3,104 research outputs found

    Sharp eigenvalue enclosures for the perturbed angular Kerr-Newman Dirac operator

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    A certified strategy for determining sharp intervals of enclosure for the eigenvalues of matrix differential operators with singular coefficients is examined. The strategy relies on computing the second order spectrum relative to subspaces of continuous piecewise linear functions. For smooth perturbations of the angular Kerr-Newman Dirac operator, explicit rates of convergence due to regularity of the eigenfunctions are established. Existing benchmarks are validated and sharpened by several orders of magnitude in the unperturbed setting.Comment: 27 pages, 2 figures, 5 tables. Some errors fixe

    Studying melanin and lipofuscin in RPE cell culture models

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    The retinal pigment epithelium contains three major types of pigment granules; melanosomes, lipofuscin and melanolipofuscin. Melanosomes in the retinal pigment epithelium (RPE) are formed during embryogenesis and mature during early postnatal life while lipofuscin and melanolipofuscin granules accumulate as a function of age. The difficulty in studying the formation and consequences of melanosomes and lipofuscin granules in RPE cell culture is compounded by the fact that these pigment granules do not normally occur in established RPE cell lines and pigment granules are rapidly lost in adult human primary culture. This review will consider options available for overcoming these limitations and permitting the study of melanosomes and lipofuscin in cell culture and will briefly evaluate the advantages and disadvantages of the different protocols

    Non-abelian D=11 Supermembrane

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    We obtain a U(M) action for supermembranes with central charges in the Light Cone Gauge (LCG). The theory realizes all of the symmetries and constraints of the supermembrane together with the invariance under a U(M) gauge group with M arbitrary. The worldvolume action has (LCG) N=8 supersymmetry and it corresponds to M parallel supermembranes minimally immersed on the target M9xT2 (MIM2). In order to ensure the invariance under the symmetries and to close the corresponding algebra, a star-product determined by the central charge condition is introduced. It is constructed with a nonconstant symplectic two-form where curvature terms are also present. The theory is in the strongly coupled gauge-gravity regime. At low energies, the theory enters in a decoupling limit and it is described by an ordinary N=8 SYM in the IR phase for any number of M2-branes.Comment: Contribution to the Proceedings of the Dubna International SQS'09 Workshop ("Supersymmetries and Quantum Symmetries-2009", July 29 - August 3, 2009. 12pg, Late

    Missing children: risks, repeats and responses

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    Investigating reports of missing children is a major source of demand for the police in the UK. Repeat disappearances are common, can indicate underlying vulnerabilities and have been linked with various forms of exploitation and abuse. Inspired by research on repeat victimisation, this paper examines the prevalence and temporal patterns of repeat missing episodes by children, as well as the characteristics of those involved. Using data on all missing children incidents recorded by one UK police service in 2015 (n = 3352), we find that: (a) 75% of missing incidents involving children were repeats, i.e. attributed to children who had already been reported missing in 2015; (b) a small proportion of repeatedly missing children (n = 59; 4%) accounted for almost a third of all missing children incidents (n = 952, 28%); (c) over half of all first repeat disappearances occurred within four weeks of an initial police recorded missing episode; and (d) children recorded as missing ten times or more over the one year study period were significantly more likely than those recorded missing once to be teenagers, in the care system or to have drug and/or alcohol dependencies. We conclude by discussing the implications of our findings for future research and the prevention of repeat disappearances by childre

    Extraction efficiency of drifting electrons in a two-phase xenon time projection chamber

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    We present a measurement of the extraction efficiency of quasi-free electrons from the liquid into the gas phase in a two-phase xenon time-projection chamber. The measurements span a range of electric fields from 2.4 to 7.1 kV/cm in the liquid xenon, corresponding to 4.5 to 13.1 kV/cm in the gaseous xenon. Extraction efficiency continues to increase at the highest extraction fields, implying that additional charge signal may be attained in two-phase xenon detectors through careful high-voltage engineering of the gate-anode region

    Geomorphic and geological constraints on the active normal faulting of the Gediz (AlaÅŸehir) Graben, Western Turkey.

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    The Gediz (Alaşehir) Graben is located in the highly tectonically active region of Western Turkey. Extension due to regional geodynamic controls has resulted in a broadly two-phase evolution of the graben; firstly, low-angle normal faulting relating to the exhumation of the Menderes Massif metamorphic core complex took place between 16 - 2.6 Ma. Secondly, high-angle normal faulting initiated ~ 2 Ma forming the Gediz and other E-W trending grabens in the region. Here we quantify the throw rate along the fault array over the last 2.6, 2 and 0.7 Ma using structural and geological constraints, along with analysis of topographic relief as a proxy for footwall uplift. We derive, for the first time, time averaged rates of fault motion from 0.4 mm/yr to 1.3 mm/yr along the strike of the Gediz Graben, with variation in throw-rate associated with the geometry of individual fault strands. Patterns in throw-rate along strike of the graben bounding fault array also suggest that the fault segments have become linked during the last 2.6 - 2 Ma, possibly at 0.8 – 0.7 Ma. Furthermore, these data suggest that an earthquake occurring along the graben bounding fault could have a maximum predicted Mw of 6.3 - 7.6

    On Approximation of the Eigenvalues of Perturbed Periodic Schrodinger Operators

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    This paper addresses the problem of computing the eigenvalues lying in the gaps of the essential spectrum of a periodic Schrodinger operator perturbed by a fast decreasing potential. We use a recently developed technique, the so called quadratic projection method, in order to achieve convergence free from spectral pollution. We describe the theoretical foundations of the method in detail, and illustrate its effectiveness by several examples.Comment: 17 pages, 2 tables and 2 figure

    Attitudes and Behaviors of International Air Travelers Toward Pandemic Influenza

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112298/1/j.1708-8305.2011.00500.x.pd

    Calibration of a two-phase xenon time projection chamber with a 37^{37}Ar source

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    We calibrate a two-phase xenon detector at 0.27 keV in the charge channel and at 2.8 keV in both the light and charge channels using a 37^{37}Ar source that is directly released into the detector. We map the light and charge yields as a function of electric drift field. For the 2.8 keV peak, we calculate the Thomas-Imel box parameter for recombination and determine its dependence on drift field. For the same peak, we achieve an energy resolution, Eσ/EmeanE_{\sigma}/E_{mean}, between 9.8% and 10.8% for 0.1 kV/cm to 2 kV/cm electric drift fields.Comment: 12 pages, 7 figure

    Cascading the use of Web 2.0 technology in secondary schools in the United Kingdom: identifying the barriers beyond pre-service training

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    This paper reports on research that took place at Nottingham Trent University and Sheffield Hallam University, United Kingdom, over two years. The research focuses on the use of Web 2.0 technology, specifically web logs, with pre-service teachers, both during their university programme and the first year of teaching as full-time newly qualified teachers (NQTs). The purpose of this research was to add a developing body of knowledge by identifying whether technology used by pre-service teachers during their training course can be cascaded into their practice once qualified. Key findings identify a number of enablers and barriers to cascading technology in the classroom; these include curriculum time, pupil skills and support. The research concludes that early professional support and development should be on-going and assumptions about new teachers as champions of cascading innovative use of Web 2 technologies into their practice as NQTs may be over optimisti
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