1,199 research outputs found

    Disegno geometrico e storia dell\u2019arte nell\u2019accademia di Pietro Selvatico (1849-1859)

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    This book chapter investigates Pietro Selvatico Estense's position as director of the Venice Academy of Fine Arts (1849-1859). During this period art history classes and linear drawing have been strengthened within the academic curriculum

    Nuclear binding energies: Global collective structure and local shell-model correlations

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    Nuclear binding energies and two-neutron separation energies are analyzed starting from the liquid-drop model and the nuclear shell model in order to describe the global trends of the above observables. We subsequently concentrate on the Interacting Boson Model (IBM) and discuss a new method in order to provide a consistent description of both, ground-state and excited-state properties. We address the artefacts that appear when crossing mid-shell using the IBM formulation and perform detailed numerical calculations for nuclei situated in the 50-82 shell. We also concentrate on local deviations from the above global trends in binding energy and two-neutron separation energies that appear in the neutron-deficient Pb region. We address possible effects on the binding energy, caused by mixing of low-lying 0+0^{+} intruder states into the ground state, using configuration mixing in the IBM framework. We also study ground-state properties using a deformed mean-field approach. Detailed comparisons with recent experimental data in the Pb region are amply discussed.Comment: 69 pages, TeX (ReVTeX). 23 eps figures. 1 table. Modified version. Accepted in Nucl. Phys.

    High temperature thermodynamics of fermionic alkaline earth atoms in optical lattices

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    We calculate experimentally relevant properties of trapped fermionic alkaline earth atoms in an optical lattice, modeled by the SU(N) Hubbard model. Our calculation is accurate when the temperature is much larger than the tunneling rate, similar to current regimes in ultracold atom experiments. In addition to exploring the Mott insulator-metal crossover, we calculate final temperatures achieved by the standard experimental protocol of adiabatically ramping from a non-interacting gas, as a function of initial gas temperature and final state lattice parameters. Of particular experimental interest, we find that increasing NN gives substantially \textit{colder} Mott insulators, up to more than a factor of five for relevant parameters. This cooling happens for all NN, fixing the initial entropy, or for all N \lsim 20 (the exact value depends on dimensionality), fixing the initial temperature.Comment: 4+ pages main text, 2 figures. 3 pages supplementary information, 2 figures. v2: added citatio

    Proton-neutron quadrupole interactions: an effective contribution to the pairing field

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    We point out that the proton-neutron energy contribution, for low multipoles (in particular for the quadrupole component), effectively renormalizes the strength of the pairing interaction acting amongst identical nucleons filling up a single-j or a set of degenerate many-j shells. We carry out the calculation in lowest-order perturbation theory. We perform a study of this correction in various mass regions. These results may have implications for the use of pairing theory in medium-heavy nuclei and for the study of pairing energy corrections to the liquid drop model when studying nuclear masses.Comment: 19 pages, TeX, 3 tables, 2 figures. Accepted in PR

    Modified Bethe-Weizsacker mass formula with isotonic shift and new driplines

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    Nuclear masses are calculated using the modified Bethe-Weizsacker mass formula in which the isotonic shifts have been incorporated. The results are compared with the improved liquid drop model with isotonic shift. Mass excesses predicted by this method compares well with the microscopic-macroscopic model while being much more simple. The neutron and proton drip lines have been predicted using this modified Bethe-Weizsacker mass formula with isotonic shifts.Comment: 9 pages including 2 figure

    A portable quartz micro balance for physical vapor deposition techniques

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    A portable quartz crystal micro balance for physical vapor deposition techniques is presented. The device is used for the calibration of evaporators employed in the preparation of thin film systems that are studied in surface science. The design is based upon a portable sample setup, highly versatile and customizable. It can be transported within an ultrahigh vacuum system, stored in a sample garage and be used in front of different evaporators. Details of the setup are described. Finally, the performance of the device is demonstrated and compared to scanning tunneling microscopy measurements

    The Multidimensional Study of Viral Campaigns as Branching Processes

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    Viral campaigns on the Internet may follow variety of models, depending on the content, incentives, personal attitudes of sender and recipient to the content and other factors. Due to the fact that the knowledge of the campaign specifics is essential for the campaign managers, researchers are constantly evaluating models and real-world data. The goal of this article is to present the new knowledge obtained from studying two viral campaigns that took place in a virtual world which followed the branching process. The results show that it is possible to reduce the time needed to estimate the model parameters of the campaign and, moreover, some important aspects of time-generations relationship are presented.Comment: In proceedings of the 4th International Conference on Social Informatics, SocInfo 201
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