548 research outputs found

    The Homeric poems as oral dictated texts

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    The more I understand the Southslavic poetry and the nature of the unity of the oral poem, the clearer it seems to me that the Iliad and the Odyssey are very exactly, as we have them, each one of them the rounded and finished work of a single singer…. I even figure to myself, just now, the moment when the author of the Odyssey sat and dictated his song, while another, with writing materials, wrote it down verse by verse, even in the way that our singers sit in the immobility of their thought, watching the motion of Nikola's hand across the empty page, when it will tell them it is the instant for them to speak the next verse

    Defective Transcriptional Programming of Effector CD8 T Cells in Aged Mice Is Cell-Extrinsic and Can Be Corrected by Administration of IL-12 and IL-18

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    In response to infection with intracellular microorganisms, old mice mobilize decreased numbers of antigen-specific CD8 T cells with reduced expression of effector molecules and impaired cytolytic activity. Molecular mechanisms behind these defects and the cell-intrinsic (affecting naïve CD8 T cells themselves) vs. extrinsic, microenvironmental origin of such defects remain unclear. Using reciprocal transfer experiments of highly purified naïve T cells from adult and old transgenic OT-1 mice, we decisively show that the dominant effect is cell-extrinsic. Naïve adult OT-1 T cells failed to expand and terminally differentiate in the old organism infected with Listeria-OVA. This defect was preceded by blunted expression of the master transcription factor T-bet and impaired glycolytic switch when T cells are primed in the old organism. However, both old and adult naïve CD8 T cells proliferated and produced effector molecules to a similar extent when stimulated in vitro with polyclonal stimuli, as well as when transferred into adult recipients. Multiple inflammatory cytokines with direct effects on T cell effector differentiation were decreased in spleens of old animals, particularly IL-12 and IL-18. Of note, in vivo treatment of mice with IL-12 and IL-18 on days 4–6 of Listeria infection reconstituted cytotoxic T cell response of aged mice to the level of adult. Therefore, critical cytokine signals which are underproduced in the old priming environment can restore proper transcriptional programming of old naïve CD8 T cells and improve immune defense against intracellular microorganisms

    Phase Fluctuations and Pseudogap Properties: Influence of Nonmagnetic Impurities

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    The presence of nonmagnetic impurities in a 2D ``bad metal'' depresses the superconducting Berezinskii-Kosterlitz-Thouless transition temperature, while leaving the pairing energy scale unchanged. Thus the region of the pseudogap non-superconducting phase, where the modulus of the order parameter is non-zero but its phase is random, and which opens at the pairing temperature is substantially bigger than for the clean system. This supports the premise that fluctuations in the phase of the order parameter can in principle describe the pseudogap phenomena in high-TcT_c materials over a rather wide range of temperatures and carrier densities. The temperature dependence of the bare superfluid density is also discussed.Comment: 11 pages, LaTeX, 1 EPS figure; final version to appear in Low.Temp.Phy

    Parity-Affected Superconductivity in Ultrasmall Metallic Grains

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    We investigate the breakdown of BCS superconductivity in {\em ultra}\/small metallic grains as a function of particle size (characterized by the mean spacing dd between discrete electronic eigenstates), and the parity (PP = even/odd) of the number of electrons on the island. Assuming equally spaced levels, we solve the parity-dependent BCS gap equation for the order parameter ΔP(d,T)\Delta_P (d,T). Both the T=0T=0 critical level spacing dc,Pd_{c,P} and the critical temperature Tc,P(d)T_{c,P} (d) at which ΔP=0\Delta_P = 0 are parity dependent, and both are so much smaller in the odd than the even case that these differences should be measurable in current experiments.Comment: 4 pages RevTeX, 1 encapsulated postscript figure, submitted to Physical Review Letter

    Parity Effect and Charge Binding Transition in Submicron Josephson Junction Arrays

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    We reconsider the issue of Berezinskii-Kosterlitz-Thouless (BKT) transition into an insulating state in the Coulomb-dominated Josephson junction arrays. We show that previously predicted picture of the Cooper-pair BKT transtion at T = T_2 is valid only under the condition that T_2 is considerably below the parity-effect temperature (which is usually almost 10 times below the value of superconductive transition temperature), and even in this case it is not a rigorous phase transition but only a crossover, whereas the real phase transition takes place at T_1 = T_2/4. Our theory is in agreement with available experimental data on Coulomb-dominated Josephson arrays and also sheds some light on the origin of unusual reentrant temperature dependence of resistivity in the array with nearly-criticial ratio of Coulomb to Josephson energies.Comment: 4 pages, Revtex, to be published in JETP Letters, April 9

    Examining the Link between Crime and Unemployment: A Time Series Analysis for Canada

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    We use national and regional Canadian data to analyse the relationship between economic activity (as reflected by the unemployment rate) and crime rates. Given potential aggregation bias, we disaggregate the crime data and look at the relationship between six different types of crimes rates and unemployment rate; we also disaggregate the data by region. We employ an error correction model in our analysis to test for short-run and long-run dynamics. We find no evidence of long-run relationship between crime and unemployment, when we look at both disaggregation by type of crime and disaggregation by region. Lack of evidence of a long-run relationship indicates we have no evidence of the motivation hypothesis. For selected types of property crimes, we find some evidence of a significant negative short-run relationship between crime and unemployment, lending support to the opportunity hypothesis. Inclusion of control variables in the panel analysis does not alter the findings, qualitatively or quantitatively
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