6,739 research outputs found

    Uniform asymptotics of the coefficients of unitary moment polynomials

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    Keating and Snaith showed that the 2kth2k^{th} absolute moment of the characteristic polynomial of a random unitary matrix evaluated on the unit circle is given by a polynomial of degree k2k^2. In this article, uniform asymptotics for the coefficients of that polynomial are derived, and a maximal coefficient is located. Some of the asymptotics are given in explicit form. Numerical data to support these calculations are presented. Some apparent connections between random matrix theory and the Riemann zeta function are discussed.Comment: 31 pages, 1 figure, 2 tables. A few minor misprints fixe

    Random polynomials, random matrices, and LL-functions

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    We show that the Circular Orthogonal Ensemble of random matrices arises naturally from a family of random polynomials. This sheds light on the appearance of random matrix statistics in the zeros of the Riemann zeta-function.Comment: Added background material. Final version. To appear in Nonlinearit

    Chesapeake Bay Wave Climate : Wolf Trap Wave Station, Report and Summary of Wave Observations November 6, 1989 through August 2, 1990

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    The Virginia Institute of Marine Science, in cooperation with the Virginia Department of Conservation and Recreation, Division of Soil and Water Conservation, has identified as one of its major goals the systematic study of hydrodynamic processes that affect recreational, shoreline and benthic resources in the coastal zone of the Commonwealth. In pursuit of that goal, a long-term study of the wave climate in the Virginia portion of Chesapeake Bay was initiated in 1988 with support from the National Oceanographic and Atmospheric Administration through the Coastal Zone Management Program administered by the Virginia Council on the Environment (Grant No. NA89AA-D-CZ134)

    Chesapeake Bay wave climate : Thimble Shoal light wave station, report and summary of wave observations, October 8, 1990 through August 22, 1991 and Chesapeake light tower - VIMS Star gage test measurements and evaluation, July, August, October 1991

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    This report also presents a description of a directional wave gaging system, known as a Star gage, that is designed for long-term, low-maintenance operation both within and immediately outside the Chesapeake Bay entrance area. This development was prompted by our dependence to date on the single-point, PUV-type directional wave gage described below. While ideally suited for short-term investigative studies at different sites, the PUV directional wave gage requires field service visits at monthly intervals to maintain adequate performance and uninterrupted operation. A prototype Star gage system was constructed and field tested to evaluate its potential use as a long-term and eventual real-time wave gage for the Virginia coastal environment. A test deployment of the VIMS Star gage, a 4-element pressure sensor array utilizing a star configuration (Goda, 1985) was conducted at the Chesapeake Light Tower (CLT, Fig. 1) located approximately 14 nautical miles east of the bay entrance. Results of these tests are reported in Section VII

    Does the European Union have a reverse gear? Policy dismantling in a hyperconsensual polity

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    The financial crisis has triggered demands to halt and even reverse the expansion of European Union (EU) policies. But have these and previous demands actually resulted in policy dismantling? The existing literature has charted the rise of dismantling discourses such as subsidiarity and better regulation, but has not examined the net effect on the acquis. For the first time, this contribution addresses this gap in the literature through an empirical study of policy change between 1992 and 2014. It is guided by a coding framework which captures the direction of policy change. It reveals that, despite its disposition towards consensualism, the EU has become a new locus of policy dismantling. However, not all policies targeted have been cut; many have stayed the same and some have even expanded. It concludes by identifying new directions for research on a topic that has continually fallen into the analytical blind spot of EU scholars

    The production and persistence of ΣRONO2 in the Mexico City plume

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    Alkyl and multifunctional nitrates (RONO2, ΣANs) have been observed to be a significant fraction of NOy in a number of different chemical regimes. Their formation is an important free radical chain termination step ending production of ozone and possibly affecting formation of secondary organic aerosol. ΣANs also represent a potentially large, unmeasured contribution to OH reactivity and are a major pathway for the removal of nitrogen oxides from the atmosphere. Numerous studies have investigated the role of nitrate formation from biogenic compounds and in the remote atmosphere. Less attention has been paid to the role ΣANs may play in the complex mixtures of hydrocarbons typical of urban settings. Measurements of total alkyl and multifunctional nitrates, NO2, total peroxy nitrates (ΣPNs), HNO3 and a representative suite of hydrocarbons were obtained from the NASA DC-8 aircraft during spring of 2006 in and around Mexico City and the Gulf of Mexico. ΣANs were observed to be 10–20% of NOy in the Mexico City plume and to increase in importance with increased photochemical age. We describe three conclusions: (1) Correlations of ΣANs with odd-oxygen (Ox) indicate a stronger role for ΣANs in the photochemistry of Mexico City than is expected based on currently accepted photochemical mechanisms, (2) ΣAN formation suppresses peak ozone production rates by as much as 40% in the near-field of Mexico City and (3) ΣANs play a significant role in the export of NOy from Mexico City to the Gulf Region

    Cellular automaton rules conserving the number of active sites

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    This paper shows how to determine all the unidimensional two-state cellular automaton rules of a given number of inputs which conserve the number of active sites. These rules have to satisfy a necessary and sufficient condition. If the active sites are viewed as cells occupied by identical particles, these cellular automaton rules represent evolution operators of systems of identical interacting particles whose total number is conserved. Some of these rules, which allow motion in both directions, mimic ensembles of one-dimensional pseudo-random walkers. Numerical evidence indicates that the corresponding stochastic processes might be non-Gaussian.Comment: 14 pages, 5 figure

    Effects of Neutron Irradiation on Carbon Doped MgB2 Wire Segments

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    We have studied the evolution of superconducting and normal state properties of neutron irradiated Mg(B.962_{.962}C.038_{.038})2_2 wire segments as a function of post exposure annealing time and temperature. The initial fluence fully suppressed superconductivity and resulted in an anisotropic expansion of the unit cell. Superconductivity was restored by post-exposure annealing. The upper critical field, Hc2_{c2}(T=0), approximately scales with Tc_c starting with an undamaged Tc_c near 37 K and Hc2_{c2}(T=0) near 32 T. Up to an annealing temperature of 400 o^ oC the recovery of Tc_c tends to coincide with a decrease in the normal state resistivity and a systematic recovery of the lattice parameters. Above 400 o^ oC a decrease in order along the c- direction coincides with an increase in resistivity, but no apparent change in the evolution of Tc_c and Hc2_{c2}. To first order, it appears that carbon doping and neutron damaging effect the superconducting properties of MgB2_2 independently

    Returning children home from care: What can be learned from local authority data?

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    International Human Rights and child rights conventions as well as U.K. wide legislation and guidance require that children in care should be returned home to one or both parents wherever possible. Reunification with parents is the most common route out of care, but rates of re‐entry are often higher than for other exit routes. This study used 8 years of administrative data (on 2,208 care entrants), collected by one large English local authority, to examine how many children were returned home and to explore factors associated with stable reunification (not re‐entering care for at least 2 years). One‐third of children (36%) had been reunified, with adolescent entrants being the most likely age group to return home. Three quarters (75%) of reunified children had a stable reunification. In a fully adjusted regression model, age at entry, being on a care order prior to return home, staying longer in care, being of minority ethnicity, and having fewer placements in care were all significant in predicting chances of stable reunification. The results underline the importance of properly resourcing reunification services. The methods demonstrate the value to local authorities of analysing their own data longitudinally to understand the care pathways for children they look after
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