Genome-wide high-resolution mapping of UV-induced mitotic recombination events in Saccharomyces cerevisiae.

In the yeast Saccharomyces cerevisiae and most other eukaryotes, mitotic recombination is important for the repair of double-stranded DNA breaks (DSBs). Mitotic recombination between homologous chromosomes can result in loss of heterozygosity (LOH). In this study, LOH events induced by ultraviolet (UV) light are mapped throughout the genome to a resolution of about 1 kb using single-nucleotide polymorphism (SNP) microarrays. UV doses that have little effect on the viability of diploid cells stimulate crossovers more than 1000-fold in wild-type cells. In addition, UV stimulates recombination in G1-synchronized cells about 10-fold more efficiently than in G2-synchronized cells. Importantly, at high doses of UV, most conversion events reflect the repair of two sister chromatids that are broken at approximately the same position whereas at low doses, most conversion events reflect the repair of a single broken chromatid. Genome-wide mapping of about 380 unselected crossovers, break-induced replication (BIR) events, and gene conversions shows that UV-induced recombination events occur throughout the genome without pronounced hotspots, although the ribosomal RNA gene cluster has a significantly lower frequency of crossovers

Rapid algorithm for identifying backbones in the two-dimensional percolation model

We present a rapid algorithm for identifying the current-carrying backbone in the percolation model. It applies to general two-dimensional graphs with open boundary conditions. Complemented by the modified Hoshen-Kopelman cluster labeling algorithm, our algorithm identifies dangling parts using their local properties. For planar graphs, it finds the backbone almost four times as fast as Tarjan's depth-first-search algorithm, and uses the memory of the same size as the modified Hoshen-Kopelman algorithm. Comparison with other algorithms for backbone identification is addressed.Comment: 5 pages with 5 eps figures. RevTeX 3.1. Clarify the origin of the hull-generating algorith

Are Macroeconomic Forecasts Informative? Cointegration Evidence from the ASA-NBER Surveys

We examine the properties of the ASA-NBER forecasts for several US macroeconomic variables, specifically: (i) are the actual and forecast series integrated of the same order; (ii) are they cointegrated, and; (iii) is the cointegrating vector consistent with long run unitary elasticity of expectations with respect to the actual series. We also examine whether forecasts respond to error correction terms. Tests are applied to both final and preliminary versions of the data. We find that the Treasury bill rate, housing starts, industrial production, inflation and their forecasts are trend stationary. The corporate bond rate, GNP, the GNP deflator, unemployment and their forecasts are difference stationary. About half of the these pairs are cointegrated, with the unitary elasticity restriction seldom rejected. Similar results are obtained when using the originally-reported data.

Currency Traders and Exchange Rate Dynamics: A Survey of the U.S. Market

We report findings from a survey of United States foreign exchange traders. Our results indicate that: (i) in recent years electronically-brokered transactions have risen substantially, mostly at the expense of traditional brokers; (ii) the market norm is an important det e rminant of interbank bid-ask spread and the most widely-cited reason for deviating from the conventional bid-ask spread is a thin/hectic market; (iii) half or more of market respondents believe that large players dominate in the dollar-pound and dollar-Swiss franc markets; (iv) technical trading best characterizes about 30% of traders, with this proportion rising from five years ago; (v) news about macroeconomic variables is rapidly incorporated into exchange rates; (vi) the importance of individual macroe c onomic variables shifts over time, although interest rates always appear to be important; (vii) economic fundamentals are perceived to be more important at longer horizons, while short-run deviations from the fundamentals are attributed to excess speculation and institutional customer/hedge fund manipulation; (viii) speculation is generally viewed positively, as enhancing market efficiency and liquidity, even though it exacerbates volatility; (ix) central bank intervention does not appear to have substantial effect, although there is general agreement that it increases volatility, and finally; (x) traders do not view purchasing power parity as a useful concept, even though a significant proportion (40%) believe that it affects exchange rates at horizons of over six months.