Application de l'algorithme Principal Component Inverse 3D pour la détection de mines enfouies

- Cet article s'intéresse à la réduction de fausses alarmes dans le cadre de la détection de mines sous marines enfouies. Nous proposons d'utiliser un algorithme algèbrique. le Principal Component Inverse 3D, pour réduire l'influence de la réverbération et séparer les échos de mines entre eux. Cette méthode est testée sur des données réelles fournies par le GESMA et les résultats sont comparés à ceux donnés par des algorithmes algébriques 2D

Can optical squeezing be generated via polarization self-rotation in a thermal vapour cell?

The traversal of an elliptically polarized optical field through a thermal vapour cell can give rise to a rotation of its polarization axis. This process, known as polarization self-rotation (PSR), has been suggested as a mechanism for producing squeezed light at atomic transition wavelengths. In this paper, we show results of the characterization of PSR in isotopically enhanced Rubidium-87 cells, performed in two independent laboratories. We observed that, contrary to earlier work, the presence of atomic noise in the thermal vapour overwhelms the observation of squeezing. We present a theory that contains atomic noise terms and show that a null result in squeezing is consistent with this theory.Comment: 10 pages, 11 figures, submitted to PRA. Please email author for a PDF file if the article does not appear properl

Highly non-Gaussian states created via cross-Kerr nonlinearity

We propose a feasible scheme for generation of strongly non-Gaussian states using the cross-Kerr nonlinearity. The resultant states are highly non-classical states of electromagnetic field and exhibit negativity of their Wigner function, sub-Poissonian photon statistics, and amplitude squeezing. Furthermore, the Wigner function has a distinctly pronounced ``banana'' or ``crescent'' shape specific for the Kerr-type interactions, which so far was not demonstrated experimentally. We show that creating and detecting such states should be possible with the present technology using electromagnetically induced transparency in a four-level atomic system in N-configuration.Comment: 12 pages, 7 figure

Propagation of Squeezed Vacuum under Electromagnetically Induced Transparency

We experimentally and theoretically analyze the transmission of continuous-wave and pulsed squeezed vacuum through rubidium vapor under the conditions of electromagnetically induced transparency. Frequency- and time-domain homodyne tomography is used to measure the quadrature noise and reconstruct the quantum states of the transmitted light. A simple theoretical model explains the spectrum and degradation of the transmitted squeezing with high precision

Towards high-speed optical quantum memories

Quantum memories, capable of controllably storing and releasing a photon, are a crucial component for quantum computers and quantum communications. So far, quantum memories have operated with bandwidths that limit data rates to MHz. Here we report the coherent storage and retrieval of sub-nanosecond low intensity light pulses with spectral bandwidths exceeding 1 GHz in cesium vapor. The novel memory interaction takes place via a far off-resonant two-photon transition in which the memory bandwidth is dynamically generated by a strong control field. This allows for an increase in data rates by a factor of almost 1000 compared to existing quantum memories. The memory works with a total efficiency of 15% and its coherence is demonstrated by directly interfering the stored and retrieved pulses. Coherence times in hot atomic vapors are on the order of microsecond - the expected storage time limit for this memory.Comment: 13 pages, 5 figure

Stented ureterovesical anastomosis in renal transplantation: does it influence the rate of urinary tract infections?

<p>Abstract</p> <p>Objective</p> <p>Our objective was to evaluate the impact of routine use of double-J stents on the incidence of urinary tract infection after renal transplantation.</p> <p>Methods</p> <p>We conducted a retrospective-comparative single-centre study in 310 consecutive adult deceased donor kidney recipients transplanted from 2002 to 2006. Patients were divided in two groups, with or without urinary stent implantation. To evaluate the predictive factors for UTI, donor and recipients pre- and post-transplantation data were analysed. Early urological complications and renal function within 12 months of transplantation were included as well.</p> <p>Results</p> <p>A total of 157 patients were enrolled to a stent (ST) and 153 patients to a no-stent (NST) group. The rate of urinary tract infection at three months was similar between the two groups (43.3% ST vs. 40.1% NST, p = 0.65). Of the identified pathogens Enterococcus and Escherichia coli were the most common species. In multivariate analysis neither age nor immunosuppressive agents, BMI or diabetes seemed to have influence on the rate of UTI. When compared to males, females had a significantly higher risk for UTI (54.0% vs. 33.5%).</p> <p>Conclusion</p> <p>Prophylactic stenting of the ureterovesical anastomosis does not increase the risk of urinary tract infection in the early postoperative period.</p

EPHA2 Is Associated with Age-Related Cortical Cataract in Mice and Humans

Age-related cataract is a major cause of blindness worldwide, and cortical cataract is the second most prevalent type of age-related cataract. Although a significant fraction of age-related cataract is heritable, the genetic basis remains to be elucidated. We report that homozygous deletion of Epha2 in two independent strains of mice developed progressive cortical cataract. Retroillumination revealed development of cortical vacuoles at one month of age; visible cataract appeared around three months, which progressed to mature cataract by six months. EPHA2 protein expression in the lens is spatially and temporally regulated. It is low in anterior epithelial cells, upregulated as the cells enter differentiation at the equator, strongly expressed in the cortical fiber cells, but absent in the nuclei. Deletion of Epha2 caused a significant increase in the expression of HSP25 (murine homologue of human HSP27) before the onset of cataract. The overexpressed HSP25 was in an underphosphorylated form, indicating excessive cellular stress and protein misfolding. The orthologous human EPHA2 gene on chromosome 1p36 was tested in three independent worldwide Caucasian populations for allelic association with cortical cataract. Common variants in EPHA2 were found that showed significant association with cortical cataract, and rs6678616 was the most significant in meta-analyses. In addition, we sequenced exons of EPHA2 in linked families and identified a new missense mutation, Arg721Gln, in the protein kinase domain that significantly alters EPHA2 functions in cellular and biochemical assays. Thus, converging evidence from humans and mice suggests that EPHA2 is important in maintaining lens clarity with age

Novel haptoglobin insertion/deletion polymorphism is associated with the lipid profile and C-reactive protein (CRP) concentration.

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