Thermalization of charm quarks in infinite and finite QGP matter

We study the thermalization process of charm quarks in hot and dense matter. The diffusion of heavy quarks is calculated via a Langevin equation, both for a static medium as well as a QGP medium generated by a (3+1)D hydrodynamic model. We define two criteria for the thermalization of the heavy quarks, and observe thermalization times that are longer than the lifetime of the QGP phase for reasonable values of the diffusion constant.Comment: 10 pages, 12 figure

Geometric functionals of fractal percolation

Fractal percolation exhibits a dramatic topological phase transition, changing abruptly from a dust-like set to a system spanning cluster. The transition points are unknown and difficult to estimate. In many classical percolation models the percolation thresholds have been approximated well using additive geometric functionals, known as intrinsic volumes. Motivated by the question whether a similar approach is possible for fractal models, we introduce corresponding geometric functionals for the fractal percolation process $F$. They arise as limits of expected functionals of finite approximations of $F$. We establish the existence of these limit functionals and obtain explicit formulas for them as well as for their finite approximations.Comment: 42 pages, 8 figure

ProRefine: Valorisation of forage legumes for both monogastric animals and ruminants through fractionation

ProRefi ne aims to gain new knowledge about local food systems in organic farming based on fractionation of forage legumes, such as lucerne and red clover. We will compare fractionation at harvest (leaves and stems) and post-harvest (juice and pulp). We aim to develop protein feeds that are suitable for monogastric animals such as pigs and poultry and fi ber-rich feeds that can be used by ruminants such as dairy cows. We will develop integrated systems for animal production in organic farming that can be adapted to different regions in Europe and Turkey. Furthermore, we aim to assess the sustainability of such systems regarding economy, social aspects and environmental impact

Optimal decision making for sperm chemotaxis in the presence of noise

For navigation, microscopic agents such as biological cells rely on noisy sensory input. In cells performing chemotaxis, such noise arises from the stochastic binding of signaling molecules at low concentrations. Using chemotaxis of sperm cells as application example, we address the classic problem of chemotaxis towards a single target. We reveal a fundamental relationship between the speed of chemotactic steering and the strength of directional fluctuations that result from the amplification of noise in the chemical input signal. This relation implies a trade-off between slow, but reliable, and fast, but less reliable, steering. By formulating the problem of optimal navigation in the presence of noise as a Markov decision process, we show that dynamic switching between reliable and fast steering substantially increases the probability to find a target, such as the egg. Intriguingly, this decision making would provide no benefit in the absence of noise. Instead, decision making is most beneficial, if chemical signals are above detection threshold, yet signal-to-noise ratios of gradient measurements are low. This situation generically arises at intermediate distances from a target, where signaling molecules emitted by the target are diluted, thus defining a `noise zone' that cells have to cross. Our work addresses the intermediate case between well-studied perfect chemotaxis at high signal-to-noise ratios close to a target, and random search strategies in the absence of navigation cues, e.g. far away from a target. Our specific results provide a rational for the surprising observation of decision making in recent experiments on sea urchin sperm chemotaxis. The general theory demonstrates how decision making enables chemotactic agents to cope with high levels of noise in gradient measurements by dynamically adjusting the persistence length of a biased persistent random walk.Comment: 9 pages, 5 figure

Longitudinal Broadening of Quenched Jets in Turbulent Color Fields

The near-side distribution of particles at intermediate transverse momentum, associated with a high momentum trigger hadron produced in a high energy heavy-ion collision, is broadened in rapidity compared with the jet cone. This broadened distribution is thought to contain the energy lost by the progenitor parton of the trigger hadron. We show that the broadening can be explained as the final-state deflection of the gluons radiated from the hard parton inside the medium by soft, transversely oriented, turbulent color fields that arise in the presence of plasma instabilities. The magnitude of the effect is found to grow with medium size and density and diminish with increasing energy of the associated hadron.Comment: 4 pages, 2 figures, Revtex4, revised version, improved abstract and introductio

Fast, low-ionization emission regions of the planetary nebula M2-42

Spatially resolved observations of the planetary nebula M2-42 (PN G008.2-04.8) obtained with the Wide Field Spectrograph on the Australian National University 2.3 m telescope have revealed the remarkable features of bipolar collimated jets emerging from its main structure. Velocity-resolved channel maps derived from the [N II] $\lambda$6584 emission line disentangle different morphological components of the nebula. This information is used to develop a three-dimensional morpho-kinematic model, which consists of an equatorial dense torus and a pair of asymmetric bipolar outflows. The expansion velocity of about 20 km s$^{-1}$ is measured from the spectrum integrated over the main shell. However, the deprojected velocities of the jets are found to be in the range of 80-160 km s$^{-1}$ with respect to the nebular center. It is found that the mean density of the collimated outflows, 595 $\pm$ 125 cm$^{-3}$, is five times lower than that of the main shell, 3150 cm$^{-3}$, whereas their singly ionized nitrogen and sulfur abundances are about three times higher than those determined from the dense shell. The results indicate that the features of the collimated jets are typical of fast, low-ionization emission regions.Comment: 6 pages, 4 figures, 4 tables, accepted for publication in The Astronomical Journa

Early or Normal Cut Grass Silage for Dairy Cows in Organic Farming

Early cut organic grass silage (roundbales) was compared with silage harvested 17 days (180 daydegrees) later in a continuous production experiment with 32 Norwegian Red dairy cows in early lactation. The experiment was carried out in Bodø, Norway. A half of the cows received a feed ration with 40% concentrates (H), and the other half 10% (L) on an annual energy basis. Feeding early cut silage of an organic ley increased feed intake, milk yield and milk protein concentration compared with normal cut. Left-overs of concentrates were a problem in the experiment and ways to improve the palatability of on farm produced cereals have to be developed. Early cut crop yields were only about half of the crop yield at normal cut. Therefore early cut may only be recommended to farmers in northern Norway when acerage is not a limiting factor

The effect of fishmeal or peameal on milk fatty acid composition in organic farming

Feed fatty acid (FA) composition influences the FA composition of cow milk. In a continuous production experiment with 32 Norwegian red dairy cows fishmeal (FM) was compared to peameal (PM) as protein supplement to home-grown cereals and grass silage in organic farming. The protein supplements were together with cereals formulated to be isonitrogeneous and isoenergetic (NEL) and were compared at high (HC) and low concentrate (LC) level. The concentrate rations did not affect the intake of silage. Fishmeal resulted in significantly higher milk yield (kg) with a lower fat concentration (HC) compared to PM. Lower concentrations of urea and FFA were found in milk produced with FM compared to PM. Milk flavour and odour was equal or better when FM rather than PM was fed. Fishmeal diets increased significantly the proportions of several long-chain FAs: oleic acid (C18:1c9), vaccenic acid (C18:1c11), CLA (C18:2c9,t11, not significant at HC), C20:0, C18:1t10, and DHA (C22:6 n-3) in milk fat compared to PM. DHA, which is found in high concentrations in FM (14 g/100g FAME), had the most significant increase. The proportion of C18:3 n-3 (ALA) was significantly lower when FM was fed compared to PM. The percentage of saturated FA was significantly lower and the percentage of monounsaturated FA was higher when FM rather than PM was fed. For cows on HC the n-6/n-3 ratio was lower in the FM group than in the PM group, and the ratio was lower at LC than at HC (p = 0.006, interaction p = 0.02). Fishmeal diets included higher proportions of oats than PM diets. Oats have high content of oleic acid and may therefore have influenced the composition of FAs in milk fat as well as the protein supplements. Fishmeal increased the proportion of beneficial FAs without reducing the sensoric quality of milk. It remains unclear whether this is an effect of protein source or an effect of the higher oat proportions in FM diets

The effect of preservation method of barley, maturity of grass silage, and type of protein supplementation on sensoric milk quality in organic farming

Three continuous production experiments and three short term cross over experiments were carried out in Northern Norway to investigate different feeding strategies for dairy cows in organic farming. This paper focuses on the effects on sensoric milk quality. Half of the 32 Norwegian red dairy cows in the production experiments were fed 40% (HC) concentrates (on energy basis per year) and the other half 10% (LC). Twelve cows (HC) participated in the short term cross over experiments. The experimental factors in the continuous production experiments were barley preservation method (P1), grass silage maturity (P2) and type of protein supplement (P3), and in the short term cross over experiments barley preservation method (C1), type of protein supplement (C2) and time for fishmeal feeding (C3). In all experiments the cows were offered grass silage ad libitum, restricted amounts of cereals and protein feeds, and mineral and vitamin supplements. The sensoric quality of milk was in general high. In the production experiments, milk from cows in HC had slightly higher quality than from cows in LC (significant in P2, p = 0.04). Neither the preservation method of barley (dried or ensiled with molasses), maturity of grass silage or type of protein supplement (fishmeal or peameal) influenced the sensoric milk quality significantly. Also in the cross over experiments no effect of the studied factors was found in milk flavour and odour. Early harvested grass silage gave significantly lower FFA contents than grass silage cut at normal time (P2) and FM gave significantly lower FFA concentrations than peameal (P3). These results indicate that organic farmers with different feeding regimes can produce milk of first class sensoric quality. Also the content of FFA has been low in all experiments (except C1). However, feeding regimes containing low levels of concentrates may reduce milk taste slightly

Effect of barley preservation method on milk production and milk quality in organic farming

The effect of dried vs. ensiled barley (cv. Arve) on feed intake, milk yield and quality in organic production was tested in two experiments in Northern Norway. In the first experiment, two groups were given either 40% or 10% concentrated feed (barley) per cow and year, calculated on energy basis. Grass silage was fed ad. lib. Both drying and ensiling preserved barley properly and resulted in approximately the same feed intake and milk production. Cows in the group with 10% barley had lower milk protein concentration than cows in the group with 40% barley. The palatability of barley was in general low, and several cows refused parts of their allowances throughout the experiment. The second experiment had a cross over design with three treatments. The trial was designed to evaluate the effect of preservation method for barley on sensoric milk quality. The cows were fed well-preserved grass silage ad lib. and supplemented with 5.8 kg DM of either dried barley, barley ensiled with molasses, or barley ensiled with a propionic acid-containing additive. All types of barley were well preserved and no negative effect of ensiled barley was observed