Physical Sciences and Mathematics Commons^™

A Precision Measurement Of The Lifetime Of The Positive Muon, Kevin Louis Giovanetti

Dissertations, Theses, and Masters Projects

In an experiment performed at TRIUMF Laboratory, the time distribution of muon decay positrons arising from pions stopped in a water Cherenkov counter was measured with a high precision timing system. The pions served as a source of positive muons.;The data were used to determine a new value for the positive muon lifetime. This lifetime 2.19695 (+OR-) .00006 (sec) is slightly lower than previous measurements but still in fair agreement. The data were tested for the various systematic effects that typically occur in these measurements.

Wave Refraction By Warm Core Rings, George R. Mapp

Dissertations, Theses, and Masters Projects

No abstract provided.

Diffusion And Trapping Of Positive Muons In Niobium And In Aluminum Alloys, Muhammad Zillulhaq Numan

Dissertations, Theses, and Masters Projects

Zero, longitudinal and transverse magnetic field uSR has been used to investigate (mu)('+) diffusion and trapping in Nb. The ambiguity in the interpretation of the 'double humped' temperature dependence of the depolarisation rate for the transverse field case has been resolved. A discussion of how the zero and longitudinal measurements can distinguish between the trapping and detrapping phenomena is presented with (mu)SR data analysis in mind. Muon mobility is shown to increase monotonically with temperature. The width of the local magnetic field distribution due to Nb nuclear moments and the rate for trapping and detrapping of muons have been measured …

Experimental Studies Of Antiprotonic Atoms In Hydrogen And Helium, Jeffrey Robert Lindenmuth

Dissertations, Theses, and Masters Projects

In an experiment performed at Brookhaven National Laboratory the spectra of atomic x rays from stopped antiprotons in gaseous helium, liquid hydrogen, and gaseous hydrogen were measured. The measurements were performed at 1 atmosphere and 25(DEGREES)K for the gaseous target.;In the case of He the L and M series of p were observed and relative intensities measured. However in hydrogen no x rays were observed and thus only an upper limit of the yields of the K series in liquid and gaseous hydrogen were calculated.

Effects Of Disruptive Grazing By The Mud Snail Ilyanassa Obsoleta On Mudflat Nematode Populations, David Ludwig

Dissertations, Theses, and Masters Projects

Population densities of the mud snail Ilyanassa obsoleta were manipulated in caging experiments on a salt marsh mudflat and in laboratory microcosms. Mud snails outcompete nematodes for food resources, but may increase resources available to deposit feeding groups. Mud snails reduce annelid (polychaete and oligochaete) populations by substrate disruption. Reduced annelid densities provide the nematode community with some release from predation and competition. In mudflat sediments, the nematode community responds to both primary (predation) and secondary (envirorm1ental release, food competition) interactions. Multiple levels of interactive coupling should be considered in any systems level investigation in this habitat.

An Investigation Of Sand Transport Phenomena In The Rappahannock River Estuary, Virginia, Charles Joseph Natale

Dissertations, Theses, and Masters Projects

Quantitative evidence supplied by bottom sediment textural analysis, Fourier grain-shape analysis and Q-mode factor analysis indicate that river-borne sand-sized sediment originating in the upper reaches of the Rappahannock is actively transported downstream and ultimately delivered to the estuarine sediment regime. Current velocity observations in the upper estuary as well as suspended sediment concentrations measured at stream gaging stations, indicate that short-term extreme hydrological events such as periodic river flooding provide a plausible transport mechanism to move river-borne sands into the estuarine sediment regime.Events of this nature can disrupt average partly-mixed estuarine circulation patterns by displacing the salt-wedge to a more …

Zooplankton Communities In Chesapeake Bay Seagrass Systems, Cathy Elizabeth Meyer

Dissertations, Theses, and Masters Projects

No abstract provided.

Waterfowl Utilization Of A Submerged Vegetation (Zostera Marina And Ruppia Maritima) Bed In The Lower Chesapeake Bay, Elizabeth W. Wilkins

Dissertations, Theses, and Masters Projects

No abstract provided.

The Distribution And Ecology Of Gammaridean Amphipods In The Plankton Of The Middle Atlantic Bight, Cathy J. Womack

Dissertations, Theses, and Masters Projects

No abstract provided.

The Distribution Of Dissolved Silica And Particulate Biogenic Silica In The James, York And Rappahannock Estuaries, Virginia, Gary F. Anderson

Dissertations, Theses, and Masters Projects

No abstract provided.

Life History And Management Of Spiny Dogfish, Squalus Acanthias, Off The Northeastern United States, Marta Nammack

Dissertations, Theses, and Masters Projects

No abstract provided.

Utilization Of A Zostera Marina And Ruppia Maritima Habitat By Four Decapods With Emphasis On Callinectes Sapidus, Deborah L. Penry

Dissertations, Theses, and Masters Projects

No abstract provided.

Analysis Of Population And Price Aspects Of The Virginia Hard Clam (Mercenaria Mercenaria) Fishery, Andre C. Kvaternik

Dissertations, Theses, and Masters Projects

No abstract provided.

A [Mu]+Srstudy Of Uniaxial Stress Induced Symmetry Breaking In An Fe Single Crystal, Min. Namkung

Dissertations, Theses, and Masters Projects

For the first time, external uniaxial stress has been used in a (mu)('+)SR experiment. The stress dependences of the following parameters were obtained for Fe crystals: the muon precessional frequency, (nu)(,(mu)), the transverse (longitudinal) depolarization rates, 1/T(,2) (1/T(,1)), and F(,T)/F(,L), the ratio of the probabilities for the muon to find domains with transverse/longitudinal fields. The shift in (nu)(,(mu)) was -0.34 (+OR-) 0.023 MHz per 100 micro-strain along the -axis. Changes in other parameters depend on the sample history but they, in general, increase with stress.;External stress changes the muon occupational probability at each site which significantly affects the dipolar field …

Anisotrophy In Mhd Turbulence Due To A Mean Magnetic Field, John V. Shebalin

Dissertations, Theses, and Masters Projects

The development of anisotropy in an initially isotropic spectrum is studied numerically for two-dimensional magnetohydrodynamic (MHD) turbulence. The anisotropy develops due to the combined effects of an externally imposed dc magnetic field and viscous and resistive dissipation at high wave numbers. The effect is most pronounced at high mechanical and magnetic Reynolds numbers. The anisotropy is greater at the higher wave numbers.;The statistical structure of two-dimensional MHD turbulence is also considered. It is shown that the three known rugged invariants of the isotropic case reduce to two for the anisotropic case. Randomness and ergodicity are also briefly discussed.

A Study Of Nutritional Requirements Of The Larvae Of The American Oyster (Crassostrea Virginica), Fu-Lin E. Chu

Dissertations, Theses, and Masters Projects

The purpose of this study is to obtain information for the formulation of artificial diets for larvae of the American oyster (Crassostrea virginica) and to test procedures related to presenting these diets to the oyster larvae. In order to determine the nutrient components usually provided in larval diets, biochemical analyses of lipids and fatty acids, proteins and amino acids and polysaccharide carbohydrates were performed on five algae species used as a food source for oyster larvae. These algae are Chlorella sp., Pyramimonas virginica, Pseudoisochrysis paradoxa, Pavlova (Monochrysis) lutheri and Isochrysis galbana. The biochemical analyses indicate that the nutritional value of …

The Kara Sea: Geologic Structure And Water Characteristics, Donald B. Milligan

Dissertations, Theses, and Masters Projects

Movement of Atlantic Water into the Kara Sea is controlled by the bathymetry which funnels the inflow up three canyons along the eastern margin of the Svyataya Anna Trough. Mixing of the warm, saline Atlantic Water in these canyons with the considerable summer outflow of the Ob-Yenisey rivers results in the formation of Arctic Bottom Water and due to the presence and cooling by ice, in the formation of Arctic Surface Water. Both of these water masses then exit the Kara Sea as deep and shallow countercurrents to the incoming Atlantic Water. The northernmost canyon allows some Atlantic Water to …

The Feeding Ecology And Trophic Role Of The Northern Pipefish, Syngnathus Fuscus, In A Lower Chesapeake Bay Seagrass Community, Clifford H. Ryer

Dissertations, Theses, and Masters Projects

The purpose of this study is to examine the feeding ecology and trophic role/importance of the northern pipefish, Syngnathus fuscus, in a lower Chesapeake Bay seagrass community.

The study incorporates; 1) examination of stomach contents in conjunction with prey abundance data, inorder to arrive at conclusions concerning the food preferences of S· fuscus, 2) determination of daily feeding periodicities and stomach evacuation parameters, thus allowing for the determination of a daily ration for S· fuscus, 3) examination of size relationships between S. fuscus and it's major prey species, 4) estimation of pipefish densities at the study site, and 5) examination …

Aspects Of The Nutritional Ecology Of Sagitta Tenuis (Chaetognatha) In The Lower Chesapeake Bay, Michael F. Canino

Dissertations, Theses, and Masters Projects

No abstract provided.

Fish Predator-Prey Interaction In Areas Of Eelgrass (Zostera Marina), Joseph Lascara

Dissertations, Theses, and Masters Projects

No abstract provided.

Reproductive Biology And Recreational Fishery For Spotted Seatrout, Cynoscion Nebulosus, In The Chesapeake Bay Area, Nancy J. Brown

Dissertations, Theses, and Masters Projects

No abstract provided.

Interpretation Of Gc-Ms Data By Reverse Search And Relative Retention Indices, Christopher Hein

Dissertations, Theses, and Masters Projects

No abstract provided.

The Status Of Marine Turtles In Chesapeake Bay And Virginia Coastal Waters, Maryellen Lutcavage

Dissertations, Theses, and Masters Projects

No abstract provided.

The Socioeconomic And Fisheries Characteristics Of Virginia's Commercial Sport Fishing Industry, Anne R. Marshall

Dissertations, Theses, and Masters Projects

No abstract provided.

Macrobenthic Community Structure In The Vicinity Of An Oil Refinery: A Consideration Of Sampling Design And Statistical Technique, Priscilla Hinde

Dissertations, Theses, and Masters Projects

No abstract provided.

Ultrasonic Determination Of Thermoelastic Properties Of Stressed Solids, Engmin J. Chern

Dissertations, Theses, and Masters Projects

We present a thermoelastic derivation of ultrasonic waves propagating in a solid in which an applied homogeneous stress is superimposed on a nonzero initial stress. We also derive the temperature dependence of the elastic coefficients and the linear relationship between the applied stress and a newly defined parameter--the thermal acoustic constant. The stress acoustic constant is defined and its relationship to the acoustic natural velocity is discussed. Experimental considerations pertinent to the ultrasonic measurement techniques used in the investigation are described. The results of the stress-strain and thermal strain experiments verify the predictions of the theory. Finally, we derive an …

Phosphorus-31 Knigh Shifts In Amorphous Nickel-Phosphorus And Nickel-Cobalt-Phosphorus Alloys, Paul Stuart Gustafson

Dissertations, Theses, and Masters Projects

Amorphous alloys of the form Ni(,1-x)P(,x) and (Ni(,1-y)Co(,y))(,1-x)P(,x) were prepared by two methods, electroplating (EP) and electroless deposition (EL). Two metastable phases of differing physical densities and NMR properties were noted, and analysed by measurement of the Knight Shifts, relaxation times, physical densities, etc. A comparison is made between the data and a hybridized band model which yields an expression for the enhanced susceptibility of the phosphorous valence band.

The Structure Of Axisymmetric Turbulence, Charles W. Smith

Dissertations, Theses, and Masters Projects

A wide range of laboratory and naturally occurring plasmas are frequently attributed a fluid description and as such, demonstrate turbulent flows. We will investigate a variety of forms which may be taken by the correlation functions of these turbulent flows. The most commonly discussed isotropic symmetry is not generally applicable since most systems of interest have been shown to be strongly anisotropic. This thesis will develop an axi-symmetric description from which the magnetic helicity may be extracted together with its spectrum. This description will be compared to the form taken by axi-symmetric, helical Navier Stokes turbulence which will also be …

Nmr In Amorphous Vanadium Alloys, Larry Mattix

Dissertations, Theses, and Masters Projects

Amorphous alloys of VAl and VSi have been prepared by a process of r.f. sputtering onto cryogenic substrates. The Nuclear Magnetic Resonance has been examined in an effort to understand how the electronic structure of these amorphous alloys compares to that of the corresponding crystalline alloys, and to extend the study of the electronic properties of these alloy systems into composition ranges where the crystalline alloys do not exist, because of solubility limits.;The Al('27) and V('51) Knight shifts were measured at 77(DEGREES)K and 300(DEGREES)K, for Al concentrations extending from 15 to 85 atomic percent, in amorphous VAl. The results are …

Influence Of Marinas On Hydrocarbons In Sediments Of Two Estuarine Creeks, Evangelos Alexandros Voudrias

Dissertations, Theses, and Masters Projects

No abstract provided.