Ferromagnetism in Fe-doped Ba6Ge25 Chiral Clathrate

We have successfully synthesized a Ba6Ge25 clathrate, substituting 3 Fe per formula unit by Ge. This chiral clathrate has Ge sites forming a framework of closed cages and helical tunnel networks. Fe atoms randomly occupy these sites, and exhibit high-spin magnetic moments. A ferromagnetic transition is observed with Tc = 170 K, the highest observed Tc for a magnetic clathrate. However, the magnetic phase is significantly disordered, and exhibits a transformation to a re-entrant spin glass phase. This system has a number of features in common with other dilute magnetic semiconductors.Comment: Submitted to Applied Physics Letters. Fig. 1 resolution reduced for online archive versio

USDA's Livestock Gross Margin Insurance for Dairy: What Is It and How Can It Be Used for Risk Management

Dairy farmers are faced with tremendous and increasing volatility, both in terms of milk prices, and the costs of purchased feed. There is a new weapon in the risk management arsenal of U.S. dairy producers: the Livestock Gross Margin for Dairy (LGM-Dairy) insurance program controls for lower gross revenue, defined as the value of milk produced minus feed costs. This program is administered by USDA's Risk Management Agency, and made available via authorized crop insurance agents to dairy farm operators in the lower 48 states.

Livestock Gross Margin Insurance for Dairy Cattle: An Analysis of Program Performance and Cost under Alternative Policy Configurations

Livestock Gross Margin insurance for dairy cattle (LGM-Dairy) is a risk management tool that can be used to insure a lower bound on a dairy producer’s gross margin. In this paper we (1) review the basic structure of LGM-Dairy (2) examine the sensitivity of Gross Margin Guarantee (GMG) and premium to changes in feeding regimes and (3) quantify impacts of changes in deductible level on important program characteristics.Dairy Price Risk, Uncertainty, Livestock Insurance., Agribusiness, Farm Management, Financial Economics, Livestock Production/Industries, Production Economics, Risk and Uncertainty,

Overcoming the su(2^n) sufficient condition for the coherent control of n-qubit systems

We study quantum systems with even numbers N of levels that are completely state-controlled by unitary transformations generated by Lie algebras isomorphic to sp(N) of dimension N(N+1)/2. These Lie algebras are smaller than the respective su(N) with dimension N^2-1. We show that this reduction constrains the Hamiltonian to have symmetric energy levels. An example of such a system is an n-qubit system. Using a geometric representation for the quantum wave function of a finite system, we present an explicit example that shows a two-qubit system can be controlled by the elements of the Lie algebra sp(4) (isomorphic to spin(5) and so(5)) with dimension ten rather than su(4) with dimension fifteen. These results enable one to envision more efficient algorithms for the design of fields for quantum-state engineering, and they provide more insight into the fundamental structure of quantum control.Comment: 13 pp., 2 figure

Evaluation of flexible barrier and sabo dam to control effects of debris flow in Santo Domingo Ravine

Coast of Peru is characterized for the presence of ephemeral creeks which drain water only on wet season. The extremely dry soil and pebble combined with precipitation produce debris flow in a seasonal geodynamic. This is the case of Santo Domingo ravine which is located at eastern Lima, and drains their water to Rimac River. In this article the vulnerability of villages near to Santo Domingo ravine by debris flow and use of flexible barrier and sabo dams are analyzed. In a first stage, the liquid hydrograph to a 100 years return period was built and a solid hydrograph, a relationship between volume concentration and time, was essayed. Then, both the liquid and the solid hydrograph are calibrated in a debris flow numerical model and the vulnerability map is built. Finally, this model is coupled to the Rimac River to analyze the possible damming effect. Calibration of numerical model was done in base to previous estimated volumes by Japanese International Cooperation Agency (JICA). These first results permit to define high vulnerability zones which will be a reference to evaluate efficiency of control measures. In a second stage, mitigation effects of flexible barriers application is simulated in base to Debris Flow Barrier from Geobrugg®. Also, application of sabo dams was evaluated to by using “Kanako” debris flow simulator from Laboratory of Erosion Control, Division of Forest Science, Graduate School of Agriculture, Kyoto University, & SABO Technical Center. Results permit to evaluate efficiency and select the more economical option

The power of low-resolution spectroscopy: On the spectral classification of planet candidates in the ground-based CoRoT follow-up

Planetary transits detected by the CoRoT mission can be mimicked by a low-mass star in orbit around a giant star. Spectral classification helps to identify the giant stars and also early-type stars which are often excluded from further follow-up. We study the potential and the limitations of low-resolution spectroscopy to improve the photometric spectral types of CoRoT candidates. In particular, we want to study the influence of the signal-to-noise ratio (SNR) of the target spectrum in a quantitative way. We built an own template library and investigate whether a template library from the literature is able to reproduce the classifications. Including previous photometric estimates, we show how the additional spectroscopic information improves the constraints on spectral type. Low-resolution spectroscopy ($R\approx$1000) of 42 CoRoT targets covering a wide range in SNR (1-437) and of 149 templates was obtained in 2012-2013 with the Nasmyth spectrograph at the Tautenburg 2m telescope. Spectral types have been derived automatically by comparing with the observed template spectra. The classification has been repeated with the external CFLIB library. The spectral class obtained with the external library agrees within a few sub-classes when the target spectrum has a SNR of about 100 at least. While the photometric spectral type can deviate by an entire spectral class, the photometric luminosity classification is as close as a spectroscopic classification with the external library. A low SNR of the target spectrum limits the attainable accuracy of classification more strongly than the use of external templates or photometry. Furthermore we found that low-resolution reconnaissance spectroscopy ensures that good planet candidates are kept that would otherwise be discarded based on photometric spectral type alone.Comment: accepted for publication in Astronomische Nachrichten; 12 pages, 4 figures, 7 table