435 research outputs found
Isovector Giant Dipole Resonance from the 3D Time-Dependent Density Functional Theory for Superfluid Nuclei
A fully symmetry unrestricted Time-Dependent Density Functional Theory
extended to include pairing correlations is used to calculate properties of the
isovector giant dipole resonances of the deformed open-shell nuclei 172Yb
(axially deformed), 188Os (triaxially deformed), and 238U (axially deformed),
and to demonstrate good agreement with experimental data on nuclear
photo-absorption cross-sections for two different Skyrme force parametrizations
of the energy density functional: SkP and SLy4.Comment: 5 pages, 3 figures, published versio
Deuteron tensor polarization component T_20(Q^2) as a crucial test for deuteron wave functions
The deuteron tensor polarization component T_20(Q^2) is calculated by
relativistic Hamiltonian dynamics approach. It is shown that in the range of
momentum transfers available in to-day experiments, relativistic effects, meson
exchange currents and the choice of nucleon electromagnetic form factors almost
do not influence the value of T_20(Q^2). At the same time, this value depends
strongly on the actual form of the deuteron wave function, that is on the model
of NN-interaction in deuteron. So the existing data for T_20(Q^2) provide a
crucial test for deuteron wave functions.Comment: 11 pages, 3 figure
Reliability of 1-repetition maximum estimation for upper and lower body muscular strength measurement in untrained middle aged type 2 diabetic patients
Purpose: The 1-repetition maximum (1-RM) test is the gold standard test for evaluating maximal dynamic strength of groups of muscles. However, safety of actual 1-RM testing is questionable in clinical situations such as type 2 diabetes (T2D), where an estimated 1-RM test is preferred. It is unclear if acceptable test retest reliability exists for the estimated 1-RM test in middle aged T2D patients. This study examined the reliability of the estimated 1-RM strength test in untrained middle aged T2D subjects.Methods: Twenty five untrained diabetic males (n=19) and females (n=6) aged 40.7+0.4 years participated in the study. Participants undertook the first estimated 1-RM test for five exercises namely supine bench press, leg press, lateral pull, leg extension and seated biceps curls. A familiarisation session was provided three to five days before the first test. 1-RM was estimated for all participants by Brzycki 1-RM prediction equation. Another identical 1-RM estimation procedure occurred one week after first test. Intraclass correlation coefficients (ICC), paired t-test, standard error of measurement (SEM), Bland-Altman plots, and estimation of 95% CI were used to assess reliability.Results: Test-retest reliability was excellent (ICC2,1=0.98-0.99) for all measurements with the highest for leg extension (ICC2,1=0.99). The SEM was lowest for lateral pull and leg extension exercises. Paired t-tests showed non-significant differences between the means of 2 sessions across three of five exercises.Conclusions: The study findings suggest that estimation of 1-RM is reliable for upper and lower body muscular strength measurement in untrained middle aged T2D patients.https://doi.org/10.5812/asjsm.345493pubpub
Deuteron distribution in nuclei and the Levinger's factor
We compute the distribution of quasideuterons in doubly closed shell nuclei.
The ground states of O and Ca are described in coupling
using a realistic hamiltonian including the Argonne and the
Urbana IX models of two-- and three--nucleon potentials, respectively. The
nuclear wave function contains central and tensor correlations, and correlated
basis functions theory is used to evaluate the distribution of neutron-proton
pairs, having the deuteron quantum numbers, as a function of their total
momentum. By computing the number of deuteron--like pairs we are able to
extract the Levinger's factor and compare to both the available experimental
data and the predictions of the local density approximation, based on nuclear
matter estimates. The agreement with the experiments is excellent, whereas the
local density approximation is shown to sizably overestimate the Levinger's
factor in the region of the medium nuclei.Comment: 26 pages, 8 figures, typeset using REVTe
Evaluation of the total photoabsorption cross sections for actinides from photofission data and model calculations
We have calculated the fission probabilities for 237-Np, 233,235,238-U,
232-Th, and nat-Pb following the absorption of photons with energies from 68
MeV to 3.77 GeV using the RELDIS Monte-Carlo code. This code implements the
cascade-evaporation-fission model of intermediate-energy photonuclear
reactions. It includes multiparticle production in photoreactions on
intranuclear nucleons, pre-equilibrium emission, and the statistical decay of
excited residual nuclei via competition of evaporation, fission, and
multifragmentation processes. The calculations show that in the GeV energy
region the fission process is not solely responsible for the entire total
photoabsorption cross section, even for the actinides: ~55-70% for 232-Th,
\~70-80% for 238-U, and ~80-95% for 233-U, 235-U, and 237-Np. This is because
certain residual nuclei that are created by deep photospallation at GeV photon
energies have relatively low fission probabilities. Using the recent
experimental data on photofission cross sections for 237-Np and 233,235,238-U
from the Saskatchewan and Jefferson Laboratories and our calculated fission
probabilities, we infer the total photoabsorption cross sections for these four
nuclei. The resulting cross sections per nucleon agree in shape and in
magnitude with each other. However, disagreement in magnitude with
total-photoabsorption cross-section data from previous measurements for nuclei
from C to Pb calls into question the concept of a ``Universal Curve'' for the
photoabsorption cross section per nucleon for all nuclei.Comment: 39 pages including 11 figure
Hydrogen bond dissociation and reformation in methanol oligomers following hydroxyl stretch relaxation
Vibrational relaxation and hydrogen bond dynamics in methanol-d dissolved in CCl 4 have been measured with ultrafast infrared pump-probe spectroscopy. We excited the subensemble of methanol-d molecules both accepting and donating hydrogen bonds at ∼2500 cm -1 . Following vibrational relaxation with a ∼500 fs lifetime, the signal does not decay to zero. Rather, the signal increases to a second maximum at ∼4 ps. The decay from the second maximum occurs on two time scales. We propose a model in which hydrogen bond dissociation, following vibrational relaxation, decreases the concentration of methanol-d molecules that accept and donate hydrogen bonds and produce the observed long-lived bleach of the absorption signal. Using a set of coupled kinetic equations, the time constants for hydrogen bond dissociation and reformation have been determined. Hydrogen bond breaking occurs with ∼200 fs and ∼2 ps time constants. We attribute the fast rate to a direct breaking mechanism wherein the excited hydroxyl stretch decays into modes that directly lead to the hydrogen bond dissociation. The slower rate of breaking is attributed to an indirect mechanism wherein the dissociation of hydrogen bonds follows vibrational energy flow from the initially excited molecule to other components of the same oligomer. The final stage of relaxation, after the second maximum, involves reformation of transiently broken hydrogen bonds. The bonds that break directly recover with ∼7 ps and .10 ns time constants, while the bonds that break indirectly recover with ∼20 ps and .10 ns time constants. Experiments conducted on ethanol-d solutions in CCl 4 demonstrate that the same vibrational relaxation and hydrogen bond dynamic events occur with very similar amplitudes and rate constants. Measurements of the rates of spectral diffusion and polarization anisotropy decay via vibrational excitation transfer and orientational relaxation verify that the initial fast decay of the signal is dominated by vibrational relaxation
First measurements of the ^16O(e,e'pn)^14N reaction
This paper reports on the first measurement of the ^16O(e,e'pn)^14N reaction.
Data were measured in kinematics centred on a super-parallel geometry at energy
and momentum transfers of 215 MeV and 316 MeV/c. The experimental resolution
was sufficient to distinguish groups of states in the residual nucleus but not
good enough to separate individual states. The data show a strong dependence on
missing momentum and this dependence appears to be different for two groups of
states in the residual nucleus. Theoretical calculations of the reaction using
the Pavia code do not reproduce the shape or the magnitude of the data.Comment: 10 pages, 11 figures, 2 tables, Accepted for publication in EPJ
Meson-induced correlations of nucleons in nuclear Compton scattering
The non-resonant (seagull) contribution to the nuclear Compton amplitude at
low energies is strongly influenced by nucleon correlations arising from meson
exchange. We study this problem in a modified Fermi gas model, where nuclear
correlation functions are obtained with the help of perturbation theory. The
dependence of the mesonic seagull amplitude on the nuclear radius is
investigated and the influence of a realistic nuclear density on this amplitude
is dicussed. We found that different form factors appear for the static part
(proportional to the enhancement constant ) of the mesonic seagull
amplitude and for the parts, which contain the contribution from
electromagnetic polarizabilities.Comment: 15 pages, Latex, epsf.sty, 9 eps figures
Elastic electron deuteron scattering with consistent meson exchange and relativistic contributions of leading order
The influence of relativistic contributions to elastic electron deuteron
scattering is studied systematically at low and intermediate momentum transfers
( fm). In a -expansion, all leading order
relativistic -exchange contributions consistent with the Bonn OBEPQ models
are included. In addition, static heavy meson exchange currents including boost
terms and lowest order -currents are considered. Sizeable
effects from the various relativistic two-body contributions, mainly from
-exchange, have been found in form factors, structure functions and the
tensor polarization . Furthermore, static properties, viz. magnetic
dipole and charge quadrupole moments and the mean square charge radius are
evaluated.Comment: 15 pages Latex including 5 figures, final version accepted for
publication in Phys.Rev.C Details of changes: (i) The notation of the curves
in Figs. 1 and 2 have been clarified with respect to left and right panels.
(ii) In Figs. 3 and 4 an experimental point for T_20 has been added and a
corresponding reference [48] (iii) At the end of the text we have added a
paragraph concerning the quality of the Bonn OBEPQ potential
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