637 research outputs found
Green and Producer Lobbies: Enemies or Allies?.
In this paper we employ a common agency model to study the role of green and producer lobbies in the determination of trade and environmental policies. We focus on two large countries that are linked by trade flows and transboundary pollution externalities. We show that the nature of the relationship between lobbies and the relative efficiency of unilateral and cooperative policy outcomes depend crucially on three factors: the type of policy regime, whether governments act unilaterally or cooperatively, and the extend of the 'pollution leakages'.POLLUTION ; INTERNATIONAL TRADE ; ENVIRONMENTAL POLICY
Issue Linkage and Issue Tie-in in Multilateral Negotiations.
We describe a model of international, multidimensional policy coordination where countries can enter into selective and separate agreements with different partners along different policy dimensions. The model is used to examine the implications of negotiation tie-in - the requirement that agreements must span multiple dimensions of interaction - for the viability of multilateral cooperation when countries are linked by international trade flows and transboundary pollution.TRADE ; ENVIRONMENTAL POLICY ; NEGOCIATIONS
Analytical computation of the off-axis Effective Area of grazing incidence X-ray mirrors
Focusing mirrors for X-ray telescopes in grazing incidence, introduced in the
70s, are characterized in terms of their performance by their imaging quality
and effective area, which in turn determines their sensitivity. Even though the
on-axis effective area is assumed in general to characterize the collecting
power of an X-ray optic, the telescope capability of imaging extended X-ray
sources is also determined by the variation in its effective area with the
off-axis angle. [...] The complex task of designing optics for future X-ray
telescopes entails detailed computations of both imaging quality and effective
area on- and off-axis. Because of their apparent complexity, both aspects have
been, so far, treated by using ray-tracing routines aimed at simulating the
interaction of X-ray photons with the reflecting surfaces of a given focusing
system. Although this approach has been widely exploited and proven to be
effective, it would also be attractive to regard the same problem from an
analytical viewpoint, to assess an optical design of an X-ray optical module
with a simpler calculation than a ray-tracing routine. [...] We have developed
useful analytical formulae for the off-axis effective area of a
double-reflection mirror in the double cone approximation, requiring only an
integration and the standard routines to calculate the X-ray coating
reflectivity for a given incidence angle. [...] Algebraic expressions are
provided for the mirror geometric area, as a function of the off-axis angle.
Finally, the results of the analytical computations presented here are
validated by comparison with the corresponding predictions of a ray-tracing
code.Comment: 12 pages, 11 figures, accepted for publication in "Astronomy &
Astrophysics", section "Instruments, observational techniques, and data
processing". Updated version after grammatical revision and typos correctio
Halpha rotation curves: the soft core question
We present high resolution Halpha rotation curves of 4 late-type dwarf
galaxies and 2 low surface brightness galaxies (LSB) for which accurate HI
rotation curves are available from the literature. Observations are carried out
at Telescopio Nazionale Galileo (TNG). For LSB F583-1 an innovative dispersing
element was used, the Volume Phase Holographic (VPH) with a dispersion of about
0.35 A/pxl. We find good agreement between the Halpha data and the HI
observations and conclude that the HI data for these galaxies suffer very
little from beam smearing. We show that the optical rotation curves of these
dark matter dominated galaxies are best fitted by the Burkert profile. In the
centers of galaxies, where the N-body simulations predict cuspy cores and fast
rising rotation curves, our data seem to be in better agreement with the
presence of soft cores.Comment: Accepted for Publication in ApJ with minor changes require
Trade protection along supply chains
During the last decades, the United States has applied increasingly high trade protection against China. We combine detailed information on US antidumping (AD) duties— the most widely used trade barrier — with US input-output data to study the effects of trade protection along supply chains. To deal with endogeneity concerns, we propose a new instrument for AD protection, which combines exogenous variation in the political importance of industries with their historical experience in AD proceedings. We find that tariffs have large negative effects on downstream industries, decreasing employment, wages, sales, and investment. Our baseline estimates for 1988-2016 indicate that, due to AD protection against China, around 1.8 million US jobs were lost in downstream industries, with no significant job gains in protected sectors. When we extend the analysis to measures introduced under President Trump, we find that around 500,000 jobs were lost during the first two years of his term. We also provide evidence of the mechanisms behind the negative effects of protection along supply chains: AD duties decrease imports and raise production costs for downstream industries
Simulating the WFXT sky
We investigate the scientific impact of the Wide Field X-ray Telescope
mission. We present simulated images and spectra of X-ray sources as observed
from the three surveys planned for the nominal 5-year WFXT lifetime. The goal
of these simulations is to provide WFXT images of the extragalactic sky in
different energy bands based on accurate description of AGN populations, normal
and star forming galaxies, groups and clusters of galaxies. The images are
realized using a detailed PSF model, instrumental and physical
backgrounds/foregrounds, accurate model of the effective area and the related
vignetting effect. Thanks to this comprehensive modelization of the WFXT
properties, the simulated images can be used to evaluate the flux limits for
detection of point and extended sources, the effect of source confusion at very
faint fluxes, and in general the efficiency of detection algorithms. We also
simulate the spectra of the detected sources, in order to address specific
science topics which are unique to WFXT. Among them, we focus on the
characterization of the Intra Cluster Medium (ICM) of high-z clusters, and in
particular on the measurement of the redshift from the ICM spectrum in order to
build a cosmological sample of galaxy clusters. The end-to-end simulation
procedure presented here, is a valuable tool in optimizing the mission design.
Therefore, these simulations can be used to reliably characterize the WFXT
discovery space and to verify the connection between mission requirements and
scientific goals. Thanks to this effort, we can conclude on firm basis that an
X-ray mission optimized for surveys like WFXT is necessary to bring X-ray
astronomy at the level of the optical, IR, submm and radio wavebands as
foreseen in the coming decade.Comment: "Proceedings of "The Wide Field X-ray Telescope Workshop", held in
Bologna, Italy, Nov. 25-26 2009. To appear in Memorie della Societa
Astronomica Italiana 2010 (arXiv:1010.5889)
Trade protection along supply chains: how antidumping measures against China hurt downstream industries
Production processes are often no longer confined to a single country; supply chains can be fragmented across great distances. By contrast, tariffs are often used by individual countries to protect certain industries. In new research, which studies the effects of US antidumping duties applied against China, Chad P. Bown, Paola Conconi, Aksel Erbahar and Lorenzo Trimarchi find that these protectionist [...
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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