17,503 research outputs found
The Chinese in Southern Europe: Has urban regeneration addressed their new form of clustering?
This paper attempts to analyse the particular features of Chinese clustering in two southern European cities and the urban regeneration responses employed in the decade 2005-2015: Prato in Italy and Santa Coloma de Gramenet in Spain, which are among the cities with the highest rate of Chinese in-migration within their respective countries. The main aim is to show which urban regeneration policies have been adopted in both contexts and to evaluate, in comparative terms, how they have addressed the two local Chinese communities.
The paper will argue that their form of clustering, developed since the 1990s, has featured a certain degree of social segregation and tensions with local communities. On the other hand, they have become two dynamic urban nodes in supra-local business networks,possibly demanding new forms of engagement in the governance system. The results show that the urban regeneration policies in place have partially failed to acknowledge the changing nature of their form of clustering, with the risk to exacerbate existing conflicts and to prevent beneficial mutual collaborations
Classical resolution of singularities in dilaton cosmologies
For models of dilaton-gravity with a possible exponential potential, such as
the tensor-scalar sector of IIA supergravity, we show how cosmological
solutions correspond to trajectories in a 2D Milne space (parametrized by the
dilaton and the scale factor). Cosmological singularities correspond to points
at which a trajectory meets the Milne horizon, but the trajectories can be
smoothly continued through the horizon to an instanton solution of the
Euclidean theory. We find some exact cosmology/instanton solutions that lift to
black holes in one higher dimension. For one such solution, the singularities
of a big crunch to big bang transition mediated by an instanton phase lift to
the black hole and cosmological horizons of de Sitter Schwarzschild spacetimes.Comment: 24 pages, 2 figure
Mandatory vaccinations in European countries, undocumented information, false news and the impact on vaccination uptake: the position of the Italian pediatric society.
BACKGROUND: High rates of vaccination coverage are important in preventing infectious diseases. Enforcing mandatory vaccinations is one of the strategies that some Countries adopted to protect the community when vaccination coverage is not satisfactory. In Italy, in 2017 vaccination against diphtheria, tetanus, pertussis, hepatitis B, poliovirus, Haemophilus influenzae type b, measles, mumps, rubella and varicella became compulsory in childhood. In order to contrast vaccination policies, anti-vaccination campaigns contribute to the spread of fake news. Among them, there is the false information that Italy is the only one country with mandatory vaccination policy. Aim of our study is confronting vaccination policies in children under 18 months against among different European countries for the following vaccines: diphtheria, tetanus, pertussis, hepatitis B, poliovirus, Haemophilus influenzae type b, measles, mumps, rubella and varicella. METHODS: Information on policies of mandatory or recommended vaccinations of the European Countries were gathered by ECDC and compared to the Italian one. RESULTS: European Countries recommend or contemplate compulsory vaccines. Among them, eleven Countries (35.4%) have mandatory vaccinations for at least one out of diphtheria, tetanus, pertussis, hepatitis B, poliovirus, Haemophilus influenzae type b, measles, mumps, rubella and varicella vaccine. CONCLUSION: Not only in Italy, vaccination against diphtheria, tetanus, pertussis, hepatitis B, poliovirus, Haemophilus influenzae type b, measles, mumps, rubella and varicella is mandatory in children under 18 months. Other European countries adopted compulsory policies in order to prevent the spread of infectious diseases and to protect the community
Cosmological D-instantons and Cyclic Universes
For models of gravity coupled to hyperbolic sigma models, such as the
metric-scalar sector of IIB supergravity, we show how smooth trajectories in
the `augmented target space' connect FLRW cosmologies to non-extremal
D-instantons through a cosmological singularity. In particular, we find closed
cyclic universes that undergo an endless sequence of big-bang to big-crunch
cycles separated by instanton `phases'. We also find `big-bounce' universes in
which a collapsing closed universe bounces off its cosmological singularity to
become an open expanding universe.Comment: 21 pages, 4 figures. v2: minor change
Densificare le aree metropolitane? Le frange urbane come città potenziali.Infrastrutture tra densità e dispersione nel sistema territoriale tra Nola e Napoli
Models of Holographic superconductivity
We construct general models for holographic superconductivity parametrized by
three couplings which are functions of a real scalar field and show that under
general assumptions they describe superconducting phase transitions. While some
features are universal and model independent, important aspects of the quantum
critical behavior strongly depend on the choice of couplings, such as the order
of the phase transition and critical exponents of second-order phase
transitions. In particular, we study a one-parameter model where the phase
transition changes from second to first order above some critical value of the
parameter and a model with tunable critical exponents.Comment: 15 pages, 6 figure
Thermomechanical properties of amorphous metallic tungsten-oxygen and tungsten-oxide coatings
In this work, we investigate the correlation between morphology, composition,
and the mechanical properties of metallic amorphous tungsten-oxygen and
amorphous tungsten-oxide films deposited by Pulsed Laser Deposition. This
correlation is investigated by the combined use of Brillouin Spectroscopy and
the substrate curvature method. The stiffness of the films is strongly affected
by both the oxygen content and the mass density. The elastic moduli show a
decreasing trend as the mass density decreases and the oxygen-tungsten ratio
increases. A plateaux region is detected in correspondence of the transition
between metallic and oxide films. The compressive residual stresses, moderate
stiffness and high local ductility that characterize compact amorphous
tungsten-oxide films make them promising for applications involving thermal or
mechanical loads. The coefficient of thermal expansion is quite high (i.e. 8.9
10 K), being strictly correlated to the amorphous
structure and stoichiometry of the films. Under thermal treatments they show a
quite low relaxation temperature (i.e. 450 K). They crystallize into the
monoclinic phase of WO starting from 670 K, inducing an increase
by about 70\% of material stiffness.Comment: The research leading to these results has also received funding from
the European Research Council Consolidator Grant ENSURE (ERC-2014-CoG No.
647554). The views and opinions expressed herein do not necessarily reflect
those of the European Commissio
First optical validation of a Schwarzschild Couder telescope: the ASTRI SST-2M Cherenkov telescope
The Cherenkov Telescope Array (CTA) represents the most advanced facility
designed for Cherenkov Astronomy. ASTRI SST-2M has been developed as a
demonstrator for the Small Size Telescope in the context of the upcoming CTA.
Its main innovation consists in the optical layout which implements the
Schwarzschild-Couder configuration and is fully validated for the first time.
The ASTRI SST-2M optical system represents the first qualified example for two
mirrors telescope for Cherenkov Astronomy.
This configuration permits to (i) maintain a high optical quality across a
large FoV (ii) de-magnify the plate scale, (iii) exploit new technological
solutions for focal plane sensors. The goal of the paper is to present the
optical qualification of the ASTRI SST-2M telescope. The qualification has been
obtained measuring the PSF sizes generated in the focal plane at various
distance from the optical axis. These values have been compared with the
performances expected by design.
After an introduction on the Gamma Astronomy from the ground, the optical
design and how it has been implemented for ASTRI SST-2M is discussed. Moreover
the description of the setup used to qualify the telescope over the full field
of view is shown.
We report the results of the first--light optical qualification. The required
specification of a flat PSF of arcmin in a large field of view ~10
deg has been demonstrated. These results validate the design specifications,
opening a new scenario for Cherenkov Gamma ray Astronomy and, in particular,
for the detection of high energy (5 - 300 TeV) gamma rays and wide-field
observations with CTA.Comment: 6 pages, 5 figure
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