1,294 research outputs found
The Trigger System of the ARGO-YBJ detector
The ARGO-YBJ experiment has been designed to detect air shower events over a
large size scale and with an energy threshold of a few hundreds GeV. The
building blocks of the ARGO-YBJ detector are single-gap Resistive Plate
Counters (RPCs). The trigger logic selects the events on the basis of their hit
multiplicity. Inclusive triggers as well as dedicated triggers for specific
physics channels or calibration purposes have been developed. This paper
describes the architecture and the main features of the trigger system.Comment: 4 pages, to be published in the Proceedings of the 28th International
Cosmic Ray Conference (Tsukuba, Japan 2003
First in-situ sensing of volcanic gas plume composition at Boiling Lake (Dominica, West Indies)
Dominica, a small Caribbean island between Martinique (to the South) and
Guadeloupe (to the North), is, because of the high number of potentially active volcanic centres,one of the most susceptible sites to volcanic risk in the Lesser Antilles arc. Seven major volcanic centres, active during the last 10ka, are considered likely to erupt again, and one of these is the
Valley of Desolation volcanic complex. This is an area of 0.5 km2, located in on SW Dominica, where a number of small explosion craters, hot springs,bubbling pools and fumaroles testify for vigorous and persistent hydrothermal activity. Two main phreatic explosions have been documented in historical time (1880 and 1997), and the most likely centre of future activity is the
Boiling Lake, a nearby high-T volcanic crater lake produced by an undated phreatic/phreatomagmatic explosion. Hot (80 to 90\ub0C) and acidic (4-6) waters normally characterize the steady-state activity of the lake, whereby which vigorous gas upwelling in the lake\u2019s centre feeds a persistent steaming plume. Stability of the Boiling Lake has occasionally been interrupted in the
past (since 1876) by crises, the most recent in 2004, involving rapid draining of the lake and changes in water temperature and pH, likely as a result of drastic decrease of hydrothermal fluid input into the lake. While the chemical and isotopic composition of the lake waters is well
characterised, there are no compositional data available for the gas plume leaving the lake, due to
inherent difficulties in direct gas sampling. Here, we present the results of the first direct measurements of the Boiling Lake\u2019s plume, performed by using the MultiGAS technique in February 2012. We acquired 0.5 Hz time-series of H2O, CO2, H2S and SO2 plume concentrations,which were seen to peak (with maximum background-corrected concentrations of 3680, 101 and 25 ppm for respectively H2O, CO2 and H2S) during phases of visible increase in lake outgassing.
SO2 was virtually absent in the plume. From the concentration data, the characteristic CO2/H2S (5.2\ub10.4) and H2O/CO2 (31.4\ub16) volatile ratios in the Boiling lake\u2019s atmospheric plume were
derived. This reveals similar C to S signature for Boiling lake and Valley of Desolation (for which we also obtained data using the same technique), likely indicative of common source reservoir.
The Boiling lake\u2019s plume is far more H2O-rich than the Valley of Desolation gas, suggesting that a significant fraction of in-plume H2O in the former originates from re-evaporation of the lake water itself. Our data here provide a first compositional baseline for quiescent volcanic gas emissions at
Boiling Lake, and may form the basis to stimulate emerging geochemical monitoring programs in the area
Non-Fermi liquid behavior in transport through Co doped Au chains
We calculate the conductance as a function of temperature through Au
monoatomic chains containing one Co atom as a magnetic impurity, and connected
to two conducting leads with a 4-fold symmetry axis. Using the information
derived from {\it ab initio} calculations, we construct an effective model
\Heff that hybridizes a 3d quadruplet at the Co site with two 3d
triplets through the hopping of 5d and 5d electrons of Au. The
quadruplet is split by spin anisotropy due to spin-orbit coupling. Solving
\Heff with the numerical renormalization group (NRG) % Wb: reverted my own
change we find that at low temperatures and the ground
state impurity entropy is , a behavior similar to the two-channel
Kondo model. Stretching the chain leads to a non Kondo phase, with the physics
of the underscreened Kondo model at the quantum critical point.Comment: Accepted in Physical Review Letter
Unusual Kondo physics in a Co impurity atom embedded in noble-metal chains
We analyze the conduction bands of the one dimensional noble-metal chains
that contain a Co magnetic impurity by means of ab initio calculations. We
compare the results obtained for Cu and Ag pure chains, as well as O doped Cu,
Ag and Au chains with those previously found for Au pure chains. We find
similar results in the case of Cu and Au hosts, whereas for Ag chains a
different behavior is obtained. Differences and similarities among the
different systems are analyzed by comparing the electronic structure of the
three noble-metal hosts. The d-orbitals of Cu chains at the Fermi level have
the same symmetry as in the case of Au chains. These orbitals hybridize with
the corresponding ones of the Co impurity, giving rise to the possibility of
exhibiting a two-channel Kondo physics.Comment: Accepted in IEEE Trans. Magn. - April 201
Fractional differentiability for solutions of nonlinear elliptic equations
We study nonlinear elliptic equations in divergence form
When
has linear growth in , and assuming that enjoys smoothness, local
well-posedness is found in for certain values of
and . In the particular case
, and ,
, we obtain for each
. Our main tool in the proof is a more general result, that
holds also if has growth in , , and
asserts local well-posedness in for each , provided that
satisfies a locally uniform condition
Lipschitz regularity for degenerate elliptic integrals with p, q-growth
We establish the local Lipschitz continuity and the higher differentiability of vector-valued local minimizers of a class of energy integrals of the Calculus of Variations. The main novelty is that we deal with possibly degenerate energy densities with respect to the x -variable
RETRACTION of the paper: About some issues concerning shape memory alloys application s in neuro-rehabilitation, METABK 59(1) (2020), 137-140.
RETRACTION NOTICE for the paper: About some issues concerning shape memory alloys application s in neuro-rehabilitation, METABK 59(1) (2020), 137-140
SAR data and field surveys combination to update rainfall-induced shallow landslide inventory
The Campania region has been recurrently hit by severe landslides in volcanoclastic deposits. The city of Naples, and in particular the Camaldoli and Agnano hills (Phlegraean Fields), also suffered several landslide crises in weathered volcanoclastic rocks as a consequence of intense rainfalls or wildfires. To identify slope failures phenomena occurred in the winter season 2019–2020 an innovative procedure has been proposed. The purpose of this procedure is to highlight areas where major land cover changes occurred within our area of study, which can be potentially related to mass movements. The amplitude of spaceborne SAR images has been exploited for the change detection analysis and the output derived from the segmentation procedure has been compared with field observations. The amplitude-based method has been already applied in the detection of landslides, but never on the event with limited extensions, such as for this application. The achieved outcomes allowed the mapping of 62 new landslides that have been used to update the current landslide inventory database. This type of information is expected to help decision-makers with land planning and risk assessment
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