7,449 research outputs found
Effect of Our Galaxy's Motion on Weak Lensing Measurements of Shear and Convergence
In this work we investigate the effect on weak-lensing shear and convergence
measurements due to distortions from the Lorentz boost induced by our Galaxy's
motion. While no ellipticity is induced in an image from the Lorentz boost to
first order in beta = v/c, the image is magnified. This affects the inferred
convergence at a 10 per cent level, and is most notable for low multipoles in
the convergence power spectrum C {\kappa}{\kappa} and for surveys with large
sky coverage like LSST and DES. Experiments which image only small fractions of
the sky and convergence power spectrum determinations at l > 5 can safely
neglect the boost effect to first order in beta.Comment: 4 pages, replaced to reflect changes made for publication to MNRA
On the combination of omics data for prediction of binary outcomes
Enrichment of predictive models with new biomolecular markers is an important
task in high-dimensional omic applications. Increasingly, clinical studies
include several sets of such omics markers available for each patient,
measuring different levels of biological variation. As a result, one of the
main challenges in predictive research is the integration of different sources
of omic biomarkers for the prediction of health traits. We review several
approaches for the combination of omic markers in the context of binary outcome
prediction, all based on double cross-validation and regularized regression
models. We evaluate their performance in terms of calibration and
discrimination and we compare their performance with respect to single-omic
source predictions. We illustrate the methods through the analysis of two real
datasets. On the one hand, we consider the combination of two fractions of
proteomic mass spectrometry for the calibration of a diagnostic rule for the
detection of early-stage breast cancer. On the other hand, we consider
transcriptomics and metabolomics as predictors of obesity using data from the
Dietary, Lifestyle, and Genetic determinants of Obesity and Metabolic syndrome
(DILGOM) study, a population-based cohort, from Finland
On the ground states of the Bernasconi model
The ground states of the Bernasconi model are binary +1/-1 sequences of
length N with low autocorrelations. We introduce the notion of perfect
sequences, binary sequences with one-valued off-peak correlations of minimum
amount. If they exist, they are ground states. Using results from the
mathematical theory of cyclic difference sets, we specify all values of N for
which perfect sequences do exist and how to construct them. For other values of
N, we investigate almost perfect sequences, i.e. sequences with two-valued
off-peak correlations of minimum amount. Numerical and analytical results
support the conjecture that almost perfect sequences do exist for all values of
N, but that they are not always ground states. We present a construction for
low-energy configurations that works if N is the product of two odd primes.Comment: 12 pages, LaTeX2e; extended content, added references; submitted to
J.Phys.
The existence of an inverse limit of inverse system of measure spaces - a purely measurable case
The existence of an inverse limit of an inverse system of (probability) measure spaces has been investigated since the very beginning of the birth of the modern probability theory. Results from Kolmogorov
[10], Bochner [2], Choksi [5], Metivier [14], Bourbaki [3] among others have paved the way of the deep understanding of the problem under consideration. All the above results, however, call for some topological concepts, or at least ones which are closely related topological ones. In this paper we investigate purely measurable inverse systems of (probability) measure spaces, and give a sucient condition for the existence of a unique inverse limit. An example for the considered purely measurable inverse systems of (probability) measure spaces is also given
Vortices in the presence of a nonmagnetic atom impurity in 2D XY ferromagnets
Using a model of nonmagnetic impurity potential, we have examined the
behavior of planar vortex solutions in the classical two-dimensional XY
ferromagnets in the presence of a spin vacancy localized out of the vortex
core. Our results show that a spinless atom impurity gives rise to an effective
potential that repels the vortex structure.Comment: 6 pages, 2 figures, RevTex
Vortex polarity switching by a spin--polarized current
The spin-transfer effect is investigated for the vortex state of a magnetic
nanodot. A spin current is shown to act similarly to an effective magnetic
field perpendicular to the nanodot. Then a vortex with magnetization (polarity)
parallel to the current polarization is energetically favorable. Following a
simple energy analysis and using direct spin--lattice simulations, we predict
the polarity switching of a vortex. For magnetic storage devices, an electric
current is more effective to switch the polarity of a vortex in a nanodot than
the magnetic field
Noise-induced switching between vortex states with different polarization in classical two-dimensional easy-plane magnets
In the 2-dimensional anisotropic Heisenberg model with XY-symmetry there are
non-planar vortices which exhibit a localized structure of the z-components of
the spins around the vortex center. We study how thermal noise induces a
transition of this structure from one polarization to the opposite one. We
describe the vortex core by a discrete Hamiltonian and consider a stationary
solution of the Fokker-Planck equation. We find a bimodal distribution function
and calculate the transition rate using Langer's instanton theory (1969). The
result is compared with Langevin dynamics simulations for the full many-spin
model.Comment: 15 pages, 4 figures, Phys. Rev. B., in pres
Alfalfa: Crop for the Future
Alfalfa use by dairy cattle has decreased in recent years because of excessive nonprotein nitrogen and low fiber digestibility. Ideal attributes for plant modification of alfalfa may include those that increase milk potential per acre and/or per ton, enhance digestible NDF, improve protein content and amino acid balance, improve agronomic traits for insect protection (safer forage supply), herbicide tolerance, virus resistance, drought tolerance, cold tolerance, improved mineral availability and enhanced yield. Progress in attaining these attributes will accelerate with the use of biotechnology. Livestock and hay enterprises will benefit from alfalfa that is less prone to contain mycotoxins or toxic weeds, or to induce bloat; have improved nutrient utilization for milk and meat production; and produce less animal wastes resulting in improved efficiency, profitability, and a better environment. Value-added traits of alfalfa are needed to provide farmers new high value profitable products. Processing alfalfa to obtain value added products includes three different fractionation methods: 1) wet fractionation; separation into juice fraction and a fiber fraction, 2) dry fractionation; separation into leaves and stems, and 3) fractionation by passage of the whole herbage through the digestive systems of ruminant animals, leaving a high fiber residue. Phytase from transgenic alfalfa has been tested in poultry and swine rations. Alfalfa hay can be fractionated to yield stems and leaf meal. Alfalfa leaf meal has been shown to be acceptable supplement to replace a portion of alfalfa hay and soybean meal in diets of lactating dairy cattle, replace protein supplement in beef cow diets, finishing steer diets and diets of growing turkeys. The fiber portion of alfalfa can produce lactic acid, ethanol or a bioadhesives for use in plywood
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