19,346 research outputs found

    Bootstrap approximation for the exchange-correlation kernel of time-dependent density functional theory

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    A new parameter-free approximation for the exchange-correlation kernel fxcf_{\rm xc} of time-dependent density functional theory is proposed. This kernel is expressed as an algorithm in which the exact Dyson equation for the response as well as a further approximate condition are solved together self-consistently leading to a simple parameter-free kernel. We apply this to the calculation of optical spectra for various small bandgap (Ge, Si, GaAs, AlN, TiO2_2, SiC), large bandgap (C, LiF, Ar, Ne) and magnetic (NiO) insulators. The calculated spectra are in very good agreement with experiment for this diverse set of materials, highlighting the universal applicability of the new kernel.Comment: 4 figures 5 page

    The Validity of L-F Approximation Method in the Determination of Molecular Force Fields

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    THE SCOPE OF AYURVEDIC MEDICINE AND THERAPY IN THE MANAGMENT OF INFERTILITY

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    Infertility is described as an inability to conceive despite unprotective sex for duration of one year or more. Male, female or both can be a victim for this disorder. There may be many biological causes of infertility including some can be treated with medical or surgical intervention. Ayurveda consider this problem as a cause of deterioration of quality of four factors i.e., time of ovulation, female health in context of reproductive system, quality of sperm and ovum and female’s proper nutrition. There are different treatment methods and medicines used according to the deficit in male, female or in both. Vajikaran drugs like Ashwagandha, Madhuyasthi, Vidarikanda, Gokshura etc., are used in male fertility problems and Satavari, Punarnava, Dasmoola, Aloevera etc., used in female infertility problems. The purificatory procedures like Vamana, Virechana, Basti etc., are also found very effective to improve the quality and strength of required reproductive factors in both sexes. The effect of Uttar basti is also evidenced in different researches to treat female infertility

    Superheavy nuclei in relativistic effective Lagrangian model

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    Isotopic and isotonic chains of superheavy nuclei are analyzed to search for spherical double shell closures beyond Z=82 and N=126 within the new effective field theory model of Furnstahl, Serot, and Tang for the relativistic nuclear many-body problem. We take into account several indicators to identify the occurrence of possible shell closures, such as two-nucleon separation energies, two-nucleon shell gaps, average pairing gaps, and the shell correction energy. The effective Lagrangian model predicts N=172 and Z=120 and N=258 and Z=120 as spherical doubly magic superheavy nuclei, whereas N=184 and Z=114 show some magic character depending on the parameter set. The magicity of a particular neutron (proton) number in the analyzed mass region is found to depend on the number of protons (neutrons) present in the nucleus.Comment: 26 pages, REVTeX, 10 ps figures; changed conten

    Effect of Severe Protein-Energy Malnutrition on Circulating Thyroid Hormones

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    Protein energy malnutrition (PEM) is one of the most common health problems among Bangladeshi children. PEM is known to induce a wide variety of metabolic disorders and some of which may be mediated through alteration of endocrine functions. Both short-term and long-term alterations in nutritional state affect various aspects of thyroid hormone economy, especially peripheral hormone metabolism. Chronic malnutrition is associated with a decreased serum T3 concentration. Serum T4 levels also tend to be slightly decreased because of a modest decrease in iodothyronine binding protein. TSH concentrations and their response to exogenous TRH are usually normal. To identify the effects of severe protein energy malnutrition on circulating iodothyronines especially circulating T3 & T4 and to determine the level of TSH in severe PEM. To compare the levels of thyroid hormones before and after recovery from severe PEM and to identify any correlation with mortality and morbidity. A prospective cross-sectional comparative study was performed in Nutrition block, Department of Pediatrics, Chittagong Medical College Hospital from 01 Dec 2007 to 30 Nov 2008. Patient admitted to nutrition block with severe PEM were included in the study. The levels of T4, T3 and TSH measured by radioimmunoassay (RIA) method. TSH was measured by using Immunoradiometric Assay Kit, IMK-432 produced by Beijing Atom Hitech Co. Ltd, China. T3 and T4 were measured by using Radioimmunoassay Kit (PR), IMK-422 and IMK-419 respectively produced by Beijing Atom Hitech Co. Ltd, China. Data were presented as the percentage of total number of observation. SPSS- Version 15.0 was used for the analysis of data. Student’s t-test, Z-test, χ-square test and Pearson’s correlation test were used for statistical significance. ‘p’ value of < 0.05 were used as the  minimum level of significance. The effect of protein energy malnutrition (PEM) in the children on serum levels of total thyroxine (TT4), total triiodothyronine (TT3) and thyrotropin (TSH) were evaluated. There were 50 children aged 6 to 60 months in the malnutrition group and 22 healthy age and sex matched controls. Serum TT4 and TT3 were all reduced in the malnutrition group. This decrease in TT3 was more significant (p<0.001) in severe malnutrition than in mild PEM. Serum TSH levels in the malnutrition and control groups were similar. These results suggest that the children remained euthyroid and represent an adaptive response to protein energy malnutrition. The results of the above mentioned studies clearly demonstrate that thyroid functions are adversely affected in severe PEM. This was evidenced by reductions in T3 & T4 levels in comparison to control group. Keywords: Protein Energy Malnutrition; Thyroxine; Triiodothyronine; Thyrotropin

    Superheavy nuclei in relativistic effective Lagrangian model

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    Isotopic and isotonic chains of superheavy nuclei are analyzed to search for spherical double shell closures beyond Z=82 and N=126 within the new effective field theory model of Furnstahl, Serot, and Tang for the relativistic nuclear many-body problem. We take into account several indicators to identify the occurrence of possible shell closures, such as two-nucleon separation energies, two-nucleon shell gaps, average pairing gaps, and the shell correction energy. The effective Lagrangian model predicts N=172 and Z=120 and N=258 and Z=120 as spherical doubly magic superheavy nuclei, whereas N=184 and Z=114 show some magic character depending on the parameter set. The magicity of a particular neutron (proton) number in the analyzed mass region is found to depend on the number of protons (neutrons) present in the nucleus.Comment: 26 pages, REVTeX, 10 ps figures; changed conten
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