26,137 research outputs found
Coefficients and terms of the liquid drop model and mass formula
The coefficients of different combinations of terms of the liquid drop model
have been determined by a least square fitting procedure to the experimental
atomic masses. The nuclear masses can also be reproduced using a Coulomb radius
taking into account the increase of the ratio with increasing
mass, the fitted surface energy coefficient remaining around 18 MeV
Dilution jet mixing program, phase 3
The objectives of the program were: (1) to extend the data base on mixing of a single-sided row of jets with a confined crossflow, (2) to collect a data base on mixing of multiple rows of jets with confined crossflow, (3) to develop empirical jet mixing correlations, and (4) to perform limited three-dimensional calculations for some of these test configurations. The tests were performed with uniform mainstream conditions for several orifice plate configurations. Schematics of the test section and the orifice configurations are given. Temperature and pressure measurements were made in the test section at 4 axial and 11 transverse stations, using a 60-element rake probe. The measured temperature distributions for these tests are reported
PNJL model for adjoint fermions
Recent work on QCD-like theories has shown that the addition of adjoint
fermions obeying periodic boundary conditions to gauge theories on R^3 X S^1
can lead to a restoration of center symmetry and confinement for sufficiently
small circumference L of S^1. At small L, perturbation theory may be used
reliably to compute the effective potential for the Polyakov loop P in the
compact direction. Periodic adjoint fermions act in opposition to the gauge
fields, which by themselves would lead to a deconfined phase at small L. In
order for the fermionic effects to dominate gauge field effects in the
effective potential, the fermion mass must be sufficiently small. This
indicates that chiral symmetry breaking effects are potentially important. We
develop a Polyakov-Nambu-Jona Lasinio (PNJL) model which combines the known
perturbative behavior of adjoint QCD models at small L with chiral symmetry
breaking effects to produce an effective potential for the Polyakov loop P and
the chiral order parameter psi-bar psi. A rich phase structure emerges from the
effective potential. Our results are consistent with the recent lattice
simulations of Cossu and D'Elia, which found no evidence for a direct
connection between the small-L and large-L confining regions. Nevertheless, the
two confined regions are connected indirectly if an extended field theory model
with an irrelevant four-fermion interaction is considered. Thus the small-L and
large-L regions are part of a single confined phase.Comment: 6 pages, 4 figures; presented at INPC 201
Dilution jet mixing program, phase 3
The main objectives for the NASA Jet Mixing Phase 3 program were: extension of the data base on the mixing of single sided rows of jets in a confined cross flow to discrete slots, including streamlined, bluff, and angled injections; quantification of the effects of geometrical and flow parameters on penetration and mixing of multiple rows of jets into a confined flow; investigation of in-line, staggered, and dissimilar hole configurations; and development of empirical correlations for predicting temperature distributions for discrete slots and multiple rows of dilution holes
Black Holes with a Generalized Gravitational Action
Microscopic black holes are sensitive to higher dimension operators in the
gravitational action. We compute the influence of these operators on the
Schwarzschild solution using perturbation theory. All (time reversal invariant)
operators of dimension six are included (dimension four operators don't alter
the Schwarzschild solution). Corrections to the relation between the Hawking
temperature and the black hole mass are found. The entropy is calculated using
the Gibbons-Hawking prescription for the Euclidean path integral and using
naive thermodynamic reasoning. These two methods agree, however, the entropy is
not equal to 1/4 the area of the horizon.Comment: plain tex(uses phyzzx.tex), 8 pages, CALT-68-185
Lunar contour mapping system /lucom/ final report, 5 aug. 1964 - 18 mar. 1965
Radar sensor system for acquisition of lunar surface data - Lunar contour mapping syste
Liquid-Drop Model and Quantum Resistance Against Noncompact Nuclear Geometries
The importance of quantum effects for exotic nuclear shapes is demonstrated.
Based on the example of a sheet of nuclear matter of infinite lateral
dimensions but finite thickness, it is shown that the quantization of states in
momentum space, resulting from the confinement of the nucleonic motion in the
conjugate geometrical space, generates a strong resistance against such a
confinement and generates restoring forces driving the system towards compact
geometries. In the liquid-drop model, these quantum effects are implicitly
included in the surface energy term, via a choice of interaction parameters, an
approximation that has been found valid for compact shapes, but has not yet
been scrutinized for exotic shapes.Comment: 9 pages with 3 figure
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Enhancing engagement in evidence-based tobacco cessation treatment for smokers with mental illness: A pilot randomized trial.
ObjectiveTo evaluate the efficacy of a brief telephone-delivered Motivational Interviewing (MI)-based intervention to facilitate engagement in evidence-based cessation treatment for Veterans with mental illness referred to smoking cessation treatment.Methods86 military Veteran smokers with mental illness were recruited from a tobacco cessation consult clinic and randomized to receive either a MI-based treatment engagement intervention (TE; n = 48) or a non-MI assessment and information control (CON; n = 38) condition. Intervention was delivered during a single brief telephone contact. Primary engagement outcomes were 1) attending a treatment session within 30 days and 2) combination treatment (attending session plus using pharmacotherapy). Cessation outcomes included self-reported 24 h cessation attempts and 7 day point abstinence at 3 months post-intervention. Outcomes were assessed at 1 and 3 months post intervention.ResultsOutcome analyses included 85 participants (47 TE, 38 CON) using an intent-to-treat analytic approach. Participants were on average 49.5 (13.4) years old, 88% Male, 59% white, 18% African American and 14% Hispanic/Latino(a). Following intervention delivery TE and CON participants did not differ on likelihood of attending a treatment session during the subsequent 30 days (47% vs 45%, respectively). A significant difference was observed when classified as utilizing combination treatment, 40% of TE versus 18% of CON reported use of smoking cessation medication and behavioral counseling (p = 0.04). No statistical differences were observed for cessation outcomes, although more TE than CON participants reported 7 day point abstinence at 3 months post-intervention (30% vs 18%).ConclusionsThe present pilot study provides initial evidence for the feasibility, acceptability and efficacy of a telephone delivered TE intervention for enhancing engagement in combinationevidence evidence-based treatment in a sample of Veteran smokers with mental illness referred to smoking cessation treatment. Smokers with mental illness typically have greater difficulty stopping smoking than those without mental illness. Increased engagement in combination treatment thus has the potential to increase quit rates and ultimately reduce the burden of tobacco use for this population
Two-dimensional dilaton black holes
The two-dimensional CGHS model provides an interesting toy-model for the study of black hole evaporation. For this model, a quantum effective action, which incorporates Hawking radiation and backreaction, can be explicitly constructed. In this paper, we study a generalization of this effective action. In our extended model, it is possible to remove certain curvature singularities arising for the original theory. We also find that the flux of Hawking radiation is identical to that encountered in other two-dimensional models
Enhancing the work of the Islington Integrated Gangs Team: A pilot study on the response to serious youth violence in Islington
This report is the result of research conducted by the Centre for City Criminology at City, University of London, in partnership with Islington’s Integrated Gangs Team (IGT) and the Metropolitan Police Service (MPS). The research was co-funded by MPS and the School of Arts and Social Sciences, City, University of London. Following a collaborative research event in October 2017, City Criminologists were commissioned to carry out a small-scale research project to capture the work of the IGT and to make recommendations regarding its operations, coherence, effectiveness and sustainability. The research team conducted semi-structured interviews over several months with 23 practitioners across the services that constitute the IGT. This report presents the findings and recommendations
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