Aspects of topology of condensates and knotted solitons in condensed matter systems

The knotted solitons introduced by Faddeev and Niemi is presently a subject of great interest in particle and mathematical physics. In this paper we give a condensed matter interpretation of the recent results of Faddeev and Niemi.Comment: v2: Added a reference to the paper E. Babaev, L.D. Faddeev and A.J. Niemi cond-mat/0106152 where an exact equivalence was shown between the two-condensate Ginzburg-Landau model and a version of Faddeev model. Miscelaneous links related to knotted solitons are available at the author homepage at http://www.teorfys.uu.se/PEOPLE/egor/ . Animations of knotted solitons by Hietarinta and Salo are available at http://users.utu.fi/h/hietarin/knots/c45_p2.mp

Admission Hyperglycemia in Setting of Acute Heart Failure is Associated with Increased In-hospital Mortality Among Patients without Diabetes

Background: Heart Failure (HF) in the setting of comorbid diabetes mellitus (DM) has been extensively examined and is associated with increased mortality. More recently, hyperglycemia independent of DM status during critical illness admissions has become recognized as an indicator of poor outcomes. Despite evolving understanding of DM in the setting of acute HF, hyperglycemia at time of admission for acute HF has not been examined with regard to in-hospital treatment and patient outcomes. Objective: The goal of this study is to examine differences in in-hospital treatment and outcomes of patients hospitalized for acute HF according to glycemic status. Methods: The sample consisted of 9,748 residents of the Worcester (MA) metropolitan area hospitalized at all 11 greater Worcester medical centers for acute decompensated HF during the years 1995 - 2004 with data available on diabetic status and admission glucose measurements. Patients were stratified into three groups based on history of DM and admission hyperglycemia defined by glucose ≥200 mg/dL: 1) nondiabetic, normoglycemic (NDNG); 2) non-diabetic, hyperglycemic (NDHG); and 3) diabetic (DM). Results: Non-diabetic, normoglycemic patients were similar to NDHG patients with respect to age and medical history and were significantly older and less likely to have a history of various comorbid conditions such as hypertension, stroke and renal disease when compared to diabetics (p-values Conclusions: The results of our population-based investigation suggest that non-diabetic patients hospitalized for acute HF who are hyperglycemic at the time of admission represent a vulnerable group of patients at risk for increased mortality during hospitalization. Hyperglycemia ≥200 mg/dL during acute HF hospitalization should be taken into account when providing in-hospital management for HF with additional consideration given to ascertainment of diabetic status and glycemic control

New Limits to the Infrared Background: Bounds on Radiative Neutrino Decay and on Contributions of Very Massive Objects to the Dark Matter Problem

From considering the effect of γ-γ interactions on recently observed TeV gamma-ray spectra, improved limits are set to the density of extragalactic infrared photons which are robust and essentially model independent. The resulting limits are more than an order of magnitude more restrictive than direct observations in the 0.025–0.3 eV regime. These limits are used to improve constraints on radiative neutrino decay in the mass range above 0.05 eV and to rule out very massive objects as providing the dark matter needed to explain galaxy rotation curves. Lower bounds on the maximum distance which TeV gamma rays may probe are also derived

Signatures of stirring and mixing near the Gulf Stream front

In October, 1986 the surface waters adjacent to the Gulf Stream front were surveyed with an undulating profiler to describe the finescale structure of the mixed layer. The profiler was a Seasoar equipped with a CTD and fluorometer. The survey first defined the structure of a cyclonic eddy which resembled frontal eddies of the South Atlantic Bight in sea surface temperature imagery. The Seasoar transects revealed, however, that the cyclonic eddy lacked a cold dome typically seen in frontal eddies. Farther downstream the Seasoar defined the structure of streamers of Gulf Stream and Shelf water wrapped about the southern edge of a warm-core ring. The streamers had lateral and along-axis dimensions on the order of ≈ 10 km and 100 km, respectively, and were bordered by narrow intrusive features. The temporal history of the streamers was described from SST imagery, and the surface flow derived from ship\u27s drift vectors. CTD casts taken while following an isopycnal float provided a means to examine the structure of the intrusive features. Interleaving was evident at the boundaries of the streamers and intrusive features where high conductivity Cox numbers were concentrated, suggesting elevated microstructure activity. The Turner angle distribution, indicating either saltfingering or diffusive convection, did not correlate well with the Cox number distribution. This is interpreted as evidence that lateral, rather than diapycnal, mixing was the process mediating the exchange of properties at the boundaries of contrasting water types. In contrast to physical properties, the distribution of fluorescence showed relatively less structure in the surface layer between the ring and Gulf Stream front. In the surface layers of the two streamers the pigment and bacterial biomass, and the diatom species composition, were typical of Slope water communities. We hypothesize that small-scale mixing processes concentrated at the boundaries of the streamers were the mechanism by which Slope water plankton were seeded into streamers of different hydrographic origins. Presumably, high netplankton growth rates allowed the Slope water species to dominate the communities in the streamers

Tunneling Anisotropic Magnetoresistance in Co/AlOx/Au Tunnel Junctions

We observe spin-valve-like effects in nano-scaled thermally evaporated Co/AlOx/Au tunnel junctions. The tunneling magnetoresistance is anisotropic and depends on the relative orientation of the magnetization direction of the Co electrode with respect to the current direction. We attribute this effect to a two-step magnetization reversal and an anisotropic density of states resulting from spin-orbit interaction. The results of this study points to future applications of novel spintronics devices involving only one ferromagnetic layer.Comment: 11 pages, 5 figures. Accpted for publishing on Nano Letters, 200

Population demography maintains biogeographic boundaries

Funding Information: This manuscript was the result of a working group funded by a Quebec Center for Biodiversity Science grant to JPL and KEM. We thank Ben Holt and the Center for Macroecology, Evolution and Climate for sharing their map of mammal biogeographic regions. We thank Laura Pollock, Isaac Eckert and Federico Riva for comments on the written document and discussion of the topic. We also thank Anna Hargreaves, Brian Leung, Jonathan Belmaker, Lilian Sales and Shahar Chaikin for additional discussions. We are also grateful to the authors whose work provided the raw data for this synthesis. KEM is supported by a NSERC Discovery Grant. GM and JPL were supported by the Concordia University Research Chair in Biodiversity and Ecosystem Functioning. GM is additionally supported by a Concordia Graduate Fellowship. CS and CJG were supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant to CJG. CS was also supported by a U. Manitoba Graduate Fellowship, and a U. Manitoba Graduate Enhancement of Tri‐council funding grant to CJG. The authors declare no conflict of interest.Peer reviewedPostprin

Near-Infrared Synchrotron Emission from Cas A

High energy observations of Cas A suggested the presence of synchrotron radiation, implying acceleration of cosmic rays by young supernova remnants. We detect synchrotron emission from Cas A in the near-infrared using Two Micron All Sky Survey (2MASS) and Palomar 200 inch PFIRCAM observations. The remnant is detected in J, H, and Ks bands, with Ks band brightest and J faint. In the J and H bands, bright [Fe II] lines (1.24um and 1.64um) are detected spectroscopically. The Palomar observations include Ks continuum, narrow-band 1.64um (centered on [Fe II]) and 2.12um (centered on H2(1-0)) images. While the narrow-band 1.64um image shows filamentary and knotty structures, similar to the optical image, the Ks image shows a relatively smooth, diffuse shell, remarkably similar to the radio image. The broad-band near-infrared fluxes of Cas A are generally consistent with, but a few tens of percent higher than, an extrapolation of the radio fluxes. The hardening to higher frequencies is possibly due to nonlinear shock acceleration and/or spectral index variation across the remnant. We show evidence of spectral index variation. The presence of near-infrared synchrotron radiation requires the roll-off frequency to be higher than 1.5e14 Hz, implying that electrons are accelerated to energies of at least 0.2 TeV. The morphological similarity in diffuse emission between the radio and Ks band images implies that synchrotron losses are not dominant. Our observations show unambiguous evidence that the near-infrared Ks band emission of Cas A is from synchrotron emission by accelerated cosmic-ray electrons.Comment: accepted by Ap