X-ray Sources and their Optical Counterparts in the Globular Cluster M4

We report on the Chandra X-ray Observatory ACIS-S3 imaging observation of the Galactic globular cluster M4 (NGC 6121). We detect 12 X-ray sources inside the core and 19 more within the cluster half-mass radius. The limiting luminosity of this observation is Lx~10e29 erg/sec for sources associated with the cluster, the deepest X-ray observation of a globular cluster to date. We identify 6 X-ray sources with known objects and use ROSAT observations to show that the brightest X-ray source is variable. Archival data from the Hubble Space Telescope allow us to identify optical counterparts to 16 X-ray sources. Based on the X-ray and optical properties of the identifications and the information from the literature, we classify two (possibly three) sources as cataclysmic variables, one X-ray source as a millisecond pulsar and 12 sources as chromospherically active binaries. Comparison of M4 with 47 Tuc and NGC 6397 suggests a scaling of the number of active binaries in these clusters with the cluster (core) mass.Comment: 11 pages, 6 figures, accepted for publication in ApJ. Figure 1 and 5 are of reduced qualit

Synthesis and self-assembly of giant porphyrin discs

Contains fulltext : 13852.pdf (publisher's version ) (Open Access

Depressive symptoms, social support, and health-related quality of life: A community-based study in Shanghai, China

BackgroundDepressive symptoms erode both physical and mental aspects of health-related quality of life (HRQoL). Social support (SS) may improve HRQoL through its direct effects or buffering effects. The association among depressive symptoms, SS, and HRQoL has been studied in specific groups, but research in the general adult population remains limited. This study examined the association among depressive symptoms, SS, and HRQoL, including exploring whether SS (including its three dimensions: subjective SS, objective SS and support utilization) mediated or moderated the relationship between depressive symptoms and HRQoL among community-based adults.MethodsWe conducted a cross-sectional survey in six communities in Shanghai, China, and 1642 adult participants with complete information on depressive symptoms and/or SS, and HRQoL were included. Linear regression analysis was used to investigate the association among depressive symptoms, SS, and HRQoL. In addition, we explored the mediating and moderating role of SS in the relationship between depressive symptoms and HRQoL.ResultsMore depressive symptoms were associated with lower physical HRQoL (B = −0.64, p < .001) and lower mental HRQoL (B = −0.83, p < .001). SS (B = 0.07, p = .02), specifically subjective SS (B = 0.09, p = .03), was positively related to mental HRQoL. After adjusting for covariates, we found no evidence for a mediating role of SS in the relationship between depressive symptoms and HRQoL, while SS (subjective SS and objective SS) moderated the association between depressive symptoms and mental HRQoL.LimitationsDue to the low voluntary participation rate of employees, participants represented approximately 50% of the individuals approached, thus limiting the generalizability of our findings. Data collected through self-report scales could lead to information bias.ConclusionsSS does not appear to underlie the relationship between depressive symptoms and HRQoL. However, interventions to increase SS (in particular, subjective SS and objective SS) should be studied to determine whether they may be beneficial in alleviating the adverse impact of depressive symptoms on mental HRQoL

Interstellar X-ray Absorption Spectroscopy of Oxygen, Neon, and Iron with the Chandra LETGS Spectrum of X0614+091

We find resolved interstellar O K, Ne K, and Fe L absorption spectra in the Chandra Low Energy Transmission Grating Spectrometer spectrum of the low mass X-ray binary X0614+091. We measure the column densities in O and Ne, and find direct spectroscopic constraints on the chemical state of the interstellar O. These measurements probably probe a low-density line of sight through the Galaxy and we discuss the results in the context of our knowledge of the properties of interstellar matter in regions between the spiral arms

Positive-Negative Asymmetry of Contact - Experiment

The main aim of the experiment was to test whether there is a stronger effect of negative than positive contact on intergroup attitudes (eg. The ‘positive-negative asymmetry of contact’); and whether these effects of positive and negative contact are moderated by the intensity of the contact experience

Wetenschappelijk jaarverslag 1997

In dit Wetenschappelijk Jaarverslag presenteert de faculteit Rechtsgeleerdheid van de Universiteit Utrecht haar onderzoek uit het verslagjaar 1997