965 research outputs found
Monitoring methane emission of mud volcanoes by seismic tremor measurements: a pilot study
Abstract. A new approach for estimating methane emission at mud volcanoes is here proposed based on measurements of the seismic tremor on their surface. Data obtained at the Dashgil mud volcano in Azerbaijan reveal the presence of energy bursts characterized by well-determined features (i.e. waveforms, spectra and polarization properties) that can be associated with bubbling at depth. Counting such events provides a possible tool for monitoring gas production in the reservoir, thus minimizing logistic troubles and representing a cheap and effective alternative to more complex approaches. Specifically, we model the energy bursts as the effect of resonant gas bubbles at depth. This modelling allows to estimate the dimension of the bubbles and, consequently, the gas outflow from the main conduit in the assumption that all emissions from depth occur by bubble uprising. The application of this model to seismic events detected at the Dashgil mud volcano during three sessions of measurements carried out in 2006 and 2007 provides gas flux estimates that are in line with those provided by independent measurements at the same structure. This encouraging result suggests that the one here proposed could be considered a new promising, cheap and easy to apply tool for gas flux measurements in bubbling gas seepage areas
Safety Considerations in the Ground Environment
In the history of humankind, every great space adventure has begun on the ground. While this seems to be stating the obvious, mission and spacecraft designers who have overlooked this fact have paid a high price, either in loss or damage to the spacecraft pre-launch, or in mission failure or reduction. Spacecraft personnel may risk not only their flight hardware, but they may also risk their lives, their co-workers lives and even the general public by not heeding safety on the ground. Their eyes may be on the stars but their feet are on the ground! One additional comment: Although the design requirements are very different for human rated and nonhuman rated flight hardware, while on the ground that flight hardware (and its ground support equipment) doesn't care about what it is flying on. On the ground, additional requirements are often levied to protect the work force and general public. (Authors' Note: The source material for this chapter is primarily taken from the Kennedy Space Center Handbook (KHB) 1700.7/45 SW Handbook S-100 Space Shuttle Payload Ground Safety Handbook and the authors' personal experiences
Evidence of Luttinger liquid behavior in one-dimensional dipolar quantum gases
The ground state and structure of a one-dimensional Bose gas with dipolar
repulsions is investigated at zero temperature by a combined Reptation Quantum
Monte Carlo (RQMC) and bosonization approach. A non trivial Luttinger-liquid
behavior emerges in a wide range of intermediate densities, evolving into a
Tonks-Girardeau gas at low density and into a classical quasi-ordered state at
high density. The density dependence of the Luttinger exponent is extracted
from the numerical data, providing analytical predictions for observable
quantities, such as the structure factor and the momentum distribution. We
discuss the accessibility of such predictions in current experiments with
ultracold atomic and molecular gases.Comment: 4 pages, 3 EPS figures, Revtex
Collective excitations of trapped one-dimensional dipolar quantum gases
We calculate the excitation modes of a 1D dipolar quantum gas confined in a
harmonic trap with frequency and predict how the frequency of the
breathing n=2 mode characterizes the interaction strength evolving from the
Tonks-Girardeau value to the quasi-ordered, super-strongly
interacting value . Our predictions are obtained
within a hydrodynamic Luttinger-Liquid theory after applying the Local Density
Approximation to the equation of state for the homogeneous dipolar gas, which
are in turn determined from Reptation Quantum Monte Carlo simulations. They are
shown to be in quite accurate agreement with the results of a sum-rule
approach. These effects can be observed in current experiments, revealing the
Luttinger-liquid nature of 1D dipolar Bose gases.Comment: 5 pages, 2 EPS figures, RevTeX
The Revised Identity Style Inventory: Factor Structure and Validity in Italian Speaking Students
The purpose of this study was to evaluate the factor structure and convergent and discriminant validity of scores on an Italian translation of the Revised Identity Style Inventory (ISI-5) with samples of 237 adolescents (50 males, Mage = 18.04, SD = .86) and 268 university students (42 males, Mage = 22.71, SD = 3.70). Confirmatory Factor Analysis indicated that a three-factor solution provided a good fit, which was invariant across age and sex groups. The theoretically relationships between scores on the ISI and scores on measures of reasoning and identity processes, identity commitment, and social desirability were partially consistent, thus further studies are needed to give more evidence to the convergent and discriminant validity
Validation of the Internet Gaming Disorder Scale - Short-Form (IGDS9-SF) in an Italian-speaking sample
Background and aims: The inclusion of Internet Gaming Disorder (IGD) in Section III of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders has increased the interest of researchers in the development of new standardized psychometric tools for the assessment of such a disorder. To date, the nine-item Internet Gaming Disorder Scale - Short-Form (IGDS9-SF) has only been validated in English, Portuguese, and Slovenian languages. Therefore, the aim of this investigation was to examine the psychometric properties of the IGDS9-SF in an Italian-speaking sample. Methods: A total of 757 participants were recruited to the present study. Confirmatory factor analysis and multi-group analyses were applied to assess the construct validity. Reliability analyses comprised the average variance extracted, the standard error of measurement, and the factor determinacy coefficient. Convergent and criterion validities were established through the associations with other related constructs. The receiver operating characteristic curve analysis was used to determine an empirical cut-off point. Results: Findings confirmed the singlefactor structure of the instrument, its measurement invariance at the configural level, and the convergent and criterion validities. Satisfactory levels of reliability and a cut-off point of 21 were obtained. Discussion and conclusions: The present study provides validity evidence for the use of the Italian version of the IGDS9-SF and may foster research into gaming addiction in the Italian context
A comparison of optical and radar measurements of mesospheric winds and tides
Optical measurements of mesospheric winds by Fabry‐Perot spectrometers, FPSs, at Mawson, 67.6°S 62.9°E, and Davis, 68.6°S 78.0°E, Antarctica are compared with similar measurements obtained using a spaced‐antenna MF radar at Davis. The FPSs observed the OH emission. Different analysis procedures, used to determine the mean wind, and amplitude and phase of the semidiurnal tide, have been compared. At these latitudes the diurnal tide is weak and the semi‐diurnal tide, although highly variable in amplitude, is usually the dominant periodicity. When comparing the amplitude and phase of the semidiurnal tide good agreement is obtained between measurements by the two instruments
Nonmigrating semidiurnal tide over the Arctic determined from TIMED Doppler Interferometer wind observations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94847/1/jgrd15899.pd
- …