1,423 research outputs found

    The Local Velocity Anomaly

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    There is a velocity discontinuity at about 7 Mpc between the galaxies of the Local Sheet that are moving together with low internal velocity dispersion and the adjacent structures. The Local Sheet bounds the Local Void. The Local Sheet is determined to have a peculiar velocity of 260 km/s away from the center of the void. In order for this large velocity to be generated by an absence of gravity, the Local Void must be at least 45 Mpc in diameter and be very empty.Comment: Invited review, "Galaxies in the Local Volume", Sydney, 8-13 July, 2007. eds. B. Koribalski & H. Jerjen, Astrophys. & Space Sci. Proceed. 10 pages with 7 figure

    Study of the 3-Nucleon System: d+p Breakup Measurements at E_d = 80 MeV

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    This work was supported by the National Science Foundation Grant NSF PHY 81-14339 and by Indiana Universit

    Construction and evaluation of an expression vector allowing the stable expression of foreign antigens in a Salmonella typhimurium vaccine strain at toxic levels.

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    Salmonella strains have great potential as live carriers of heterologous antigens to induce immunity against a variety of infectious diseases. However, the amount of heterologous antigen required to induce an adequate immune response may be toxic for the bacterium and result in cell death, overattenuation or loss of expression of the heterologous antigen. To solve this problem an expression vector was developed with a strong promoter located on a DNA fragment which is inverted at random. Antigen is only expressed in one particular orientation of the promoter. Thus a bacterial population harbouring the plasmid will consist o

    Osteogenic tumour in Australopithecus sediba: Earliest hominin evidence for neoplastic disease

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    We describe the earliest evidence for neoplastic disease in the hominin lineage. This is reported from the type specimen of the extinct hominin Australopithecus sediba from Malapa, South Africa, dated to 1.98 million years ago. The affected individual was male and developmentally equivalent to a human child of 12 to 13 years of age. A penetrating lytic lesion affected the sixth thoracic vertebra. The lesion was macroscopically evaluated and internally imaged through phase-contrast X-ray synchrotron microtomography. A comprehensive differential diagnosis was undertaken based on gross- and micro-morphology of the lesion, leading to a probable diagnosis of osteoid osteoma. These neoplasms are solitary, benign, osteoid and bone-forming tumours, formed from well-vascularised connective tissue within which there is active production of osteoid and woven bone. Tumours of any kind are rare in archaeological populations, and are all but unknown in the hominin record, highlighting the importance of this discovery. The presence of this disease at Malapa predates the earliest evidence of malignant neoplasia in the hominin fossil record by perhaps 200 000 years.NCS201

    Low Complexity Regularization of Linear Inverse Problems

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    Inverse problems and regularization theory is a central theme in contemporary signal processing, where the goal is to reconstruct an unknown signal from partial indirect, and possibly noisy, measurements of it. A now standard method for recovering the unknown signal is to solve a convex optimization problem that enforces some prior knowledge about its structure. This has proved efficient in many problems routinely encountered in imaging sciences, statistics and machine learning. This chapter delivers a review of recent advances in the field where the regularization prior promotes solutions conforming to some notion of simplicity/low-complexity. These priors encompass as popular examples sparsity and group sparsity (to capture the compressibility of natural signals and images), total variation and analysis sparsity (to promote piecewise regularity), and low-rank (as natural extension of sparsity to matrix-valued data). Our aim is to provide a unified treatment of all these regularizations under a single umbrella, namely the theory of partial smoothness. This framework is very general and accommodates all low-complexity regularizers just mentioned, as well as many others. Partial smoothness turns out to be the canonical way to encode low-dimensional models that can be linear spaces or more general smooth manifolds. This review is intended to serve as a one stop shop toward the understanding of the theoretical properties of the so-regularized solutions. It covers a large spectrum including: (i) recovery guarantees and stability to noise, both in terms of â„“2\ell^2-stability and model (manifold) identification; (ii) sensitivity analysis to perturbations of the parameters involved (in particular the observations), with applications to unbiased risk estimation ; (iii) convergence properties of the forward-backward proximal splitting scheme, that is particularly well suited to solve the corresponding large-scale regularized optimization problem

    Superluminal pions in a hadronic fluid

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    We study the propagation of pions at finite temperature and finite chemical potential in the framework of the linear sigma model with 2 quark flavors and NcN_c colors. The velocity of massless pions in general differs from that of light. One-loop calculations show that in the chiral symmetry broken phase pions, under certain conditions, propagate faster than light.Comment: 8 pages, 3 figures included. Considerably revised, discussions expanded, one figure added, typos corrected, results unchanged. To be published in Phys. Rev.

    An Experimental Test of Charge Symmetry in n-p Scattering

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    Supported by the National Science Foundation and Indiana Universit

    Bladder neck mobility in continent nulliparous women

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    To evaluate the mobility of the vesical neck during coughing and valsalva in healthy nulliparous volunteers and to test the reliability of the technique applied. Design Clinical observational study. Setting Department of Obstetrics and Gynaecology, Cantonal Hospital Lucerne, Switzerland. Population Thirty-nine nulliparous volunteers. Methods Vesical neck motion was assessed with perineal ultrasound. Intra–abdominal pressure was controlled for with an intrarectal probe. Intra-rater reliability was evaluated. Results Vesical neck mobility was significantly lower during coughing (8 mm, SD 4 mm) than during valsalva (15 mm, SD 10 mm) ( P < 0.005 ). Between individuals mobility varied from 4 mm to 32 mm during coughing and from 2 mm to 31 mm during valsalva. Test-retest-studies showed a maximum difference between to tests during coughing of 4 mm and during valsalva of 5 mm. Conclusion The bladder neck is mobile in normal continent women and bladder neck mobility is lower during coughing than during Valsalva.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74987/1/j.1471-0528.2001.00066.x.pd

    Signatures of chaotic tunnelling

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    Recent experiments with cold atoms provide a significant step toward a better understanding of tunnelling when irregular dynamics is present at the classical level. In this paper, we lay out numerical studies which shed light on the previous experiments, help to clarify the underlying physics and have the ambition to be guidelines for future experiments.Comment: 11 pages, 9 figures, submitted to Phys. Rev. E. Figures of better quality can be found at http://www.phys.univ-tours.fr/~mouchet
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