665 research outputs found

    Isospin fractionation : equilibrium versus spinodal decomposition

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    This paper focuses on the isospin properties of the asymmetric nuclear-matter liquid-gas phase transition analyzed in a mean-field approach, using Skyrme effective interactions. We compare two different mechanisms of phase separation for low-density matter: equilibrium and spinodal decomposition. The isospin properties of the phases are deduced from the free-energy curvature, which contains information both on the average isospin content and on the system fluctuations. Some implications on experimentally accessible isospin observables are presented

    The role of contacts in graphene transistors: A scanning photocurrent study

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    A near-field scanning optical microscope is used to locally induce photocurrent in a graphene transistor with high spatial resolution. By analyzing the spatially resolved photo-response, we find that in the n-type conduction regime a p-n-p structure forms along the graphene device due to the doping of the graphene by the metal contacts. The modification of the electronic structure is not limited only underneath the metal electrodes, but extends 0.2-0.3 um into the graphene channel. The asymmetric conduction behavior of electrons and holes that is commonly observed in graphene transistors is discussed in light of the potential profiles obtained from this photocurrent imaging approach. Furthermore, we show that photocurrent imaging can be used to probe single- / multi-layer graphene interfaces

    Influence of the Coulomb Interaction on the Chemical Equilibrium of Nuclear Systems at Break-Up

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    The importance of a Coulomb correction to the formalism proposed by Albergo et al. for determining the temperatures of nuclear systems at break-up and the ensities of free nucleon gases is discussed. While the proposed correction has no effect on the temperatures extracted based on double isotope ratios, it becomes non-negligible when such temperatures or densities of free nucleon gases are extracted based on multiplicities of heavier fragments of different atomic numbers

    Probing the nuclear EOS with fragment production

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    We discuss fragmentation mechanisms and isospin transport occurring in central collisions between neutron rich systems at Fermi energies. In particular, isospin effects are analyzed looking at the correlations between fragment isotopic content and kinematical properties. Simulations are based on an approximate solution of the Boltzmann-Langevin (BL) equation. An attempt to solve the complete BL equation, by introducing full fluctuations in phase space is also discussed.Comment: 10 pages, 4 figures; Int.Nucl.Phys.Conf., Tokyo June 07, to appear in Nucl.Phys.A (Elsart

    Validation of the disease-specific components of the Kidney Disease Quality of Life-36 (KDQOL-36) in Chinese patients undergoing maintenance dialysis

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    AIM: The aim of this study was to evaluate the validity, reliability and sensitivity of the disease-specific items of the Kidney Disease Quality of Life-36 (KDQOL-36) in Chinese patients undergoing maintenance dialysis. METHODS: The content validity was assessed by content validity index (CVI) in ten subjects. 356 subjects were recruited for pilot psychometric testing. The internal construct validity was assessed by corrected item-subscale total correlation. Confirmatory factor analysis (CFA) was used to confirm the factor structure. The convergent validity was assessed by Pearson's correlation test between the disease specific subscale scores and SF-12 version 2 Health Survey (SF-12 v2) scores. The reliability was assessed by the internal consistency (Cronbach's Alpha coefficient) and 2-week test-retest reliability (intraclass correlation coefficient (ICC)). The sensitivity was determined by performing known group comparisons by independent t-test. RESULTS: The CVI on clarity and relevance was â ¥ 0.9 for all items. Corrected item- total correlation scores were â ¥0.4 for all, except an item related to problems with access site. CFA confirmed the 3-factor structure of the disease-specific component of the KDQOL-36. The correlation coefficients between the disease-specific domain scores and the SF-12 v2 physical and mental component summary scores ranged from 0.328 to 0.492. The reliability was good (Cronbach's alpha coefficients ranged from 0.810 to 0.931, ICC ranged from 0.792 to 0.924). Only the effect subscale was sensitive in detecting differences in HRQOL between haemodialysis and peritoneal dialysis patients, with effect size = 0.68. CONCLUSION: The disease-specific items of the KDQOL-36 are a valid, reliable and sensitive measure to assess the health-related quality of life of Chinese patients on maintenance dialysis.published_or_final_versio

    Model of multifragmentation, Equation of State and phase transition

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    We consider a soluble model of multifragmentation which is similar in spirit to many models which have been used to fit intermediate energy heavy ion collision data. We draw a p-V diagram for the model and compare with a p-V diagram obtained from a mean-field theory. We investigate the question of chemical instability in the multifragmentation model. Phase transitions in the model are discussed.Comment: Revtex, 9 pages including 6 figures: some change in the text and Fig.

    Dynamical approach to spectator fragmentation in Au+Au reactions at 35 MeV/A

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    The characteristics of fragment emission in peripheral 197^{197}Au+197^{197}Au collisions 35 MeV/A are studied using the two clusterization approaches within framework of \emph{quantum molecular dynamics} model. Our model calculations using \emph{minimum spanning tree} (MST) algorithm and advanced clusterization method namely \emph{simulated annealing clusterization algorithm} (SACA) showed that fragment structure can be realized at an earlier time when spectators contribute significantly toward the fragment production even at such a low incident energy. Comparison of model predictions with experimental data reveals that SACA method can nicely reproduce the fragment charge yields and mean charge of the heaviest fragment. This reflects suitability of SACA method over conventional clusterization techniques to investigate spectator matter fragmentation in low energy domain.Comment: 6 pages, 5 figures, accepte

    Size Matters: Origin of Binomial Scaling in Nuclear Fragmentation Experiments

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    The relationship between measured transverse energy, total charge recovered in the detector, and size of the emitting system is investigated. Using only very simple assumptions, we are able to reproduce the observed binomial emission probabilities and their dependences on the transverse energy.Comment: 14 pages, including 4 figure
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