The microbiological and chemical composition of baled and precision-chop silages on a sample of farms in County Meath

peer-reviewedA Teagasc Walsh Fellowship awarded to J. McEniry supported this study.Baled and precision-chop silages were examined on a sample of farms in the Irish midlands to determine microbiological and chemical composition at feedout. Silage making practices and chemical composition were similar to those in national surveys. Wilting was an integral part of baled silage production and was reflected in a more restricted fermentation (higher pH and water-soluble carbohydrates, with lower fermentation acids and buffering capacity) compared to precision-chop silage. Yeast numbers were higher in baled silage, suggesting a more aerobic environment within the bale. Although the fermentation appeared similar in the outer and inner horizons of baled silage, yeast, lactic acid bacteria and Enterobacteria numbers were higher in the outer horizon suggesting less exacting anaerobiosis adjacent to the surface of the bale

Skatole pattern during the growth period 50 to 100 kg liveweight in entire male pigs of the crossbreed combinations YDxLYD and HxLYD kept in groups of entire male pigs or in groups with dominant female pigs

1. Dominant females do not decrease the skatole and androstenone concentration in entire male pigs being dominated during the growth period from 50-100 kg liveweight (see fig. 1 and 3). 2. The amount of entire male pigs having higher skatole concentrations in blood – corresponding to skatole in backfat > 0.15 µg/g – are surprisingly high at 50 kg and 75 kg liveweight compared to 100 kg (10, 9 and 13 entire male pigs). 3. Furthermore it is not the same pigs having high skatole concentrations during the period from 50 over 75 to 100 kg liveweight. 4. The crossbreed HxLYD had significant higher skatole concentration in backfat at slaughter (100 kg liveweight) compared to the crossbreed YDxLYD (P<0.05)(see fig. 2). However, there was no significant difference in androstenone concentration in backfat at 100 kg liveweight between the 2 crossbreeds (see fig. 3)

The Spectral Dimension of 2D Quantum Gravity

We show that the spectral dimension d_s of two-dimensional quantum gravity coupled to Gaussian fields is two for all values of the central charge c <= 1. The same arguments provide a simple proof of the known result d_s= 4/3 for branched polymers.Comment: 7 pages, Late

A covariant formalism of spin precession with respect to a reference congruence

We derive an effectively three-dimensional relativistic spin precession formalism. The formalism is applicable to any spacetime where an arbitrary timelike reference congruence of worldlines is specified. We employ what we call a stopped spin vector which is the spin vector that we would get if we momentarily make a pure boost of the spin vector to stop it relative to the congruence. Starting from the Fermi transport equation for the standard spin vector we derive a corresponding transport equation for the stopped spin vector. Employing a spacetime transport equation for a vector along a worldline, corresponding to spatial parallel transport with respect to the congruence, we can write down a precession formula for a gyroscope relative to the local spatial geometry defined by the congruence. This general approach has already been pursued by Jantzen et. al. (see e.g. Jantzen, Carini and Bini, Ann. Phys. 215 (1997) 1), but the algebraic form of our respective expressions differ. We are also applying the formalism to a novel type of spatial parallel transport introduced in Jonsson (Class. Quantum Grav. 23 (2006) 1), as well as verifying the validity of the intuitive approach of a forthcoming paper (Jonsson, Am. Journ. Phys. 75 (2007) 463) where gyroscope precession is explained entirely as a double Thomas type of effect. We also present the resulting formalism in explicit three-dimensional form (using the boldface vector notation), and give examples of applications.Comment: 27 pages, 8 figure

A study of major mergers using a multi-phase ISM code

Galaxy interactions are a common phenomenon in clusters of galaxies. Especially major mergers are of particular importance, because they can change the morphological type of galaxies. They have an impact on the mass function of galaxies and they trigger star formation - the main driver of the Galactic Matter Cycle. Therefore, we conducted a study of major mergers by means of a multi-phase ISM code. This code is based on a TREE-SPH-code combined with a sticky particle method allowing for star formation controlled by the properties of a multi-phase ISM. This is in contrast to the usually implemented Schmidt law depending mainly on the gas density. Previously, this code was used on isolated galaxies. Since our star formation recipe is not restricted to a special type of galaxy, it is interesting to apply it to interacting galaxies, too. Our study on major mergers includes a research of global properties of the interacting system, namely the star formation rate and the star formation efficiency, the evaporation and condensation rates, as well as the mass exchange of distinct components, namely stars, diffuse ISM, and clouds. Investigating these properties provides insight to interrelations between various physical processes. The results indicate that the star formation efficiency as well as the evaporation and condensation rates are influenced by the interaction.Comment: 6 pages, 7 figures, to be published in Astronomische Nachrichten (proceedings of Symposium 6 of the JENAM 2008, Vienna

Reaction paths of alane dissociation on the Si(001) surface

Building on our earlier study, we examine the kinetic barriers to decomposition of alane, AlH$_3$, on the Si(001) surface, using the nudged elastic band (NEB) approach within DFT. We find that the initial decomposition to AlH with two H atoms on the surface proceeds without a significant barrier. There are several pathways available to lose the final hydrogen, though these present barriers of up to 1 eV. Incorporation is more challenging, with the initial structures less stable in several cases than the starting structures, just as was found for phosphorus. We identify a stable route for Al incorporation following selective surface hydrogen desorption (e.g. by STM tip). The overall process parallels PH$_3$, and indicates that atomically precise acceptor doping should be possible.Comment: 19 pages, 8 figures, submitted to J. Physics.: Condens. Matte

Simulations of Dust in Interacting Galaxies

A new Monte-Carlo radiative-transfer code, Sunrise, is used to study the effects of dust in N-body/hydrodynamic simulations of interacting galaxies. Dust has a profound effect on the appearance of the simulated galaxies. At peak luminosities, about 90% of the bolometric luminosity is absorbed, and the dust obscuration scales with luminosity in such a way that the brightness at UV/visual wavelengths remains roughly constant. A general relationship between the fraction of energy absorbed and the ratio of bolometric luminosity to baryonic mass is found. Comparing to observations, the simulations are found to follow a relation similar to the observed IRX-Beta relation found by Meurer et al (1999) when similar luminosity objects are considered. The highest-luminosity simulated galaxies depart from this relation and occupy the region where local (U)LIRGs are found. This agreement is contingent on the presence of Milky-Way-like dust, while SMC-like dust results in far too red a UV continuum slope to match observations. The simulations are used to study the performance of star-formation indicators in the presence of dust. The far-infrared luminosity is found to be reliable. In contrast, the H-alpha and far-UV luminosity suffer severely from dust attenuation, and dust corrections can only partially remedy the situation.Comment: 4 pages, 5 figures, to appear in the proceedings of the conference "The Spectral Energy Distribution of Gas-Rich Galaxies", eds. C.C. Popescu & R.J. Tuffs (Heidelberg, October 2004

On the width of handles in two-dimensional quantum gravity

We discuss the average length l of the shortest non-contractible loop on surfaces in the two-dimensional pure quantum gravity ensemble. The value of $\gamma_{str}$ and the explicit form of the loop functions indicate that l diverges at the critical point. Scaling arguments suggest that the critical exponent of l is 1/2. We show that this value of the critical exponent is also obtained for branched polymers where the calculation is straightforward.Comment: 7 pages, 1 ps figure, late