1,092 research outputs found
UMIS & urban habilitation in Venezuela
The paper describes the Urban Management Information System (UMIS) designed to monitor
and evaluated the execution of the Actions and Investments Program (AIP) elaborate
with the actors implied in the urban HABILITATION of neighbourhoods, policy implemented
by the National Housing Counsel (CONAVI) in Venezuela. This Geographical Information
and Territorial Management System, permits the visualization and recognition
of the plan’s advance through the execution of the AIP and makes possible the application
of corrective actions to achieve a sustainable habitat, all of which impacts positively
the quality of life in poor neighbourhoods, the urban agents legitimacy and the local gobernability.Peer Reviewe
Relativistic analysis of the 208Pb(e,e'p)207Tl reaction at high momentum
The recent 208Pb(e,e'p)207Tl data from NIKHEF-K at high missing momentum
(p_m>300 MeV/c) are compared to theoretical results obtained with a fully
relativistic formalism previously applied to analyze data on the low missing
momentum (p_m < 300 MeV/c) region. The same relativistic optical potential and
mean field wave functions are used in the two p_m-regions. The spectroscopic
factors of the various shells are extracted from the analysis of the low-p_m
data and then used in the high-p_m region. In contrast to previous analyses
using a nonrelativistic mean field formalism, we do not find a substantial
deviation from the mean field predictions other than that of the spectroscopic
factors, which appear to be consistent with both low- and high-p_m data. We
find that the difference between results of relativistic and nonrelativistic
formalisms is enhanced in the p_m<0 region that will be interesting to explore
experimentally.Comment: 12 pages, LaTeX+Revtex, included 3 postscript figures. To appear in
the Physical Review C (Rapid Communications
Saturation properties of nuclear matter in a relativistic mean field model constrained by the quark dynamics
We have built an effective Walecka-type hadronic Lagrangian in which the
hadron masses and the density dependence of the coupling constants are deduced
from the quark dynamics using a Nambu-Jona-Lasinio model. In order to stabilize
nuclear matter an eight-quark term has been included. The parameters of this
Nambu-Jona-Lasinio model have been determined using the meson properties in the
vacuum but also in the medium through the omega meson mass in nuclei measured
by the TAPS collaboration. Realistic properties of nuclear matter have been
obtained.Comment: 14 pages, 2 figures, submitted to Nuclear Physics
Relativistic versus Nonrelativistic Optical Potentials in A(e,e'p)B Reactions
We investigate the role of relativistic and nonrelativistic optical
potentials used in the analysis of () data. We find that the
relativistic calculations produce smaller () cross sections even in the
case in which both relativistic and nonrelativistic optical potentials fit
equally well the elastic proton--nucleus scattering data. Compared to the
nonrelativistic impulse approximation, this effect is due to a depletion in the
nuclear interior of the relativistic nucleon current, which should be taken
into account in the nonrelativistic treatment by a proper redefinition of the
effective current operator.Comment: Added one new figure, the formalism section has been enlarged and the
list of references updated. Added one appendix. This version will appear in
Phys. Rev. C. Revtex 3.0, 6 figures (not included). Full postscript version
of the file and figures available at
http://www.nikhefk.nikhef.nl/projects/Theory/preprints
Spectroscopic Factors in Ca and Pb from : Fully Relativistic Analysis
We present results for spectroscopic factors of the outermost shells in
Ca and Pb, which have been derived from the comparison between
the available quasielastic () data from NIKHEF-K and the corresponding
calculated cross-sections obtained within a fully relativistic formalism. We
include exactly the effect of Coulomb distortion on the electron wave functions
and discuss its role in the extraction of the spectroscopic factors from
experiment. Without any adjustable parameter, we find spectroscopic factors of
about 70\%, consistent with theoretical predictions. We compare our results
with previous relativistic and nonrelativistic analyses of () data. In
addition to Coulomb distortion effects we discuss different choices of the
nucleon current operator and also analyze the effects due to the relativistic
treatment of the outgoing-distorted and bound nucleon wave functions.Comment: 9 pages RevTeX, 5 figures can be obtained from the author
UMIS & urban habilitation in Venezuela
The paper describes the Urban Management Information System (UMIS) designed to monitor
and evaluated the execution of the Actions and Investments Program (AIP) elaborate
with the actors implied in the urban HABILITATION of neighbourhoods, policy implemented
by the National Housing Counsel (CONAVI) in Venezuela. This Geographical Information
and Territorial Management System, permits the visualization and recognition
of the plan’s advance through the execution of the AIP and makes possible the application
of corrective actions to achieve a sustainable habitat, all of which impacts positively
the quality of life in poor neighbourhoods, the urban agents legitimacy and the local gobernability.Peer Reviewe
Optimization of Phenolic Antioxidant Extraction from Wuweizi (Schisandra chinensis) Pulp Using Random-Centroid Optimazation Methodology
The extraction optimization and composition analysis of polyphenols in the fresh pulp of Wuweizi (Schisandra chinensis) have been investigated in this study. The extraction process of polyphenols from Wuweizi pulp was optimized using Random-Centroid Optimization (RCO) methodology. Six factors including liquid and solid ratio, ethanol concentration, pH, temperature, heating time and extraction times, and three extraction targets of polyphenol content, antioxidant activity and extract yield were considered in the RCO program. Three sets of optimum proposed factor values were obtained corresponding to three extraction targets respectively. The set of optimum proposed factor values for polyphenol extraction given was chosen in further experiments as following: liquid and solid ratio (v/w) 8, ethanol 67.3% (v/v), initial pH 1.75, temperature 55 °C for 4 h and extraction repeated for 4 times. The Wuweizi polyphenol extract (WPE) was obtained with a yield of 16.37 mg/g and composition of polyphenols 1.847 mg/g, anthocyanins 0.179 mg/g, sugar 9.573 mg/g and protein 0.327 mg/g. The WPE demonstrated high scavenging activities against DPPH radicals
Self-consistent Green's function method for nuclei and nuclear matter
Recent results obtained by applying the method of self-consistent Green's
functions to nuclei and nuclear matter are reviewed. Particular attention is
given to the description of experimental data obtained from the (e,e'p) and
(e,e'2N) reactions that determine one and two-nucleon removal probabilities in
nuclei since the corresponding amplitudes are directly related to the imaginary
parts of the single-particle and two-particle propagators. For this reason and
the fact that these amplitudes can now be calculated with the inclusion of all
the relevant physical processes, it is useful to explore the efficacy of the
method of self-consistent Green's functions in describing these experimental
data. Results for both finite nuclei and nuclear matter are discussed with
particular emphasis on clarifying the role of short-range correlations in
determining various experimental quantities. The important role of long-range
correlations in determining the structure of low-energy correlations is also
documented. For a complete understanding of nuclear phenomena it is therefore
essential to include both types of physical correlations. We demonstrate that
recent experimental results for these reactions combined with the reported
theoretical calculations yield a very clear understanding of the properties of
{\em all} protons in the nucleus. We propose that this knowledge of the
properties of constituent fermions in a correlated many-body system is a unique
feature of nuclear physics.Comment: 110 pages, accepted for publication on Prog. Part. Nucl. Phy
Quaiselastic scattering from relativistic bound nucleons: Transverse-Longitudinal response
Predictions for electron induced proton knockout from the and
shells in O are presented using various approximations for the
relativistic nucleonic current. Results for the differential cross section,
transverse-longitudinal response () and left-right asymmetry
are compared at (GeV/c) corresponding to TJNAF experiment
89-003. We show that there are important dynamical and kinematical relativistic
effects which can be tested by experiment.Comment: 10 pages, including 2 figures. Removed preliminary experimental data
from the figure
Axion monodromy in a model of holographic gluodynamics
The low energy field theory for N type IIA D4-branes at strong 't Hooft
coupling, wrapped on a circle with antiperiodic boundary conditions for
fermions, is known to have a vacuum energy which depends on the angle
for the gauge fields, and which is a multivalued function of this angle. This
gives a field-theoretic realization of "axion monodromy" for a nondynamical
axion. We construct the supergravity solution dual to the field theory in the
metastable state which is the adiabatic continuation of the vacuum to large
values of . We compute the energy of this state and show that it
initially rises quadratically and then flattens out. We show that the glueball
mass decreases with , becoming much lower than the 5d KK scale
governing the UV completion of this model. We construct two different classes
of domain walls interpolating between adjacent vacua. We identify a number of
instability modes -- nucleation of domain walls, bulk Casimir forces, and
condensation of tachyonic winding modes in the bulk -- which indicate that the
metastable branch eventually becomes unstable. Finally, we discuss two
phenomena which can arise when the axion is dynamical; axion-driven inflation,
and axion strings.Comment: 43 pages, 10 figures. v2: references update
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