A Scalar Wigner Theory for Polarized Light in Nonlinear Kerr Media

A scalar Wigner distribution function for describing polarized light is proposed in analogy with the treatment of spin variables in quantum kinetic theory. The formalism is applied to the propagation of circularly polarized light in nonlinear Kerr media and an extended phase space evolution equation is derived along with invariant quantities. We further consider modulation instability as well as the extension to partially coherent fields.Comment: 6 page

Spin solitons in magnetized pair plasmas

A set of fluid equations, taking into account the spin properties of the electrons and positrons in a magnetoplasma, are derived. The magnetohydrodynamic limit of the pair plasma is investigated. It is shown that the microscopic spin properties of the electrons and positrons can lead to interesting macroscopic and collective effects in strongly magnetized plasmas. In particular, it is found that new Alfvenic solitary structures, governed by a modified Korteweg-de Vries equation, are allowed in such plasmas. These solitary structures vanish if the quantum spin effects are neglected. Our results should be of relevance for astrophysical plasmas, e.g. in pulsar magnetospheres.Comment: 7 page

New Quantum Limits in Plasmonic Devices

Surface plasmon polaritons (SPPs) have recently been recognized as an important future technique for microelectronics. Such SPPs have been studied using classical theory. However, current state-of-the-art experiments are rapidly approaching nanoscales, and quantum effects can then become important. Here we study the properties of quantum SPPs at the interface between an electron quantum plasma and a dielectric material. It is shown that the effect of quantum broadening of the transition layer is most important. In particular, the damping of SPPs does not vanish even in the absence of collisional dissipation, thus posing a fundamental size limit for plasmonic devices. Consequences and applications of our results are pointed out.Comment: 5 pages, 2 figures, to appear in Europhysics Letter

Graviton mediated photon-photon scattering in general relativity

In this paper we consider photon-photon scattering due to self-induced gravitational perturbations on a Minkowski background. We focus on four-wave interaction between plane waves with weakly space and time dependent amplitudes, since interaction involving a fewer number of waves is excluded by energy-momentum conservation. The Einstein-Maxwell system is solved perturbatively to third order in the field amplitudes and the coupling coefficients are found for arbitrary polarizations in the center of mass system. Comparisons with calculations based on quantum field theoretical methods are made, and the small discrepances are explained.Comment: 5 pages, 3 figure

A possibility to measure elastic photon--photon scattering in vacuum

Photon--photon scattering in vacuum due to the interaction with virtual electron-positron pairs is a consequence of quantum electrodynamics. A way for detecting this phenomenon has been devised based on interacting modes generated in microwave waveguides or cavities [G. Brodin, M. Marklund and L. Stenflo, Phys. Rev. Lett. \textbf{87} 171801 (2001)]. Here we materialize these ideas, suggest a concrete cavity geometry, make quantitative estimates and propose experimental details. It is found that detection of photon-photon scattering can be within the reach of present day technology.Comment: 7 pages, 3 figure

Hrp59, an hnRNP M protein in Chironomus and Drosophila, binds to exonic splicing enhancers and is required for expression of a subset of mRNAs

Here, we study an insect hnRNP M protein, referred to as Hrp59. Hrp59 is relatively abundant, has a modular domain organization containing three RNA-binding domains, is dynamically recruited to transcribed genes, and binds to premRNA cotranscriptionally. Using the Balbiani ring system of Chironomus, we show that Hrp59 accompanies the mRNA from the gene to the nuclear envelope, and is released from the mRNA at the nuclear pore. The association of Hrp59 with transcribed genes is not proportional to the amount of synthesized RNA, and in vivo Hrp59 binds preferentially to a subset of mRNAs, including its own mRNA. By coimmunoprecipitation of Hrp59–RNA complexes and microarray hybridization against Drosophila whole-genome arrays, we identify the preferred mRNA targets of Hrp59 in vivo and show that Hrp59 is required for the expression of these target mRNAs. We also show that Hrp59 binds preferentially to exonic splicing enhancers and our results provide new insights into the role of hnRNP M in splicing regulation

Ferroplasmas: Magnetic Dust Dynamics in a Conducting Fluid

We consider a dusty plasma, in which the dust particles have a magnetic dipole moment. A Hall-MHD type of model, generalized to account for the intrinsic magnetization, is derived. The model is shown to be energy conserving, and the energy density and flux is derived. The general dispersion relation is then derived, and we show that kinetic Alfv\'en waves exhibit an instability for a low temperature and high density plasma. We discuss the implication of our results.Comment: 6 pages, 1 figur

Detection of QED vacuum nonlinearities in Maxwell's equations by the use of waveguides

We present a novel method for detecting nonlinearities, due to quantum electrodynamics through photon-photon scattering, in Maxwell's equation. The photon-photon scattering gives rise to self-interaction terms, which are similar to the nonlinearities due to the polarisation in nonlinear optics. These self-interaction terms vanish in the limit of parallel propagating waves, but if instead of parallel propagating waves the modes generated in wavesguides are used, there will be a non-zero total effect. Based on this idea, we calculate the nonlinear excitation of new modes and estimate the strength of this effect. Furthermore, we suggest a principal experimental setup.Comment: 4 pages, REVTeX3. To appear in Phys. Rev. Let

High throughput screening for identification of mycolactone targets : Relations between M. ulcerans and nervous system

Buruli ulcer is an infectious disease transmitted by arthropod vectors harboring Mycobacterium ulcerans, a mycobacterium which belong to the same family of bacteria causing tuberculosis and leprosy. The infection causes painless swelling and severe skin lesions. One key feature of M. ulcerans bacterium is its ability to secrete a necrotic toxin, the mycolactone within small lipophilic vesicles, which are critical for the bacterial induced cytotoxicity. The biological knowledge as well as the preventive and therapeutic means for this invalidating disease is still very limited.   Our first approach was to investigate whether the mycolactone toxin could be involved in the neutralization of pain by acting directly on the peripheral nervous system without causing destruction of nervous fibers. By use of live time fluorescence microscopy and appropriate markers, we showed that the addition of toxin at sub-toxic dose provokes modification of ionic currents of neuron cells. Based on this ability of the toxin, a molecular high throughput methodology was developed for the screening of a genome wide siRNA library and small molecules inhibitors to enable the search of the cellular targets for the toxin. The cell-based assay relies on automated confocal microscopy on macrophages coupled with dedicated image analysis. These two screening allowed us to identify a putative toxin target, and a toxin inhibitor. A binding assay confirmed that the putative target is a receptor of the toxin. Together these results allowed us to build a potential signaling pathway activated by the mycolactone and implicated in ionic channel activities.   The second approach was to confirm this model in the mouse model of M. ulcerans infection and its role in the hypoesthesia of the lesions. Toxin inhibitor, daily administered to mice, which were experimentally infected by M. ulcerans, conducted to the absence of the hypoesthesia of the lesions. Furthermore, a histological study of neuronal fibers did not show a destruction of neuronal cells. Moreover, in vitro studies have showed that M. ulcerans are able to colonize neuronal cells. Then, these results suggested that the hypoesthesia of the M. ulcerans lesions could be caused by a non-destructive process of nervous cells.