8,022 research outputs found
Second Law Violations in Lovelock Gravity for Black Hole Mergers
We study the classical second law of black hole thermodynamics, for Lovelock
theories (other than General Relativity), in arbitrary dimensions. Using the
standard formula for black hole entropy, we construct scenarios involving the
merger of two black holes in which the entropy instantaneously decreases. Our
construction involves a Kaluza-Klein compactification down to a dimension in
which one of the Lovelock terms is topological. We discuss some open issues in
the definition of the second law which might be used to compensate this entropy
decrease.Comment: 15 pages, 1 figure, v2 Title change & minor revisions to match
published version, v3 fixed accidental deletion of author name
A very high accuracy potential energy surface for H3
An exact quantum Monte Carlo (EQMC) method was used to calculate the potential energy surface (PES) for the ground electronic state of H3 over a grid of about 76000 nuclear geometries. The absolute abinitio statistical or sampling error of the calculation was ±0.01 kcal mol^-1 for energies (V) smaller than 3 eV. This PES was fitted by a three-dimensional cubic spline method and the fitting accuracy was determined from a set of 3684 randomly selected nuclear geometries not used in the fitting. For the range V3 eV the rms fitting error was ±0.010 kcal mol^-1, and the absolute value of the corresponding maximum error was 0.018 kcal mol^-1. This fitted EQMC PES is an order of magnitude more accurate than the best PES previously obtained for this system. Detailed comparisons are made with previous PESs, for the more dynamically important nuclear configurations
Open ocean carbon monoxide photo-production
Sunlight-initiated photolysis of chromophoric dissolved organic matter (CDOM) is the dominant source of carbon monoxide (CO) in the open-ocean. A modelling study was conducted to constrain this source. Spectral solar irradiance was obtained from two models (GCSOLAR and SMARTS2). Water-column CDOM and total light absorption were modelled using spectra collected along a Meridional transect of the Atlantic ocean using a 200-cm pathlength liquid waveguide UV-visible spectrophotometer. Apparent quantum yields for the production of CO (AQYCO) from CDOM were obtained from a parameterisation describing the relationship between CDOM light absorption coefficient and AQYCO and the CDOM spectra collected. The sensitivity of predicted rates to variations in model parameters (solar irradiance, cloud cover, surface-water reflectance, CDOM and whole water light absorbance, and AQYCO was assessed. The model\u27s best estimate of open-ocean CO photoproduction was 47 +/- 7 Tg CO-C yr-1, with lower and upper limits of 38 and 84 Tg CO-C yr-1, as indicated by sensitivity analysis considering variations in AQYs, CDOM absorbance, and spectral irradiance. These results represent significant constraint of open-ocean CO photoproduction at the lower limit of previous estimates. Based on these results, and their extrapolation to total photochemical organic carbon mineralisation, we recommend a downsizing of the role of photochemistry in the open-ocean carbon cycle.
(c) 2006 Elsevier Ltd. All rights reserved
Observation of collapse of pseudospin order in bilayer quantum Hall ferromagnets
The Hartree-Fock paradigm of bilayer quantum Hall states with finite
tunneling at filling factor =1 has full pseudospin ferromagnetic order
with all the electrons in the lowest symmetric Landau level. Inelastic light
scattering measurements of low energy spin excitations reveal major departures
from the paradigm at relatively large tunneling gaps. The results indicate the
emergence of a novel correlated quantum Hall state at =1 characterized by
reduced pseudospin order. Marked anomalies occur in spin excitations when
pseudospin polarization collapses by application of in-plane magnetic fields.Comment: ReVTeX4, 4 pages, 3 EPS figure
Posttransplant lymphoproliferative disorders in neuronal xenotransplanted macaques
Posttransplant lymphoproliferative disorders (PTLDs) are a heterogeneous group of lymphoid proliferations that occur in the setting of depressed T-cell function due to immunosuppressive therapy used following solid organ transplantation, hematopoietic stem cell transplantation, and also xenotransplantation. In the present study, 28 immunosuppressed parkinsonian Macaca fascicularis were intracerebrally injected with wild-type or CTLA4-Ig transgenic porcine xenografts to identify a suitable strategy to enable long-term cell survival, maturation, and differentiation. Nine of 28 (32%) immunosuppressed primates developed masses compatible with PTLD, located mainly in the gastrointestinal tract and/or nasal cavity. The masses were classified as monomorphic PTLD according to the World Health Organization classification. Immunohistochemistry and polymerase chain reaction (PCR) analyses revealed that the PTLDs were associated with macaca lymphocryptovirus as confirmed by double-labeling immunohistochemistry for CD20 and Epstein-Barr nuclear antigen 2 (EBNA-2), where the viral protein was located within the CD20+ neoplastic B cells. In sera from 3 distinct phases of the experimental life of the primates, testing by quantitative PCR revealed a progression of the viral load that paralleled the PTLD progression and no evidence of zoonotic transmission of porcine lymphotropic herpesvirus through xenoneuronal grafts. These data suggest that monitoring the variation of macaca lymphocryptovirus DNA in primates could be used as a possible early diagnostic tool for PTLD progression, allowing preemptive treatment such as immunosuppression therapy reduction
Spectroscopy of soft modes and quantum phase transitions in coupled electron bilayers
Strongly-correlated two-dimensional electrons in coupled semiconductor
bilayers display remarkable broken symmetry many-body states under accessible
and controllable experimental conditions. In the cases of continuous quantum
phase transitions soft collective modes drive the transformations that link
distinct ground states of the electron double layers. In this paper we consider
results showing that resonant inelastic light scattering methods detect soft
collective modes of the double layers and probe their evolution with
temperature and magnetic field. The light scattering experiments offer venues
of research of fundamental interactions and continuous quantum phase
transitions in low-dimensional electron liquids.Comment: 10 pages, 7 figure
Perancangan Sistem Pendukung Keputusan Pengangkatan Calon Kepala Sekolah Negeri Bandar Lampung Dengan Metode Saw
The progress of a school cannot be separated from the influence of how the ability of school principals in managing all the resources that exist in the school. Therefore we need qualified human resources in this case the teachers who have the potential and achievements of the school in order to become the head of a quality education can be realized. Until now the appointment of principals in both primary and secondary schools is based on an assessment for someone serving as a teacher. These procedures contain serious flaws. Decision Support System is a system that can help the Department of Education of Bandar Lampung in decisions determining the appropriate teachers for the office of State High School principal and improve the quality of the resulting decision of selection committee. The method used in the manufacture of this website is SAW (Simple Additive Weighting), System Development Life Cycle (SDLC) Waterfall models. Data was collected through observation and literature while the implementation of the waterfall model is described through system analysis, DFD, database table structure, and design input output. To design and create a website using Macromedia Dreamweaver MX , PHP programming language, MySQL database, and web server xampp
Observation of soft magnetorotons in bilayer quantum Hall ferromagnets
Inelastic light scattering measurements of low-lying collective excitations
of electron double layers in the quantum Hall state at total filling nu_T=1
reveal a deep magnetoroton in the dispersion of charge-density excitations
across the tunneling gap. The roton softens and sharpens markedly when the
phase boundary for transitions to highly correlated compressible states is
approached. The findings are interpreted with Hartree-Fock evaluations that
link soft magnetorotons to enhanced excitonic Coulomb interactions and to
quantum phase transitions in the ferromagnetic bilayers.Comment: ReVTeX4, 4 pages, 4 EPS figure
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