241,366 research outputs found

    An equation for the description of volume and temperature dependences of the dynamics of supercooled liquids and polymer melts

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    A recently proposed expression to describe the temperature and volume dependences of the structural (or alpha) relaxation time is discussed. This equation satisfies the scaling law for the relaxation times, tau = f(TV^g), where T is temperature, V the specific volume, and g a material-dependent constant. The expression for the function f is shown to accurately fit experimental data for several glass-forming liquids and polymers over an extended range encompassing the dynamic crossover, providing a description of the dynamics with a minimal number of parameters. The results herein can be reconciled with previously found correlations of the isochoric fragility with both the isobaric fragility at atmospheric pressure and the scaling exponent g.Comment: to be published in the special edition of J. Non-Crystalline Solids honoring K.L. Nga

    Semantic constraints on case assignment in secondary adjectival predicates in russian

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    Adjectival secondary predicates can enter into two Case frames in Russian, the agreeing form and the Instrumental. The paper argues that these Case frames go together with two syntactic positions in the clause which are correlated with two different interpretations, the true depictive and the temporally restricted reading, respectively. The availability of the two readings depends on the houndedness of the secondary predicate. Only bounded predicates can enter into both Case frames and only partially non-bounded predicates can appear in the Instrumental. The paper therefore argues that the pertinent two-way SL/IL-contrast is to he replaced by a three-way distinction in terms of boundedness. The paper outlines the syntax and semantics of the true depictive and the temporally restricted interpretation and discusses how adjectival secondary predicates whose salient properties involve a cotemporary interpretation with the matrix predicate and a control relation of an individual argument, differ from temporal adjuncts as well as from non-finite clauses

    Anaphor resolution and the scope of syntactic constraints

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    An anaphor resolution algorithm is presented which relies on a combination of strategies for narrowing down and selecting from antecedent sets for re exive pronouns, nonre exive pronouns, and common nouns. The work focuses on syntactic restrictions which are derived from Chomsky's Binding Theory. It is discussed how these constraints can be incorporated adequately in an anaphor resolution algorithm. Moreover, by showing that pragmatic inferences may be necessary, the limits of syntactic restrictions are elucidated

    The volatility of capital flows to emerging markets and financial services trade

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    This paper examines empirically the question whether the presence of foreign banks and a liberal trade regime with regard to financial services can contribute to a stabilization of capital flows to emerging markets. Since foreign banks, so the argument goes, provide better information to foreign investors and increase transparency, the danger of herding is reduced. Previous findings by Kono and Schuknecht (1998) confirmed empirically that such an effect does exist. This study expands their data set with respect to the length of the time period and the number of countries. Contrary to Kono and Schuknecht, it is found that foreign bank penetration tends to rather increase the volatility of capital flows. The trade regime variables are not significant in explaining cross-country variations in the volatility of capital flows. This result does not change significantly when alternative measures of volatility are considered. This paper was presented at the conference ''Financial crisis in transition countries: recent lessons and problems yet to solve'' on 13-14 July 2000 at the Institute for Economic Research (IWH) in Halle, Germany

    Gamma-ray line measurements from supernova explosions

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    Gamma ray lines are expected to be emitted as part of the afterglow of supernova explosions, because radioactive decay of freshly synthesised nuclei occurs. Significant radioactive gamma ray line emission is expected from 56Ni and 44Ti decay on time scales of the initial explosion (56Ni, tau~days) and the young supernova remnant (44Ti,tau~90 years). Less specific, and rather informative for the supernova population as a whole, are lessons from longer lived isotopes such as 26Al and 60Fe. From isotopes of elements heavier than iron group elements, any interesting gamma-ray line emission is too faint to be observable. Measurements with space-based gamma-ray telescopes have obtained interesting gamma ray line emissions from two core collapse events, Cas A and SN1987A, and one thermonuclear event, SN2014J. We discuss INTEGRAL data from all above isotopes, including all line and continuum signatures from these two objects, and the surveys for more supernovae, that have been performed by gamma ray spectrometry. Our objective here is to illustrate what can be learned from gamma-ray line emission properties about the explosions and their astrophysics.Comment: 7 pages, 4 figures. IAU Symposium 331 "SN1987A 30 years after", La Reunion, Feb. 2017. Accepted for publication in IAU Conf Pro

    Minimal zeros of copositive matrices

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    Let AA be an element of the copositive cone Cn{\cal C}_n. A zero uu of AA is a nonzero nonnegative vector such that uTAu=0u^TAu = 0. The support of uu is the index set \mbox{supp}u \subset \{1,\dots,n\} corresponding to the positive entries of uu. A zero uu of AA is called minimal if there does not exist another zero vv of AA such that its support \mbox{supp}v is a strict subset of \mbox{supp}u. We investigate the properties of minimal zeros of copositive matrices and their supports. Special attention is devoted to copositive matrices which are irreducible with respect to the cone S+(n)S_+(n) of positive semi-definite matrices, i.e., matrices which cannot be written as a sum of a copositive and a nonzero positive semi-definite matrix. We give a necessary and sufficient condition for irreducibility of a matrix AA with respect to S+(n)S_+(n) in terms of its minimal zeros. A similar condition is given for the irreducibility with respect to the cone Nn{\cal N}_n of entry-wise nonnegative matrices. For n=5n = 5 matrices which are irreducible with respect to both S+(5)S_+(5) and N5{\cal N}_5 are extremal. For n=6n = 6 a list of candidate combinations of supports of minimal zeros which an exceptional extremal matrix can have is provided.Comment: Some conditions and proofs simplifie
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