1,066 research outputs found

    The Department of Consumers

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    In 1872, Congress began protecting the American consumer by enacting legislation to prevent mail fraud. From this modest beginning, the consumer protection activities of the federal government have proliferated until today there are at least 33 government agencies engaged in 296 consumer protection activities. In 1961, the estimated annual expenditures by the federal government for direct consumer protection activities totaled 272 million dollars and the number of full-time federal employees engaged in such activities was almost 22,000. Expenditures for consumer advancement, a broader concept, were estimated at 681 million dollars in 1961 and the number of full time federal employees assigned to such work was nearly 43,000. Current figures for such expenditures and employees would surely be substantially greater. This vast expenditure of money and time was not coordinated or administered by any single department or agency of the federal government. The activities were conducted independently except when independent federal agencies, in their own discretion, found it advisable to consult among themselves

    Anisotropic k-essence cosmologies

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    We investigate a Bianchi type-I (BTI) cosmology with k essence and find the set of models which dissipate the initial anisotropy. There are cosmological models with extended tachyon fields and k essence having constant bariotropic index. We obtain the conditions leading to a regular bounce of the average geometry and the residual anisotropy on the bounce. For constant potential, we develop purely kinetic k-essence models which are dust dominated in their early stages, dissipate the initial anisotropy and end in a stable de Sitter accelerated expansion scenario. We show that linear k field and polynomial kinetic function models evolve asymptotically to Friedmann-Robertson-Walker (FRW) cosmologies. The linear case is compatible with an asymptotic potential interpolating between VlϕγlV_l\propto \phi^{-\gamma_l}, in the shear dominated regime, and Vlϕ2V_l\propto\phi^{-2} at late time. In the polynomial case, the general solution contains cosmological models with an oscillatory average geometry. For linear k essence, we find the general solution in the BTI cosmology when the k field is driven by an inverse square potential. This model shares the same geometry than a quintessence field driven by an exponential potential.Comment: 19 pages, REVTeX

    Multi-frequency and multi-attribute GPR data fusion based on 2-D wavelet transform

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    High frequency GPR signals offer high resolution while low frequency GPR signals offer greater depth of penetration. Effective fusion of multiple frequencies can combine the advantages of both. In addition, GPR attribute analysis can improve subsurface imaging, but a single attribute can only partly highlight details of different physical and geometrical properties of subsurface potential targets. In order to overcome these challenges, we implement an advanced multi-frequency and multi-attribute GPR data fusion approach based on 2-D wavelet transform utilizing a dynamic fusion weight scheme derived from edge detection algorithm, which is tested on data from a small glacier in the north-eastern Alps by 250 & 500 MHz central frequency antennas. Besides, information entropy and spatial frequency are developed as quantitative evaluation parameters to analyze the fusion outcomes. The results demonstrate that the proposed approach can enhance the efficiency and scope of GPR data interpretation in an automatic and objective way

    Anyons as quon particles

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    The momentum operator representation of nonrelativistic anyons is developed in the Chern - Simons formulation of fractional statistics. The connection between anyons and the q-deformed bosonic algebra is established.Comment: 10 pages,Late

    The QCD/SM Working Group: Summary Report

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    This Report documents the results obtained by the Working Group on Quantum ChromoDynamics and the Standard Model for the Workshop ``Physics at TeV Colliders'', Les Houches, France, 21 May - 1 June 2001. The account of uncertainties in Parton Distribution Functions is reviewed. Progresses in the description of multiparton final states at Next-to-Leading Order and the extension of calculations for precision QCD observables beyond this order are summarized. Various issues concerning the relevance of resummation for observables at TeV colliders is examined. Improvements to algorithms of jet reconstruction are discussed and predictions for diphoton and photon pi-zero production at the LHC are made for kinematic variables of interest regarding searches for a Higgs boson decaying into two photons. Finally, several improvements implemented in Monte-Carlo event generators are documented

    An ATM/Chk2-mediated DNA damage responsive signaling pathway suppresses Epstein-Barr virus transformation of primary human B cells

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    SummaryEpstein-Barr virus (EBV), an oncogenic herpesvirus that causes human malignancies, infects and immortalizes primary human B cells in vitro into indefinitely proliferating lymphoblastoid cell lines, which represent a model for EBV-induced tumorigenesis. The immortalization efficiency is very low, suggesting that an innate tumor suppressor mechanism is operative. We identify the DNA damage response (DDR) as a major component of the underlying tumor suppressor mechanism. EBV-induced DDR activation was not due to lytic viral replication, nor did the DDR marks colocalize with latent episomes. Rather, a transient period of EBV-induced hyperproliferation correlated with DDR activation. Inhibition of the DDR kinases ATM and Chk2 markedly increased transformation efficiency of primary B cells. Further, the viral latent oncoprotein EBNA3C was required to attenuate the EBV-induced DDR. We propose that heightened oncogenic activity in early cell divisions activates a growth-suppressive DDR that is attenuated by viral latency products to induce cell immortalization

    Two-Loop Quantum Corrections of Scalar QED with Non-Minimal Chern-Simons Coupling

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    We investigate two-loop quantum corrections to non-minimally coupled Maxwell-Chern-Simons theory. The non-minimal gauge interaction represents the magnetic moment interaction between the charged scalar and the electromagnetic field. We show that the one-loop renormalizability of the theory found in previous work does not survive to the two-loop level. However, with an appropriate choice of the non-minimal coupling constant, it is possible to renormalize the two-loop effective potential and hence render it potentially useful for a detailed analysis of spontaneous symmetry breaking induced by radiative corrections.Comment: 29 pages, including 21 figures. One author added, some formulae corrected and references adde

    Planar QED at finite temperature and density: Hall conductivity, Berry's phases and minimal conductivity of graphene

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    We study 1-loop effects for massless Dirac fields in two spatial dimensions, coupled to homogeneous electromagnetic backgrounds, both at zero and at finite temperature and density. In the case of a purely magnetic field, we analyze the relationship between the invariance of the theory under large gauge transformations, the appearance of Chern-Simons terms and of different Berry's phases. In the case of a purely electric background field, we show that the effective Lagrangian is independent of the chemical potential and of the temperature. More interesting: we show that the minimal conductivity, as predicted by the quantum field theory, is the right multiple of the conductivity quantum and is, thus, consistent with the value measured for graphene, with no extra factor of pi in the denominator.Comment: 27 pages, no figures. Minor misprints corrected. Final version, to appear in J. Phys. A: Math. Ge
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