741 research outputs found

    Cliophysics: Socio-political Reliability Theory, Polity Duration and African Political (In)stabilities

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    Quantification of historical sociological processes have recently gained attention among theoreticians in the effort of providing a solid theoretical understanding of the behaviors and regularities present in sociopolitical dynamics. Here we present a reliability theory of polity processes with emphases on individual political dynamics of African countries. We found that the structural properties of polity failure rates successfully capture the risk of political vulnerability and instabilities in which 87.50%, 75%, 71.43%, and 0% of the countries with monotonically increasing, unimodal, U-shaped and monotonically decreasing polity failure rates, respectively, have high level of state fragility indices. The quasi-U-shape relationship between average polity duration and regime types corroborates historical precedents and explains the stability of the autocracies and democracies.Comment: 4 pages, 3 figures, 1 tabl

    Neutrino Oscillations and the Supernova 1987A Signal

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    We study the impact of neutrino oscillations on the interpretation of the supernova (SN) 1987A neutrino signal by means of a maximum-likelihood analysis. We focus on oscillations between νe\overline\nu_e with νμ\overline\nu_\mu or ντ\overline\nu_\tau with those mixing parameters that would solve the solar neutrino problem. For the small-angle MSW solution (Δm2105eV2\Delta m^2\approx10^{-5}\,\rm eV^2, sin22Θ00.007\sin^22\Theta_0\approx0.007), there are no significant oscillation effects on the Kelvin-Helmholtz cooling signal; we confirm previous best-fit values for the neutron-star binding energy and average spectral νe\overline\nu_e temperature. There is only marginal overlap between the upper end of the 95.4\% CL inferred range of Eνe\langle E_{\overline\nu_e}\rangle and the lower end of the range of theoretical predictions. Any admixture of the stiffer νμ\overline\nu_\mu spectrum by oscillations aggravates the conflict between experimentally inferred and theoretically predicted spectral properties. For mixing parameters in the neighborhood of the large-angle MSW solution (Δm2105eV2\Delta m^2\approx10^{-5}\,\rm eV^2, sin22Θ00.7\sin^22\Theta_0\approx0.7) the oscillations in the SN are adiabatic, but one needs to include the regeneration effect in the Earth which causes the Kamiokande and IMB detectors to observe different νe\overline\nu_e spectra. For the solar vacuum solution (Δm21010eV2\Delta m^2\approx10^{-10}\,\rm eV^2, sin22Θ01\sin^22\Theta_0\approx1) the oscillations in the SN are nonadiabatic; vacuum oscillations take place between the SN and the detector. If either of the large-angle solutions were borne out by the upcoming round of solar neutrino experiments, one would have to conclude that the SN~1987A νμ\overline\nu_\mu and/or νe\overline\nu_e spectra had been much softer than predicted by currentComment: Final version with very minor wording changes, to be published in Phys. Rev.

    Resonant Spin-Flavor Conversion of Supernova Neutrinos and Deformation of the Electron Antineutrino Spectrum

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    The neutrino spin-flavor conversion of \bar\nu_e and \nu_\mu which is induced by the interaction of the Majorana neutrino magnetic moment and magnetic fields in the collapse-driven supernova is investigated in detail. We calculate the conversion probability by using the latest precollapse models of Woosley and Weaver (1995), and also those of Nomono and Hashimoto (1988), changing the stellar mass and metallicity in order to estimate the effect of the astrophysical uncertainties. Contour maps of the conversion probability are given for all the models as a function of neutrino mass squared difference and the neutrino magnetic moment times magnetic fields. It is shown that in the solar metallicity models some observational effects are expected with \Delta m^2 = 10^{-5}--10^{-1} [eV^2] and \mu_\nu >~ 10^{-12} (10^9 G / B_0) [\mu_B], where B_0 is the strength of the magnetic fields at the surface of the iron core. We also find that although the dependence on the stellar models or stellar mass is not so large, the metallicity of precollapse stars has considerable effects on this conversion. Such effects may be seen in a supernova in the Large or Small Magellanic Clouds, and should be taken into account when one considers an upper bound on \mu_\nu from the SN1987A data.Comment: 19 pages, LaTeX, using revtex. To appear in Phys. Rev. D. 16 figures attatche

    Dirac neutrino magnetic moment and a possible time evolution of the neutrino signal from a supernova

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    We analyze the influence of neutrino helicity conversion, νLνR\nu_L \to \nu_R, on the neutrino flux from a supernova caused by the interaction of the Dirac neutrino magnetic moment with a magnetic field. We show that if the neutrino has a magnetic moment in the interval 1013μB<μν<1012μB10^{-13} \, \mu_{\rm B} < \mu_\nu < 10^{-12} \, \mu_{\rm B} and provided that a magnetic field of 10131014\sim 10^{13} - 10^{14} G exists in the supernova envelope, a peculiar kind of time evolution of the neutrino signal from the supernova caused by the resonance transition νLνR\nu_L \to \nu_R in the magnetic field of the envelope can appear. If a magnetar with a poloidal magnetic field is formed in a supernova explosion, then the neutrino signal could have a pulsating behavior, i.e., a kind of a neutrino pulsar could be observed, when it rotates around an axis that does not coincide with its magnetic moment and when the orientation of its rotation axis is favourable for our observation.Comment: 9 pages, LaTeX, 2 EPS figures, based on the talk presented by A.V. Kuznetsov at the XVI International Seminar Quarks'2010, Kolomna, Moscow Region, June 6-12, 2010, to appear in the Proceeding

    Potential for Supernova Neutrino Detection in MiniBooNE

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    The MiniBooNE detector at Fermilab is designed to search for νμνe\nu_\mu \to \nu_e oscillation appearance at Eν1GeVE_\nu \sim 1 {\rm GeV} and to make a decisive test of the LSND signal. The main detector (inside a veto shield) is a spherical volume containing 0.680 ktons of mineral oil. This inner volume, viewed by 1280 phototubes, is primarily a \v{C}erenkov medium, as the scintillation yield is low. The entire detector is under a 3 m earth overburden. Though the detector is not optimized for low-energy (tens of MeV) events, and the cosmic-ray muon rate is high (10 kHz), we show that MiniBooNE can function as a useful supernova neutrino detector. Simple trigger-level cuts can greatly reduce the backgrounds due to cosmic-ray muons. For a canonical Galactic supernova at 10 kpc, about 190 supernova νˉe+pe++n\bar{\nu}_e + p \to e^+ + n events would be detected. By adding MiniBooNE to the international network of supernova detectors, the possibility of a supernova being missed would be reduced. Additionally, the paths of the supernova neutrinos through Earth will be different for MiniBooNE and other detectors, thus allowing tests of matter-affected mixing effects on the neutrino signal.Comment: Added references, version to appear in PR

    Mitochondrial uncoupling links lipid catabolism to Akt inhibition and resistance to tumorigenesis

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    To support growth, tumour cells reprogramme their metabolism to simultaneously upregulate macromolecular biosynthesis while maintaining energy production. Uncoupling proteins (UCPs) oppose this phenotype by inducing futile mitochondrial respiration that is uncoupled from ATP synthesis, resulting in nutrient wasting. Here using a UCP3 transgene targeted to the basal epidermis, we show that forced mitochondrial uncoupling inhibits skin carcinogenesis by blocking Akt activation. Similarly, Akt activation is markedly inhibited in UCP3 overexpressing primary human keratinocytes. Mechanistic studies reveal that uncoupling increases fatty acid oxidation and membrane phospholipid catabolism, and impairs recruitment of Akt to the plasma membrane. Overexpression of Akt overcomes metabolic regulation by UCP3, rescuing carcinogenesis. These findings demonstrate that mitochondrial uncoupling is an effective strategy to limit proliferation and tumorigenesis through inhibition of Akt, and illuminate a novel mechanism of crosstalk between mitochondrial metabolism and growth signalling

    Experimental limits on nucleon decay and ΔB=2 processes

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    Results from the IMB collabration to detect possible proton decay in a salt mine near Cleveland, Ohio are presented. Detection apparatus is described.(AIP)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87900/2/1_1.pd

    Ernst Freund as Precursor of the Rational Study of Corporate Law

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    Gindis, David, Ernst Freund as Precursor of the Rational Study of Corporate Law (October 27, 2017). Journal of Institutional Economics, Forthcoming. Available at SSRN: https://ssrn.com/abstract=2905547, doi: https://dx.doi.org/10.2139/ssrn.2905547The rise of large business corporations in the late 19th century compelled many American observers to admit that the nature of the corporation had yet to be understood. Published in this context, Ernst Freund's little-known The Legal Nature of Corporations (1897) was an original attempt to come to terms with a new legal and economic reality. But it can also be described, to paraphrase Oliver Wendell Holmes, as the earliest example of the rational study of corporate law. The paper shows that Freund had the intuitions of an institutional economist, and engaged in what today would be called comparative institutional analysis. Remarkably, his argument that the corporate form secures property against insider defection and against outsiders anticipated recent work on entity shielding and capital lock-in, and can be read as an early contribution to what today would be called the theory of the firm.Peer reviewe

    The search for proton decay

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    Following a very brief description of the theoretical developments which motivated the search for proton decay, I shall describe one of these experiments (the IMB experiment) in some detail. Then I shall compare recent results from that experiment with those from other detectors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87399/2/321_1.pd

    Corporate governance and inequality: The impact of financialization and shareholder value

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    Copyright © 2017 by Emerald Group Publishing Limited. Purpose - The purpose of this chapter is to analyse how in recent years the rediscovery that extreme inequality is returning to advanced economies and has become widespread. What is at issue are the causes of this inequality. It is becoming clear that the wider population, particularly in Anglo-American economies have not shared in the growing wealth of the countries concerned, and that the majority of this wealth is being transferred on a continuous and systemic basis to the very rich. Corporate governance and the pursuit of shareholder value it is argued has become a major driver of inequality. Methodology/approach - The current statistical evidence produced by leading authorities including the US Federal Reserve, World Economic Forum, Credit Suisse and Oxfam are examined. The policy of shareholder value and the mechanisms by which the distributions from business take place are investigated from a critical perspective. Findings - While the Anglo-American economies are seeing a return to the extremes of inequality last witnessed in the 19th century, the causes of this inequality are changing. In the 19th century great fortunes often were inherited, or derived by entrepreneurs from the ownership and control of productive assets. By the late 20th century as Atkinson, Piketty and Saez (2011) and others have highlighted, the sustained and rapid inflation in top income shares have made a significant contribution to the accelerating rate of income and wealth inequality. Research implications - The intensification of inequality in advanced industrial economies, despite the consistent work of Atkinson and others, was largely neglected until the recent research of Picketty which has attracted international attention. It is now acknowledged widely that inequality is a serious issue; however, the contemporary causes of inequality remain largely unexplored. Practical/social implications - The significance of inequality, now that it is recognized, demands policy and practical interventions. However, the capacity or even willingness to intervene is lacking. Further analysis of the debilitating consequences of inequality in terms of the efficiency and stability of economies and societies may encourage a more robust approach, yet the resolve to end extreme inequality is not present. Originality/value - The analysis of inequality has not been neglected and this chapter represents a pioneering effort to relate the shareholder value orientation now dominant in corporate governance to the intensification of inequality
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