3,907 research outputs found

    Quality and price of fresh market strawberries in West Tennessee

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    Tennessee strawberry producers have received an average of about three and one-half million dollars annually from strawberry sales for the past ten years. While this amount is less than one percent of the state\u27s total crop value, strawberries rank eighth as a source of crop income. In addition to being the most widely grown truck crop, they have been in most years the most valuable crop. Unlike most other crops, the characteristics of the strawberry make the marketing process extremely difficult. The product grade or quality as established on the farm never improves during the product\u27s journey to the consumer. Deterioration sets in immediately after harvest, many times before, and continues at a rate determined by environmental conditions. The primary environmental factors of temperature and humidity are not always easily controlled in the marketing process, as evidenced by present marketing techniques. It is, therefore, very important that as strawberries start through the marketing channels that they have the proper quality characteristics if they are to make this market journey successfully. Many factors Influencing quality on the farm cannot be controlled but harvesting methods can directly influence the product grade. While quality receives much credit for the success of a marketing season, the medium of awarding such success is through price. Costa and returns are the final guage for the grower in measuring the success of a particular enterprise. The quality of a product is expected to respond to price incentive and price is expected to rise or fall with quality where quality is the main consideration in establishing price. Quality is supposed to provide a basis for establishing value at the various levels of marketing and is especially important in determining first sale price of some farm products. The grade or degree of quality is described by industry-wide standards and the respondent price is supposedly determined by product demand and supply the translation of these forces by local marketing firms. Yet, it may be that impediments arise which so reduce the level of interplay between these forces that proper responses are not seen in certain markets. The farmer and the marketing firm are both strongly concerned with price and quality factors

    Evaporite karst geohazards in the Delaware Basin, Texas: review of traditional karst studies coupled with geophysical and remote sensing characterization

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    Evaporite karst throughout the Gypsum Plain of west Texas is complex and extensive, including manifestations ranging from intrastratal brecciation and hypogene caves to epigene features and suffosion caves. Recent advances in hydrocarbon exploration and extraction has resulted in increased infrastructure development and utilization in the area; as a result, delineation and characterization of potential karst geohazards throughout the region have become a greater concern. While traditional karst surveys are essential for delineating the subsurface extent and morphology of individual caves for speleogenetic interpretation, these methods tend to underestimate the total extent of karst development and require surficial manifestation of karst phenomena. Therefore, this study utilizes a composite suite of remote sensing and traditional field studies for improved karst delineation and detection of potential karst geohazards within gypsum karst. Color InfraRed (CIR) imagery were utilized for delineation of lineaments associated with fractures, while Normalized Density Vegetation Index (NDVI) analyses were used to delineate regions of increased moisture flux and probable zones of shallow karst development. Digital Elevation Models (DEM) constructed from high-resolution LiDAR (Light Detection and Ranging) data were used to spatially interpret sinkholes, while analyses of LiDAR intensity data were used in a novel way to categorize local variations in surface geology. Resistivity data, including both direct current (DC) and capacitively coupled (CC) resistivity analyses, were acquired and interpreted throughout the study area to delineate potential shallow karst geohazards specifically associated with roadways of geohazard concern; however, detailed knowledge of the surrounding geology and local karst development proved essential for proper interpretation of resistivity inversions. The composite suite of traditional field investigations and remotely sensed karst delineations used in this study illustrate how complex gypsum karst terrains can be characterized with greater detail through the utilization of rapidly advancing technologies, especially in arid environments with low vegetation densities

    Fields of accelerated sources: Born in de Sitter

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    This paper deals thoroughly with the scalar and electromagnetic fields of uniformly accelerated charges in de Sitter spacetime. It gives details and makes various extensions of our Physical Review Letter from 2002. The basic properties of the classical Born solutions representing two uniformly accelerated charges in flat spacetime are first summarized. The worldlines of uniformly accelerated particles in de Sitter universe are defined and described in a number of coordinate frames, some of them being of cosmological significance, the other are tied naturally to the particles. The scalar and electromagnetic fields due to the accelerated charges are constructed by using conformal relations between Minkowski and de Sitter space. The properties of the generalized `cosmological' Born solutions are analyzed and elucidated in various coordinate systems. In particular, a limiting procedure is demonstrated which brings the cosmological Born fields in de Sitter space back to the classical Born solutions in Minkowski space. In an extensive Appendix, which can be used independently of the main text, nine families of coordinate systems in de Sitter spacetime are described analytically and illustrated graphically in a number of conformal diagrams.Comment: 37 pages, 23 figures, reformatted version of the paper published in JMP; low-resolution figures due to arXiv size restrictions; for the version with high-resolution figures see http://utf.mff.cuni.cz/~krtous/papers

    General plane wave mode functions for scalar-driven cosmology

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    We give a solution for plane wave scalar, vector and tensor mode functions in the presence of any homogeneous, isotropic and spatially flat cosmology which is driven by a single, minimally coupled scalar. The solution is obtained by rescaling the various mode functions so that they reduce, with a suitable scale factor and a suitable time variable, to those of a massless, minimally coupled scalar. We then express the general solution in terms of co-moving time and the original scale factor.Comment: 6 pages, revtex4, no figures, revised version corrects an embarrassing mistake (in the published version) for the parameter q_C. Affected eqns are 45 and 6

    A graviton propagator for inflation

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    We construct the scalar and graviton propagator in quasi de Sitter space up to first order in the slow roll parameter ϵH˙/H2\epsilon\equiv -\dot{H}/H^2. After a rescaling, the propagators are similar to those in de Sitter space with an ϵ\epsilon correction to the effective mass. The limit ϵ0\epsilon\to 0 corresponds to the E(3) vacuum that breaks de Sitter symmetry, but does not break spatial isotropy and homogeneity. The new propagators allow for a self-consistent, dynamical study of quantum back-reaction effects during inflation.Comment: 23 page

    The Fermion Self-Energy during Inflation

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    We compute the one loop fermion self-energy for massless Dirac + Einstein in the presence of a locally de Sitter background. We employ dimensional regularization and obtain a fully renormalized result by absorbing all divergences with BPHZ counterterms. An interesting technical aspect of this computation is the need for a noninvariant counterterm owing to the breaking of de Sitter invariance by our gauge condition. Our result can be used in the quantum-corrected Dirac equation to search for inflation-enhanced quantum effects from gravitons, analogous to those which have been found for massless, minimally coupled scalars.Comment: 63 pages, 3 figures (uses axodraw.sty), LaTeX 2epsilon. Revised version (to appear in Classical and Quantum Gravity) corrects some typoes and contains some new reference

    Hilbert Space Structures on the Solution Space of Klein-Gordon Type Evolution Equations

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    We use the theory of pseudo-Hermitian operators to address the problem of the construction and classification of positive-definite invariant inner-products on the space of solutions of a Klein-Gordon type evolution equation. This involves dealing with the peculiarities of formulating a unitary quantum dynamics in a Hilbert space with a time-dependent inner product. We apply our general results to obtain possible Hilbert space structures on the solution space of the equation of motion for a classical simple harmonic oscillator, a free Klein-Gordon equation, and the Wheeler-DeWitt equation for the FRW-massive-real-scalar-field models.Comment: 29 pages, slightly revised version, accepted for publication in Class. Quantum Gra
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