532 research outputs found

    The Cypress Coaxial Backbone Packet Switch

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    The Tiger Quick Step

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    Validation of an ion selective electrode system for the analysis of serum fluoride ion

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    A high impedance unit was developed for use with a fluoride/pH electrode system for the measurement of serum fluoride. The linearity, accuracy, precision and detection limit of the system is reported. At a pH of 1.55, the system was linear over a range of serum fluoride concentrations up to 100 μmol l-1, with a lower limit of detection of 0.3 μmol l-1. Recoveries at this pH were 94-105% in the range 2.6-100 μmol l-1. Within-run CVs ranged from 4.2% at a level of 2.3 μmol l-1 to 1.2% at a level of 55.7 μmol l-1, while day-to-day CVs ranged from 12.8% at a level of 2.2 μmol l-1 to 4.6% at a level of 51.7 μmol l-1. The system demonstrated a rapid response time and has the potential for a smaller sample size requirement with alternative electrode shape. Continued development of this unit into an automated fluoride ion selective electrode system is recommended, since the measurement of serial serum fluoride samples is of greatest importance in assessing the impact of new anaesthetic agents on renal function

    Ehrlichia chaffeensis Infections among HIV-infected Patients in Human Monocytic Ehrlichiosis–Endemic Area

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    Manifestations of human monocytic ehrlichiosis (HME), a tick-borne infection caused by Ehrlichia chaffeensis, range from asymptomatic disease to fulminant infection and may be particularly severe in persons infected with HIV. We conducted a serologic study to determine the epidemiology of HME in HIV-positive patients residing in an HME-endemic area. We reviewed charts from a cohort of 133 HIV-positive patients who were seen during the 1999 tick season with symptoms compatible with HME (n=36) or who were asymptomatic (n=97). When available, paired plasma samples obtained before and after the tick season were tested by using an indirect immunofluorescence assay (IFA) to detect antibodies reactive to E. chaffeensis. Two symptomatic incident cases were identified by IFA, resulting in a seroincidence of 6.67% among symptomatic HIV-positive participants with paired samples available for testing and 1.64% overall. The baseline seroprevalence of HME was 0%. In contrast to infection in immunocompetent patients, E. chaffeensis infection in HIV-positive persons typically causes symptomatic disease

    Shoreline Evolution Chesapeake Bay Shoreline Northampton County, VA

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    Shoreline evolution is the change in shore position through time. In fact, it is the material resistance of the coastal geologic underpinnings against the impinging hydrodynamic (and aerodynamic) forces. Along the shores of the Chesapeake Bay, it is a process-based response system. The processes at work include winds, waves, tides, and currents, which together provide the energy which shapes and modifies coastlines by eroding, transporting, and depositing sediments. The shore line is commonly plotted and measured to provide a rate of change, but it is as important to understand the geomorphic patterns of change. Shore analysis provides the basis to know how a particular coast has changed through time and how it may proceed in the future. The purpose of this report is to document how the Bay shore of Northampton County, Virginia (Figure 1) has evolved since 1938. Aerial imagery was taken for most of the Bay region beginning that year, and it is this imagery that allows one to assess the geomorphic nature of shore change. Aerial imagery shows how the nature of the coast has changed, how beaches, dunes, bars, and spits have grown or decayed, how barriers have breached, how inlets have changed course, and how one shore type has displaced another or has not changed at all. Shore change is a natural process but, quite often, the impacts of man through shore hardening or inlet stabilization come to dominate a given shore reach. Most of the shore positions will be quantified in this report. Others, particularly very irregular coasts, around inlets, and other areas will be subject to interpretation

    Chesapeake Bay Dune Systems: Monitoring

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    This project is aimed at developing an understanding of detailed beach and dune change. During the course of this monitoring, Hurricane Isabel impacted the coastal plain of Virginia and significantly altered almost all Bay shorelines to one degree or another in September 2003. This is particularly true of shorelines facing north, east, and south since the winds shifted as the storm passed. This event provided an opportunity to measure the changes to natural dune systems around the Bay due to the storm as well as their recovery after the event

    Shoreline evolution, Chesapeake Bay shoreline, City of Virginia Beach, Virginia

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    Shoreline evolution is the change in shore position through time. In fact, it is the material resistance of the coastal geologic underpinnings against the impinging hydrodynamic (and aerodynamic) forces. Along the shores of Chesapeake Bay, it is a process-response system. The processes at work include winds, waves, tides and currents, which shape and modify coastlines by eroding, transporting and depositing sediments. The shore line is commonly plotted and measured to provide a rate of change but it is as important to understand the geomorphic patterns of change. Shore analysis provides the basis to know how a particular coast has changed through time and how it might proceed in the future. The purpose of this report is to document how the Bay shore of Virginia Beach (Figure 1) has evolved since 1937. Aerial imagery was taken for most of the Bay region beginning that year, and it is this imagery that allows one to assess the geomorphic nature of shore change. Aerial imagery shows how the nature of the coast has changed, how beaches, dunes, bars, and spits have grown or decayed, how barriers have breached, how inlets have changed course, and how one shore type has displaced another or has not changed at all. Shore change is a natural process but, quite often, the impacts of man through shore hardening or inlet stabilization come to dominate a given shore reach. Most of the change in shore positions will be quantified in this report. Others, particularly very irregular coasts, around inlets, and other areas will be subject to interpretation

    Shoreline Evolution Chesapeake Bay Shoreline City of Norfolk, VA

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    Shoreline evolution is the change in shore position through time. In fact, it is the material resistance of the coastal geologic underpinnings against the impinging hydrodynamic (and aerodynamic) forces. Along the shores of Chesapeake Bay, it is a process-response system. The processes at work include winds, waves, tides and currents, which together shape and modify coastlines by eroding, transporting and depositing sediments. The shore line is commonly plotted and measured to provide a rate of change, but it is as important to understand the geomorphic patterns of change. Shore analysis provides the basis to know how a particular coast has changed through time and how it might proceed in the future. The purpose of this report is to document how the Chesapeake Bay shore of Norfolk (Figure 1) has evolved since 1937. This is the first year that aerial imagery was taken for most of the Bay region, and it is this imagery that allows one to assess the geomorphic nature of shore change. Aerial imagery shows how the nature of the coast has changed, how beaches, dunes, bars and spits have grown or decayed, how barriers have breached, how inlets have changed course and how one shore type has displaced another or has not changed at all. Shore change is a natural process but, quite often, the impacts of man through shore hardening, beach nourishment or inlet stabilization will come to dominate a given shore reach. Most of the change in shore positions will be quantified in this report. Others, particularly around inlets and very irregular coasts, will be interpreted

    The Chesapeake Bay Breakwater Database Project Hurricane Isabel Impacts to Four Breakwater Systems

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    The Chesapeake Bay Breakwater Database is being developed by personnel in the Virginia Institute of Marine Science’s (VIMS) Shoreline Studies Program for the U.S. Army Corps of Engineers (COE) in order to: 1) document breakwater system performance around Chesapeake Bay relative to predictions 2) develop guidelines for breakwaters in sand limited and fetch limited systems such as estuaries, reservoirs, lakes and bays
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