Broadcast Channels with Cooperating Decoders

We consider the problem of communicating over the general discrete memoryless broadcast channel (BC) with partially cooperating receivers. In our setup, receivers are able to exchange messages over noiseless conference links of finite capacities, prior to decoding the messages sent from the transmitter. In this paper we formulate the general problem of broadcast with cooperation. We first find the capacity region for the case where the BC is physically degraded. Then, we give achievability results for the general broadcast channel, for both the two independent messages case and the single common message case.Comment: Final version, to appear in the IEEE Transactions on Information Theory -- contains (very) minor changes based on the last round of review

Analysis of somatic mutations across the kinome reveals loss-of-function mutations in multiple cancer types

AbstractIn this study we use somatic cancer mutations to identify important functional residues within sets of related genes. We focus on protein kinases, a superfamily of phosphotransferases that share homologous sequences and structural motifs and have many connections to cancer. We develop several statistical tests for identifying Significantly Mutated Positions (SMPs), which are positions in an alignment with mutations that show signs of selection. We apply our methods to 21,917 mutations that map to the alignment of human kinases and identify 23 SMPs. SMPs occur throughout the alignment, with many in the important A-loop region, and others spread between the N and C lobes of the kinase domain. Since mutations are pooled across the superfamily, these positions may be important to many protein kinases. We select eleven mutations from these positions for functional validation. All eleven mutations cause a reduction or loss of function in the affected kinase. The tested mutations are from four genes, including two tumor suppressors (TGFBR1 and CHEK2) and two oncogenes (KDR and ERBB2). They also represent multiple cancer types, and include both recurrent and non-recurrent events. Many of these mutations warrant further investigation as potential cancer drivers.</jats:p

Renormalization group maps for Ising models in lattice gas variables

Real space renormalization group maps, e.g., the majority rule transformation, map Ising type models to Ising type models on a coarser lattice. We show that each coefficient of the renormalized Hamiltonian in the lattice gas variables depends on only a finite number of values of the renormalized Hamiltonian. We introduce a method which computes the values of the renormalized Hamiltonian with high accuracy and so computes the coefficients in the lattice gas variables with high accuracy. For the critical nearest neighbor Ising model on the square lattice with the majority rule transformation, we compute over 1,000 different coefficients in the lattice gas variable representation of the renormalized Hamiltonian and study the decay of these coefficients. We find that they decay exponentially in some sense but with a slow decay rate. We also show that the coefficients in the spin variables are sensitive to the truncation method used to compute them.Comment: 22 pages, 9 color postscript figures; minor revisions in version

2004 Presidential Election: Who Won The Popular Vote? An Examination of the Comparative Validity of Exit Poll and Vote Count Data

* There is a substantial discrepancy -- well outside the margin of error and outcomedeterminative -- between the national exit poll and the popular vote count.* The possible causes of the discrepancy would be random error, a skewed exit poll, or breakdown in the fairness of the voting process and accuracy of the vote count.* Analysis shows that the discrepancy cannot reasonably be accounted for by chance or random error.* Evidence does not support hypotheses that the discrepancy was produced by problems with the exit poll.* Widespread breakdown in the fairness of the voting process and accuracy of the vote count are the most likely explanations for the discrepancy.* In an accurate count of a free and fair election, the strong likelihood is that Kerry would have been the winner of the popular vote.This document was originally published by Verified Vote 2004, and is authored by Jonathan Simon, currently with Election Defense Alliance

Productivity and the Euro-Dollar Exchange Rate Puzzle

This paper documents the evidence for a productivity based model of the dollar/euro real exchange rate over the 1985-2001 period. We estimate cointegrating relationships between the real exchange rate, productivity, and the real price of oil using the Johansen (1988) and Stock-Watson (1993) procedures. We find that each percentage point in the US-Euro area productivity differential results in a five percentage point real appreciation of the dollar. This finding is robust to the estimation methodology, the variables included in the regression, and the sample period. We conjecture that productivity-based models cannot explain the observed patterns with the standard set of assumptions, and describe a case in which the model can be reconciled with the observed data.

Structure and Trends of Rural Employment: Canada in the Context of OECD Countries

In 1991, 33 percent of Canada's population lived in predominantly rural regions. Employment growth in rural regions averaged 1.3 percent per year over the 1980s, ranking fourth among OECD countries. In 1991, only 11 percent of the rural workforce in Canada were working in agriculture, forestry or fishing. Within rural regions, employment growth was highest in rural areas adjacent to metropolitan centres. Business services was the fastest growing sector in all types of regions, but rural regions received only a minor boost due to the relatively low share of their workforce in business services. On average, rural areas showed less growth - however, within rural areas, there were regions that showed more growth than urban regions. Rurality does not necessarily imply slow employment growth.Community/Rural/Urban Development, Labor and Human Capital,