Multi-Architecture Monte-Carlo (MC) Simulation of Soft Coarse-Grained Polymeric Materials: SOft coarse grained Monte-carlo Acceleration (SOMA)

Multi-component polymer systems are important for the development of new materials because of their ability to phase-separate or self-assemble into nano-structures. The Single-Chain-in-Mean-Field (SCMF) algorithm in conjunction with a soft, coarse-grained polymer model is an established technique to investigate these soft-matter systems. Here we present an im- plementation of this method: SOft coarse grained Monte-carlo Accelera- tion (SOMA). It is suitable to simulate large system sizes with up to billions of particles, yet versatile enough to study properties of different kinds of molecular architectures and interactions. We achieve efficiency of the simulations commissioning accelerators like GPUs on both workstations as well as supercomputers. The implementa- tion remains flexible and maintainable because of the implementation of the scientific programming language enhanced by OpenACC pragmas for the accelerators. We present implementation details and features of the program package, investigate the scalability of our implementation SOMA, and discuss two applications, which cover system sizes that are difficult to reach with other, common particle-based simulation methods

On the nature of Thermal Diffusion in binary Lennard-Jones liquids

The aim of this study is to understand deeper the thermal diffusion transport process (Ludwig-Soret effect) at the microscopic level. For that purpose, the recently developed reverse nonequilibrium molecular dynamics method was used to calculate Soret coefficients of various systems in a systematic fashion. We studied binary Lennard-Jones (LJ) fluids near the triple point (of one of the components) in which we separately changed the ratio of one of the LJ parameters mass, atomic diameter and interaction strength while keeping all other parameters fixed and identical. We observed that the magnitude of the Soret coefficient depends on all three ratios. Concerning its sign we found that heavier species, smaller species and species with higher interaction strengths tend to accumulate in the cold region whereas the other ones (lighter, bigger or weaker bound) migrate to the hot region of our simulation cell. Additionally, the superposition of the influence of the various parameters was investigated as well as more realistic mixtures. We found that in the experimentally relevant parameter range the contributions are nearly additive and that the mass ratio often is the dominating factor.Comment: 27 pages, 9 figures, submitted to J. Chem. Phy

Synthesis and hydrolysis of auxins and their conjugates with different side-chain lengths: are all products active auxins?

Plants need hormone substances to regulate a plethora of responses during their life cycle. One major hormone class is called auxin, which is involved in many developmental processes. Besides the major auxin indole-3-acetic acid, there are other auxin-like molecules present in some, but not in all plants, an example would be chlorinated IAA in legumes. Among these are also the auxins with longer chains, indole-3-propionic acid and indole-3-butyric acid. The auxin-dependent growth response is dependent on the concentration of the compound. While lower concentrations are mainly growth promoting, high concentrations are actually inhibiting some developmental processes. Therefore, tight control of the auxin concentration is essential for proper growth and development. This can be achieved by altering the amount of active auxin via transport, biosynthesis, degradation or reversible conjugation to small molecules. In addition, plants use auxin during their interaction with the environment, for example during abiotic stresses such as salt, temperature or water stress to adapt the growth responses specifically. Furthermore, auxin is involved in the development of plant disease symptoms, such as tumor growth or aberrant tissue formation. However, together with other plant hormones such as salicylic acid auxin can also modulate disease progression or resistance in different plant – microbe combinations. </p

AUTOMATING PERIODIC ROLE-CHECKS A TOOL-BASED APPROACH

The use of roles in Identity Management has proven to be a solution for reorganising and securing the access structures of organisations. One critical challenge companies face after they implemented roles is the maintenance of the role system itself. This includes sophisticated duties like periodically verifying the valid roles. We argue that due to the high complexity, periodic rolechecks need to be automated. However, as a result of lacking theoretical foundation, no approaches to leverage the level automation have been published so far. In this work we develop a catalogue of use cases that affect the role definitions within an organisation. We propose checkROLE, a tool for automated role-checking on basis of the defined use case catalogue

Chlorinated auxins–how does Arabidopsis thaliana deal with them?

Plant hormones have various functions in plants and play crucial roles in all developmental and differentiation stages. Auxins constitute one of the most important groups with the major representative indole-3-acetic acid (IAA). A halogenated derivate of IAA, 4-chloro-indole-3-acetic acid (4-Cl-IAA), has previously been identified in Pisum sativum and other legumes. While the enzymes responsible for the halogenation of compounds in bacteria and fungi are well studied, the metabolic pathways leading to the production of 4-Cl-IAA in plants, especially the halogenating reaction, are still unknown. Therefore, bacterial flavin-dependent tryptophan-halogenase genes were transformed into the model organism Arabidopsis thaliana. The type of chlorinated indole derivatives that could be expected was determined by incubating wild type A. thaliana with different Cl-tryptophan derivatives. We showed that, in addition to chlorinated IAA, chlorinated IAA conjugates were synthesized. Concomitantly, we found that an auxin conjugate synthetase (GH3.3 protein) from A. thaliana was able to convert chlorinated IAAs to amino acid conjugates in vitro. In addition, we showed that the production of halogenated tryptophan (Trp), indole-3-acetonitrile (IAN) and IAA is possible in transgenic A. thaliana in planta with the help of the bacterial halogenating enzymes. Furthermore, it was investigated if there is an effect (i) of exogenously applied Cl-IAA and Cl-Trp and (ii) of endogenously chlorinated substances on the growth phenotype of the plants

Has gambling changed after major amendments of gambling regulations in Germany? A propensity score analysis

Aims: This study examined changes in general population gambling in the light of two major amendments of the German gambling regulation, the Fifth Amendment of the German Gambling Ordinance (AGO) for commercial amusement machines with prizes (AWP) and the State Treaty on Gambling (STG) for gambling activities subject to the state monopoly. Methods: Applying cross-sectional data from the 2006 and 2009 Epidemiological Survey of Substance Abuse (ESA), propensity-score-matched samples of 7,970 subjects and 3,624 12-month gamblers aged 18–64 years were used for analyses. Logistic regression was employed to examine changes in gambling controlling for possible confounding variables. Results: Overall participation in state gambling activities, participation in lotto as well as TV lottery decreased and gambling on Internet card games increased. No changes were found for any other gambling activity, 12-month prevalence of any gambling and pathological gambling. While weekly gambling declined, overall multiple gambling increased. Effects were similar in the total sample and among current gamblers. Conclusions: Prohibiting specific gambling activities, e.g., Internet gambling, seem to be insufficient approaches to change gambling behavior. Supply reduction might need to be enhanced by changes in game characteristics and implementation of early intervention measures. However, long-term consequences are uncertain and further monitoring is needed