1,572 research outputs found
Coronal global EIT waves as tools for multiple diagnostics
Observations in EUV lines of the solar corona revealed large scale propagating waves generated by eruptive events able to travel across the solar disk for large distances. In the low corona, CMEs are known to generate, e.g. EIT waves which can be used to sample the coronal local and global magnetic field. This contribution presents theoretical models for finding values of magnetic field in the quiet Sun and coronal loops based on the interaction of global waves and local coronal loops as well as results on the generation and propagation of EIT waves. The physical connection between local and global solar coronal events (e.g. flares, EIT waves and coronal loop oscillations) will also be explored
Hilbert C*-modules and amenable actions
We study actions of discrete groups on Hilbert -modules induced from
topological actions on compact Hausdorff spaces. We show non-amenability of
actions of non-amenable and non-a-T-menable groups, provided there exists a
quasi-invariant probability measure which is sufficiently close to being
invariant.Comment: Final version, to appear in Studia Mathematic
Invariant expectations and vanishing of bounded cohomology for exact groups
We study exactness of groups and establish a characterization of exact groups
in terms of the existence of a continuous linear operator, called an invariant
expectation, whose properties make it a weak counterpart of an invariant mean
on a group. We apply this operator to show that exactness of a finitely
generated group implies the vanishing of the bounded cohomology of with
coefficients in a new class of modules, which are defined using the Hopf
algebra structure of .Comment: Final version, to appear in the Journal of Topology and Analysi
Cryogenic Thermal Distortion Performance Characterization for the JWST ISIM Structure
The James Webb Space Telescope (JWST) Integrated Science Instrument Module (ISIM) Structure is a precision optical metering structure for the JWST science instruments. Optomechanical performance requirements place stringent limits on the allowable thermal distortion of the metering structure between ambient and cryogenic operating temperature (~35 K). This paper focuses on thermal distortion testing and successful verification of performance requirements for the flight ISIM Structure. The ISIM Structure Cryoset Test was completed in Spring 2010 at NASA Goddard Space Flight Center in the Space Environment Simulator Chamber. During the test, the ISIM Structure was thermal cycled twice between ambient and cryogenic (~35 K) temperatures. Photogrammetry was used to measure the Structure in the ambient and cryogenic states for each cycle to assess both cooldown thermal distortion and repeatability. This paper will provide details on the post-processing of the metrology datasets completed to compare measurements with performance requirements
Emergence of structural and dynamical properties of ecological mutualistic networks
Mutualistic networks are formed when the interactions between two classes of
species are mutually beneficial. They are important examples of cooperation
shaped by evolution. Mutualism between animals and plants plays a key role in
the organization of ecological communities. Such networks in ecology have
generically evolved a nested architecture independent of species composition
and latitude - specialists interact with proper subsets of the nodes with whom
generalists interact. Despite sustained efforts to explain observed network
structure on the basis of community-level stability or persistence, such
correlative studies have reached minimal consensus. Here we demonstrate that
nested interaction networks could emerge as a consequence of an optimization
principle aimed at maximizing the species abundance in mutualistic communities.
Using analytical and numerical approaches, we show that because of the
mutualistic interactions, an increase in abundance of a given species results
in a corresponding increase in the total number of individuals in the
community, as also the nestedness of the interaction matrix. Indeed, the
species abundances and the nestedness of the interaction matrix are correlated
by an amount that depends on the strength of the mutualistic interactions.
Nestedness and the observed spontaneous emergence of generalist and specialist
species occur for several dynamical implementations of the variational
principle under stationary conditions. Optimized networks, while remaining
stable, tend to be less resilient than their counterparts with randomly
assigned interactions. In particular, we analytically show that the abundance
of the rarest species is directly linked to the resilience of the community.
Our work provides a unifying framework for studying the emergent structural and
dynamical properties of ecological mutualistic networks.Comment: 10 pages, 4 figure
Multicritical microscopic spectral correlators of hermitian and complex matrices
We find the microscopic spectral densities and the spectral correlators associated with multicritical
behavior for both hermitian and complex matrix ensembles, and show their universality.
We conjecture that microscopic spectral densities of Dirac operators in certain theories without
spontaneous chiral symmetry breaking may belong to these new universality classes
De novo loss of function mutations in KIAA2022 are associated with epilepsy and neurodevelopmental delay in females
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136530/1/cge12854_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136530/2/cge12854.pd
Trying Cases in the Media: Legal Ethics, Fair Trials and Free Press
The 2000 symposium consisted of a panel discussion which used role-playing and a mock trial to highlight the issues of lawyer/litigant comments to the press before and during trial and the dilemma of journalists confronted by court demands for documents, testimony, or sources of information obtained in the course of gathering news on pending trials. Participants included:
As United States Attorney for the Eastern District of Freedonia: John Douglas, Associate Professor of Law at the University of Richmond.
As Freedonia criminal defense lawyer: Gerald Zerkin, Private Defense Attorney.
As investigative journalist: Steve Nash, Associate Professor of Journalism at the University of Richmond.
As federal judge: Judge Margaret P. Spencer, Virginia Circuit Court Judge.
As media attorney: Craig Thomas Merritt, Attorney.
As first amendment attorney: J. Joshua Wheeler, Attorney and Director of Programs for the Thomas Jefferson Center for the Protection of Free Expression, and adjunct professor at University of Virginia.
As Chief Justice: Paul D. Carrington, The Chadwick Professor of Law at Duke University.
As Associate Justices of the United States Supreme Court: C. Thomas Dienes, Patricia Roberts Harris Professor of Law at George Washington University\u27s Law School; John E. Nowak, David C. Baum Professor of Law at the University of Illinois; Molly Delea, third-year law student, University of Richmond School of Law; Kate Murray, third-year law student, University of Richmond School of Law; Thomas Queen, third-year law student, University of Richmond School of Law; and Courtney Sydnor, third-year law student, University of Richmond School of Law
ChAInGeS: The Chandra Arp Interacting Galaxies Survey
We have conducted a statistical analysis of the ultra-luminous X-ray point
sources (ULXs; L(X) >= 10^39 erg/s) in a sample of galaxies selected from the
Arp Atlas of Peculiar Galaxies. We find a possible enhancement of a factor of
~2-4 in the number of ULXs per blue luminosity for the strongly interacting
subset. Such an enhancement would be expected if ULX production is related to
star formation, as interacting galaxies tend to have enhanced star formation
rates on average. For most of the Arp galaxies in our sample, the total number
of ULXs compared to the far-infrared luminosity is consistent with values found
earlier for spiral galaxies. This suggests that for these galaxies, ULXs trace
recent star formation. However, for the most infrared-luminous galaxies, we
find a deficiency of ULXs compared to the infrared luminosity. For these very
infrared-luminous galaxies, AGNs may contribute to powering the far-infrared;
alternatively, ULXs may be highly obscured in the X-ray in these galaxies and
therefore not detected by these Chandra observations. We determined local
UV/optical colors within the galaxies in the vicinity of the candidate ULXs
using GALEX UV and SDSS optical images. In most cases, the distributions of
colors are similar to the global colors of interacting galaxies. However, the u
- g and r - i colors at the ULX locations tend to be bluer on average than
these global colors, suggesting that ULXs are preferentially found in regions
with young stellar populations. In the Arp sample there is a possible
enhancement of a factor of ~2 - 5 in the fraction of galactic nuclei that are
X-ray bright compared to more normal spirals.Comment: 28 pages, 7 figures, Astronomical Journal, in pres
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