Ds+ -- Ds- Asymmetry in Photoproduction

Considering of the possible difference in strange and antistrange quark distributions inside nucleon, we investigate the Ds+ -- Ds- asymmetry in photoproduction in the framework of heavy-quark recombination mechanism. We adopt two distribution models of strange sea, those are the light-cone meson-baryon fluctuation model and the effective chiral quark model. Our results show that the asymmetry induced by the strange quark distributions is distinct, which is measurable in experiments. And, there are evident differences between the predictions of our calculation and previous estimation. Therefore, the experimental measurements on the Ds+ -- Ds- asymmetry may impose a unique restriction on the strange-antistrange distribution asymmetry models.Comment: 11 page, 5 figure

DsD_s Asymmetry in Photoproduction

By adopting two models of strange and antistrange quark distributions inside nucleon, the light-cone meson-baryon fluctuation model and the effective chiral quark model, we calculate the $D_s^+ - D_s^-$ asymmetry in photoproduction in the framework of heavy-quark recombination mechanism. We find that the effect of asymmetry of strange sea to the $D_s$ asymmetry is considerable and depending on the different models. Therefore, we expect that with the further study in electroproduction, e.g. at HERA and CEBAF, the experimental measurements on the $D_s^+ - D_s^-$ asymmetry may impose a strong restriction on the strange-antistrange distribution asymmetry models.Comment: 4 pages, talk presented by I. Caprini at the International Conference on QCD and Hadronic Physics, June 16-20 2005, Beijin

A Study on the Correlation Between Sleep Quality and Accidental Injuries Among University Students in Hainan

Objective: To analyze the correlation between sleep quality and accidental injuries among university students in Hainan, and to provide reference for improving injury prevention among university students. Methods: A total of 1100 college students from freshman to Senior Students in three universities in Hainan were selected by multilevel random sampling method, and investigated by Pittsburgh Sleep Quality Index (PSQI) and injury questionnaire. Results: The average PSQI score of Hainan university students was 7.645. In the five dimensions of sleep latency, sleep efficiency, sleep disturbances, sleep medication, and daytime dysfunction, as well as the PSQI total score, the differences between the accidental injury group and the non-accidental injury group were statistically significant (P＜0.01), except for sleep quality and sleep time, all other dimensions and PSIQ total score were higher in the accidental injury group than in the non-accidental injury group. Conclusion: The problem of poor sleep quality among university students in Hainan were widespread, and the occurrence of accidental injuries among university students were related to the sleep quality