Improved source of infrared radiation for spectroscopy

Radiation from a crimped V-groove in the electrically heated metallic element of a high-resolution infrared spectrometer is more intense than that from plane areas adjacent to the element. Radiation from the vee and the flat was compared by alternately focusing on the entrance slit of a spectrograph

Democratization’s Risk Premium: Partisan and Opportunistic Political Business Cycle Effects on Sovereign Ratings in Developing Countries

We use partisan and opportunistic political business cycle (“PBC”) considerations to develop a framework for explaining election-period decisions by credit rating agencies (“agencies”) publishing developing country sovereign risk-ratings (“ratings”). We test six hypotheses derived from the framework with 482 agency ratings for 19 countries holding 39 presidential elections from 1987-2000. We find that ratings are linked to the partisan orientation of incumbents facing election and to expectations of incumbent victory. Consistent with the framework, rating effects are sometimes greater for right-wing compared to left-wing incumbents, perhaps, because partisan PBC considerations with right-wing (left-wing) incumbents reinforce (counteract) opportunistic PBC considerations.http://deepblue.lib.umich.edu/bitstream/2027.42/39931/3/wp546.pd

DEMOCRACY’S SPREAD: Elections and Sovereign Debt in Developing Countries

We use partisan and opportunistic political business cycle (“PBC”) considerations to develop and test a framework for explaining election-period changes in credit spreads for developing country sovereign bonds. Pre-election bond spread trends are significantly linked both to the partisan orientation of incumbents facing election and to expectations of incumbent victory. Bond spreads for right-wing (leftwing) incumbents increase (decrease) as the likelihood of left-wing (right-wing) challenger victory increases. For right-wing incumbent partisan and opportunistic PBC effects bondholder risk perceptions are mutually reinforcing. For left-wing incumbents partisan PBC effects dominate bondholder risk perceptions compared to opportunistic PBC effects.http://deepblue.lib.umich.edu/bitstream/2027.42/39961/3/wp575.pd

Democratization’s Risk Premium: Partisan and Opportunistic Political Business Cycle Effects on Sovereign Ratings in Developing Countries

We use partisan and opportunistic political business cycle (“PBC”) considerations to develop a framework for explaining election-period decisions by credit rating agencies (“agencies”) publishing developing country sovereign risk-ratings (“ratings”). We test six hypotheses derived from the framework with 482 agency ratings for 19 countries holding 39 presidential elections from 1987-2000. We find that ratings are linked to the partisan orientation of incumbents facing election and to expectations of incumbent victory. Consistent with the framework, rating effects are sometimes greater for right-wing compared to left-wing incumbents, perhaps, because partisan PBC considerations with right-wing (left-wing) incumbents reinforce (counteract) opportunistic PBC considerations.economics, elections, developing countries, ratings

Differentiation of regions with atypical oligonucleotide composition in bacterial genomes

BACKGROUND: Complete sequencing of bacterial genomes has become a common technique of present day microbiology. Thereafter, data mining in the complete sequence is an essential step. New in silico methods are needed that rapidly identify the major features of genome organization and facilitate the prediction of the functional class of ORFs. We tested the usefulness of local oligonucleotide usage (OU) patterns to recognize and differentiate types of atypical oligonucleotide composition in DNA sequences of bacterial genomes. RESULTS: A total of 163 bacterial genomes of eubacteria and archaea published in the NCBI database were analyzed. Local OU patterns exhibit substantial intrachromosomal variation in bacteria. Loci with alternative OU patterns were parts of horizontally acquired gene islands or ancient regions such as genes for ribosomal proteins and RNAs. OU statistical parameters, such as local pattern deviation (D), pattern skew (PS) and OU variance (OUV) enabled the detection and visualization of gene islands of different functional classes. CONCLUSION: A set of approaches has been designed for the statistical analysis of nucleotide sequences of bacterial genomes. These methods are useful for the visualization and differentiation of regions with atypical oligonucleotide composition prior to or accompanying gene annotation

Statistics of reversible bond dynamics observed in force-clamp spectroscopy

We present a detailed analysis of two-state trajectories obtained from force-clamp spectroscopy (FCS) of reversibly bonded systems. FCS offers the unique possibility to vary the equilibrium constant in two-state kinetics, for instance the unfolding and refolding of biomolecules, over many orders of magnitude due to the force dependency of the respective rates. We discuss two different kinds of counting statistics, the event-counting usually employed in the statistical analysis of two-state kinetics and additionally the so-called cycle-counting. While in the former case all transitions are counted, cycle-counting means that we focus on one type of transitions. This might be advantageous in particular if the equilibrium constant is much larger or much smaller than unity because in these situations the temporal resolution of the experimental setup might not allow to capture all transitions of an event-counting analysis. We discuss how an analysis of FCS data for complex systems exhibiting dynamic disorder might be performed yielding information about the detailed force-dependence of the transition rates and about the time scale of the dynamic disorder. In addition, the question as to which extent the kinetic scheme can be viewed as a Markovian two-state model is discussed.Comment: 25 pages, 10 figures, Phys. Rev. E, in pres

Global features of sequences of bacterial chromosomes, plasmids and phages revealed by analysis of oligonucleotide usage patterns

BACKGROUND: Oligonucleotide frequencies were shown to be conserved signatures for bacterial genomes, however, the underlying constraints have yet not been resolved in detail. In this paper we analyzed oligonucleotide usage (OU) biases in a comprehensive collection of 155 completely sequenced bacterial chromosomes, 316 plasmids and 104 phages. RESULTS: Two global features were analyzed: pattern skew (PS) and variance of OU deviations normalized by mononucleotide content of the sequence (OUV). OUV reflects the strength of OU biases and taxonomic signals. PS denotes asymmetry of OU in direct and reverse DNA strands. A trend towards minimal PS was observed for almost all complete sequences of bacterial chromosomes and plasmids, however, PS was substantially higher in separate genomic loci and several types of plasmids and phages characterized by long stretches of non-coding DNA and/or asymmetric gene distribution on the two DNA strands. Five of the 155 bacterial chromosomes have anomalously high PS, of which the chromosomes of Xylella fastidiosa 9a5c and Prochlorococcus marinus MIT9313 exhibit extreme PS values suggesting an intermediate unstable state of these two genomes. CONCLUSIONS: Strand symmetry as indicated by minimal PS is a universally conserved feature of complete bacterial genomes that results from the matching mutual compensation of local OU biases on both replichors while OUV is more a taxon specific feature. Local events such as inversions or the incorporation of genome islands are balanced by global changes in genome organization to minimize PS that may represent one of the leading evolutionary forces driving bacterial genome diversification

Study of radiative aspects of lunar materials Final report, 26 Apr. 1966 - 26 Jan. 1967

Numerical calculations and derivation of photometric functions, and mathematical model for infrared radiation from lunar surfac

Correlations in Hot Dense Helium

Hot dense helium is studied with first-principles computer simulations. By combining path integral Monte Carlo and density functional molecular dynamics, a large temperature and density interval ranging from 1000 to 1000000 K and 0.4 to 5.4 g/cc becomes accessible to first-principles simulations and the changes in the structure of dense hot fluids can be investigated. The focus of this article are pair correlation functions between nuclei, between electrons, and between electrons and nuclei. The density and temperature dependence of these correlation functions is analyzed in order to describe the structure of the dense fluid helium at extreme conditions.Comment: accepted for publication in Journal of Physics

Contribution of the massive photon decay channel to the neutrino cooling of neutron stars

The role of the massive photon decay via intermediate states of electron-electron-holes and proton-proton-holes into neutrino-anti-neutrino pairs in the course of neutron star cooling is investigated. These reactions may ba operative in hot neutron stars in the region of proton pairing. The corresponding contribution to the neutrino emissivity is calculated. It varies with the temperature as T3/2e−mγ/T for T < m γ, where mγ is an effective photon mass in superconducting matter. Estimates show that this process appears as strong cooling channel of neutron stars at temperatures T ≈ ( 10^9 - 10^10) K