Noether symmetric minisuperspace model of f(R)f(R) cosmology

We study the metric $f(R)$ cosmology using Noether symmetry approach by utilizing the behavior of the corresponding Lagrangian under infinitesimal generators of the desired symmetry. The existence of Noether symmetry of the cosmological $f(R)$ minisuperspace helps us to find out the form of $f(R)$ function for which such symmetry exist. It is shown that the resulting form for $f(R)$ yields a power law expansion for the cosmic scale factor. We also show that in the corresponding Noether symmetric quantum model, the solutions to the Wheeler-DeWitt equation can be expressed as a superposition of states of the form $e^{iS}$. It is shown that in terms of such wavefunctions the classical trajectories can be recovered.Comment: 5 pages, Talk given at "The Grassmannian Conference in Fundamental Cosmology (Grasscosmofun'09)", Szczecin, Poland, 14-19th September 200

A Quantitative Study of Quality of Life (QOL) on Postgraduate Students in Universiti Sains Malaysia

A Quantitative study was done to analysis Quality of Life (QOL) between Iranian and Malay postgraduate students in Universiti Sains Malaysia (USM). For this purpose, data were elicited from 35 Iranian and 35 Malay students through a WHOQOL-BREF questionnaire. WHOQOL-BREF has 26 questions and four broad domains namely: Physical health, Psychological, Social Relationships and Environmental domains. Sample characteristics were determined using means and standard deviation and Independent t-tests uses to consider differences for the domain of QOL in two groups of postgraduate students. The participants were of the same language proficiency. Results showed that the internal consistencies (Cronbach alpha) in physical health, psychological, social Relationships and environmental domains are 0.74, 0.79, 0.61, and 0.72, respectively. Moreover, domains are evaluated 60.5 ±10.6, 62.9±11.3, 64.5±14.5, 60.2±10.1 for Malay postgraduate students, and 66.5±13.5, 64.5±16.1, 63.6±17.7, 59.4±13.4 for Iranian postgraduate students, respectively. According to these results, the physical domain is only significant between two groups (P<0.008). Furthermore, our study indicates QOL is in the middle level (50 – 75 %) for all postgraduate students. This study provides comprehensive information that can be applied to improve education quality in national and international students

A late time accelerated FRW model with scalar and vector fields via Noether symmetry

We study the evolution of a three-dimensional minisuperspace cosmological model by the Noether symmetry approach. The phase space variables turn out to correspond to the scale factor of a flat Friedmann-Robertson-Walker (FRW) model, a scalar field with potential function $V(\phi)$ with which the gravity part of the action is minimally coupled and a vector field of its kinetic energy is coupled with the scalar field by a coupling function $f(\phi)$. Then, the Noether symmetry of such a cosmological model is investigated by utilizing the behavior of the corresponding Lagrangian under the infinitesimal generator of the desired symmetry. We explicitly calculate the form of the coupling function between the scalar and the vector fields and also the scalar field potential function for which such symmetry exists. Finally, by means of the corresponding Noether current, we integrate the equations of motion and obtain exact solutions for the scale factor, scalar and vector fields. It is shown that the resulting cosmology is an accelerated expansion universe for which its expansion is due to the presence of the vector field in the early times, while the scalar field is responsible of its late time expansion.Comment: 9 pages, 2 figures, typos corrected, Refs. adde

How are galaxies assigned to halos? Searching for assembly bias in the SDSS galaxy clustering

Clustering of dark matter halos has been shown to depend on halo properties beyond mass such as halo concentration, a phenomenon referred to as halo assembly bias. Standard halo occupation models (HOD) in large scale structure studies assume that halo mass alone is sufficient in characterizing the connection between galaxies and halos. Modeling of galaxy clustering can face systematic effects if the number of galaxies within a halo is correlated with other halo properties. Using the Small MultiDark-Planck high resolution $N$-body simulation and the clustering measurements of the Sloan Digital Sky Survey (SDSS) DR7 main galaxy sample, we investigate the extent to which the concentration-dependence of halo occupation can be constrained. Furthermore, we study how allowing for the concentration dependence can improve our modeling of galaxy clustering. Our constraints on HOD with assembly bias suggest that satellite population is not correlated with halo concentration at fixed halo mass. At fixed halo mass, our constraints favor lack of correlation between the occupation of centrals and halo concentration in the most luminous samples ($M_{\rm r}<-21.5,-21$), and modest correlation in the $M_{\rm r}<-20.5,-20, -19.5$ samples. We show that in comparison with abundance-matching mock catalogs, our findings suggest qualitatively similar but modest levels of the impact of halo assembly bias on galaxy clustering. The effect is only present in the central occupation and becomes less significant in brighter galaxy samples. Furthermore, by performing model comparison based on information criteria, we find that in most cases, the standard mass-only HOD model is still favored by the observations.Comment: Accepted for publication in Ap

Trend of stunting, overweight and obesity among children under five years in a rural area in Northern Iran, 1998–2013: Results of three cross-sectional studies

Background: Obesity is a common health problem in the world and the purpose of this study was to identify the trend of overweight, obesity and stunting among children under five from 1998 to 2013 that was carried out in three stages in the villages of Golestan province in the northern Iran (south east of the Caspian Sea). Methods: Three cross-sectional studies with sample sizes of 7575, including 2339, 2749 and 2487 cases were carried out in 1998, 2004 and 2013, respectively. Among 118 villages, 20 were chosen by random sampling and all of the under-five-children in these villages were assessed. For all subjects, a questionnaire was completed and anthropometric indices were measured. Z-score was used for body index classification with following categories: Z ≤ 2SD=Normal or under-nutrition; >2SD Z ≤3SD = Overweight and Z>3SD = Obesity. P-value under 0.05 indicated significance. Results: In 1998, 2004 and 2013, the prevalence of overweight was 8.5% (95% Cl; 7.3–9.6), 3.3% (95% Cl; 2.7–4.0) and 5.2% (95% Cl; 4.2–6.1), that of obesity was 4.6%(95% Cl; 3.8–3.5), 1.2% (95% Cl; 0.8–1.6) and 3.5% (95% Cl; 2.8–4.3), and that of stunting was 32.8% (95% Cl; 31.0–34.6), 13.4% (95% Cl; 12.2–14.6) and 15.7% (95% Cl;14.3–17.2), respectively. In boys, the mean of height was significantly different in all age groups while the mean of weight was significant only at ages 13–24, 37–48 and 49–60 months (P< 0.005 for all). In girls, the mean of height significantly different from 36 months age (P < 0.01) whereas weight difference was significant only at age of 37–48 months (P = 0.002). Conclusion: A heterogenic trend was seen in stunting, overweight and obesity. Although short stature was the main cause of obesity in 1998, extra weight was its major cause in 2013. Renewed increase of obesity among children under-five is considerable in the northern Iran. © 2016, Academy of Medical Sciences of the I.R. Iran