2,101 research outputs found

    Nanocarriers for topical delivery of resveratrol.

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    Purpose: The aim of the present work was to develop a nanocarrier-based formulation for topical delivery of resveratrol. Methods: Trans-resveratrol (t-res) was encapsulated in liposomes, ethosomes or transferosomes, by a modified hand-shaking method followed by extrusion. All the formulations were characterised in terms of mean diameter, size distribution (I.P.), t-res loading, t-res stability upon encapsulation during storage. The nanocarriers containing t-res were then introduced in cellulose-based gel to allow their final administration on the skin and the viscoelastic properties of the resulting formulation were investigated. Finally, we studied the inhibition of reactive oxygen species (ROS) in human keratinocyte (HaCaT) cell line stimulated with H2O2 for 24 h and then incubated with the t-res containing nanocarriers. Results: All the t-res containing carriers were characterised by a very high (close to 100%) encapsulation efficiency, a negligible t-res release at 4°C and stability of resveratrol in its trans form. The carriers only slightly influenced the viscoelastic characteristics of cellulose-based gels. Nanocarriers encapsulating t-res reduced, in a concentration-dependent manner, ROS production induced by H2O2 and this effect was higher when using t-res-encapsulating nanocarrier, with the higher effect observed in the case of ethosomes. Conclusions: In this work nanocarriers with high encapsulation efficiency, high physical stability and negligible t-res release during storage at 4°C were prepared. To allow their final administration on the skin, the nanocarrier can be easilisy loaded in cellulose-based gels without altering its rheological properties. Moreover, the use of t-res-encapsulating ethosomes led to an efficient antioxidant activity. Further ex vivo and in vivo studies will clarify the role of the different carrier when administered on the skin

    Dual-readout Calorimetry

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    The RD52 Project at CERN is a pure instrumentation experiment whose goal is to understand the fundamental limitations to hadronic energy resolution, and other aspects of energy measurement, in high energy calorimeters. We have found that dual-readout calorimetry provides heretofore unprecedented information event-by-event for energy resolution, linearity of response, ease and robustness of calibration, fidelity of data, and particle identification, including energy lost to binding energy in nuclear break-up. We believe that hadronic energy resolutions of {\sigma}/E \approx 1 - 2% are within reach for dual-readout calorimeters, enabling for the first time comparable measurement preci- sions on electrons, photons, muons, and quarks (jets). We briefly describe our current progress and near-term future plans. Complete information on all aspects of our work is available at the RD52 website http://highenergy.phys.ttu.edu/dream/.Comment: 10 pages, 10 figures, Snowmass White pape

    Dual-Readout Calorimetry with Lead Tungstate Crystals

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    Results are presented of beam tests in which a small electromagnetic calorimeter consisting of lead tungstate crystals was exposed to 50 GeV electrons and pions. This calorimeter was backed up by the DREAM Dual-Readout calorimeter, which measures the scintillation and \v{C}erenkov light produced in the shower development, using two different media. The signals from the crystal calorimeter were analyzed in great detail in an attempt to determine the contributions from these two types of light to the signals, event by event. This information makes it possible to eliminate the dominating source of fluctuations and thus achieve an important improvement in hadronic calorimeter performance.Comment: Preprint submitted to Nucl. Instrum. Meth. on July 23, 200

    Production properties of K*(892) vector mesons and their spin alignment as measured in the NOMAD experiment

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    First measurements of K*(892) mesons production properties and their spin alignment in nu_mu charged current (CC) and neutral current (NC) interactions are presented. The analysis of the full data sample of the NOMAD experiment is performed in different kinematic regions. For K*+ and K*- mesons produced in nu_mu CC interactions and decaying into K0 pi+/- we have found the following yields per event: (2.6 +/- 0.2 (stat.) +/- 0.2 (syst.))% and (1.6 +/- 0.1 (stat.) +/- 0.1 (syst.))% respectively, while for the K*+ and K*- mesons produced in nu NC interactions the corresponding yields per event are: (2.5 +/- 0.3 (stat.) +/- 0.3 (syst.))% and (1.0 +/- 0.3 (stat.) +/- 0.2 (syst.))%. The results obtained for the rho00 parameter, 0.40 +/- 0.06 (stat) +/- 0.03 (syst) and 0.28 +/- 0.07 (stat) +/- 0.03 (syst) for K*+ and K*- produced in nu_mu CC interactions, are compared to theoretical predictions tuned on LEP measurements in e+e- annihilation at the Z0 pole. For K*+ mesons produced in nu NC interactions the measured rho00 parameter is 0.66 +/- 0.10 (stat) +/- 0.05 (syst).Comment: 20 p

    Search for the exotic Θ+\Theta^+ resonance in the NOMAD experiment

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    A search for exotic Theta baryon via Theta -> proton +Ks decay mode in the NOMAD muon neutrino DIS data is reported. The special background generation procedure was developed. The proton identification criteria are tuned to maximize the sensitivity to the Theta signal as a function of xF which allows to study the Theta production mechanism. We do not observe any evidence for the Theta state in the NOMAD data. We provide an upper limit on Theta production rate at 90% CL as 2.13 per 1000 of neutrino interactions.Comment: Accepted to European Physics Journal

    A Precise Measurement of the Muon Neutrino-Nucleon Inclusive Charged Current Cross-Section off an Isoscalar Target in the Energy Range 2.5 < E_\nu < 40 GeV by NOMAD

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    We present a measurement of the muon neutrino-nucleon inclusive charged current cross-section, off an isoscalar target, in the neutrino energy range 2.5Eν402.5 \leq E_\nu \leq 40 GeV. The significance of this measurement is its precision, ±4\pm 4% in 2.5Eν102.5 \leq E_\nu \leq 10 GeV, and ±2.6\pm 2.6% in 10Eν4010 \leq E_\nu \leq 40 GeV regions, where significant uncertainties in previous experiments still exist, and its importance to the current and proposed long baseline neutrino oscillation experiments.Comment: 14 pages, 3 figures, submitted to Phys.Lett.

    Search for nu(mu)-->nu(e) Oscillations in the NOMAD Experiment

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    We present the results of a search for nu(mu)-->nu(e) oscillations in the NOMAD experiment at CERN. The experiment looked for the appearance of nu(e) in a predominantly nu(mu) wide-band neutrino beam at the CERN SPS. No evidence for oscillations was found. The 90% confidence limits obtained are delta m^2 < 0.4 eV^2 for maximal mixing and sin^2(2theta) < 1.4x10^{-3} for large delta m^2. This result excludes the LSND allowed region of oscillation parameters with delta m^2 > 10 eV^2.Comment: 19 pages, 8 figures. Submitted to Phys. Lett.

    A Study of Strange Particles Produced in Neutrino Neutral Current Interactions in the NOMAD Experiment

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    Results of a detailed study of strange particle production in neutrino neutral current interactions are presented using the data from the NOMAD experiment. Integral yields of neutral strange particles (K0s, Lambda, Lambda-bar) have been measured. Decays of resonances and heavy hyperons with an identified K0s or Lambda in the final state have been analyzed. Clear signals corresponding to K* and Sigma(1385) have been observed. First results on the measurements of the Lambda polarization in neutral current interactions have been obtained.Comment: Accepted for publication in Nuclear Physics B as a rapid communicatio

    Final NOMAD results on nu_mu->nu_tau and nu_e->nu_tau oscillations including a new search for nu_tau appearance using hadronic tau decays

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    Results from the nu_tau appearance search in a neutrino beam using the full NOMAD data sample are reported. A new analysis unifies all the hadronic tau decays, significantly improving the overall sensitivity of the experiment to oscillations. The "blind analysis" of all topologies yields no evidence for an oscillation signal. In the two-family oscillation scenario, this sets a 90% C.L. allowed region in the sin^2(2theta)-Delta m^2 plane which includes sin^2(2theta)<3.3 x 10^{-4} at large Delta m^2 and Delta m^2 < 0.7 eV^2/c^4 at sin^2(2theta)=1. The corresponding contour in the nu_e->nu_tau oscillation hypothesis results in sin^2(2theta)<1.5 x 10^{-2} at large Delta m^2 and Delta m^2 < 5.9 eV^2/c^4 at sin^2(2theta)=1. We also derive limits on effective couplings of the tau lepton to nu_mu or nu_e.Comment: 46 pages, 16 figures, Latex, to appear on Nucl. Phys.

    A Measurement of Coherent Neutral Pion Production in Neutrino Neutral Current Interactions in NOMAD

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    We present a study of exclusive neutral pion production in neutrino-nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to 1.44×1061.44 \times 10^6 muon-neutrino Charged Current interactions in the energy range 2.5Eν3002.5 \leq E_{\nu} \leq 300 GeV. Neutrino events with only one visible π0\pi^0 in the final state are expected to result from two Neutral Current processes: coherent π0\pi^0 production, {\boldmath ν+Aν+A+π0\nu + {\cal A} \to \nu + {\cal A} + \pi^0} and single π0\pi^0 production in neutrino-nucleon scattering. The signature of coherent π0\pi^0 production is an emergent π0\pi^0 almost collinear with the incident neutrino while π0\pi^0's produced in neutrino-nucleon deep inelastic scattering have larger transverse momenta. In this analysis all relevant backgrounds to the coherent π0\pi^0 production signal are measured using data themselves. Having determined the backgrounds, and using the Rein-Sehgal model for the coherent π0\pi^0 production to compute the detection efficiency, we obtain {\boldmath 4630±522(stat)±426(syst)4630 \pm 522 (stat) \pm 426 (syst)} corrected coherent-π0\pi^0 events with Eπ00.5E_{\pi^0} \geq 0.5 GeV. We measure {\boldmath σ(νAνAπ0)=[72.6±8.1(stat)±6.9(syst)]×1040cm2/nucleus\sigma (\nu {\cal A} \to \nu {\cal A} \pi^0) = [ 72.6 \pm 8.1(stat) \pm 6.9(syst) ] \times 10^{-40} cm^2/nucleus}. This is the most precise measurement of the coherent π0\pi^0 production to date.Comment: 23 pages, 9 figures, accepted for publication in Phys. Lett.
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