The application of molecular techniques for the rapid and sensitive detection of gastrointestinal pathogens directly in food

Conventional microbiological methods are slow, labour intensive and are unable to meet the demands for rapid food testing. Molecular methods, such as PCR, offer a rapid, sensitive and specific means of detecting pathogens, however loss of sensitivity and lack of robustness have been reported when PCR is applied to heterogeneous and complex food matrices. The aim of this study was to establish a rapid, reliable and sensitive molecular method to detect pathogens in food samples. Real-time PCR assays for the detection of Campylobacter jejuni and coli, Clostridium perfringens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica and Staphylococcus aureus in food enrichment samples were developed. A novel organism was constructed using a gfp gene cloned into the chromosome of a non-pathogenic Escherichia coli. Viable cells of the modified strain were encapsulated in Lenticule discs and used as process control in the PCR assays. MagNA Pure™ automated extraction was shown to be robust and reliable for preparing bacterial DNA from food enrichment broths. The PCR assays and MagNA Pure™ was applied to enrichment broths inoculated with 558 naturally-contaminated food and environmental samples in a field trial. Concordance was found between PCR results and those obtained using standard culture methods. Loss of assay sensitivity or PCR inhibition was detected in 6 % (32) of the enrichment samples. To improve the sensitivity the L monocytogenes hlyA gene PCR was nested. The assay was applied for the sensitive non-cultural diagnosis of listeriosis, with L monocytogenes detected in 15 of 17 clinical samples from patients with suspected listeriosis. In conclusion, these assays provided a high throughput, robust, reliable PCR detection methods that could be used in clinical and food testing laboratories. The methods will be essential in outbreak situations and could be further developed to detecting bacterial pathogens, viruses, parasites, new and emerging pathogens

Spin Order in Paired Quantum Hall States

We consider quantum Hall states at even-denominator filling fractions, especially $\nu=5/2$, in the limit of small Zeeman energy. Assuming that a paired quantum Hall state forms, we study spin ordering and its interplay with pairing. We give numerical evidence that at $\nu = 5/2$ an incompressible ground state will exhibit spontaneous ferromagnetism. The Ginzburg-Landau theory for the spin degrees of freedom of paired Hall states is a perturbed CP$^2$ model. We compute the coefficients in the Ginzburg-Landau theory by a BCS-Stoner mean field theory for coexisting order parameters, and show that even if repulsion is smaller than that required for a Stoner instability, ferromagnetic fluctuations can induce a partially or fully polarized superconducting state

PROGNOSTIC FACTORS IN PATIENTS WITH LUNG CANCER

No abstrac

PARALLEL COMPUTATIONS WITH LARGE-SCALE AIR\ud POLLUTION MODELS

Large-scale mathematical models are very powerful tools in the efforts to provide more\ud information and more detailed information about the pollution levels, especially about pollution\ud levels which exceed certain critical values.. However, the model used must satisfy at\ud least two conditions: (i) it must be verified that the model results are reliable and (ii) it\ud should be possible to carry out different study by using the model. It is clear that comprehensive\ud studies about relationships between different input parameters and the model results\ud can only be carried out (a) if the numerical methods used in the model are sufficiently\ud fast and (b) if the code runs efficiently on the available high-speed computers.\ud Some results obtained recently by a new unified version of the Danish Eulerian Model will\ud be presented in this paper

On the pulsating strings in Sasaki-Einstein spaces

We study the class of pulsating strings in AdS_5 x Y^{p,q} and AdS_5 x L^{p,q,r}. Using a generalized ansatz for pulsating string configurations, we find new solutions for this class in terms of Heun functions, and derive the particular case of AdS_5 x T^{1,1}, which was analyzed in arXiv:1006.1539 [hep-th]. Unfortunately, Heun functions are still little studied, and we are not able to quantize the theory quasi-classically and obtain the first corrections to the energy. The latter, due to AdS/CFT correspondence, is supposed to give the anomalous dimensions of operators of the gauge theory dual N=1 superconformal field theory.Comment: 9 pages, talk given at the 2nd Int. Conference AMiTaNS, 21-26 June 2010, Sozopol, Bulgaria, organized by EAC (Euro-American Consortium) for Promoting AMiTaNS, to appear in the Proceedings of 2nd Int. Conference AMiTaN

A Stochastic Approach for Investigation Ultrafast Phenomena in Semiconductors

2002 Mathematics Subject Classification: 65C05In this paper a stochastic approach is proposed for investigation the ultrafast evolution of electrons interacting with phonons in the presence of an applied electric field. The quantum-kinetic equation describing the above ultrafast phenomena contains polynomial non-linearity which allows to use the link between non-stationary iterative processes and the branching stochastic processes. The considered stochastic approach relies on the numerical Monte Carlo (MC) theory as applied to the integral form of the quantum-kinetic equation and estimates the electron energy distribution using statistical averages over long evolution times. The numerical tests were performed for GaAs material parameters. The numerical results for the electron energy distribution function in the case of a non-linear electron quantum transport is compared with the obtained results in the linear case.Supported by Center of Excellence BIS-21 grant ICA1-2000-70016 and by the NSF of Bulgaria under Grants # I 811/98 and # MM 902/99