QCDGPU: open-source package for Monte Carlo lattice simulations on OpenCL-compatible multi-GPU systems

The multi-GPU open-source package QCDGPU for lattice Monte Carlo simulations of pure SU(N) gluodynamics in external magnetic field at finite temperature and O(N) model is developed. The code is implemented in OpenCL, tested on AMD and NVIDIA GPUs, AMD and Intel CPUs and may run on other OpenCL-compatible devices. The package contains minimal external library dependencies and is OS platform-independent. It is optimized for heterogeneous computing due to the possibility of dividing the lattice into non-equivalent parts to hide the difference in performances of the devices used. QCDGPU has client-server part for distributed simulations. The package is designed to produce lattice gauge configurations as well as to analyze previously generated ones. QCDGPU may be executed in fault-tolerant mode. Monte Carlo procedure core is based on PRNGCL library for pseudo-random numbers generation on OpenCL-compatible devices, which contains several most popular pseudo-random number generators.Comment: Presented at the Third International Conference "High Performance Computing" (HPC-UA 2013), Kyiv, Ukraine; 9 pages, 2 figure

The effect of mesh shelters and nitrogen fertilzer on growth for bigtooth aspen wildlife plantings

Paper presented at the 13th North American Agroforesty Conference, which was held June 19-21, 2013 in Charlottetown, Prince Edward Island, Canada.In Poppy, L., Kort, J., Schroeder, B., Pollock, T., and Soolanayakanahally, R., eds. Agroforestry: Innovations in Agriculture. Proceedings, 13th North American Agroforestry Conference, Charlottetown, Prince Edward Island, Canada, June 19-21, 2013.Bigtooth aspen (Populus grandidentata) is a good species for use in conservation plantings in the agricultural landscape of Central Wisconsin. The buds and twigs are utilized as forage by a range of species in winter. The species is easy to manage with coppice and the resulting pulpwood finds a ready market. Early establishment of plantings can, however, be plagued by excessive browse damage. Our objective was to determine if nitrogen fertilization, poultry mesh tree shelters or a combination of both would increase aspen seedling growth rate. We planted 8 split plots of 12 bigtooth aspen seedlings (1-0 stock) (96 total seedlings). Four of the plots were fertilized with polymer coated urea at a rate of 90 Kg N per hectare and four were controls. Half of the trees in each split-plot were caged with 5 foot tall poultry mesh shelters (5 inch diameter) and half were uncaged. The poultry mesh shelters increased seedling growth. Overall, sheltered seedlings averaged 91 cm while unsheltered averaged 51 cm, with or without fertilization. However, the combination of both shelters and fertilization (107 cm) had a much greater impact than either fertilizer alone (54 cm) or shelter alone (75 cm) or the control (47 cm). At this point, all seedlings are still within the browse height of deer; however, it appears that the impact of fertilization alone is not sufficient to help the trees outgrow deer browsing although the addition of fertilizer with the use of tree shelters results in significantly increased growth.Mike Demchik (1) and Emily Demchik (2) ; 1. University of Wisconsin Stevens Point, 800 Reserve Street, Stevens Point, WI, 54481 USA. 2. Oak Openings Farm, 8438 14th Road, Almond, WI 54909, USA.Includes bibliographical references

The spontaneous generation of magnetic fields at high temperature in a supersymmetric theory

The spontaneous generation of magnetic and chromomagnetic fields at high temperature in the minimal supersymmetric standard model (MSSM) is investigated. The consistent effective potential including the one-loop and the daisy diagrams of all bosons and fermions is calculated and the magnetization of the vacuum is observed. The mixing of the generated fields due to the quark and s-quark loop diagrams and the role of superpartners are studied in detail. It is found that the contribution of these diagrams increases the magnetic and chromomagnetic field strengths as compared with the case of a separate generation of fields. The magnetized vacuum state is found to be stable due to the magnetic masses of gauge fields included in the daisy diagrams. Applications of the results obtained are discussed. A comparison with the standard model case is done.Comment: 14 pages, 2 figures, 3 table

Model-independent search for the Abelian Z' boson in the Bhabha process

Model-independent observables to pick out the Abelian Z' signal in the Bhabha process are introduced at energies >= 200 GeV. They measure separately the Z'-induced vector and axial-vector four-fermion contact couplings. The analysis of the LEP2 data constrains the value of the Z'-induced vector four-fermion coupling at the 2-sigma confidence level that corresponds to the Abelian Z' boson with the mass of order 1 TeV.Comment: 7 pages, 5 figures, uses RevTeX4. The text of the paper is completely rewritte