Complex inner shelf environments: Observations and modeling of morphodynamics and scour processes

The inner continental shelf is a complex environmental system marked by sharp variations in bed roughness. Such heterogeneous systems account for 80% of the non-rocky inner shelves worldwide. Interactions among forces (waves, tides, turbulence, and bioturbation) and roughness elements (bed forms, rocks, and anthropogenic objects) exert major controls on sedimentary processes. This study attempts to advance the knowledge and understanding of the morphodynamics of the inner shelf. This study investigates scour and morphodynamic processes at Tairua, New Zealand; Cedar Island, Virginia; Indian Rocks Beach, Florida; and Beaufort Inlet, North Carolina. Using data from the field, the study develops new conceptual models to characterize and quantify the hydrodynamics and morphology of the seabed. The overall dataset includes side-scan sonograms, sub-bottom profiles, grain-size analyses, suspended sediment concentrations and hydrodynamic measurements. Analysis of the morphological data yielded a six-type classification of bottom features previously termed Rippled Scour Depressions (RSDs). The observed stratigraphic signature of RSDs does not agree with the previous interpretation of their formation. Striking spatial and temporal variations in seabed roughness produce significant enhancements of hydraulic roughness and turbulence over different substrates resulting in a self-organized, feed-back system of erosion (scour), deposition, and modified bed forms. The study demonstrates that widely used ripple models inadequately predict bed form geometry and behavior, especially during storms. Improved understanding of scour processes developed in this study leads to a new model of scour and burial of sea-bed objects such as naval mines and archaeological artifacts. When using the model to predict scour and burial, the greatest errors result from the uncertainties in the available forecasts of wave conditions. The model includes vertical variations in sediment characteristics as field observations indicate abrupt changes in substrate substantially alter the scour process. The overall study makes substantial contributions to the general understanding of RSD behavior by tying together detailed field studies with applicable insights from the area of complexity research. A new conceptual model of complex phase-transition is developed, involving critical process factors (hydrodynamics, underlying geology, and depth), which contribute to the observed spatial complexity and temporal variability of different RSD types

They opened the door too late : African Americans and baseball, 1900-1947

During Jim Crow, the sport of baseball served as an important arena for African American resistance and negotiation. as a (mostly) black enterprise, the Negro Leagues functioned as part of a larger African American movement to establish black commercial ventures during segregation. Moreover, baseball\u27s special status as the national pastime made it a significant public symbol for African American campaigns for integration and civil rights.;This dissertation attempts to interrogate the experience and significance of black baseball during Jim Crow during the first half of the twentieth century. Relying on newspapers, magazines, memoirs, biographies, and previously published oral interviews, this work looks at resistance and political critique that existed in the world of black sport, particularly in the cultural production of black baseball.;Specifically, this dissertation argues that in a number of public and semi-public arenas, African Americans used baseball as a literal and figurative space in which they could express dissatisfaction with the strictures of Jim Crow as well as the larger societal understanding of race during the early twentieth century. African Americans asserted a counter-narrative of black racial equality and superiority through their use of physical space in ballparks and on the road during travel, through the public negotiation of black manhood on the pages of the black press, through the editorial art and photography of black periodicals, and through the employment of folktales and nicknames.;The African American experience during Jim Crow baseball and the attendant social and cultural production provide a window into the subtle and unstated black resistance to white supremacy and scientific racism. Thus this dissertation explores and identifies the political meanings of black baseball

Filming Eugenics: Teaching the History of Eugenics Through Film

In teaching eugenics to undergraduate students and general public audiences, film should be considered as a provocative and fruitful medium that can generate important discussions about the intersections among eugenics, gender, class, race, and sexuality. This paper considers the use of two films, A Bill of Divorcement and The Lynchburg Story, as pedagogical tools for the history of eugenics. The authors provide background information on the films and suggestions for using the films to foster an active engagement with the historical eugenics movement

Modular Autonomous Biosampler (MAB)- A prototype system for distinct biological size-class sampling and preservation

Presently, there is a community wide deficiency in our ability to collect and preserve multiple size-class biologic samples across a broad spectrum of oceanographic platforms (e.g. AUVs, ROVs, and Ocean Observing System Nodes). This is particularly surprising in comparison to the level of instrumentation that now exists for acquiring physical and geophysical data (e.g. side-scan sonar, current profiles etc.), from these same platforms. We present our effort to develop a low-cost, high sample capacity modular,autonomous biological sampling device (MAB). The unit is designed for filtering and preserving 3 distinct biological size-classes (including bacteria), and is deployable in any aquatic setting from a variety of platform modalities (AUV, ROV, or mooring)

Correction of Bathymetric Survey Artifacts Resulting from Apparent Wave-Induced Vertical Position of an AUV

Recent increases in the capability and reliability of autonomous underwater vehicles (AUVs) have provided the opportunity to conduct bathymetric seafloor surveys in shallow water (\u3c 50 m). Unfortunately, surveys of this water depth may contain artifacts induced by large amplitude wave motion at the surface. The artifacts occur when an onboard pressure sensor determines the depth of the AUV. Waves overhead induce small pressure fluctuations at depth, which modulate the AUV’s pressure sensor output without causing actual vertical movement of the AUV. Since bathymetric measurements are made with respect to the AUV’s depth, these pressure fluctuations, in turn, modulate the measurement of the seafloor. The result is a periodic across-track, vertical offset of the seafloor profile (similar to a heave artifact sometimes common in surface vessel surveys). In this paper we describe our experience with the “Gavia” model AUV (Hafmynd EHF, Iceland) in a recent bathymetric survey during which wave action overhead induced such an artifact with a peak-to-peak amplitude as large as 1 meter. A method for removing the artifact as well as recommendations for modifications to the sonar, INS and AUV to mitigate the effect in the future are provided

Charles C. Green v. County School Board of New Kent County, U.S. Supreme Court decision

Lesson plan and historical background for the 1968 Charles C. Green et al., v, County School board of New Kent County, Virginia, et al (391 U.S. 430) Supreme Court decision which defined the standards by which federal courts would judge whether a violation of U.S. constitution existed in school desegregation cases

Designing Improved Sediment Transport Visualizations

Monitoring, or more commonly, modeling of sediment transport in the coastal environment is a critical task with relevance to coastline stability, beach erosion, tracking environmental contaminants, and safety of navigation. Increased intensity and regularity of storms such as Superstorm Sandy heighten the importance of our understanding of sediment transport processes. A weakness of current modeling capabilities is the ability to easily visualize the result in an intuitive manner. Many of the available visualization software packages display only a single variable at once, usually as a two-dimensional, plan-view cross-section. With such limited display capabilities, sophisticated 3D models are undermined in both the interpretation of results and dissemination of information to the public. Here we explore a subset of existing modeling capabilities (specifically, modeling scour around man-made structures) and visualization solutions, examine their shortcomings and present a design for a 4D visualization for sediment transport studies that is based on perceptually-focused data visualization research and recent and ongoing developments in multivariate displays. Vector and scalar fields are co-displayed, yet kept independently identifiable utilizing human perception\u27s separation of color, texture, and motion. Bathymetry, sediment grain-size distribution, and forcing hydrodynamics are a subset of the variables investigated for simultaneous representation. Direct interaction with field data is tested to support rapid validation of sediment transport model results. Our goal is a tight integration of both simulated data and real world observations to support analysis and simulation of the impact of major sediment transport events such as hurricanes. We unite modeled results and field observations within a geodatabase designed as an application schema of the Arc Marine Data Model. Our real-world focus is on the Redbird Artificial Reef Site, roughly 18 nautical miles offshor- Delaware Bay, Delaware, where repeated surveys have identified active scour and bedform migration in 27 m water depth amongst the more than 900 deliberately sunken subway cars and vessels. Coincidently collected high-resolution multibeam bathymetry, backscatter, and side-scan sonar data from surface and autonomous underwater vehicle (AUV) systems along with complementary sub-bottom, grab sample, bottom imagery, and wave and current (via ADCP) datasets provide the basis for analysis. This site is particularly attractive due to overlap with the Delaware Bay Operational Forecast System (DBOFS), a model that provides historical and forecast oceanographic data that can be tested in hindcast against significant changes observed at the site during Superstorm Sandy and in predicting future changes through small-scale modeling around the individual reef objects

A Study to Assess the Effect of Tow Duration and Estimate Dredge Efficiency for the VIMS Sea Scallop Dredge Survey : Final Report

For the sea scallop, Placopecten magellanicus, the concepts of space and time have emerged as the basis of an effective management tool. The strategy of closing or limiting activities in certain areas for specific lengths of time has gained support as a method to conserve and enhance the sea scallop resource. In the last decade, rotational area management has provided a mechanism to protect juvenile scallops from fishing mortality by closing areas based upon scallop abundance and age distribution. Approximately half of the sea scallop industry’s current annual landings come from areas under this rotational harvest strategy. While this represents a management success, it also highlights the extent to which landings are dependent on the success of this strategy. The continued prosperity of scallop spatial management is dependent on both periodic and large incoming year classes, as well as, a mechanism to delineate the scale of a recruitment event and subsequently monitor the growth and abundance of these scallops over time. Current and accurate information related to the abundance and distribution of adult and juvenile scallops is essential for managers to respond to changes in resource subunits

Estimates Of Sea Scallop (Placopecten Magellanicus) Incidental Mortality From Photographic Multiple Before-After-Control-Impact Surveys

After several decades of stock decline, the Atlantic sea scallop ( Placopecten magellanicus) resource has rebounded to become one of the most valuable fisheries in the United States. The continued sustainability of this fishery is supported by catch limits determined by annual stock projection models. Incidental mortality is an important term in these projection models, but is historically difficult to measure. Current estimates are derived from field experiments that relied heavily on qualitative observations and as a result are based on limited data with low precision. To better quantify incidental mortality, a multiple before-after-control-impact experimental design was used to measure the effect of scallop dredging on the disposition of sea scallops that remain uncaptured on the seafloor following dredging. An autonomous underwater vehicle was used to collect color photographs and side-scan sonar images of the seafloor before and after controlled dredge treatments in the mid-Atlantic and Georges Bank regions. Approximately 170,000 photographs were annotated for instances of mortality. Dredge-induced incidental mortality of 2.5% and 8% was estimated for the mid-Atlantic Bight and Georges Bank sites, respectively, a difference that is likely attributable to the relatively harder substrate of the scallop habitat on Georges Bank that results in greater physical trauma to the uncaptured scallops. This study provides a quantitative estimate of incidental mortality using a noninvasive platform that offers precise mission navigation for repeated surveys. The spatial scale and distribution of the study sites are broad relative to past incidental mortality studies, and the substrate types at each are common in the sea scallop fishery. Estimated mortality rates are lower than the values currently used in fishery stock models and suggest the existing values are conservative, but likely appropriate estimates for management purposes