4,516 research outputs found
Hawking Radiation of Black p-Branes from Gravitational Anomaly
We investigate the Hawking radiation of black -branes of superstring
theories using the method of anomaly cancelation, specially, we use the method
of [S. Iso, H. Umetsu and F. Wilczek, {\sl Phys. Rev. Lett.} {\bf 96}, 151302
(2006); {\sl Phys. Rev. D} {\bf 74}, 044017 (2006)]. The metrics of black
-branes are spherically symmetric, but not the Schwarzschild type. In order
to simplify the calculation, we first make a coordinate transformation to
transform the metric to the Schwarzschild type. Then we calculate its
energy-momentum flux from the method of anomaly cancelation of the above
mentioned references. The obtained energy-momentum flux is equal to a black
body radiation, the thermodynamic temperature of the radiation is equal to its
Hawking temperature. And we find that the results are not changed for the
original non-Schwarzschild type spherically symmetric metric.Comment: 19 pages Latex, some mistakes correcte
Aspects of Confinement and Chiral Dynamics in 2-d QED at Finite Temperature
We evaluate the Polyakov loop and string tension at zero and finite
temperature in Using bozonization the problem is reduced to solving
the Schr\"odinger equation with a particular potential determined by the ground
state. In the presence of two sources of opposite charges the vacuum angle
parameter changes by , independent of the number of
flavors. This, in turn, alters the chiral condensate. Particularly, in the one
flavor case through a simple computer algorithm, we explore the chiral dynamics
of a heavy fermion.Comment: 4 pages, 2 ps files, uses sprocl.sty. To appear in Proceedings of
DPF96 (August, Minnesota
Confinement and Chiral Dynamics in the Multi-flavor Schwinger Model
Two-dimensional QED with flavor fermions is solved at zero and finite
temperature with arbitrary fermion masses to explore QCD physics such as chiral
condensate and string tension. The problem is reduced to solving a
Schr\"odinger equation for degrees of freedom with a specific potential
determined by the ground state of the Schr\"odinger problem itself.Comment: 9 pages. 3 ps files and sprocl.sty attached. To appear in the
Proceedings of the QCD 96 workshop (March, Minnesota
Standardisation of magnetic nanoparticles in liquid suspension
Suspensions of magnetic nanoparticles offer diverse opportunities for technology innovation, spanning a large number of industry sectors from imaging and actuation based applications in biomedicine and biotechnology, through large-scale environmental remediation uses such as water purification, to engineering-based applications such as position-controlled lubricants and soaps. Continuous advances in their manufacture have produced an ever-growing range of products, each with their own unique properties. At the same time, the characterisation of magnetic nanoparticles is often complex, and expert knowledge is needed to correctly interpret the measurement data. In many cases, the stringent requirements of the end-user technologies dictate that magnetic nanoparticle products should be clearly defined, well characterised, consistent and safe; or to put it another way—standardised. The aims of this document are to outline the concepts and terminology necessary for discussion of magnetic nanoparticles, to examine the current state-of-the-art in characterisation methods necessary for the most prominent applications of magnetic nanoparticle suspensions, to suggest a possible structure for the future development of standardisation within the field, and to identify areas and topics which deserve to be the focus of future work items. We discuss potential roadmaps for the future standardisation of this developing industry, and the likely challenges to be encountered along the way
Anomalies, Horizons and Hawking radiation
Hawking radiation is obtained from the Reissner-Nordstr\"{o}m blackhole with
a global monopole and the Garfinkle-Horowitz-Strominger blackhole falling in
the class of the most general spherically symmetric blackholes
, using only chiral anomaly near the event horizon and
covariant boundary condition at the event horizon. The approach differs from
the anomaly cancellation approach since apart from the covariant boundary
condition, the chiral anomaly near the horizon is the only input to derive the
Hawking flux.Comment: minor corrections made, To appear in Euro. Phys. Letter
Quantitative estimation of sampling uncertainties for mycotoxins in cereal shipments
Many countries receive shipments of bulk cereals from primary producers. There is a volume of work that is ongoing that seeks to arrive at appropriate standards for the quality of the shipments and the means to assess the shipments as they are out-loaded. Of concern are mycotoxin and heavy metal levels, pesticide and herbicide residue levels, and contamination by genetically modified organisms (GMOs). As the ability to quantify these contaminants improves through improved analytical techniques, the sampling methodologies applied to the shipments must also keep pace to ensure that the uncertainties attached to the sampling procedures do not overwhelm the analytical uncertainties. There is a need to understand and quantify sampling uncertainties under varying conditions of contamination. The analysis required is statistical and is challenging as the nature of the distribution of contaminants within a shipment is not well understood; very limited data exist. Limited work has been undertaken to quantify the variability of the contaminant concentrations in the flow of grain coming from a ship and the impact that this has on the variance of sampling. Relatively recent work by Paoletti et al. in 2006 [Paoletti C, Heissenberger A, Mazzara M, Larcher S, Grazioli E, Corbisier P, Hess N, Berben G, Lubeck PS, De Loose M, et al. 2006. Kernel lot distribution assessment (KeLDA): a study on the distribution of GMO in large soybean shipments. Eur Food Res Tech. 224:129–139] provides some insight into the variation in GMO concentrations in soybeans on cargo out-turn. Paoletti et al. analysed the data using correlogram analysis with the objective of quantifying the sampling uncertainty (variance) that attaches to the final cargo analysis, but this is only one possible means of quantifying sampling uncertainty. It is possible that in many cases the levels of contamination passing the sampler on out-loading are essentially random, negating the value of variographic quantitation of the sampling variance. GMOs and mycotoxins appear to have a highly heterogeneous distribution in a cargo depending on how the ship was loaded (the grain may have come from more than one terminal and set of storage silos) and mycotoxin growth may have occurred in transit. This paper examines a statistical model based on random contamination that can be used to calculate the sampling uncertainty arising from primary sampling of a cargo; it deals with what is thought to be a worst-case scenario. The determination of the sampling variance is treated both analytically and by Monte Carlo simulation. The latter approach provides the entire sampling distribution and not just the sampling variance. The sampling procedure is based on rules provided by the Canadian Grain Commission (CGC) and the levels of contamination considered are those relating to allowable levels of ochratoxin A (OTA) in wheat. The results of the calculations indicate that at a loading rate of 1000 tonnes h-1, primary sample increment masses of 10.6 kg, a 2000-tonne lot and a primary composite sample mass of 1900 kg, the relative standard deviation (RSD) is about 1.05 (105%) and the distribution of the mycotoxin (MT) level in the primary composite samples is highly skewed. This result applies to a mean MT level of 2 ng g-1. The rate of false-negative results under these conditions is estimated to be 16.2%. The corresponding contamination is based on initial average concentrations of MT of 4000 ng g-1 within average spherical volumes of 0.3m diameter, which are then diluted by a factor of 2 each time they pass through a handling stage; four stages of handling are assumed. The Monte Carlo calculations allow for variation in the initial volume of the MT-bearing grain, the average concentration and the dilution factor. The Monte Carlo studies seek to show the effect of variation in the sampling frequency while maintaining a primary composite sample mass of 1900 kg. The overall results are presented in terms of operational characteristic curves that relate only to the sampling uncertainties in the primary sampling of the grain. It is concluded that cross-stream sampling is intrinsically unsuited to sampling for mycotoxins and that better sampling methods and equipment are needed to control sampling uncertainties. At the same time, it is shown that some combination of crosscutting sampling conditions may, for a given shipment mass and MT content, yield acceptable sampling performance
Tobacco Control Measures to Reduce Socioeconomic Inequality in Smoking: The Necessity, Time-Course Perspective, and Future Implications
Previous systematic reviews of population-level tobacco control interventions and their effects on smoking inequality by socioeconomic factors concluded that tobacco taxation reduce smoking inequality by income (although this is not consistent for other socioeconomic factors, such as education). Inconsistent results have been reported for socioeconomic differences, especially for other tobacco control measures, such as smoke-free policies and anti-tobacco media campaigns. To understand smoking inequality itself and to develop strategies to reduce smoking inequality, knowledge of the underlying principles or mechanisms of the inequality over a long time-course may be important. For example, the inverse equity hypothesis recognizes that inequality may evolve in stages. New population-based interventions are initially primarily accessed by the affluent and well-educated, so there is an initial increase in socioeconomic inequality (early stage). These inequalities narrow when the deprived population can access the intervention after the affluent have gained maximum benefit (late stage). Following this hypothesis, all tobacco control measures may have the potential to reduce smoking inequality, if they continue for a long term, covering and reaching all socioeconomic subgroups. Re-evaluation of the impact of the interventions on smoking inequality using a long time-course perspective may lead to a favorable next step in equity effectiveness. Tackling socioeconomic inequality in smoking may be a key public health target for the reduction of inequality in health
Chern-Simons matrix model: coherent states and relation to Laughlin wavefunctions
Using a coherent state representation we derive many-body probability
distributions and wavefunctions for the Chern-Simons matrix model proposed by
Polychronakos and compare them to the Laughlin ones. We analyze two different
coherent state representations, corresponding to different choices for electron
coordinate bases. In both cases we find that the resulting probability
distributions do not quite agree with the Laughlin ones. There is agreement on
the long distance behavior, but the short distance behavior is different.Comment: 15 pages, LaTeX; one reference added, abstract and section 5
expanded, typos correcte
Resonant Leptogenesis in the Minimal B-L Extended Standard Model at TeV
We investigate the resonant leptogenesis scenario in the minimal B-L extended
standard model(SM) with the B-L symmetry breaking at the TeV scale. Through
detailed analysis of the Boltzmann equations, we show how much the resultant
baryon asymmetry via leptogenesis is enhanced or suppressed, depending on the
model parameters, in particular, the neutrino Dirac Yukawa couplings and the
TeV-scale Majorana masses of heavy degenerate neutrinos. In order to consider a
realistic case, we impose a simple ansatz for the model parameters and analyze
the neutrino oscillation parameters and the baryon asymmetry via leptogenesis
as a function of only a single CP-phase. We find that for a fixed CP-phase all
neutrino oscillation data and the observed baryon asymmetry of the present
universe can be simultaneously reproduced.Comment: 25 pages, 15 figures, version to be published in Phys. Rev.
Smooth Paths on Three Dimensional Lattice
A particular class of random walks with a spin factor on a three dimensional
cubic lattice is studied. This three dimensional random walk model is a simple
generalization of random walk for the two dimensional Ising model. All critical
diffusion constants and associated critical exponents are calculated. Continuum
field theories such as Klein-Gordon, Dirac and massive Chern-Simons theories
are constructed near several critical points.Comment: 7 pages,NUP-A-94-
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