3,127 research outputs found
Recommended from our members
Trade Adjustment Assistance (TAA) and Its Role in U.S. Trade Policy
[Excerpt] When Congress passed the Reciprocal Trade Agreements Act (RTAA) of 1934, it reflected an important transition in ânational trade policyâ away from âprotectionismâ toward greater âtrade liberalization.â This shift continues to be the dominant, but hardly uncontested, trade policy of the United States. The substantial national gains from trade have long been recognized, yet trade liberalizing legislation often faces strong political opposition because related costs, although much smaller, affect a vocal and concentrated constituency. Congress first addressed this inherent tension with legislation that allowed for the reimposition of tariffs and other trade barriers when domestic industries were threatened or hurt by imports. In 1962, however, Congress adopted an additional approach by providing trade adjustment assistance (TAA) directly to trade-affected firms and workers. It remains a controversial pillar of U.S. trade policy today.
This report discusses the role of TAA in U.S. trade policy, from its inception as a legislative option in the early 1950s, to its core role as an alternative to import relief that many argue has served to promote the long-term U.S. trade liberalization agenda. It will also consider the extent to which TAA has been linked to both renewal of trade agreements authority, and passage of trade agreement implementing legislation. TAA has become an integral part of an increasingly complex U.S. trade policy. Understanding the origins of TAA, the historical congressional debate, and legislative options considered by Congress over the past 50 years may help inform the current discussion of TAA reauthorization
Lattice constraints on the thermal photon rate
We estimate the photon production rate from an SU(3) plasma at temperatures
of about 1.1Tc and 1.3Tc. Lattice results for the vector current correlator at
spatial momenta k ~ (2-6)T are extrapolated to the continuum limit and analyzed
with the help of a polynomial interpolation for the corresponding spectral
function, which vanishes at zero frequency and matches to high-precision
perturbative results at large invariant masses. For small invariant masses the
interpolation is compared with the NLO weak-coupling result, hydrodynamics, and
a holographic model. At vanishing invariant mass we extract the photon rate
which for k \gsim 3T is found to be close to the NLO weak-coupling prediction.
For k \lsim 2T uncertainties remain large but the photon rate is likely to fall
below the NLO prediction, in accordance with the onset of a strongly
interacting behaviour characteristic of the hydrodynamic regime.Comment: 20 pages. v2: clarifications adde
Four-loop lattice-regularized vacuum energy density of the three-dimensional SU(3) + adjoint Higgs theory
The pressure of QCD admits at high temperatures a factorization into purely
perturbative contributions from "hard" thermal momenta, and slowly convergent
as well as non-perturbative contributions from "soft" thermal momenta. The
latter can be related to various effective gluon condensates in a dimensionally
reduced effective field theory, and measured there through lattice simulations.
Practical measurements of one of the relevant condensates have suffered,
however, from difficulties in extrapolating convincingly to the continuum
limit. In order to gain insight on this problem, we employ Numerical Stochastic
Perturbation Theory to estimate the problematic condensate up to 4-loop order
in lattice perturbation theory. Our results seem to confirm the presence of
"large" discretization effects, going like , where is the
lattice spacing. For definite conclusions, however, it would be helpful to
repeat the corresponding part of our study with standard lattice perturbation
theory techniques.Comment: 35 pages. v2: minor corrections, published versio
Heavy quark medium polarization at next-to-leading order
We compute the imaginary part of the heavy quark contribution to the photon
polarization tensor, i.e. the quarkonium spectral function in the vector
channel, at next-to-leading order in thermal QCD. Matching our result, which is
valid sufficiently far away from the two-quark threshold, with a previously
determined resummed expression, which is valid close to the threshold, we
obtain a phenomenological estimate for the spectral function valid for all
non-zero energies. In particular, the new expression allows to fix the overall
normalization of the previous resummed one. Our result may be helpful for
lattice reconstructions of the spectral function (near the continuum limit),
which necessitate its high energy behaviour as input, and can in principle also
be compared with the dilepton production rate measured in heavy ion collision
experiments. In an appendix analogous results are given for the scalar channel.Comment: 43 pages. v2: a figure and other clarifications added, published
versio
Recommended from our members
In the Spotlight: Biomedical Imaging
This article reviews some of the more recent advances and trends in the area of biomedical imaging. Real-time multimodality imaging and image-guided interventions are presented as well as other fast growing areas of interdisciplinary research and development. Segmentation, registration and spatial-temporal integration in medical image processing are also discussed
Where does the hot electroweak phase transition end?
We give the nonperturbative phase diagram of the four-dimensional hot
electroweak phase transition. A systematic extrapolation is done. Our
results show that the finite temperature SU(2)-Higgs phase transition is of
first order for Higgs-boson masses GeV. The full
four-dimensional result agrees completely with that of the dimensional
reduction approximation. This fact is of particular importance, because it
indicates that the fermionic sector of the Standard Model (SM) can be included
perturbatively. We obtain that the Higgs-boson endpoint mass in the SM is GeV. Taking into account the LEP Higgs-boson mass lower bound excludes
any electroweak phase transition in the SM.Comment: LATTICE98(electroweak), presented by Z. Fodor. Latex, 3 pages, 3 figu
res. Comment line change
The leading non-perturbative coefficient in the weak-coupling expansion of hot QCD pressure
Using Numerical Stochastic Perturbation Theory within three-dimensional pure
SU(3) gauge theory, we estimate the last unknown renormalization constant that
is needed for converting the vacuum energy density of this model from lattice
regularization to the MSbar scheme. Making use of a previous non-perturbative
lattice measurement of the plaquette expectation value in three dimensions,
this allows us to approximate the first non-perturbative coefficient that
appears in the weak-coupling expansion of hot QCD pressure.Comment: 16 pages. v2: published versio
Renormalization of infrared contributions to the QCD pressure
Thanks to dimensional reduction, the infrared contributions to the QCD
pressure can be obtained from two different three-dimensional effective field
theories, called the Electrostatic QCD (Yang-Mills plus adjoint Higgs) and the
Magnetostatic QCD (pure Yang-Mills theory). Lattice measurements have been
carried out within these theories, but a proper interpretation of the results
requires renormalization, and in some cases also improvement, i.e. the removal
of terms of O(a) or O(a^2). We discuss how these computations can be
implemented and carried out up to 4-loop level with the help of Numerical
Stochastic Perturbation Theory.Comment: 7 pages, 4 figures, talk presented at Lattice 2006 (High temperature
and density
Recommended from our members
Hexagonal QMF Banks and Wavelets
In this chapter we shall lay bare the theory and implementation details of hexagonal sampling systems and hexagonal quadrature mirror filters (HQMF). Hexagonal sampling systems are of particular interest because they exhibit the tightest packing of all regular two-dimensional sampling systems and for a circularly band-limited waveform, hexagonal sampling requires 13.4 percent fewer samples than rectangular sampling. In addition, hexagonal sampling systems also lead to nonseparable quadrature mirror filters in which all basis functions are localized in space, spatial frequency and orientation. This chapter is organized in two sections. Section I describes the theoretical aspects of hexagonal sampling systems while Section II covers important implementation details
Texture Classification by Wavelet Packet Signatures
This correspondence introduces a new approach to characterize textures at multiple scales. The performance of wavelet packet spaces are measured in terms of sensitivity and selectivity for the classification of twenty-five natural textures. Both energy and entropy metrics were computed for each wavelet packet and incorporated into distinct scale space representations, where each wavelet packet (channel) reflected a specific scale and orientation sensitivity. Wavelet packet representations for twenty-five natural textures were classified without error by a simple two-layer network classifier. An analyzing function of large regularity (D20) was shown to be slightly more efficient in representation and discrimination than a similar function with fewer vanishing moments (D6) In addition, energy representations computed from the standard wavelet decomposition alone (17 features) provided classification without error for the twenty-five textures included in our study. The reliability exhibited by texture signatures based on wavelet packets analysis suggest that the multiresolution properties of such transforms are beneficial for accomplishing segmentation, classification and subtle discrimination of texture
- âŠ