1,292 research outputs found

    1.65 micrometers (H-band) surface photometry of galaxies. III: observations of 558 galaxies with the TIRGO 1.5m telescope

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    We present near-infrared H-band (1.65 micron) surface photometry of 558 galaxies in the Coma Supercluster and in the Virgo cluster. This data set, obtained with the Arcetri NICMOS3 camera ARNICA mounted on the Gornergrat Infrared Telescope, is aimed at complementing, with observations of mostly early-type objects, our NIR survey of spiral galaxies in these regions, presented in previous papers of this series. Magnitudes at the optical radius, total magnitudes, isophotal radii and light concentration indices are derived. We confirm the existence of a positive correlation between the near-infrared concentration index and the galaxy H-band luminosity. (Tables 1 and 2 are only available in electronic form upon request to [email protected])Comment: 12 pages, 6 figures. Accepted for publication in A&A

    Circumferential buckling of a hydrogel tube emptying upon dehydration

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    A cylindrical hydrogel tube, completely submerged in water, hydrates by swelling and filling its internal cavity. When it comes back into contact with air, it dehydrates: the tube thus expels the solvent through the walls, shrinking. This dehydration process causes a depression in the tube cavity, which can lead to circumferential buckling. Here we study the occurrence of such buckling using a continuous model that combines nonlinear elasticity with Flory-Rehner theory, to take into account both the large deformations and the active behaviour of the hydrogel. In quasi-static approximation, we use the incremental deformation formalism, extended to the chemo-mechanical equations, to determine the threshold value of the enclosed volume at which buckling is triggered. This critical value is found to depend on the shell thickness, chemical potential and constitutive features. The results obtained are in good agreement with the results of the finite element simulations of the complete dynamic problem

    Oscillations of solar atmosphere neutrinos

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    The Sun is a source of high energy neutrinos (E > 10 GeV) produced by cosmic ray interactions in the solar atmosphere. We study the impact of three-flavor oscillations (in vacuum and in matter) on solar atmosphere neutrinos, and calculate their observable fluxes at Earth, as well as their event rates in a kilometer-scale detector in water or ice. We find that peculiar three-flavor oscillation effects in matter, which can occur in the energy range probed by solar atmosphere neutrinos, are significantly suppressed by averaging over the production region and over the neutrino and antineutrino components. In particular, we find that the relation between the neutrino fluxes at the Sun and at the Earth can be approximately expressed in terms of phase-averaged ``vacuum'' oscillations, dominated by a single mixing parameter (the angle theta_23).Comment: v2: 11 pages, 8 eps figures. Content added (Sec. III D and Fig. 6), references updated. Matches the published versio

    The TNG Near Infrared Camera Spectrometer

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    NICS (acronym for Near Infrared Camera Spectrometer) is the near-infrared cooled camera-spectrometer that has been developed by the Arcetri Infrared Group at the Arcetri Astrophysical Observatory, in collaboration with the CAISMI-CNR for the TNG (the Italian National Telescope Galileo at La Palma, Canary Islands, Spain). As NICS is in its scientific commissioning phase, we report its observing capabilities in the near-infrared bands at the TNG, along with the measured performance and the limiting magnitudes. We also describe some technical details of the project, such as cryogenics, mechanics, and the system which executes data acquisition and control, along with the related software.Comment: 7 pages, 5 figures, compiled with A&A macros. A&A in pres

    Unification of gravity, gauge fields, and Higgs bosons

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    We consider a diffeomorphism invariant theory of a gauge field valued in a Lie algebra that breaks spontaneously to the direct sum of the spacetime Lorentz algebra, a Yang-Mills algebra, and their complement. Beginning with a fully gauge invariant action -- an extension of the Plebanski action for general relativity -- we recover the action for gravity, Yang-Mills, and Higgs fields. The low-energy coupling constants, obtained after symmetry breaking, are all functions of the single parameter present in the initial action and the vacuum expectation value of the Higgs.Comment: 12 pages, no figures. v2 minor correction

    Probing non-standard decoherence effects with solar and KamLAND neutrinos

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    It has been speculated that quantum gravity might induce a "foamy" space-time structure at small scales, randomly perturbing the propagation phases of free-streaming particles (such as kaons, neutrons, or neutrinos). Particle interferometry might then reveal non-standard decoherence effects, in addition to standard ones (due to, e.g., finite source size and detector resolution.) In this work we discuss the phenomenology of such non-standard effects in the propagation of electron neutrinos in the Sun and in the long-baseline reactor experiment KamLAND, which jointly provide us with the best available probes of decoherence at neutrino energies E ~ few MeV. In the solar neutrino case, by means of a perturbative approach, decoherence is shown to modify the standard (adiabatic) propagation in matter through a calculable damping factor. By assuming a power-law dependence of decoherence effects in the energy domain (E^n with n = 0,+/-1,+/-2), theoretical predictions for two-family neutrino mixing are compared with the data and discussed. We find that neither solar nor KamLAND data show evidence in favor of non-standard decoherence effects, whose characteristic parameter gamma_0 can thus be significantly constrained. In the "Lorentz-invariant" case n=-1, we obtain the upper limit gamma_0<0.78 x 10^-26 GeV at 95% C.L. In the specific case n=-2, the constraints can also be interpreted as bounds on possible matter density fluctuations in the Sun, which we improve by a factor of ~ 2 with respect to previous analyses.Comment: Minor changes. Version accepted for publication in Phys. Rev.

    Cu-exchanged 3D-printed geopolymer/ZSM-5 monolith for selective catalytic reduction of NOx

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    Cu-exchanged zeolites with MFI structure, such as ZSM-5, represent effective catalysts for SCR processes when the application requires a good thermal stability under a wide range of temperature as for the after-treatment of exhaust gas from diesel engine. The production of zeolite in a structured form, mandatorily required for mobile applications, is quite complex due to the poor adhesion of the material. In this paper 3D-printed geopolymers containing about 37 % ZSM-5 are proposed as potentially structured catalysts for SCR applications. The production of the monolith and the pre-treatment necessary to introduce copper as active exchanged cation are investigated. The effect of pre-treatments on the physical and morphological structure of both geopolymer and zeolite and on the nature of copper introduced in the subsequent step was studied using characterization techniques such as SEM, XRD, N2 physisorption and Temperature Programmed Reduction (TPR)

    Day-night asymmetry of high and low energy solar neutrino events in Super-Kamiokande and in the Sudbury Neutrino Observatory

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    In the context of solar neutrino oscillations among active states, we briefly discuss the current likelihood of Mikheyev-Smirnov-Wolfenstein (MSW) solutions to the solar neutrino problem, which appear to be currently favored at large mixing, where small Earth regeneration effects might still be observable in Super-Kamiokande (SK) and in the Sudbury Neutrino Observatory (SNO). We point out that, since such effects are larger at high (low) solar neutrino energies for high (low) values of the mass square difference \delta m^2, it may be useful to split the night-day rate asymmetry in two separate energy ranges. We show that the difference \Delta of the night-day asymmetry at high and low energy may help to discriminate the two large-mixing solutions at low and high \delta m^2 through a sign test, both in SK and in SNO, provided that the sensitivity to \Delta can reach the (sub)percent level.Comment: 6 pages (RevTeX) + 4 figures (PostScript). Final version, to appear in Phys. Rev.

    Geometric Effects and Computation in Spin Networks

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    When initially introduced, a Hamiltonian that realises perfect transfer of a quantum state was found to be analogous to an x-rotation of a large spin. In this paper we extend the analogy further to demonstrate geometric effects by performing rotations on the spin. Such effects can be used to determine properties of the chain, such as its length, in a robust manner. Alternatively, they can form the basis of a spin network quantum computer. We demonstrate a universal set of gates in such a system by both dynamical and geometrical means

    Where we are on θ13\theta_{13}: addendum to "Global neutrino data and recent reactor fluxes: status of three-flavour oscillation parameters"

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    In this addendum to arXiv:1103.0734 we consider the recent results from long-baseline νμνe\nu_\mu\to\nu_e searches at the T2K and MINOS experiments and investigate their implications for the mixing angle θ13\theta_{13} and the leptonic Dirac CP phase δ\delta. By combining the 2.5σ2.5\sigma indication for a non-zero value of θ13\theta_{13} coming from T2K data with global neutrino oscillation data we obtain a significance for θ13>0\theta_{13} > 0 of about 3σ3\sigma with best fit points sin2θ13=0.013(0.016)\sin^2\theta_{13} = 0.013(0.016) for normal (inverted) neutrino mass ordering. These results depend somewhat on assumptions concerning the analysis of reactor neutrino data.Comment: 5 pages, 2 figures and 1 tabl
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