Stellar populations and evolution of early-type cluster galaxies: Constraints from optical imaging and spectroscopy of z=0.5-0.9 galaxy clusters

We present an analysis of stellar populations and evolutionary history of galaxies in three similarly rich galaxy clusters MS0451.6-0305 (z=0.54), RXJ0152.7-1357 (z=0.83), and RXJ1226.9+3332 (z=0.89); based on high S/N ground-based optical spectroscopy and HST imaging for 17-34 members in each cluster. We find no indication of evolution of sizes or velocity dispersions with redshift at a given dynamical galaxy mass. We establish the Fundamental Plane (FP) and scaling relations between absorption line indices and velocity dispersions. We confirm the steeper FP at z=0.86 compared to the low redshift FP, indicating (under the assumption of passive evolution) the formation redshift, z_form, depends on the galaxy velocity dispersion (or mass). z_form varies from z_form=1.24+-0.05 at velocity dispersion of 125 km/s to 1.95+-0.25 at 225 km/s. The three clusters and the low redshift sample follow similar scaling relations between absorption line indices and velocity dispersions. The strength of the higher order Balmer lines Hdelta and Hgamma implies z_form>2.8. From the line strengths we find that [M/H] for MS0451.6-0305 is about 0.2 dex below that of the other clusters, and confirm our previous result that [alpha/Fe] for RXJ0152.7-1357 is about 0.3 dex higher than that of the other clusters. These differences between the high-redshift clusters and the low redshift sample are inconsistent with a passive evolution scenario for early-type cluster galaxies over the redshift interval studied. (abridged)Comment: Accepted for publication in Astronomical Journal, 77 pages, uses emulateapj.cls, 36 figures. High resolution color figures available by e-mail request to the first autho

RXJ0848.6+4453: The Evolution of Galaxy Sizes and Stellar Populations in a z=1.27 Cluster

RXJ0848.6+4453 (Lynx W) at redshift 1.27 is part of the Lynx Supercluster of galaxies. Our analysis of stellar populations and star formation history in the cluster covers 24 members and is based on deep optical spectroscopy from Gemini North and imaging data from HST. Focusing on the 13 bulge-dominated galaxies for which we can determine central velocity dispersions, we find that these show a smaller evolution of sizes and velocity dispersions than reported for field galaxies and galaxies in poorer clusters. The galaxies in RXJ0848.6+4453 populate the Fundamental Plane similar to that found for lower redshift clusters with a zero point offset corresponding to an epoch of last star formation at z_form= 1.95+-0.2. The spectra of the galaxies in RXJ0848.6+4453 are dominated by young stellar populations at all galaxy masses and in many cases show emission indicating low level on-going star formation. The average age of the young stellar populations (estimated from H-zeta) is consistent with a major star formation episode 1-2 Gyr prior, which in turn agrees with z_form=1.95. Galaxies dominated by young stellar populations are distributed throughout the cluster. We speculate that low level star formation has not yet been fully quenched in the center of this cluster may be because the cluster is significantly poorer than other clusters previously studied at similar redshifts, which appear to have very little on-going star formation in their centers.Comment: Accepted for publication in Astronomical Journal. High-resolution figures available from the first author by reques

The Fundamental Plane in RX J0142.0+2131: a galaxy cluster merger at z=0.28

We present the Fundamental Plane (FP) in the z = 0.28 cluster of galaxies RX J0142.0+2131. There is no evidence for a difference in the slope of the FP when compared with the Coma cluster, although the internal scatter is larger. On average, stellar populations in RX J0142.0+2131 have rest-frame V-band mass-to-light ratios (M/L_V) 0.29+-0.03 dex lower than in Coma. This is significantly lower than expected for a passively-evolving cluster formed at z_f=2. Lenticular galaxies have lower average M/L_V and a distribution of M/L_V with larger scatter than ellipticals. Lower mass-to-light ratios are not due to recent star formation: our previous spectroscopic observations of RX J0142.0+2131 E/S0 galaxies showed no evidence for significant star-formation within the past ~4 Gyr. However, cluster members have enhanced alpha-element abundance ratios, which may act to decrease M/L_V. The increased scatter in the RX J0142.0+2131 FP reflects a large scatter in M/L_V implying that galaxies have undergone bursts of star formation over a range of epochs. The seven easternmost cluster galaxies, including the second brightest member, have M/L_V consistent with passive evolution and z_f = 2. We speculate that RX J0142.0+2131 is a cluster-cluster merger where the galaxies to the east are yet to fall into the main cluster body or have not experienced star formation as a result of the merger.Comment: 4 pages, 2 figures, accepted for publication in ApJ Letter

Physical activity levels among offshore fleet seafarers

Advanced technology has rationalized and simplified operations at sea; however, this development has resulted in higher demands being made of the operator. Good health has become an important safety factor: a good state of health is crucial both to preventing strain injuries and to ensuring alertness and optimal performance at work. Physical activity is a powerful preventive “medicine” for the maintenance of good health and the prevention of overweight and musculoskeletal disorders. The aim of this paper is to analyse the habits and preferences of seafarers with regard to physical activity. Individual health factors, physical activity levels and work-related problems were surveyed on board vessels in a Norwegian shipping company. A questionnaire was completed by 577 seafarers. The results demonstrated that 70% of the respondents exercised twice or more times per week when at home, whereas only 39% exercised on board. Twenty per cent never exercised on board, and 5% never exercised at home. Walking is preferred by 70% of seafarers at home, as well as cycling and doing manual work. On board, walking, cycling and manual work are the most common types of exercise. Strength training is more often preferred on board than at home. Preventing illness and injury, a pleasant and inviting gym on board, and keeping weight under control are the three most important motivational factors. The results show that there is significant potential for improving and organising exercise-related activities on board as a means of maintaining good health and improving the performance of seafarers

Correlating microbial community profiles with geochemical data in highly stratified sediments from the Arctic Mid-Ocean Ridge

Microbial communities and their associated metabolic activity in marine sediments have a profound impact on global biogeochemical cycles. Their composition and structure are attributed to geochemical and physical factors, but finding direct correlations has remained a challenge. Here we show a significant statistical relationship between variation in geochemical composition and prokaryotic community structure within deep-sea sediments. We obtained comprehensive geochemical data from two gravity cores near the hydrothermal vent field Loki’s Castle at the Arctic Mid-Ocean Ridge, in the Norwegian- Greenland Sea. Geochemical properties in the rift valley sediments exhibited strong centimeter-scale stratigraphic variability. Microbial populations were profiled by pyrosequencing from 15 sediment horizons (59,364 16S rRNA gene tags), quantitatively assessed by qPCR, and phylogenetically analyzed. Although the same taxa were generally present in all samples, their relative abundances varied substantially among horizons and fluctuated between Bacteria- and Archaea-dominated communities. By independently summarizing covariance structures of the relative abundance data and geochemical data, using principal components analysis, we found a significant correlation between changes in geochemical composition and changes in community structure. Differences in organic carbon and mineralogy shaped the relative abundance of microbial taxa. We used correlations to build hypotheses about energy metabolisms, particularly of the Deep Sea Archaeal Group, specific Deltaproteobacteria, and sediment lineages of potentially anaerobic Marine Group I Archaea. We demonstrate that total prokaryotic community structure can be directly correlated to geochemistry within these sediments, thus enhancing our understanding of biogeochemical cycling and our ability to predict metabolisms of uncultured microbes in deep-sea sediments

Therapeutic drug monitoring in inflammatory bowel disease : implementation, utilization, and barriers in clinical practice in Scandinavia

Background and aims Therapeutic drug monitoring (TDM) may optimize biologic and thiopurine therapies in inflammatory bowel disease (IBD). The study aimed to investigate implementation and utilization of TDM in Scandinavia. Methods A web-based questionnaire on the use of TDM was distributed to Scandinavian gastroenterologists via the national societies. Results In total, 297 IBD physicians prescribing biologic therapies, equally distributed between community and university hospitals, were included (response rate 42%) (Norway 118 (40%), Denmark 86 (29%), Sweden 50 (17%), Finland 33 (11%), Iceland 10 (3%)). Overall, TDM was applied during biologic therapies by 87%, and for TNF-inhibitors >90%. Among the users, reactive and proactive TDM were utilized by 90% and 63%, respectively. Danish physicians were significantly less inclined to use TDM compared to other Scandinavian countries; (58% vs 98%); OR 0.03 [0.01-0.09], p 10 IBD patients/week (p = 0.005). TDM scenarios were interpreted in accord with available evidence but with discrepancies for proactive TDM. The main barriers to TDM were lack of guidelines (51%) and time lag between sampling and results (49%). TDM of thiopurines was routinely used by 87%. Conclusion TDM of biologic and thiopurine therapies has been broadly implemented into clinical practice in Scandinavia. However, physicians call for TDM guidelines detailing indications and interpretations of test results along with improved test response times.Peer reviewe