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Search Results: 1 - 10 of 325375 matches for " S. Dye "
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Structure and Growth of the Leeward Kohala Field System: An Analysis with Directed Graphs
Thomas S. Dye
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102431
Abstract: This study illustrates how the theory of directed graphs can be used to investigate the structure and growth of the leeward Kohala field system, a traditional Hawaiian archaeological site that presents an unparalleled opportunity to investigate relative chronology. The relative chronological relationships of agricultural walls and trails in two detailed study areas are represented as directed graphs and then investigated using graph theoretic concepts including cycle, level, and connectedness. The structural properties of the directed graphs reveal structure in the field system at several spatial scales. A process of deduction yields a history of construction in each detailed study area that is different than the history produced by an earlier investigation. These results indicate that it is now possible to study the structure and growth of the entire field system remnant using computer software implementations of graph theoretic concepts applied to observations of agricultural wall and trail intersections made on aerial imagery and/or during fieldwork. A relative chronology of field system development with a resolution of one generation is a possible result.
Neutrino Mixing Discriminates Geo-reactor Models
S. T. Dye
Physics , 2009, DOI: 10.1016/j.physletb.2009.07.010
Abstract: Geo-reactor models suggest the existence of natural nuclear reactors at different deep-earth locations with loosely defined output power. Reactor fission products undergo beta decay with the emission of electron antineutrinos, which routinely escape the earth. Neutrino mixing distorts the energy spectrum of the electron antineutrinos. Characteristics of the distorted spectrum observed at the earth's surface could specify the location of a geo-reactor, discriminating the models and facilitating more precise power measurement. The existence of a geo-reactor with known position could enable a precision measurement of the neutrino oscillation parameter delta-mass-squared.
Self-consistent Gravitational Lens Reconstruction
S. Dye,A. Taylor
Physics , 1998, DOI: 10.1046/j.1365-8711.1998.02056.x
Abstract: We present a new method for directly determining accurate, self-consistent cluster lens mass and shear maps in the strong lensing regime from the magnification bias of background galaxies. The method relies upon pixellisation of the surface mass density distribution which allows us to write down a simple, solvable set of equations. We also show how pixellisation can be applied to methods of mass determination from measurements of shear and present a simplified method of application. The method is demonstrated with cluster models and applied to magnification data from the lensing cluster Abell 1689.
S. T. Dye
Physics , 2008, DOI: 10.1016/j.nuclphysbps.2009.02.032
Abstract: This paper briefly reviews recent developments in the field of geo-neutrinos. It describes current and future detection projects, discusses modeling projects, suggests an observational program, and visits geo-reactor hypotheses.
Eucalyptus and Water Use in South Africa
Janine M. Albaugh,Peter J. Dye,John S. King
International Journal of Forestry Research , 2013, DOI: 10.1155/2013/852540
Eucalyptus and Water Use in South Africa
Janine M. Albaugh,Peter J. Dye,John S. King
International Journal of Forestry Research , 2013, DOI: 10.1155/2013/852540
Abstract: The Eucalyptus genus yields high rates of productivity and can be grown across a wide range of site types and climates for products such as pulp, fuelwood, or construction lumber. In addition, many eucalypts have the ability to coppice, making this genus an ideal candidate for use as a biofuel feedstock. However, the water use of Eucalyptus is a controversial issue, and the impacts of these fast-growing trees on water resources are well documented. Regardless, the demand for wood products and water continues to rise, providing a challenge to increase the productivity of forest plantations within water constraints. This is of particular relevance for water-limited countries such as South Africa which relies on exotic plantations to meet its timber needs. Research results from water use studies in South Africa are well documented and legislation restrictions limit further afforestation. This paper outlines techniques used to quantify the water use of eucalypt plantations and provides recommendations on where to focus future research efforts. Greater insights into the water use efficiency of clonal material are needed, as certain eucalypt clones show fast growth and low water use. To better understand water use efficiency, estimates should be combined with monitoring of stand canopy structure and measurements of physiological processes. 1. Introduction Eucalyptus is the most widely planted hardwood genus in the world, covering more than 19 million hectares, with growth rates that routinely exceed 35?m3?ha?1 year?1 [1, 2]. These fast-growing plantations can be grown under a range of different climates for products that include pulp and paper, charcoal, fuelwood, and solid wood products such as poles, furniture, and timber construction. Given their fast growth rates and coppicing ability, eucalypts have also been identified as potential feedstocks for lignocellulosic biofuels. Being endemic to Australia, southeast Asia, and the Pacific, eucalypts are grown mainly as exotic species. Consequently, there is much concern about their water consumption, from many countries around the world [3–7]. One such country is South Africa, which relies heavily on plantations of exotic forestry species, particularly Eucalyptus, to meet its timber needs. South Africa is a water-limited country with an average annual rainfall of 560?mm year?1, which results in fierce competition for this limited resource [5]. Concerns over the effects of exotic plantations on South African streamflow and catchment water yields led to the establishment of a network of long-term paired catchment
Testing Geological Models with Terrestrial Antineutrino Flux Measurements
Steve Dye
Physics , 2009,
Abstract: Uranium and thorium are the main heat producing elements in the earth. Their quantities and distributions, which specify the flux of detectable antineutrinos generated by the beta decay of their daughter isotopes, remain unmeasured. Geological models of the continental crust and the mantle predict different quantities and distributions of uranium and thorium. Many of these differences are resolvable with precision measurements of the terrestrial antineutrino flux. This precision depends on both statistical and systematic uncertainties. An unavoidable background of antineutrinos from nuclear reactors typically dominates the systematic uncertainty. This report explores in detail the capability of various operating and proposed geo-neutrino detectors for testing geological models.
Science Potential of a Deep Ocean Antineutrino Observatory
Steve Dye
Physics , 2006, DOI: 10.1016/j.nuclphysbps.2007.02.012
Abstract: This paper presents science potential of a deep ocean antineutrino observatory under development at Hawaii. The observatory design allows for relocation from one site to another. Positioning the observatory some 60 km distant from a nuclear reactor complex enables precision measurement of neutrino mixing parameters, leading to a determination of neutrino mass hierarchy. At a mid-Pacific location the observatory measures the flux and ratio of uranium and thorium decay neutrinos from earth's mantle and performs a sensitive search for a hypothetical natural fission reactor in earth's core. A subsequent deployment at another mid-ocean location would test lateral heterogeneity of uranium and thorium in earth's mantle.
Geo-neutrinos and Silicate Earth Enrichment of U and Th
Steve Dye
Physics , 2010, DOI: 10.1016/j.epsl.2010.06.012
Abstract: The terrestrial distribution of U, Th, and K abundances governs the thermal evolution, traces the differentiation, and reflects the bulk composition of the earth. Comparing the bulk earth composition to chondritic meteorites estimates the net amounts of these radiogenic heat-producing elements available for partitioning to the crust, mantle, and core. Core formation enriches the abundances of refractory lithophile elements, including U and Th, in the silicate earth by ~1.5. Global removal of volatile elements potentially increases this enrichment to ~2.8. The K content of the silicate earth follows from the ratio of K to U. Variable enrichment produces a range of possible heat-producing element abundances in the silicate earth. A model assesses the essentially fixed amounts of U, Th, and K in the approximately closed crust reservoir. Subtracting these sequestered crustal amounts from the variable amounts in the silicate earth results in a range of possible mantle allocations, leaving global dynamics and thermal evolution poorly constrained. Terrestrial antineutrinos from {\beta}-emitting daughter nuclei in the U and Th decay series traverse the earth with negligible attenuation. The rate at which large subsurface instruments observe these geo-neutrinos depends on the distribution of U and Th relative to the detector. Geo-neutrino observations with sensitivity to U and Th in the mantle are able to estimate silicate earth enrichment, leading to a more complete understanding of the origin, accretion, differentiation, and thermal history of the planet.
Geo-neutrinos and the Radioactive Power of the Earth
Steve Dye
Physics , 2011, DOI: 10.1029/2012RG000400
Abstract: Chemical and physical Earth models agree little as to the radioactive power of the planet. Each predicts a range of radioactive powers, overlapping slightly with the other at about 24 TW, and together spanning 14-46 TW. Approximately 20 % of this radioactive power (3-8 TW) escapes to space in the form of geo-neutrinos. The remaining 11-38 TW heats the planet with significant geo-dynamical consequences, appearing as the radiogenic component of the 43-49 TW surface heat flow. The non-radiogenic component of the surface heat flow (5-38 TW) is presumably primordial, a legacy of the formation and early evolution of the planet. A constraining measurement of radiogenic heating provides insights to the thermal history of the Earth and potentially discriminates chemical and physical Earth models. Radiogenic heating in the planet primarily springs from unstable nuclides of uranium, thorium, and potassium. The paths to their stable daughter nuclides include nuclear beta decays, producing geo-neutrinos. Large sub-surface detectors efficiently record the energy but not the direction of the infrequent interactions of the highest energy geo-neutrinos, originating only from uranium and thorium. The measured energy spectrum of the interactions estimates the relative amounts of these heat-producing elements, while the intensity estimates planetary radiogenic power. Recent geo-neutrino observations in Japan and Italy find consistent values of radiogenic heating. The combined result mildly excludes the lowest model values of radiogenic heating and, assuming whole mantle convection, identifies primordial heat loss. Future observations have the potential to measure radiogenic heating with better precision, further constraining geological models and the thermal evolution of the Earth.
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