752 research outputs found

    Ageing in disordered magnets and local scale-invariance

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    The ageing of the bond-disordered two-dimensional Ising model quenched to below its critical point is studied through the two-time autocorrelator and thermoremanent magnetization (TRM). The corresponding ageing exponents are determined. The form of the scaling function of the TRM is well described by the theory of local scale-invariance.Comment: Latex2e, with epl macros, 7 pages, final for

    Kinetics of the long-range spherical model

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    The kinetic spherical model with long-range interactions is studied after a quench to T<TcT < T_c or to T=TcT = T_c. For the two-time response and correlation functions of the order-parameter as well as for composite fields such as the energy density, the ageing exponents and the corresponding scaling functions are derived. The results are compared to the predictions which follow from local scale-invariance.Comment: added "fluctuation-dissipation ratios"; fixed typo

    Ageing in bosonic particle-reaction models with long-range transport

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    Ageing in systems without detailed balance is studied in bosonic contact and pair-contact processes with Levy diffusion. In the ageing regime, the dynamical scaling of the two-time correlation function and two-time response function is found and analysed. Exact results for non-equilibrium exponents and scaling functions are derived. The behaviour of the fluctuation-dissipation ratio is analysed. A passage time from the quasi-stationary regime to the ageing regime is defined, in qualitative agreement with kinetic spherical models and p-spin spherical glasses.Comment: Latex2e, 24 pages, with 9 figures include

    Ageing, dynamical scaling and its extensions in many-particle systems without detailed balance

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    Recent studies on the phenomenology of ageing in certain many-particle systems which are at a critical point of their non-equilibrium steady-states, are reviewed. Examples include the contact process, the parity-conserving branching-annihilating random walk, two exactly solvable particle-reaction models and kinetic growth models. While the generic scaling descriptions known from magnetic system can be taken over, some of the scaling relations between the ageing exponents are no longer valid. In particular, there is no obvious generalization of the universal limit fluctuation-dissipation ratio. The form of the scaling function of the two-time response function is compared with the prediction of the theory of local scale-invariance.Comment: Latex2e with IOP macros, 32 pages; extended discussion on contact process and new section on kinetic growth processe

    Neutron Correlations in the Decay of the First Excited State of 11Li

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    The decay of unbound excited 11Li was measured after being populated by a two-proton removal from a 13B beam at 71 MeV/nucleon. Decay energy spectra and Jacobi plots were obtained from measurements of the momentum vectors of the 9Li fragment and neutrons. A resonance at an excitation energy of ∼1.2 MeV was observed. The kinematics of the decay are equally well fit by a simple dineutron-like model or a phase-space model that includes final state interactions. A sequential decay model can be excluded

    Cover Story: A Modus Vivendi? Sex, Marriage and the Church

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    The article presents divergent views on an analysis by historian Eamon Duffy of the Catholic Church\u27s response to shifting attitude towards sex and marriage in the West. Duffy noted that the church is increasingly confronted with the need to evolve a modus vivendi with social trends. Many Catholics are said to have disregarded the church\u27s teachings on sex and marriage. Other topics tackled include the increasing rate of divorce, premarital sex, same-sex unions and sexual education

    A Modus Vivendi? Sex, Marriage & the Church

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    During the 1960s, nearly 80 percent of adult Americans were married. A recent analysis of U.S. census data reported that only 52 percent of adult Americans were married in 2009. That is the lowest percentage reported in the 100 years the Census Bureau has collected such information. The reasons for this dramatic cultural shift are well known: high rates of divorce; changing attitudes toward premarital sex; social acceptability of cohabitation; the weakening of the stigma surrounding out-of-wedlock births and single parenting; the postponement of marriage and children for academic or professional reasons. Among those with only a high-school education or less, the data suggest that the decision to marry has been made more difficult by deteriorating economic conditions

    First Observation of Be-15

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    The neutron-unbound nucleus Be-15 was observed for the first time. It was populated using neutron transfer from a deuterated polyethylene target with a 59 MeV/u Be-14 beam. Neutrons were measured in coincidence with outgoing Be-14 particles and the reconstructed decay energy spectrum exhibits a resonance at 1.8(1) MeV. This corresponds to Be-15 being unbound by 0.45 MeV more then Be-16 thus significantly hindering the sequential two-neutron decay of Be-16 to Be-14 through this state
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