Physical Sciences and Mathematics Commons^™

Vorticity Dynamics Of Seasonal Variations Of The Antarctic Circumpolar Current From A Modeling Study, John M. Klinck

CCPO Publications

A one-layer numerical model was developed to analyze the vorticity dynamics of the seasonal variations of currents in the Southern Ocean. The model includes the continental geometry and bathymetry of the Southern Ocean and is forced by monthly climatological wind stress. Five cases are considered that compare (i) circulation over a flat bottom to that with bathymetry, (ii) effects of zonally averaged wind stress forcing versus the climatological forcing and (iii) anomaly wind stress (winds with the annual mean removed) versus the full stress. The individual terms in the vorticity conservation equation are calculated from the model solution along two …

Lava-Seawater Interactions At Shallow-Water Submarine Lava Flows, Francis J. Sansone, Joseph A. Resing, Gordon W. Tribble, Peter N. Sedwick, Kevin M. Kelly, Ken Hon

OES Faculty Publications

Hydrothermal plumes associated with nearshore lava flows from Kilauea Volcano, Hawaii were studied on five occasions during 1989-1990 to address the current lack of data on direct lava-seawater interactions. The following enrichments were found in the sea-surface hydrothermal plumes above the active underwater lava flows: H₂, 15,000x ambient seawater concentrations; Mn, 250x; and Si, 20x. Water temperatures reached 46°C. Lower concentrations and temperatures were observed in the plumes with increasing distance from shore, with H₂, Si, and Mn concentrations linearly related to seawater temperature. Unlike deep sea spreading center hydrothermal plumes, no CH₄ enrichment was …

Distribution Of Terrestrially Derived Dissolved Organic Matter On The Southeastern United States Continental Shelf, Mary Ann Moran, Lawrence R. Pomeroy, Edward S. Sheppard, Larry P. Atkinson, Robert E. Hodson

CCPO Publications

Dissolved lignin-derived compounds in seawater indicate the presence of organic matter originating from vascular plants and therefore from terrestrial (upland and coastal marsh) ecosystems. We used a hydrophobic resin to concentrate lignin-rich humic substances and to determine concentrations of lignin oxidation products (vanillyl lignin phenols) for waters of the continental shelf of the southeastern U.S. Lignin phenol concentrations ranged from 0.05 to 4.2µg liter‒1 and accounted for 0.002–0.13% of the total dissolved organic carbon (DOC) pool in continental shelf waters. Dissolved lignin concentrations were generally highest near the shore and in those areas receiving greatest river and marsh …

Assessment Of Organic And Metal Contaminants In Lower Back Bay And Upper Currituck Sound, Kate Benkert

V. Poster Abstracts

Studies were conducted at Mackay Island National Wildlife Refuge in 1988 and 1989 to provide baseline data for an assessment of organic chemicals and metal contaminants in the aquatic ecosystem. Longnose gar, gizzard shad, snapping turtles, common rangia clams and sediments were collected from sites in lower Back Bay and upper Currituck Sound for contaminant analyses.

Composite sediment samples were analyzed for the presence of metals, organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs). Organochlorine pesticides were not detected in the sediments. Various PAH compounds were detected in the sediments, although at trace concentrations which just exceeded the analytical detection limit …

Environmental Education: A Chance For The Future, Ben Mathias

V. Poster Abstracts

The U.S. Fish and Wildlife Service is committed to providing environmental education opportunities for the Nation's student body. Local, regional and national educators are invited to investigate and utilize the resources of Back Bay National Wildlife Refuge with their colleagues and students. Teacher workshops at the Refuge provide orientation to Refuge lands, outdoor classroom sites, trails, interpretive facilities and equipment, and potential field activities. Refuge staff members are available to assist with: • Preliminary planning • Group scheduling • Library research • Workshop registration • Trip logistics and • On-site group orientation. Most classroom sites, associated trails/boardwalks, and Visitor Contact …

Some Aspects Of The Semi-Perfect Elimination, Stephan Olariu

Computer Science Faculty Publications

Several efficient algorithms have been proposed to construct a perfect elimination ordering of the vertices of a chordal graph. We study the behaviour of two of these algorithms in relation to a new concept, namely the semi-perfect elimination ordering, which provides a natural generalization of chordal graphs.

Seasonal Phytoplankton Assemblages Associated With The Chesapeake Bay Plume, Harold G. Marshall

Biological Sciences Faculty Publications

Waters associated with the Chesapeake Bay plume were highly variable, unstable, and subject to the influence of flow patterns into and out of the Bay. Seasonal phytoplankton assemblages were identified for this region, with the phytoplankton development similar to the seasonal spring-fall growth maxima over the shelf, yet influenced by the multi-pulsed patterns often noted in the lower Bay. Major dominants included species common to both the shelf and lower Chesapeake Bay.

Observations Of The Phytoplankton Standing Crop At The Shelf Margin Of The Mid Atlantic Bight, Bruce B. Wagoner, Harold G. Marshall

Biological Sciences Faculty Publications

A comparison of the total percentage cell abundance and cell biovolume relationships of major phytoplankton categories was made between two station sets across the shelf margin. Diatom values for abundance and biovolume were greater at oceanic stations compared to the outer shelf stations, with dinoflagellates having the reverse pattern. The composite contributions to biovolume and abundance in the standing crop from other phytoplankton categories were greater over the outer shelf than beyond the shelf margin. The major source of biovolume (biomass) from the outer shelf and these oceanic stations came from the diatoms and dinoflagellates, with an average mean of …

Rx For Success At Back Bay National Wildlife Refuge: Take Two Committed Partners-Add Water, Janet Taylor, Julia Herrick, Ben Mathias

V. Poster Abstracts

As part of a major effort to improve habitats for waterfowl and other wetland-dependent wildlife, Ducks Unlimited, Inc. is contributing $187,500 in matching funds to help the U.S. Fish and Wildlife Service rehabilitate wetland impoundments at Back Bay NWR.

The three-year project will increase Refuge management capabilities on existing wetland areas, create 300 acres of new marsh habitat and increase water management flexibility throughout the impoundment system. Components of the project include:

• Raising and re-sloping 8 miles of existing dikes
• Installing 13 new water control structures
• Constructing 6,000 feet of new dikes
• Creating two storage pools totalling 53 acres and …

Refuge Land Acquisition: Helping Preserve Back Bay's Wildlife Heritage, Julia Herrick, Ben Mathias, Janet Taylor

V. Poster Abstracts

The once-renowned waterfowl populations and bass fishery of Back Bay, Virginia have declined dramatically in recent years. Lands surrounding Back Bay are increasingly threatened by on-going and potential land development. These lands serve as an important filter for pollutant and sediment-laden runoff from adjacent areas. The boundary of the Back Bay National Wildlife Refuge was expanded in 1989 to include an additional 6,340 acres of brackish marsh, forested swamp, and "critical edge" upland habitat, important to a variety of wildlife species and for its natural filtering effect. Within the U.S. Fish and Wildlife Service's policy of working with willing sellers, …

Gulf Stream Frontal Eddy Influence On Productivity Of The Southeast United States Continental Shelf, Thomas N. Lee, James A. Yoder, Larry P. Atkinson

CCPO Publications

Weekly period meanders and eddies are persistent features of Gulf Stream frontal dynamics from Miami, Florida, to Cape Hatteras, North Carolina. Satellite imagery and moored current and temperature records reveal a spatial pattern of preferred regions for growth and decay of frontal disturbances. Growth regions occur off Miami, Cape Canaveral, and Cape Fear due to baroclinic instability, and decay occurs in the confines of the Straits of Florida between Miami and Palm Beach, between 30° and 32°N where the stream approaches the topographic feature known as the Charleston bump and between 33°N and Cape Hatteras. Eddy decay regions are associated …

A Mergeable Double-Ended Priority Queue, S. Olariu, Z. Wen

Computer Science Faculty Publications

An implementation of a double-ended priority queue is discussed. This data structure referred to as min–max–pair heap can be built in linear time; the operations Delete-min, Delete-max and Insert take O(log n) time, while Find-min and Find-max run in O(1) time. In contrast to the min-max heaps, it is shown that two min–max–pair heaps can be merged in sublinear time. More precisely, two min–max–pair heaps of sizes n and k can be merged in time O(log (n/k) * log k).

On A Unique Tree Representation For P4-Extendible Graphs, B. Jamison, S. Olariu

Computer Science Faculty Publications

Several practical applications in computer science and computational linguistics suggest the study of graphs that are unlikely to have more than a few induced paths of length three. These applications have motivated the notion of a cograph, defined by the very strong restriction that no vertex may belong to an induced path of length three. The class of P₄-extendible graphs that we introduce in this paper relaxes this restriction, and in fact properly contains the class of cographs, while still featuring the remarkable property of admitting a unique tree representation. Just as in the case of cographs, the …

Nonlinear-Interaction Of A Detonation Vorticity Wave, D. G. Lasseigne, T. L. Jackson, M. Y. Hussaini

Mathematics & Statistics Faculty Publications

The interaction of an oblique, overdriven detonation wave with a vorticity disturbance is investigated by a direct two-dimensional numerical simulation using a multidomain, finite-difference solution of the compressible Euler equations. The results are compared to those of linear theory, which predict that the effect of exothermicity on the interaction is relatively small except possibly near a critical angle where linear theory no longer holds. It is found that the steady-state computational results whenever obtained in this study agree with the results of linear theory. However, for cases with incident angle near the critical angle, moderate disturbance amplitudes, and/or sudden transient …

The Kinetics Of Organic Matter Mineralization In Anoxic Marine Sediments, David J. Burdige

OES Faculty Publications

The kinetics of sulfate reduction and inorganic nutrient production (ΣCO_2, ammonium, and phosphate) were examined in the sediments at five sites in the southern Chesapeake Bay, using long term (> 200 d) sediment decomposition experiments. Average first order rate constants for these processes (at 25^oC) decreased from 8.2 to 3.7 yr^-1 in the surface sediments (0-2 cm), to 2.1 to 0.2 yr^-1 at 12-14 cm. The C/N and C/P ratios of the organic matter undergoing decomposition also increased with depth at these sites. Taken together, these results indicate that the reactivity of the organic matter …

Observations Of A Cyclonic Ring: Gulf Stream Coalescence Event Over The Blake Plateau, Julie Mcclean-Padman, Larry P. Atkinson

CCPO Publications

Hydrographic data collected in September 1980 over the Blake Plateau were analyzed using a combination of empirical search and inverse techniques. Five sections, extending from the continental shelf break eastward across the Blake Plateau, were positioned at approximately 1-degrees intervals between 28-degrees and 32-degrees-N. The empirical search procedure was applied to four closed regions (boxes), constructed from adjacent sections, where each region was assumed to consist of two conservative layers. Five geostrophic velocity sections were obtained using the average optimum reference level for the four boxes. The inverse technique provided barotropic correction velocities that caused all layers to conserve mass. …

Lingin Derived Organic Matter In Georgia Coastal Waters, Mary Ann Moran, Lawrence R. Pomeroy, Edward S. Sheppard, Larry P. Atkinson

CCPO Publications

The importance of riverine- and saltmarsh-derived organic matter to the food web of Georgia coastal waters has been a focus of ecological research over the past thirty years. Studies based on energy budgets, carbon flux measurements, and stable isotope ratios have generally implicated marsh detritus as an important, although not always dominant, source of organic matter within the marshes and adjacent estuaries (Teal 1962, Odum and de la Cruz 1967, Haines 1977, Peterson and Howarth 1987). However, data on the contribution of exported marsh and riverine organic matter to productivity futher offshore, in continental shelf waters off the coast of …

Parametric Instability Of Supersonic Shear Layers Induced By Periodic Mach Waves, Fang Q. Hu, Christopher K. W. Tam

Mathematics & Statistics Faculty Publications

It is suggested that parametric instability can be induced in a confined supersonic shear layer by the use of a periodic Mach wave system generated by a wavy wall. The existence of such an instability solution is demonstrated computationally by solving the Floquet system of equations. The solution is constructed by means of a Fourier-Chebyshev expansion. Numerical convergence is assured by using a very large number of Fourier and Chebyshev basis functions. The computed growth rate of the induced flow instability is found to vary linearly with the amplitude of the mach waves when the amplitude is not excessively large. …

Best Lp Aapproximation With Multiple Constraints For 1 ⩽ P < ∞, J. J. Swetits, S. E. Weinstein, Yuesheng Xu

Mathematics & Statistics Faculty Publications

The problem considered in this paper is best L_p approximation with multiple constraints for 1 ⩽ p < ∞. Characterizations of best L_p approximations from multiple n-convex splines and functions are established and the relationship between them is investigated. Applications to best monotone convex approximation are studied.

A Duality Approach To Best Uniform Convex Approximation, S. E. Weinstein, Yuesheng Xu

Mathematics & Statistics Faculty Publications

Let C[a, b] be the space of continuous functions on [a, b] endowed with the uniform norm llƒll _∞ = sup{ Iƒ(x)1 :x∈ [a, b]}. Let K be the set of convex functions defined on [a, b]. A function g* ∈ K is said to be a best uniform convex approximation to ƒ ∈ C[a, b] if ∥ƒ - g*∥ _∞ = inf { ∥ƒ - g∥_∞ : g ∈ K}.

Self-Activation And Inhibition: A Simple Nonlinear Model, J. A. Adam

Mathematics & Statistics Faculty Publications

Self-activation and self-inhibition of cell number density (or growth factor concentration) due to a spatially localized source are studied. Both the time-independent and time-dependent models are examined, and the linear stability of the resulting three steady states of the former is discussed.

Activator-Inhibitor Control Of Tissue Growth, John A. Adam

Mathematics & Statistics Faculty Publications

This note develops a simple model for the competition between activator and inhibitor control mechanisms in one-dimensional tissue growth. The pedagogic usefulness of such a model is that it is easily accessible to undergraduate applied mathematicians and is suggestive of behavior known to occur in more realistic biological systems (e.g., some types of cancer). The limitations of the model are obvious and can provide a basis for discussion of the applicability of complementary levels of description in mathematical modeling.

Trace Elements In Estuarine And Coastal Waters: U.S. Studies From 1986-1990, Gregory A. Cutter

OES Faculty Publications

The use of specialized analytical techniques, field studies, controlled laboratory experiments, and geochemical modeling have allowed U.S. investigators to expand our understanding of trace element cycling in coastal waters and estuaries. Considerable emphasis has been placed on quantifying the flux of trace elements within and through the coastal zone. In addition, substantial progress has been made in identifying the chemical speciation of many trace elements, providing a linkage between the geochemical and biochemical behavior of these elements. Another significant advance has been the use of trace elements as tracers of geochemical processes and water masses in the coastal environment.

Hydrogen Sulfide And Radon In And Over The Western North Atlantic Ocean, T. W. Andreae, Gregory A. Cutter, N. Hussain, J. Radford-Knoery, M. O. Andreae

OES Faculty Publications

Atmospheric measurements of radon and hydrogen sulfide, and seawater measurements of total sulfide, free sulfide, and carbonyl sulfide, were made on a cruise in the western North Atlantic Ocean (October 24 to November 9, 1989). Measured values for ²²²Rn ranged from 3 to 70 pCi m⁻³, those for atmospheric hydrogen sulfide from 1 to 85 parts per trillion, and those for dissolved total and free sulfide in seawater from 33 to 930 pmol L⁻¹ and 0 to 73 pmol L⁻¹, respectively. A positive correlation between ²²²Rn and atmospheric H₂S was observed. …

Development And Evaluation Of Tracer Particles For Use In Microzooplankton Herbivory Studies, Mary Putt

OES Faculty Publications

Two methods of preparing algae for use as tracer particles in single species measurements of microzooplankton herbivory were evaluated. Algae were either heat-killed and labelled with 5-(4,6-dichlorotriazin-2-yl amino fluorescein) (DTAF) (Rublee & Gallegos 1989; Mar, Ecol. Prog. Ser. 51: 221-227) or stained with hydroethidine (HYD). Both DTAF and HYD-stained algae were readily visible within the digestive vacuoles of most microzooplankton collected in estuarine and coastal waters of Massachusetts (USA) and preserved with Lugol's iodine. However, DTAF was ineffective at staining several chromophytic algae and the heat-kill process reduced cell volume by ≥ 50% in several of the algae which were …

Second Coefficient Of Viscosity In Air, Robert L. Ash, Allan J. Zuckerwar, Zhonquan Zheng

Mechanical & Aerospace Engineering Faculty Publications

Acoustic attenuation measurements in air were analyzed in order to estimate the second coefficient of viscosity. Data over a temperature range of 11 C to 50 C and at relative humidities between 6 percent and 91 percent were used. This analysis showed that the second coefficient of viscosity varied between 1900 and 20,000 times larger than the dynamic or first coefficient of viscosity over the temperature and humidity range of the data. In addition, the data showed that the molecular relaxation effects, which are responsible for the magnitude of the second coefficient of viscosity, place severe limits on the use …

Electric Field Induced Emission As A Diagnostic Tool For Measurement Of Local Electric Field Strengths, A. N. Dharamsi, K. H. Schoenbach

Bioelectrics Publications

The phenomenon of electric field induced (EFI) emission is examined in several diatomic and polyatomic molecules. The possibility of using this phenomenon as a diagnostic tool to measure, nonintrusively, the strength and direction of local electric fields in plasmas is discussed. An estimate of the EFI signal emitted in a typical application plasma is given. This yields a lower bound on the detector sensitivity necessary to exploit EFI emission in practical applications. It is concluded that, at present, the EFI signal could be measured by some very sensitive infrared detection schemes available. Current progress in infrared detector technology, if maintained, …

The Effect Of Age Misreporting In China On The Calculation Of Mortality Rates At Very High Ages, Ansley J. Coale, Shaomin Li

Management Faculty Publications

When mortality rates by age are calculated from recorded deaths and enumerated populations, rates at higher ages are typically in error because of misstated ages. Mortality rates for China in 1981 have been calculated from the number of deaths in 1981 in each household recorded in the 1982 census, and from the census population back-projected one year. Because age was determined from date of birth, and because persons of the Chinese culture have very precise knowledge of date of birth, the mortality rates even at high ages should be unusually accurate. This expectation is fulfilled for most of China, but …

Role Of Surface Morphology In Wafer Bonding, W.P. Maszara, B.L. Jiang, A. Yamada, G.A. Rozgonyi, H. Baumgart, A.J.R. De Kock

Electrical & Computer Engineering Faculty Publications

The strain patterns detected by x-ray topography in wafers bonded for silicon-on-insulator (SOI) technology were found related to the flatness nonuniformity of the original wafers. Local stresses due to the bonding process are estimated to be about 1×10⁸ dynes/cm². The stress is reduced about 100 times for the thin (0.5 μm) SOI films. Most of the wafer deformation occurs during room temperature mating of the wafers. The deformation is purely elastic even at 1200 °C. The magnitude of the stress appears insignificant for complimentary metal-oxide-semiconductor devices performance.