824 research outputs found
QUALITY RESTRICTIONS AS BARRIERS TO TRADE: THE CASE OF EUROPEAN COMMUNITY REGULATIONS ON THE USE OF HORMONES
Sanitary regulations, product definitions, grades, production or processing regulations, and other qualitative standards are generally applied to both domestic production and imported goods. These quality restrictions can be seen as trade barriers, although it is often difficult to determine whether a given restriction is based on legitimate health or safety concerns or is simply an alternative device for protecting producers. The purpose of this paper is to evaluate the welfare effects of a recent quality regulation, the European Community ban on the use of hormones in livestock production. A conceptual framework is developed to analyze the effects of the ban on the market for edible offals. The results indicate that Community prices for edible offals will increase 34% to 45%, while the world price will fall by at least 35%.Food Consumption/Nutrition/Food Safety, International Relations/Trade,
Unidentifed gamma-ray sources: hunting gamma-ray blazars
One of the main scientific objectives of the ongoing Fermi mission is
unveiling the nature of the unidentified gamma-ray sources (UGSs). Despite the
large improvements of Fermi in the localization of gamma-ray sources with
respect to the past gamma-ray missions, about one third of the Fermi-detected
objects are still not associated to low energy counterparts. Recently, using
the Wide-Field Infrared Survey Explorer (WISE) survey, we discovered that
blazars, the rarest class of Active Galactic Nuclei and the largest population
of gamma-ray sources, can be recognized and separated from other extragalactic
sources on the basis of their infrared (IR) colors. Based on this result, we
designed an association method for the gamma-ray sources to reognize if there
is a blazar candidate within the positional uncertainty region of a generic
gamma-ray source. With this new IR diagnostic tool, we searched for gamma-ray
blazar candidates associated to the UGS sample of the second Fermi gamma-ray
catalog (2FGL). We found that our method associates at least one gamma-ray
blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These
new low-energy candidates have the same IR properties as the blazars associated
to gamma-ray sources in the 2FGL catalog.Comment: 24 pages, 4 figures, Accepted for publication on the Astrophysical
Journa
Hidden AGNs in Early-Type Galaxies
We present a stacking analysis of the complete sample of Early Type Galaxies
(ETGs) in the \textit{Chandra} COSMOS (C-COSMOS) survey, to explore the nature
of the X-ray luminosity in the redshift and stellar luminosity ranges
and {10}^{9}. Using established
scaling relations, we subtract the contribution of X-ray binary populations, to
estimate the combined emission of hot ISM and AGN. To discriminate between the
relative importance of these two components, we (1) compare our results with
the relation observed in the local universe for
hot gaseous halos emission in ETGs, and (2) evaluate the spectral signature of
each stacked bin. We find two regimes where the non-stellar X-ray emission is
hard, consisten t with AGN emission. First, there is evidence of hard, absorbed
X-ray emission in stacked bins including relatively high z () ETGs
with average high X-ray luminosity (L_{X-LMXB}\gtrsim 6\times{10}^{42}\mbox{
erg}/\mbox{s}). These luminosities are consistent with the presence ofhighly
absorbed "hidden" AGNs in these ETGs, which are not visible in their optical-IR
spectra and spectral energy distributions. Second, confirming the early
indication from our C-COSMOS study of X-ray detected ETGs, we find
significantly enhanced X-ray luminoaity in lower stellar mass ETGs
(L_K\lesssim{10}^{11}L_{\astrosun}), relative to the local
relation. The stacked spectra of these ETGs also
suggest X-ray emission harder than expected from gaseous hot halos. This
emission is consistent with inefficient accretion
onto M_{BH}\sim
{10}^{6}-{10}^{8}\,M_{\astrosun}.Comment: 22 pages, 7 figures, 2 tables. Accepted for publications on Ap
A Chandra Snapshot Survey for 3C Radio Galaxies with redshifts between 0.3 and 0.5
This paper contains an analysis of short Chandra observations of 19 3C
sources with redshifts between 0.3 and 0.5 not previously observed in the
X-rays. This sample is part of a project to obtain Chandra data for all of the
extragalactic sources in the 3C catalogue. Nuclear X-ray intensities as well as
any X-ray emission associated with radio jet knots, hotspots or lobes have been
measured in 3 energy bands: soft, medium and hard. Standard X-ray spectral
analysis for the 4 brightest nuclei has been also performed. X-ray emission was
detected for all the nuclei of the radio sources in the current sample with the
exception of 3C 435A. There is one compact steep spectrum (CSS) source while
all the others are FRII radio galaxies. X-ray emission from two galaxy clusters
(3C 19 and 3C 320); from 6 hotspots in 4 radio galaxies (3C 16, 3C 19, 3C
268.2, 3C 313); and extended X-ray emission on kpc scales in 3C 187 and 3C 313,
has been detected.Comment: 33 pages, 22 figures, 7 tables, accepted for publication on the ApJ
Supplement Series. arXiv admin note: text overlap with arXiv:1210.602
Early-type galaxies in the Chandra COSMOS Survey
We study a sample of 69 X-ray detected Early Type Galaxies (ETGs), selected
from the Chandra COSMOS survey, to explore the relation between the X-ray
luminosity of hot gaseous halos (L_X, gas) and the integrated stellar
luminosity (L_K) of the galaxies, in a range of redshift extending out to
z=1.5. In the local universe a tight steep relationship has been stablished
between these two quantities (L_X,gas~ L_K^4.5) suggesting the presence of
largely virialized halos in X-ray luminous systems. We use well established
relations from the study of local universe ETGs, together with the expected
evolution of the X-ray emission, to subtract the contribution of low mass X-ray
binary populations (LMXBs) from the X-ray luminosity of our sample. Our
selection minimizes the presence of active galactic nuclei (AGN), yielding a
sample representative of normal passive COSMOS ETGs; therefore the resulting
luminosity should be representative of gaseous halos, although we cannot
exclude other sources such as obscured AGN, or enhanced X-ray emission
connected with embedded star formation in the higher z galaxies. We find that
most of the galaxies with estimated L_X<10^42 erg/s and z<0.55 follow the
L_X,gas- L_K relation of local universe ETGs. For these galaxies, the
gravitational mass can be estimated with a certain degree of confidence from
the local virial relation. However, the more luminous (10^42<L_X<10^43.5 erg/s)
and distant galaxies present significantly larger scatter; these galaxies also
tend to have younger stellar ages. The divergence from the local L_X,gas - L_K
relation in these galaxies implies significantly enhanced X-ray emission, up to
a factor of 100 larger than predicted from the local relation. We discuss the
implications of this result for the presence of hidden AGN, and the evolution
of hot halos, in the presence of nuclear and star formation feedback.Comment: 29 pages, 10 figures, accepted for publication on ApJ on May 27 201
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