Parallel versus sequential updating for Belief Propagation decoding

sequential updating scheme (SUS) for the belief propagation algorithm is proposed, and is compared with the parallel (regular) updating scheme (PUS). Simulation results on various codes indicate that the number of iterations of the belief algorithm for the SUS is about one half of the required iterations for the PUS, where both decoding algorithms have the same error correction properties. The complexity per iteration for both schemes is similar, resulting in a lower total complexity for the SUS. The explanation of this effect is related to the inter-iteration information sharing, which is a property of only the SUS, and which increases the "correction gain" per iterationComment: 15 pages, 3 figures, submitted to Phys. Rev. E june 200

E-commerce and sales taxes: What you collect depends on where you ship

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Panics and Principles: A History of Drug Education Policy in New South Wales 1965-1999

When the problem of young people using illegal drugs for recreation emerged in New South Wales in the 1960s drug education was promoted by governments and experts as a humane alternative to policing. It developed during the 1970s and 1980s as the main hope for preventing drug problems amongst young people in the future. By the 1990s drug policy experts, like their temperance forbears, had become disillusioned with drug education, turning to legislative action for the prevention of alcohol and other drug problems. However, politicians and the community still believed that education was the best solution. Education Departments, reluctant to expose schools to public controversy, met minimal requirements. This thesis examines the ideas about drugs, education and youth that influenced the construction and implementation of policies about drug education in New South Wales between 1965 and 1999. It also explores the processes that resulted in the defining of drug problems and beliefs about solutions, identifying their contribution to policy and the way in which this policy was implemented. The thesis argues that the development of drug education over the last fifty years has been marked by three main cycles of moral panic about youth drug use. It finds that each panic was triggered by the discovery of the use of a new illegal substance by a youth subculture. Panics continued, however, because of the tension between two competing notions of young people’s drug use. In the traditional dominant view ‘drug’ meant illegal drugs, young people’s recreational drug use was considered to be qualitatively different to that of adults, and illegal drugs were the most serious and concerning problem. In the newer alternative ‘public health’ view which began developing in the 1960s, illicit drug use was constructed as part of normal experimentation, alcohol, tobacco and prescribed medicines were all drugs, and those who developed problems with their use were sick, not bad. These public health principles were formulated in policy documents on many occasions. The cycles of drug panic were often an expression of anxiety about the new approach and they had the effect of reasserting the dominant view. The thesis also finds that the most significant difference between the two discourses lies in the way that alcohol is defined, either as a relatively harmless beverage or as a drug that is a major cause of harm. Public health experts have concluded that alcohol poses a much greater threat to the health and safety of young people than illegal drugs. However, parents, many politicians and members of the general community have believed for the last fifty years that alcohol is relatively safe. Successive governments have been influenced by the economic power of the alcohol industry to support the latter view. Thus the role of alcohol and its importance to the economy in Australian society is a significant hindrance in reconciling opposing views of the drug problem and developing effective drug education. The thesis concludes that well justified drug education programs have not been implemented fully because the rational approaches to drug education developed by experts have not been supported by the dominant discourse about the drug problem. Politicians have used drug education as a populist strategy to placate fear but the actual programs that have been developed attempt to inform young people and the community about the harms and benefits of all drugs. When young people take up the use of a new mood altering drug, the rational approach developed by public health experts provokes intense anxiety in the community and the idea that legal substances such as alcohol, tobacco and prescribed drugs can cause serious harm to young people is rejected in favour of an approach that emphasizes the danger of illegal drug use

The Demographics, Stellar Populations, and Star Formation Histories of Fast Radio Burst Host Galaxies: Implications for the Progenitors

We present a comprehensive catalog of observations and stellar population properties for 23 highly secure host galaxies of fast radio bursts (FRBs). Our sample comprises 6 repeating FRBs and 17 apparent nonrepeaters. We present 82 new photometric and 8 new spectroscopic observations of these hosts. Using stellar population synthesis modeling and employing nonparametric star formation histories (SFHs), we find that FRB hosts have a median stellar mass of ≈109.9M⊙, mass-weighted age ≈5.1 Gyr, and ongoing star formation rate ≈1.3 M⊙ yr−1 but span wide ranges in all properties. Classifying the hosts by degree of star formation, we find that 87% (20 of 23 hosts) are star-forming, two are transitioning, and one is quiescent. The majority trace the star-forming main sequence of galaxies, but at least three FRBs in our sample originate in less-active environments (two nonrepeaters and one repeater). Across all modeled properties, we find no statistically significant distinction between the hosts of repeaters and nonrepeaters. However, the hosts of repeating FRBs generally extend to lower stellar masses, and the hosts of nonrepeaters arise in more optically luminous galaxies. While four of the galaxies with the clearest and most prolonged rises in their SFHs all host repeating FRBs, demonstrating heightened star formation activity in the last ≲100 Myr, one nonrepeating host shows this SFH as well. Our results support progenitor models with short delay channels (i.e., magnetars formed via core-collapse supernova) for most FRBs, but the presence of some FRBs in less-active environments suggests a fraction form through more delayed channels

Taxonomic surrogacy in biodiversity assessments, and the meaning of Linnaean ranks

Copyright © 2006 The Natural History MuseumThe majority of biodiversity assessments use species as the base unit. Recently, a series of studies have suggested replacing numbers of species with higher ranked taxa (genera, families, etc.); a method known as taxonomic surrogacy that has an important potential to save time and resources in assesments of biological diversity. We examine the relationships between taxa and ranks, and suggest that species/higher taxon exchanges are founded on misconceptions about the properties of Linnaean classification. Rank allocations in current classifications constitute a heterogeneous mixture of various historical and contemporary views. Even if all taxa were monophyletic, those referred to the same rank would simply denote separate clades without further equivalence. We conclude that they are no more comparable than any other, non-nested taxa, such as, for example, the genus Rattus and the phylum Arthropoda, and that taxonomic surrogacy lacks justification. These problems are also illustrated with data of polychaetous annelid worms from a broad-scale study of benthic biodiversity and species distributions in the Irish Sea. A recent consensus phylogeny for polychaetes is used to provide three different family-level classifications of polychaetes. We use families as a surrogate for species, and present Shannon–Wiener diversity indices for the different sites and the three different classifications, showing how the diversity measures rely on subjective rank allocations.Y. Bertrand, F. Pleijel and G. W. Rous

Supermassive Black Hole Binaries: The Search Continues

Gravitationally bound supermassive black hole binaries (SBHBs) are thought to be a natural product of galactic mergers and growth of the large scale structure in the universe. They however remain observationally elusive, thus raising a question about characteristic observational signatures associated with these systems. In this conference proceeding I discuss current theoretical understanding and latest advances and prospects in observational searches for SBHBs.Comment: 17 pages, 4 figures. To appear in the Proceedings of 2014 Sant Cugat Forum on Astrophysics. Astrophysics and Space Science Proceedings, ed. C.Sopuerta (Berlin: Springer-Verlag

An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types