1,909 research outputs found

    Kinematic Self-Similar Plane Symmetric Solutions

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    This paper is devoted to classify the most general plane symmetric spacetimes according to kinematic self-similar perfect fluid and dust solutions. We provide a classification of the kinematic self-similarity of the first, second, zeroth and infinite kinds with different equations of state, where the self-similar vector is not only tilted but also orthogonal and parallel to the fluid flow. This scheme of classification yields twenty four plane symmetric kinematic self-similar solutions. Some of these solutions turn out to be vacuum. These solutions can be matched with the already classified plane symmetric solutions under particular coordinate transformations. As a result, these reduce to sixteen independent plane symmetric kinematic self-similar solutions.Comment: 29 pages, accepted for publication in Classical Quantum Gravit

    Cold Plasma Wave Analysis in Magneto-Rotational Fluids

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    This paper is devoted to investigate the cold plasma wave properties. The analysis has been restricted to the neighborhood of the pair production region of the Kerr magnetosphere. The Fourier analyzed general relativistic magnetohydrodynamical equations are dealt under special circumstances and dispersion relations are obtained. We find the xx-component of the complex wave vector numerically. The corresponding components of the propagation vector, attenuation vector, phase and group velocities are shown in graphs. The direction and dispersion of waves are investigated.Comment: 22 pages, 18 figures, accepted for publication in Astrophys. Space Sc

    Psychometric properties of the king spiritual intelligence questionnaire (KSIQ) in physical veterans of Iran-Iraq warfare

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    Aims: The study's purpose was to determine reliability and validity of the King spiritual intelligence questionnaires in veterans of Iran-Iraq Warfare. Methods: In this cross sectional study, 300 veterans of the Iran-Iraq war completed the King spiritual intelligence questionnaires. Principal components analysis (PCA) with varimax rotation was used to assess domain structure of the King spiritual intelligence questionnaires. Internal and external consistency reliability was assessed with Cronbach's alpha and intra-class correlation coefficient (ICC). Results: Internal consistency of King spiritual intelligence questions estimated with Cronbach's alpha, 0.872 and intra-class correlation coefficient (ICC).872 (CI 95%: 0.84 -0.89). The construct validity of the questionnaire was calculated using exploratory factor analysis that showed 3 factors with Eigen values of greater than one, which explained in total 44.7% of the variance. (1, 8 items, α= 0.87; 2, 5. items; α = 0.89; 3, 2 items, α= 0.51). Conclusion: The Persian version of King spiritual intelligence questionnaire demonstrated suitable validity and reliability among the Veterans of Iran-Iraq Warfare. With the consideration of the proper psychometric characteristics, this questionnaire can be used to further research spiritual intelligence in this population

    Energy Distribution associated with Static Axisymmetric Solutions

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    This paper has been addressed to a very old but burning problem of energy in General Relativity. We evaluate energy and momentum densities for the static and axisymmetric solutions. This specializes to two metrics, i.e., Erez-Rosen and the gamma metrics, belonging to the Weyl class. We apply four well-known prescriptions of Einstein, Landau-Lifshitz, Papaterou and Moš\ddot{o}ller to compute energy-momentum density components. We obtain that these prescriptions do not provide similar energy density, however momentum becomes constant in each case. The results can be matched under particular boundary conditions.Comment: 18 pages, accepted for publication in Astrophysics and SpaceScienc

    Prediabetes and diabetes prevalence and risk factors comparison between ethnic groups in the United Arab Emirates

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    The economic growth has paralleled the rise of diabetes and its complications in multiethnic population of United Arab Emirates (UAE). Previous studies have shown that characteristics of diabetes is variable across different ethnicities. The objective of this study was to compare diabetes prevalence and risk factors between UAE nationals and different expatriate's ethnic groups in UAE using data from UAE National Diabetes and Lifestyle Study (UAEDIAB). The UAE nationals made one-fourth (n = 797, 25%) of total cohort and the remaining 75% belonged to immigrants. Across different ethnicities, adjusted prevalence of prediabetes ranged from 8% to 17%, while adjusted prevalence of newly diagnosed diabetes ranged from 3% to 13%. UAE nationals, Arabs non-nationals and Asians had the highest number of pre-diabetic as well as newly diagnosed diabetic patients. Adjusted prevalence of diabetes was highest in UAE nationals (male 21% and female 23%) as well as Asian non-Arabs (male 23% and female 20%), where 40% of both groups fell under the range of either prediabetes or diabetes conditions. Multivariate factors of diabetes versus non-diabetes included older age, ethnicities of Asian non-Arabs and local UAE nationals, family history of diabetes, obesity, snoring, decreased level of high density lipoprotein, elevated levels of triglycerides and blood pressure. In conclusion, diabetes prevalence and risk factors vary across the different ethnic groups in UAE, and hence interventions towards identification and prevention of diabetes should not treat all patients alike

    Matter collineations of Spacetime Homogeneous G\"odel-type Metrics

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    The spacetime homogeneous G\"odel-type spacetimes which have four classes of metrics are studied according to their matter collineations. The obtained results are compared with Killing vectors and Ricci collineations. It is found that these spacetimes have infinite number of matter collineations in degenerate case, i.e. det(Tab)=0(T_{ab}) = 0, and do not admit proper matter collineations in non-degenerate case, i.e. det(Tab)≠0(T_{ab}) \ne 0. The degenerate case has the new constraints on the parameters mm and ww which characterize the causality features of the G\"odel-type spacetimes.Comment: 12 pages, LaTex, no figures, Class. Quantum.Grav.20 (2003) 216

    Charged Perfect Fluid Cylindrical Gravitational Collapse

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    This paper is devoted to study the charged perfect fluid cylindrical gravitational collapse. For this purpose, we find a new analytical solution of the field equations for non-static cylindrically symmetric spacetime. We discuss physical properties of the solution which predict gravitational collapse. It is concluded that in the presence of electromagnetic field the outgoing gravitational waves are absent. Further, it turns out that when longitudinal length reduces to zero due to resultant action of gravity and electromagnetic field, then the end state of the gravitational collapse is a conical singularity. We also explore the smooth matching of the collapsing cylindrical solution to a static cylindrically symmetric solution. In this matching, we take a special choice of constant radius of the boundary surface. We conclude that the gravitational and Coulomb forces of the system balance each other.Comment: 17 pages, 4 figures, accepted for publication in J. Phys. Soc. Jp

    Black Hole Evaporation in a Noncommutative Charged Vaidya Model

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    The aim of this paper is to study the black hole evaporation and Hawking radiation for a noncommutative charged Vaidya black hole. For this purpose, we determine spherically symmetric charged Vaidya model and then formulate a noncommutative Reissner-Nordstro¹\ddot{o}m-like solution of this model which leads to an exact (t−r)(t-r) dependent metric. The behavior of temporal component of this metric and the corresponding Hawking temperature is investigated. The results are shown in the form of graphs. Further, we examine the tunneling process of the charged massive particles through the quantum horizon. It is found that the tunneling amplitude is modified due to noncommutativity. Also, it turns out that black hole evaporates completely in the limits of large time and horizon radius. The effect of charge is to reduce the temperature from maximum value to zero. It is mentioned here that the final stage of black hole evaporation turns out to be a naked singularity.Comment: 25 pages, 36 figures, accepted for publication in J. Exp. Theor. Phy

    Antioxidant, antimicrobial and antiviral properties of herbal materials

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    Recently, increasing public concern about hygiene has been driving many studies to investigate antimicrobial and antiviral agents. However, the use of any antimicrobial agents must be limited due to their possible toxic or harmful effects. In recent years, due to previous antibiotics’ lesser side effects, the use of herbal materials instead of synthetic or chemical drugs is increasing. Herbal materials are found in medicines. Herbs can be used in the form of plant extracts or as their active components. Furthermore, most of the world’s populations used herbal materials due to their strong antimicrobial properties and primary healthcare benefits. For example, herbs are an excellent material to replace nanosilver as an antibiotic and antiviral agent. The use of nanosilver involves an ROS-mediated mechanism that might lead to oxidative stress-related cancer, cytotoxicity, and heart diseases. Oxidative stress further leads to increased ROS production and also delays the cellular processes involved in wound healing. Therefore, existing antibiotic drugs can be replaced with biomaterials such as herbal medicine with high antimicrobial, antiviral, and antioxidant activity. This review paper highlights the antibacterial, antiviral, and radical scavenger (antioxidant) properties of herbal materials. Antimicrobial activity, radical scavenger ability, the potential for antimicrobial, antiviral, and anticancer agents, and efficacy in eliminating bacteria and viruses and scavenging free radicals in herbal materials are discussed in this review. The presented herbal antimicrobial agents in this review include clove, portulaca, tribulus, eryngium, cinnamon, turmeric, ginger, thyme, pennyroyal, mint, fennel, chamomile, burdock, eucalyptus, primrose, lemon balm, mallow, and garlic, which are all summarized. © 2020 by the authors. Licensee MDPI, Basel, Switzerland
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