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Articles 1021 - 1050 of 1876
Full-Text Articles in Physical Sciences and Mathematics
First Observation Of The Very Rare Decay Neutral Kaon(Long) Going To Electron Positron, Robert David Martin Iii
First Observation Of The Very Rare Decay Neutral Kaon(Long) Going To Electron Positron, Robert David Martin Iii
Dissertations, Theses, and Masters Projects
Brookhaven National Laboratory AGS Experiment 871 (E871) has carried out a search for the very rare, GIM and helicity suppressed decay of the long-lived neutral kaon into an electron-positron pair. This decay is predicted within the Standard Model to occur with a branching ratio of {dollar}(9.0 \pm 0.4)\times 10\sp{lcub}-12{rcub}.{dollar} Data were taken during the 1995 and 1996 AGS HEP running periods on the B5 beamline. A signal of (4 {dollar}\pm{dollar} 2) {dollar}K\sbsp{lcub}L{rcub}{lcub}0{rcub} \to e\sp+e\sp-{dollar} events is seen with a physics background expectation of 0.2 events. The ratio of the partial decay widths {dollar}\Gamma(K\sbsp{lcub}L{rcub}{lcub}0{rcub} \to e\sp+e\sp-)/\Gamma(K\sbsp{lcub}L{rcub}{lcub}0{rcub}\to\mu\sp+\mu\sp-){dollar} is determined to be {dollar}(1.3\sbsp{lcub}-0.6{rcub}{lcub}+0.8{rcub} …
Analysis Of Algorithms For Online Routing And Scheduling In Networks, Jessen Tait Havill
Analysis Of Algorithms For Online Routing And Scheduling In Networks, Jessen Tait Havill
Dissertations, Theses, and Masters Projects
We study situations in which an algorithm must make decisions about how to best route and schedule data transfer requests in a communication network before each transfer leaves its source. For some situations, such as those requiring quality of service guarantees, this is essential. For other situations, doing work in advance can simplify decisions in transit and increase the speed of the network. In order to reflect realistic scenarios, we require that our algorithms be online, or make their decisions without knowing future requests. We measure the efficiency of an online algorithm by its competitive ratio, which is the maximum …
Improvements To The Color Quantization Process, Rance David Necaise
Improvements To The Color Quantization Process, Rance David Necaise
Dissertations, Theses, and Masters Projects
The presentation of color images on devices with limited color capabilities requires a reduction in the number of colors contained in the images. Color image quantization is the process of reducing the number of colors used in an image while maintaining its appearance as much as possible. This reduction is performed using a color image quantization algorithm. The quantization algorithm attempts to select k colors that best represent the contents of the image. The original image is then recolored using the representative colors. to improve the resulting image, a dithering process can be used in place of the recoloring.;This dissertation …
Stability Of Quark-Antiquark Models Of Mesons: A Study On The Validity Of The Spectator, Dirac, And Salpeter Equations, Michael Uzzo
Stability Of Quark-Antiquark Models Of Mesons: A Study On The Validity Of The Spectator, Dirac, And Salpeter Equations, Michael Uzzo
Dissertations, Theses, and Masters Projects
Mesons are made of quark-antiquark pairs held together by the strong force. The one channel spectator, Dirac, and Salpeter equations can each be used to model this pairing. We look at cases where the relativistic kernel of these equations corresponds to a linear combination of scalar exchange and vector exchange. The vector exchange will be either the time-like component or the full four vector. The systems covered here are referred to as quasirelativistic, which means retardation, regularization, and form factors are not included. Since the model used in this paper describes mesons which cannot decay physically, the equations must describe …
Tidal Freshwater And Oligohaline Benthos: Evaluating The Development Of A Benthic Index Of Biological Integrity For Chesapeake Bay, Robyn C. Draheim
Tidal Freshwater And Oligohaline Benthos: Evaluating The Development Of A Benthic Index Of Biological Integrity For Chesapeake Bay, Robyn C. Draheim
Dissertations, Theses, and Masters Projects
No abstract provided.
Processes Affecting Macroalgal-Seagrass Dynamics In The York River, Virginia, Eva Machelor Bailey
Processes Affecting Macroalgal-Seagrass Dynamics In The York River, Virginia, Eva Machelor Bailey
Dissertations, Theses, and Masters Projects
No abstract provided.
The Parasite Fauna Of The Wreckfish, Polyprion Americanus, In The North Atlantic Ocean: Application To Host Biology And Stock Identification, Colleen Jill Fennessy
The Parasite Fauna Of The Wreckfish, Polyprion Americanus, In The North Atlantic Ocean: Application To Host Biology And Stock Identification, Colleen Jill Fennessy
Dissertations, Theses, and Masters Projects
No abstract provided.
Vertebral Cartilage Of The Clearnose Skate, Raja Eglanteria: Development, Structure, Ageing, And Hormonal Regulation Of Growth, James J. Gelsleichter
Vertebral Cartilage Of The Clearnose Skate, Raja Eglanteria: Development, Structure, Ageing, And Hormonal Regulation Of Growth, James J. Gelsleichter
Dissertations, Theses, and Masters Projects
Incremental marks formed in the vertebral cartilage of most sharks, skates and rays are widely used as indicators of age in elasmobranch growth studies. Such information is essential for fisheries management, thus vertebral ageing has become an invaluable tool for investigating elasmobranch life history. Unfortunately, lack of information on the processes that regulate vertebral growth and mineralization limit efforts to correlate episodic stimuli with increment production. to address this research need, this dissertation investigated these processes through a detailed study on the vertebral cartilage of the clearnose skate, Raja eglanteria. Histologic observations indicated that changes in appositional cartilage growth are …
Caribbean Spiny Lobster And Their Molluscan Prey: Are Top-Down Forces Key In Structuring Prey Assemblages In A Florida Bay Seagrass System, Martha Nizinski
Caribbean Spiny Lobster And Their Molluscan Prey: Are Top-Down Forces Key In Structuring Prey Assemblages In A Florida Bay Seagrass System, Martha Nizinski
Dissertations, Theses, and Masters Projects
Relative importance of predator-prey dynamics and several environmental variables in structuring gastropod and bivalve diversity and distribution was investigated in the subtropical seagrass and macroalgal community of Florida Bay, a highly productive system and primary nursery and foraging ground for finfish and invertebrate predators, including the numerically dominant Caribbean spiny lobster, Panulirus argus. The molluscan assemblage, a primary food source for P. argus in particular, is speciose (75 gastropod and 25 bivalve species) and a significant component of epifaunal and infaunal invertebrate assemblages within Florida Bay. Two experimental areas, located within separate basins and each comprised of two experimental sites, …
Physical Parameters Affecting Incubating Temperatures In Loggerhead Sea Turtles, Caretta Caretta, In Virginia, William Mason Jones
Physical Parameters Affecting Incubating Temperatures In Loggerhead Sea Turtles, Caretta Caretta, In Virginia, William Mason Jones
Dissertations, Theses, and Masters Projects
Detailed physical profile of eight transplanted loggerhead sea turtle, Caretta caretta, nests were obtained from Virginia and northeastern North Carolina and reburied in Back Bay National Wildlife Refuge (BBNWR), Virginia Beach, Virginia during the summers of 1987, '88, and '89 to determine if the physical location of the egg within the nest had an affect on sex determination. Transplanted nests were reburied in sandy substrate at a depth of 15-60 em on south facing dunes, and a Campbell Scientific data-logger logged synchronously environmental data. The following data were collected: temperatures at various locations within a nest, net absorbed radiation, ambient …
Oyster Reef Broodstock Enhancement In The Great Wicomico River, Virginia, Melissa Southworth
Oyster Reef Broodstock Enhancement In The Great Wicomico River, Virginia, Melissa Southworth
Dissertations, Theses, and Masters Projects
No abstract provided.
Wind Interaction With Buoyant Plumes On The Inner Continental Shelf, Sarah E. Rennie
Wind Interaction With Buoyant Plumes On The Inner Continental Shelf, Sarah E. Rennie
Dissertations, Theses, and Masters Projects
The characteristics and effects of intrusions of estuarine outflow over the inner shelf were examined, based on hydrographic and meteorological observations obtained during the "Coastal Ocean Processes" (CoOP'94) field experiment located off the Outer Banks at Duck, North Carolina. The episodic presence of distinct low salinity water masses issuing from the Chesapeake Bay created an intermittent baroclinic coastal current along the North Carolina coast. Under low wind conditions, this current occupied the upper half of the water column within 9 km of the coast. The plume was bounded by a distinct southward-propagating front, a region offshore of high horizontal salinity …
Ecosystem Analysis Of Water Column Processes In The York River Estuary, Virginia: Historical Records, Field Studies And Modeling Analysis, Yongsik Sin
Dissertations, Theses, and Masters Projects
Analyses of EPA long-term datasets (1985--1994) combined with field studies and ecosystem model development were used to investigate phytoplankton and nutrient dynamics in the York River estuary. Analysis of the EPA dataset showed that algal blooms occurred during winter-spring followed by smaller summer blooms. Peak phytoplankton biomass during the winter-spring blooms occurred in the mid reach of the mesohaline zone whereas during the summer bloom it occurred in the tidal fresh-mesolialine transition zone. River discharge appears to be the major factor controlling the location and timing of the winter-spring blooms and the relative degree of potential nitrogen (N) and phosphorus …
A Probability Programming Language: Development And Applications, Andrew Gordon Glen
A Probability Programming Language: Development And Applications, Andrew Gordon Glen
Dissertations, Theses, and Masters Projects
A probability programming language is developed and presented; applications illustrate its use. Algorithms and generalized theorems used in probability are encapsulated into a programming environment with the computer algebra system Maple to provide the applied community with automated probability capabilities. Algorithms of procedures are presented and explained, including detailed presentations on three of the most significant procedures. Applications that encompass a wide range of applied topics including goodness-of-fit testing, probabilistic modeling, central limit theorem augmentation, generation of mathematical resources, and estimation are presented.
A Search For Lepton Flavor Violation In The Neutral Kaon System, Christopher Henry Hoff
A Search For Lepton Flavor Violation In The Neutral Kaon System, Christopher Henry Hoff
Dissertations, Theses, and Masters Projects
The conservation of separate lepton number is an ad hoc conservation principle in the Standard Model but several non-Standard Model theories allow violation of separate lepton number conservation. A very sensitive search for lepton flavor violation in the neutral kaon system, via the decay K0L→me , was undertaken by Brookhaven National Laboratory Experiment 871 (E871) during the 1995 and 1996 AGS HEP running periods. No K0L→me decays were observed and a single event sensitivity (SES) of 1.97x10-12 was achieved. This single event sensitivity corresponds to an upper limit on the branching fraction of BK0L→m e<4.53+/-0.21+/-0.46x 10-12 at a 90% confidence level.
Coherent Neutral Pion Photoproduction On The Deuteron, David G. Meekins
Coherent Neutral Pion Photoproduction On The Deuteron, David G. Meekins
Dissertations, Theses, and Masters Projects
The differential scattering cross section for the process gd→dp0 was measured, as part of experiment E89-012 at Thomas Jefferson National Accelerator Facility. The experiment was performed in Hall C during the Spring of 1996 as the commissioning experiment for the Hall C cryogenic target. The High Momentum Spectrometer was used to detect the recoil deuteron and no effort was made to detect the p0 or its decay photons. The differential cross section was measured at a number of incident photon energies between 0.8 GeV and 4.0 GeV for the deuteron center-of-mass angles of 90?? and 136??. The data were found …
Wavelet-Based Digital Image Restoration, Viviana Sandor
Wavelet-Based Digital Image Restoration, Viviana Sandor
Dissertations, Theses, and Masters Projects
Digital image restoration is a fundamental image processing problem with underlying physical motivations. A digital imaging system is unable to generate a continuum of ideal pointwise measurements of the input scene. Instead, the acquired digital image is an array of measured values. Generally, algorithms can be developed to remove a significant part of the error associated with these measure image values provided a proper model of the image acquisition system is used as the basis for the algorithm development. The continuous/discrete/continuous (C/D/C) model has proven to be a better alternative compared to the relatively incomplete image acquisition models commonly used …
The Role Of Adsorbed Oxygen In Secondary Emission From Metallic Substrates, Scott Gregory Walton
The Role Of Adsorbed Oxygen In Secondary Emission From Metallic Substrates, Scott Gregory Walton
Dissertations, Theses, and Masters Projects
Low energy, ion- and photon-induced secondary electron and anion emission from metallic substrates has been investigated as a function of adsorbate coverage. Sodium positive ions (Na+), with kinetic energies up to 500 eV, and photons, with energies up to 23 eV, are utilized to initiate secondary emission. The principal adsorbate is oxygen with coverages ranging from none to a few monolayers.;For ion-induced emission, the secondary electron and negative ion absolute and relative yields from 302 stainless steel and polycrystalline tungsten (W) have been measured as a function of both impact energy and oxygen coverage. Additionally, the yields from a "technical" …
Comparative Evolution Of Molecular Markers: An Analysis Of Genetic Variation Within The Blue Marlin (Makaira Nigricans), Vincent Patrick Buonaccorsi
Comparative Evolution Of Molecular Markers: An Analysis Of Genetic Variation Within The Blue Marlin (Makaira Nigricans), Vincent Patrick Buonaccorsi
Dissertations, Theses, and Masters Projects
Blue marlin diversity was assessed at mtDNA, scnDNA, microsatellite DNA, and allozyme molecular markers. Hierarchical analysis of molecular variance (AMOVA) revealed that most genetic variation was maintained within populations, with a non-significant fraction attributable to variation among temporal replicates and between locations within oceans. In contrast, inter-ocean divergence was highly significant for a majority of loci within each marker class. Previous studies of mitochondrial DNA (mtDNA; n = 104) genetic variation within the blue marlin revealed two distinct clades of haplotypes, one of which was present only in the Atlantic (the 'Atlantic clade'), at a frequency of 40% &(F\sb{lcub}st{rcub}& = …
Electroproduction Of The S(11)Meson(1535) Resonance At High Momentum Transfer, Christopher Stephen Armstrong
Electroproduction Of The S(11)Meson(1535) Resonance At High Momentum Transfer, Christopher Stephen Armstrong
Dissertations, Theses, and Masters Projects
The amplitude of the $S\sb{11}$(1535) resonance at values of four-momentum transfer $Q\sp2 > 0$ is not explained by the nonrelativistic constituent quark model, and is currently a topic of theoretical interest; in addition, the large branching fraction of this resonance to the proton-$\eta$ decay channel is not well understood. There is also controversy concerning the $Q\sp2$ regime in which perturbative QCD becomes important in describing nucleon resonances such as the $S\sb{11}$. The $p(e, e\sp\prime p)\eta$ reaction is an excellent system in which to study this resonance and address the issue of possible perturbative effects: the $p\eta$ channel is not accessible to …
Exploiting Cache Locality At Run-Time, Yong Yan
Exploiting Cache Locality At Run-Time, Yong Yan
Dissertations, Theses, and Masters Projects
With the increasing gap between the speeds of the processor and memory system, memory access has become a major performance bottleneck in modern computer systems. Recently, Symmetric Multi-Processor (SMP) systems have emerged as a major class of high-performance platforms. Improving the memory performance of Parallel applications with dynamic memory-access patterns on Symmetric Multi-Processors (SMP) is a hard problem. The solution to this problem is critical to the successful use of the SMP systems because dynamic memory-access patterns occur in many real-world applications. This dissertation is aimed at solving this problem.;Based on a rigorous analysis of cache-locality optimization, we propose a …
Platinized Tin Oxide: A Low-Temperature Oxidation Catalyst, Erik Joshua Kielin
Platinized Tin Oxide: A Low-Temperature Oxidation Catalyst, Erik Joshua Kielin
Dissertations, Theses, and Masters Projects
Some combinations of noble metal and reducible metal oxide possess a synergistic level of activity for the catalytic oxidation of CO at lower temperatures and partial pressures of O2 than can be obtained by either component alone. The most promising candidates, Au on MnO2 and Pt on SnO 2, were investigated for the effects on activity of noble metal loading, of reductive pretreatment at elevated temperature, and of reaction gas mixture composition. Optimum activity was obtained at a noble metal loading of 28% Au/MnO2 and 17% Pt/SnO2. Both catalysts benefitted from reductive CO pretreatment at 125??C. Both catalysts showed enhanced …
The Selective Oxidation Of Beta-Cyclodextrin On The Secondary Face, Christine Evelyn Heath
The Selective Oxidation Of Beta-Cyclodextrin On The Secondary Face, Christine Evelyn Heath
Dissertations, Theses, and Masters Projects
No abstract provided.
Analysis Of Mercury Coordination Environments Of Tridentate And Tetradentate Nitrogen Based Ligands By Nmr Spectroscopy And X-Ray Crystallography, Rachel E. Freer
Analysis Of Mercury Coordination Environments Of Tridentate And Tetradentate Nitrogen Based Ligands By Nmr Spectroscopy And X-Ray Crystallography, Rachel E. Freer
Dissertations, Theses, and Masters Projects
No abstract provided.
Polycyclic Aromatic Hydrocarbon (Pah) Distributions Within Urban Estuarine Sediments, Siddhartha Mitra
Polycyclic Aromatic Hydrocarbon (Pah) Distributions Within Urban Estuarine Sediments, Siddhartha Mitra
Dissertations, Theses, and Masters Projects
Sediments and pore waters from two urban estuaries ranging in sediment mixing energy were studied to evaluate the potential release of contaminants from particles during sediment diagenesis. Two sites in Elizabeth River, VA and two tributaries in the Hudson River Watershed were sampled for polycyclic aromatic hydrocarbons (PAHs). Sediment age, total sediment organic carbon (TOC), carbon to nitrogen (C/N) ratios, and particle surface area (SA) were also sampled at these sites. In the Elizabeth River, both sites sampled (Site 1 and Site 2) have been non-depositional for the past 70 y or are comprised of old dredge spoil. PAH K&\sp\prime\sb{lcub}\rm …
Small Mammal Habitat Uses Of Two Natural And Created Wetlands In Southeastern Virginia, Amanda Mckenney Mueller
Small Mammal Habitat Uses Of Two Natural And Created Wetlands In Southeastern Virginia, Amanda Mckenney Mueller
Dissertations, Theses, and Masters Projects
No abstract provided.
Distribution Of Freshwater Amphipoda In The Lake Matoaka/College Woods Area, Williamsburg, Virginia, Susan Alexandra Mahon
Distribution Of Freshwater Amphipoda In The Lake Matoaka/College Woods Area, Williamsburg, Virginia, Susan Alexandra Mahon
Dissertations, Theses, and Masters Projects
No abstract provided.
The Influence Of Microstructure On The Thermal Degradation Behavior Of Poly(Vinyl Chloride), Hoang Vi Tran
The Influence Of Microstructure On The Thermal Degradation Behavior Of Poly(Vinyl Chloride), Hoang Vi Tran
Dissertations, Theses, and Masters Projects
No abstract provided.
Correspondence Between Environmental Gradients And The Assemblage Structure Of Littoral Fishes In The Tidal Portion Of Three Virginia Coastal Plain Rivers, Clifford Michael Wagner
Correspondence Between Environmental Gradients And The Assemblage Structure Of Littoral Fishes In The Tidal Portion Of Three Virginia Coastal Plain Rivers, Clifford Michael Wagner
Dissertations, Theses, and Masters Projects
No abstract provided.
The Synthesis Of 6a,6b-Dideoxy-6 A,6b-(9,10-Dicyanoanthracenyl-2,3-Dimethylene)-Beta-Cyclodextrin, Jonathan D. Tan
The Synthesis Of 6a,6b-Dideoxy-6 A,6b-(9,10-Dicyanoanthracenyl-2,3-Dimethylene)-Beta-Cyclodextrin, Jonathan D. Tan
Dissertations, Theses, and Masters Projects
No abstract provided.