Influence of particle density on flow behavior and deposit architecture of concentrated pyroclastic density currents over a break in slope: Insights from laboratory experiments

Geological granular flows are highly complex, gravity-driven phenomena whose different behaviors depend on the mechanical properties, density and granulometric distributions of the constituent materials. Years of research have produced significant advances in understanding transport and deposition processes in granular flows. However, the role and effects of clast densities and density contrast in a granular flow are still not fully understood. In this paper we show the effect that pumice has on dry granular flows; specifically on flow velocity and longitudinal segregation of the deposits. Our work confirms, by experimental results, field observations on pumice/lithic segregation and longer pumice runout. We report results of velocity decay and deposit architecture for a granular flow passing over a break in slope (from 38° to 4° inclination). The 30 experimental runs were carried out in a five-meter long laboratory flume equipped with a series of sensors that include laser gates and high-speed cameras (400 fps). We used two polydisperse mixtures of dacitic lithics and rhyolitic pumice in varying amounts, with Weibull and Gaussian particle size distributions. The pumice/lithic ratio changes the flow response passing over a break in slope. This effect is particularly evident starting from 10% of pumice volume into the flow mixture, independently of its granulometric distribution. Runout relates to mass following a power law, with an exponent close 0.2. The experiments confirm that pumice segregation affects polydispersed mixtures, similarly to what has been observed in real field deposits, where density decoupling produces lithic-enriched proximal areas and pumice-enriched distal areas. The results obtained prove that the presence of low-density materials in a dense granular flow has a strong influence on its behavior

Functionalized up conversion rare earth nanoparticles for bio imaging of cancer cells

In recent yearsupconversion nanoparticles (UCNPs)have being investigated due to their potential applications in biomedicine such as fluorescent biolabels, among many others. The luminescence of this kind of NP's are effectively activatedby near infrared radiation (NIR) and upconvertto luminescence in the visible region. Besides, their luminescence is not faded as compared with organic dyes and fluorescent proteins. In this study, UCNPs made of Y2O3:Yb3+, Er3+ (1%, 10% mol) and Gd2O3:Yb3+, Er3+ (1%, 10% mol) were functionalized with aminosilanes and folic acid (UCNP-NH2-FA) and characterized with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and luminescence measurements. Moreover, cytotoxicity was analyzed via colorimetric assays MTT (methy-134 thiazolyltetrazolium) in two cancer cell lines: cervical adenocarcinoma cells (HeLa) and breast cancer cells MB-MDA-231. It is found that the functionalized UCNPs were non-cytotoxic in all cancer cell lines. Confocal images revealed that UCNP-NH2-FA conjugates as a target to attract cells with overexpressed folate receptor (FR). The UCNPs offer a great potential to be used as bio labels because their fluorescence was clearly localized into cell cytoplasm

Results of the engineering run of the coherent neutrino nucleus interaction experiment (CONNIE)

The CONNIE detector prototype is operating at a distance of 30 m from the core of a 3.8 GWth nuclear reactor with the goal of establishing Charge-Coupled Devices (CCD) as a new technology for the detection of coherent elastic neutrino-nucleus scattering. We report on the results of the engineering run with an active mass of 4 g of silicon. The CCD array is described, and the performance observed during the first year is discussed. A compact passive shield was deployed around the detector, producing an order of magnitude reduction in the background rate. The remaining background observed during the run was stable, and dominated by internal contamination in the detector packaging materials. The in-situ calibration of the detector using X-ray lines from fluorescence demonstrates good stability of the readout system. The event rates with the reactor ON and OFF are compared, and no excess is observed coming from nuclear fission at the power plant. The upper limit for the neutrino event rate is set two orders of magnitude above the expectations for the standard model. The results demonstrate the cryogenic CCD-based detector can be remotely operated at the reactor site with stable noise below2 e RMS and stable background rates. The success of the engineering test provides a clear path for the upgraded 100 g detector to be deployed during 2016.Fil: Aguilar Arevalo, A.. Universidad Nacional Autónoma de México; MéxicoFil: Bertou, Xavier Pierre Louis. Comisión Nacional de Energía Atómica; Argentina. Comisión Nacional de Energía Atómica. Fundación José A. Balseiro; ArgentinaFil: Bonifazi, C.. Universidade Federal do Rio de Janeiro; BrasilFil: Butner, M.. Fermi National Accelerator Laboratory; Estados UnidosFil: Cancelo, G.. Fermi National Accelerator Laboratory; Estados UnidosFil: Castañeda Vazquez, A.. Universidad Nacional Autónoma de México; MéxicoFil: Cervantes Vergara, B.. Universidad Nacional Autónoma de México; MéxicoFil: Chavez, C. R.. Universidad Nacional de Asunción; ParaguayFil: Da Motta, H.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: D'Olivo, J. C.. Universidad Nacional Autónoma de México; MéxicoFil: Dos Anjos, J.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Estrada, J.. Fermi National Accelerator Laboratory; Estados UnidosFil: Fernández Moroni, Guillermo. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ford, R.. Fermi National Accelerator Laboratory; Estados UnidosFil: Foguel, A.. Centro Brasileiro de Pesquisas Físicas; Brasil. Universidade Federal do Rio de Janeiro; BrasilFil: Hernandez Torres, K. P.. Universidad Nacional Autónoma de México; MéxicoFil: Izraelevitch, F.. Fermi National Accelerator Laboratory; Estados UnidosFil: Kavner, A.. University of Michigan; Estados UnidosFil: Kilminster, B.. Universitat Zurich; SuizaFil: Kuk, K.. Fermi National Accelerator Laboratory; Estados UnidosFil: Lima Jr, H. P.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Makler, M.. Centro Brasileiro de Pesquisas Físicas; BrasilFil: Molina, J.. Universidad Nacional de Asunción; ParaguayFil: Moreno Granados, G.. Universidad Nacional Autónoma de México; MéxicoFil: Moro, Juan Manuel. Universidad Nacional del Sur. Departamento de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Paolini, Eduardo Emilio. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto ; ArgentinaFil: Sofo Haro, Miguel Francisco. Comision Nacional de Energia Atomica. Gerencia D/area de Energia Nuclear; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tiffenberg, Javier Sebastian. Fermi National Accelerator Laboratory; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Trillaud, F.. Universidad Nacional Autónoma de México; MéxicoFil: Wagner, S.. Centro Brasileiro de Pesquisas Físicas; Brasil. Pontificia Universidade Católica do Rio Grande do Sul; Brasi

A search for point sources of EeV photons

Measurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been detected. An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit that results from this, assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical Journa

Reconstruction of inclined air showers detected with the Pierre Auger Observatory

We describe the method devised to reconstruct inclined cosmic-ray air showers with zenith angles greater than $60^\circ$ detected with the surface array of the Pierre Auger Observatory. The measured signals at the ground level are fitted to muon density distributions predicted with atmospheric cascade models to obtain the relative shower size as an overall normalization parameter. The method is evaluated using simulated showers to test its performance. The energy of the cosmic rays is calibrated using a sub-sample of events reconstructed with both the fluorescence and surface array techniques. The reconstruction method described here provides the basis of complementary analyses including an independent measurement of the energy spectrum of ultra-high energy cosmic rays using very inclined events collected by the Pierre Auger Observatory.Comment: 27 pages, 19 figures, accepted for publication in Journal of Cosmology and Astroparticle Physics (JCAP

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7 TeV with the ATLAS detector

The production of a W boson in association with a single charm quark is studied using 4.6 fb−1 of pp collision data at s√ = 7 TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+0.26−0.30 at Q 2 = 1.9 GeV2, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally, the cross-section ratio σ(W + +c¯¯)/σ(W − + c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s−s¯¯¯ quark asymmetry