4,815 research outputs found
Reinforcement in seismic design of masonry structures
The article deals with the basic considerations to be kept in mind when designing "simple buildings" built with masonries which can be exposed to seismic vibrations. The influence of so usual "confined masonries" on the seismic wave is also analyzed. These masonries are actually reticulate frames with masonry panels filling them. After analyzing mechanisms of failures in masonry buildings exposed to earthquake, the article concentrates on the layout of reinforcements which can diminish seismic effects
Seismic Vulnerability of the Italian Roadway Bridge Stock
This study focuses on the seismic vulnerability evaluation of the Italian roadway bridge stock, within the framework of a Civil Protection sponsored project. A comprehensive database of existing bridges (17,000 bridges with different level of knowledge) was implemented. At the core of the study stands a procedure for automatically carrying out state-of-the-art analytical evaluation of fragility curves for two performance levels – damage and collapse – on an individual bridge basis. A webGIS was developed to handle data and results. The main outputs are maps of bridge seismic risk (from the fragilities and the hazard maps) at the national level and real-time scenario damage-probability maps (from the fragilities and the scenario shake maps). In the latter case the webGIS also performs network analysis to identify routes to be followed by rescue teams. Consistency of the fragility derivation over the entire bridge stock is regarded as a major advantage of the adopted approach
Bright submillimeter galaxies do trace galaxy protoclusters
There is controversy whether dusty starbursts selected at submillimeter
wavelengths can trace galaxy overdensities. We perform the first systematic
search for protoclusters around a homogeneously selected sample of 12
spectroscopically confirmed submillimeter galaxies (SMGs) at in
the GOODS-N field. We applied the Poisson Probability Method (PPM) to search
for Mpc scale overdensities around these SMGs using three photometric redshift
catalogs. We detect galaxy overdensities for 11 out of the 12 SMGs
(\%), distributed over eight protoclusters. We confirm three
previously discovered protoclusters, and we detect five new ones around the
SMGs SMMJ123634 (), ID.19 (), SMMJ123607 (),
SMMJ123606 (), and GN10 (). A wavelet-based analysis shows
that the SMGs live in protocluster cores with a complex morphology (compact,
filamentary, or clumpy) and an average size of Mpc. By comparing
the PPM results obtained using independently the three redshift catalogs, we
possibly witness a transitioning phase at for the galaxy
populations. While protoclusters appear to be populated by dusty
galaxies, those at highest redshifts are detected as overdensities of
Lyman emitters or Lyman break galaxies. We also find a good correlation
between the molecular (H) gas mass of the SMG and the overdensity
significance. To explain the overall phenomenology, we suggest that galaxy
interactions in dense environments likely triggered the starburst and gas-rich
phase of the SMGs. Altogether, we support the scenario that SMGs are excellent
tracers of distant protoclusters. Those presented in this work are excellent
targets for the {\it James Webb Space Telescope.} Surveys with forthcoming
facilities (e.g., {\it Euclid}, LSST) can be tuned to detect even larger
samples of distant protoclusters.Comment: 22 pages, Astronomy & Astrophysics in press. HTML files of Figure 3
are available at https://obswww.unige.ch/~castigna/Figure3_html
Constraining CP violation in neutral meson mixing with theory input
There has been a lot of recent interest in the experimental hints of CP
violation in B_{d,s}^0 mixing, which would be a clear signal of beyond the
standard model physics (with higher significance). We derive a new relation for
the mixing parameters, which allows clearer interpretation of the data in
models in which new physics enters in M_12 and/or \Gamma_12. Our results imply
that the central value of the D\O\ measurement of the semileptonic CP asymmetry
in B_{d,s}^0 decay is not only in conflict with the standard model, but in a
stronger tension with data on \Delta\Gamma_s than previously appreciated. This
result can be used to improve the constraint on \Delta\Gamma or A_SL, whichever
is less precisely measured.Comment: 5 pages, 2 figures, informed of prior derivation of eq. (21), title
modifie
Characterization of the Hamamatsu R11265-103-M64 multi-anode photomultiplier tube
The aim of this paper is to fully characterize the new multi-anode
photomultiplier tube R11265-103-M64, produced by Hamamatsu. Its high effective
active area (77%), its pixel size, the low dark signal rate and the capability
to detect single photon signals make this tube suitable for an application in
high energy physics, such as for RICH detectors. Four tubes and two different
bias voltage dividers have been tested. The results of a standard
characterization of the gain and the anode uniformity, the dark signal rate,
the cross-talk and the device behaviour as a function of temperature have been
studied. The behaviour of the tube is studied in a longitudinal magnetic field
up to 100 Gauss. Shields made of a high permeability material are also
investigated. The deterioration of the device performance due to long time
operation at intense light exposure is studied. A quantitative analysis of the
variation of the gain and the dark signals rate due to the aging is described.Comment: 22 page
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