107 research outputs found
Convergence of quantum random walks with decoherence
In this paper, we study the discrete-time quantum random walks on a line
subject to decoherence. The convergence of the rescaled position probability
distribution depends mainly on the spectrum of the superoperator
. We show that if 1 is an eigenvalue of the superoperator
with multiplicity one and there is no other eigenvalue whose modulus equals to
1, then converges to a convex combination of
normal distributions. In terms of position space, the rescaled probability mass
function , , converges in
distribution to a continuous convex combination of normal distributions. We
give an necessary and sufficient condition for a U(2) decoherent quantum walk
that satisfies the eigenvalue conditions.
We also give a complete description of the behavior of quantum walks whose
eigenvalues do not satisfy these assumptions. Specific examples such as the
Hadamard walk, walks under real and complex rotations are illustrated. For the
O(2) quantum random walks, an explicit formula is provided for the scaling
limit of and their moments. We also obtain exact critical exponents
for their moments at the critical point and show universality classes with
respect to these critical exponents
Tuberculosis infection among homeless persons and caregivers in a high-tuberculosis-prevalence area in Japan: a cross-sectional study
<p>Abstract</p> <p>Background</p> <p>Tuberculosis (TB) is a major public health problem. The Airin district of Osaka City has a large population of homeless persons and caregivers and is estimated to be the largest TB-endemic area in the intermediate-prevalence country, Japan. However, there have been few studies of homeless persons and caregivers. The objective of this study is to detect active TB and to assess the prevalence and risk factors for latent TB infection among homeless persons and caregivers.</p> <p>Methods</p> <p>We conducted a cross-sectional study for screening TB infection (active and latent TB infections) using questionnaire, chest X-ray (CXR), newly available assay for latent TB infection (QuantiFERON-TB Gold In-Tube; QFT) and clinical evaluation by physicians at the Osaka Socio-Medical Center Hospital between July 2007 and March 2008. Homeless persons and caregivers, aged 30-74 years old, who had not received CXR examination within one year, were recruited. As for risk factors of latent TB infection, the odds ratios (OR) and 95% confidence intervals (95% CI) for QFT-positivity were calculated using logistic regression model.</p> <p>Results</p> <p>Complete responses were available from 436 individuals (263 homeless persons and 173 caregivers). Four active TB cases (1.5%) among homeless persons were found, while there were no cases among caregivers. Out of these four, three had positive QFT results. One hundred and thirty-three (50.6%) homeless persons and 42 (24.3%) caregivers had positive QFT results. In multivariate analysis, QFT-positivity was independently associated with a long time spent in the Airin district: â„10 years versus <10 years for homeless (OR = 2.53; 95% CI, 1.39-4.61) and for caregivers (OR = 2.32; 95% CI, 1.05-5.13), and the past exposure to TB patients for caregivers (OR = 3.21; 95% CI, 1.30-7.91) but not for homeless persons (OR = 1.51; 95% CI, 0.71-3.21).</p> <p>Conclusions</p> <p>Although no active TB was found for caregivers, one-quarter of them had latent TB infection. In addition to homeless persons, caregivers need examinations for latent TB infection as well as active TB and careful follow-up, especially when they have spent a long time in a TB-endemic area and/or have been exposed to TB patients.</p
The adaptation of a CTN-1 rabies virus strain to high-titered growth in chick embryo cells for vaccine development
Degradation of haloaromatic compounds
An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level
Pyrroloquinoline Quinone-Dependent Cytochrome Reduction in Polyvinyl Alcohol-Degrading Pseudomonas
Angular Dependence on X-ray Image of Lesions at Articular Cartilage Depicted by X-ray Dark-Field Imaging
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