2,607 research outputs found
ALTERNATIVE METHODS OF ACCOUNTING FOR LIVESTOCK CAPITAL FORMATION: AN APPLICATION TO SOUTHERN U.S. AGRICULTURE
Livestock Production/Industries,
Results from a set of three-dimensional numerical experiments of a hot Jupiter atmosphere
We present highlights from a large set of simulations of a hot Jupiter
atmosphere, nominally based on HD 209458b, aimed at exploring both the
evolution of the deep atmosphere, and the acceleration of the zonal flow or
jet. We find the occurrence of a super-rotating equatorial jet is robust to
changes in various parameters, and over long timescales, even in the absence of
strong inner or bottom boundary drag. This jet is diminished in one simulation
only, where we strongly force the deep atmosphere equator-to-pole temperature
gradient over long timescales. Finally, although the eddy momentum fluxes in
our atmosphere show similarities with the proposed mechanism for accelerating
jets on tidally-locked planets, the picture appears more complex. We present
tentative evidence for a jet driven by a combination of eddy momentum transport
and mean flow.Comment: 26 pages, 22 Figures. Accepted for publication in Astronomy and
Astrophysic
Natural resources of Lake Earl and Smith River Delta
The Lake Earl/Smith River Delta area is a key coastal wetland situated in northern California. The Lake and Delta have retained much of their value to wildlife and serve as an important link in a chain of such wetlands that extend southward along the Pacific Ocean from Alaska to South America. Millions of water-associated birds of the Pacific Flyway utilize these areas as feeding and resting stops along their migration paths. In California, these wetlands also serve as a significant portion of the available wintering grounds for a major share of the birds within the flyway.
The Smith River is also one of the State's most productive salmon and steelhead streams. Anadromous fish produced here provide thousands of angler use days to sport fishermen and contribute substantially to the commercial fishing catch off the northern coast.
Because of the importance of coastal wetlands to the fish and wildlife of California, the Department of Fish and Game has initiated a high priority statewide inventory and assessment of these wetlands. This publication is an integral part of that program.
This report identifies specific resources and uses; directs attention to problems; and recommends courses of action needed to insure resource protection. It is intended as a guide for citizens, planners, administrators and other
interested in the use and development of California's
coastal land and waters. (132pp.
Accurate and efficient target prediction using a potency-sensitive influence-relevance voter
BACKGROUND: A number of algorithms have been proposed to predict the biological targets of diverse molecules. Some are structure-based, but the most common are ligand-based and use chemical fingerprints and the notion of chemical similarity. These methods tend to be computationally faster than others, making them particularly attractive tools as the amount of available data grows. RESULTS: Using a ChEMBL-derived database covering 490,760 molecule-protein interactions and 3236 protein targets, we conduct a large-scale assessment of the performance of several target-prediction algorithms at predicting drug-target activity. We assess algorithm performance using three validation procedures: standard tenfold cross-validation, tenfold cross-validation in a simulated screen that includes random inactive molecules, and validation on an external test set composed of molecules not present in our database. CONCLUSIONS: We present two improvements over current practice. First, using a modified version of the influence-relevance voter (IRV), we show that using molecule potency data can improve target prediction. Second, we demonstrate that random inactive molecules added during training can boost the accuracy of several algorithms in realistic target-prediction experiments. Our potency-sensitive version of the IRV (PS-IRV) obtains the best results on large test sets in most of the experiments. Models and software are publicly accessible through the chemoinformatics portal at http://chemdb.ics.uci.edu/ ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13321-015-0110-6) contains supplementary material, which is available to authorized users
Simulation of a Rising Sun Magnetron Employing a Faceted Cathode with a Continuous Current Source
It has been proposed that gated field emitters could be used in place of conventional thermionic cathodes to control the current injection in a magnetron, both temporally and spatially. Since gated field emitters have to be fabricated on flat surfaces, a faceted cathode would be used to implement this approach. A 2D ten cavity, rising sun magnetron has been modeled using the particle-in-cell code VORPAL. Cylindrical, five-sided, and ten-sided faceted cathodes were modeled to study the variation of magnetron operation due to the cathode shape. This work shows the results of the device performance employing three different cathode geometries with a typical continuous current source. The cathode voltage is −22.2 kV; magnetic field is 0.09 T; and linear current density is 326 A/m. The three models oscillated at the π-mode, at a frequency of 960 MHz for the cylindrical cathode and 957 MHz for the faceted cathodes. Simulations show a faster start up time for the ten-sided faceted cathode. This resulted in a reduced overall startup time of the device from 200 to 110 ns. A strong current instability was observed in the five-sidedcathode case with a periodicity range from 250 to 350 ns. This instability was limited to the start-up period of the ten-sided cathode model; hence the ten-sided case was more stable
Turbulent Convection in Stellar Interiors. II. The Velocity Field
We analyze stellar convection with the aid of 3D hydrodynamic simulations,
introducing the turbulent cascade into our theoretical analysis. We devise
closures of the Reynolds-decomposed mean field equations by simple physical
modeling of the simulations (we relate temperature and density fluctuations via
coefficients); the procedure (CABS, Convection Algorithms Based on Simulations)
is terrestrially testable and is amenable to systematic improvement. We develop
a turbulent kinetic energy equation which contains both nonlocal and time
dependent terms, and is appropriate if the convective transit time is shorter
than the evolutionary time scale. The interpretation of mixing-length theory
(MLT) as generally used in astrophysics is incorrect; MLT forces the mixing
length to be an imposed constant. Direct tests show that the damping associated
with the flow is that suggested by Kolmogorov. The eddy size is approximately
the depth of the convection zone, and this dissipation length corresponds to
the "mixing length". New terms involving local heating by turbulent dissipation
should appear in the stellar evolution equations. The enthalpy flux
("convective luminosity") is directly connected to the buoyant acceleration,
and hence the velocity scale. MLT tends to systematically underestimate this
velocity scale. Quantitative comparison with a variety of 3D simulations
reveals a previously recognized consistency. Examples of application to stellar
evolution will be presented in subsequent papers in this series.Comment: 47 pages, 7 figures, accepted by Ap
Produit eul\'erien motivique et courbes rationnelles sur les vari\'et\'es toriques
We study the asymptotical behaviour of the moduli space of morphisms of given
anticanonical degree from a rational curve to a split toric variety, when the
degree goes to infinity. We obtain in this case a geometric analogue of Manin's
conjecture about rational points of bounded height on varieties defined over a
global field. The study is led through a generating series whose coefficients
lie in a Grothendieck ring of motives, the motivic height zeta function. In
order to establish convergence properties of this function, we use a notion of
eulerian motivic product. It relies on a construction of Denef and Loeser which
associates a virtual motive to a first order logic ring formula
Dynamic Phase-Control of a Rising Sun Magnetron Using Modulated and Continuous Current
Phase-control of a magnetron is studied via simulation using a combination of a continuous current source and a modulated current source. The addressable, modulated current source is turned ON and OFF at the magnetron operating frequency in order to control the electron injection and the spoke phase. Prior simulation work using a 2D model of a Rising Sun magnetron showed that the use of 100% modulated current controlled the magnetron phase and allowed for dynamic phase control. In this work, the minimum fraction of modulated current source needed to achieve a phase control is studied. The current fractions (modulated versus continuous) were varied from 10% modulated current to 100% modulated current to study the effects on phase control. Dynamic phase-control, stability, and start up time of the device were studied for all these cases showing that with 10% modulated current and 90% continuous current, a phase shift of 180˚ can be achieved demonstrating dynamic phase control
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