164 research outputs found

    Transience analysis of bursty traffic with erbium doped fiber amplifiers

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    Copyright © [2009] IEEE. Reprinted from ICTON 2009. ISBN 978-1-4244-4826-5. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.In this paper, we investigate experimentally the impact of optical amplifiers, namely Erbium Doped Fiber Amplifiers (EDFA) on Optical Burst Switching (OBS) networks, operating at 2.5 Gb/s (typical bit rate for current passive optical networks - PON). Bursts with 212 – 1 and 216 – 1 pseudo random binary sequence (PRBS) were studied, with different idle times. The use of traffic with variable idle time was assessed in order to evaluate the effect on the burst initial amplitude. We also analyzed the performance of the packet based system by measuring the Q factor at the receiver and concluded that the performance is not affected by the type of traffic (variable or fixed idle times)

    Arabidopsis thaliana response to extracellular dna: Self versus nonself exposure

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    The inhibitory effect of extracellular DNA (exDNA) on the growth of conspecific individuals was demonstrated in different kingdoms. In plants, the inhibition has been observed on root growth and seed germination, demonstrating its role in plant\u2013soil negative feedback. Several hypotheses have been proposed to explain the early response to exDNA and the inhibitory effect of conspecific exDNA. We here contribute with a whole-plant transcriptome profiling in the model species Arabidopsis thaliana exposed to extracellular self-(conspecific) and nonself-(heterologous) DNA. The results highlight that cells distinguish self-from nonself-DNA. Moreover, confocal microscopy analyses reveal that nonself-DNA enters root tissues and cells, while self-DNA remains outside. Specifically, exposure to self-DNA limits cell permeability, affecting chloroplast functioning and reactive oxygen species (ROS) production, eventually causing cell cycle arrest, consistently with macroscopic observations of root apex necrosis, increased root hair density and leaf chlorosis. In contrast, nonself-DNA enters the cells triggering the activation of a hypersensitive response and evolving into systemic acquired resistance. Complex and different cascades of events emerge from exposure to extracellular selfor nonself-DNA and are discussed in the context of Damage-and Pathogen-Associated Molecular Patterns (DAMP and PAMP, respectively) responses

    Bithiazole Inhibitors of Phosphatidylinositol 4-Kinase (PI4KIIIβ) as Broad-Spectrum Antivirals Blocking the Replication of SARS-CoV-2, Zika Virus, and Human Rhinoviruses

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    Over half a century since the description of the first antiviral drug, “old” re-emerging viruses and “new” emerging viruses still represent a serious threat to global health. Their high mutation rate and rapid selection of resistance toward common antiviral drugs, together with the increasing number of co-infections, make the war against viruses quite challenging. Herein we report a host-targeted approach, based on the inhibition of the lipid kinase PI4KIIIβ, as a promising strategy for inhibiting the replication of multiple viruses hijacking this protein. We show that bithiazole inhibitors of PI4KIIIβ block the replication of human rhinoviruses (hRV), Zika virus (ZIKV) and SARS-CoV-2 at low micromolar and sub-micromolar concentrations. However, while the anti-hRV/ZIKV activity can be directly linked to PI4KIIIβ inhibition, the role of PI4KIIIβ in SARS-CoV-2 entry/replication is debated

    The brief international cognitive assessment for multiple sclerosis (BICAMS): Normative values with gender, age and education corrections in the Italian population

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    Background: BICAMS (Brief International Cognitive Assessment for Multiple Sclerosis) has been recently developed as brief, practical and universal assessment tool for cognitive impairment in MS subjects. It includes the Symbol Digit Modalities Test (SDMT), the California Verbal Learning Test-2 (CVLT2) and the Brief Visuospatial Memory Test-Revised (BVMT-R) . In this study we aimed at gathering regression based normative data for the BICAMS battery in the Italian population.Methods: Healthy subjects were consecutively recruited among patient friends and relatives. Corrections for demographics were calculated using multivariable linear regression models. Test-retest reliability was assessed using the Pearson correlation coefficient.Results: The BICAMS battery was administered to 273 healthy subjects (180 women, mean age 38.9 ± 13.0 years, mean education 14.9 ± 3.0 years). Test-retest reliability was good for all the tests.Conclusions: The study provided normative data of the BICAMS for the Italian population confirming good test-retest reliability which can facilitate the use of the battery in clinical practice, also for longitudinal patient assessments

    Measurement of the Generalized Forward Spin Polarizabilities of the Neutron

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    The generalized forward spin polarizabilities γ0\gamma_0 and δLT\delta_{LT} of the neutron have been extracted for the first time in a Q2Q^2 range from 0.1 to 0.9 GeV2^2. Since γ0\gamma_0 is sensitive to nucleon resonances and δLT\delta_{LT} is insensitive to the Δ\Delta resonance, it is expected that the pair of forward spin polarizabilities should provide benchmark tests of the current understanding of the chiral dynamics of QCD. The new results on δLT\delta_{LT} show significant disagreement with Chiral Perturbation Theory calculations, while the data for γ0\gamma_0 at low Q2Q^2 are in good agreement with a next-to-lead order Relativistic Baryon Chiral Perturbation theory calculation. The data show good agreement with the phenomenological MAID model.Comment: 5 pages, 2 figures, corrected typo in author name, published in PR

    Q^2 Evolution of the Neutron Spin Structure Moments using a He-3 Target

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    We have measured the spin structure functions g1g_1 and g2g_2 of 3^3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.07 GeV off a polarized 3^3He target at a 15.5^{\circ} scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q2Q^2 evolution of Γ1(Q2)=01g1(x,Q2)dx\Gamma_1(Q^2)=\int_0^{1} g_1(x,Q^2) dx, Γ2(Q2)=01g2(x,Q2)dx\Gamma_2(Q^2)=\int_0^1 g_2(x,Q^2) dx and d2(Q2)=01x2[2g1(x,Q2)+3g2(x,Q2)]dxd_2 (Q^2) = \int_0^1 x^2[ 2g_1(x,Q^2) + 3g_2(x,Q^2)] dx for the neutron in the range 0.1 GeV2^2 Q2\leq Q^2 \leq 0.9 GeV2^2 with good precision. Γ1(Q2) \Gamma_1(Q^2) displays a smooth variation from high to low Q2Q^2. The Burkhardt-Cottingham sum rule holds within uncertainties and d2d_2 is non-zero over the measured range.Comment: 5 pages, 2 figures, submitted to Phys. Rev. Lett.. Updated Hermes data in Fig. 2 (top panel) and their corresponding reference. Updated the low x extrapolation error Fig. 2 (middle panel). Corrected references to ChiPT calculation

    The Q^2 evolution of the generalized Gerasimov-Drell-Hearn integral for the neutron using a He-3 target

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    We present data on the inclusive scattering of polarized electrons from a polarized He-3 target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5 degrees. Our data include measurements from the quasielastic peak, through the resonance region, to the beginning of the deep inelastic regime, and were used to determine the spin difference in the virtual photoabsorption cross section. We extract the extended Gerasimov-Drell-Hearn integral for the neutron in the range of 4-momentum transfer squared Q^2 of 0.1-0.9 GeV.Comment: 14 pages of text when TeXed in preprint format with figures embedded. RevTeX format. Three eps figure

    Precision Determination of the Neutron Spin Structure Function g1n

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    We report on a precision measurement of the neutron spin structure function g1ng^n_1 using deep inelastic scattering of polarized electrons by polarized ^3He. For the kinematic range 0.014<x<0.7 and 1 (GeV/c)^2< Q^2< 17 (GeV/c)^2, we obtain 0.0140.7g1n(x)dx=0.036±0.004(stat)±0.005(syst)\int^{0.7}_{0.014} g^n_1(x)dx = -0.036 \pm 0.004 (stat) \pm 0.005 (syst) at an average Q2=5(GeV/c)2Q^2=5 (GeV/c)^2. We find relatively large negative values for g1ng^n_1 at low xx. The results call into question the usual Regge theory method for extrapolating to x=0 to find the full neutron integral 01g1n(x)dx\int^1_0 g^n_1(x)dx, needed for testing quark-parton model and QCD sum rules.Comment: 5 pages, 3 figures To be published in Phys. Rev. Let

    Monte-Carlo dosimetry on a realistic cell monolayer geometry exposed to alpha particles

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    The energy and specific energy absorbed in the main cell compartments (nucleus and cytoplasm) in typical radiobiology experiments are usually estimated by calculations as they are not accessible for a direct measurement. In most of the work, the cell geometry is modelled using the combination of simple mathematical volumes. We propose a method based on high resolution confocal imaging and ion beam analysis (IBA) in order to import realistic cell nuclei geometries in Monte-Carlo simulations and thus take into account the variety of different geometries encountered in a typical cell population. Seventy-six cell nuclei have been imaged using confocal microscopy and their chemical composition has been measured using IBA. A cellular phantom was created from these data using the ImageJ image analysis software and imported in the Geant4 Monte-Carlo simulation toolkit. Total energy and specific energy distributions in the 76 cell nuclei have been calculated for two types of irradiation protocols: a 3 MeV alpha particle microbeam used for targeted irradiation and a 239Pu alpha source used for large angle random irradiation. Qualitative images of the energy deposited along the particle tracks have been produced and show good agreement with images of DNA double strand break signalling proteins obtained experimentally. The methodology presented in this paper provides microdosimetric quantities calculated from realistic cellular volumes. It is based on open-source oriented software that is publicly available

    Measurement of the Proton and Deuteron Spin Structure Functions g2 and Asymmetry A2

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    We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 1.0 < Q^2 < 30(GeV/c)^2 by scattering 38.8 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets.The absolute value of A2 is significantly smaller than the sqrt{R} positivity limit over the measured range, while g2 is consistent with the twist-2 Wandzura-Wilczek calculation. We obtain results for the twist-3 reduced matrix elements d2p, d2d and d2n. The Burkhardt-Cottingham sum rule integral - int(g2(x)dx) is reported for the range 0.02 < x < 0.8.Comment: 12 pages, 4 figures, 1 tabl
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