14,824 research outputs found
A Svarc-Milnor lemma for monoids acting by isometric embeddings
We continue our programme of extending key techniques from geometric group
theory to semigroup theory, by studying monoids acting by isometric embeddings
on spaces equipped with asymmetric, partially-defined distance functions. The
canonical example of such an action is a cancellative monoid acting by
translation on its Cayley graph. Our main result is an extension of the
Svarc-Milnor Lemma to this setting.Comment: 11 page
High resolution radio study of the Pulsar Wind Nebula within the Supernova Remnant G0.9+0.1
We have conducted a radio study at 3.6, 6 and 20 cm using ATCA and VLA and
reprocessed XMM-Newton and Chandra data of the pulsar wind nebula (PWN) in the
supernova remnant (SNR) G0.9+0.1. The new observations revealed that the
morphology and symmetry suggested by Chandra observations (torus and jet-like
features) are basically preserved in the radio range in spite of the rich
structure observed in the radio emission of this PWN, including several arcs,
bright knots, extensions and filaments. The reprocessed X-ray images show for
the first time that the X-ray plasma fills almost the same volume as the radio
PWN. Notably the X-ray maximum does not coincide with the radio maximum and the
neutron star candidate CXOU J174722.8-280915 lies within a small depression in
the radio emission. From the new radio data we have refined the flux density
estimates, obtaining S(PWN) ~ 1.57 Jy, almost constant between 3.6 and 20 cm.
For the whole SNR (compact core and shell), a flux density S(at 20 cm)= 11.5 Jy
was estimated. Based on the new and the existing 90 cm flux density estimates,
we derived alpha(PWN)=-0.18+/-0.04 and alpha(shell)=-0.68+/- 0.07. From the
combination of the radio data with X-ray data, a spectral break is found near
nu ~ 2.4 x 10^(12) Hz. The total radio PWN luminosity is L(radio)=1.2 x 10^(35)
erg s^(-1) when a distance of 8.5 kpc is adopted. By assuming equipartition
between particle and magnetic energies, we estimate a nebular magnetic field B
= 56 muG. The associated particle energy turns out to be U(part)=5 x 10^(47)
erg and the magnetic energy U(mag)=2 x 10^(47) erg. Based on an empirical
relation between X-ray luminosity and pulsar energy loss rate, and the
comparison with the calculated total energy, a lower limit of 1100 yr is
derived for the age of this PWN.Comment: 10 pages,8 figures, accepted for publication in A&A, June 13 200
Sedation for Gastrointestinal Endoscopic Procedures in the Elderly: Getting Safer but Still Not Nearly Safe Enough
Previously published UK reports showed that excessively large doses of benzodiazepines and opiates were being commonly used to sedate elderly patients for gastrointestinal (GI) endoscopy. This unsafe practice has lead to avoidable morbidity and mortality. We have taken the opportunity provided by recent reports to examine whether GI endoscopy sedation practice in the elderly has improved in the light of this evidence and the publication of guidelines in which specific recommendations on sedation dosage are given
Rotational friction on small globular proteins: Combined dielectric and hydrodynamic effect
Rotational friction on proteins and macromolecules is known to derive
contributions from at least two distinct sources -- hydrodynamic (due to
viscosity) and dielectric friction (due to polar interactions). In the existing
theoretical approaches, the effect of the latter is taken into account in an
{\it ad hoc} manner, by increasing the size of the protein with the addition of
a hydration layer. Here we calculate the rotational dielectric friction on a
protein () by using a generalized arbitrary charge distribution
model (where the charges are obtained from quantum chemical calculation) and
the hydrodynamic friction with stick boundary condition,
() by using the sophisticated theoretical technique known
as tri-axial ellipsoidal method, formulated by Harding [S. E. Harding, Comp.
Biol. Med. {\bf 12}, 75 (1982)]. The calculation of hydrodynamic friction is
done with only the dry volume of the protein (no hydration layer). We find that
the total friction obtained by summing up and
gives reasonable agreement with the experimental results,
i.e.,
Recommended from our members
The ErbB2ΔEx16 splice variant is a major oncogenic driver in breast cancer that promotes a pro-metastatic tumor microenvironment.
Amplification and overexpression of erbB2/neu proto-oncogene is observed in 20-30% human breast cancer and is inversely correlated with the survival of the patient. Despite this, somatic activating mutations within erbB2 in human breast cancers are rare. However, we have previously reported that a splice isoform of erbB2, containing an in-frame deletion of exon 16 (herein referred to as ErbB2ΔEx16), results in oncogenic activation of erbB2 because of constitutive dimerization of the ErbB2 receptor. Here, we demonstrate that the ErbB2ΔEx16 is a major oncogenic driver in breast cancer that constitutively signals from the cell surface. We further show that inducible expression of the ErbB2ΔEx16 variant in mammary gland of transgenic mice results in the rapid development of metastatic multifocal mammary tumors. Genetic and biochemical characterization of the ErbB2ΔEx16-derived mammary tumors exhibit several unique features that distinguish this model from the conventional ErbB2 ones expressing the erbB2 proto-oncogene in mammary epithelium. Unlike the wild-type ErbB2-derived tumors that express luminal keratins, ErbB2ΔEx16-derived tumors exhibit high degree of intratumoral heterogeneity co-expressing both basal and luminal keratins. Consistent with these distinct pathological features, the ErbB2ΔEx16 tumors exhibit distinct signaling and gene expression profiles that correlate with activation of number of key transcription factors implicated in breast cancer metastasis and cancer stem cell renewal
Morphology of the canine omentum, part 1: arterial landmarks that define the omentum
Although the omentum remains an enigmatic organ, research during the last decades has revealed its fascinating functions including fat storage, fluid drainage, immune activity, angiogenesis and adhesion. While clinicians both in human and veterinary medicine are continuously exploring new potential omental applications, detailed anatomical data on the canine omentum are currently lacking, and information is often retrieved from human medicine. In this study, the topographic anatomy of the canine greater and lesser omentum is explored in depth. Current nomenclature is challenged, and a more detailed terminology is proposed. Consistent arteries that are contained within folds of the superficial omental wall are documented, described and named, as they can provide the anatomical landmarks that are necessary for unambiguous scientific communication on the canine omentum. In an included dissection video, the conclusions and in situ findings described in this study are demonstrated
Legal determinants of external finance revisited : the inverse relationship between investor protection and societal well-being
This paper investigates relationships between corporate governance traditions and quality of life as measured by a number of widely reported indicators. It provides an empirical analysis of indicators of societal health in developed economies using a classification based on legal traditions. Arguably the most widely cited work in the corporate governance literature has been the collection of papers by La Porta et al. which has shown, inter alia, statistically significant relationships between legal traditions and various proxies for investor protection. We show statistically significant relationships between legal traditions and various proxies for societal health. Our comparative evidence suggests that the interests of investors may not be congruent with the interests of wider society, and that the criteria for judging the effectiveness of approaches to corporate governance should not be restricted to financial metrics
Faculty Recital: Max Schoenfeld, Flute; Harold Gray, Piano; La Vergne Monette, Soprano; Benny Kemp, Piano; July 28, 1975
Hayden AuditoriumMonday EveningJuly 28, 19758:15 p.m
American Anthem: Modern American History
This Teacher\u27s Edition of American Anthem: Modern American History covers the United States Before 1898 and with emphasis on the nation becoming a world power, the First World War, from war to peace, the roaring twenties, the Great Depression, the New Deal, World War II, the Cold War, post-war America, the Civil Rights Movement, the Vietnam War, a conservative era, and into the twenty-first century.https://scholarship.richmond.edu/bookshelf/1282/thumbnail.jp
- …