Susy QCD and High Energy Cosmic Rays 1. Fragmentation functions of Susy QCD

The supersymmetric evolution of the fragmentation functions (or timelike evolution) within N=1 $QCD$ is discussed and predictions for the fragmentation functions of the theory (into final protons) are given. We use a backward running of the supersymmetric DGLAP equations, using a method developed in previous works. We start from the usual QCD parameterizations at low energy and run the DGLAP back, up to an intermediate scale -assumed to be supersymmetric- where we switch-on supersymmetry. From there on we assume the applicability of an N=1 supersymmetric evolution (ESAP). We elaborate on possible application of these results to High Energy Cosmic Rays near the GZK cutoff.Comment: 36 pages, 12 fig

Sorption, Kinetics, and Transport of Selected Heavy Metals in Soil: A Laboratory Study and Modelling Approaches.

The retention and transport behavior of heavy metals in soils is affected by soil chemical heterogeneity. The objectives of this study were to evaluate (i) the effects of heterogeneity on solute transport of heavy metals under steady water flow, (ii) the applicability of single solute and ion exchange isotherms to model Zn and Cd transport in soil columns, (iii) the modelling of the sorption kinetics of Zn under batch and flow conditions, and (iv) the effects of organic matter and iron oxide removal on the kinetics of Zn sorption in soils. A sensitivity analysis showed that site affinity distribution functions describing chemical heterogeneity in soils are directly related to breakthrough behavior of reactive solutes. The general Langmuir-Freundlich and the Rothmund-Kornfeld equations adequately described heavy metal sorption and transport in soil columns for conditions of variable ionic strength. The modelled and measured Zn breakthrough curves in an acidic sandy soil agreed quantitatively whereas Cd transport was qualitatively predicted. Zn and Cd transport in a weakly acidic silt loam soil was only qualitatively described by mass transfer kinetics. The kinetics of Zn retention as measured under batch conditions were described using a multireaction model and a two-site second-order models and were successful only for a narrow concentration range. Based on noncompetitive high affinity and competitive low affinity sorption sites describing Zn-Ca ion exchange a new model was proposed. This model successfully described Zn sorption kinetics in an acidic soil at initial concentrations varying from 0.01 to 100 mg L\sp{-1} between 2 and 288 h. It also qualitatively predicted Zn kinetics as measured by a thin disk flow method with flow interruptions varying from 0.5 min to 30 d. Modelling and experimental results suggest that equilibrium heavy metal-Ca competition governs the retention at high heavy metal concentrations above 0.1 mM, whereas slow noncompetitive sorption processes dominate the low concentrations below 0.1 mM. The removal of organic matter and iron oxides doubled and quadrupled the Zn sorption at low concentrations, respectively and decreased the rate of reaction

The Chalcolithic–Bronze Age transition in southern Iberia under the influence of the 4.2 kyr event? A correlation of climatological and demographic proxies

The end of the third millennium BCE represents (not only) on the Iberian Peninsula the time of transition to the Bronze Age. At the same time this is the time of a general climatic event, the so-called 4.2 ka BP event, which can be observed (in different manifestations) in different regions of the northern hemisphere. By synchronizing cultural and climatic developments and above all by assessing demographic developments and their spatial development, a much-discussed connection between the two phenomena can be made plausible and opens the perspective for further, more detailed research on the interdependence between cultural, demographic and climatological processes. For this purpose, the results of aoristics, 14C sum calibration and the evaluation of the concentration of long-chain n-alkane homologues of terrestrial origin as precipitation predictor are combined, their correlation is presented and possible responses are interpreted from the mapping of the settlement system development. This article provides an initial overview of the current results

Marching at the front and dragging behind: differential αVβ3-integrin turnover regulates focal adhesion behavior

Integrins are cell–substrate adhesion molecules that provide the essential link between the actin cytoskeleton and the extracellular matrix during cell migration. We have analyzed αVβ3-integrin dynamics in migrating cells using a green fluorescent protein–tagged β3-integrin chain. At the cell front, adhesion sites containing αVβ3-integrin remain stationary, whereas at the rear of the cell they slide inward. The integrin fluorescence intensity within these different focal adhesions, and hence the relative integrin density, is directly related to their mobility. Integrin density is as much as threefold higher in sliding compared with stationary focal adhesions. High intracellular tension under the control of RhoA induced the formation of high-density contacts. Low-density adhesion sites were induced by Rac1 and low intracellular tension. Photobleaching experiments demonstrated a slow turnover of β3-integrins in low-density contacts, which may account for their stationary nature. In contrast, the fast β3-integrin turnover observed in high-density contacts suggests that their apparent sliding may be caused by a polarized renewal of focal contacts. Therefore, differential acto-myosin–dependent integrin turnover and focal adhesion densities may explain the mechanical and behavioral differences between cell adhesion sites formed at the front, and those that move in the retracting rear of migrating cells

Ecosystem Development in the Constructed Catchment “Chicken Creek”

Landscapes and ecosystems are complex systems with many feedback mechanisms acting between the various abiotic and biotic components. The knowledge about these interacting processes is mainly derived from mature ecosystems. The initial development of ecosystem complexity may involve state transitions following catastrophic shifts, disturbances, or transgression of thresholds. We propose a conceptual framework of feedback processes in early states of ecosystem development affected by spatiotemporal environmental drivers. To test this concept, we used 10-year time series of hydrological, biological, geomorphological, and soil data from the constructed catchment Chicken Creek.” The 6ha site was left to unrestricted development since 2005 and was intensively monitored. The data showed a very rapid development of the site with an increasing complexity and heterogeneity. In the first years, stochastic signals like the initial substrate conditions and external drivers like extreme weather events were the most important factors resulting in abiotic/abiotic feedback mechanisms shaping the morphology of the site and creating site diversity. Initial abiotic feedback mechanisms between water and substrate were soon followed by abiotic/biotic feedbacks between biological soil crusts, invading vegetation, geomorphology, and hydrology resulting in state transitions of catchment functioning

Ploidy level in the genus Leucanthemum correlates with resistance to a specialist herbivore

Polyploidy is considered to be a major source of genetic diversity in plants. Genome duplication has been shown repeatedly to be associated with changes in biotic interactions, but little is known about whether species traits such as herbivore resistance consistently change with increasing ploidy level among closely related plant species. We tested whether larval survival and performance of the specialist root- mining moth Dichrorampha aeratana are influenced by the ploidy level of plant species in the genus Leucanthemum by experimentally infesting 16 different taxa with ploidy levels ranging from diploid to dodecaploid. We found that survival of D. aeratana larvae consistently decreased with increasing ploidy level, irrespective of whether phylogenetic distance among taxa was taken into account or not. The mass of larvae and the proportion of adults emerging from last-instar larvae, however, did not consistently change with increasing ploidy level. Root biomass and dry matter content of the Leucanthemum taxa were neither correlated with ploidy level nor correlated with survival or mass of D. aeratana larvae. In summary, our results provide evidence that in the genus Leucanthemum, resistance to the specialist root herbivore D. aeratana consistently increases with increasing plant ploidy level, but it remains unclear which characteristics associated with polyploidy account for the higher herbivore resistance

Tropical cyclones and the ecohydrology of Australia's recent continental-scale drought

The Big Dry, a recent drought over southeast Australia, began around 1997 and continued until 2011. We show that between 2002-2010, instead of a localized drought, there was a continent-wide reduction in water storage, vegetation and rainfall, spanning the northwest to the southeast of Australia. Trends in water storage and vegetation were assessed using Gravity Recovery and Climate Experiment (GRACE) and Normalized Difference Vegetation Index (NDVI) data. Water storage and NDVI are shown to be significantly correlated across the continent and the greatest losses of water storage occurred over northwest Australia. The frequency of tropical cyclones over northwest Australia peaked just prior to the launch of the GRACE mission in 2002. Indeed, since 1981, decade-scale fluctuations in tropical cyclone numbers coincide with similar variation in rainfall and vegetation over northwest Australia. Rainfall and vegetation in southeast Australia trended oppositely to the northwest prior to 2001. Despite differences between the northwest and southeast droughts, there is reason to believe that continental droughts may occur when the respective climate drivers align

Ecosystems in transition: Interactions and feedbacks with an emphasis on the initial development

First paragraph: In this Special Issue of Biogeosciences on "Ecosystems in transition: Interactions and feedbacks with an emphasis on the initial development", we bring together research on ecosystems undergoing state transitions, including artificially created and naturally formed sites, most of them in an initial stage of development. State transitions of an ecosystem may occur either when a formerly stable system state is disturbed or when a developing system gradually achieves new functions during succession. Thus, state transitions of ecosystems are not necessarily restricted to a deterioration of ecosystems but can also be observed during initial ecosystem evolution.Output Type: Editoria