26,343 research outputs found
Abell 2111: An Optical and Radio Study of the Richest Butcher-Oemler Cluster
We present an in-depth analysis of the Butcher-Oemler cluster A2111,
including new optical spectroscopy plus a deep Very Large Array (VLA) radio
continuum observation. These are combined with optical imaging from the Sloan
Digital Sky Survey (SDSS) to assess the activity and properties of member
galaxies. Prior X-ray studies have suggested A2111 is a head-on cluster merger,
a dynamical state which might be connected to the high level of activity
inferred from its blue fraction. We are able to directly assess this claim,
using our spectroscopic data to identify 95 cluster members among 196 total
galaxy spectra. These galaxy velocities do not themselves provide significant
evidence for the merger interpretation, however they are consistent with it
provided the system is viewed near the time of core passage and at a viewing
angle >~30 degrees different from the merger axis. The SDSS data allow us to
confirm the high blue fraction for A2111, f_b = 0.15 +/- 0.03 based on
photometry alone and f_b = 0.23 +/- 0.03 using spectroscopic data to remove
background galaxies. We are able to detect 175 optical sources from the SDSS in
our VLA radio data, of which 35 have redshift information. We use the SDSS
photometry to determine photometric redshifts for the remaining 140
radio-optical sources. In total we identify up to 26 cluster radio galaxies, 14
of which have spectroscopic redshifts. The optical spectroscopy and radio data
reveal a substantial population of dusty starbursts within the cluster. The
high blue fraction and prevalence of star formation is consistent with the
hypothesis that dynamically-active clusters are associated with more active
member galaxies than relaxed clusters.Comment: To appear in AJ; 53 pages including 10 figures and several long
table
Cereal and nonfat milk support muscle recovery following exercise
All authors are with the Exercise Physiology and Metabolism Laboratory Department of Kinesiology and Health Education The University of Texas at Austin Austin, TX, USABackground: This study compared the effects of ingesting cereal and nonfat milk (Cereal) and a carbohydrate-electrolyte sports drink (Drink) immediately following endurance exercise on muscle glycogen synthesis and the phosphorylation state of proteins controlling protein synthesis: Akt, mTOR, rpS6 and eIF4E. -- Methods: Trained cyclists or triathletes (8 male: 28.0 ± 1.6 yrs, 1.8 ± 0.0 m, 75.4 ± 3.2 kg, 61.0 ± 1.6 ml O2•kg-1•min-1; 4 female: 25.3 ± 1.7 yrs, 1.7 ± 0.0 m, 66.9 ± 4.6 kg, 46.4 ± 1.2 mlO2•kg-1•min-1) completed two randomly-ordered trials serving as their own controls. After 2 hours of cycling at 60–65% VO2MAX, a biopsy from the vastus lateralis was obtained (Post0), then subjects consumed either Drink (78.5 g carbohydrate) or Cereal (77 g carbohydrate, 19.5 g protein and 2.7 g fat). Blood was drawn before and at the end of exercise, and at 15, 30 and 60 minutes after treatment. A second biopsy was taken 60 minutes after supplementation (Post60). Differences within and between treatments were tested using repeated measures ANOVA.
-- Results: At Post60, blood glucose was similar between treatments (Drink 6.1 ± 0.3, Cereal 5.6 ± 0.2 mmol/L, p < .05), but after Cereal, plasma insulin was significantly higher (Drink 123.1 ± 11.8, Cereal 191.0 ± 12.3 pmol/L, p < .05), and plasma lactate significantly lower (Drink 1.4 ± 0.1, Cereal 1.00 ± 0.1 mmol/L, p < .05). Except for higher phosphorylation of mTOR after Cereal, glycogen and muscle proteins were not statistically different between treatments. Significant Post0 to Post60 changes occurred in glycogen (Drink 52.4 ± 7.0 to 58.6 ± 6.9, Cereal 58.7 ± 9.6 to 66.0 ± 10.0 μmol/g, p < .05) and rpS6 (Drink 17.9 ± 2.5 to 35.2 ± 4.9, Cereal 18.6 ± 2.2 to 35.4 ± 4.4 %Std, p < .05) for each treatment, but only Cereal significantly affected glycogen synthase (Drink 66.6 ± 6.9 to 64.9 ± 6.9, Cereal 61.1 ± 8.0 to 54.2 ± 7.2%Std, p < .05), Akt (Drink 57.9 ± 3.2 to 55.7 ± 3.1, Cereal 53.2 ± 4.1 to 60.5 ± 3.7 %Std, p < .05) and mTOR (Drink 28.7 ± 4.4 to 35.4 ± 4.5, Cereal 23.0 ± 3.1 to 42.2 ± 2.5 %Std, p < .05). eIF4E was unchanged after both treatments.
-- Conclusion: These results suggest that Cereal is as good as a commercially-available sports drink in initiating post-exercise muscle recovery.Kinesiology and Health [email protected]
Incident-energy and system-size dependence of directed flow
We present STAR's measurements of directed flow for charged hadrons in Au+Au
and Cu+Cu collisions at GeV and 62.4 GeV, as a
function of pseudorapidity, transverse momentum and centrality. We find that
directed flow depends on the incident energy, but not on the system size. We
extend the validity of limiting fragmentation hypothesis to different collision
systems.Comment: Quark Matter 2006 proceedings, 4 pages, 4 figures, submitted to J.
Phys.
Inference on gravitational waves from coalescences of stellar-mass compact objects and intermediate-mass black holes
Gravitational waves from coalescences of neutron stars or stellar-mass black
holes into intermediate-mass black holes (IMBHs) of solar masses
represent one of the exciting possible sources for advanced gravitational-wave
detectors. These sources can provide definitive evidence for the existence of
IMBHs, probe globular-cluster dynamics, and potentially serve as tests of
general relativity. We analyse the accuracy with which we can measure the
masses and spins of the IMBH and its companion in intermediate-mass ratio
coalescences. We find that we can identify an IMBH with a mass above with confidence provided the massive body exceeds . For source masses above , the best measured
parameter is the frequency of the quasi-normal ringdown. Consequently, the
total mass is measured better than the chirp mass for massive binaries, but the
total mass is still partly degenerate with spin, which cannot be accurately
measured. Low-frequency detector sensitivity is particularly important for
massive sources, since sensitivity to the inspiral phase is critical for
measuring the mass of the stellar-mass companion. We show that we can
accurately infer source parameters for cosmologically redshifted signals by
applying appropriate corrections. We investigate the impact of uncertainty in
the model gravitational waveforms and conclude that our main results are likely
robust to systematics.Comment: 9 pages, 11 figure
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