2,263 research outputs found

    Assessing user preferences for eReaders and tablets

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    Journal ArticleLibrarians purchased twelve ereaders and six tablets to provide patrons the opportunity to experiment with the latest mobile technologies. After several train the trainer sessions, librarians shared device information with the broader health sciences community. Devices were cataloged and made available for two-week checkout. A limited number of books and apps were pre-loaded for all the devices and patrons were allowed to download their own content. Each tablet has Google Books, iBooks, Kindle, and Nook apps available to allow choice in reading ebooks. Upon return, patrons were asked to complete a ten question survey to determine preferences for device use

    Torsion bounds for a fixed abelian variety and varying number field

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    Let AA be an abelian variety defined over a number field KK. For a finite extension L/KL/K, the cardinality of the group A(L)tors⁥A(L)_{\operatorname{tors}} of torsion points in A(L)A(L) can be bounded in terms of the degree [L:K][L:K]. We study the smallest real number ÎČA\beta_A such that for any finite extension L/KL/K and Δ>0\varepsilon>0, we have ∣A(L)torsâĄâˆŁâ‰€C⋅[L:K]ÎČA+Δ|A(L)_{\operatorname{tors}}| \leq C \cdot [L:K]^{\beta_A+\varepsilon}, where the constant CC depends only on AA and Δ\varepsilon (and not LL). Assuming the Mumford-Tate conjecture for AA, we will show that ÎČA\beta_A agrees with the conjectured value of Hindry and Ratazzi.Comment: 29 pages, comments very welcome

    Alpha-particle clustering in excited expanding self-conjugate nuclei

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    The fragmentation of quasi-projectiles from the nuclear reaction 40Ca + 12C at 25 MeV/nucleon was used to produce alpha-emission sources. From a careful selection of these sources provided by a complete detection and from comparisons with models of sequential and simultaneous decays, strong indications in favour of α\alpha-particle clustering in excited 16O, 20Ne and 24}Mg are reported.Comment: 8 pages, 4 figures, 12th International Conference on Nucleus-Nucleus collisions (NN2015), 21-26 June 2015, Catania, Ital

    Pathologies of Quenched Lattice QCD at non--zero Density and its Effective Potential

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    We simulate lattice QCD at non--zero baryon density and zero temperature in the quenched approximation, both in the scaling region and in the infinite coupling limit. We investigate the nature of the forbidden region -- the range of chemical potential where the simulations grow prohibitively expensive, and the results, when available, are puzzling if not unphysical. At weak coupling we have explored the sensitivity of these pathologies to the lattice size, and found that using a large lattice (64×16364 \times 16^3) does not remove them. The effective potential sheds considerable light on the problems in the simulations, and gives a clear interpretation of the forbidden region. The strong coupling simulations were particularly illuminating on this point.Comment: 49 pages, uu-encoded expanding to postscript;also available at ftp://hlrz36.hlrz.kfa-juelich.de/pub/mpl/hlrz72_95.p

    Production of α\alpha-particle condensate states in heavy-ion collisions

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    The fragmentation of quasi-projectiles from the nuclear reaction 40Ca^{40}Ca + 12C^{12}C at 25 MeV/nucleon was used to produce excited states candidates to α\alpha-particle condensation. The experiment was performed at LNS-Catania using the CHIMERA multidetector. Accepting the emission simultaneity and equality among the α\alpha-particle kinetic energies as experimental criteria for deciding in favor of the condensate nature of an excited state, we analyze the 02+0_2^+ and 22+2_2^+ states of 12^{12}C and the 06+0_6^+ state of 16^{16}O. A sub-class of events corresponding to the direct 3-α\alpha decay of the Hoyle state is isolated.Comment: contribution to the 2nd Workshop on "State of the Art in Nuclear Cluster Physics" (SOTANCP2), Universite Libre de Bruxelles (Belgium), May 25-28, 2010, to be published in the International Journal of Modern Physics

    Coulomb chronometry to probe the decay mechanism of hot nuclei

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    In 129 Xe+ nat Sn central collisions from 8 to 25 MeV/A, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is determined. Strong Coulomb proximity effects are observed in the three-fragment final state. A comparison with Coulomb trajec-tory calculations shows that the time scale between the consecutive break-ups decreases with increasing bombarding energy, becoming quasi-simultaneous above excitation energy E * = 4.0±\pm0.5 MeV/A. This transition from sequential to simultaneous break-up was interpreted as the signature of the onset of multifragmentation for the three-fragment exit channel in this system.Comment: 12 pages; 13 Figures; 4 Table; Accepted for publication in Physical Review

    Static correlation lengths in QCD at high temperature and finite density

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    A brief review is given of the sign problem in finite density lattice QCD and various attempts to overcome it. To date there is still no solution to this problem which would work for realistic QCD. The main focus then is on the deconfined phase, where QCD can be described by a dimensionally reduced effective action. After summarizing derivation and validity of the effective theory, it is demonstrated that it can be simulated efficiently in the presence of a chemical potential for quarks \mu/T\lsim 4. Direct comparison of simulations with imaginary and real Ό\mu suggests that equilibrium plasma properties could be analytically continued from 4d QCD simulations at imaginary Ό\mu.Comment: Lattice 2000 (plenary), 12 pages, 9 figures, typos corrected, Fig.7 replaced by black and whit

    How particles emerge from decaying classical fields in heavy ion collisions: towards a kinetic description of the Glasma

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    We develop the formalism discussed previously in hep-ph/0601209 and hep-ph/0605246 to construct a kinetic theory that provides insight into the earliest ``Glasma'' stage of a high energy heavy ion collision. Particles produced from the decay of classical fields in the Glasma obey a Boltzmann equation whose novel features include an inhomogeneous source term and new contributions to the collision term. We discuss the power counting associated with the different terms in the Boltzmann equation and outline the transition from the field dominated regime to the particle dominated regime in high energy heavy ion collisions.Comment: 29 pages, 16 postscript figures, some typos correcte
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