application in which we generate a large subsample distribution from the 2010 CSWL. The results are striking: with a very small reduction in the size of the original CSWL, we significantly reduce errors in estimating pension expenditure for 2010, with a p value greater or equal to 0.999
Interaction-Dependent PCR: Identification of Ligand−Target Pairs from Libraries of Ligands and Libraries of Targets in a Single Solution-Phase Experiment
Interaction-dependent PCR (IDPCR) is a solution-phase method to identify binding partners from combined libraries of small-molecule ligands and targets in a single experiment. Binding between DNA-linked targets and DNA-linked ligands induces formation of an extendable duplex. Extension links codes that identify the ligand and target into one selectively amplifiable DNA molecule. In a model selection, IDPCR resulted in the enrichment of DNA encoding all five known protein−ligand pairs out of 67 599 possible sequences.Chemistry and Chemical Biolog
Nearly Perfect Fluidity: From Cold Atomic Gases to Hot Quark Gluon Plasmas
Shear viscosity is a measure of the amount of dissipation in a simple fluid.
In kinetic theory shear viscosity is related to the rate of momentum transport
by quasi-particles, and the uncertainty relation suggests that the ratio of
shear viscosity eta to entropy density s in units of hbar/k_B is bounded by a
constant. Here, hbar is Planck's constant and k_B is Boltzmann's constant. A
specific bound has been proposed on the basis of string theory where, for a
large class of theories, one can show that eta/s is greater or equal to hbar/(4
pi k_B). We will refer to a fluid that saturates the string theory bound as a
perfect fluid. In this review we summarize theoretical and experimental
information on the properties of the three main classes of quantum fluids that
are known to have values of eta/s that are smaller than hbar/k_B. These fluids
are strongly coupled Bose fluids, in particular liquid helium, strongly
correlated ultracold Fermi gases, and the quark gluon plasma. We discuss the
main theoretical approaches to transport properties of these fluids: kinetic
theory, numerical simulations based on linear response theory, and holographic
dualities. We also summarize the experimental situation, in particular with
regard to the observation of hydrodynamic behavior in ultracold Fermi gases and
the quark gluon plasma.Comment: 76 pages, 11 figures, review article, extensive revision
On the (Non) Existence of a Price Equilibrium in Delegation Games with Relative Performance Compensation
Age-Related Changes of Myelin Basic Protein in Mouse and Human Auditory Nerve
Age-related hearing loss (presbyacusis) is the most common type of hearing impairment. One of the most consistent pathological changes seen in presbyacusis is the loss of spiral ganglion neurons (SGNs). Defining the cellular and molecular basis of SGN degeneration in the human inner ear is critical to gaining a better understanding of the pathophysiology of presbyacusis. However, information on age-related cellular and molecular alterations in the human spiral ganglion remains scant, owing to the very limited availably of human specimens suitable for high resolution morphological and molecular analysis. This study aimed at defining age-related alterations in the auditory nerve in human temporal bones and determining if immunostaining for myelin basic protein (MBP) can be used as an alternative approach to electron microscopy for evaluating myelin degeneration. For comparative purposes, we evaluated ultrastructural alternations and changes in MBP immunostaining in aging CBA/CaJ mice. We then examined 13 temporal bones from 10 human donors, including 4 adults aged 38–46 years (middle-aged group) and 6 adults aged 63–91 years (older group). Similar to the mouse, intense immunostaining of MBP was present throughout the auditory nerve of the middle-aged human donors. Significant declines in MBP immunoreactivity and losses of MBP+ auditory nerve fibers were observed in the spiral ganglia of both the older human and aged mouse ears. This study demonstrates that immunostaining for MBP in combination with confocal microscopy provides a sensitive, reliable, and efficient method for assessing alterations of myelin sheaths in the auditory nerve. The results also suggest that myelin degeneration may play a critical role in the SGN loss and the subsequent decline of the auditory nerve function in presbyacusis
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