16,033 research outputs found

    Application of wavelets to singular integral scattering equations

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    The use of orthonormal wavelet basis functions for solving singular integral scattering equations is investigated. It is shown that these basis functions lead to sparse matrix equations which can be solved by iterative techniques. The scaling properties of wavelets are used to derive an efficient method for evaluating the singular integrals. The accuracy and efficiency of the wavelet transforms is demonstrated by solving the two-body T-matrix equation without partial wave projection. The resulting matrix equation which is characteristic of multiparticle integral scattering equations is found to provide an efficient method for obtaining accurate approximate solutions to the integral equation. These results indicate that wavelet transforms may provide a useful tool for studying few-body systems.Comment: 11 pages, 4 figure

    Cross Domain IW Threats to SOF Maritime Missions: Implications for U.S. SOF

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    As cyber vulnerabilities proliferate with the expansion of connected devices, wherein security is often forsaken for ease of use, Special Operations Forces (SOF) cannot escape the obvious, massive risk that they are assuming by incorporating emerging technologies into their toolkits. This is especially true in the maritime sector where SOF operates nearshore in littoral zones. As SOF—in support to the U.S. Navy— increasingly operate in these contested maritime environments, they will gradually encounter more hostile actors looking to exploit digital vulnerabilities. As such, this monograph comes at a perfect time as the world becomes more interconnected but also more vulnerable

    Cryptography, Passwords, Privacy, and the Fifth Amendment

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    Military-grade cryptography has been widely available at no cost for personal and commercial use since the early 1990s. Since the introduction of Pretty Good Privacy (PGP), more and more people encrypt files and devices, and we are now at the point where our smartphones are encrypted by default. While this ostensibly provides users with a high degree of privacy, compelling a user to provide a password has been interpreted by some courts as a violation of our Fifth Amendment protections, becoming an often insurmountable hurdle to law enforcement lawfully executing a search warrant. This paper will explore some of the issues around this complex legal and social issue, including the evolution in the use of digital cryptography and the evolving legal interpretations of privacy

    Evidence‐based guidelines support integrated disease management as the optimal model of haemophilia care

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/1/hae12997_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/2/hae12997.pd

    Evidence‐based guidelines support integrated disease management as the optimal model of haemophilia care

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/1/hae12997_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/122450/2/hae12997.pd

    Generalized Schrieffer-Wolff Formalism for Dissipative Systems

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    We present a formalized perturbation theory for Markovian open systems in the language of a generalized Schrieffer-Wolff (SW) transformation. A non-unitary rotation decouples the unper- turbed steady states from all fast degrees of freedom, in order to obtain an effective Liouvillian, that reproduces the exact low excitation spectrum of the system. The transformation is derived in a constructive way, yielding a perturbative expansion of the effective Liouville operator. The presented formalism realizes an adiabatic elimination of fast degrees of freedom to arbitrary orders in the perturbation. We exemplarily employ the SW formalism to two generic open systems and discuss general properties of the different orders of the perturbation.Comment: 11 pages, 1 figur

    Anti-melanocortin-4 receptor autoantibodies in obesity

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    Background: The melanocortin-4 receptor (MC4R) is part of an important pathway regulating energy balance. Here we report the existence of autoantibodies (autoAbs) against the MC4R in sera of obese patients. Methods: The autoAbs were detected after screening of 216 patients' sera by using direct and inhibition ELISA with an N-terminal sequence of the MC4R. Binding to the native MC4R was evaluated by flow cytometry and pharmacological effects by measuring adenylyl cyclase activity. Results: Positive results in all tests were obtained in patients with overweight or obesity (prevalence: 3.6%) but not in normal weight patients. The selective binding properties of anti-MC4R autoAbs were confirmed by surface plasmon resonance and by immunoprecipitation with the native MC4R. Finally it was demonstrated that these autoAbs increased food intake in rats after passive transfer via intracerebroventricular injection. Conclusion: These observations suggest that inhibitory anti-MC4R autoAbs might contribute to the development of obesity in a small subpopulation of patients

    Extinction Rates for Fluctuation-Induced Metastabilities : A Real-Space WKB Approach

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    The extinction of a single species due to demographic stochasticity is analyzed. The discrete nature of the individual agents and the Poissonian noise related to the birth-death processes result in local extinction of a metastable population, as the system hits the absorbing state. The Fokker-Planck formulation of that problem fails to capture the statistics of large deviations from the metastable state, while approximations appropriate close to the absorbing state become, in general, invalid as the population becomes large. To connect these two regimes, a master equation based on a real space WKB method is presented, and is shown to yield an excellent approximation for the decay rate and the extreme events statistics all the way down to the absorbing state. The details of the underlying microscopic process, smeared out in a mean field treatment, are shown to be crucial for an exact determination of the extinction exponent. This general scheme is shown to reproduce the known results in the field, to yield new corollaries and to fit quite precisely the numerical solutions. Moreover it allows for systematic improvement via a series expansion where the small parameter is the inverse of the number of individuals in the metastable state

    A mid-IR survey of the L 1641-N region with ISOCAM

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    We present an analysis of the L 1641 outflow region using broad-band and narrow-band imaging data at mid-infrared wavelengths from ISOCAM. We detect a total of 34 sources in the 7.657.65^{\prime} x 8.408.40^{\prime} region covered by the broad-band filters. Four of these sources have no reported detection in previous studies of the region. We find that the source previously identified as the near-IR counter-part to the IRAS detected point-source (IRAS 05338-0624) is not the brightest source in the wavelength region of the IRAS 12 \micron\ filter. We find instead that a nearby object (within the beam of IRAS and not detected at near-IR wavelengths) outshines all others sources in the area by a factor of \sim2. We submit that this source is likely to be the IRAS detected point source. A comparison of the near-IR (J-H vs H-K) and mid-IR (J-K vs [6.7 um]-[14 um]) color-color plots shows only four sources with excess emission at near-IR wavelengths, but atleast 85% of all sources show excess emission at mid-IR wavelengths. The CVF spectra suggest a range of evolutionary status in the program stars ranging from embedded YSOs to the young disks. When combined with optical and near-IR age estimates, these results show active current star-formation in the region that has been on-going for at least 2 Myr.Comment: Submitted to ApJ. Abstracted edited for arXiv submission Replaced by version accepted by Ap
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