Detection of a Substantial Molecular Gas Reservoir in a brightest cluster galaxy at z = 1.7

We report the detection of CO(2-1) emission coincident with the brightest cluster galaxy (BCG) of the high-redshift galaxy cluster SpARCS1049+56, with the Redshift Search Receiver (RSR) on the Large Millimetre Telescope (LMT). We confirm a spectroscopic redshift for the gas of z = 1.7091+/-0.0004, which is consistent with the systemic redshift of the cluster galaxies of z = 1.709. The line is well-fit by a single component Gaussian with a RSR resolution-corrected FWHM of 569+/-63 km/s. We see no evidence for multiple velocity components in the gas, as might be expected from the multiple image components seen in near-infrared imaging with the Hubble Space Telescope. We measure the integrated flux of the line to be 3.6+/-0.3 Jy km/s and, using alpha_CO = 0.8 Msun (K km s^-1 pc^2)^-1 we estimate a total molecular gas mass of 1.1+/-0.1x10^11 Msun and a M_H2/M_star ~ 0.4. This is the largest gas reservoir detected in a BCG above z > 1 to date. Given the infrared-estimated star formation rate of 860+/-130 Msun/yr, this corresponds to a gas depletion timescale of ~0.1Gyr. We discuss several possible mechanisms for depositing such a large gas reservoir to the cluster center -- e.g., a cooling flow, a major galaxy-galaxy merger or the stripping of gas from several galaxies -- but conclude that these LMT data are not sufficient to differentiate between them.Comment: accepted for publication in ApJ Letter

Osmotically driven pipe flows and their relation to sugar transport in plants

In plants, osmotically driven flows are believed to be responsible for translocation of sugar in the pipe-like phloem cell network, spanning the entire length of the plant. In this paper, we present an experimental and theoretical study of transient osmotically driven flows through pipes with semipermeable walls. We extend the experimental work of Eschrich, Evert and Young \cite[]{Eschrich:1972} by providing a more accurate version of their experiment allowing for better comparison with theory. In the experiments we measure the dynamics and structure of a "sugar front", i.e. the transport and decay of a sudden loading of sugar in a pipe which is closed in both ends. We include measurements of pressure inside the membrane tube allowing us to compare the experiments directly with theory and, in particular, to confirm quantitatively the exponential decay of the front in a closed tube.In a novel setup we are able to measure the entire concentration profile as the sugar front moves. In contrast to previous studies we find very good agreement between experiment and theory. In the limit of low axial resistance (valid in our experiments as well as in many cases in plants) we show that the equations can be solved exactly by the method of characteristics yielding, in general, an implicit solution. Further we show that under more general conditions the equations of motion can be rewritten as a single integro-differential equation, which can be readily solved numerically. The applicability of our results to plants is discussed and it is shown that it is probable that the pressure-flow hypothesis can account for short distance transport of sugar in plants.Comment: 34 pages, Submitted to Journal of Fluid Mechanics on May 28, 200

Hydraulic architecture of palms

Journal ArticleThe water transport and storage system of palms is adapted to maintain the primary stem xylem functional over the life of the shoot, and in spite of severe drought. However, our structural information far exceeds our knowledge of vascular function, and these functional considerations bring more questions than answers. The tendency to generalize from limited data on a few species begs the question of how the hydraulic parameters discussed vary between palms with different growth forms and ecologies

Pressure Dependence of the Elastic Moduli in Aluminum Rich Al-Li Compounds

I have carried out numerical first principles calculations of the pressure dependence of the elastic moduli for several ordered structures in the Aluminum-Lithium system, specifically FCC Al, FCC and BCC Li, L1_2 Al_3Li, and an ordered FCC Al_7Li supercell. The calculations were performed using the full potential linear augmented plane wave method (LAPW) to calculate the total energy as a function of strain, after which the data was fit to a polynomial function of the strain to determine the modulus. A procedure for estimating the errors in this process is also given. The predicted equilibrium lattice parameters are slightly smaller than found experimentally, consistent with other LDA calculations. The computed elastic moduli are within approximately 10% of the experimentally measured moduli, provided the calculations are carried out at the experimental lattice constant. The LDA equilibrium shear modulus C11-C12 increases from 59.3 GPa in Al, to 76.0 GPa in Al_7Li, to 106.2 GPa in Al_3Li. The modulus C_44 increases from 38.4 GPa in Al to 46.1 GPa in Al_7Li, then falls to 40.7 GPa in Al_3Li. All of the calculated elastic moduli increase with pressure with the exception of BCC Li, which becomes elastically unstable at about 2 GPa, where C_11-C_12 vanishes.Comment: 17 pages (REVTEX) + 7 postscript figure

Lack of prophylaxis before the onset of acute venous thromboembolism among hospitalized cancer patients: the SWIss Venous ThromboEmbolism Registry (SWIVTER)

Background: Venous thromboembolism (VTE) prophylaxis remains underutilized, particularly in cancer patients. We explored clinical predictors of prophylaxis in hospitalized cancer patients before the onset of acute VTE. Methods: In the SWiss Venous ThromboEmbolism Registry, 257 cancer patients (61 ± 15 years) with acute VTE and prior hospitalization for acute medical illness or surgery within 30 days (91% were at high risk with Geneva VTE risk score ≥3) were enrolled. Results: Overall, 153 (60%) patients received prophylaxis (49% pharmacological and 21% mechanical) before the onset of acute VTE. Outpatient status at the time of VTE diagnosis [odds ratio (OR) 0.31, 95% confidence interval (CI) 0.18-0.53], ongoing chemotherapy (OR 0.51, 95% CI 0.31-0.85), and recent chemotherapy (OR 0.53, 95% CI 0.32-0.88) were univariately associated with the absence of VTE prophylaxis. In multivariate analysis, intensive care unit admission within 30 days (OR 7.02, 95% CI 2.38-20.64), prior deep vein thrombosis (OR 3.48, 95% CI 2.14-5.64), surgery within 30 days (OR 2.43, 95% CI 1.19-4.99), bed rest >3 days (OR 2.02, 95% CI 1.08-3.78), and outpatient status (OR 0.38, 95% CI 0.19-0.76) remained the only independent predictors of thromboprophylaxis. Conclusions: Although most hospitalized cancer patients were at high risk, 40% did not receive any prophylaxis before the onset of acute VTE. There is a need to improve thromboprophylaxis in cancer patients, particularly in the presence of recent or ongoing chemotherap

Explorative data analysis of time series based algorithm features of CMA-ES variants

Algorithms and the Foundations of Software technolog