Prospects of the Multi-channel Photometric Survey Telescope in the Cosmological Application of Type Ia Supernovae

The Multi-channel Photometric Survey Telescope(Mephisto)is a real-time,three-color photometric system designed to capture the color evolution of stars and transients accurately.This telescope system can be crucial in cosmological distance measurements of low-redshift(low-z,z■0.1)Type Ia supernovae(SNe Ia).To optimize the capabilities of this instrument,we perform a comprehensive simulation study before its official operation is scheduled to start.By considering the impact of atmospheric extinction,weather conditions,and the lunar phase at the observing site involving the instrumental features,we simulate light curves of SNe Ia obtained by Mephisto.The best strategy in the case of SN Ia cosmology is to take the image at an exposure time of 130 s with a cadence of 3 days.In this condition,Mephisto can obtain hundreds of high-quality SNe Ia to achieve a distance measurement better than 4.5%.Given the on-time spectral classification and monitoring of the Lijiang 2.4 m Telescope at the same observatory,Mephisto,in the whole operation,can significantly enrich the well-calibrated sample of supernovae at low-z and improve the calibration accuracy of high-z SNe Ia.

Stellar Populations of AGN-host Dwarf Galaxies Selected with Different Methods

In this paper we investigate the stellar populations and star formation histories of 235 active galactic nucleus(AGN)-host dwarf galaxies,consisting of four samples identified separately with different methods(i.e.,radio,X-ray,mid-IR and variability),utilizing the synthesis code STARLIGHT and spectra from the Sloan Digital Sky Survey Data Release 8.Our results show that the variability sample is the oldest,while the mid-IR sample is the youngest,for which the luminosity at 4020?is dominated(>50%)by the young population(t<10~8yr).The light-weighted mean stellar age of the whole sample is in general about 0.7 dex younger than the optical sample studied in Cai et al.We compare the population results between fitting models with and without a power-law(PL)component and find that the neglect of a PL component would lead to an under-and over-estimation by 0.2 and0.1 dex for the light-and mass-weighted mean stellar age,respectively,for our sample of dwarf galaxies,which has a mean fractional contribution of~16%from the AGN.In addition,we obtain further evidence for a possible suppression of star formation in the host galaxy by the central AGN.We also find that there exists an anticorrelation between the extinction-corrected[O III]luminosity and light-weighted mean stellar age,confirming our previous finding that there is a physical connection between AGN and star-forming activities in AGN-host dwarfs.

CYP17 T27C polymorphism and prostate cancer risk: a meta-analysis based on 31 studies

Objective：The cytochrome P450 17α-hydroxylase（CYP17）plays a vital role in androgen biosynthesis.A T-to-C polymorphism in the 5＇promoter region of CYP17 has been implicated as a risk factor for prostate cancer,but the results of individual studies are inconclusive or controversial.To derive a more precise estimation of the relationship,we performed an updated meta-analysis from 31 studies based on 27 publications.Methods：A comprehensive search was conducted to examine all the eligible studies of CYP17 polymorphism and prostate cancer risk.We used odds ratios（ORs）with 95%confidence intervals（CIs）to assess the strength of the association.Results：Overall,individuals with CC/CT genotype were not associated with prostate cancer risk （CC vs.TT：OR=1.03,95%CI=0.86-1.24,P=0.72,P heterogeneity 〈0.0001;CT vs.TT：OR=0.99,95%CI=0.87- 1.12,P=0.88,P heterogeneity =0.0006）.In the stratified analysis by ethnicity,there was a significantly increased risk of prostate cancer among individuals of African descent under the recessive model（OR=1.56,95%CI=1.01- 2.39,P=0.04,P heterogeneity =0.65）.Conclusion：This meta-analysis suggested that CYP17 polymorphism might be associated with prostate cancer risk among individuals of African descent.