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University of Massachusetts Amherst

Masters Theses 1911 - February 2014

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Full-Text Articles in Physical Sciences and Mathematics

Exploring Isotopic Signatures Of Lake El'gygytgyn Sediments For Evidence Of Anoxia And Methane Cycling Over The Past 50,000 Years, Addie R. Holland Jan 2010

Exploring Isotopic Signatures Of Lake El'gygytgyn Sediments For Evidence Of Anoxia And Methane Cycling Over The Past 50,000 Years, Addie R. Holland

Masters Theses 1911 - February 2014

Compound specific isotope analysis of lake sediments is a powerful tool in deciphering evidence of changing climatic and paleoenvironmental conditions through time. Isotopic analysis of Lake El’gygytgyn pilot sediment cores, PG1351 and LZ1029, have contributed increased insight into paleoenvironmental interpretations regarding conditions of permanent ice cover and water column anoxia at the lake over the past 250 kyr. Bulk sediment δ15N was measured as a proxy for denitrification and a possible indicator for water column anoxia intensity. However, it appears that insufficient quantities of water column nitrate to fuel denitrification make its correlation with anoxia intensity ineffective. In pilot core …

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Understanding The Depth And Nature Of Flow Systems In The Nashoba Terrane, Eastern Massachusetts, U.S.A., John P. Diggins Jan 2009

Understanding The Depth And Nature Of Flow Systems In The Nashoba Terrane, Eastern Massachusetts, U.S.A., John P. Diggins

Masters Theses 1911 - February 2014

Igneous and metamorphic rock units have long been considered marginal aquifers yet they are a significant source for potable drinking water in many areas worldwide. Additionally, use of these systems is on the rise due to many factors including, contamination and overuse of surficial systems, as well as expanding population and drought. The Nashoba Terrane is a fault-bounded block of high-grade, steeply dipping metavolcanic and metasedimentary rock located in eastern Massachusetts, U.S.A. The Nashoba is northeast trending, extending from Oxford, MA to the Gulf of Maine south of Newburyport, MA. Seventeen previously drilled wells throughout the Nashoba were selected for …

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Drag Reduction In Turbulent Flows Over Micropatterned Superhydrophobic Surfaces, Robert J. Daniello Jan 2009

Drag Reduction In Turbulent Flows Over Micropatterned Superhydrophobic Surfaces, Robert J. Daniello

Masters Theses 1911 - February 2014

Periodic, micropatterned superhydrophobic surfaces, previously noted for their ability to provide drag reduction in the laminar flow regime, have been demonstrated capable of reducing drag in the turbulent flow regime as well. Superhydrophobic surfaces contain micro or nanoscale hydrophobic features which can support a shear-free air-water interface between peaks in the surface topology. Particle image velocimetry and pressure drop measurements were used to observe significant slip velocities, shear stress, and pressure drop reductions corresponding to skin friction drag reductions approaching 50%. At a given Reynolds number, drag reduction was found to increase with increasing feature size and spacing, as in …

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Characteristics Of Fish Yolk Proteins And A Method For Inducing Vitellogenin, Sean M. Lucey Jan 2009

Characteristics Of Fish Yolk Proteins And A Method For Inducing Vitellogenin, Sean M. Lucey

Masters Theses 1911 - February 2014

Teleosts are one of the most diverse groups of vertebrates. They utilize a wide array of reproductive strategies and tactics to overcome the challenges of the many ecological niches they inhabit. The most common reproductive method for teleosts is oviparity. Oviparous animals lay eggs with little or no embryonic development from the mother. The embryos are supplied with nutrition via yolk. Vitellogenesis is the process of the ovary sequestering yolk. It is regulated by exogenous environmental cues that act on the hypothalamus-pituitary-gonad axis. Through a series of hormonal controls, the liver produces the yolk precursor, vitellogenin. Vitellogenin is secreted by …

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Three-Dimensionally Preserved Arthropods From The Cambrian (Furongian) Of Quebec And Wisconsin: Systematics, Phylogeny, Ichnology, And Taphonomy, Joseph H. Collette Jan 2009

Three-Dimensionally Preserved Arthropods From The Cambrian (Furongian) Of Quebec And Wisconsin: Systematics, Phylogeny, Ichnology, And Taphonomy, Joseph H. Collette

Masters Theses 1911 - February 2014

Three new types of arthropod from Cambrian intertidal lithofacies of the Elk Mound Group and Lodi Member of Wisconsin, and the Potsdam Group of Quebec are described. These arthropods are preserved ventrally in three dimensions – allowing detailed characterization of morphology. Arenocaris inflata, from the Furongian Elk Mound Group and St. Lawrence Formation, is the earliest occurrence of a phyllocarid. Mosineia macnaughtoni, a large (>10 cm long) euthycarcinoid arthropod, also occurs in Elk Mound strata. Mictomerus melochevillensis represents a new family of early euthycarcinoids, and is a large (8–10+ cm long) arthropod with eleven pairs of homopodous, uniramous limbs. …

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Using The Oxidation State Of Iron Plagioclase To Evaluate Magma Oxygen Fugacity: A Micro-Xanes Study, Don Lac Jan 2009

Using The Oxidation State Of Iron Plagioclase To Evaluate Magma Oxygen Fugacity: A Micro-Xanes Study, Don Lac

Masters Theses 1911 - February 2014

No abstract provided.

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Conservation Implications Of A Marbled Salamander, Ambystoma Opacum, Metapopulation Model, Ethan B. Plunkett Jan 2009

Conservation Implications Of A Marbled Salamander, Ambystoma Opacum, Metapopulation Model, Ethan B. Plunkett

Masters Theses 1911 - February 2014

Amphibians are in decline globally and a significantly greater percentage of ambystomatid salamander species are in decline relative to other species; habitat loss contributes significantly to this decline. The goals of this thesis is to better understand extinction risk in a marbled salamander (ambystoma opacum) population and how forestry effects extinction risk. To achieve this goal we first estimated an important life history parameter (Chapter 1) then used a metapopulation model to estimate population viability and determine what aspects of their life history put them most at risk (Chapter 2) and finally predicted extinction risk in response to hypothetical forestry …

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Documenting The History Of Oxygen Depletion In Lake St. Croix, Minnesota, Using Chironomidae Remains In The Sedimentary Record, Caitlin E. Stewart Jan 2009

Documenting The History Of Oxygen Depletion In Lake St. Croix, Minnesota, Using Chironomidae Remains In The Sedimentary Record, Caitlin E. Stewart

Masters Theses 1911 - February 2014

Lake St. Croix is a natural impoundment located at the southern end of the St. Croix River. Land use changes since European settlement (c. 1850) have resulted in nutrient runoff, eutrophication, and periodic oxygen depletion in the hypolimnion of Lake St. Croix. Establishing sound lake management practices requires knowledge of historical conditions obtained through paleoecological studies. Remains of non-biting midges (Insecta: Diptera Chironomidae) in lake sediments have been shown to be reliable indicators of past hypolimnetic oxygen conditions. Cores from two sub-basins in the lake were collected in 2006. Midge analysis indicated that shifts in species assemblages correspond to the …

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Environmental Reconstructions From Laminated Lake Sediments, Lake C3, Ellesmere Island, Canadian High Arctic, Kathryn S. Zalzal Jan 2009

Environmental Reconstructions From Laminated Lake Sediments, Lake C3, Ellesmere Island, Canadian High Arctic, Kathryn S. Zalzal

Masters Theses 1911 - February 2014

Sediments in Lake C3, Ellesmere Island, Canada, contain annual laminations, providing a record of sediment accumulation for 1900+ years. Marine sediments are also present at base of cores, recording lake isolation following isostatic rebound of the Taconite Inlet region in the mid-Holocene. Beyond weak correlations with snowfall and summer temperature and precipitation, varve thickness comparisons with instrumental data were largely unsuccessful, likely due to turbidite-induced erosion. However, summer climate conditions are of key importance in varve thicknesses at many Arctic sites and we expect this to be true at Lake C3. Trends in the thickness record also correspond in approximate …

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System Performance Of Absolute Quartz-Crystal Barometers With Sub-Microbar Precision, Ganesh Kumar Subramanian Ananthanarayanan Jan 2009

System Performance Of Absolute Quartz-Crystal Barometers With Sub-Microbar Precision, Ganesh Kumar Subramanian Ananthanarayanan

Masters Theses 1911 - February 2014

In this thesis, the performance of absolute quartz-crystal barometers is presented, and their ability to measure, with sub-microbar precision, atmospheric pressure fluctuations with periods as short as a few seconds is demonstrated. The first observations of ocean-generated atmospheric infrasound with periods of about 5 s and sub-microbar amplitudes, called microbaroms, using single absolute barometers are presented. These barometers can measure microbaroms with amplitudes down to 50 nanobars and the 1-h estimates of microbarom amplitudes calculated from data collected independently with three collocated barometers differed by only a few nanobars. The observed microbaroms have amplitudes between 0.2 microbars and 1 microbar …

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Effects Of Anthropogenic Stage Fluctuations On Surface Water/Ground Water Interactions Along The Deerfield River, Massachusetts., Brandon J. Fleming Jan 2009

Effects Of Anthropogenic Stage Fluctuations On Surface Water/Ground Water Interactions Along The Deerfield River, Massachusetts., Brandon J. Fleming

Masters Theses 1911 - February 2014

Understanding the connection of surface waters to ground-water systems is important when evaluating potential water resources. In the past surface waters and ground-water have been viewed as two different sources of water but more commonly now they are viewed as one connected resource (Winter et al, 1998). The nature of connection between surface and ground-waters varies depending on climatic and geologic settings, as well as anthropogenic influences such as ground-water pumping and manipulation of river flows by dams. This thesis takes advantage of daily stage changes in the Deerfield River to investigate surface water interactions with ground-water in Charlemont, MA. …

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Petrology, Structural Geology, And Significance Of Mn-Andalusite From The Lower Ortega Quartzite, Tusas Mts., Nm, Usa, Nancy A. Price Jan 2007

Petrology, Structural Geology, And Significance Of Mn-Andalusite From The Lower Ortega Quartzite, Tusas Mts., Nm, Usa, Nancy A. Price

Masters Theses 1911 - February 2014

The Proterozoic syn-orogenic supra-crustal package exposed in the Tusas Mountain Range in northern New Mexico includes the anomalously thick, clean, ultramature Ortega Formation quartzite (Bauer and Williams, 1989). A unique Mn-bearing horizon spans the basal contact of the quartzite and contains Mn-andalusite, quartz, hematite, rutile, zircon, monazite, phyllosilicates, and locally kyanite and gahnite in intermittent aluminous, hematite-bearing layers, on the surface of cross-beds, concentrated in high strain zones, and on cleavage planes. Large-scale Mn zoning in Mn-andalusite results from a decrease in Mn content away from localized Mn highs (XMn of up to 0.76) that commonly correspond with the location …

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Transfer Function And Impulse Response Synthesis Using Classical Techniques, Sonal S. Khilari Jan 2007

Transfer Function And Impulse Response Synthesis Using Classical Techniques, Sonal S. Khilari

Masters Theses 1911 - February 2014

This thesis project presents a MATLAB based application which is designed to synthesize any arbitrary stable transfer function. Our application is based on the Cauer synthesis procedure. It has an interactive front which allows inputs either in the form of residues and poles of a transfer function, in the form of coefficients of the numerator and denominator of the transfer impedance or in the form of samples of an impulse response. The program synthesizes either a single or double resistively terminated LC ladder network. Our application displays a chart showing the variation of stability of an impulse response with the …

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A Study Of A Reimaging System For Correcting Large-Scale Phase Errors In Reflector Antennas, Eugene F. Lauria Jan 1992

A Study Of A Reimaging System For Correcting Large-Scale Phase Errors In Reflector Antennas, Eugene F. Lauria

Masters Theses 1911 - February 2014

This thesis investigates a new approach for dealing with the adverse effects of large-scale deformations in the main reflector of large Cassegrain antennas. In this method, the incident aperture distribution is imaged onto a tertiary focal plane. This is accomplished by using an optical imaging system consisting of a lens mounted behind the Cassegrain focus of the antenna. The lens forms a real image of the product of the incident aperture distribution and the pupil function of the antenna. The pupil function describes the profile of the main reflector of the antenna. If the incident aperture distribution is a plane …

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