The Nature of the H2-Emitting Gas in the Crab Nebula

Understanding how molecules and dust might have formed within a rapidly expanding young supernova remnant is important because of the obvious application to vigorous supernova activity at very high redshift. In previous papers, we found that the H2 emission is often quite strong, correlates with optical low-ionization emission lines, and has a surprisingly high excitation temperature. Here we study Knot 51, a representative, bright example, for which we have available long slit optical and NIR spectra covering emission lines from ionized, neutral, and molecular gas, as well as HST visible and SOAR Telescope NIR narrow-band images. We present a series of CLOUDY simulations to probe the excitation mechanisms, formation processes and dust content in environments that can produce the observed H2 emission. We do not try for an exact match between model and observations given Knot 51's ambiguous geometry. Rather, we aim to explain how the bright H2 emission lines can be formed from within the volume of Knot 51 that also produces the observed optical emission from ionized and neutral gas. Our models that are powered only by the Crab's synchrotron radiation are ruled out because they cannot reproduce the strong, thermal H2 emission. The simulations that come closest to fitting the observations have the core of Knot 51 almost entirely atomic with the H2 emission coming from just a trace molecular component, and in which there is extra heating. In this unusual environment, H2 forms primarily by associative detachment rather than grain catalysis. In this picture, the 55 H2-emitting cores that we have previously catalogued in the Crab have a total mass of about 0.1 M_sun, which is about 5% of the total mass of the system of filaments. We also explore the effect of varying the dust abundance. We discuss possible future observations that could further elucidate the nature of these H2 knots.Comment: 51 pages, 15 figures, accepted for publication in MNRAS, revised Figure 12 results unchange

Growth curves of crossbred cows sired by Hereford, Angus, Belgian Blue, Brahman, Boran, and Tuli bulls, and the fraction of mature body weight and height at puberty

The objective of this study was to evaluate the growth curves of females to determine if mature size and relative rates of maturation among breeds differed. Body weight and hip height data were fitted to the nonlinear function BW = f(age) = A − Bek×age, where A is an estimate of mature BW and k determines the rate that BW or height moves from B to A. Cows represented progeny from 28 Hereford, 38 Angus, 25 Belgian Blue, 34 Brahman, 8 Boran, and 9 Tuli sires. Bulls from these breeds were mated by AI to Angus, Hereford, and U.S. Meat Animal Research Center III composite (1/4 Angus, ¼ Hereford, 1/4 Red Poll, and 1/4 Pinzgauer) cows to produce calves in 1992, 1993, and 1994. These matings resulted in 516 mature cows whose growth curves were subsequently evaluated. Hereford-sired cows tended to have heavier mature BW, as estimated by parameter A, than Angus- (P = 0.09) and Brahman-sired cows(P = 0.06), and were heavier than the other breeds (P \u3c 0.001). Angus-sired cows were heavier than Boran-(P \u3c 0.001) and Tuli-sired cows (P \u3c 0.001), and tended to be heavier than Belgian Blue-sired cows (P = 0.097). Angus-sired cows did not differ from Brahman- sired cows (P = 0.94). Brahman-sired cows had a heavier mature BW than Boran- (P \u3c 0.001), Tuli- (P \u3c 0.001), and Belgian Blue-sired cows (P \u3c 0.04). Angus-sired cows matured faster (k) than cows sired by Hereford (P = 0.03), Brahman (P \u3c 0.001), Boran (P = 0.03), and Tuli (P \u3c 0.001) sires, but did not differ from Belgian Blue-sired (P = 0.13) cows. Brahmansired cows took longer to mature than Boran- (P = 0.03) or Belgian Blue-sired cows (P = 0.003). Belgian Blue-sired cows were faster maturing than Tuli-sired cows (P = 0.02). Brahman-sired cows had reached a greater proportion of their mature BW at puberty than had Hereford- (P \u3c 0.001), Tuli- (P = 0.003), and Belgian Blue-sired cows (P = 0.001). Boran-sired cows tended to have reached a greater proportion of their mature BW at puberty than had Angus-sired cows (P = 0.09), and had reached a greater proportion of their mature BW at puberty than had Hereford- (P \u3c 0.001), Tuli- (P \u3c 0.001), and Belgian Blue-sired cows (P \u3c 0.001). Within species of cattle, the relative range in proportion of mature BW at puberty (Bos taurus 0.56 through 0.58, and Bos indicus 0.60) was highly conserved, suggesting that proportion of mature BW is a more robust predictor of age at puberty across breeds than is absolute weight or age

Growth curves of crossbred cows sired by Hereford, Angus, Belgian Blue, Brahman, Boran, and Tuli bulls, and the fraction of mature body weight and height at puberty

The objective of this study was to evaluate the growth curves of females to determine if mature size and relative rates of maturation among breeds differed. Body weight and hip height data were fitted to the nonlinear function BW = f(age) = A − Bek×age, where A is an estimate of mature BW and k determines the rate that BW or height moves from B to A. Cows represented progeny from 28 Hereford, 38 Angus, 25 Belgian Blue, 34 Brahman, 8 Boran, and 9 Tuli sires. Bulls from these breeds were mated by AI to Angus, Hereford, and U.S. Meat Animal Research Center III composite (1/4 Angus, ¼ Hereford, 1/4 Red Poll, and 1/4 Pinzgauer) cows to produce calves in 1992, 1993, and 1994. These matings resulted in 516 mature cows whose growth curves were subsequently evaluated. Hereford-sired cows tended to have heavier mature BW, as estimated by parameter A, than Angus- (P = 0.09) and Brahman-sired cows(P = 0.06), and were heavier than the other breeds (P \u3c 0.001). Angus-sired cows were heavier than Boran-(P \u3c 0.001) and Tuli-sired cows (P \u3c 0.001), and tended to be heavier than Belgian Blue-sired cows (P = 0.097). Angus-sired cows did not differ from Brahman- sired cows (P = 0.94). Brahman-sired cows had a heavier mature BW than Boran- (P \u3c 0.001), Tuli- (P \u3c 0.001), and Belgian Blue-sired cows (P \u3c 0.04). Angus-sired cows matured faster (k) than cows sired by Hereford (P = 0.03), Brahman (P \u3c 0.001), Boran (P = 0.03), and Tuli (P \u3c 0.001) sires, but did not differ from Belgian Blue-sired (P = 0.13) cows. Brahmansired cows took longer to mature than Boran- (P = 0.03) or Belgian Blue-sired cows (P = 0.003). Belgian Blue-sired cows were faster maturing than Tuli-sired cows (P = 0.02). Brahman-sired cows had reached a greater proportion of their mature BW at puberty than had Hereford- (P \u3c 0.001), Tuli- (P = 0.003), and Belgian Blue-sired cows (P = 0.001). Boran-sired cows tended to have reached a greater proportion of their mature BW at puberty than had Angus-sired cows (P = 0.09), and had reached a greater proportion of their mature BW at puberty than had Hereford- (P \u3c 0.001), Tuli- (P \u3c 0.001), and Belgian Blue-sired cows (P \u3c 0.001). Within species of cattle, the relative range in proportion of mature BW at puberty (Bos taurus 0.56 through 0.58, and Bos indicus 0.60) was highly conserved, suggesting that proportion of mature BW is a more robust predictor of age at puberty across breeds than is absolute weight or age

Stellar Archaeology in the Galactic halo with the Ultra-Faint Dwarfs: VI. Ursa Major II

We present a B, V color-magnitude diagram (CMD) of the Milky Way dwarf satellite Ursa Major II (UMa II), spanning the magnitude range from V ~ 15 to V ~ 23.5 mag and extending over a 18 {\times} 18 arcmin2 area centered on the galaxy. Our photometry goes down to about 2 magnitudes below the galaxy's main sequence turn-off, that we detected at V ~ 21.5 mag. We have discovered a bona-fide RR Lyrae variable star in UMa II, which we use to estimate a conservative dereddened distance modulus for the galaxy of (m-M)0 = 17.70{\pm}0.04{\pm}0.12 mag, where the first error accounts for the uncertainties of the calibrated photometry, and the second reflects our lack of information on the metallicity of the star. The corresponding distance to UMa II is 34.7 {\pm} 0.6 ({\pm} 2.0) kpc. Our photometry shows evidence of a spread in the galaxy subgiant branch, compatible with a spread in metal abundance in the range between Z=0.0001 and Z=0.001. Based on our estimate of the distance, a comparison of the fiducial lines of the Galactic globular clusters (GCs) M68 and M5 ([Fe/H]=-2.27 {\pm} 0.04 dex and -1.33 {\pm} 0.02 dex, respectively), with the position on the CMD of spectroscopically confirmed galaxy members, may suggest the existence of stellar populations of different metal abundance/age in the central region of UMa II.Comment: To appear in Ap

Properties of oscillation modes in subgiant stars observed by Kepler

Mixed modes seen in evolved stars carry information on their deeper layers that can place stringent constraints on their physics and on their global properties (mass, age, etc...). In this study, we present a method to identify and measure all oscillatory mode characteristics (frequency, height, width). Analyzing four subgiants stars, we present the first measure of the effect of the degree of mixture on the l=1 mixed modes characteristics. We also show that some stars have measurable l=2 mixed modes and discuss the interest of their measure to constrain the deeper layers of stars.Comment: Accepted to Ap

Active job monitoring in pilots

Recent developments in high energy physics (HEP) including multi-core jobs and multi-core pilots require data centres to gain a deep understanding of the system to monitor, design, and upgrade computing clusters. Networking is a critical component. Especially the increased usage of data federations, for example in diskless computing centres or as a fall-back solution, relies on WAN connectivity and availability. The specific demands of different experiments and communities, but also the need for identification of misbehaving batch jobs, requires an active monitoring. Existing monitoring tools are not capable of measuring fine-grained information at batch job level. This complicates network-aware scheduling and optimisations. In addition, pilots add another layer of abstraction. They behave like batch systems themselves by managing and executing payloads of jobs internally. The number of real jobs being executed is unknown, as the original batch system has no access to internal information about the scheduling process inside the pilots. Therefore, the comparability of jobs and pilots for predicting run-time behaviour or network performance cannot be ensured. Hence, identifying the actual payload is important. At the GridKa Tier 1 centre a specific tool is in use that allows the monitoring of network traffc information at batch job level. This contribution presents the current monitoring approach and discusses recent e_orts and importance to identify pilots and their substructures inside the batch system. It will also show how to determine monitoring data of specific jobs from identified pilots. Finally, the approach is evaluated

Rural Water Districts Costs and Funding

The 1977 Census of Public Water Supplies in Missouri, published by the Missouri Department of Natural Resources, lists 179 public water supply districts serving rural areas and 180 communities in the state. Many Missouri rural areas experienced considerable population growth during the 1970s. As rural population increases, especially in the Ozarks, there will likely occur an increasing need for safe drinking water. In 1977, 34 counties had no rural public water supply districts; 18 of those were in the Ozarks.Reviewed October 1993

Evalution of the Efficacy of the Photosystem II Inhibitor DCMU in Periphyton and Its Effects On Nontarget Microorganisms and Extracellular Enzymatic Reactions

We examined the efficacy of the photosystem II inhibitor 3-(3,4-diclorophenyl)-1,1-dimethyl urea (DCMU) for inhibition of algal photosynthesis in periphyton associated with submerged decomposing litter of Typha angustifolia. We also investigated the possible nontarget effects of DCMU exposure on heterotrophic microorganisms (i.e., bacteria and fungi) and extracellular enzyme activity associated with decaying litter. Standing-dead Typha leaf litter was submerged for 34 and 73 d, returned to the laboratory, and used for controlled laboratory experiments that examined the effect of DCMU on algal ([14C]bicarbonate, pulse-amplitude modulated fluorometry), bacterial ([3H]leucine), and fungal ([14C]acetate) production. Simultaneous assays also were conducted to examine the effect of DCMU on the activities of 4 extracellular enzymes (β-glucosidase, β-xylosidase, leucine-aminopeptidase, and phosphatase). DCMU significantly inhibited algal photosynthesis in light-exposed periphyton (p always \u3c 0.0003), with strong inhibitory effects occurring within 5 min after exposure to DCMU. In contrast, DCMU had no significant direct effect on bacterial (p \u3e 0.5) or fungal production (p \u3e 0.3). Extracellular enzyme activities also were not significantly affected by exposure to DCMU. Heterotrophic microbial and enzyme activity assays were conducted in darkness to avoid any indirect effects of DCMU (i.e., heterotrophic responses to the inhibition of photosynthesis, rather than to DCMU itself). The apparent lack of nontarget effects of DCMU on heterotrophic microbial processes, combined with good efficacy against algal photosynthesis, suggest that DCMU may a useful selective inhibitor for investigations of interactions among litter-inhabiting microbiota

The Nature of the H\u3csub\u3e2\u3c/sub\u3e-Emitting Gas in the Crab Nebula

Understanding how molecules and dust might have formed within a rapidly expanding young supernova remnant is important because of the obvious application to vigorous supernova activity at very high redshift. In previous papers, we have mapped the Crab nebula (the Crab) in a rotovibrational H2emission line, and then measured the molecular excitation temperature for a few of the brighter H2-emitting knots that we have found to be scattered throughout the Crab\u27s filaments. We found that H2 emission is often quite strong, correlates with optical low-ionization emission lines and has a surprisingly high excitation temperature. Here, we study Knot 51, a representative, bright example. It is a spatially isolated structure for which we have available long-slit optical and near-infrared (NIR) spectra covering emission lines from ionized, neutral and molecular gas, as well asHubble Space Telescope visible and Southern Astrophysical Research telescope NIR narrow-band images. We present a series of CLOUDYsimulations to probe the excitation mechanisms, formation processes and dust content in environments that can produce the observed H2 emission. There is still considerable ambiguity about the geometry of Knot 51, so we do not try for an exact match between model and observations. Rather, we aim to explain how the bright H2 emission lines can be formed from within a cloud of the size of Knot 51 that also produces the observed optical emission from ionized and neutral gas. Our models that are powered only by the Crab\u27s synchrotron radiation are ruled out because they are not able to reproduce the observed strong H2 emission coming from thermally populated levels. The simulations that come closest to fitting the observations (although they still have conspicuous discrepancies) have the core of Knot 51 almost entirely atomic with the H2 emission coming from just a trace molecular component, and in which there is extra heating. In this unusual environment, H2 forms primarily through H− by radiative detachment rather than by grain catalysis. In this picture, the 55 H2-emitting cores that we have previously catalogued in the Crab have a total mass of about 0.1 M⊙, which is about 5 per cent of the total mass of the system of filaments. We also explore the effect of varying the dust abundance. We discuss possible future observations that could further elucidate the nature of these H2 knots