Physical Sciences and Mathematics Commons^™

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 …

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.

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

Reports

No abstract provided.

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 …

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.

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.

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.

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.

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 …

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 …

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.

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 …

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 …

Modeling Cumulative Impacts And The Carrying Capacity Of Small Tidal Creeks And Inlets, Bruce J. Neilson, Carl H. Hershner, Megan K. Greiner

Reports

The purpose of this project was to identify pollutant loading values which might be used as input for a series of water quality models applied to small tidal creeks and inlets in Virginia's coastal plain. The intent was to identify values from literature sources which might be used in application of the models, absent better or more site specific information. Estimates of biological oxygen demand, chemical oxygen demand and fecal coliform loadings were of specific interest.

Field Study Of Currents At Norfolk Naval Shipyard, Portsmouth, Virginia, John M. Brubaker

Reports

As a component of an investigation into biofouling problems near the Norfolk Naval Shipyard, a field study of currents was conducted in the Southern Branch of the Elizabeth River in the vicinity of the shipyard's aircraft carrier slips. The objective of this study was to determine the magnitude and direction of currents in an area encompassing the turning basin adjacent to the slips, and the transitional regions to the north and south where the river tapers from a width of approximately 600 m in the turning basin to its more typical width of 150 m. To the north, the transition …

Management Plan For Sea Turtles And Marine Mammals In Virginia, The Virginia Sea Turtle/Marine Mammal Conservation Team

Reports

No abstract provided.

A Three-Dimensional Hydrodynamic-Eutrophication Model (Hem-3d) : Description Of Water Quality And Sediment Process Submodels, Kyeong Park, Albert Y. Kuo, Jian Shen, John M. Hamrick

Reports

Virginia Institute of Marine Science (VIMS) has been developing a general purpose three-dimensional hydrodynamic and sediment transport model, Environmental Fluid Dynamics Computer Code (EFDC; Hamrick 1992). The real-time model simulates density and topographically-induced circulation as well as tidal and wind-driven flows, and spatial and temporal distributions of salinity, temperature and sediment concentration. The model also is capable of handling the wetting and drying of shallow area, hydraulic control structures, vegetation resistance for wetlands and Lagrangian particle tracking. The information of physical transport processes, both advective and diffusive, simulated by the hydrodynamic model can be used to account for the transport …

Regulating The Blue Crab, Callinectes Sapidus, Fishery In Virginia : Biological And Economic Concerns, James E. Kirkley, William D. Dupaul, Michael J. Oesterling

Reports

The blue crab, Callinectes sapiclus, fishery has been one of the most important fisheries of Virginia. The importance of the fishery in terms of commercial activities has substantially increased in recent years in response to declining resource levels of American Oyster, Crassostrea virginica, and a growing international and domestic demand for soft crabs, female hard crabs, and crab meat.

The actual economic importance of the fishery, however, is not well known. For example, what are the employment and earning levels generated by the fishery? What portion of a waterman's household income is derived from crabbing? How much does crabbing contribute …

Directional Wave Observations, Thimble Shoal Light, September 19, 1994 To March 13, 1995, John D. Boon

Reports

The Virginia Institute of Marine Science, in cooperation with the Virginia Department of Conservation and Recreation, Division of Soil and Water conservation, has identified as one of its major goals the systematic study of hydrodynamic processes that affect recreational, shoreline and benthic resources in the coastal zone of the Commonwealth. As one component of the Virginia Coastal Information Program, a wave climatology project was initiated in 1988 with support from the National Oceanographic and Atmospheric Agency's Coastal Zone Management Program administered by the Virginia Council on the Environment. Directional wave observations were begun on a seasonal schedule (fall, winter, spring) …

Stafford County Shoreline Protection Report, Potomac River, Aquia Creek : Prepared For County Of Stafford, Department Of Planning And Community Development, Vhb : Vanasse, Hangen And Brustlin, Inc., Virginia Institute Of Marine Science

Reports

No abstract provided.

Water Resources : Planning For Future Demand In The York River Basin, Mel Vargas, Carl Hershner, Marcia Berman

Reports

This report analyzes issues related to water supply and demand for the York River Basin (YRB) in Virginia.

Azidotetrakis(Trimethylphosphine)Nickel(Ii) Tetrafluoroborate, Caryn C. Carson, Robert D. Pike

Arts & Sciences Articles

The title complex, [Ni(N3)(C3H9P)4]BF4, is a nearly perfect trigonal bipyramid with the azide group at an apical position. The metal-azide bond angle, Nil-- NlmN2, of 138.6(5) ° is the largest observed for a terminal azide ligand.

Critical Elements In The Application Of Water Quality Standards To Wetlands : Classification System, Beneficial Use Designation And The Identification Of Exceptional Wetlands, Pamela A. Mason, Carl H. Hershner, Virginia Institute Of Marine Science. Department Of Resource Management And Policy, Wetlands Program

Reports

No abstract provided.

Investigation And Long-Term Monitoring Of Phragmites Australis Within Virginia's Constructed Wetland Sites : Final Report, Kirk J. Havens, Walter I. Priest Iii, Harry Berquist

Reports

The use of constructed wetlands to replace natural wetlands is becoming pandemic. An investigation using Global Positioning System technology to map the vegetated communities of fifteen of the largest constructed wetlands in Virginia reveals that 80% are colonized by the invasive species, Phragmites australis Trin., and/or aggressive species, Typha spp. Tidally influenced wetlands that have subtidal perimeter ditches have significantly less (p<0.05) P. australis in the wetland interior than those without perimeter ditches. Fractured regression analyses show that 6-years after constructionP. australis invasion can be extensive. Linear regression analysis suggests that, if conditions remain favorable for P. australis colonization, constructed wetlands could be overrun in 40 years.

On The Minimum Of Independent Geometrically Distributed Random Variables, Gianfranco Ciardo, Lawrence Leemis, David Nicol

Arts & Sciences Articles

The expectations E[X(1)], E[Z(1)], and E[Y(1)] of the minimum of n independent geometric, modified geometric, or exponential random variables with matching expectations differ. We show how this is accounted for by stochastic variability and how E[X(1)]/E[Y(1)] equals the expected number of ties at the minimum for the geometric random variables. We then introduce the “shifted geometric distribution”, and show that there is a unique value of the shift for which the individual shifted geometric and exponential random variables match expectations both individually and in …