3,733 research outputs found
CONVERGENCE, HARMONIZATION, AND COMPATIBILITY UNDER NAFTA: A 2003 STATUS REPORT
In the 2001 Workshop the authors developed and applied a taxonomy and framework for assessing the status of agricultural and food policies in each of the NAFTA countries (Knutson, Loyns and Ochoa, 2002). It divided the policies into the following areas: -Facilitate growth and progress. Regulation. Market intervention. For each area the paper identified the major points of conflict that existed in 2001 at the time the paper was written and the requirements for harmonization. The major areas of conflict included; -Facilitate growth and progress: particularly grades and standards in grains (US-CA) and beef (US-CA); trade policy in dairy (US-CA), sugar (US-MX), poultry (US-MX), and wheat (US-CA); infrastructure policies (border conflicts US-MX). Regulation: particularly plant and animal protection (US-MX), food safety (US-MX), pesticides (US-CA-MX). Market interventions: particularly disaster assistance (US-CA-MX), price supports and safety nets (US-CA-MX), and supply management and state trading. The purpose of this paper is to update that paper and to draw conclusions as to whether progress has been made since 2001 has been positive, negative, or neutral in each of these areas of conflict for policy/program convergence, harmonization, and compatibility. The 2001 policies, therefore, can be looked upon as a policy baseline point of reference for comparison in 2003. Many of the policy changes were embodied in the precipitated by the US 2002 farm bill. However, care was taken to review each of the policy/program areas covered in the 2001 taxonomy to identify changes in the level of conflict.International Relations/Trade,
Asphericity and clumpiness in the winds of Luminous Blue Variables
We present the first systematic spectropolarimetric study of Luminous Blue
Variables (LBVs) in the Galaxy and the Magellanic Clouds, in order to
investigate the geometries of their winds. We find that at least half of our
sample show changes in polarization across the strong H emission line,
indicating that the light from the stars is intrinsically polarized and
therefore that asphericity already exists at the base of the wind. Multi-epoch
spectropolarimetry on four targets reveals variability in their intrinsic
polarization. Three of these, AG Car, HR Car and P Cyg, show a position angle
(PA) of polarization which appears random with time. Such behaviour can be
explained by the presence of strong wind-inhomogeneities, or `clumps' within
the wind. Only one star, R 127, shows variability at a constant PA, and hence
evidence for axi-symmetry as well as clumpiness. However, if viewed at low
inclination, and at limited temporal sampling, such a wind would produce a
seemingly random polarization of the type observed in the other three stars.
Time-resolved spectropolarimetric monitoring of LBVs is therefore required to
determine if LBV winds are axi-symmetric in general.
The high fraction of LBVs ( 50%) showing intrinsic polarization is to be
compared with the lower 20-25 % for similar studies of their
evolutionary neighbours, O supergiants and Wolf-Rayet stars. We anticipate that
this higher incidence is due to the lower effective gravities of the LBVs,
coupled with their variable temperatures within the bi-stability jump regime.
This is also consistent with the higher incidence of wind asphericity that we
find in LBVs with strong H emission and recent (last 10 years)
strong variability.Comment: 20 pages, 12 figures, accepted by A&
The Lutz-Kelker bias in trigonometric parallaxes
The theoretical prediction that trigonometric parallaxes suffer from a
statistical effect, has become topical again now that the results of the
Hipparcos satellite have become available. This statistical effect, the
so-called Lutz-Kelker bias, causes measured parallaxes to be too large. This
has the implication that inferred distances, and hence inferred luminosities
are too small. Published analytic calculations of the Lutz-Kelker bias indicate
that the inferred luminosity of an object is, on average, 30% too small when
the error in the parallax is only 17.5%. Yet, this bias has never been
determined empirically. In this paper we investigate whether there is such a
bias by comparing the best Hipparcos parallaxes which ground-based
measurements. We find that there is indeed a large bias affecting parallaxes,
with an average and scatter comparable to predictions. We propose a simple
method to correct for the LK bias, and apply it successfully to a sub-sample of
our stars. We then analyze the sample of 26 `best' Cepheids used by Feast &
Catchpole (1997) to derive the zero-point of the fundamental mode pulsators and
leads to a distance modulus to the Large Magellanic Cloud - based on Cepheid
parallaxes- of 18.56 +/- 0.08, consistent with previous estimates.Comment: MNRAS Letters in press; 6 pages LaTeX, 6 ps figure
Is there a flavor hierarchy in the deconfinement transition of QCD?
We present possible indications for flavor separation during the QCD
crossover transition based on continuum extrapolated lattice QCD calculations
of higher order susceptibilities. We base our findings on flavor specific
quantities in the light and strange quark sector. We propose a possible
experimental verification of our prediction, based on the measurement of higher
order moments of identified particle multiplicities. Since all our calculations
are performed at zero baryochemical potential, these results are of particular
relevance for the heavy ion program at the LHC.Comment: 5 pages, 3 figures, revte
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