Laboratory oscillator strengths of Sc I in the near-infrared region for astrophysical applications

Context. Atomic data is crucial for astrophysical investigations. To understand the formation and evolution of stars, we need to analyse their observed spectra. Analysing a spectrum of a star requires information about the properties of atomic lines, such as wavelengths and oscillator strengths. However, atomic data of some elements are scarce, particularly in the infrared region, and this paper is part of an effort to improve the situation on near-IR atomic data. Aims. This paper investigates the spectrum of neutral scandium, Sc i, from laboratory measurements and improves the atomic data of Sc i lines in the infrared region covering lines in R, I, J, and K bands. Especially, we focus on measuring oscillator strengths for Sc i lines connecting the levels with 4p and 4s configurations. Methods. We combined experimental branching fractions with radiative lifetimes from the literature to derive oscillator strengths (f - values). Intensity-calibrated spectra with high spectral resolution were recorded with Fourier transform spectrometer from a hollow cathode discharge lamp. The spectra were used to derive accurate oscillator strengths and wavelengths for Sc i lines, with emphasis on the infrared region. Results. This project provides the first set of experimental Sc i lines in the near-infrared region for accurate spectral analysis of astronomical objects. We derived 63 log(g f ) values for the lines between 5300{\AA} and 24300{\AA}. The uncertainties in the f -values vary from 5% to 20%. The small uncertainties in our values allow for an increased accuracy in astrophysical abundance determinations.Comment: Accepted on 25 August 2015 by A&

The FERRUM project: Experimental lifetimes and transition probabilities from highly excited even 4d levels in Fe ii

We report lifetime measurements of the 6 levels in the 3d6(5D)4d e6G term in Fe ii at an energy of 10.4 eV, and f -values for 14 transitions from the investigated levels. The lifetimes were measured using time-resolved laser-induced fluorescence on ions in a laser-produced plasma. The high excitation energy, and the fact that the levels have the same parity as the the low-lying states directly populated in the plasma, necessitated the use of a two-photon excitation scheme. The probability for this process is greatly enhanced by the presence of the 3d6(5D)4p z6F levels at roughly half the energy difference. The f -values are obtained by combining the experimental lifetimes with branching fractions derived using relative intensities from a hollow cathode discharge lamp recorded with a Fourier transform spectrometer. The data is important for benchmarking atomic calculations of astrophysically important quantities and useful for spectroscopy of hot stars.Comment: A&A, accepte

Inflation Uncertainty and Interest Rates: Theory and Empirical Tests

This paper develops two models, one involving risk neutrality and the other risk aversion, which suggest that inflation uncertainty affects interest rates. Both models give rise to essentially the same interest rate equation for estimation. Empirical evidence supports the hypothesis that inflation uncertainty affects interest rates. Interpreted in terms of the risk neutral model, the empirical results suggest that inflation uncertainty has a negative impact on nominal interest rates and a positive impact on the expected real rate. If the results are interpreted in terms of the risk averse model, inflation uncertainty has a negative impact on nominal interest rates. The expected real rate is not of direct interest in a risk averse world. The results raise real questions about the use of the Fisherian definition of the real interest rate in situations when there is uncertainty about inflation rates. It is argued that even with risk neutrality the Fisherian definition of the real rate is not the appropriate concept upon which to base economic decisions if inflation uncertainty is present. The appropriate concept is an expected real rate which involves an adjustment for uncertainty. Moreover, if the world is risk averse, the expected real rate is not a relevant concept for economic decisions.

A Plan of Farm Organization for Hill Land Farms in Southeastern Ohio

Exact date of bulletin unknown.PDF pages: 2

PDEs in Moving Time Dependent Domains

In this work we study partial differential equations defined in a domain that moves in time according to the flow of a given ordinary differential equation, starting out of a given initial domain. We first derive a formulation for a particular case of partial differential equations known as balance equations. For this kind of equations we find the equivalent partial differential equations in the initial domain and later we study some particular cases with and without diffusion. We also analyze general second order differential equations, not necessarily of balance type. The equations without diffusion are solved using the characteristics method. We also prove that the diffusion equations, endowed with Dirichlet boundary conditions and initial data, are well posed in the moving domain. For this we show that the principal part of the equivalent equation in the initial domain is uniformly elliptic. We then prove a version of the weak maximum principle for an equation in a moving domain. Finally we perform suitable energy estimates in the moving domain and give sufficient conditions for the solution to converge to zero as time goes to infinity.Comment: pp 559-577. Without Bounds: A Scientific Canvas of Nonlinearity and Complex Dynamics (2013) p. 36

Genome-scale metabolic modelling of Salmonella and Lactobacillus species

Salmonella Typhimurium is a major cause of morbidity and mortality in humans. It is also a commonly used model organism for intracellular Gram negative pathogens, a group of bacteria that is becoming increasingly resistant to available antibiotics. Systemic Salmonella infection involves proliferation in the small intestine followed by infection of epithelial and later macrophage host cells. In order to advance the understanding of the r^ole of metabolism in virulence, a genome-scale metabolic model of S. Typhimurium was constructed, based on genomic and biochemical data obtained from public databases. A method for modelling metabolic interactions between cells was developed and applied to models of S. Typhimurium and the probiotic Lactobacillus plan-tarum, in order to simulate the intestinal stage of infection. The analysis indicated that interactions, involving the transfer of glycolate from L. plantarum to S. Typhimurium, that favour growth of S. Typhimurium, are possible, by unlikely to occur in vivo. Data from Phenotype Microarray (PM), as well as DNA microarray data obtained during infection of cultured macrophage cells, was integrated with the S. Typhimurium model. The PM data was largely in agreement with model results for growth on carbon and nitrogen sources, and indicated moderate agreement for sulphur and phosphorus sources. A model-based method for analysis of nutrient availability during growth inside host cells, based on PM and DNA microarray data, was developed. This environment is poorly characterised and direct experimental methods for obtaining this information are not available. The analysis indicated a nutritionally complex host environment, dominated by glycerol 3-phosphate and certain nucleosides and amino acids. Owing to the complexity of the host environment, a method for identication of a sub-network of the model, required for viability on all growth supporting carbon sources was developed. The impact of sequentially removing combinations of reactions in the sub-network from the genome-scale model was evaluated. This analysis suggested approximately 60 reactions that in various combinations could be of relevance for designing antimicrobial intervention strategies, including antimicrobial agents and live attenuated vaccines

Observation of the Cosmic Ray Electron- Positron Ratio from 100 Mev to 3 Bev in 1964

Balloon flight data on cosmic ray electron- positron ratio from 100 MeV to 3 Be

Conceptual designs for in situ analysis of Mars soil

A goal of this research is to develop conceptual designs for instrumentation to perform in situ measurements of the Martian soil in order to determine the existence and nature of any reactive chemicals. Our approach involves assessment and critical review of the Viking biology results which indicated the presence of a soil oxidant, an investigation of the possible application of standard soil science techniques to the analysis of Martian soil, and a preliminary consideration of non-standard methods that may be necessary for use in the highly oxidizing Martian soil. Based on our preliminary analysis, we have developed strawman concepts for standard soil analysis on Mars, including pH, suitable for use on a Mars rover mission. In addition, we have devised a method for the determination of the possible strong oxidants on Mars