189 research outputs found
Interoperability and information sharing
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
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
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
- 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
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
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 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 photoproduction on a nucleon is discussed. We evaluate
the elastic 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 production from ,
and 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
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 and 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 in a
hypernucleus. Effects of the Pauli blocking at the quark level, particularly in
the open, coupled, 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
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
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 -Hyperon from pa Collision at Momentum of 10 Gev/
he observed well-known resonances (1385) and
(892) from PDG are good tests of this method. Exotic strange
multibaryon states have been observed in the effective mass spectra of:
,, , subsystems.
The mean value of mass for resonance is shifted till mass
of 1370 MeV/ and width is two times larger than the same value from PDG.
Such kind of behavior for width and invariant mass of
resonance is interpreted as extensive contribution from stopped
and medium effect with invariant mass. The mean value of
mass for from secondary interactions is also shifted till
mass of 1370 MeV/. The width of is 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
- …