Roma Tre University

About: Roma Tre University is a education organization based out in Rome, Lazio, Italy. It is known for research contribution in the topics: Large Hadron Collider & Galaxy. The organization has 4434 authors who have published 15352 publications receiving 374888 citations. The organization is also known as: Universita degli Studi Roma Tre & RomaTre.

Power relationships along the value chain: multinational firms, global buyers and performance of local suppliers

Abstract: There is a growing literature exploring the role of international trade channels on economic growth, looking at the mechanisms through which import and export flows might affect productivity, technology diffusion and output growth. However, most of this literature appears to neglect an important part of the story, which is the form and the organisation of the relationships (the governance) among the various actors involved in these activities and their implications for development. The recent literature on global value chains and their governance takes this element explicitly into account, and we explore it empirically with a new dataset on Thailand. To this aim, we study global and domestic value chains in Thailand, and develop a quantitative measure of their governance, which takes into account different levels and types of buyer involvement with supplier activities. We then use this measure to explore econometrically its relationship with performance of suppliers. An important finding is that in value chains led by a multinational corporation, the relationships that the leaders have with their suppliers is multifold and generally more intense than for domestic value chains. Our estimates suggest that more intense buyer involvement with local suppliers, not only in the definition of product characteristics, design and quality, but also in technology dissemination and R&D, is generally associated with higher supplier productivity. This is consistent with other sources of evidence. However, the governance of the value chain appears to affect the productivity of suppliers in domestic value chains to a greater extent than for firms supplying multinational corporations or for exporters. We suggest that this result may be explained by the different nature of the information and knowledge being exchanged, and by the larger gaps in knowledge and capabilities between the domestic leader and its suppliers.

Kaon mixing beyond the SM from Nf = 2 tmQCD and model independent constraints from the UTA

Abstract: We present the first unquenched, continuum limit, lattice QCD results for the matrix elements of the operators describing neutral kaon oscillations in extensions of the Standard Model. Owing to the accuracy of our calculation on ∆S = 2 weak Hamiltonian matrix elements, we are able to provide a refined Unitarity Triangle analysis improving the bounds coming from model independent constraints on New Physics. In our nonperturbative computation we use a combination of N f = 2 maximally twisted sea quarks and Osterwalder-Seiler valence quarks in order to achieve both O(a)-improvement and continuum-like renormalization properties for the relevant four-fermion operators. The calculation of the renormalization constants has been performed non-perturbatively in the RI-MOM scheme. Based on simulations at four values of the lattice spacing and a number of quark masses we have extrapolated/interpolated our results to the continuum limit and physical light/strange quark masses.

Continuum modelling of pantographic sheets for out-of-plane bifurcation and vibrational analysis

Abstract: A nonlinear two-dimensional (2D) continuum with a latent internal structure is introduced as a coarse model of a plane network of beams which, in turn, is assumed as a model of a pantographic structure made up by two families of equispaced beams, superimposed and connected by pivots. The deformation measures of the beams of the network and that of the 2D body are introduced and the former are expressed in terms of the latter by making some kinematical assumptions. The expressions for the strain and kinetic energy densities of the network are then introduced and given in terms of the kinematic quantities of the 2D continuum. To account for the modelling abilities of the 2D continuum in the linear range, the eigenmode and eigenfrequencies of a given specimen are determined. The buckling and post-buckling behaviour of the same specimen, subjected to two different loading conditions are analysed as tests in the nonlinear range. The problems have been solved numerically by means of the COMSOL Multiphysics finite element software.

Coherent-mode decomposition of partially polarized, partially coherent sources.

Abstract: It is shown that any partially polarized, partially coherent source can be expressed in terms of a suitable superposition of transverse coherent modes with orthogonal polarization states. Such modes are determined through the solution of a system of two coupled integral equations. An example, for which the modal decomposition is obtained in closed form in terms of fully linearly polarized Hermite Gaussian modes, is given.

The HELLAS2XMM survey - VI. X-ray absorption in the 1df AGN sample through a spectral analysis

Abstract: The spectroscopic analysis of 117 serendipitous sources in the HELLAS2XMM 1df (1 degree field) survey is de- scribed. Of these, 106 sources, of which 86% have a spectroscopic redshift, are used to evaluate the fraction of X-ray absorbed (log NH > 22) Active Galactic Nuclei (AGN) in the 2−10 keV flux range 0.8−20 × 10 −14 erg cm −2 s −1 . This fraction turns out lower than what is predicted by two well known Cosmic X-Ray Background synthesis models, and the discrepancy is signifi- cant at the 99.999% level. This result consolidates the findings recently obtained by other authors. In the flux interval explored, the data are consistent with an intrinsic distribution of the absorbing columns (flat per decade above log NH > 21) independent of luminosity and redshift, together with an AGN luminosity function evolving purely in luminosity. It is shown that, on the other hand, extrapolation to lower fluxes fails to reproduce the results inferred from the Chandra Deep Field North survey. It is found that about 40% of the high luminosity sources in our sample have best fit log NH > 22, and the surface density of these X-ray obscured QSOs can then be estimated at about 48 per square degree, at the flux limit of ∼10 −14 erg cm −2 s −1 of the HELLAS2XMM 1df survey. As a side issue, 5 or 6 out of 60 sources, that is about 10%, identified with broad line AGN, turn out to be affected by log NH > 22 absorption.