The Base Engine for Solar Stirling Power

A new concept in Stirling engine technology is embodied in the base engine now being developed at Stirling Thermal Motors, Inc. This is a versatile energy conversion unit suitable for many different applications and heat sources. The base engine, rated 40 kW at 2800 RPM, is a four-cylinder, double-acting variable displacement Stirling engine with pressurized crankcase and rotating shaft seal. Remote-heating technology is incorporated with a stacked-heat-exchanger configuration and a liquid metal heat pipe connected to a distinctly separate combustor or other heat source. High efficiency over a wide range of operating conditions, long life, low manufacturing cost and low material cost are specifically emphasized. The base engine, its design philosophy and approach, its projected performance, and some of its more attractive applications are described

Coexistence of bulk and surface states probed by Shubnikov-de Haas oscillations in Bi2_2Se3_3 with high charge-carrier density

Topological insulators are ideally represented as having an insulating bulk with topologically protected, spin-textured surface states. However, it is increasingly becoming clear that these surface transport channels can be accompanied by a finite conducting bulk, as well as additional topologically trivial surface states. To investigate these parallel conduction transport channels, we studied Shubnikov-de Haas oscillations in Bi$_2$Se$_3$ thin films, in high magnetic fields up to 30 T so as to access channels with a lower mobility. We identify a clear Zeeman-split bulk contribution to the oscillations from a comparison between the charge-carrier densities extracted from the magnetoresistance and the oscillations. Furthermore, our analyses indicate the presence of a two-dimensional state and signatures of additional states the origin of which cannot be conclusively determined. Our findings underpin the necessity of theoretical studies on the origin of and the interplay between these parallel conduction channels for a careful analysis of the material's performance.Comment: Manuscript including supplemental materia

Helicity Amplitudes for Charmonium Production in Hadron-Hadron and Photon-Hadron Collisions

We present the gluon-gluon and photon-gluon helicity amplitudes for color singlet and octet charmonium production in polarized and unpolarized hadron-hadron and photon-hadron collisions.Comment: 11 pages amstex no figure

An Experiment Concerning Partly Closed Cavities Behind a Surface-Piercing Rod

Thomsen in Ref. (1) emphasizes three different states of ventilation occurring at surface-piercing rods, as observed by Hay (2). Hay has towed cylindrical rods which intersect the water surface, at different speeds and at different depths of submergence. From his photographic records, the following observations have been made. At relatively low speeds, an air filled cavity is formed in the wake of the rod, which is open to atmosphere and which extends downwards to a point above the base of the rod. With increasing speed, this point moves downward towards the base of the rod. This form of cavity has been called the "Pre-Base Ventilation State". After the cavity has reached the base, the state was referred to as the "Base Ventilation State", which is found to persist with further increased speed. After the speed was increased over a certain level, the size of the cavity was observed to decrease again forming a cavity closed at the water surface. In this case the state was called the "Post-Base Ventilation State". Since this last phase in the development of the air-cavity has not been observed in the Free Surface Water Tunnel at the California Institute of Technology, it was thought desirable to perform some experiments in order to find the conditions under which this Post-Base Ventilation State can occur. The present results are to be regarded as preliminary. A full explanation of the ventilation phenomena described in the references above and the text of this report to follow is not yet available. Nevertheless, since the results of the present work are at variance with published work, it was thought worthwhile to present them now. Hopefully a more thorough understanding of the ventilation phenomena will be obtained in the not too distant future

Competition between Spin-Orbit Interaction and Zeeman Coupling in Rashba 2DEGs

We investigate systematically how the interplay between Rashba spin-orbit interaction and Zeeman coupling affects the electron transport and the spin dynamics in InGaAs-based 2D electron gases. From the quantitative analysis of the magnetoconductance, measured in the presence of an in-plane magnetic field, we conclude that this interplay results in a spin-induced breaking of time reversal symmetry and in an enhancement of the spin relaxation time. Both effects, due to a partial alignment of the electron spin along the applied magnetic field, are found to be in excellent agreement with recent theoretical predictions.Comment: 4 figures and 4 page

Fish to 2020: supply and demand in changing global markets

Using a state-of-the art computer model of global supply and demand for food and feed commodities, this book projects the likely changes in the fisheries sector over the next two decades. As prices for most food commodities fall, fish prices are expected to rise, reflecting demand for fish that outpaces the ability of the world to supply it. The model shows that developing countries will consume and produce a much greater share of the world's fish in the future, and trade in fisheries commodities will also increase. The authors show the causes and implications of these and other changes, and argue for specific actions and policies that can improve outcomes for the poor and for the environment.Supply balance, Trade, Aquaculture, Fishery management, Economic analysis, Environmental factors, Developing countries