Integrated HI emission in galaxy groups and clusters

The integrated HI emission from hierarchical structures such as groups and clusters of galaxies can be detected by FAST at intermediate redshifts. Here we propose to use FAST to study the evolution of the global HI content of clusters and groups over cosmic time by measuring their integrated HI emissions. We use the Virgo cluster as an example to estimate the detection limit of FAST, and have estimated the integration time to detect a Virgo type cluster at different redshifts (from z=0.1 to z=1.5). We have also employed a semi-analytic model (SAM) to simulate the evolution of HI contents in galaxy clusters. Our simulations suggest that the HI mass of a Virgo-like cluster could be 2-3 times higher and the physical size could be more than 50\% smaller when redshift increases from z=0.3 to z=1. Thus the integration time could be reduced significantly and gas rich clusters at intermediate redshifts can be detected by FAST in less than 2 hour of integration time. For the local universe, we have also used SAM simulations to create mock catalogs of clusters to predict the outcomes from FAST all sky surveys. Comparing with the optically selected catalogs derived by cross matching the galaxy catalogs from the SDSS survey and the ALFALFA survey, we find that the HI mass distribution of the mock catalog with 20 second of integration time agrees well with that of observations. However, the mock catalog with 120 second integration time predicts much more groups and clusters that contains a population of low mass HI galaxies not detected by the ALFALFA survey. Future deep HI blind sky survey with FAST would be able to test such prediction and set constraints to the numerical simulation models. Observational strategy and sample selections for the future FAST observations of galaxy clusters at high redshifts are also discussed.Comment: 18 pages,5 figure

A RESEARCH OF E-GOVERNMENT WEBSITE PERFORMANCE AND ITS RELATIONS WITH ECONOMIC DEVELOPMENT

The e-government websites (EGWS) provide comprehensive government information contents and online services for residents and become an important interactive platform between province authorities and residents. In this article, we construct a set of systematic, objective, effective, and service-oriented EGWS performance evaluation model, and utilize the quantization methods, analytic hierarchy process(AHP) to evaluate Chinese province EGWS. We have shown the applicability of the EGWS evaluating method using 31 provincial case study. The results indicate that there remains significant variation in the extent to which EGWS deliver government information, online service, interact with residents and using information technology. Furthermore, we utilized correlation analysis to determine whether the EGWS performance has any relations with the economic development level. This research provide e-government policy makers with the ability to make more informed decisions on these issues so residents can be better served

Eight new species of the genera \u3cem\u3eScorpiops\u3c/em\u3e Peters, \u3cem\u3eEuscorpiops\u3c/em\u3e Vachon, and \u3cem\u3eChaerilus\u3c/em\u3e Simon (Scorpiones: Euscorpiidae, Chaerilidae) from Tibet and Yunnan, China

Eight new species belonging to the genera Scorpiops and Euscorpiops (Euscorpiidae: Scorpiopinae) and Chaerilus (Chaerilidae) are described from China. These are: Scorpiops atomatus sp. n., Scorpiops langxian sp. n., Scorpiops luridus sp. n., Scorpiops pococki sp. n., Euscorpiops vachoni sp. n., Euscorpiops shidian sp. n., Euscorpiops karschi sp. n., and Chaerilus tessellatus sp. n. New records are also reported for these three genera, and the taxa are redescribed. Descriptions and redescriptions are based mainly on the material collected in Tibet Autonomous Region and Yunnan Province. Checklists and identification keys for Chinese species of the genus Chaerilus and the subfamily Scorpiopinae are provided