Double-Electromagnetically Induced Transparency in a Y-type atomic system

We study the absorption and dispersion properties of a weak tunable probe field in a four-level Y-type atomic system driven by two strong laser (coupling) fields within the framework of density matrix formalism. It is found that the probe absorption profile displays double-electromagnetically induced transparency (double-EIT) and it is shown how to control it by changing the Rabi frequencies as well as the atom field detuning of the coupling fields.Comment: 8 page

A Fabry-Perot interferometer with quantum mirrors: nonlinear light transport and rectification

Optical transport represents a natural route towards fast communications, and it is currently used in large scale data transfer. The progressive miniaturization of devices for information processing calls for the microscopic tailoring of light transport and confinement at length scales appropriate for the upcoming technologies. With this goal in mind, we present a theoretical analysis of a one-dimensional Fabry-Perot interferometer built with two highly saturable nonlinear mirrors: a pair of two-level systems. Our approach captures non-linear and non-reciprocal effects of light transport that were not reported previously. Remarkably, we show that such an elementary device can operate as a microscopic integrated optical rectifier

Undirected Graphs of Entanglement Two

Entanglement is a complexity measure of directed graphs that origins in fixed point theory. This measure has shown its use in designing efficient algorithms to verify logical properties of transition systems. We are interested in the problem of deciding whether a graph has entanglement at most k. As this measure is defined by means of games, game theoretic ideas naturally lead to design polynomial algorithms that, for fixed k, decide the problem. Known characterizations of directed graphs of entanglement at most 1 lead, for k = 1, to design even faster algorithms. In this paper we present an explicit characterization of undirected graphs of entanglement at most 2. With such a characterization at hand, we devise a linear time algorithm to decide whether an undirected graph has this property

Organic Thin Film Transistor with Carbon Nanotube Electrodes

The contact resistance between organic semiconductors and metallic electrodesaffectsthe performance of the organic thin film transistor (OTFT) negatively so that it may make thefield effect mobility of charge carrier seem small. In order to reduce the contact resistance weused conducting Carbon Nanotube (CNT) films, which consist of the same element as the basicmaterial of the organic semiconductors, as source or drain electrodes. The measurements oftransistor properties based on pentacene single crystals have been carried out by using both CNTfilm electrodes and metal electrode

Van-der-Waals potentials of paramagnetic atoms

We study single- and two-atom van der Waals interactions of ground-state atoms which are both polarizable and paramagnetizable in the presence of magneto-electric bodies within the framework of macroscopic quantum electrodynamics. Starting from an interaction Hamiltonian that includes particle spins, we use leading-order perturbation theory for the van der Waals potentials expressed in terms of the polarizability and magnetizability of the atom(s). To allow for atoms embedded in media, we also include local-field corrections via the real-cavity model. The general theory is applied to the potential of a single atom near a half space and that of two atoms embedded in a bulk medium or placed near a sphere, respectively.Comment: 18 pages, 3 figures, 1 tabl

Analytical evaluation of atomic form factors: application to Rayleigh scattering

Atomic form factors are widely used for the characterization of targets and specimens, from crystallography to biology. By using recent mathematical results, here we derive an analytical expression for the atomic form factor within the independent particle model constructed from nonrelativistic screened hydrogenic wavefunctions. The range of validity of this analytical expression is checked by comparing the analytically obtained form factors with the ones obtained within the Hartee-Fock method. As an example, we apply our analytical expression for the atomic form factor to evaluate the differential cross section for Rayleigh scattering off neutral atoms.Comment: 7 pages, 1 figur

Comparison of HIV-1 viral loads, CD4-Th2-lymphocytes and effects of praziquantel treatment among adults infected or uninfected with Schistosoma mansoni in fishing villages of north-western Tanzania

 Background: It is hypothesised that Th2 immunological environment associated with Schistosoma mansoni infection might favour replication of HIV-1 in co-infected individuals, results in increased viral loads. On the other hand, deworming using praziquantel might result in reduction of HIV-1 viral loads and increased CD4+ cell counts. This study was therefore, carried out to compare HIV -1 plasma loads, CD4-Th2-lymphocytes and the effects of praziquantel treatment on HIV-1 plasma loads and CD4+ cell counts among HIV-1 seropositive individuals infected or uninfected with S. mansoni.Methodology: A 9-month prospective longitudinal study was conducted among HIV-1 infected individuals aged 21-55 years with CD4+ cell counts ≥ 350cells/µL in fishing villages of North-Western Tanzania. Single stool samples were examined for S. mansoni eggs using Kato Katz technique at 6-month follow-up and 12 weeks after treatment. Venous blood samples were collected at baseline, at three and six-month follow-up and 12 weeks after praziquantel treatment for HIV-1 plasma viral loads and CD4+ cell quantification.Results: Of the 50 HIV-1 infected participants at baseline, 44% (22/50, 95%CI; 30.58-58.35) were found to be co-infected with S. mansoni at 6-month follow-up with a mean of 93.26GM-epg (95%CI: 60.42-143.95). The median CD4+ cell counts did not differ significantly between individuals infected with HIV-1 and those co-infected with HIV-1 and S. mansoni at baseline (P=0.62), 3-month (P=0.64) and 6-month (P=0.41) follow-up. Monthly decrease in CD4+ cells did not differ significantly between the two groups at all follow-up points (-30.39cell/µL versus -31.35cells/µL, P=0.89). Those infected with S. mansoni had a significantly higher mean log10 HIV-1 plasma viral load at baseline (5.98 ± 3.06 versus 9.21 ± 1.91copies/ml, P<0.0001) and 3-month follow-up (8.19 ± 2.17 versus 9.44 ± 1.99copies/ml, P<0.042) compared to those infected with HIV-1 only. This difference was not evident at the time of S. mansoni diagnosis at 6-month time point. Praziquantel treatment in co-infected individuals (n=12) did not result in any change in CD4+ cell counts and mean HIV-1 plasma viral loads (t=-0.9156, P=0.38), comparing baseline and 3-month follow-up after treatment. No correlation was observed between log S. mansoni egg counts and log10 HIV-1 RNA viral loads (r=-0.066, P=0.77) at six-month follow-up in co-infected individuals (n=22).Conclusion: HIV-1 plasma viral loads varied significantly among mono and co-infected individuals at baseline and 3-month follow-up. However, CD4+ cell counts did not vary between the two groups at all follow-up time points. Praziquantel treatment of co-infected individuals did not result in changes in CD4+ cell counts and HIV-1 plasma viral loads