653 research outputs found

    Correspondence

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    Orbital evolution of a particle around a black hole: II. Comparison of contributions of spin-orbit coupling and the self force

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    We consider the evolution of the orbit of a spinning compact object in a quasi-circular, planar orbit around a Schwarzschild black hole in the extreme mass ratio limit. We compare the contributions to the orbital evolution of both spin-orbit coupling and the local self force. Making assumptions on the behavior of the forces, we suggest that the decay of the orbit is dominated by radiation reaction, and that the conservative effect is typically dominated by the spin force. We propose that a reasonable approximation for the gravitational waveform can be obtained by ignoring the local self force, for adjusted values of the parameters of the system. We argue that this approximation will only introduce small errors in the astronomical determination of these parameters.Comment: 11 pages, 7 figure

    Perfect state distinguishability and computational speedups with postselected closed timelike curves

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    Bennett and Schumacher's postselected quantum teleportation is a model of closed timelike curves (CTCs) that leads to results physically different from Deutsch's model. We show that even a single qubit passing through a postselected CTC (P-CTC) is sufficient to do any postselected quantum measurement, and we discuss an important difference between "Deutschian" CTCs (D-CTCs) and P-CTCs in which the future existence of a P-CTC might affect the present outcome of an experiment. Then, based on a suggestion of Bennett and Smith, we explicitly show how a party assisted by P-CTCs can distinguish a set of linearly independent quantum states, and we prove that it is not possible for such a party to distinguish a set of linearly dependent states. The power of P-CTCs is thus weaker than that of D-CTCs because the Holevo bound still applies to circuits using them regardless of their ability to conspire in violating the uncertainty principle. We then discuss how different notions of a quantum mixture that are indistinguishable in linear quantum mechanics lead to dramatically differing conclusions in a nonlinear quantum mechanics involving P-CTCs. Finally, we give explicit circuit constructions that can efficiently factor integers, efficiently solve any decision problem in the intersection of NP and coNP, and probabilistically solve any decision problem in NP. These circuits accomplish these tasks with just one qubit traveling back in time, and they exploit the ability of postselected closed timelike curves to create grandfather paradoxes for invalid answers.Comment: 15 pages, 4 figures; Foundations of Physics (2011

    Gravitational radiation from a particle in circular orbit around a black hole. VI. Accuracy of the post-Newtonian expansion

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    A particle of mass ÎŒ\mu moves on a circular orbit around a nonrotating black hole of mass MM. Under the assumption ÎŒâ‰ȘM\mu \ll M the gravitational waves emitted by such a binary system can be calculated exactly numerically using black-hole perturbation theory. If, further, the particle is slowly moving, then the waves can be calculated approximately analytically, and expressed in the form of a post-Newtonian expansion. We determine the accuracy of this expansion in a quantitative way by calculating the reduction in signal-to-noise ratio incurred when matched filtering the exact signal with a nonoptimal, post-Newtonian filter.Comment: 5 pages, ReVTeX, 1 figure. A typographical error was discovered in the computer code used to generate the results presented in the paper. The corrected results are presented in an Erratum, which also incorporates new results, obtained using the recently improved post-Newtonian calculations of Tanaka, Tagoshi, and Sasak

    Pancreatic lipase immunoreactivity in serum of dogs with diabetic ketoacidosis

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    BACKGROUND : Diabetic ketoacidosis (DKA) is a relatively common endocrine disorder in dogs and is routinely associated with concurrent pancreatic injury. OBJECTIVES : The aims of this study were to determine the prevalence of pancreatic injury in dogs with DKA based on measurement of pancreatic lipase immunoreactivity in serum (PLI); compare demographic, clinicopathologic, and ultrasonographic findings in dogs with and without evidence of concurrent pancreatic injury; determine the impact of pancreatic injury on duration of hospitalization and short-term outcome. ANIMALS : One hundred and nineteen dogs with DKA with or without concurrent pancreatic injury. METHODS : Retrospective study. Dogs with DKA were divided into three groups on the basis of PLI results: positive for pancreatic injury (PLIpos), negative for pancreatic injury (PLIneg), and not tested (PLIna). Demographics, clinicopathologic test results, findings on abdominal ultrasonography (AUS), duration of hospitalization, and short-term outcome were compared between the three groups. RESULTS : Based on serum PLI activity, 45 dogs (73%) with DKA had evidence of concurrent pancreatic injury. Median total carbon dioxide was significantly lower in the PLIpos dogs compared to the PLIneg dogs. There was fair agreement (j = 0.26) between serum PLI activity and AUS. Evidence of pancreatic injury was not associated with significantly longer periods of hospitalization (PLIpos median 6 days, range 4–7 days, PLIneg median 4 days, range 3–6 days) and did not influence short-term outcome (PLIpos failure to survive to discharge 11/45, 24%, PLIneg failure to survive to discharge 2/17, 12%). CLINICAL IMPORTANCE : Concurrent pancreatic injury is common in dogs with DKA, but did not affect prognosis in this population of dogs.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1939-1676hb2017Production Animal Studie

    Gravitational waves from eccentric compact binaries: Reduction in signal-to-noise ratio due to nonoptimal signal processing

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    Inspiraling compact binaries have been identified as one of the most promising sources of gravitational waves for interferometric detectors. Most of these binaries are expected to have circularized by the time their gravitational waves enter the instrument's frequency band. However, the possibility that some of the binaries might still possess a significant eccentricity is not excluded. We imagine a situation in which eccentric signals are received by the detector but not explicitly searched for in the data analysis, which uses exclusively circular waveforms as matched filters. We ascertain the likelihood that these filters, though not optimal, will nevertheless be successful at capturing the eccentric signals. We do this by computing the loss in signal-to-noise ratio incurred when searching for eccentric signals with those nonoptimal filters. We show that for a binary system of a given total mass, this loss increases with increasing eccentricity. We show also that for a given eccentricity, the loss decreases as the total mass is increased.Comment: 14 pages, 4 figures, ReVTeX; minor changes made after referee's comment

    Long-term perturbations due to a disturbing body in elliptic inclined orbit

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    In the current study, a double-averaged analytical model including the action of the perturbing body's inclination is developed to study third-body perturbations. The disturbing function is expanded in the form of Legendre polynomials truncated up to the second-order term, and then is averaged over the periods of the spacecraft and the perturbing body. The efficiency of the double-averaged algorithm is verified with the full elliptic restricted three-body model. Comparisons with the previous study for a lunar satellite perturbed by Earth are presented to measure the effect of the perturbing body's inclination, and illustrate that the lunar obliquity with the value 6.68\degree is important for the mean motion of a lunar satellite. The application to the Mars-Sun system is shown to prove the validity of the double-averaged model. It can be seen that the algorithm is effective to predict the long-term behavior of a high-altitude Martian spacecraft perturbed by Sun. The double-averaged model presented in this paper is also applicable to other celestial systems.Comment: 28 pages, 6 figure

    The Paranormal is (Still) Normal: The Sociological Implications of a Survey of Paranormal Experiences in Great Britain

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    Historically, there has been limited sociological interest in the paranormal and no systematic study of reported paranormal experiences. There are also few medium-to-large-scale survey results with nationally representative populations focusing on paranormal experiences. This paper provides details of an exploratory survey conducted in 2009 with a nationally representative sample of 4,096 adults aged 16 years and over across Great Britain. Our findings show that 37% of British adults report at least one paranormal experience and that women, those who are middle-aged or individuals resident in the South West are more likely to report such experiences. These results establish incidence levels of reported paranormal experiences in contemporary Britain. We argue also that they merit a more sustained sociological consideration of the paranormal. In this respect we renew and update the robust justification and call for serious research positioning the paranormal as a social phenomenon, originally proposed well over thirty years ago by Greeley (1975)

    Systems Biological Determination of the Epi-Genomic Structure Function Relation:

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    Despite our knowledge of the sequence of the human genome, the relation of its three-dimensional dynamic architecture with its function – the storage and expression of genetic information – remains one of the central unresolved issues of our age. It became very clear meanwhile that this link is crucial for the entire holistic function of the genome on all genomic coding levels from the DNA sequence to the entire chromosomes. To fulfil the dreams for better diagnostics and treatment in the 21st century (e.g. by gene therapy by inserting a gene into a new global context), we propose here in a unique interdisciplinary project to combine experiment with theory to analyze the (epi-)genomic structure function relationships within the dynamic organization of the -Globin locus, the Immuno Globin loci, and the Tumor Necrosis Factor Alpha regulated SAMD4 region in mouse and human active and inactive cell states, and their global genomic context. The project consists of five work packages (WP1-WP5) and corresponding tasks connected in a system biological approach with iterative use of data, modelling, simulation and experiments via a unique data sharing and visualization platform: In WP1 (LĂ€ngst, Rippe, Wedemann, Knoch/Grosfeld; T1-T5) to investigate nucleosomal association changes in relation to the DNA sequence and the activity of ATP-driven chromatin remodelling complexes, nucleosome positions will be determined by high-throughput sequencing. The resulting nucleosomal localization probability maps will be evaluated by a novel combination of analysis tools and innovative generic data ontologies. The relation to epigenetic modifications, to the activity of ATP-driven remodelling complexes and compaction degree of nucleosomes will be analysed to understand chromatin morphogenesis and fiber formation. In parallel, in WP2 (Grosveld/Knoch, Cook, Rippe, LĂ€ngst; T1-T3) we determine by high-throughput monitoring of intra/inter chromosomal contacts and architecture absolute DNA-DNA interaction probability maps for the individual loci and their global context using a novel chromosome conformation capture approach based on deep sequencing. From these the 3D conformation of the chromatin fiber and its higher-order folding into loops and loop clusters can be derived using algorithms recently developed by us. WP3 (Cook, Grosveld/Knoch, LĂ€ngst; T1-T5) focuses on the determination of transcription rates and structure by qRT-PCR, DNA and RNA fluorescence in situ hybridization using intronic probes and high-resolution laser-scanning and single molecule imaging with advanced image analysis tools. Transcription-dependent changes of active and inactive loci as well as rapid synchronous transcription alteration against the unchanged background is one main interest here. This will yield results in a detailed cartography of the structure-transcription-function dependency and its importance. To rationalize the experimental results theoretically, in WP4 (Wedemann Knoch/Grosveld, Rippe; T1-T3) simulations are made of nucleosomal structure, chromatin fiber conformation and chromosomal architecture using parallel and grid super-computers with ~10.000 CPUs. The impact of different nucleosomal positions and epigenetic modifications on the nucleosomal structure and the chromatin fiber conformation will be assessed by novel Monte Carlo approaches. To understand the higher-order architecture Brownian Dynamics simulations of entire cell nuclei with molecular re

    Ownership and control in a competitive industry

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    We study a differentiated product market in which an investor initially owns a controlling stake in one of two competing firms and may acquire a non-controlling or a controlling stake in a competitor, either directly using her own assets, or indirectly via the controlled firm. While industry profits are maximized within a symmetric two product monopoly, the investor attains this only in exceptional cases. Instead, she sometimes acquires a noncontrolling stake. Or she invests asymmetrically rather than pursuing a full takeover if she acquires a controlling one. Generally, she invests indirectly if she only wants to affect the product market outcome, and directly if acquiring shares is profitable per se. --differentiated products,separation of ownership and control,private benefits of control
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