23,208 research outputs found
Inelastic X-ray scattering from valence electrons near absorption edges of FeTe and TiSe
We study resonant inelastic x-ray scattering (RIXS) peaks corresponding to
low energy particle-hole excited states of metallic FeTe and semi-metallic
TiSe for photon incident energy tuned near the absorption edge of
Fe and Ti respectively. We show that the cross section amplitudes are well
described within a renormalization group theory where the effect of the core
electrons is captured by effective dielectric functions expressed in terms of
the the atomic scattering parameters of Fe and Ti. This method can be
used to extract the dynamical structure factor from experimental RIXS spectra
in metallic systems.Comment: 6 pages, 4 figure
Devroye Inequality for a Class of Non-Uniformly Hyperbolic Dynamical Systems
In this paper, we prove an inequality, which we call "Devroye inequality",
for a large class of non-uniformly hyperbolic dynamical systems (M,f). This
class, introduced by L.-S. Young, includes families of piece-wise hyperbolic
maps (Lozi-like maps), scattering billiards (e.g., planar Lorentz gas),
unimodal and H{\'e}non-like maps. Devroye inequality provides an upper bound
for the variance of observables of the form K(x,f(x),...,f^{n-1}(x)), where K
is any separately Holder continuous function of n variables. In particular, we
can deal with observables which are not Birkhoff averages. We will show in
\cite{CCS} some applications of Devroye inequality to statistical properties of
this class of dynamical systems.Comment: Corrected version; To appear in Nonlinearit
New Indicators for AGN Power: The Correlation Between [O IV] lambda 25.89 micron and Hard X-ray Luminosity for Nearby Seyfert Galaxies
We have studied the relationship between the [O IV] lambda 25.89 micron
emission line luminosities, obtained from Spitzer spectra, the X-ray continua
in the 2-10 keV band, primarily from ASCA, and the 14-195 keV band obtained
with the SWIFT/Burst Alert Telescope (BAT), for a sample of nearby (z < 0.08)
Seyfert galaxies. For comparison, we have examined the relationship between the
[O III] 5007, the 2-10 keV and the 14-195 keV luminosities for the same set of
objects. We find that both the [O IV] and [O III] luminosities are
well-correlated with the BAT luminosities. On the other hand, the [O III]
luminosities are better-correlated with 2-10 keV luminosities than are those of
[O IV]. When comparing [O IV] and [O III] luminosities for the different types
of galaxies, we find that the Seyfert 2's have significantly lower [O III] to
[O IV] ratios than the Seyfert 1's. We suggest that this is due to more
reddening of the narrow line region (NLR) of the Seyfert 2's. Assuming Galactic
dust to gas ratios, the average amount of extra reddening corresponds to a
hydrogen column density of ~ few times 10^21 cm^-2, which is a small fraction
of the X-ray absorbing columns in the Seyfert 2's. The combined effects of
reddening and the X-ray absorption are the probable reason why the [O III]
versus 2-10 keV correlation is better than the [O IV] versus 2-10 keV, since
the [O IV] emission line is much less affected by extinction. Overall, we find
the [O IV] to be an accurate and truly isotropic indicator of the power of the
AGN. This suggests that it can be useful in deconvolving the contribution of
the AGN and starburst to the spectrum of Compton-thick and/or X-ray weak
sources.Comment: Accepted for publication in the Astrophysical Journal. 31 pages, 6
figures, 4 table
Pauli Paramagnetic Effects on Vortices in Superconducting TmNi2B2C
The magnetic field distribution around the vortices in TmNi2B2C in the
paramagnetic phase was studied experimentally as well as theoretically. The
vortex form factor, measured by small-angle neutron scattering, is found to be
field independent up to 0.6 Hc2 followed by a sharp decrease at higher fields.
The data are fitted well by solutions to the Eilenberger equations when
paramagnetic effects due to the exchange interaction with the localized 4f Tm
moments are included. The induced paramagnetic moments around the vortex cores
act to maintain the field contrast probed by the form factor.Comment: 4 pages, 4 figure
Recommended from our members
Defining Authentic Classroom Assessment
A commonly advocated best practice for classroom assessment is to make the assessments authentic. Authentic is often used as meaning the mirroring of real-world tasks or expectations. There is no consensus, however, in the actual definition of the term or the characteristics of an authentic classroom assessment. Sometimes, the realistic component is not even an element of a researcher\u27s or practitioner\u27s meaning. This study presents a conceptual analysis of authentic as it is used in educational research and training to describe an approach to classroom assessment. Nine distinct components or dimensions of authenticity are identified and only one of those is the realistic nature of the assessment. Accessed 54,632 times on https://pareonline.net from January 12, 2012 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right
Southeast Research and Demonstration Farm Field Day is June 23, 2015
Certified crop advisers (CCAs) can earn 4.5 hours of credit in soil and water management by attending a special CCA morning session, followed by the afternoon spring field day tour at the Southeast Iowa Research and Demonstration Farm near Crawfordsville on June 23, 2015
The static allometry of sexual and non-sexual traits in vervet monkeys
Sexual traits vary tremendously in static allometry. This variation may be explained in part by body size-related differences in the strength of selection. We tested this hypothesis in two populations of vervet monkeys, using estimates of the level of condition dependence for different morphological traits as a proxy for body size-related variation in the strength of selection. In support of the hypothesis, we found that the steepness of allometric slopes increased with the level of condition dependence. One trait of particular interest, the penis, had shallow allometric slopes and low levels of condition dependence, in agreement with one of the most consistent patterns yet detected in the study of allometry, namely that of genitalia exhibiting shallow allometries.This research was supported by NIH grant R01RR0163009
Pseudogap in the chain states of YBCO
As established by scanning tunneling microscopy (STM) cleaved surfaces of the
high temperature superconductor YBaCuO develop charge
density wave (CDW) modulations in the one-dimensional (1D) CuO chains. At the
same time, no signatures of the CDW have been reported in the spectral function
of the chain band previously studied by photoemission. We use soft X-ray angle
resolved photoemission (SX-ARPES) to detect a chain-derived surface band that
had not been detected in previous work. The for the new surface
band is found to be 0.55\,\AA, which matches the wave vector of the CDW
observed in direct space by STM. This reveals the relevance of the Fermi
surface nesting for the formation of CDWs in the CuO chains in
YBaCuO. In agreement with the short range nature of the
CDW order the newly detected surface band exhibits a pseudogap, whose energy
scale also corresponds to that observed by STM
Generic Multifractality in Exponentials of Long Memory Processes
We find that multifractal scaling is a robust property of a large class of
continuous stochastic processes, constructed as exponentials of long-memory
processes. The long memory is characterized by a power law kernel with tail
exponent , where . This generalizes previous studies
performed only with (with a truncation at an integral scale), by
showing that multifractality holds over a remarkably large range of
dimensionless scales for . The intermittency multifractal coefficient
can be tuned continuously as a function of the deviation from 1/2 and of
another parameter embodying information on the short-range amplitude
of the memory kernel, the ultra-violet cut-off (``viscous'') scale and the
variance of the white-noise innovations. In these processes, both a viscous
scale and an integral scale naturally appear, bracketing the ``inertial''
scaling regime. We exhibit a surprisingly good collapse of the multifractal
spectra on a universal scaling function, which enables us to derive
high-order multifractal exponents from the small-order values and also obtain a
given multifractal spectrum by different combinations of and
.Comment: 10 pages + 9 figure
- …