Two-dimensional gases of generalized statistics in a uniform magnetic field

We study the low temperature properties of two-dimensional ideal gases of generalized statistics in a uniform magnetic field. The generalized statistics considered here are the parafermion statistics and the exclusion statistics. Similarity in the behaviours of the parafermion gas of finite order $p$ and the gas with exclusion coefficient $g=1/p$ at very low temperatures is noted. These two systems become exactly equivalent at $T=0$. Qumtum Hall effect with these particles as charge carriers is briefly discussed.Comment: Latex file, 14 pages, 5 figures available on reques

Spinor Bose Condensates in Optical Traps

In an optical trap, the ground state of spin-1 Bosons such as $^{23}$Na, $^{39}$K, and $^{87}$Rb can be either a ferromagnetic or a "polar" state, depending on the scattering lengths in different angular momentum channel. The collective modes of these states have very different spin character and spatial distributions. While ordinary vortices are stable in the polar state, only those with unit circulation are stable in the ferromagnetic state. The ferromagnetic state also has coreless (or Skyrmion) vortices like those of superfluid $^{3}$He-A. Current estimates of scattering lengths suggest that the ground states of $^{23}$Na and $^{87}$Rb condensate are a polar state and a ferromagnetic state respectively.Comment: 11 pages, no figures. email : [email protected]

Influence of high gas production during thermophilic anaerobic digestion in pilot-scale and lab-scale reactors on survival of the thermotolerant pathogens Clostridium perfringens and Campylobacter jejuni in piggery wastewater

Safe reuse of animal wastes to capture energy and nutrients, through anaerobic digestion processes, is becoming an increasingly desirable solution to environmental pollution. Pathogen decay is the most important safety consideration and is in general, improved at elevated temperatures and longer hydraulic residence times. During routine sampling to assess pathogen decay in thermophilic digestion, an inversely proportional relationship between levels of Clostridium perfringens and gas production was observed. Further samples were collected from pilot-scale, bench-scale thermophilic reactors and batch scale vials to assess whether gas production (predominantly methane) could be a useful indicator of decay of the thermotolerant pathogens C. perfringens and Campylobacter jejuni. Pathogen levels did appear to be lower where gas production and levels of methanogens were higher. This was evident at each operating temperature (50, 57, 65 °C) in the pilot-scale thermophilic digesters, although higher temperatures also reduced the numbers of pathogens detected. When methane production was higher, either when feed rate was increased, or pH was lowered from 8.2 (piggery wastewater) to 6.5, lower numbers of pathogens were detected. Although a number of related factors are known to influence the amount and rate of methane production, it may be a useful indicator of the removal of the pathogens C. perfringens and C. jejuni

Development of aircraft brake materials

The requirements of brake materials were outlined and a survey made to select materials to meet the needs of high temperature brakes. A number of metals and ceramic materials were selected and evaluated in sliding tests which simulated aircraft braking. Nickel, molybdenum tungsten, Zr02, high temperature cements and carbons were tested. Additives were then incorporated into these materials to optimize their wear or strength behavior with particular emphasis on nickel and molybdenum base materials and a high temperature potassium silicate cement. Optimum materials were developed which improved wear behavior over conventional brake materials in the simulated test. The best materials are a nickel, aluminum oxide, lead tungstate composition containing graphite or molybdenum disulphite; a molybdenum base material containing LPA100 (an intermetallic compound of cobalt, molybdenum, and silicon); and a carbon material (P5)

Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed

Boundary Condition of Polyelectrolyte Adsorption

The modification of the boundary condition for polyelectrolyte adsorption on charged surface with short-ranged interaction is investigated under two regimes. For weakly charged Gaussian polymer in which the short-ranged attraction dominates, the boundary condition is the same as that of the neutral polymer adsorption. For highly charged polymer (compressed state) in which the electrostatic interaction dominates, the linear relationship (electrostatic boundary condition) between the surface monomer density and the surface charge density needs to be modified.Comment: 4 page

A Tidal Flare Candidate in Abell 1795

As part of our ongoing archival X-ray survey of galaxy clusters for tidal flares, we present evidence of an X-ray transient source within 1 arcmin of the core of Abell 1795. The extreme variability (a factor of nearly 50), luminosity (> 2 x 10^42 erg s^{-1}), long duration (> 5 years) and supersoft X-ray spectrum (< 0.1 keV) are characteristic signatures of a stellar tidal disruption event according to theoretical predictions and to existing X-ray observations, implying a massive >~10^5 M_sun black hole at the centre of that galaxy. The large number of X-ray source counts (~700) and long temporal baseline (~12 years with Chandra and XMM-Newton) make this one of the best-sampled examples of any tidal flare candidate to date. The transient may be the same EUV source originally found contaminating the diffuse ICM observations of Bowyer et al. (1999), which would make it the only tidal flare candidate with reported EUV observations and implies an early source luminosity 1-2 orders of magnitude greater. If the host galaxy is a cluster member then it must be a dwarf galaxy, an order of magnitude less massive than the quiescent galaxy Henize 2-10 which hosts a massive black hole that is difficult to reconcile with its low mass. The unusual faintness of the host galaxy may be explained by tidal stripping in the cluster core.Comment: Accepted by MNRAS 2013 July 23. 27 pages, 10 figure

Google matrix of the citation network of Physical Review

We study the statistical properties of spectrum and eigenstates of the Google matrix of the citation network of Physical Review for the period 1893 - 2009. The main fraction of complex eigenvalues with largest modulus is determined numerically by different methods based on high precision computations with up to $p=16384$ binary digits that allows to resolve hard numerical problems for small eigenvalues. The nearly nilpotent matrix structure allows to obtain a semi-analytical computation of eigenvalues. We find that the spectrum is characterized by the fractal Weyl law with a fractal dimension $d_f \approx 1$. It is found that the majority of eigenvectors are located in a localized phase. The statistical distribution of articles in the PageRank-CheiRank plane is established providing a better understanding of information flows on the network. The concept of ImpactRank is proposed to determine an influence domain of a given article. We also discuss the properties of random matrix models of Perron-Frobenius operators.Comment: 25 pages. 17 figures. Published in Phys. Rev.