881 resultados para Electronically inelastic


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The (16)O+(27)Al elastic and inelastic angular distributions have been measured in a broad angular range (13 degrees < theta(lab) < 52 degrees) at about 100 MeV incident energy. The use of the MAGNEX large acceptance magnetic spectrometer and of the ray-reconstruction analysis technique has been crucial in order to provide, in the same experiment, high-resolution energy spectra and cross-section measurements distributed over more than seven orders of magnitude down to hundreds of nb/sr. (C) 2011 Elsevier B.V. All rights reserved.

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The provenance of entities, whether electronic data or physical artefacts, is crucial information in practically all domains, including science, business and art. The increased use of software in automating activities provides the opportunity to add greatly to the amount we can know about an entityâ??s history and the process by which it came to be as it is. However, it also presents difficulties: querying for the provenance of an entity could potentially return detailed information stretching back to the beginning of time, and most of it possibly irrelevant to the querier. In this paper, we define the concept of provenance query and describe techniques that allow us to perform scoped provenance queries.

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This study presents a qualitative evaluation of the Video and Audio Taped Evidence (VATE) process involving vulnerable witnesses, introduced by Victoria Police in 1996. Specifically, this study presents an analysis of individual in-depth interviews with a diverse group of 25 key Victorian stakeholders (police officers, prosecutors, solicitors, defence lawyers, and members of the judiciary). The aim of the interviews was to provide an overview of the stakeholders' perceptions of the VATE system, with particular focus on the usefulness of VATE interviews viewed or used in the stakeholders' practice. The findings revealed unanimous support for electronic recording of witness statements. However, the stakeholders also perceived that the effectiveness of the system was impeded by several factors. These include: (a) frequent absence within the interviews of a coherent account and detail needed to prove the various offences, (b) inability to scrutinise questions asked prior to the VATE interview, (c) lack of feedback regarding how well the VATE system is working, and (d) the recording medium itself which produced statements of poor sound and visual quality. Three broad recommendations arising from the interviews are discussed.

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Citizen participation, enabled by electronic means, grows, in parallel with government's apparent failure to promote it. Organisations such as Getup and Moveon flourish; the BBC announced in 2003 that 'Internet-based political activism is happening...The BBC wants to help a wider audience find their voice by tackling obstacles to greater participation' (http://www.opendemocracy.net). (Kevill, 2003). Such actions echo, perhaps, the enthusiastic adoption of the Internet by activist media groups, particularly Indymedia. This paper presents a response to this situation. It provides a richer account of the contradictory rise of e-government without e-governance, and examines the potential for media-based participatory engagement to complement e-government. It presents two models of the future of electronically mediated citizen engagement: the first involving agonistic relations between government and citizenry, with civic participation occurring outside of government-approved forums; the second involving the intimate linking of governmental transactions to participation by those citizens engaged in them. Finally it will outline mechanisms for researching the capacity of either or both models to sustain effective participation.

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The H1 Collaboration recently reported a new analysis of data on the inelastic photoproduction of J/psi mesons at DESY's HERA ep collider. We show that these new experimental results are well described by the color evaporation model for quarkonium production. Moreover, these new data require the introduction of resolved photon contributions in order to accommodate the results in the kinematic region where the fractional energy carried by the J/psi is small, demonstrating that colored perturbative c (c) over bar states contribute to the production of a color singlet.

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Scattering of positronium (Ps) by a helium atom has been investigated in a three-Ps-state coupled-channel model including Ps(1s,2s,2p) states using a recently proposed time-reversal-symmetric regularized electron-exchange model potential. Specifically, we report results of differential cross sections for elastic scattering and target-elastic Ps excitations. We also present results for total and different partial cross sections and compare them with experiment and other calculations.

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Elastic and inelastic positron-helium scattering have been investigated in different partial waves at medium energies using the close-coupling approximation with realistic wavefunctions employing the following states: He(1s1s), He(1s2s), He(1s2p), He(1s3s), He(1s3p), Ps(1s), Ps(2s) and Ps(2p). All excitations of the helium atom are in the spin-singlet electronic state. Calculations are reported of cross sections to He(1s1s), He(1s2s), and He(1s2p) transitions for incident positron energies up to 200 eV. These cross sections are in good agreement with experimental results.

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The phenomenon of Fermi acceleration is addressed for a dissipative bouncing ball model with external stochastic perturbation. It is shown that the introduction of energy dissipation (inelastic collisions of the particle with the moving wall) is a sufficient condition to break down the process of Fermi acceleration. The phase transition from bounded to unbounded energy growth in the limit of vanishing dissipation is characterized.

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Some dynamical properties of a classical particle confined inside a closed region with an oval-shaped boundary are studied. We have considered both the static and time-dependent boundaries. For the static case, the condition that destroys the invariant spanning curves in the phase space was obtained. For the time-dependent perturbation, two situations were considered: (i) non-dissipative and (ii) dissipative. For the non-dissipative case, our results show that Fermi acceleration is observed. When dissipation, via inelastic collisions, is introduced Fermi acceleration is suppressed. The behaviour of the average velocity for both the dissipative as well as the non-dissipative dynamics is described using the scaling approach. (C) 2009 Elsevier B.V. All rights reserved.

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Measurements of the inelastic photoproduction of charmonium at HERA have ignited a new charmonium crisis. The Color Singlet approach to computing onium production cross sections fits the data for large charmonium energy fraction z, where color octet models fail. This approach is however in qualitative disagreement with a wealth of information that exist on charmonium production by other initial states. We here suggest that the source of the discrepancy between color octet models (whether implemented in the soft color or NRQCD formalism) and data is due to the neglect of non-perturbative effects. Implementing these in a scheme originally developed for Drell-Yan phenomenology, we illustrate how agreement with the data is achieved. © 1999 Elsevier Science B.V. All rights reserved.

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The conditions for the existence of autosolitons were considered in trapped Bose-Einstein condensates with attractive atomic interactions. The expression for the parameters of the autosoliton was derived using the time-dependent variational approach for the nonconservative 3-dimensional Gross-pitaevskii equation and their stability was checked. The results were in agreement with the exact numerical calculations. It was shown that the transition from unstable to stable point solely depends on the magnitude of the parameters.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)