6,790 research outputs found
Effects of Antidumping Duties with Bertrand Competition: Some Evidence for Frozen Catfish Fillets
Antidumping duties are popular in the United States because under the Byrd Amendment domestic industry gets to keep tariff revenues. However, whether antidumping duties are an effective instrument of protection depends crucially on the tariff's ability to increase demand for the home good. Under Bertrand competition, the Byrd Amendment enhances tariff effects on the home price and trade flows in comparison to perfect competition. Assuming Bertrand competition and differentiated products, price-reaction functions of frozen catfish fillets are derived and estimated jointly with a demand equation using monthly data for the period January 1999 - December 2005. An inverse demand equation for farm-level products is also added to explore the efficacy of the tariff on price of farmed catfish. The estimated increase associated with the duty is exhibited tiny in price and sales of domestic fillets but insignificant in farm price. The result suggests antidumping duties are a weak tool for protecting the domestic catfish industry.antidumping tariff, Bertrand competition, Byrd Amendment, catfish, price, International Relations/Trade, Resource /Energy Economics and Policy,
Unexpected Outcomes during the Attempted Iodination of Biphenol
The goal of this research was to create a new procedure to iodinate 4,4- biphenol using a ball miller. Iodination of 4,4-biphenol was first attempted in solution using electrophilic aromatic substitution. Several attempts were made to iodinate 4,4-biphenol, but the general insolubility of crude products inhibited progress. Interestingly, NMR analysis of the aqueous ammonia product suggested that 4,4-biphenol dimerized or polymerized with itself to make an ether. The exact mechanism by which the ether dimer was created is unknown, but the reaction may have occurred using a radical mechanism. Though the original goal of the project is left unmet, a future inquiry into the ether dimer could prove just as fascinating
A Rate-Distortion Exponent Approach to Multiple Decoding Attempts for Reed-Solomon Codes
Algorithms based on multiple decoding attempts of Reed-Solomon (RS) codes
have recently attracted new attention. Choosing decoding candidates based on
rate-distortion (R-D) theory, as proposed previously by the authors, currently
provides the best performance-versus-complexity trade-off. In this paper, an
analysis based on the rate-distortion exponent (RDE) is used to directly
minimize the exponential decay rate of the error probability. This enables
rigorous bounds on the error probability for finite-length RS codes and leads
to modest performance gains. As a byproduct, a numerical method is derived that
computes the rate-distortion exponent for independent non-identical sources.
Analytical results are given for errors/erasures decoding.Comment: accepted for presentation at 2010 IEEE International Symposium on
Information Theory (ISIT 2010), Austin TX, US
On Multiple Decoding Attempts for Reed-Solomon Codes: A Rate-Distortion Approach
One popular approach to soft-decision decoding of Reed-Solomon (RS) codes is
based on using multiple trials of a simple RS decoding algorithm in combination
with erasing or flipping a set of symbols or bits in each trial. This paper
presents a framework based on rate-distortion (RD) theory to analyze these
multiple-decoding algorithms. By defining an appropriate distortion measure
between an error pattern and an erasure pattern, the successful decoding
condition, for a single errors-and-erasures decoding trial, becomes equivalent
to distortion being less than a fixed threshold. Finding the best set of
erasure patterns also turns into a covering problem which can be solved
asymptotically by rate-distortion theory. Thus, the proposed approach can be
used to understand the asymptotic performance-versus-complexity trade-off of
multiple errors-and-erasures decoding of RS codes.
This initial result is also extended a few directions. The rate-distortion
exponent (RDE) is computed to give more precise results for moderate
blocklengths. Multiple trials of algebraic soft-decision (ASD) decoding are
analyzed using this framework. Analytical and numerical computations of the RD
and RDE functions are also presented. Finally, simulation results show that
sets of erasure patterns designed using the proposed methods outperform other
algorithms with the same number of decoding trials.Comment: to appear in the IEEE Transactions on Information Theory (Special
Issue on Facets of Coding Theory: from Algorithms to Networks
A Simple Proof of Maxwell Saturation for Coupled Scalar Recursions
Low-density parity-check (LDPC) convolutional codes (or spatially-coupled
codes) were recently shown to approach capacity on the binary erasure channel
(BEC) and binary-input memoryless symmetric channels. The mechanism behind this
spectacular performance is now called threshold saturation via spatial
coupling. This new phenomenon is characterized by the belief-propagation
threshold of the spatially-coupled ensemble increasing to an intrinsic noise
threshold defined by the uncoupled system. In this paper, we present a simple
proof of threshold saturation that applies to a wide class of coupled scalar
recursions. Our approach is based on constructing potential functions for both
the coupled and uncoupled recursions. Our results actually show that the fixed
point of the coupled recursion is essentially determined by the minimum of the
uncoupled potential function and we refer to this phenomenon as Maxwell
saturation. A variety of examples are considered including the
density-evolution equations for: irregular LDPC codes on the BEC, irregular
low-density generator matrix codes on the BEC, a class of generalized LDPC
codes with BCH component codes, the joint iterative decoding of LDPC codes on
intersymbol-interference channels with erasure noise, and the compressed
sensing of random vectors with i.i.d. components.Comment: This article is an extended journal version of arXiv:1204.5703 and
has now been accepted to the IEEE Transactions on Information Theory. This
version adds additional explanation for some details and also corrects a
number of small typo
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