Perspectives of Long-Haul WDM Transmission Systems Based on Phase-Insensitive Fiber-Optic Parametric Amplifiers

International audienceThe deployment of phase-insensitive fiber-optic parametric amplifiers (PI-FOPAs) as inline amplifiers in long-haul WDM transmission systems is discussed, and it is outlined how to design PI-FOPAs to be a valuable upgrade option for this application

Relevance of ferromagnetic correlations for the Electron Spin Resonance in Kondo lattice systems

Electron Spin Resonance (ESR) measurements of the ferromagnetic Kondo lattice system CeRuPO show a well defined ESR signal which is related to the magnetic properties of the Ce3+ moment. In contrast, no ESR signal could be observed in the antiferromagnetic homologue CeOsPO. Additionally, we detect an ESR signal in a further ferromagnetic Yb compound, YbRh, while it was absent in a number of Ce or Yb intermetallic compounds with dominant antiferromagnetic exchange, independently of the presence of a strong Kondo interaction or the proximity to a (quantum) critical point. Thus, the observation of an ESR signal in a Kondo lattice is neither specific to Yb nor to the proximity of a quantum critical point, but seems to be connected to the presence of ferromagnetic fluctuations. These conclusions not only provide a basic concept to understand the ESR in Kondo lattice systems even well below the Kondo temperature as observed in the heavy fermion metal YbRh2Si2 but point out ESR as a prime method to investigate directly the spin dynamics of the Kondo ion.Comment: 5 pages, 2 figures, 1 tabl

Quasi-degenerate self-trapping in one-dimensional charge transfer exciton

The self-trapping by the nondiagonal particle-phonon interaction between two quasi-degenerate energy levels of excitonic system, is studied. We propose this is realized in charge transfer exciton, where the directions of the polarization give the quasi-degeneracy. It is shown that this mechanism, unlike the conventional diagonal one, allows a coexistence and resonance of the free and self-trapped states even in one-dimensional systems and a quantitative theory for the optical properties (light absorption and time-resolved luminescence) of the resonating states is presented. This theory gives a consistent resolution for the long-standing puzzles in quasi-one-dimensional compound A-PMDA.Comment: accepted to Phys. Rev. Letter

Normal-superconducting transition induced by high current densities in YBa2Cu3O7-d melt-textured samples and thin films: Similarities and differences

Current-voltage characteristics of top seeded melt-textured YBa2Cu3O7-d are presented. The samples were cut out of centimetric monoliths. Films characteristics were also measured on microbridges patterned on thin films grown by dc sputtering. For both types of samples, a quasi-discontinuity or quenching was observed for a current density J* several times the critical current density Jc. Though films and bulks much differ in their magnitude of both Jc and J*, a proposal is made as to a common intrinsic origin of the quenching phenomenon. The unique temperature dependence observed for the ratio J*/Jc, as well as the explanation of the pre-quenching regime in terms of a single dissipation model lend support to our proposal.Comment: 10 pages, 10 figures, submitted to Physical Review

Effect of incubation temperature on the diagnostic sensitivity of the glanders complement fixation test

Summary The complement fixation test (CFT) is the only serological test prescribed by the World Organisation for Animal Health (OIE) for the diagnosis of glanders in international trading of equids. However, false-positive reactions have caused financial losses to the animal owners in the past, and false-negative tests have resulted in the introduction of glanders into healthy equine populations in previously glanders-free areas. Both warm (incubation at 37°C for 1 h) and cold (overnight incubation at 4°C) procedures are recommended by the OIE for serodiagnosis of glanders. In a comparison of the sensitivity and specificity of the two techniques, using the United States Department of Agriculture antigen, warm CFT was found to be significantly less sensitive (56.8%; p < 0.0005) than the cold CFT (83.6%). Cold CFT thus increases the detection rate of glanders but a lower diagnostic specificity has to be accepted. The immunoblot was used as the gold standard

Crystalline Gaq3Nanostructures: Preparation, Thermal Property and Spectroscopy Characterization

Crystalline Gaq31-D nanostructures and nanospheres could be fabricated by thermal evaporation under cold trap. The influences of the key process parameters on formation of the nanostructures were also investigated. It has been demonstrated that the morphology and dimension of the nanostructures were mainly controlled by working temperature and working pressure. One-dimensional nanostructures were fabricated at a lower working temperature, whereas nanospheres were formed at a higher working temperature. Larger nanospheres could be obtained when a higher working pressure was applied. The XRD, FTIR, and NMR analyses evidenced that the nanostructures mainly consisted of δ-phase Gaq3. Their DSC trace revealed two small exothermic peaks in addition to the melting endotherm. The one in lower temperature region was ascribed to a transition from δ to β phase, while another in higher temperature region could be identified as a transition from β to δ phase. All the crystalline nanostructures show similar PL spectra due to absence of quantum confinement effect. They also exhibited a spectral blue shift because of a looser interligand spacing and reduced orbital overlap in their δ-phase molecular structures

Comparison of diagnostic tests for the detection of Brucella spp. in camel sera

<p>Abstract</p> <p>Background</p> <p>Brucellosis in livestock causes enormous losses for economies of developing countries and poses a severe health risk to consumers of dairy products. Little information is known especially on camel brucellosis and its impact on human health. For surveillance and control of the disease, sensitive and reliable detection methods are needed. Although serological tests are the mainstay of diagnosis in camel brucellosis, these tests have been directly transposed from cattle without adequate validation. To date, little information on application of real-time PCR for detection of <it>Brucella </it>in camel serum is available. Therefore, this study was performed to compare the diagnostic efficiency of different serological tests and real-time PCR in order to identify the most sensitive, rapid and simple combination of tests for detecting <it>Brucella </it>infection in camels.</p> <p>Findings</p> <p>A total of 895 serum samples collected from apparently healthy Sudanese camels was investigated. Sudan is a well documented endemic region for brucellosis with cases in humans, ruminants, and camels. Rose Bengal Test (RBT), Complement Fixation Test (CFT), Slow Agglutination Test (SAT), Competitive Enzyme Linked Immunosorbant Assay (cELISA) and Fluorescence Polarization Assay (FPA) as well as real-time PCR were used. Our findings revealed that <it>bcsp31 </it>kDa real-time PCR detected <it>Brucella </it>DNA in 84.8% (759/895) of the examined samples, of which 15.5% (118/759) were serologically negative. Our results show no relevant difference in sensitivity between the different serological tests. FPA detected the highest number of positive cases (79.3%) followed by CFT (71.4%), RBT (70.7%), SAT (70.6%) and cELISA (68.8%). A combination of real-time PCR with one of the used serological tests identified brucellosis in more than 99% of the infected animals. 59.7% of the examined samples were positive in all serological tests and real-time PCR. A subpopulation of 6.8% of animals was positive in all serological tests but negative in real-time PCR assays. The high percentage of positive cases in this study does not necessarily reflect the seroprevalence of the disease in the country but might be caused by the fact that the camels were imported from brucellosis infected herds of Sudan, accidentally. Seroprevalence of brucellosis in camels should be examined in confirmatory studies to evaluate the importance of brucellosis in this animal species.</p> <p>Conclusion</p> <p>We suggest combining <it>bcsp31 </it>real-time PCR with either FPA, CFT, RBT or SAT to screen camels for brucellosis.</p

Monitoring the orientation of rare-earth-doped nanorods for flow shear tomography

Rare-earth phosphors exhibit unique luminescence polarization features originating from the anisotropic symmetry of the emitter ion's chemical environment. However, to take advantage of this peculiar property, it is necessary to control and measure the ensemble orientation of the host particles with a high degree of precision. Here, we show a methodology to obtain the photoluminescence polarization of Eu-doped LaPO4 nano rods assembled in an electrically modulated liquid-crystalline phase. We measure Eu3+ emission spectra for the three main optimal configurations ({\sigma}, {\pi} and {\alpha}, depending on the direction of observation and the polarization axes) and use them as a reference for the nano rod orientation analysis. Based on the fact that flowing nano rods tend to orient along the shear strain profile, we use this orientation analysis to measure the local shear rate in a flowing liquid. The potential of this approach is then demonstrated through tomographic imaging of the shear rate distribution in a microfluidic system.Comment: 8 pages, 3 figures + supplementary files for experimental and numerical method