511 research outputs found

    Plutonium and cesium radionuclides in the Hudson River Estuary. Annual technical progress report, December 1, 1974--November 30, 1975

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    We have obtained a large set of gravity cores from the Hudson Estuary through much of the ambient salinity range. A number of core sections have been analyzed for sup137sup 137Cs, sup134sup 134Cs, sup60sup 60Co, and sup40sup 40K by direct gamma counting, and for sup239sup 239,sup240sup 240Pu by alpha-spectrometry. The distribution of both sup137sup 137Cs and sup239sup 239,sup240sup 240Pu indicates rapid accumulation in marginal cove areas and in the harbor region adjacent to New York City. The distribution of both sup137sup 137Cs and sup239sup 239,sup240sup 240Pu in the sediments is quite similar in surface sediments, and the trends with depth in cores are also similar. The ratio of sediment sup239sup 239,sup240sup 240Pu to sup137sup 137Cs throughout the sampled salinity range (0-20 sup0sup 0/sub00sub 00) approximates that in fallout, except near the nuclear reactor at Indian Point where releases of sup137sup 137Cs result in a ratio lower (0.004 to 0.008) than typical of fallout (0.015). Measurement amounts of reactor-derived sup134sup 134Cs, sup60sup 60Co, and sup54sup 54Mn are found in nearly all of the samples containing appreciable sup137sup 137Cs. These samples were between 15 km upstream of Indian Point reactor site and the downstream extent of our sampling, 70 km south of the reactor. (auth

    A Comparative Study of Public Beliefs about Five Energy Systems

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    Public perceptions (n=244) of five alternative energy sources (nuclear, coal, oil, hydro, and solar) were examined using an attitude model based upon the underlying beliefs held about the attitude object (e.g., each energy system); the focus was on the differing perceptions of sub-groups (n=50) most PRO and CON the use of nuclear energy. Both PRO and CON groups preferred hydro and solar energy to the other energy sources; but the PRO Nuclear Group preferred nuclear energy to the fossil fuels while, for the CON Nuclear Group, nuclear energy was the least preferred system. Of the theoretically possible significant contributors to near-term Austrian electricity supply which were considered in this study (i.e., nuclear, coal, oil), the PRO Nuclear Group saw oil as the alternative to nuclear energy while the CON Nuclear Group preferred coal to oil as the non-nuclear alternative. Factor analysis found that five, relatively independent belief dimensions characterize public thinking about energy systems: beliefs about future-oriented and political risks; economic benefits; environmental risks; psychological/physical risks; and future technology development. Analysis of the belief systems suggested that both PRO and CON Nuclear Groups preferred hydro and solar energy because these systems were perceived as being the least threatening on all risk-related dimensions. The PRO group saw nuclear energy as the system most likely to lead to economic benefits and future technological developments; their low ratings of fossil fuels were primarily due to beliefs that the fossil fuels could provide only marginal economic benefits while leading to appreciable environmental risks. In contrast, the CON group viewed nuclear energy as only marginally more likely to provide economic and technological benefits than the fossil fuels, but as an appreciably greater threat on the risk-related dimensions

    Neuromuscular synaptic function in mice lacking major subsets of gangliosides

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    Gangliosides are a family of sialylated glycosphingolipids enriched in the outer leaflet of neuronal membranes, in particular at synapses. Therefore, they have been hypothesized to play a functional role in synaptic transmission. We have measured in detail the electrophysiological parameters of synaptic transmission at the neuromuscular junction (NMJ) ex vivo of a GD3-synthase knockout mouse, expressing only the O- and a-series gangliosides, as well as of a GM2/GD2-synthase*GD3-synthase double-knockout (dKO) mouse, lacking all gangliosides except GM3. No major synaptic deficits were found in either null-mutant. However, some extra degree of rundown of acetylcholine release at high intensity use was present at the dKO NMJ and a temperature-specific increase in acetylcholine release at 35 °C was observed in GD3-synthase knockout NMJs, compared with wild-type. These results indicate that synaptic transmission at the NMJ is not crucially dependent on the particular presence of most ganglioside family members and remains largely intact in the sole presence of GM3 ganglioside. Rather, presynaptic gangliosides appear to play a modulating role in temperature- and use-dependent fine-tuning of transmitter output

    Role of Sterile Neutrino Warm Dark Matter in Rhenium and Tritium Beta Decays

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    Sterile neutrinos with mass in the range of one to a few keV are important as extensions of the Standard Model of particle physics and are serious dark matter (DM) candidates. This DM mass scale (warm DM) is in agreement with both cosmological and galactic observations. We study the role of a keV sterile neutrino through its mixing with a light active neutrino in Rhenium 187 and Tritium beta decays. We pinpoint the energy spectrum of the beta particle, 0 < T_e < (Q_{beta} - m_s), as the region where a sterile neutrino could be detected and where its mass m_s could be measured. This energy region is at least 1 keV away rom the region suitable to measure the mass of the light active neutrino, located near the endpoint Q_{beta} . The emission of a keV sterile neutrino in a beta decay could show up as a small kink in the spectrum of the emitted beta particle. With this in view, we perform a careful calculation of the Rhenium and Tritium beta spectra and estimate the size of this perturbation by means of the dimensionless ratio R of the sterile neutrino to the active neutrino contributions. We comment on the possibility of searching for sterile neutrino signatures in two experiments which are currently running at present, MARE and KATRIN, focused on the Rhenium 187 and Tritium beta decays respectively.Comment: 16 pages, 10 figures. Version to appear in Nucl. Phys. B. Results and conclusions unchange

    Neolithic settlement at the woodland's edge: palynological data and timber architecture in Orkney, Scotland

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    It has often been assumed that the islands of Orkney were essentially treeless throughout much of the Holocene, with any ‘scrub’ woodland having been destroyed by Neolithic farming communities by around 3500 cal. BC. This apparently open, hyper-oceanic environment would presumably have provided quite marginal conditions for human settlement, yet Neolithic communities flourished and the islands contain some of the most spectacular remains of this period in north-west Europe. The study of new Orcadian pollen sequences, in conjunction with the synthesis of existing data, indicates that the timing of woodland decline was not synchronous across the archipelago, beginning in the Mesolithic, and that in some areas woodland persisted into the Bronze Age. There is also evidence to suggest that woodland communities in Orkney were more diverse, and therefore that a wider range of resources was available to Neolithic people, than has previously been assumed. Recent archaeological investigations have revealed evidence for timber buildings at early Neolithic settlement sites, suggesting that the predominance of stone architecture in Neolithic Orkney may not have been due to a lack of timber as has been supposed. Rather than simply reflecting adaptation to resource constraints, the reasons behind the shift from timber to stone construction are more complex and encompass social, cultural and environmental factors

    A re-examination of the life and work of A.F.G. Kerr and of his colleagues and friends

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    Arthur Francis George Kerr’s life is reviewed and related to a previously published account. Kerr’s collecting activity is analysed using an expanded version of the Thai Biogeography Group’s database of collections. 8,666 of the total 48,970 collections are Kerr’s and 3,178 are those of his colleagues and friends. Therefore, the total number of collections made by Kerr and his acquaintances is likely to be larger and more diverse than previously believed. Mapping of these data using GIS show that Kerr’s collecting activities focussed on particular regions of Thailand at particular times. Also large areas of the country remained unexplored by Kerr and his acquaintances: a pattern that, to some extent, persists to this day. The large, but dispersed, archive of Kerr’s photographs, maps, living collections and correspondence indicate that he was a skilled photographer (taking at least 3,000 images), cartographer (producing many hand-drawn maps) and exceptionally acute, accurate and detailed observer (filling numerous notebooks and leaving other records). It is clear that digitising these collections to form an on-line dedicated website is highly desirable to further progress on the flora of Thailand and surrounding countries and would form an unique record of the social history of early 20thC Thailand

    Looking forward through the past: identification of 50 priority research questions in palaeoecology

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    1. Priority question exercises are becoming an increasingly common tool to frame future agendas in conservation and ecological science. They are an effective way to identify research foci that advance the field and that also have high policy and conservation relevance. 2. To date, there has been no coherent synthesis of key questions and priority research areas for palaeoecology, which combines biological, geochemical and molecular techniques in order to reconstruct past ecological and environmental systems on time-scales from decades to millions of years. 3. We adapted a well-established methodology to identify 50 priority research questions in palaeoecology. Using a set of criteria designed to identify realistic and achievable research goals, we selected questions from a pool submitted by the international palaeoecology research community and relevant policy practitioners. 4. The integration of online participation, both before and during the workshop, increased international engagement in question selection. 5. The questions selected are structured around six themes: human–environment interactions in the Anthropocene; biodiversity, conservation and novel ecosystems; biodiversity over long time-scales; ecosystem processes and biogeochemical cycling; comparing, combining and synthesizing information from multiple records; and new developments in palaeoecology. 6. Future opportunities in palaeoecology are related to improved incorporation of uncertainty into reconstructions, an enhanced understanding of ecological and evolutionary dynamics and processes and the continued application of long-term data for better-informed landscape management

    'The brede of good & strong Horsis': zooarchaeological evidence for size change in horses from early modern London

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    Almost 200 horse bone measurements from 38 sites excavated across the city of London, dating to the period AD 1220–1900 were analysed. Results identified three main phases of size change: a reduction in size in the mid 14th to 15th century, and size increases in the mid 15th to 16th century and the 17th century. The decline in size testifies to the disruption of horse breeding in the wake of the Black Death, whilst the increases reflect purposeful attempts to increase the size of horses in England through a combination of regulated breeding and the importation of new bloodlines
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