11,119 research outputs found

    Effective penetration length and interstitial vortex pinning in superconducting films with regular arrays of defects

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    In order to compare magnetic and non-magnetic pinning we have nanostructured two superconducting films with regular arrays of pinning centers: Cu (non-magnetic) dots in one case, and Py (magnetic) dots in the other. For low applied magnetic fields, when all the vortices are pinned in the artificial inclusions, magnetic dots prove to be better pinning centers, as has been generally accepted. Unexpectedly, when the magnetic field is increased and interstitial vortices appear, the results are very different: we show how the stray field generated by the magnetic dots can produce an effective reduction of the penetration length. This results in strong consequences in the transport properties, which, depending on the dot separation, can lead to an enhancement or worsening of the transport characteristics. Therefore, the election of the magnetic or non-magnetic character of the pinning sites for an effective reduction of dissipation will depend on the range of the applied magnetic field.Comment: 10 pages, 3 figure

    Li-rich RGB stars in the Galactic Bulge

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    We present Lithium abundance determination for a sample of K giant stars in the galactic bulge. The stars presented here are the only 13 stars with detectable Lithium line (6767.18 A) among ~400 stars for which we have spectra in this wavelength range, half of them in Baade's Window (b=-4) and half in a field at b=-6. The stars were observed with the GIRAFFE spectrograph of FLAMES@VLT, with a spectral resolution of R~20,000. Abundances were derived via spectral synthesis and the results are compared with those for stars with similar parameters, but no detectable Li line. We find 13 stars with a detectable Li line, among which 2 have abundances A(Li)>2.7. No clear correlations were found between the Li abundance and those of other elements. With the exception of the two most Li rich stars, the others follow a fairly tight A(Li)-T_eff correlation. It would seems that there must be a Li production phase during the red giant branch (RGB), acting either on a very short timescale, or selectively only in some stars. The proposed Li production phase associated with the RGB bump cannot be excluded, although our targets are significantly brighter than the predicted RGB bump magnitude for a population at 8 kpcComment: 8 pages, 9 figures, accepted for publication in A&

    Resolving parameter degeneracies in long-baseline experiments by atmospheric neutrino data

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    In this work we show that the physics reach of a long-baseline (LBL) neutrino oscillation experiment based on a superbeam and a megaton water Cherenkov detector can be significantly increased if the LBL data are combined with data from atmospheric neutrinos (ATM) provided by the same detector. ATM data are sensitive to the octant of θ23\theta_{23} and to the type of the neutrino mass hierarchy, mainly through three-flavor effects in e-like events. This allows to resolve the so-called θ23\theta_{23}- and sign(Δm312\Delta m^2_{31})-parameter degeneracies in LBL data. As a consequence it becomes possible to distinguish the normal from the inverted neutrino mass ordering at 2σ2\sigma CL from a combined LBL+ATM analysis if sin22θ130.02\sin^2 2\theta_{13} \gtrsim 0.02. The potential to identify the true values of sin22θ13\sin^2 2\theta_{13} and the CP-phase δcp\delta_{cp} is significantly increased through the lifting of the degeneracies. These claims are supported by a detailed simulation of the T2K (phase II) LBL experiment combined with a full three-flavor analysis of ATM data in the HyperKamiokande detector.Comment: 25 pages, 10 figure

    Dependence on the Identification of the Scale Energy Parameter Q 2 in the Quark Distribution Functions for a DIS Production of Za

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    We discuss the Z-production in a DIS (Deep Inelastic Scattering) process e + p → e + Z + X using the Parton Model, within the context of the Standard Model. In contrast with deep inelastic eP-scattering (e + p → e + X), where the choice of Q2, as the transferred momentum squared, is unambiguous; whereas in the case of boson production , the transferred momentum squared, at quark level, depends on the reaction mechanism (where is the EW interaction taking place). We suggest a proposal based on kinematics of the process considered and the usual criterion for Q2 , which leads to a simple and practical prescription to calculate Z-production via ep-DIS. We also introduce different options in order o perform the convolution of the parton distribution functions (PDFs) and the scattering amplitude of he quark processes. Our aim in this work is to analyze and show how large could be the dependence of the total cross section rates on different possible prescriptions used for the identification of the scale energy parameter Q2 . We present results for the total cross section as a function of the total energy √s of the system ep, in the range 300 <√s ≤ 1300 Ge

    Overcoming triple-negative breast cancer (TNBC) resistance to oncolytic virotherapy by histone deacetylase inhibitor, trichostatin A

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    "Triple-negative breast cancer (TNBC) is a tumor classification that lack receptors for the hormones estrogen, progesterone and HER2 protein. These malignancies are characterized to be of poor prognosis, refractoriness to conventional therapy and high rates of recurrence. Virotherapy with oncolytic adenovirus (OAd) consists of cancer selective viruses that replicate, spread, and kill cancer cells by oncolysis, without affecting the normal cells."--Introduction

    The Quantity of Intracluster Light: Comparing Theoretical and Observational Measurement Techniques Using Simulated Clusters

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    Using a suite of N-body simulations of galaxy clusters specifically tailored to study the intracluster light (ICL) component, we measure the quantity of ICL using a number of different methods previously employed in the literature for both observational and simulation data sets. By measuring the ICL of the clusters using multiple techniques, we identify systematic differences in how each detection method identifies the ICL. We find that techniques which define the ICL solely based on the current position of the cluster luminosity, such as a surface brightness or local density threshold, tend to find less ICL than methods utilizing time or velocity information, including stellar particles' density history or binding energy. The range of ICL fractions (the fraction of the clusters' total luminosity found in the ICL component) we measure at z=0 across all our clusters using any definition span the range from 9-36%, and even within a single cluster different methods can change the measured ICL fraction by up to a factor of two. Separating the cluster's central galaxy from the surrounding ICL component is a challenge for all ICL techniques, and because the ICL is centrally concentrated within the cluster, the differences in the measured ICL quantity between techniques are largely a consequence of this central galaxy/ICL separation. We thoroughly explore the free parameters involved with each measurement method, and find that adjusting these parameters can change the measured ICL fraction by up to a factor of two. While for all definitions the quantity of ICL tends to increase with time, the ICL fraction does not grow at a uniform rate, nor even monotonically under some definitions. Thus, the ICL can be used as a rough indicator of dynamical age, where more dynamically advanced clusters will on average have higher ICL fractions.Comment: 18 pages, 11 figues. Accepted for publication in Ap
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