Mirage Torsion

Z_NxZ_M orbifold models admit the introduction of a discrete torsion phase. We find that models with discrete torsion have an alternative description in terms of torsionless models. More specifically, discrete torsion can be 'gauged away' by changing the shifts by lattice vectors. Similarly, a large class of the so-called generalized discrete torsion phases can be traded for changing the background fields (Wilson lines) by lattice vectors. We further observe that certain models with generalized discrete torsion are equivalent to torsionless models with the same gauge embedding but based on different compactification lattices. We also present a method of classifying heterotic Z_NxZ_M orbifolds.Comment: 26 pages, 3 figures, v2: matches version published in JHE

Probing the Galactic cosmic ray flux with submillimeter and gamma ray data

The study of Galactic diffuse $\gamma$ radiation combined with the knowledge of the distribution of the molecular hydrogen in the Galaxy offers a unique tool to probe the cosmic ray flux in the Galaxy. A methodology to study the level of the cosmic ray "sea" and to unveil target-accelerator systems in the Galaxy, which makes use of the data from the high resolution survey of the Galactic molecular clouds performed with the NANTEN telescope and of the data from gamma-ray instruments, has been developed. Some predictions concerning the level of the cosmic ray "sea" and the $\gamma$-ray emission close to cosmic ray sources for instruments such as Fermi and Cherenkov Telescope Array are presented.Comment: Proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronom

Orbital liquid in ferromagnetic manganites: The orbital Hubbard model for ege_g electrons

We have analyzed the symmetry properties and the ground state of an orbital Hubbard model with two orbital flavors, describing a partly filled spin-polarized $e_g$ band on a cubic lattice, as in ferromagnetic manganites. We demonstrate that the off-diagonal hopping responsible for transitions between $x^2-y^2$ and $3z^2-r^2$ orbitals, and the absence of SU(2) invariance in orbital space, have important implications. One finds that superexchange contributes in all orbital ordered states, the Nagaoka theorem does not apply, and the kinetic energy is much enhanced as compared with the spin case. Therefore, orbital ordered states are harder to stabilize in the Hartree-Fock approximation (HFA), and the onset of a uniform ferro-orbital polarization and antiferro-orbital instability are similar to each other, unlike in spin case. Next we formulate a cubic (gauge) invariant slave boson approach using the orbitals with complex coefficients. In the mean-field approximation it leads to the renormalization of the kinetic energy, and provides a reliable estimate for the ground state energy of the disordered state. Using this approach one finds that the HFA fails qualitatively in the regime of large Coulomb repulsion $U\to\infty$ -- the orbital order is unstable, and instead a strongly correlated orbital liquid with disordered orbitals is realized at any electron filling.Comment: 25 pages, 9 figure

Quantum Theory and Galois Fields

We discuss the motivation and main results of a quantum theory over a Galois field (GFQT). The goal of the paper is to describe main ideas of GFQT in a simplest possible way and to give clear and simple arguments that GFQT is a more natural quantum theory than the standard one. The paper has been prepared as a presentation to the ICSSUR' 2005 conference (Besancon, France, May 2-6, 2005).Comment: Latex, 24 pages, 1 figur

Geometric potential and transport in photonic topological crystals

We report on the experimental realization of an optical analogue of a quantum geometric potential for light wave packets constrained on thin dielectric guiding layers fabricated in silica by the femtosecond laser writing technology. We further demonstrate the optical version of a topological crystal, with the observation of Bloch oscillations and Zener tunneling of purely geometric nature

Upper Extremity Motor Learning among Individuals with Parkinson's Disease: A Meta-Analysis Evaluating Movement Time in Simple Tasks

Motor learning has been found to occur in the rehabilitation of individuals with Parkinson's disease (PD). Through repetitive structured practice of motor tasks, individuals show improved performance, confirming that motor learning has probably taken place. Although a number of studies have been completed evaluating motor learning in people with PD, the sample sizes were small and the improvements were variable. The purpose of this meta-analysis was to determine the ability of people with PD to learn motor tasks. Studies which measured movement time in upper extremity reaching tasks and met the inclusion criteria were included in the analysis. Results of the meta-analysis indicated that people with PD and neurologically healthy controls both demonstrated motor learning, characterized by a decrease in movement time during upper extremity movements. Movement time improvements were greater in the control group than in individuals with PD. These results support the findings that the practice of upper extremity reaching tasks is beneficial in reducing movement time in persons with PD and has important implications for rehabilitation

The Emergence of Gated Communities in Ghana and their Implications on Urban Planning and Management

Over the past few decades, gated communities have emerged as global commodity increasingly gaining patronage. In Sub-Sahara Africa, the city of Accra is fast recording the emergence of these communities. The research therefore examined the implications of the rising phenomenon in urban planning and management. By adopting a mixture of snow ball, simple random and purposive sampling and a face to face interview technique, the research accessed empirical data from planning institutions and households selected from three gated communities in the capital city of Accra. It was found that, gated communities in the capital have relatively good infrastructural facilities and services, the provision of which the real estate developers played a major role. However, a spatial policy gap on gated communities was identified in addition to missing legislative framework and low level of awareness on the part of planning institutions regarding the existence of some gated communities in the capital. In ensuring effective planning and management of gated communities in the urban arena as well as situating their occurrence within a broader spatial and socio-economic development of the country, the research concludes that, formulation of spatial policy and legislative framework and strengthening of planning institutions are requisite. Keywords: gated communities, urban planning, urban managemen

Sistem Automasi Proses Produksi Minuman Dengan Sistem SCADA Menggunakan PLC

Industries need production processes that can be operated continually from one process to another without a lot of human energy resources. The solution of the problem is using an automation system which can be worked and operated from one central operator. SCADA with PLC can be used in many industrial processes because it can answer all the problems in controlling industrial application automatically. This paper describe how to make a design of simulation plant for beverages production process. The plant will use : pumps, mixer, valves, and heater. This plant will be operated by PLC Omron C-200 HS which is connected to SCADA Intouch, Wonderware Production. The comunication between PLC Omron and SCADA Intouch use Host Link RS 232c with I/O Servers program. The result from the simulation plant design for the minimum power shaft pump is 6.788 Watt. The mixer need a motor with speed 114 rpm. And the heater need 1000 Watt at 01:44:21.64. While the minimum valve design is needed to hold the fluids pressure until 106,4096 KPa