2,718 research outputs found
Fragmentation functions of the pion, kaon, and proton in the NLO approximation: Laplace transform approach
Using repeated Laplace transform, We find an analytical solution for DGLAP
evolution equations for extracting the pion, kaon and proton Fragmentation
Functions (FFs) at NLO approximation. We also study the symmetry breaking of
the sea quarks Fragmentation Functions, and simply
separated them according to their mass ratio. Finally, we calculate the total
Fragmentation Functions of these hadrons and compare them with experimental
data and those from global fits. Our results show a good agreement with the FFs
obtained from global parameterizations as well as with the experimental data.Comment: 16 Pages, 4 Figures, 1 Tabl
Transverse parton momenta in single inclusive hadron production in annihilation processes
We study the transverse momentum distributions of single inclusive hadron
production in annihilation processes. Although the only
available experimental data are scarce and quite old, we find that the
fundamental features of transverse momentum dependent (TMD) evolution,
historically addressed in Drell-Yan processes and, more recently, in
Semi-inclusive deep inelastic scattering processes, are visible in annihilations as well. Interesting effects related to its non-perturbative
regime can be observed. We test two different parameterizations for the
dependence of the cross section: the usual Gaussian distribution and
a power-law model. We find the latter to be more appropriate in describing this
particular set of experimental data, over a relatively large range of
values. We use this model to map some of the features of the data within the
framework of TMD evolution, and discuss the caveats of this and other possible
interpretations, related to the one-dimensional nature of the available
experimental data
Simulation of ozone production in a complex circulation region using nested grids
International audienceDuring ESCOMPTE precampaign (15 June to 10 July 2000), three days of intensive pollution (IOP0) have been observed and simulated. The comprehensive RAMS model, version 4.3, coupled online with a chemical module including 29 species, has been used to follow the chemistry of the zone polluted over southern France. This online method can be used because the code is paralleled and the SGI 3800 computer is very powerful. Two runs have been performed: run1 with one grid and run2 with two nested grids. The redistribution of simulated chemical species (ozone, carbon monoxide, sulphur dioxide and nitrogen oxides) was compared to aircraft measurements and surface stations. The 2-grid run has given substantially better results than the one-grid run only because the former takes the outer pollutants into account. This online method helps to explain dynamics and to retrieve the chemical species redistribution with a good agreement
Interior Point Decoding for Linear Vector Channels
In this paper, a novel decoding algorithm for low-density parity-check (LDPC)
codes based on convex optimization is presented. The decoding algorithm, called
interior point decoding, is designed for linear vector channels. The linear
vector channels include many practically important channels such as inter
symbol interference channels and partial response channels. It is shown that
the maximum likelihood decoding (MLD) rule for a linear vector channel can be
relaxed to a convex optimization problem, which is called a relaxed MLD
problem. The proposed decoding algorithm is based on a numerical optimization
technique so called interior point method with barrier function. Approximate
variations of the gradient descent and the Newton methods are used to solve the
convex optimization problem. In a decoding process of the proposed algorithm, a
search point always lies in the fundamental polytope defined based on a
low-density parity-check matrix. Compared with a convectional joint message
passing decoder, the proposed decoding algorithm achieves better BER
performance with less complexity in the case of partial response channels in
many cases.Comment: 18 pages, 17 figures, The paper has been submitted to IEEE
Transaction on Information Theor
Low proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework
The idea of the meson cloud approach in the chiral quark model has been
extended to include gluon cloud in order to achieve the parton densities in the
nucleon, based on the constitute quark framework. The splitting function of the
quark to the quark-meson and quark-gluon at low value are used to obtain
parton densities in the constituent quark. The phenomenological constituent
model is employed to extract the parton distributions in the proton at low
value. Since we have access to the parton densities at low , we are
able to obtain structure function at low value. The result
is in good agreement with available experimental data and some theoretical
models. To confirm the validity of our calculations, the fraction of total
momentum of proton which is carried by gluon at high and also the
Gottfried sum rule are computed. The results are in good agreement with what
are expected.Comment: 13 pages, 3 figure
The effects of group play therapy on self-concept among 7 to 11 year-old children suffering from thalassemia major
Background: Children suffering from thalassemia have higher levels of depression and lower levels of self-concept. Objectives: The aim of this study was to determine if group play therapy could significantly increase self-concept among children with thalassemia major ages 7 to 11 years old in teaching hospitals of Golestan province, Iran, in 2012. Patients and Methods: In this randomized, controlled clinical trial, 60 children with thalassemia major were randomly assigned to intervention (30 children) and control (30 children) groups. The intervention included eight 45 to 60 minute sessions during four weeks, during which the intervention group received group play therapy. The control group received no interventions. Selfconcept was measured three times using the Piers-Harris children’s self-concept scale: before, immediately after, and a month after the intervention. Results: For the intervention group, results showed that the mean self-concept score was significantly higher at the second point in time compared to the baseline (P 0.05). Conclusions: The results showed that group play therapy improves self-concept in children suffering from thalassemia major. © 2016, Iranian Red Crescent Medical Journal
Fishing trend and fisheries potential analyses for the Persian Gulf and Sea of Oman, 1973-2003
Catch data from Persian Gulf and Sea of Oman during 1973 to 2001 were used to assess the state of the fishery development in these ecosystems. Also, fishery trends were analyzed to determine catch fluctuations during the period. Catch trend for each species from 1997 to 2003 was analyzed and fishing potential of the species for the following year was predicted. Based on the assessments, we can summarize fishing development in the southern waters of Iran into three periods: undeveloped, rapid development stage and developed stage. The undeveloped stage continued till early 1981, continued by a rapid stage until 1997, reaching to maximum level of at this year and continuing ever since. Catch trend analyses for each species during 1997 to 2003 showed different patterns for each species depending on its economic value. However, the mean catch of all species showed a sustainable trend in the two marine ecosystems. It is concluded that the catch quantity for most of the species have already reached a maximum level. Therefore, in order to keep fisheries sustainable in the region, excess fishing should be avoided
Adaptation in Mothers of Educable Mentally Retarded Children
Background: Adaptation is an important process for humans. Children, who are physically or mentally disabled, impose special stresses on their families, parents and in particular on their mothers.
Objectives: This study examines the relationship between the characteristics of mothers who have educable mentally retarded children, and their adaptation based on Roy’s adaptation model.
Patients and Methods: This descriptive study was performed on 40 mothers of educable mentally retarded children referred to the single exceptional school in Aran va Bidgol City, Iran, during 2010 - 11. An adaptation questionnaire based on Roy’s adaptation model and demographic questionnaire were completed by the subjects. The results were analyzed using SPSS software version 16. Descriptive statistics and a Fisher’s exact test were used.
Results: The overall adaptation of mothers was satisfactory. There was a significant relationship between the child’s birth order (P = 0.04) and the time of awareness of the child’s problem (P = 0.02), with adaptation levels in mothers who had a mentally retarded child.
Conclusions: The child’s birth order and the time of awareness of the child’s problem were related to the mother’s adaptation level
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