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&

Uni-directional polymerization leading to homochirality in the RNA world

The differences between uni-directional and bi-directional polymerization are considered. The uni-directional case is discussed in the framework of the RNA world. Similar to earlier models of this type, where polymerization was assumed to proceed in a bi-directional fashion (presumed to be relevant to peptide nucleic acids), left-handed and right-handed monomers are produced via an autocatalysis from an achiral substrate. The details of the bifurcation from a racemic solution to a homochiral state of either handedness is shown to be remarkably independent of whether the polymerization in uni-directional or bi-directional. Slightly larger differences are seen when dissociation is allowed and the dissociation fragments are being recycled into the achiral substrate.Comment: 9 pages, 4 figures, submitted to Astrobiolog

Mesoscopic Thermovoltage Measurement Design

Quantitative thermoelectric measurements in the mesoscopic regime require accurate knowledge of temperature, thermovoltage, and device energy scales. We consider the effect of a finite load resistance on thermovoltage measurements of InAs/InP heterostructure nanowires. Load resistance and ac attenuation distort the measured thermovoltage therefore complicating the evaluation of device performance. Understanding these effects improves experimental design and data interpretation.Comment: 2 pages, 3 figure

Forest Phytomass and Carbon in European Russia.

Regression equations for basic fractions of forest phytomass have been developed for the European-Ural part of Russia based on available experimental data and publications (preliminarily examined 962 sample plots and aggregations). 8 main forest forming species (pine, spruce, oak, birch, beech, aspen, alder, lime) which were involved into analysis cover in European Russia about 95% of total forested areas. The equations allow to evaluate the ratio between phytomass fractions weight and growing stock by species, age and site indexes. The application of the equations to the Forest State Account data (1988) gives the total (living) phytomass in forest ecosystems of European Russia (forested area of 166.0 Mha, growing stock of 20.28 bln m3) of 15.47 Pg drt matter (density 9.32 kg/m2). The total carbon pool was estimated 7.64 Pg C with average density 4.60 kg C/m2 in 1988. Analysis of uncertainties of data and used methods showed that the results which based on FSA data probably underestimate real values for about 5% with standard error +/- 7-8% with confidential (apriori) probability 0.8-0.9. Used this assumption unbiased estimate of total storage of phytomass in forest vegetation were calculated for 1993 of 16.94 Pg (average density 10.36 kg/m2 ) and for C content respectively (8.37 Tg and 5.03 kg/m2 repectively). The changes of forest phytomass in 1966-1993 were esimated of 4.73 Pg (or about 174 Tg of dry matter/year) and for C - 2.34 Pg, i.e. the European Russian forests provided during 1966-1993 net sink of carbon in forest vegetation about 87 Tg C annually.

PRODUCT AND PROCESS CERTIFICATION IN IMPERFECTLY COMPETITIVE MARKETS

Consumers, policy makers, and business decision makers are increasingly concerned about food safety and security. In the U.S. meat industry, certification programs could address some of these problems. This study builds a three-sector partial equilibrium model to analyze the distributional effects of implementing a certification program for meat product.Food Consumption/Nutrition/Food Safety,

Certification of Pork Products

The objective of this paper is to provide insights on the welfare distributional impact on consumer and producer welfare resulting from the development and implementation of a credence certification program in the U.S. pork sector. The certification program can provide various levels of tracking and tracing in the marketing chain. The modeling framework follows that of Nilsson (2005), which encompasses product differentiation and substitution across meat products at the consumer level and across live animal types at the farm level. Processors and retailers have potentially bilateral market power and can supply either or both certified and conventional meat products. One of the key findings is that while as the conventional market contracts and the certified market expands as expected, the magnitude depends on whether suppliers are single-or multiproduct providers. On aggregate, total welfare increases by 15 to 24 percent depending on industry structure.Marketing,

A 3+1 Decomposition of the Minimal Standard-Model Extension Gravitational Sector

The 3+1 (ADM) formulation of General Relativity is used in, for example, canonical quantum gravity and numerical relativity. Here we present a 3+1 decomposition of the minimal Standard-Model Extension gravity Lagrangian. By choosing the leaves of foliation to lie along a timelike vector field we write the theory in a form which will allow for comparison and matching to other gravity models.Comment: Presented at the Eighth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, May 12-16, 201

Electrically detected interferometry of Majorana fermions in a topological insulator

We show how a chiral Dirac fermion (a massless electron or hole) can be converted into a pair of neutral chiral Majorana fermions (a particle equal to its own antiparticle). These two types of fermions exist on the metallic surface of a topological insulator, respectively, at a magnetic domain wall and at a magnet-superconductor interface. Interferometry of Majorana fermions is a key operation in topological quantum computation, but the detection is problematic since these particles have no charge. The Dirac-Majorana converter enables electrical detection of the interferometric signal.Comment: 4 pages, 2 figure