Radiative Corrections to the top quark width

Calculations of radiative corrections to the top quark width are reviewed. QCD effects are discussed for $t-\bar t$ systems produced in $e^+e^-$ annihilation near the energy threshold.}Comment: Karlsruhe Univ. preprint TTP 93-21, 6p., 2 figures not included (Talk presented by M. Je\.zabek at the Workshop on Physics and Experiments at Linear $e^+e^-$ Colliders, Waikoloa, Hawaii, April 1993

Erratum: Progenitor-explosion connection and remnant birth masses for neutrino-driven supernovae of iron-core progenitors (2012, ApJ, 757, 69)

An erroneous interpretation of the hydrodynamical results led to an incorrect determination of the fallback masses in Ugliano et al. (2012), which also (on a smaller level) affects the neutron star masses provided in that paper. This problem was already addressed and corrected in the follow-up works by Ertl et al. (2015) and Sukhbold et al. (2015). Therefore, the reader is advised to use the new data of the latter two publications. In the remaining text of this Erratum we present the differences of the old and new fallback results in detail and explain the origin of the mistake in the original analysis by Ugliano et al. (2012).Comment: 3 pages, 2 figures; submitted to The Astrophysical Journa

Economic Evaluation of Wind Energy as an Alternative to Natural Gas Powered Irrigation

High natural gas prices have agricultural producers searching for alternative energy sources for irrigation. The economic feasibility of electric and hybrid (electric/wind) systems are evaluated as alternatives to natural gas powered irrigation. Texas Panhandle and Southern Kansas farms are assessed with a quarter-mile sprinkler system, three crops, and two pumping lifts. Breakeven points identify the price at which conversion from a natural gas irrigation system to an electric or hybrid system is cost effective. Results indicate electricity is a more feasible energy source for irrigation and policy changes such as net metering are necessary to make hybrid systems viable.electricity, irrigation, natural gas, wind energy, Agribusiness, Community/Rural/Urban Development, Environmental Economics and Policy, Farm Management, International Development, Land Economics/Use, Research and Development/Tech Change/Emerging Technologies, Resource /Energy Economics and Policy, Q12, Q20, Q42,

Economic Analysis of Manure Harvesting Equipment in Feedyards for Dust Control

This study concentrated on one method of dust control which is harvesting manure with equipment. An economic analysis including hourly fixed and operational costs were performed on the following: tractor-pulled box scraper, front-end loader, dump truck, spreader truck, elevating scraper and tractor-pulled end dump. The purpose of this study was to generate cost data for feedyard owners/operators to reference when making manure management and equipment purchasing decisions.manure harvesting equipment, tractor-pulled box scraper, front-end loader, dump truck, spreader truck, tractor-pulled end dump, Agribusiness, Environmental Economics and Policy,

Economic Analysis of a Water Truck for Feedyard Dust Suppression

Dust created in feedyards can adversely affect cattle performance. Dust suppression can be accomplished by moistening pen surfaces with traveling gun(s) sprinklers, solid-set sprinklers, and water trucks. This study specifically addresses the fixed and operational costs associated with a water truck for various sized feedyards.water truck, dust suppression, fixed costs, operational costs, Farm Management, Livestock Production/Industries,

ECONOMIC FEASIBILITY OF PRECISION IRRIGATION IN THE NORTHERN TEXAS HIGH PLAINS

The benefit of changing to Variable Rate Irrigation (VRI) from uniform application methods needs to be assessed for technology adoption. Precision irrigation involves water application in optimum amounts. Results indicate that feasibility of precision irrigation depends on field variability, crop value, economies of scale, and useful life of the equipment.Land Economics/Use,

Core-Collapse Supernovae: Reflections and Directions

Core-collapse supernovae are among the most fascinating phenomena in astrophysics and provide a formidable challenge for theoretical investigation. They mark the spectacular end of the lives of massive stars and, in an explosive eruption, release as much energy as the sun produces during its whole life. A better understanding of the astrophysical role of supernovae as birth sites of neutron stars, black holes, and heavy chemical elements, and more reliable predictions of the observable signals from stellar death events are tightly linked to the solution of the long-standing puzzle how collapsing stars achieve to explode. In this article our current knowledge of the processes that contribute to the success of the explosion mechanism are concisely reviewed. After a short overview of the sequence of stages of stellar core-collapse events, the general properties of the progenitor-dependent neutrino emission will be briefly described. Applying sophisticated neutrino transport in axisymmetric (2D) simulations with general relativity as well as in simulations with an approximate treatment of relativistic effects, we could find successful neutrino-driven explosions for a growing set of progenitor stars. First results of three-dimensional (3D) models have been obtained, and magnetohydrodynamic simulations demonstrate that strong initial magnetic fields in the pre-collapse core can foster the onset of neutrino-powered supernova explosions even in nonrotating stars. These results are discussed in the context of the present controversy about the value of 2D simulations for exploring the supernova mechanism in realistic 3D environments, and they are interpreted against the background of the current disagreement on the question whether the standing accretion shock instability (SASI) or neutrino-driven convection is the crucial agency that supports the onset of the explosion.Comment: 36 pages, 20 figures (43 eps files); submitted to Progress of Theoretical and Experimental Physics (PTEP

Supernova explosions and the birth of neutron stars

We report here on recent progress in understanding the birth conditions of neutron stars and the way how supernovae explode. More sophisticated numerical models have led to the discovery of new phenomena in the supernova core, for example a generic hydrodynamic instability of the stagnant supernova shock against low-mode nonradial deformation and the excitation of gravity-wave activity in the surface and core of the nascent neutron star. Both can have supportive or decisive influence on the inauguration of the explosion, the former by improving the conditions for energy deposition by neutrino heating in the postshock gas, the latter by supplying the developing blast with a flux of acoustic power that adds to the energy transfer by neutrinos. While recent two-dimensional models suggest that the neutrino-driven mechanism may be viable for stars from about 8 solar masses to at least 15 solar masses, acoustic energy input has been advocated as an alternative if neutrino heating fails. Magnetohydrodynamic effects constitute another way to trigger explosions in connection with the collapse of sufficiently rapidly rotating stellar cores, perhaps linked to the birth of magnetars. The global explosion asymmetries seen in the recent simulations offer an explanation of even the highest measured kick velocities of young neutron stars.Comment: 10 pages, 8 figures, 19 ps files; to be published in Proc. of Conf. "40 Years of Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007, McGill Univ., Montreal, Canada; high-resolution images can be obtained upon request; incorrect panel in fig.8 replace

Cost Analysis and Water Conservation Potential of Irrigation Technologies in the Texas Panhandle Water Planning Area

Six irrigation systems are analyzed considering cost and potential water savings. The investment cost of furrow and drip is $115,800 and$260,120, respectively. The cost of quarter mile pivot ranges from $59,000 to$64,000. Per ac-in variable pumping cost ranges $9.96 to$14.86 assuming natural gas price $7.00 per MCF.Irrigation Technology, Ground Water Planning, Texas Panhandle, Water Conservation, Ogallala, Agribusiness, Environmental Economics and Policy, Farm Management, Production Economics, Resource /Energy Economics and Policy,