30 research outputs found
VAMOS: a Pathfinder for the HAWC Gamma-Ray Observatory
VAMOS was a prototype detector built in 2011 at an altitude of 4100m a.s.l.
in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design,
construction techniques and data acquisition system of the HAWC observatory.
HAWC is an air-shower array currently under construction at the same site of
VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water
Cherenkov detectors and two different data acquisition systems. It was in
operation between October 2011 and May 2012 with an average live time of 30%.
Besides the scientific verification purposes, the eight months of data were
used to obtain the results presented in this paper: the detector response to
the Forbush decrease of March 2012, and the analysis of possible emission, at
energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B.Comment: Accepted for pubblication in Astroparticle Physics Journal (20 pages,
10 figures). Corresponding authors: A.Marinelli and D.Zaboro
The Love of Money and Pay Level Satisfaction: Measurement and Functional Equivalence in 29 Geopolitical Entities around the World
Demonstrating the equivalence of constructs is a key requirement for cross-cultural empirical research. The major purpose of this paper is to demonstrate how to assess measurement and functional equivalence or invariance using the 9-item, 3-factor Love of Money Scale (LOMS, a second-order factor model) and the 4-item, 1-factor Pay Level Satisfaction Scale (PLSS, a first-order factor model) across 29 samples in six continents (N = 5973). In step 1, we tested the configural, metric and scalar invariance of the LOMS and 17 samples achieved measurement invariance. In step 2, we applied the same procedures to the PLSS and nine samples achieved measurement invariance. Five samples (Brazil, China, South Africa, Spain and the USA) passed the measurement invariance criteria for both measures. In step 3, we found that for these two measures, common method variance was non-significant. In step 4, we tested the functional equivalence between the Love of Money Scale and Pay Level Satisfaction Scale. We achieved functional equivalence for these two scales in all five samples. The results of this study suggest the critical importance of evaluating and establishing measurement equivalence in cross-cultural studies. Suggestions for remedying measurement non-equivalence are offered
On the sensitivity of the HAWC observatory to gamma-ray bursts
We present the sensitivity of HAWC to Gamma Ray Bursts (GRBs). HAWC is a very
high-energy gamma-ray observatory currently under construction in Mexico at an
altitude of 4100 m. It will observe atmospheric air showers via the water
Cherenkov method. HAWC will consist of 300 large water tanks instrumented with
4 photomultipliers each. HAWC has two data acquisition (DAQ) systems. The main
DAQ system reads out coincident signals in the tanks and reconstructs the
direction and energy of individual atmospheric showers. The scaler DAQ counts
the hits in each photomultiplier tube (PMT) in the detector and searches for a
statistical excess over the noise of all PMTs. We show that HAWC has a
realistic opportunity to observe the high-energy power law components of GRBs
that extend at least up to 30 GeV, as it has been observed by Fermi LAT. The
two DAQ systems have an energy threshold that is low enough to observe events
similar to GRB 090510 and GRB 090902b with the characteristics observed by
Fermi LAT. HAWC will provide information about the high-energy spectra of GRBs
which in turn could help to understanding about e-pair attenuation in GRB jets,
extragalactic background light absorption, as well as establishing the highest
energy to which GRBs accelerate particles
Micromechanical Properties of Injection-Molded Starch–Wood Particle Composites
The micromechanical properties of injection molded starch–wood particle composites were investigated as a function of particle content and humidity conditions.
The composite materials were characterized by scanning electron microscopy and X-ray diffraction methods. The microhardness
of the composites was shown to increase notably with the concentration of the wood particles. In addition,creep behavior under the indenter and temperature dependence
were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density
and weight uptake of the injection-molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that
the wood in the starch composites did not prevent water loss from the samples.Peer reviewe
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
The love of money is the root of all evil: Pay satisfaction and cpi as moderators
By incorporating pay satisfaction at Level 1 and Corruption Perceptions Index (CPI) at Level 2, we investigated the relationship between the love of money and self-reported corrupt intent among 6,382 managers in 31 geopolitical entities across six continents. Our significant cross-level three-way interaction effect showed that for managers with high pay satisfaction, the intensity (slope) of the love of money to corrupt intent relationship was almost identical in high or low CPI entities but the former had the lowest magnitude of corrupt intent, whereas the latter had the highest. For those with low pay satisfaction, the slope was the steepest in high CPI entities, but was flat in the low CPI entities and the difference between the two was significant
The Love of Money and Pay Level Satisfaction: Measurement and Functional Equivalence in 29 Geopolitical Entities around the World
Demonstrating the equivalence of constructs is a key requirement for crosscultural
empirical research. The major purpose of this paper is to demonstrate how to
assess measurement and functional equivalence or invariance using the 9-item, 3-factor
Love of Money Scale (LOMS, a second-order factor model) and the 4-item, 1-factor Pay
Level Satisfaction Scale (PLSS, a first-order factor model) across 29 samples in six
continents (N = 5973). In step 1, we tested the configural, metric and scalar invariance
of the LOMS and 17 samples achieved measurement invariance. In step 2, we applied
the same procedures to the PLSS and nine samples achieved measurement invariance.
Five samples (Brazil, China, South Africa, Spain and the USA) passed the measurement
invariance criteria for both measures. In step 3, we found that for these two measures,
common method variance was non-significant. In step 4, we tested the functional
equivalence between the Love of Money Scale and Pay Level Satisfaction Scale. We
achieved functional equivalence for these two scales in all five samples. The results of
this study suggest the critical importance of evaluating and establishing measurement
equivalence in cross-cultural studies. Suggestions for remedying measurement nonequivalence
are offered