544 research outputs found

    Statistical and thermal properties of mesoscopic systems: application to the many-nucleon system

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    The dissertation investigates the statistical and thermal properties of mesoscopic systems and applies it to the multi-nucleon systems. The investigation was carried out using four approaches starting from the simplest and progressing to the more sophisticated. The first approach develops and employs the three-dimensional simple harmonic oscillator (3D-SHO) quantum statistics to obtain the thermal properties of multi-particle systems. The recently discovered method that relates the single particle oscillator properties to the multi particle oscillator is applied. The approach is successful in predicting observables at temperatures beginning slightly above the ground state domain for nuclear systems. The 3D-SHO potential function is spherically symmetric because the value of the potential depends only on distance. Because of this high degree of symmetry, the states of the three-dimension SHO are highly degenerate. Accordingly, the 3D-SHO approach has a limited capability to address the intrashell excitations, which significantly limits the utility of the predicted level density of the system, especially at low excitation energies. To account more completely for the intrashell effect, a second approach is introduced. In this approach, the single particle states of a temperature-independent mean field Hamiltonian are generated. Those states are used as an input to generate thermally populated states of the desired multi-fermion system. The thermal population procedures are similar to those used with the single particle 3D-SHO. The approach involves an un-physical condensation of the fermions at the very low temperature range. Above this un-physical condensation region, however, the approach gives a good description for the nuclear level densities. Due to computational obstacles, the range of unphysical condensation temperature is undetermined for nuclei with mass number larger than 24 and this limits the application of the mean-field approach at the present time. In attempting to improve the fundamental concepts of the quantum statistics, Tsallis\u27 description for statistical mechanics, which introduces a new parameter, is investigated in some detail. We advance this theory by introducing the generalized-thermodynamic relations and expand the applications of the theory to include many fermion systems for a certain range of the new parameter in this approach. The additional parameter introduced by Tsallis suppresses the thermal response of the system at a given temperature. Ultimately, theory must derive this parameter from the Hamiltonian dynamics in order for the theory to have true predictive power. The last investigation employs the moment method to predict the nuclear level density from the Hamiltonian. This involves extracting the central moment of a fully microscopic no-core shell model Hamiltonian and using the Gram-Charlier expansion function to represent the level density of the system. The key advantage is that one can compute these moments without having to compute the full many-body spectra. The results are encouraging and imply that the no-core shell model can be used to predict nuclear level densities for heavy nuclei in larger model spaces, i.e. for situations beyond the conventional direct diagonalization techniques. A further improvement to the moment method using configuration moments approach is also investigated

    Comprehension and performance in second language acquisition : a study of second language learners' production of modified comprehensible output.

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    SIGLEAvailable from British Library Document Supply Centre- DSC:D95515 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Review of Gamow-Teller and Fermi Transition Strength Functions

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    We studied the temperature effect in isospin-singlet pairings in Gamow-Teller excitations. We use theories of a hole-particle in the mean field shell model studied decay transition using the one-particle-one-hole model for the β\beta-decay of odd-even isotopes and the two-particle-hole models for the β\beta-decay of even-even and/or odd-odd isotopes. Our reference isotopes for the one-particle-one-hole model are \ce{^{15}O}, \ce{^{15}N}, \ce{^{17}F}, and \ce{^{41}Sc}, whereas for the two-particle-hole model we use \ce{^{16}N} (for β\beta^--decay) and \ce{^{56}Ni} and \ce{^{40}Sc} (for β+\beta^+/EC). The calculations involve evaluating the matrix elements of Gamow -Teller and Fermi transitions, then calculate the reduced transition probabilities of Gamow-Teller and Fermi, from which we evaluate the half-lives and the strength function ftft. The results are compared with the available experimental data. For one-particle-one-hole model we found there is a deviation from experimental values which indicates that the model is not valid for beta decay for the even-even nuclei in the ground state due to the residual nucleon-nucleon interaction. As for a two-particle-hole model, we calculated the transition amplitude, from which we calculated the strength of the transition logft\log ft values. We found an excellent agreement between experimental and theoretical results. By drawing the relationship between temperature versus logft\log ft values, we found the general trend is that the strength function values slowly decrease as temperatures increases. There are fluctuations logft\log ft due to the strongly dependent of logft\log ft on the shell configuration of the valence nucleons.Comment: 40 pages, 11 figure

    The Effectiveness of Using Children's Songs in Developing Elementary Graders' English Vocabulary and Pronunciation in Jerusalem, Palestine / Iman I A Shehadeh and Mohammed A A Farrah

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    This study aimed at investigating the effect of using children's songs in developing the elementary graders' vocabulary and pronunciation. It aimed also to investigate teachers' attitudes towards the use of songs in their English classes. The participants were 123 EFL students of the fourth grade; 72 females and 51 males. Arabic is their native language. Both groups are from four private schools in Jerusalem; two groups for boys, and two groups for girls. One boys’ school and one girls’ school were chosen to be the experimental group consisting of 58 participants, while the other boys’ and girls’ schools were chosen to be the control group consisting of 65 participants. Study data were collected via students' pre and post tests and teachers' questionnaire. Exams results showed that students have improved their vocabulary and pronunciation due to the use of songs in learning. Questionnaire results showed that teachers have positive attitudes towards the use of songs in their classes as songs have positive effects in increasing students' achievement, interest and motivation. Finally, results revealed that students' achievements were not affected by gender

    Role of Lean Accounting in Reduction Production Costs in Jordanian Manufacturing Corporation

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    This study is created to identify the role of lean accounting in the reduction of production costs in Jordanian Manufacturing Corporation. To achieve the purposes of the study, the researchers develop a questionnaire consists of (72) items. The population of the study includes of managers of financial departments, workers in the department of human resources and information technology, and workers in the fields of sales, marketing and procurement. The questionnaire has been examined (56) Jordanian manufacturing corporations. The researchers in this work sent a random sample of the questionnaire for all components, which the total of questioners were (280) with average of (5) questionnaires for each company. A total of (242) questionnaires were retrieved, which (227) of them with percentage of 81% were capable of analyzing. On the other hand, (15) questionnaires incapable of analyzing because was uncompleted by the examiners. We can summarize the findings of the study in the following points; first, the most important one is the existence the role of adoption lean accounting in the reduction of production costs in Jordanian Manufacturing Corporation. The study concluded with some recommendations such as the activate the use of the value principle of Lean accounting was more high to eliminate waste and loss, and also to achieve maximum benefits for the company by finding solutions to the problems and obstacles that face the production process. Kaywords: Lean Accounting, Manufacturing Company, Jorda

    Age-related molecular genetic changes of murine bone marrow mesenchymal stem cells

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    <p>Abstract</p> <p>Background</p> <p>Mesenchymal stem cells (MSC) are pluripotent cells, present in the bone marrow and other tissues that can differentiate into cells of all germ layers and may be involved in tissue maintenance and repair in adult organisms. Because of their plasticity and accessibility these cells are also prime candidates for regenerative medicine. The contribution of stem cell aging to organismal aging is under debate and one theory is that reparative processes deteriorate as a consequence of stem cell aging and/or decrease in number. Age has been linked with changes in osteogenic and adipogenic potential of MSCs.</p> <p>Results</p> <p>Here we report on changes in global gene expression of cultured MSCs isolated from the bone marrow of mice at ages 2, 8, and 26-months. Microarray analyses revealed significant changes in the expression of more than 8000 genes with stage-specific changes of multiple differentiation, cell cycle and growth factor genes. Key markers of adipogenesis including lipoprotein lipase, FABP4, and Itm2a displayed age-dependent declines. Expression of the master cell cycle regulators p53 and p21 and growth factors HGF and VEGF also declined significantly at 26 months. These changes were evident despite multiple cell divisions in vitro after bone marrow isolation.</p> <p>Conclusions</p> <p>The results suggest that MSCs are subject to molecular genetic changes during aging that are conserved during passage in culture. These changes may affect the physiological functions and the potential of autologous MSCs for stem cell therapy.</p

    Osteopontin Expression in Cardiomyocytes Is Increased in Pediatric Patients With Sepsis or Pneumonia

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    Sepsis and pneumonia are major causes of death in the United States, and their pathophysiology includes infection with inflammation and immune dysfunction. Both sepsis and pneumonia cause cardiovascular dysfunction. The expression of Osteopontin (OPN) in cardiomyocytes of patients with sepsis or pneumonia, and its role the induced cardiac dysfunction have not been thoroughly investigated. OPN is a matricellular protein synthesized by multiple diseased tissues and cells including cardiomyocytes. Here, we studied the expression of OPN protein using immunofluorescence in human myocardial autopsy tissues from pediatric and mid age or elderly patients with sepsis and/or pneumonia. Fourteen human myocardial tissues from six pediatric patients and eight mid-age or elderly patients were studied. Immunofluorescence was used to investigate the expression of OPN in paraffin-embedded heart sections co-stained with the myocyte markers Actin Alpha 1 (ACTA1) and Myosin Light Chain 2 (MLC2). A quantitative analysis was performed to determine the number of ACTA1 and MLC2 positive cardiomyocytes that express OPN. The results showed that OPN expression was significantly increased in cardiomyocytes in the hearts from pediatric patients with sepsis and/or pneumonia (N = 3) relative to pediatric patients without sepsis/pneumonia (N = 3), or adult to elderly patients with sepsis/pneumonia (N = 5). Among the older septic hearts, higher levels of cardiomyocyte OPN expression was seen only in conjunction with severe coronary arterial occlusion. This is the first study to document increased OPN expression in cardiomyocytes of pediatric subjects with sepsis or pneumonia. Our findings highlight a potentially important role for OPN in sepsis- or pneumonia-mediated cardiac dysfunction in pediatric patients

    Visitor Management System Design and Implementation during the Covid-19 Pandemic

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    In todays computer technology environment, the effect of IT plays a significant part in all real-time systems. Various management systems are in place to help the company organization achieve profit, standards, and future commercial growth. The VMS is important for monitoring how many visitors are there, what the objective of the facility visit will be, and who will be put in the block listed record due to rule violation. This technology also protects the buildings overall security. The goal of this system is to synchronize the organizations business and visitors in order to achieve a wonderful connection among organizations globally. The background was compiled from many papers that discussed similar subjects and were connected to the system. In addition, the limitations and analyses of the present system have been addressed in order to demonstrate the organizations demands for a new system. In part three, we will go through the project planning, covering the feasibility study, Gantt chart, and software methodology in specific stages. Stepping on functional and non- functional requirements of the system, it is covered in the same chapter, as well as the system steps in the implementation part of section four, and finally with clear and direct conclusion and recommendations in section five with future work of the visitor management system, which will be added after the system is implanted in the organization and other related organizations

    Fund Family Selectivity Skills and Market Timing Ability: Comparison Study

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    This study aims to examine fund family performance, in terms of selectivity skills and marketing timing ability, in Saudi Arabia, Malaysia, Indonesia, and Pakistan in 2007–2021. The sample is divided into three levels. First, analysis of the whole sample. Second, analysis by country. Third, analysis of Islamic- and conventional-focused families. The main results are: First, the fund family provides numerous advantages and facilities to managers, for instance diversification opportunities and market research, allowing them to select stocks well. However, their timing ability is still poor. Second, Saudi Arabia has the best performance while Pakistan has the worst performance. Third, as a novel contribution, there are difference in skills and ability between Islamic and conventional family managers due to their difference in main objectives. The findings are important for managers and investors. Managers can position themselves better relative to their competitors, while investors can more effectively allocate their resources to funds that are managed well by fund families

    Dynamic Regulation of Vascular Myosin Light Chain (MYL9) with Injury and Aging

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    Aging-associated changes in the cardiovascular system increase the risk for disease development and lead to profound alterations in vascular reactivity and stiffness. Elucidating the molecular response of arteries to injury and age will help understand the exaggerated remodeling of aging vessels.We studied the gene expression profile in a model of mechanical vascular injury in the iliac artery of aging (22 months old) and young rats (4 months old). We investigated aging-related variations in gene expression at 30 min, 3 d and 7 d post injury. We found that the Myosin Light Chain gene (MYL9) was the only gene differentially expressed in the aged versus young injured arteries at all time points studied, peaking at day 3 after injury (4.6 fold upregulation (p<0.05) in the smooth muscle cell layers. We confirmed this finding on an aging aortic microarray experiment available through NCBI's GEO database. We found that Myl9 was consistently upregulated with age in healthy rat aortas. To determine the arterial localization of Myl9 with age and injury, we performed immunohistochemistry for Myl9 in rat iliac arteries and found that in healthy and injured (30 days post injury) arteries, Myl9 expression increased with age in the endothelial layers.The consistent upregulation of the myosin light chain protein (Myl9) with age and injury in arterial tissue draws attention to the increased vascular permeability and to the age-caused predisposition to arterial constriction after balloon angioplasty
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