Physical Sciences and Mathematics Commons^™

Water!, Kirk J. Havens, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.

Distribution Of Submerged Aquatic Vegetation In The Chesapeake Bay And Tributaries And Chincoteague Bay - 1994, R J. Orth, Judith F. Nowak, Gary F. Anderson, David J. Wilcox, Jennifer R. Whiting, Leah S. Nagy

Reports

No abstract provided.

Investigation Of Isolated Sand Shoals On The Inner Shelf Of Virginia Relative To The Potential For Aggregate Mining : Report On Task 4, Possible Physical Impact Of Dredging At Sandbridge Shoal Of The 1993-1995 U. S. Minerals Management Service - Commonwealth Of Virginia Cooperative Project, Jerome P.-Y. Maa

Reports

The Virginia Institute of Marine Science, together with other state agencies, has a continuing interest in preserving the coastline of Virginia, particularly, the Atlantic coastline in the vicinity of the resort city of Virginia Beach. Because a well maintained beach can serve several purposes, e.g., (1) providing public recreational areas, (2) protecting valuable properties that are located near coastline, and (3) reducing the rate of land loss, a great deal of efforts has been devoted to understand the processes that affect the change of shoreline. Among several erosion forces, waves are especially important elements as they can alter the shoreline …

The Magnitude And Persistence Of Soil No, N2o, Ch4, And Co, Fluxes From Burned Tropical Savanna In Brazil, M Poth, Iris C. Anderson, Et Al

VIMS Articles

Among all global ecosystems, tropical savannas are the most severely and extensively affected by anthropogenic burning. Frequency of fire in cerrado,a type of tropical savanna covering 25% of Brazil, is 2 to 4 years. In 1992 we measured soil fluxes of NO, N2O, CH4, and CO2 from cerrado sites that had been burned within the previous 2 days, 30 days, 1 year, and from a control site last burned in 1976. NO and N2O fluxes responded dramatically to fire with the highest fluxes observed from newly burned soils after addition of water. Emissions of N-trace gases after burning were of …

Recurrences Associated With A Classical Orbit In The Node Of A Quantum Wave Function, John A. Shaw, John B. Delos, Michael Courtney, Daniel Kleppner

Arts & Sciences Articles

Absorption spectra of atoms in magnetic fields reveal recurrences: manifestations of classical orbits (or quantum wave packets) that go out from the atom and later return. A formula from closed-orbit theory asserts that if the orbit lies on a node of the outgoing wave function, then the strength of the recurrence is zero. New quantum calculations, however, show that the recurrence strength is nonzero, though small. We derive a semiclassical formula for the recurrence strength associated with a classical orbit at a node of the quantum wave function. This formula is compared to the quantum mechanical calculation. Compared to …

Organization Of Sequences Of Bifurcations Of Periodic Orbits, D. A. Sadovskii, J. A. Shaw, John B. Delos

Arts & Sciences Articles

Numerical calculations have shown that bifurcations of periodic orbits of Hamiltonian systems often occur in organized groups. Normal-form theory provides an explanation.

Public Beach Assessment Report Huntington Park, Anderson Park, And King-Lincoln Park City Of Newport News, Virginia, Donna A. Milligan, C. Scott Hardaway Jr., George R. Thomas

Reports

The City of Newport News has three public beaches within its limits: Huntington Park beach, Anderson Park beach, and King-Lincoln Park beach. Each beach and its associated park has undergone or is undergoing improvements. The purpose of this report is to assess the rates and patterns of beach change at these three public beaches. Field survey data, aerial photos, wave hindcasting data, and computer modelling were utilized for this report. The computer model used was RCPWAVE, a wave hydrodynamic model developed by the Corps of Engineers.

Current Measurements In The York River Near The Coleman Bridge, John M. Brubaker

Reports

In support of Tidewater Construction Corporation's project to widen the George P. Coleman Bridge, current measurements were conducted in the York River between Gloucester Point and Yorktown, Virginia, along both sides of the bridge. The objective was to sample the currents at approximately 10 feet below the water surface during maximum ebb and flood flow, at enough locations to resolve cross-river variations in the flow field. This objective was well satisfied with multiple surveys conducted during ebb, slack, and flood phases of the tidal flow, each survey providing current data at multiple depths. Significant cross-river variability was documented.

The Virginia Wetlands Report Vol. 10, No. 2, Virginia Institute Of Marine Science

Virginia Wetlands Reports

• Prothonotary Warbler. Julie G. Bradshaw
• Spanish Mackerel. Lyle Varnell
• Sixth Annual Virginia GIS Conference. Marcia Berman
• Washington and Wetlands: Where Do Things Stand? Wetlands and People. Pam Mason
• VIMS and DEQ Water Division Complete Joint Study of Nontidal Wetland Scientific Advisory Needs. Lyle Varnell and Thomas Barnard
• What are nonvegetated wetlands and why are they valuable?

Status Of The Major Oyster Diseases In Virginia 1994 A Summary Of The Annual Monitoring Program, Lisa M. Ragone Calvo, Eugene M. Burreson

Reports

No abstract provided.

Ecotourism: Tripping With Mother Nature, Jill Barnard, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.

Closed Orbit Bifurcations In Continuum Stark Spectra, Michael Courtney, Hong Jiao, Neal Spellmeyer, Daniel Kleppner, J. Gao, John B. Delos

Arts & Sciences Articles

We report an experimental and theoretical study of the effect of bifurcations of closed classical orbits in continuum Stark spectra. Our findings provide a natural way to understand how the spectrum evolves from a simple sinusoidal modulation at positive energy to a quasidiscrete spectrum below the classical ionization limit. The experiment employs scaled-energy spectroscopy of lithium. The results provide the first experimental confirmation of a formulation of closed-orbit theory that provides a quantitative description of the behavior of the spectrum at a bifurcation.

Half-Cycle Pulse Acting On A One-Dimensional Rydberg Atom: Semiclassical Transition Amplitudes In Action And Angle Variables, C. D. Schwieters, John B. Delos

Arts & Sciences Articles

In this paper we derive the expression for the transition coefficient used in the preceding paper [C. D. Schwieters and J. B. Delos, Phys. Rev. A 51, 1023 (1995)] for principal-quantum-number transitions in one-dimensional hydrogen caused by half-cycle pulses. We briefly review the methods of Miller [Adv. Chem. Phys. 25, 69 (1974)] and Marcus [Chem. Phys. Lett. 7, 525 (1970); J. Chem. Phys. 54, 3965 (1971)], and then derive the result using the methods of Maslov and Fedoriuk [Semi-Classical Approximation in Quantum Mechanics, (Reidel, Dordrecht, 1981)]. Also, we examine the approximate reduction of hydrogen …

Semiclassical Treatment Of A Half-Cycle Pulse Acting On A One-Dimensional Rydberg Atom, C. D. Schwieters, John B. Delos

Arts & Sciences Articles

The final-state distribution of hydrogen, acted upon by a 1/2-cycle pulse, has been calculated semiclassically for a proposed one-dimensional experiment. This work was motivated by the recent experimental realization of half-cycle pulses by Jones, You, and Bucksbaum [Phys. Rev. Lett. 70, 1236 (1993)] in which preliminary studies of ionization and state redistribution for hydrogenlike atoms were carried out. To simplify the situation theoretically, an experiment is proposed in which an additional weak static electric field is imposed and approximately one-dimensional states are selected. Within this one-dimensional approximation the transition probability to various n states (n is the principal …

The Virginia Wetlands Report Vol. 10, No. 1, Virginia Institute Of Marine Science

Virginia Wetlands Reports

• Louisiana Waterthrush. Julie G. Bradshaw
• American Eel. Lyle Varnell
• Comprehensive Coastal Inventory Develops New Tidal Wetlands Inventories. Marcia Berman
• Earthwatchers Witness Change in the Chesapeake. Jill Barnard
• Corrotoman River Nature Trail. Pam Mason
• Monkey Bottom Wetland Walkway: A Walk on the Wild Side. Jill Barnard
• Gapped Breakwaters. Walter I. Priest, III
• Why is riprap preferred over bulkheads?
• How do marsh grasses act to stabilize shorelines?

The Primary Source Of Environmental Concern: New Environmental Paradigm Or Presumed Vested Interest Based On Area Of Residence?, Scott Christopher Ramsey

Dissertations, Theses, and Masters Projects

No abstract provided.

Ground Breaking Ceremony For The Marine Chemistry & Toxicology Building, Virginia Institute Of Marine Science, School Of Marine Science, College Of William And Mary

Miscellaneous

Ceremony held April 13, 1995. Program of the event.

Impact Of Artificial Reef Associates On Macrobenthic Community Structure In Florida Bay, Heinz Michael Proft

Dissertations, Theses, and Masters Projects

No abstract provided.

Crassostrea Virginica On Constructed Intertidal Oyster Reefs: The Effects Of Tidal Height And Substrate Level On Settlement, Growth, And Mortality, Ian K. Bartol

Dissertations, Theses, and Masters Projects

No abstract provided.

Occurrence, Fate And Effects Of Polychlorinated Terphenyls In An Estuarine Environment, Kathryn Gallagher

Dissertations, Theses, and Masters Projects

Aroclor 5432, a mixture of polychlorinated terphenyls (PCT), was detected in sediment and several biological compartments including: saltmarsh cordgrass (Spartina alterniflora), American oysters (Crassostrea virginica), red-jointed fiddler crabs (Uca minax), wharf crabs (Sesarma reticulatum) and mummichogs (Fundulus heteroclitus) collected from Tabbs Creek. This tidal creek is located in the southern Chesapeake Bay region. Species from several phyla were selected in order to examine PCT accumulation in physiologically and ecologically different organisms. In general, PCT concentrations in sediment and biota decreased with distance downstream from the PCT outfall. The organism with the highest mean concentration (18,300 &\mu&g/kg dry weight) was the …

Beam Dynamics In The Cebaf Superconducting Cavities, Zenghai Li

Dissertations, Theses, and Masters Projects

This work is a study of beam dynamics in the CEBAF superconducting cavities under the influence of the fields generated by externally applied RF and beam particles.;A full 3-D modeling of the CEBAF 5-cell superconducting cavity is carried out. Details of the modeling with MAFIA are discussed. Multipole fields due to the asymmetric couplers are studied by means of 3-D Fourier transforms. The cavity steering and focusing of the multipole fields are studied. Experimental measurements of these effects are performed to validate the modeling. Evaluation of the cavity misalignment is discussed. The emittance degradation effects in the CEBAF superconducting linacs …

A Comparison Of Three Wetland Evaluation Methods In Their Assessment Of Nontidal Wetlands In The Coastal Plain Of Virginia, Melissa Claire Chaun

Dissertations, Theses, and Masters Projects

No abstract provided.

Ocean Biogeochemical Fluxes - New Production And Export Of Organic-Matter From The Upper Ocean, Hw Ducklow

VIMS Articles

Studies of ocean biogeochemical fluxes have been energized in this decade, by the urgency of our need to understand and predict the effects of continued CO₂accumulation in the atmosphere, by the global perspectives offered by satellite views of ocean color and related physical fields (McClain et al. 1991; Yoder et al. 1992; Mitchell 1994), and by the successful implementation of the Joint Global Ocean Flux Study (JGOFS; Bowles and Livingston, 1993). In this review, I focus on oceanic new production, originally defined as the fraction of primary production supported by inputs of ‘new’ nitrogen from outside the euphotic …

Studies On Processes Controlling The Input Of Agricultural Chemicals In Groundwater To Surface Waters, Edward Laurence Libelo

Dissertations, Theses, and Masters Projects

This dissertation describes several studies of groundwater quality, the fate and transport of nutrients and atrazine in groundwater systems and physical processes at the sediment-water interface which impact on groundwater discharge. Groundwater monitoring wells were installed at the Goodwins Island and Catlett Island NERRS sites in Virginia and agricultural, suburban and forest land use sites in the York and James River Basins. Groundwater was analyzed for nutrients, pH, salinity and trace organics. Shoreline land use, associated nutrient loading and an estimate of total groundwater flux suggest that groundwater contributes up to 30% of the total nitrogen input to the Chesapeake …

Effects Of Simulated Sediment Resuspension Events On The Abundance Of Water Column Bacteria Of Tomales Bay, California, Christopher J. Collumb

Dissertations, Theses, and Masters Projects

No abstract provided.

The Effects Of Hook Type On The Hooking Mortality Of Two Size Classes Of Summer Flounder, Paralichthys Dentatus, Tracy D. Holton

Dissertations, Theses, and Masters Projects

No abstract provided.

A Numerical Model Of The Global Carbon Cycle To Predict Atmospheric Carbon Dioxide Concentrations, Alexis Demitrios Kambis

Dissertations, Theses, and Masters Projects

A numerical model of the global carbon cycle is presented which includes the effects of anthropogenic &CO\sb2& emissions &(CO\sb2& produced from fossil fuel combustion, biomass burning, and deforestation) on the global carbon cycle. The model is validated against measured atmospheric &CO\sb2& concentrations. Future levels of atmospheric &CO\sb2& are then predicted for the following scenarios: (1) Business as Usual (BaU) for the period 1990-2000; (2) Same as (1), but with no biomass burning; (3) Same as (1), but with no fossil fuel combustion; (4) Same as (1), but with a doubled atmospheric &CO\sb2& concentration and a 2 K warmer surface temperature …

The Selective Synthesis Of 3-Alkylidenetetrahydrofurans, Robin Elaine Southward

Dissertations, Theses, and Masters Projects

No abstract provided.

Calcium Carbonate Sedimentation In The Global Ocean: Linkages Between The Neritic And Pelagic Environments, John D. Milliman, Andre W. Droxler

VIMS Articles

Other than fluvial sediment, calcium carbonate (CaCO3) is the greatest source of sediment in the present-day ocean. Interest in carbonate sedimentation extends beyond geologists because the carbonate system involves biologic and geochemical
processes. Carbonate production, for example, releases CO2 but its accumulation becomes a major sink for inorganic carbon.

Unlike fluvial sediments, modern carbonates accumulate more or less equally in the neritic and pelagic environments. Neritic carbonates (benthic) are characterized by rapid production of (mostly) metastable aragonite and magnesian calcite:pelagic production of (primarily) calcite in the open ocean occurs at much slower rates but overmuch larger areas than does neritic …

Resuspension Behavior In The Lower Chesapeake Bay, J.P. -Y Maa, C. -H. Lee

VIMS Books and Book Chapters

Using the VIMS Sea Carousel to conduct in-situ experiments in lower Chesapeake Bay, we found significant spatial a.nd temporal difference of the critical bed shear stress for sediment resuspension, tcr- At the Wolftrap site, tcr varied from 1.1 Pa in the summer to 1.9 Pa in the winter. At the Burwell Bay site, although the bed was too soft for anchoring our research vessel against the changing tide, we identified that tcr was 0.045 Pa. At the Old Plantation site, there was a small amount of fluffy material on top of the bed. At a winter deployment at the Cherrystone …