Recent progress on the determination of the symmetry Energy

We summarize the current status on constraining the density dependence of the symmetry energy from terrestrial laboratory measurements and astrophysical observations. While the value $E_{sym}({\rho_{0}})$ and density slope $L$ of the symmetry energy at saturation density $\rho_{0}$ can vary largely depending on the data or methods, all the existing constraints are essentially consistent with $E_{sym}({\rho_{0}}) = 31 \pm 2$ MeV and $L = 50 \pm 20$ MeV. The determination of the supra-saturation density behavior of the symmetry energy remains a big challenge.Comment: 12 pages, 2 figures. Plenary talk at 14th National Conference on Nuclear Structure in China, Huzhou, Zhejiang, 12-16 April, 201

Symmetry energy systematics and its high density behavior

We explore the systematics of the density dependence of nuclear matter symmetry energy in the ambit of microscopic calculations with various energy density functionals, and find that the symmetry energy from subsaturation density to supra-saturation density can be well determined by three characteristic parameters of the symmetry energy at saturation density $\rho_0$, i.e., the magnitude $E_{\text{sym}}({\rho_0 })$, the density slope $L$ and the density curvature $K_{\text{sym}}$. This finding opens a new window to constrain the supra-saturation density behavior of the symmetry energy from its (sub-)saturation density behavior. In particular, we obtain $L=46.7 \pm 12.8$ MeV and $K_{\text{sym}}=-166.9 \pm 168.3$ MeV as well as $E_{\text{sym}}({2\rho _{0}}) \approx 40.2 \pm 12.8$ MeV and $L({2\rho _{0}}) \approx 8.9 \pm 108.7$ MeV based on the present knowledge of $E_{\text{sym}}({\rho_{0}}) = 32.5 \pm 0.5$ MeV, $E_{\text{sym}}({\rho_c}) = 26.65 \pm 0.2$ MeV and $L({\rho_c}) = 46.0 \pm 4.5$ MeV at $\rho_{\rm{c}}= 0.11$ fm$^{-3}$ extracted from nuclear mass and the neutron skin thickness of Sn isotopes. Our results indicate that the symmetry energy cannot be stiffer than a linear density dependence.In addition, we also discuss the quark matter symmetry energy since the deconfined quarks could be the right degree of freedom in dense matter at high baryon densities.Comment: 10 pages, 5 figures. Contribution to International Workshop on Multi facets of Eos and Clustering (IWM-EC 2014), May 6-9, 2014, Catania, Ital

Formation of Sco X-1 induced by anomalous magnetic braking of Ap/Bp stars

Sco X-1 is the brightest persistent X-ray in the sky. It is generally believed that Sco X-1 is a low-mass X-ray binary containing a neutron star accreting from a low-mass donor star where mass transfer is driven by the magnetic braking. However, the mass transfer rate predicted by the standard magnetic braking model is at least one order of magnitude lower than the one inferred by X-ray luminosity. In this work, we investigate whether this source could evolved from an intermediate-mass X-ray binary including Ap/Bp stars with a slightly strong magnetic field of 300 - 1000 G. The coupling between the magnetic field and an irradiation-driven wind induced by the X-ray flux from the accretor can yield a strong magnetic braking, which could give rise to a relatively high mass transfer rate. According to the observed orbital period, the mass transfer rate, the mass ratio, and the donor star spectral type, the progenitor of Sco X-1 should be an intermediate-mass X-ray binary including a 1.6 $-$ 1.8 $\rm M_{\odot}$ Ap/Bp donor star in a 1.3 $-$ 1.5 day orbit. Therefore, we propose that anomalous magnetic braking of Ap/Bp stars provides an alternative evolutionary channel to a part of luminous X-ray sources.Comment: 7 pages, 5 figures, accepted for publication in A&

The effects of an individualized diet and exercise program on body fat levels in Taiwanese females aged 40-60 : a thesis presented in partial fulfillment of the requirements for the degree of Master in Nutritional Science

Obesity is increasingly common throughout the world and is associated with significant health problems. Middle-aged migrant women are one of the risk groups for obesity. Their body fat levels increase because of their age and menopause experiences. Besides, the change of lifestyle and eating habits after immigration also affects their body fat levels. Recent studies show the combination of diet and exercise may decrease body fat levels. This study is to observe the effects of a short-term diet and exercise intervention on body fat levels in middle-aged Taiwanese women in New Zealand. Thirty Taiwanese women aged between 40-60, who currently live in New Zealand were enrolled in this study. Body weight, height, skinfolds and circumferences were measured before and after the study. Subjects also completed a 24-hr diet recall, three-day diet record and answered a questionnaire to provide general information and an assessment of physical activity levels. Subjects were divided into an intervention group (n=17) and a control group (n=10). In the intervention group, subjects were given a personal diet and exercise program for 9 weeks according to their diet and physical activity levels subjects in the control group stayed with their own previous diet and exercise habits without any modification. The results of this study showed no significant differences (P>0.05) in body weight between both groups. However, body fat levels in the intervention group decreased significantly (p<0.001) compared to the control group. It was also found that subjects who had higher initial body weight and BMI, lost more body weight during the intervention. Besides, subjects who were more active during the intervention lost more weight. It was concluded that a short-term diet and exercise interventions might decrease body fat levels in middle-aged Taiwanese women in New Zealand