235,418 research outputs found
Painlev\'e V and time dependent Jacobi polynomials
In this paper we study the simplest deformation on a sequence of orthogonal
polynomials, namely, replacing the original (or reference) weight
defined on an interval by It is a well-known fact that under
such a deformation the recurrence coefficients denoted as and
evolve in according to the Toda equations, giving rise to the
time dependent orthogonal polynomials, using Sogo's terminology. The resulting
"time-dependent" Jacobi polynomials satisfy a linear second order ode. We will
show that the coefficients of this ode are intimately related to a particular
Painlev\'e V. In addition, we show that the coefficient of of the
monic orthogonal polynomials associated with the "time-dependent" Jacobi
weight, satisfies, up to a translation in the Jimbo-Miwa -form of
the same while a recurrence coefficient is up to a
translation in and a linear fractional transformation
These results are found
from combining a pair of non-linear difference equations and a pair of Toda
equations. This will in turn allow us to show that a certain Fredholm
determinant related to a class of Toeplitz plus Hankel operators has a
connection to a Painlev\'e equation
Prediction of the bias voltage dependent magnetic contrast in spin-polarized scanning tunneling microscopy
This work is concerned with the theoretical description of the contrast,
i.e., the apparent height difference between two lateral surface positions on
constant current spin-polarized scanning tunneling microscopy (SP-STM) images.
We propose a method to predict the bias voltage dependent magnetic contrast
from single point tunneling current or differential conductance measurements,
without the need of scanning large areas of the surface. Depending on the
number of single point measurements, the bias positions of magnetic contrast
reversals and of the maximally achievable magnetic contrast can be determined.
We validate this proposal by simulating SP-STM images on a complex magnetic
surface employing a recently developed approach based on atomic superposition.
Furthermore, we show evidence that the tip electronic structure and magnetic
orientation have a major effect on the magnetic contrast. Our theoretical
prediction is expected to inspire experimentalists to considerably reduce
measurement efforts for determining the bias dependent magnetic contrast on
magnetic surfaces.Comment: 28 pages manuscript, 1 table, 6 figure
Determination of Frequency and Distribution of Hessian Fly (Diptera: Cecidomyiidae) Biotypes in the Northeastern Soft Wheat Region
Fifteen collections of Hessian flies from the northern soft winter wheat region of the United States were used to determine the composition and frequency of biotypes. The wheat cultivars \u27Seneca\u27 (H7Hs), \u27Monon\u27 (H3), \u27Knox 62\u27 (~, H7Hg), and \u27Abe\u27 (Hs) were used as differentials. Biotypes J and L replaced biotype B as the prevalent biotype in Indiana, since wheat cultivars having the Hs and the H6 genes have been grown. Biotype GP, the least virulent of any Hessian fly biotypes, was still present in New York indicating that wheat cuItivars with no genes for resistance are still being grown there. The genetic variability of Hessian fly biotypes that enables them to overcome the resistance in wheat cultivars is discussed
The GTC exoplanet transit spectroscopy survey X. Stellar spots versus Rayleigh scattering: the case of HAT-P-11b
Rayleigh scattering in a hydrogen-dominated exoplanet atmosphere can be
detected from ground or space based telescopes, however, stellar activity in
the form of spots can mimic Rayleigh scattering in the observed transmission
spectrum. Quantifying this phenomena is key to our correct interpretation of
exoplanet atmospheric properties. We obtained long-slit optical spectroscopy of
two transits of HAT-P-11b with the Optical System for Imaging and
low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) at Gran Telescopio
Canarias (GTC) on August 30 2016 and September 25 2017. We integrated the
spectrum of HAT-P-11 and one reference star in several spectroscopic channels
across the 400-785 nm region, creating numerous light curves of
the transits. We fit analytic transit curves to the data taking into account
the systematic effects and red noise present in the time series in an effort to
measure the change of the planet-to-star radius ratio
() across wavelength. By fitting both transits
together, we find a slope in the transmission spectrum showing an increase of
the planetary radius towards blue wavelengths. A closer inspection to the
transmission spectrum of the individual data sets reveals that the first
transit presents this slope while the transmission spectrum of the second data
set is flat. Additionally we detect hints of Na absorption in the first night,
but not in the second. We conclude that the transmission spectrum slope and Na
absorption excess found in the first transit observation are caused by
unocculted stellar spots. Modeling the contribution of unocculted spots to
reproduce the results of the first night we find a spot filling factor of
and a spot-to-photosphere temperature difference
of K.Comment: Accepted for publication in Astronomy & Astrophysics, 13 page
Rate of Convergence Towards Semi-Relativistic Hartree Dynamics
We consider the semi-relativistic system of gravitating Bosons with
gravitation constant . The time evolution of the system is described by the
relativistic dispersion law, and we assume the mean-field scaling of the
interaction where and while fixed. In
the super-critical regime of large , we introduce the regularized
interaction where the cutoff vanishes as . We show that the
difference between the many-body semi-relativistic Schr\"{o}dinger dynamics and
the corresponding semi-relativistic Hartree dynamics is at most of order
for all , i.e., the result covers the sub-critical regime and
the super-critical regime. The dependence of the bound is optimal.Comment: 29 page
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