144 research outputs found
Large-angle scattering and quasi-elastic barrier distributions
We study in detail the barrier distributions extracted from large-angle
quasi-elastic scattering of heavy ions at energies near the Coulomb barrier.
Using a closed-form expression for scattering from a single barrier, we compare
the quasi-elastic barrier distribution with the corresponding test function for
fusion. We examine the isocentrifugal approximation in coupled-channels
calculations of quasi-elastic scattering and find that for backward angles, it
works well, justifying the concept of a barrier distribution for scattering
processes. This method offers an interesting tool for investigating unstable
nuclei. We illustrate this for the Mg + Pb reaction, where the
quadrupole collectivity of the neutron-rich Mg remains to be clarified
experimentally.Comment: 26 pages, 10 eps figure
Role of non-collective excitations in heavy-ion fusion reactions and quasi-elastic scattering around the Coulomb barrier
Despite the supposed simplicity of double-closed shell nuclei, conventional
coupled-channels calculations, that include all of the known collective states
of the target and projectile, give a poor fit to the fusion cross section for
the O + Pb system. The discrepancies are highlighted through the
experimental barrier distribution and logarithmic derivative, that are both
well defined by the precise experimental fusion data available. In order to
broaden our search for possible causes for this anomaly, we revisit this system
and include in our calculations a large number of non-collective states of the
target, whose spin, parity, excitation energy and deformation paramter are
known from high-precision proton inelastic-scattering measurements. Although
the new coupled-channels calculations modify the barrier distribution, the
disagreemnt with experiment remains both for fusion and for quasi-elastic (QE)
scattering. We find that the Q-value distributions for large-angle QE
scattering become rapidly more important as the incident energy increases,
reflecting the trend of the experimental data. The mass-number dependence of
the non-collective excitations is discussed.Comment: 8 pages, 7 figure
Probing surface diffuseness of nucleus-nucleus potential with quasielastic scattering at deep sub-barrier energies
We perform a systematic study on the surface property of nucleus-nucleus
potential in heavy-ion reactions using large-angle quasielastic scattering at
energies well below the Coulomb barrier. At these energies, the quasielastic
scattering can be well described by a single-channel potential model.
Exploiting this fact, we point out that systems which involve spherical nuclei
require the diffuseness parameter of around 0.60 fm in order to fit the
experimental data, while systems with a deformed target between 0.8 fm and 1.1
fm.Comment: 6 pages, 6 figure
THE ROLE OF FOLIC ACID IN THE TREATMENT OF MAJOR DEPRESSIVE DISORDER
Objective: Depressive symptoms are the most common neuropsychiatric manifestation of folic acid deficiency. The objective of this research is to determine the role of folic acid in the treatment of major depressive disorder (MDD). Method: 60 outpatients with MDD and matched 30 healthy controls constituted the sample. The Personal Information Form was used to determine the sociodeniographic features of the patient and the control groups. Hamilton Depression Rating Scale (HDRS) and the criteria of MDD of DSM-IV were used to diagnos the MDD. 30 of the outpatients randomly selected as first group they were given fluoxetine (20 mgs per day), the remainders we given fluoxeline (20 mgs per day) and folic acid (5 mgs per day) as the second group. HDRS was applied lo the patients in 7<sup>th</sup>, 14<sup>th</sup>, 28<sup>th</sup>, 42<sup>th</sup> days and to the three groups at the beginning, and was measured serum folic acid levels 0 <sup>th</sup>, 14<sup>th</sup>,. 28 <sup>th</sup>, 42<sup>th</sup> days. After calculating HDRS scores and serum folic acid levels, the data were run on SPSS. The following statistical analyses were used in order to evaluate the data: variance analysis, student's t test. Mann-Whitney U test and Tukey's test. Result At the beginning, HDRS scores of first, second and control groups were 29.10, 26.93, 7.90 respectively. The mean serum folate levels were lower in the first and the second groups than It, controls. The decrease of HDRS scores were found to be faster in the second group than the first group. However, in 42<sup>nd</sup> day, the difference between HDRS scores of the two groups was not significant statistically. Conclusion: As a result, one can say that adding folate to the treatment of MDD may reduce the occurrence and duration of MDD and increase the efficiency of antidepressant treatment
Use of Lactobacillus farciminis to improve antioxidant status of Tuj lambs
The aim of this study was to investigate the effects of Lactobacillus farciminis on growth traits and antioxidant status in preweaning and postweaning Tuj lambs. Twenty lambs were divided into four groups, regardless of gender, with a mean live weight of 7.81 ± 0.50 kg. At the start of the experiment, the average age of the lambs was seven days. During the six-week preweaning period, control (C) lambs were fed with colostrum only, and Lactobacillus farciminis was given orally to the treated lambs at 1 g/day/lamb (L1), 2 g/day/lamb (L2) or 4 g/day/lamb (L3). The experiment continued for a total of 22 weeks. During the first six weeks, bodyweight (BW) increased significantly in L1 at the sixth week. Also during this period, bodyweight gain (BWG) in L2 at 2 - 3 weeks and in L3 at 5 - 6 weeks differed from C. In the subsequent period, BW and BWG were not affected by probiotic supplementation. The effects of probiotic supplementation on malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) were significant throughout the experiment, with the effect on glutathione (GSH) also being important in the first six weeks. Thus, Lactobacillus farciminis provided orally to Tuj breed lambs could be used to improve their antioxidant status without compromising growth
A search for very high energy gamma-ray emission from the starburst galaxy NGC 253 with H.E.S.S
We present the result of 28 hours of observations of the nearby starburst
galaxy NGC 253 with the H.E.S.S. detector in 2003. We find no evidence for very
high energy gamma-ray emission from this object. Gamma-ray emission above 400
GeV from NGC 253 had been reported by the CANGAROO collaboration in 2002. From
the H.E.S.S. data we derive upper limits on the flux above 300 GeV of 1.9 *
10^-12 photons cm^-2 s^-1 for a point-like source and 6.3 * 10^-12 photons
cm^-2 s^-1 for a source of radius 0.5 degrees as reported by CANGAROO, both at
a confidence level of 99%. These upper limits are inconsistent with the
spectrum reported by CANGAROO. The expected very high energy gamma-ray emission
from this object is discussed in the framework of a galactic wind propagation
model.Comment: 7 pages, 3 figure
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