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The Outer Banks barrier islands of North Carolina, USA, contain a geologic record of inlet activity that extends from ca. 2200 cal yr BP to the present, and can be used as a proxy for storm activity. Optically stimulated luminescence (OSL) dating (26 samples) of inlet-fill and flood tide delta deposits, recognized in cores and geophysical data, provides the basis for understanding the chronology of storm impacts and comparison to other paleoclimate proxy data. OSL ages of historical inlet fill compare favorably to historical documentation of inlet activity, providing confidence in the technique. Comparison suggests that the Medieval Warm Period (MWP) and Little Ice Age (LIA) were both characterized by elevated storm conditions as indicated by much greater inlet activity relative to today. Given present understanding of atmospheric circulation patterns and sea-surface temperatures during the MWP and LIA, we suggest that increased inlet activity during the MWP responded to intensified hurricane impacts, while elevated inlet activity during the LIA was in response to increased nor'easter activity. A general decrease in storminess at mid-latitudes in the North Atlantic over the last 300 yr has allowed the system to evolve into a more continuous barrier with few inlets.
A detailed record of late Quaternary sea-level oscillations is preserved within the upper 45 m of deposits along an eight km transect across Croatan Sound, a drowned tributary of the Roanoke/Albemarle drainage system, northeastern North Carolina. Drill-hole and seismic data reveal nine relatively complete sequences filling an antecedent valley comprised of discontinuous middle and early Pleistocene deposits. On interfluves, lithologically similar marine deposits of different sequences occur stacked in vertical succession and separated by ravinement surfaces. Within the paleo-drainage, marine deposits are separated by fluvial and/or estuarine sediments deposited during periods of lowered sea level. Foraminiferal and molluscan fossil assemblages indicate that marine facies were deposited in a shallow-marine embayment with open connection to shelf waters. Each sequence modifies or truncates portions of the preceding sequence or sequences. Sequence boundaries are the product of a combination of fluvial, estuarine, and marine erosional processes. Stratigraphic and age analyses constrain the ages of sequences to late Marine Isotope Stage (MIS) 6 and younger (∼ 140 ka to present), indicating multiple sea-level oscillations during this interval. Elevations of highstand deposits associated with late MIS 5 and MIS 3 imply that sea level was either similar to present during those times, or that the region may have been influenced by glacio-isostatic uplift and subsidence.
Foraminiferal analyses of 404 contiguous samples, supported by diatom, lithologic, geochronologic and seismic data, reveal both rapid and gradual Holocene paleoenvironmental changes in an 8.21-m vibracore taken from southern Pamlico Sound, North Carolina. Data record initial flooding of a latest Pleistocene river drainage and the formation of an estuary 9000 yr ago. Estuarine conditions were punctuated by two intervals of marine influence from approximately 4100 to 3700 and 1150 to 500 cal yr BP. Foraminiferal assemblages in the muddy sand facies that accumulated during these intervals contain many well-preserved benthic foraminiferal species, which occur today in open marine settings as deep as the mid shelf, and significant numbers of well-preserved planktonic foraminifera, some typical of Gulf Stream waters. We postulate that these marine-influenced units resulted from temporary destruction of the southern Outer Banks barrier islands by hurricanes. The second increase in marine influence is coeval with increased rate of sea-level rise and a peak in Atlantic tropical cyclone activity during the Medieval Climate Anomaly. This high-resolution analysis demonstrates the range of environmental variability and the rapidity of coastal change that can result from the interplay of changing climate, sea level and geomorphology in an estuarine setting.
For the first time, electron spin resonance optical dating (ESROD) has been conducted on littorally transported and aeolian siliciclastic sediments in Florida. ESROD utilizes light-sensitive radiation-sensitive defects at silicon sites that have been replaced by aluminum and titanium atoms to give rise to a time-dependant signal. These defects saturate at higher levels of radiation dose, compared to optically stimulated luminescence, and therefore extend the optical dating range back into the millions of years. Our results show that the Trail Ridge Sequence is a multi-depositional unit that began deposition around 2.2 Ma and continued until 6 ka. The Osceola Cape, of the Effingham Sequence, was deposited around 1.5 Ma, and the Chatham Sequence was a multi-depositional terrace with at least three events preserved.
Marc L. Turner, Professor of Cellular Therapy, University of Edinburgh; Clinical Director/Consultant Haematologist, Edinburgh and S.E. Scotland Blood Transfusion Centre, Royal Infirmary of Edinburgh, Edinburgh, Scotland,
Patricia E. Hewitt, Consultant Specialist in Transfusion Microbiology, NHS Blood and Transplant Colindale, London, UK,
Moira Bruce, Institute for Animal Health Neuropathogenesis Unit, Edinburgh, UK,
James W. Ironside, Professor of Clinical Neuropathology, National CJD Surveillance Unit, University of Edinburgh, Western General Hospital, Edinburgh, UK,
David J. Anstee, Bristol Institute for Transfusion Sciences, NHS Blood and Transplant, Bristol, UK,
Gary Mallinson, Bristol Institute for Transfusion Sciences, NHS Blood and Transplant, Bristol, UK
Prion diseases include a spectrum of disorders in animals and man (see Table 9.1). Scrapie, endemic in sheep and goat populations throughout most of the world, was first recognized over 250 years ago and was demonstrated to be experimentally transmissible in 1936. Chronic wasting disease (CWD) is endemic in Rocky Mountain elk, white-tailed deer and mule deer in several areas of the USA and is increasing in both incidence and geographic distribution. The routes by which these two endemic prion diseases are transmitted remain unclear. Transmissible mink encephalopathy was first recorded to have occurred in 1947 in farmed mink in Wisconsin and was probably transmitted through prion infected food.
Bovine spongiform encephalopathy (BSE) was first recognized in the UK in 1985/86 (Wells et al., 1987). Affected cattle become apprehensive, hypersensitive, ataxic and generally difficult to handle, giving rise to the common name of mad cow disease. It remains unclear whether BSE arose spontaneously in cattle or resulted from transmission of scrapie from sheep, but onward transmission is thought to have occurred through the practice of feeding cattle ruminant-derived meat and bone meal. Over 180,000 clinical cases of BSE have been reported in the UK since 1985, though the annual incidence has now fallen to just over 100 cases per annum. Over 4500 infected cattle have been detected elsewhere, mainly in Europe, the majority associated with the export of BSE infected cattle or meat and bone meal from the UK. It is estimated that between 1 and 2 million cattle may have become infected and entered the human food chain before developing evidence of clinical disease (Donnelly et al. 2002).
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