A SYSTEM-WIDE APPROACH FOR ANALYZING JAPANESE WHEAT IMPORT ALLOCATION DECISIONS

This paper develops and implements an import allocation model based on Theil's system-wide approach to demand and tests the assumption of blockwise dependence and uniform substitutability among different sources and types of wheat imported by Japan.Crop Production/Industries, International Relations/Trade, Research Methods/ Statistical Methods,

A solar power system for an early Mars expedition

As NASA looks at missions that will expand human presence in the solar system, the power requirements for such missions need to be defined, developed and analyzed. One mission under consideration consists of a 40 day manned Mars surface expedition to perform science experiments. The mission time was centered around an aerocentric longitude (Ls) of 90 deg to lessen the probability of an occurrence of a local or planetary dust storm. The mission site was arbitrarily located at the Martian equator. The power requirements were assumed to be 40 kWe for life support and experiment power during the Martian day and 20 kWe for life support during the Martian night. A solar energy system consisting of roll-out amorphous silicon arrays and a hydrogen-oxygen regenerative fuel cell energy storage system was chosen for the study. The power available from a roll-out array, when plotted against time, approaches a cosine-like curve and depends on both array area and the amount of solar irradiance impinging on its horizontal surface. The array is sized to provide at least 20 KWe when the sun is 12.5 deg above the horizon and ramp up to 140 kWe peak power at Martian noon. In this configuration, the array is capable of supplying 40 KWe continuously to the user for the majority of the Martian day while supplying the excess energy to the electrolyzer portion of the energy storage system. A roll-out, pumped loop radiator system is used to dissipate the waste heat produced by the fuel cell. The power management and distribution system inverts the power from the individual solar array sub-modules and the fuel cell stacks and connects them to a 440 VAC single phase 20 kHz main bus. The total power system is comprised of 80 individual solar array modules with an integral bus and three energy storage modules consisting of fuel cell and electrolyzer stacks, reactant storage tanks, and a roll-out radiator. Power system mass, stowed volume, and deployed area were determined. Day/night power splits of 40/10 kWe, 40/30 kWe, and 40/40 kWe were also considered to determine the impact of a range of nighttime power requirements on the baseline system

THE IMPACT OF THE EXPORT ENHANCEMENT PROGRAM ON INTERNATIONAL FEED BARLEY MARKETS

A "hybrid" spatial price equilibrium model is developed to evaluate differences in trade flows and equilibrium prices for feed and malting barley exports from the U.S., Canada, Australia, and European Union, caused by the U.S. Export Enhancement Program (EEP). The analysis incorporates the relationships among several policy instruments.Demand and Price Analysis, International Relations/Trade,

CHAP Enhances Versatility in Colloidal Probe Fabrication

A colloidal probe, comprising a colloidal particle attached to an atomic force microscope cantilever, is employed to measure directly interaction forces between the particle and a surface. It is possible to change or even destroy a particle while attaching it to a cantilever, thus limiting the types of systems to which the colloidal probe technique may be applied. Here we present the Controlled Heating and Alignment Platform (CHAP) for fabricating colloidal probes without altering the original characteristics of the attached particle. The CHAP applies heat directly to the atomic force microscope chip to rapidly and precisely control cantilever temperature. This minimizes particle heating and enables control over the viscosity of thermoplastic adhesive, to prevent it from contaminating the particle surface. 3D-printed components made the CHAP compatible with standard optical microscopes and streamlined the fabrication process while increasing the platforms versatility. Using the CHAP with a thermoplastic wax adhesive, colloidal probes were fabricated using polystyrene and silica particles between 0.7 and 40 m in diameter. We characterized the properties and interactions of the adhesive and particles, as well as the properties of the completed probes, to demonstrate the retention of particle features throughout fabrication. Pull-off tests with CHAPs probes measured adhesive force values in the expected ranges and demonstrated that particles were firmly attached to the cantilevers

Low-temperature process steps for realization of non-volatile memory devices

In this work, the low-temperature process steps required for the realization of nano-crystal non-volatile memory cells are discussed. An amorphous silicon film, crystallized using a diode pumped solid state green laser irradiating at 532 nm, is proposed as an active layer. The deposition of the subsequent functional layers (e.g., gate oxide) can be done using CVD and ALD reactors in a cluster tool. We show that a high nanocrystal density (Si-NC), required for a good functionality of the memory device, can be obtained by using disilane (Si2H6) or trisilane (Si3H8, known as Silcore®) as precursors for LPCVD instead of silane, at a deposition temperature of 325 °C. The nanocrystals are encapsulated with an ALD-Al2O3 layer (deposited at 300 °C), which serves as oxidation barrier. The passivation of the realized structure is done with an ALD-TiN layer deposited at 425 °C. In this work, we realized Al/TiN/Al2O3/Si-NC/SiO2/Si(100) multilayer floating-gate structures, where the crystallized amorphous silicon film was for the time being replaced by a mono-crystalline silicon wafer, and the gate oxide was thermally grown instead of a low-temperature PECVD oxide. The structures were characterized in terms of their performance as memory cells. In addition, the feasibility to use laser crystallization for improving the amorphous silicon films (prior to the gate oxide deposition) was explored

The spin-wave spectrum of the Jahn-Teller system LaTiO3

We present an analytical calculation of the spin-wave spectrum of the Jahn-Teller system LaTiO3. The calculation includes all superexchange couplings between nearest-neighbor Ti ions allowed by the space-group symmetries: The isotropic Heisenberg couplings and the antisymmetric (Dzyaloshinskii-Moriya) and symmetric anisotropies. The calculated spin-wave dispersion has four branches, two nearly degenerate branches with small zone-center gaps and two practically indistinguishable high-energy branches having large zone-center gaps. The two lower-energy modes are found to be in satisfying agreement with neutron-scattering experiments. In particular, the experimentally detected approximate isotropy in the Brillouin zone and the small zone-center gap are well reproduced by the calculations. The higher-energy branches have not been detected yet by neutron scattering but their zone-center gaps are in satisfying agreement with recent Raman data.Comment: 13 pages, 5 figure

A Direct Elliptic Solver Based on Hierarchically Low-rank Schur Complements

A parallel fast direct solver for rank-compressible block tridiagonal linear systems is presented. Algorithmic synergies between Cyclic Reduction and Hierarchical matrix arithmetic operations result in a solver with $O(N \log^2 N)$ arithmetic complexity and $O(N \log N)$ memory footprint. We provide a baseline for performance and applicability by comparing with well known implementations of the $\mathcal{H}$-LU factorization and algebraic multigrid with a parallel implementation that leverages the concurrency features of the method. Numerical experiments reveal that this method is comparable with other fast direct solvers based on Hierarchical Matrices such as $\mathcal{H}$-LU and that it can tackle problems where algebraic multigrid fails to converge

Sievenpiper HIS and its influence on antenna correlation

This paper deals with the influence of artificial magnetic conductors (AMC), so-called Sievenpiper High Impedance Surfaces (HIS), on the MIMO and Diversity performance of a planar linear-polarized 2×2 dipole array in the ISM-band at 2.45 GHz. The characteristic performance criteria such as envelope correlation coefficient, spectral efficiency, Mean Effective Gain (MEG) and Diversity gain of a coupled 2×2 dipole array are investigated. By means of full-wave electromagnetic analysis as well as Monte-Carlo simulations applying statistical channel models the characteristic antenna pattern just as the MIMO and Diversity analysis is performed, respectively. The obtained results show that the application of Sievenpiper High Impedance Surfaces to planar antenna arrays enables good MIMO and Diversity performance compared to ideal configurations in free-space while offering the design of low profile antennas with simultaneously enhanced characteristics. © Author(s) 2008

TNF and PGE2 in human monocyte-derived macrophages infected with Chlamydia trachomatis

In this study levels of prostaglandin E2 (PGE2), tumour necrosis factor (TNF) and interleukin-1 (IL-1) alpha in medium from monocyte derived macrophages (MdM) infected with Chlamydia trachomatis (L2/434/Bu or K biovars). TNF and PGE2 were found in both cases while IL-1 alpha was not detected. Both TNF and PGE2 levels were higher in the medium of the MdM infected with K biovars. TNF reached maximum levels 24 h postinfection, and then declined, while PGE2 levels increased continuously during the infection time up to 96 h post-infection. Addition of dexamethasone inhibited production of TNF and PGE2. Inhibition of PGE2 production by indomethacin resulted in increased production of TNF, while addition of PGE2 caused partial inhibition of TNF production from infected MdM