17 research outputs found

    Processing Techniques of MOS Capacitors

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    Variations in both MOS capacitor structure and fabrication process were characterized using 1MHz C-V measurements. This involved processing MOS capacitors with and without backside oxide, and wet etching versus plasma ashing photoresist. The experimental results show large flatband shifts in wafers that were plasma ashed. ~ longer than expected anneal was utilized to reduce the C-V shifts caused by positive charge build-up in the oxide. The backside oxide did not grossly affect the capacitance measurements

    Delivery of Dark Material to Vesta via Carbonaceous Chondritic Impacts

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    NASA's Dawn spacecraft observations of asteroid (4) Vesta reveal a surface with the highest albedo and color variation of any asteroid we have observed so far. Terrains rich in low albedo dark material (DM) have been identified using Dawn Framing Camera (FC) 0.75 {\mu}m filter images in several geologic settings: associated with impact craters (in the ejecta blanket material and/or on the crater walls and rims); as flow-like deposits or rays commonly associated with topographic highs; and as dark spots (likely secondary impacts) nearby impact craters. This DM could be a relic of ancient volcanic activity or exogenic in origin. We report that the majority of the spectra of DM are similar to carbonaceous chondrite meteorites mixed with materials indigenous to Vesta. Using high-resolution seven color images we compared DM color properties (albedo, band depth) with laboratory measurements of possible analog materials. Band depth and albedo of DM are identical to those of carbonaceous chondrite xenolith-rich howardite Mt. Pratt (PRA) 04401. Laboratory mixtures of Murchison CM2 carbonaceous chondrite and basaltic eucrite Millbillillie also show band depth and albedo affinity to DM. Modeling of carbonaceous chondrite abundance in DM (1-6 vol%) is consistent with howardite meteorites. We find no evidence for large-scale volcanism (exposed dikes/pyroclastic falls) as the source of DM. Our modeling efforts using impact crater scaling laws and numerical models of ejecta reaccretion suggest the delivery and emplacement of this DM on Vesta during the formation of the ~400 km Veneneia basin by a low-velocity (<2 km/sec) carbonaceous impactor. This discovery is important because it strengthens the long-held idea that primitive bodies are the source of carbon and probably volatiles in the early Solar System.Comment: Icarus (Accepted) Pages: 58 Figures: 15 Tables:

    Primary care practitioners’ diagnostic action when the patient may have cancer : an exploratory vignette study in 20 European countries

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    Availability of data To avoid the risk of identification of individual participants, the datasets generated and analysed during the current study are not publicly available. However, they are available (with any possible identifying information redacted) from the corresponding author on reasonable request. Funding This study received no specific grant from any funding agency in the public, commercial or not-for-profit sectors. ALN’s time is supported by the National Institute for Health Research (NIHR) Imperial Patient Safety Translation Research Centre, with her infrastructure support provided by the NIHR Imperial Biomedical Research Centre (BRC). Acknowledgements We would like to thank all the PCPs who piloted the questionnaire and those who completed the survey. We would also like to thank the European GP Research Network for its support. We are grateful to Prof. Barbara Silverman and Prof. Lital Keinan for the data on cancer survival rates in Israel, and to Dr Yochai Schonmann for his work on those data. Two of the vignettes were used by kind permission of the ICBP; we also thank Dr Peter Murchie and Dr Rhona Auckland, who generously provided the other two vignettes. Prof. Antonius Schneider kindly organised the Technical University of Munich’s data collection.Peer reviewedPublisher PD

    The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts

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    Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015

    A Global Inventory of Ice-Related Morphological Features on Dwarf Planet Ceres: Implications for the evolution and current state of the cryosphere

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    We present a comprehensive global catalog of the geomorphological features with clear orpotential relevance to subsurface ice identified during the Dawn spacecraft’s primary and first extended missions at Ceres. We define eight broad feature classes and describe analyses supporting their genetic links to subsurface ice. These classes include relaxed craters; central pit craters; large domes; small mounds; lobate landslides and ejecta; pitted materials; depressions and scarps; and fractures, grooves, and channels. Features in all classes are widely distributed on the dwarf planet, consistent with multiple lines of observational evidence that ice is a key component of Ceres’ crust. Independent analyses of multiple feature types suggest rheological and compositional layering may be common in the upper ~10 km of the crust. Clustering of features indicates that ice concentration is heterogeneous on nearly all length scales, from ~1 km to hundreds of kilometers. Impacts are likely the key driver of heterogeneity, causing progressive devolatilization of the low latitude and midlatitude crust on billion-year timescales but also producing localized enhancements in near surface ice content via excavation of deep ice-rich material and possible facilitation of cryomagmatic and cryovolcanic activity. Impacts and landslides may be the dominant mechanism for ice loss on modern Ceres. Our analysis suggests specific locations where future high-resolution imaging can be used to probe (1) current volatile loss rates and (2) the history of putative cryomagmatic and cryovolcanic features. The Cerean cryosphere and its unique morphology promise to be a rich subject of ongoing research for years to come
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