Search results for "Lile"
showing 10 items of 78 documents
SAPERE ECONOMICO E METODO SCIENTIFICO NELL’ILLUMINISMO LOMBARDO: NOTE DA “IL CAFFÈ”
2011
Economic knowledge and scientific method in the lombard enlightenment. Notes from «Il caffè». The connections, emerging between the 16th and the 18th century, between the evolution of economic knowledge and the rise of the scientific method, are important research topics for historians of economic ideas. However, further research on the application of the scientific method is still needed, especially when we come to the analysis of how economic principles took shape in Lombardy during the Enlightenment. The same need for further research concerns the debates on economic policy during the Age of Reforms in the latter half of the eighteenth century. This is even more necessary for Milanese En…
Galilean Superconformal Symmetries
2009
We consider the non-relativistic c -> \infty contraction limit of the (N=2k)- extended D=4 superconformal algebra su(2,2;N), introducing in this way the non-relativistic (N=2k)-extended Galilean superconformal algebra. Such a Galilean superconformal algebra has the same number of generators as su(2,2|2k). The usp(2k) algebra describes the non-relativistic internal symmetries, and the generators from the coset u(2k)/usp(2k) become central charges after contraction.
Relativistic positioning: four-dimensional numerical approach in Minkowski space-time
2011
We simulate the satellite constellations of two Global Navigation Satellite Systems: Galileo (EU) and GPS (USA). Satellite motions are described in the Schwarzschild space-time produced by an idealized spherically symmetric non rotating Earth. The trajectories are then circumferences centered at the same point as Earth. Photon motions are described in Minkowski space-time, where there is a well known relation, Coll, Ferrando & Morales-Lladosa (2010), between the emission and inertial coordinates of any event. Here, this relation is implemented in a numerical code, which is tested and applied. The first application is a detailed numerical four-dimensional analysis of the so-called emissi…
Relativistic positioning: errors due to uncertainties in the satellite world lines
2014
Global navigation satellite systems use appropriate satellite constellations to get the coordinates of an user -close to Earth- in an almost inertial reference system. We have simulated both GPS and GALILEO constellations. Uncertainties in the satellite world lines lead to dominant positioning errors. In this paper, a detailed analysis of these errors is developed inside a great region surrounding Earth. This analysis is performed in the framework of the so-called relativistic positioning systems. Our study is based on the Jacobian, J, of the transformation giving the emission coordinates in terms of the inertial ones. Around points of vanishing J, positioning errors are too large. We show …
Sachs-Wolfe at second order: the CMB bispectrum on large angular scales
2009
We calculate the Cosmic Microwave Background anisotropy bispectrum on large angular scales in the absence of primordial non-Gaussianities, assuming exact matter dominance and extending at second order the classic Sachs-Wolfe result delta T/T = Phi/3. The calculation is done in Poisson gauge. Besides intrinsic contributions calculated at last scattering, one must consider integrated effects. These are associated to lensing, and to the time dependence of the potentials (Rees-Sciama) and of the vector and tensor components of the metric generated at second order. The bispectrum is explicitly computed in the flat-sky approximation. It scales as l(-4) in the scale invariant limit and the shape d…
Effective Boost and 'Point Form' Approach
2002
Triangle Feynman diagrams can be considered as describing form factors of states bound by a zero-range interaction. These form factors are calculated for scalar particles and compared to point-form and non-relativistic results. By examining the expressions of the complete calculation in different frames, we obtain an effective boost transformation which can be compared to the relativistic kinematical one underlying the present point-form calculations, as well as to the Galilean boost. The analytic expressions obtained in this simple model allow a qualitative check of certain results obtained in similar studies. In particular, a mismatch is pointed out between recent practical applications o…
The GALILEO γ-ray array at the Legnaro National Laboratories
2021
Abstract GALILEO, a new 4 π high-resolution γ -detection array, based on HPGe detectors, has been developed and installed at the Legnaro National Laboratories. The GALILEO array greatly benefits from a fully-digital read-out chain, customized DAQ, and a variety of complementary detectors to improve the resolving power by the detection of particles, ions or high-energy γ -ray transitions. In this work, a full description of the array, including electronics and DAQ, is presented together with its complementary instrumentation.
Comparison of different boost transformations for the calculation of form factors in relativistic quantum mechanics
2002
The effect of different boost expressions, pertinent to the instant, front and point forms of relativistic quantum mechanics, is considered for the calculation of the ground-state form factor of a two-body system in simple scalar models. Results with a Galilean boost as well as an explicitly covariant calculation based on the Bethe-Salpeter approach are given for comparison. It is found that the present so-called point-form calculations of form factors strongly deviate from all the other ones. This suggests that the formalism which underlies them requires further elaboration. A proposition in this sense is made.
Zvaigžņotā Debess: 2009, Pavasaris (203)
2009
Contents: E.R.Mustel, President of the Astronomical Council of the USSR Academy of Sciences. Congratulations to Editorial Board of “Zvaigžņotā debess” ; Z.Alksne. Gould’s Belt ; I.Daube. At the Radioastrophysical Observatory of the Latvian Academy of Sciences ; Z.Alksne, A.Alksnis. Lopsided Galaxies ; A.Alksnis. HII Region Gum 29 – a Stellar Nursery ; D.Docenko. On Collision of Asteroid 2008 TC3 with the Earth ; V.Lapoška. On „Leap Second” ; I.Vilks, M.Gills. Beginning of the International Year of Astronomy in Paris: Impressions by Latvian Delegates ; J.Jaunbergs. Equatorial Ridge on Iapetus ; M.Sudārs. Space Shuttle Is Not Likely to Retire Next Year ; I.Vilks. Planet Satellite Names in Lat…
Posidonia oceanica as a Historical Monitor Device of Lead Concentration in Marine Environment
2005
We show that Posidonia oceanica is able to reliably monitor the variability of environmental lead (Pb). We analyze lead concentration measured in the scales and rhizomes of Posidonia oceanica collected in seven sites along the coasts of the Sicily island and subsequently fractioned them according to a lepidochronological analysis. We measure lead concentration in Posidonia oceanica tissues by using the flame atomic absorption spectrophotometry technique. We compare the measured lead concentration with the estimated lead emission in air due to the gasoline sold and used for combustion in car engines in Sicily. By computation of the Pearson cross-correlation coefficient, we show that lead con…