A 20cm VLA Survey of Abell Clusters of Galaxies VI. Radio/Optical Luminosity Functions

From a statistically complete sample of 188 radio galaxies in Abell clusters, we examine the radio/optical correlations, the FR I/II division, and the univariate and bivariate luminosity functions. As suggested by Owen (1993), the FR I/II division is shown to be a strong function of the optical luminosity of the host galaxy (proportional to L_opt^2). This dependence is also seen in the bivariate luminosity function, which suggests that the evolutionary tracks of radio sources and/or the initial conditions in the source are governed by the host galaxy properties. The probability for detecting radio emission increases with optical luminosity. The optical dependence is clearly separated in the integral luminosity functions which can be used as a constraint to models of FR I radio power evolution. Additionally, the source counts from the integrated univariate radio luminosity function (RLF) are consistent with our suggestion in paper V that radio sources may be a transient phenomenon which occurs in all elliptical galaxies at some time (or several times) over their lifetime. We find no statistically significant differences in the luminosity functions between rich cluster samples and radio sources not selected to reside in clusters. These results suggest that all radio galaxies live in similar environments in that the optical luminosity and the properties of the host galaxy are the most important parameters which affect radio source formation and evolution.Comment: 21 pages LaTeX, 3 tables, 12 figures. To appear in July 1996 A

Developments in Aeroengines

This paper reviews developments in aeroengines over the past 70 years from Whittle's first turbojet engine to the current turbofans. Modern turbofan engines are now capable of producing around 440 kN (100,000 Ib) of thrust, compared with 7kN (1600 Ib) for the first turbojet engines, while over this period the specific fuel consumption has halved and the thrust-to-weight ratio has increased significantly. The performance and reliability of these engines have revolutionised both civil and military aeronautics throughout the world. Some of the technical advances that have made these developments possible are described and possible future trends are discussed

The Historical Origins of U.S. Exchange Market Intervention Policy

The present set of arrangements for U.S. exchange market intervention policy was largely developed after 1961 during the Bretton Woods era. However, that set had important historical precedents. In this paper we examine precedents to current arrangements, focusing on three historical eras: pre-1934 operations; the Exchange Stabilization Fund operations beginning in 1934; and the Bretton Woods era. We describe operations by the Second Bank of the United States in the pre-Civil War period and then operations by the U.S. Treasury in the post-Civil War period. After establishment of the Federal Reserve in 1914, the New York Fed engaged in isolated exchange market policies in the 1920s and 1930s, first under the direction of the Governor Benjamin Strong until his death in 1928, thereafter, under the direction of his successor, George Harrison. We then examine operations of the Exchange Stabilization Fund that the Gold Reserve Act of 1934 created as a Treasury Department agency. We exploit unique unpublished sources to analyze its dealings with the Banque de France and the Bank of England before and after the Tripartite Agreement. Finally, based on a unique data set of all U.S. Treasury and Federal Reserve foreign-exchange transactions, we discuss U.S. efforts from 1961 through 1972 to defend the dollar's parity under the Bretton Woods system.

Autism-associated SNPs in the clock genes _npas2_, _per1_ and the homeobox gene _en2_ alter DNA sequences that show characteristics of microRNA genes.

Intronic single nucleotide polymorphisms (SNPs) in the clock genes _npas2_ and _per1_ and the homeobox gene _en2_ are reported to be associated with autism. This bioinformatics analysis of the intronic regions which contain the autism-associated SNPs rs1861972 and rs1861973 in _en2_, rs1811399 in _npas2_, and rs885747 in _per1_, shows that these regions encode RNA transcripts with predicted structural characteristics of microRNAs. These microRNA-like structures are disrupted _in silico_ by the presence of the autism enriched alleles of rs1861972, rs1861973, rs1811399 and rs885747 specifically, as compared with the minor alleles of these SNPs. The predicted gene targets of these microRNA-like structures include genes reported to be implicated in autism (_gabrb3_, _shank3_) and genes causative of diseases co-morbid with autism (_mecp2_ and _rai1_). The inheritance of the AC haplotype of rs1861972 - rs1861973 in _en2_, the C allele of rs1811399 in _npas2_, and the C allele of rs1234747 in _per1_ may contribute to the causes of autism by affecting microRNA genes that are co-expressed along with the homeobox gene _en2_ and the circadian genes _npas2_ and _per1_

On the evolution of U.S. foreign-exchange-market intervention: thesis, theory, and institutions

Attitudes about foreign-exchange-market intervention in the United States evolved in tandem with views about monetary policy as policy makers grappled with the perennial problem of having more economic objectives than independent instruments with which to achieve them. This paper—the introductory chapter to our history of U.S. foreign exchange market intervention—explains this thesis and summarizes our conclusion: The Federal Reserve abandoned frequent foreign-exchange-market intervention because, rather than providing a solution to the instruments-versus-objectives problem, it interfered with the Federal Reserve’s ability to credibly commit to low and stable inflation. This chapter also provides a theoretical discussion of intervention, background on U.S. institutions for conducting intervention, and a roadmap to the remainder of our book.Foreign exchange market ; Monetary policy - United States

Bretton Woods and the U.S. decision to intervene in the foreign-exchange market, 1957-1962

The deterioration in the U.S. balance of payments after 1957 and an accelerating loss of gold reserves prompted U.S. monetary authorities to undertake foreign-exchange-market interventions beginning in 1961. We discuss the events leading up to these interventions, the institutional arrangements developed for that purpose, and the controversies that ensued. Although these interventions forestalled a loss of U.S. gold reserves, in the end, they only delayed more fundamental adjustments and, in that respect, were a failure.Foreign exchange administration ; Bretton Woods Agreements Act