1,908 research outputs found

    Transverse parton momenta in single inclusive hadron production in e+e−{e^ + }{e^ - } annihilation processes

    Get PDF
    We study the transverse momentum distributions of single inclusive hadron production in e+e−{e^ + }{e^ - } 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 e+e−{e^ + }{e^ - } annihilations as well. Interesting effects related to its non-perturbative regime can be observed. We test two different parameterizations for the p⊥p_\perp 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 p⊥p_\perp 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

    Low Q2Q^2 proton structure function, using gluon and pseudoscalar meson clouds in the constituent quark framework

    Full text link
    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 Q2Q^2 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 Q2Q^2 value. Since we have access to the parton densities at low Q2Q^2, we are able to obtain F2(x,Q2)F_{2}(x,Q^2) structure function at low Q2Q^2 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 Q2Q^2 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

    Get PDF
    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

    Interior Point Decoding for Linear Vector Channels

    Full text link
    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

    Association between vitamin d deficiencies in sarcoidosis with disease activity, course of disease and stages of lung involvements

    Get PDF
    Background: Despite negative association between 25-hydroxy vitamin D and incidence of many chronic respiratory diseases, this feature was not well studied in sarcoidosis. Current study investigated the association between 25-hydroxy vitamin D deficiency with sarcoidosis chronicity, disease activity, extra-pulmonary skin manifestations, urine calcium level and pulmonary function status in Iranian sarcoidosis patients. Results of this study along with future studies, will supply more effective programs for sarcoidosis treatment. Methods: Eighty sarcoidosis patients in two groups of insufficient serum level and sufficient serum level of 25-hydroxy vitamin D were studied. Course of sarcoidosis was defined as acute and chronic sarcoidosis. Pulmonary function test (PFT) was assessed by spirometry. Skin involvements were defined as biopsy proven skin sarcoidosis. 24-hour urine calcium level was used to specify the disease activity. Stages of lung involvements were obtained by CT-scan and chest X-ray. The statistical analyses were evaluated using Statistical Package for the Social Sciences. Results: A significant negative correlation was obtained between vitamin D deficiency in sarcoidosis patients and disease chronic course and stages two to four of lung involvements. Considering other parameters of the disease and vitamin D deficiency, no significant correlation was detected. Conclusions: In conclusion, results of the current study implies in the role of vitamin 25(OH)D deficiencies in predicting the course of chronic sarcoidosis. Furthermore, it was concluded that vitamin 25(OH)D deficiency can direct pulmonary sarcoidosis toward stage 2–4 of lung involvements

    Simulation of ozone production in a complex circulation region using nested grids

    Get PDF
    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
    • …
    corecore