736 research outputs found

    Lossless polarization attraction of co-propagating beams in telecom fibers

    Get PDF
    4We study the performance of a nonlinear lossless polarizer (NLP), the device that transforms an input arbitrary state of polarization (SOP) of a signal beam into one and the same SOP toward the output and, unlike conventional passive polarizers, performs this transformation without polarization-dependent losses. The operation principle of this device is based on the nonlinear rotation of the SOP of the strong signal beam under the interaction with a copropagating strong pump beam in a Kerr medium, which in our case is a telecom fiber. We quantify the performance of this NLP by introducing the notion of instantaneous degree of polarization, which is a natural extension of the conventional notion of the degree of polarization appropriate for CW beams to the case of pulses whose SOP is not constant across the pulse. We pay particular attention to the regime when signal and pump beams experience a walk-off in the dispersive medium. In particular, we demonstrate that a signal pulse experiences much stronger repolarization when the walk-off effect is present as compared with the case of no walk-off. We also study the degradation of the efficiency of the NLP in the presence of polarization mode dispersion.openopenV. Kozlov; M. Barozzi; A. Vannucci; S. WabnitzKozlov, Victor; M., Barozzi; A., Vannucci; Wabnitz, Stefa

    Non-Newtonian and flow pulsatility effects in simulation models of a stented intracranial aneurysm

    Get PDF
    Permission to redistribute provided by publishers.Three models of different stent designs implanted in a cerebral aneurysm, originating from the Virtual Intracranial Stenting Challenge'07, are meshed and the flow characteristics simulated using commercial computational fluid dynamics (CFD) software in order to investigate the effects of non-Newtonian viscosity and pulsatile flow. Conventional mass inflow and wall shear stress (WSS) output are used as a means of comparing the cfd simulations. In addition, a WSS distribution is presented, which clearly discriminates in favour of the stent design identified by other groups. It is concluded that non-Newtonian and pulsatile effects are important to include in order to avoid underestimating wss, to understand dynamic flow effects, and to discriminate more effectively between stent designs. © Authors 2011

    Bifurcations of Natural Convection Flows from an Enclosed Cylindrical Heat Source

    Get PDF
    A numerical analysis of transitional natural convection from a confined thermal source is presented. The system considered is an air-filled, square-sectioned 2D enclosure containing a horizontal heated cylinder. The resulting flow is investigated with respect to the variation of the Rayleigh number, for three values of the aspect ratio A. The first bifurcation of the low-Ra fixed-point solution is tracked for each A-value. Chaotic flow features are detailed for the case A = 2.5. The supercritical behaviour of the system is investigated using nonlinear analysis tools and phase-space representations, and the effect of the flow on heat transfer is discussed

    R705H mutation of MYH9 is associated with MYH9-related disease and not only with non-syndromic deafness DFNA17

    Get PDF
    MYH9-related disease (MYH9-RD) is a rare autosomal dominant disease caused by mutation of MYH9, the gene encoding for the heavy chain of non-muscle myosin IIA (NMMHC-IIA). MYH9-RD patients have macrothrombocytopenia and granulocyte inclusions (pathognomonic sign of the disease) containing wild-type and mutant NMMHC-IIA. During life they might develop sensorineural hearing loss, cataract, glomerulonephritis, and elevation of liver enzymes. One of the MYH9 mutations, p.R705H, was previously reported to be associated with DFNA17, an autosomal dominant non-syndromic sensorineural hearing loss without any other features associated. We identified the same mutation in two unrelated families, whose four affected individuals had not only hearing impairment but also thrombocytopenia, giant platelets, leukocyte inclusions, as well as mild to moderate elevation of some liver enzymes. Our data suggest that DFNA17 should not be a separate genetic entity but part of the wide phenotypic spectrum of MYH9-RD characterized by congenital hematological manifestations and variable penetrance and expressivity of the extra-hematological features

    Sensitive detection of circulating breast cancer cells by reverse-transcriptase polymerase chain reaction of maspin gene

    Get PDF
    Background: Maspin, a recently identified protein related to the family of serpins, is believed to play a role in human breast cancer. In an effort to improve the present methods of detection, we have developed a reverse-transcriptase polymerase chain reaction (RT-PCR) assay for maspin transcript to identify small numbers of mammary carcinoma cells in the peripheral blood and bone marrow of patients with breast cancer. Patients and methods: Five non-neoplastic mammary tissue samples, 13 breast cancer specimens as well as 17 peripheral blood and 4 bone marrow samples from normal subjects were screened for the presence of maspin mRNA by RT-PCR. The same assay was applied to peripheral blood or bone marrow samples obtained from 29 patients with stages I to IV breast cancer. Results: By RT-PCR it was possible to amplify maspin mRNA in all of the primary and metastatic breast cancer specimens, but in none of the normal hemopoietic samples from healthy donors. Thus, detection of maspin transcript in the peripheral blood or marrow of a patient known to have breast cancer is indicative of the presence of mammary carcinoma cells. In reconstitution experiments, maspin RT-PCR reliably detected 10 mammary carcinoma cells in 1 million normal peripheral-blood mononuclear cells (PBMCs). None of the 9 patients with stages I, II, or III breast cancer had maspin transcript in peripheral blood. Of note, 3 of 9 patients with stage TV breast cancer receiving systemic therapy at the time of sample collection, but only I of 11 patients with stage IV not receiving therapy, had detectable maspin transcript in peripheral blood. Moreover, 3 marrow specimens from stage TV patients tested positive by this assay. Conclusions: This pilot study suggests that maspin RT-PCR assay is a sensitive, specific and sufficiently rapid method for detection of small numbers of circulating cells and marrow micrometastases in breast cancer patients. The possibility of applying this assay in the detection of tumor cell contamination of both marrow and stem-cell apheresis harvests of breast cancer patients merits further investigation
    corecore