Search results for "Statistica"
showing 10 items of 5969 documents
GW190521: A Binary Black Hole Merger with a Total Mass of 150 M⊙
2020
LIGO Scientific Collaboration and Virgo Collaboration: et al.
An Indication of Anisotropy in Arrival Directions of Ultra-high-energy Cosmic Rays through Comparison to the Flux Pattern of Extragalactic Gamma-Ray …
2018
A new analysis of the dataset from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above 20 EeV with zenith angles up to 80 deg recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS …
Filter approach to the stochastic analysis of MDOF wind-excited structures
1999
Abstract In this paper, an approach useful for stochastic analysis of the Gaussian and non-Gaussian behavior of the response of multi-degree-of-freedom (MDOF) wind-excited structures is presented. This approach is based on a particular model of the multivariate stochastic wind field based upon a particular diagonalization of the power spectral density (PSD) matrix of the fluctuating part of wind velocity. This diagonalization is performed in the space of eigenvectors and eigenvalues that are called here wind-eigenvalues and wind-eigenvectors, respectively. From the examination of these quantities it can be recognized that the wind-eigenvectors change slowly with frequency while the first wi…
Multiplicity results for systems of asymptotically linear second order equations
2002
Abstract We prove the existence and multiplicity of solutions, with prescribed nodal properties, for a BVP associated with a system of asymptotically linear second order equations. The applicability of an abstract continuation theorem is ensured by upper and lower bounds on the number of zeros of each component of a solution.
Carotid plaque detection improves the predictve value of CHA2DS2-VASc score in patients with non-valvular atrial fibrilation: The ARAPACIS Study
2017
Abstract Background and aims Vascular disease (VD), as assessed by history of myocardial infarction or peripheral artery disease or aortic plaque, increases stroke risk in atrial fibrillation (AF), and is a component of risk assessment using the CHA 2 DS 2 -VASc score. We investigated if systemic atherosclerosis as detected by ultrasound carotid plaque (CP) could improve the predictive value of the CHA 2 DS 2 -VASc score. Methods We analysed data from the ARAPACIS study, an observational study including 2027 Italian patients with non-valvular AF, in whom CP was detected using Doppler Ultrasonography. Results VD was reported in 351 (17.3%) patients while CP was detected in 16.6% patients. Ad…
Coastal zone water quality: Calibration of a water-turbidity equation for MODIS data
2013
AbstractA nephelometric turbidity algorithm has been specifically calibrated for coastal waters in Sicily. To this purpose, intensive field campaigns were performed in July, August and September 2008. Measurements were collected in situ in three different gulfs. Statistical analysis suggests that field data should be spatially grouped but temporally separated; hence, new calibration parameters have been proposed.Turbidity retrieved by applying the algorithm using literature coefficients and the ones calibrated in situ are shown and compared. The comparison demonstrated that a specific calibration was necessary for quantitatively monitoring turbidity in Sicilian gulfs.
Utility of Hovmöller diagrams to diagnose Rossby wave trains
2011
The study investigates and compares various methods that aim to diagnose Rossby wave trains with the help of Hovm¨ oller diagrams. Three groups of methods are distinguished: The first group contains trough-and-ridge Hovm¨ oller diagrams of the meridional wind; they provide full phase information, but differ in the method for latitudinal averaging or weighting. The second group aims to identify Rossby wave trains as a whole, discounting individual troughs and ridges. The third group contains diagnostics which focus on physical mechanisms during the different phases of a Rossby wave train life cycle; they include the analysis of eddy kinetic energy and methods for quantifying Rossby wave brea…
The Effect of Turbulence on the Accretional Growth of Graupel
2019
Abstract Wind tunnel experiments were carried out to investigate the influence of turbulence on the collection kernel of graupel. The collection kernel defines the growth rate of a graupel accreting supercooled droplets as it falls through a cloud. The ambient conditions were similar to those occurring typically in the mixed-phase zone of convective clouds, that is, at temperatures between −7° and −16°C and with liquid water contents from 0.5 to 1.3 g m−3. Tethered spherical collectors with radii between 220 and 340 μm were exposed in a flow carrying supercooled droplets with a mean volume radius of 10 μm. The vertical root-mean-square fluctuation velocity, the dissipation rate, and the Tay…
Approaches to relativistic positioning around Earth and error estimations
2016
In the context of relativistic positioning, the coordinates of a given user may be calculated by using suitable information broadcast by a 4-tuple of satellites. Our 4-tuples belong to the Galileo constellation. Recently, we estimated the positioning errors due to uncertainties in the satellite world lines (U-errors). A distribution of U-errors was obtained, at various times, in a set of points covering a large region surrounding Earth. Here, the positioning errors associated to the simplifying assumption that photons move in Minkowski space-time (S-errors) are estimated and compared with the U-errors. Both errors have been calculated for the same points and times to make comparisons possib…
2018
Abstract. Air traffic affects cloudiness, and thus climate, by emitting exhaust gases and particles. The study of the evolution of contrail properties is very challenging due to the complex interplay of vortex dynamics and the atmospheric environment (e.g. temperature, supersaturation). Despite substantial progress in recent years, the optical, microphysical, and macrophysical properties of contrails and ambient cirrus during contrail formation and subsequent ageing are still subject to large uncertainties due to instrumental and observational limitations and the large number of variables influencing the contrail life cycle. In this study, various contrail cases corresponding to different a…