189 research outputs found

    Interoperability and information sharing

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    Communication and information sharing are two of the most pressing issues facing the public safety community today. In previous chapters of this volume, authors have made note of the changing public safety landscape as it relates to the need for enhanced information and intelligence sharing among a broad cross-section of organizations. Public safety organizations, particularly law enforcement agencies, have been quick to adopt emerging technologies that have allowed for greater communication and information sharing capacities. While substantial improvements have been made over the decades that enhanced communication and information sharing, many challenges remain in the move to seamlessly integrated communication capacities. The key challenge in the upcoming decades relates to the technical and cultural changes necessary to achieve integrated communication systems. There is no shortage of resources given to increasing the communications capacity of the public safety community, yet serious challenges remain in the degree of interoperability within and across public safety domains. Interoperability has in many ways become the defining issue in the arenas of communications and information sharing. This chapter will provide an overview of critical historical events that placed questions of interoperability and information sharing on the national agenda. The chapter will also provide an overview of national models for information sharing

    Selective Photothermolysis of Cutaneous Pigmentation by Q-switched Nd: YAG Laser Pulses at 1064, 532. and 355nm

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    Exposure of skin to nanosecond-domain laser pulses affects the pigmentary system by a process called selective photothermolysis, in which melanosomes and pigmented cells are preferentially altered. Due to the broad absorption spectrum of melanin, this effect may occur with wavelengths that penetrate to vastly different depths within tissue, potentially producing different biologic responses. The effects of single near-ultraviolet (355nm), visible (532nm), and near infrared (1064nm) pulses of 10–12nsec duration were determined in guinea pig skin using gross, histologic, and electron microscopic observations. Threshold response in pigmented skin was a transient immediate ash-white discoloration, requiring 0.11, 0.20 and 1.0J/cm2, at 355, 532, and 1064 nm, respectively. At each wavelength, melanosomes were reputed within keratinocytes and melanocytes, with cytoplasmic and nuclear alterations. Delayed epidermal depigmentation occurred, followed by gradual repigmentation. Deep follicular cells were altered only at 532 and 1064 nm, which produced permanent leukotrichia. The action spectrum for threshold response was consistent with mechanisms implied by selective photothermolysis. These data may be useful for consideration of treatment for cutaneous pigmentation abnormalities or unwanted follicular pigmentation, or both

    Microscopic approach to pion-nucleus dynamics

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    Elastic scattering of pions from finite nuclei is investigated utilizing a contemporary, momentum--space first--order optical potential combined with microscopic estimates of second--order corrections. The calculation of the first--order potential includes:\ \ (1)~full Fermi--averaging integration including both the delta propagation and the intrinsic nonlocalities in the π\pi-NN amplitude, (2)~fully covariant kinematics, (3)~use of invariant amplitudes which do not contain kinematic singularities, and (4)~a finite--range off--shell pion--nucleon model which contains the nucleon pole term. The effect of the delta--nucleus interaction is included via the mean spectral--energy approximation. It is demonstrated that this produces a convergent perturbation theory in which the Pauli corrections (here treated as a second--order term) cancel remarkably against the pion true absorption terms. Parameter--free results, including the delta--nucleus shell--model potential, Pauli corrections, pion true absorption, and short--range correlations are presented. (2 figures available from authors)Comment: 13 page

    On the pion-nucleon coupling constant

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    In view of persisting misunderstanding about the determination of the pion-nucleon coupling constants in the Nijmegen multienergy partial-wave analyses of pp, np, and pbar-p scattering data, we present additional information which may clarify several points of discussion. We comment on several recent papers addressing the issue of the pion-nucleon coupling constant and criticizing the Nijmegen analyses.Comment: 19 pages, Nijmegen preprint THEF-NYM-92-0

    Charmonium absorption by nucleons

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    J/ΨJ/\Psi dissociation in collisions with nucleons is studied within a boson exchange model and the energy dependence of the dissociation cross section is calculated from the threshold for ΛcDˉ\Lambda_c{\bar D} production to high energies. We illustrate the agreement of our results with calculations based on short distance QCD and Regge theory. The compatibility between our calculations and the data on J/ΨJ/\Psi photoproduction on a nucleon is discussed. We evaluate the elastic J/Ψ+NJ/\Psi{+}N cross section using a forward dispersion relation and demonstrate the overall agreement with the predictions from QCD sum rules. Our results are compatible with the phenomenological dissociation cross section evaluated from the experimental data on J/ΨJ/\Psi production from γ+A\gamma{+}A, p+Ap{+}A and A+AA{+}A collisions.Comment: 14 pages, revtex, including 13 figures, accepted for publication in Phys. Rev.

    The quark-meson coupling model for Lambda, Sigma and Xi hypernuclei

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    The quark-meson coupling (QMC) model, which has been successfully used to describe the properties of both infinite nuclear matter and finite nuclei, is applied to a systematic study of Λ,Σ\Lambda, \Sigma and Ξ\Xi hypernuclei. Assumptions made in the present study are, (i) the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d quarks, and (ii) an SU(6) valence quark model for the bound nucleons and hyperon. The model automatically leads to a very weak spin-orbit interaction for the Λ\Lambda in a hypernucleus. Effects of the Pauli blocking at the quark level, particularly in the open, coupled, ΣNΛN\Sigma N - \Lambda N channel (strong conversion), is also taken into account in a phenomenological way.Comment: 27 pages, 14 postscript figures, uses epsfig.sty. Version to appear in Nucl. Phys.

    The Hubbard model within the equations of motion approach

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    The Hubbard model has a special role in Condensed Matter Theory as it is considered as the simplest Hamiltonian model one can write in order to describe anomalous physical properties of some class of real materials. Unfortunately, this model is not exactly solved except for some limits and therefore one should resort to analytical methods, like the Equations of Motion Approach, or to numerical techniques in order to attain a description of its relevant features in the whole range of physical parameters (interaction, filling and temperature). In this manuscript, the Composite Operator Method, which exploits the above mentioned analytical technique, is presented and systematically applied in order to get information about the behavior of all relevant properties of the model (local, thermodynamic, single- and two- particle ones) in comparison with many other analytical techniques, the above cited known limits and numerical simulations. Within this approach, the Hubbard model is shown to be also capable to describe some anomalous behaviors of the cuprate superconductors.Comment: 232 pages, more than 300 figures, more than 500 reference

    Near threshold enhancement of the ppbar mass spectrum in J/Psi decay

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    We investigate the nature of the near-threshold enhancement in the ppbar invariant mass spectrum of the reaction J/Psi -> gamma ppbar reported recently by the BES Collaboration. Using the Juelich NNbar model we show that the mass dependence of the ppbar spectrum close to the threshold can be reproduced by the S-wave ppbar final state interaction in the isospin I=1 state within the Watson-Migdal approach. However, because of our poor knowledge of the NNbar interaction near threshold and of the J/Psi -> gamma ppbar reaction mechanism and in view of the controversal situation in the decay J/Psi -> pi0 ppbar, where no obvious signs of a ppbar final state interaction are seen, explanations other than final state interactions cannot be ruled out at the present stage.Comment: 9 pages, 7 figure

    The Observed Correlations for the Strange Multibaryon States in Systems with Λ\Lambda-Hyperon from pa Collision at Momentum of 10 Gev/cc

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    he observed well-known resonances Σ0\Sigma^0 Σ+\Sigma^{*+}(1385) and K±K^{*\pm}(892) from PDG are good tests of this method. Exotic strange multibaryon states have been observed in the effective mass spectra of: Λπ±\Lambda \pi^{\pm},Λγ\Lambda \gamma, Λp\Lambda p, Λpp\Lambda p p subsystems. The mean value of mass for Σ(1385)\Sigma^{*-}(1385) resonance is shifted till mass of 1370 MeV/c2c^2 and width is two times larger than the same value from PDG. Such kind of behavior for width and invariant mass of Σ(1385)\Sigma^{*-}(1385) resonance is interpreted as extensive contribution from stopped ΞΛπ\Xi^-\to\Lambda\pi^- and medium effect with invariant mass. The mean value of mass for Σ+(1385)\Sigma^{*+}(1385) from secondary interactions is also shifted till mass of 1370 MeV/c2c^2. The width of Σ0\Sigma^0 is \approx 2 times larger than the experimental error. There are enhancement production for all observed hyperons.Comment: 4 pages, 6 figures, XXIst Rencontres de Blois "Windows on the Universe " Blois, France June 21st - June 26th, 200
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