29,483 research outputs found

    A pp-adic RanSaC algorithm for stereo vision using Hensel lifting

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    A pp-adic variation of the Ran(dom) Sa(mple) C(onsensus) method for solving the relative pose problem in stereo vision is developped. From two 2-adically encoded images a random sample of five pairs of corresponding points is taken, and the equations for the essential matrix are solved by lifting solutions modulo 2 to the 2-adic integers. A recently devised pp-adic hierarchical classification algorithm imitating the known LBG quantisation method classifies the solutions for all the samples after having determined the number of clusters using the known intra-inter validity of clusterings. In the successful case, a cluster ranking will determine the cluster containing a 2-adic approximation to the "true" solution of the problem.Comment: 15 pages; typos removed, abstract changed, computation error remove

    Mumford dendrograms and discrete p-adic symmetries

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    In this article, we present an effective encoding of dendrograms by embedding them into the Bruhat-Tits trees associated to pp-adic number fields. As an application, we show how strings over a finite alphabet can be encoded in cyclotomic extensions of Qp\mathbb{Q}_p and discuss pp-adic DNA encoding. The application leads to fast pp-adic agglomerative hierarchic algorithms similar to the ones recently used e.g. by A. Khrennikov and others. From the viewpoint of pp-adic geometry, to encode a dendrogram XX in a pp-adic field KK means to fix a set SS of KK-rational punctures on the pp-adic projective line P1\mathbb{P}^1. To P1S\mathbb{P}^1\setminus S is associated in a natural way a subtree inside the Bruhat-Tits tree which recovers XX, a method first used by F. Kato in 1999 in the classification of discrete subgroups of PGL2(K)\textrm{PGL}_2(K). Next, we show how the pp-adic moduli space M0,n\mathfrak{M}_{0,n} of P1\mathbb{P}^1 with nn punctures can be applied to the study of time series of dendrograms and those symmetries arising from hyperbolic actions on P1\mathbb{P}^1. In this way, we can associate to certain classes of dynamical systems a Mumford curve, i.e. a pp-adic algebraic curve with totally degenerate reduction modulo pp. Finally, we indicate some of our results in the study of general discrete actions on P1\mathbb{P}^1, and their relation to pp-adic Hurwitz spaces.Comment: 14 pages, 6 figure

    Redshifts and Luminosities for 112 Gamma Ray Bursts

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    Two different luminosity indicators have recently been proposed for Gamma Ray Bursts that use gamma-ray observations alone. They relate the burst luminosity (L) with the time lag between peaks in hard and soft energies, and the spikiness or variability of the burst's light curve (V). These relations are currently justified and calibrated with only 6 or 7 bursts with known red shifts. We have examined BATSE data for the lag and V for 112 bursts. (1) A strong correlation between the lag and V exists, and it is exactly as predicted from the two proposed relations. This is proof that both luminosity indicators are reliable. (2) GRB830801 is the all-time brightest burst, yet with a small V and a large lag, and hence is likely the closest known event being perhaps as close as 3.2 Mpc. (3) We have combined the luminosities as derived from both indicators as a means to improve the statistical and systematic accuracy when compared with the accuracy from either method alone. The result is a list of 112 bursts with good luminosities and hence red shifts. (4) The burst averaged hardness ratio rises strongly with the luminosity of the burst. (5) The burst luminosity function is a broken power law, with the break at L = 2x10^{52} erg/s. The luminosity function has power law indices of -2.8+-0.2 above the break and -1.7+-0.1 below the break. (6) The number density of GRBs varies with red shift roughly as (1+z)^(2.5+-0.3) between 0.2<z<5. Excitingly, this result also provides a measure of the star formation rate out to z~5 with no effects from reddening, and the rate is rising uniformly for red shifts above 2.Comment: 13 pages, 4 figures, submitted to ApJLet

    Determination of value of bovine respiratory disease control using a remote early disease identification system compared with conventional methods of metaphylaxis and visual observations

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    Citation: White, B. J., Amrine, D. E., & Goehl, D. R. (2015). Determination of value of bovine respiratory disease control using a remote early disease identification system compared with conventional methods of metaphylaxis and visual observations. Journal of Animal Science, 93(8), 4115-4122. doi:10.2527/jas2015-9079Mitigation of the deleterious effects of bovine respiratory disease (BRD) is an important issue in the cattle industry. Conventional management of calves at high risk for BRD often includes mass treatment with antimicrobials at arrival followed by visual observation for individual clinical cases. These methods have proven effective; however, control program efficacy is influenced by the accuracy of visual observation. A remote early disease identification (REDI) system has been described that monitors cattle behavior to identify potential BRD cases. The objective of this research was to compare health and performance outcomes using either traditional BRD control (visual observation and metaphylaxis) or REDI during a 60-d postarrival phase in high-risk beef calves. The randomized controlled clinical trial was performed in 8 replicates at 3 different facilities over a 19-mo period. In each replicate, a single load of calves was randomly allocated to receive either conventional management (CONV; total n = 8) or REDI (total n = 8) as the method for BRD control. Cattle were monitored with each diagnostic method for the first 30 d on feed and performance variables were collected until approximately 60 d after arrival. Statistical differences (P 0.10) in risk of BRD treatment and REDI calves were not administered antimicrobials at arrival; therefore, REDI calves had a lower (P < 0.01) average number of doses of antimicrobials/calf (0.75 +/- 0.1 doses) compared with CONV calves (1.67 +/- 0.1 doses). In this trial, the REDI system was comparable to conventional management with the potential advantages of earlier BRD diagnosis and decreased use of antimicrobials. Further research should be performed to evaluate the longer-term impacts of the 2 systems

    Vibration limiting of rotors by feedback control

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    Experimental findings of a three mass rotor with four channels of feedback control are reported. The channels are independently controllable with force being proportional to the velocity and/or instantaneous displacement from equilibrium of the shaft at the noncontacting probe locations (arranged in the vertical and horizontal attitudes near the support bearings). The findings suggest that automatic feedback control of rotors is feasible for limiting certain vibration levels. Control of one end of a rotor does afford some predictable vibration limiting of the rotor at the other end

    A Statistical Treatment of the Gamma-Ray Burst "No Host Galaxy" Problem: II. Energies of Standard Candle Bursts

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    With the discovery that the afterglows after some bursts are coincident with faint galaxies, the search for host galaxies is no longer a test of whether bursts are cosmological, but rather a test of particular cosmological models. The methodology we developed to investigate the original "no host galaxy" problem is equally valid for testing different cosmological models, and is applicable to the galaxies coincident with optical transients. We apply this methodology to a family of models where we vary the total energy of standard candle bursts. We find that total isotropic energies of E<2e52~erg are ruled out while log(E)~53 erg is favored.Comment: To appear in Ap.J., 514, 15 pages + 7 figures, AASTeX 4.0. Revisions are: additional author, updated data, and minor textual change

    Theory of the Ramsey spectroscopy and anomalous segregation in ultra-cold rubidium

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    The recent anomalous segregation experiment of Lewandowski et al. (PRL, 88, 070403, 2002) shows dramatic, rapid internal state segregation for two hyperfine levels of rubidium. We simulate an effective one dimensional model of the system for experimental parameters and find reasonable agreement with the data. The Ramsey frequency is found to be insensitive to the decoherence of the superposition, and is only equivalent to the interaction energy shift for a pure superposition. A Quantum Boltzmann equation describing collisions is derived using Quantum Kinetic Theory, taking into account the different scattering lengths of the internal states. As spin-wave experiments are likely to be attempted at lower temperatures we examine the effect of degeneracy on decoherence by considering the recent experiment of Lewandowski et al. where degeneracy is around 10%. We also find that the segregation effect is only possible when transport terms are included in the equations of motion, and that the interactions only directly alter the momentum distributions of the states. The segregation or spin wave effect is thus entirely due to coherent atomic motion as foreseen in the experimental reportComment: 26 pages, 4 figures, to be published in J. Phys.

    Evolutionary Timescale of the DAV G117-B15A: The Most Stable Optical Clock Known

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    We observe G117-B15A, the most precise optical clock known, to measure the rate of change of the main pulsation period of this blue-edge DAV white dwarf. Even though the obtained value is only within 1 sigma, Pdot = (2.3 +/- 1.4) x 10^{-15} s/s, it is already constraining the evolutionary timescale of this cooling white dwarf star.Comment: Accepted for publication in ApJ

    Ranking Templates for Linear Loops

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    We present a new method for the constraint-based synthesis of termination arguments for linear loop programs based on linear ranking templates. Linear ranking templates are parametrized, well-founded relations such that an assignment to the parameters gives rise to a ranking function. This approach generalizes existing methods and enables us to use templates for many different ranking functions with affine-linear components. We discuss templates for multiphase, piecewise, and lexicographic ranking functions. Because these ranking templates require both strict and non-strict inequalities, we use Motzkin's Transposition Theorem instead of Farkas Lemma to transform the generated \exists\forall-constraint into an \exists-constraint.Comment: TACAS 201
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