51,683 research outputs found
Fermionic Quasiparticles in QCD at High Baryon Density
We study fermionic quasi-particles in QCD at very high baryon density. In the
normal quark matter phase unscreened magnetic gluon exchanges lead to non-Fermi
liquid behavior. Non-Fermi liquid effects manifest themselves in low energy
Green functions that depend on logarithms and fractional powers of energy. In
the superfluid phase there is an energy gap for fermionic excitations. Quark
mass effects can cause the energy gap to vanish. Gapless fermions in the color
flavor locked phase cause an instability towards a state with a non-zero
supercurrent.Comment: 4 pages, to appear in the proceedings of Quark Matter 2005, Budapest,
Aug 4-
Methodical Problems in Organic Farming Research
Workshop presentation with particular focus on values, transferability and praxis relevance of organic farming research. Examples from agricultural engineering lead to the conclusion, that prototype farming, goal oriented project management, participative decision making and funding, coaching of co-operation, and coaching of conflict management may enhance long term, holistic and interdisciplinary research
Color superconductivity: Continuity of quark and hadron matter, the role of the strange quark mass, and perturbative results
We summarize some recent results on the structure of QCD at very high baryon
density.Comment: 4 pages, to appear in the proceedings of Quark Matter 9
Technique of pneumatic pest control – analyses and a new device
Pest control in organic production of berries, potatoes and vegetables usually employs spreading technique of registered phytopharmaceutical agents. This technique may be supported or even replaced by pneumatic pest control. Pneumatic pest control means suction of pest using a vacuum device similar to a home vacuum cleaner. Up to now there is no evaluation of pneumatic pest control available from an agricultural engineering point of view. This paper concerns the following questions: Which techniques of pneumatic pest control are available and how may these techniques be improved in terms of technical and physical parameters? Based on the answers a new device design is presented
Particle algorithms for optimization on binary spaces
We discuss a unified approach to stochastic optimization of pseudo-Boolean
objective functions based on particle methods, including the cross-entropy
method and simulated annealing as special cases. We point out the need for
auxiliary sampling distributions, that is parametric families on binary spaces,
which are able to reproduce complex dependency structures, and illustrate their
usefulness in our numerical experiments. We provide numerical evidence that
particle-driven optimization algorithms based on parametric families yield
superior results on strongly multi-modal optimization problems while local
search heuristics outperform them on easier problems
New particles in strong fields?
The recent search for new particles in the MeV mass range is reviewed. The most relevant experiments, most notably the GSI positron experiments, are described and their results are combined to restrict the properties of the hypothetical particles. The theoretical analyses of these and a large number of other experiments are presented in detail. Finally some special candidates for new particles such as the axion and localised complex vacuum excitations are discussed. The author discusses a number of ideas and suggestions which merit further investigation. With respect to the GSI experiments it is concluded that it is very unlikely that the observed e^+-e^- coincidences indicate the existence of new particles
The role of engineering in organic farming – case energy crops
Energy self-reliance and a closed nutrient cycle are basic principles of organic farming ever since. Engineering sciences methods in energy accounting may support efforts to introduce these principles into praxis. A method to calculate efficiency of energy crop production including sun energy, direct and indirect energy for cultivation, processing, and conversion into fuel is demonstrated using rape and derived fuels as an example. Every production and conversion step is a process and calculated separately. The overall efficiency includes energy input and output of all processes. The process effi-ciency of rape cultivation reaches in Finland up to 1100%. However, the overall en-ergy efficiency of rape methyl ester (RME) is 1 to 2 ‰ only. The production of biogas from manure of dairy fed by rape meal results in a process energy efficiency of 33 to 41%, but the overall energy efficiency of RME and biogas together is only 1.2 to 2.5 ‰. In contrast, thermal or photovoltaic solar collectors improve overall efficiency 1 to 3 orders of magnitude compared to fuel production from rape, because the process efficiency of photosynthesis attains about 0.6% whereas solar collector’s efficiency reaches about 90%. However, for the time being solar energy based techniques are more expensive than the use of fossil energy sources since environmental benefits in terms of GHG mitigation, reduction of nutrient run off and use of renewable energy do not create cash income in both organic and main stream production. This and the low photosynthesis efficiency in Finland encourage bio-refinery enterprises to purchase energy crop produce for fuel production from the tropics. Mineral fertilisers as well as genetic modification increase the technical efficiency of photosynthesis. Thus, envi-ronmental pollution of mainstream agriculture is exported to developing countries in the tropics
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