1,039 research outputs found
The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary
A major trough ("Belgica Trough") eroded by a palaeo-ice stream crosses the continental shelf of the southern Bellingshausen Sea (West Antarctica) and is associated with a trough mouth fan ("Belgica TMF") on the adjacent continental slope. Previous marine geophysical and geological studies investigated the bathymetry and geomorphology of Belgica Trough and Belgica TMF, erosional and depositional processes associated with bedform formation, and the temporal and spatial changes in clay mineral provenance of subglacial and glaciomarine sediments.
Here, we present multi-proxy data from sediment cores recovered from the shelf and uppermost slope in the southern Bellingshausen Sea and reconstruct the ice-sheet history since the last glacial maximum (LGM) in this poorly studied area of West Antarctica. We combined new data (physical properties, sedimentary structures, geochemical and grain-size data) with published data (shear strength, clay mineral assemblages) to refine a previous facies classification for the sediments. The multi-proxy approach allowed us to distinguish four main facies types and to assign them to the following depositional settings: 1) subglacial, 2) proximal grounding-line, 3) distal sub-ice shelf/sub-sea ice, and 4) seasonal open-marine. In the seasonal open-marine fades we found evidence for episodic current-induced winnowing of near-seabed sediments on the middle to outer shelf and at the uppermost slope during the late Holocene.
In addition, we obtained data on excess Pb-210 activity at three core sites and 44 AMS C-14 dates from the acid-insoluble fraction of organic matter (AIO) and calcareous (micro-) fossils, respectively, at 12 sites. These chronological data enabled us to reconstruct, for the first time, the timing of the last advance and retreat of the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet (APIS) in the southern Bellingshausen Sea. We used the down-core variability in sediment provenance inferred from clay mineral changes to identify the most reliable AIO C-14 ages for ice-sheet retreat. The palaeo-ice stream advanced through Belgica Trough after similar to 36.0 corrected C-14 ka before present (B.P.). It retreated from the outer shelf at similar to 25.5 ka B.P, the middle shelf at similar to 19.8 ka B.P., the inner shelf in Eltanin Bay at similar to 12.3 ka B.P., and the inner shelf in Ronne Entrance at similar to 6.3 ka B.P. The retreat of the WAIS and APIS occurred slowly and stepwise, and may still be in progress. This dynamical ice-sheet behaviour has to be taken into account for the interpretation of recent and the prediction of future mass-balance changes in the study area. The glacial history of the southern Bellingshausen Sea is unique when compared to other regions in West Antarctica, but some open questions regarding its chronology need to be addressed by future work. (C) 2010 Elsevier Ltd. All rights reserved
5G and AI technology application in the AMTC learning factory
5G and AI (Artificial Intelligence) are changing industrial production and offer great potential for manufacturing enterprises. One of the effects resulting from the increasing quantity of production data is the increasing demands of transmission of large amounts of data, fast transmission speed, and rapid data analysis. However, merely relying on traditional communication technology and manual data processing does not lead to high transmission performance and low analysis time. It is essential to integrate 5G and AI technology to flexibly transmit large amounts of data and real-time data. To demonstrate the feasibility and potential of these two technologies, a concept was developed at the Advanced Manufacturing Technology Center (AMTC) at the Tongji University (Shanghai, China) and further implemented in the AMTC learning factory in cooperation with wbk of Karlsruhe Institute of Technology (Karlsruhe, Germany) and Ruhr-University Bochum (Bochum, Germany). This paper presents the learning factory design in detail, describing the concept design, training environment and training phases in the AMTC learning factory. It is followed by a case study consisting of specific examples of 5G and AI, implemented in the AMTC learning factory. The importance of integrated 5G and AI applications is pointed out and discussed
Factors Affecting the Adoption of Faculty-Developed Academic Software: A Study of Five iCampus Projects
Instruction in higher education must adapt more rapidly to: changes in workforce needs, global issues, advances in disciplines, and resource constraints. The pace of such improvement depends on the speed with which new ideas and materials are adopted across institutions. In 1999 Microsoft pledged $25 million and staff support for iCampus, a seven-year MIT project to develop pioneering uses of educational technology. The TLT Group studied five iCampus projects in order to identify factors affecting institutionalization and widespread dissemination. Among the factors impeding adoption: lack of rewards and support for faculty to adopt innovations; faculty isolation; and a lack of attention to adoption issues among projects selected for funding. The study made recommendations for universities, foundations, government agencies and corporations: 1) continue making education more authentic, active, collaborative, and feedback-rich; 2) create demand to adopt ideas and materials from other sources by encouraging all faculty members to improve and document learning in their programs, year after year; 3) nurture coalitions for instructional improvement, across and within institutions; 4) create more effective higher education corporate alliances; and 5) improve institutional services to support faculty in educational design, software development, assessment methods, formative evaluation, and/or in sharing ideas with others who teach comparable courses
Cohort Profile of the International Spinal Cord Injury Community Survey Implemented in 22 Countries
Objectives: To detail the methodological features of the first International Spinal Cord Injury (InSCI) Community Survey by describing recruitment and data collection procedures, and to report on the recruitment results and basic characteristics of participants by country and income setting. Design: Cross-sectional survey. Setting: Community setting in 22 countries representing all 6 World Health Organization regions. Participants: Individuals (N = 12,591) with traumatic or non-traumatic spinal cord injury (SCI) aged over 18 years. Interventions: Not applicable. Main Outcome Measures: Recruitment and data collection procedures, recruitment results, and basic sociodemographic and lesion characteristics of participants. Results: Eight countries used predefined sampling frames and 14 countries applied convenience sampling for recruitment. Most countries recruited participants through specialized rehabilitation facilities, patient organizations, or acute and general hospitals. Modes of approaching potential participants depended on the sampling strategy and multiple response modes were offered to maximize participation. Contact rates ranged from 33% to 98%, cooperation rates ranged from 29% to 90%, and response rates ranged from 23% to 54%. The majority of participants were men (73%), the median age was 52 years (interquartile range, 40-63y), 60% had a partner, 8% reported that they were born in another country than where they were currently residing, and the median length of education was 12 years (interquartile range, 9-15y). Paraplegia was the main diagnosis (63%), traumatic etiologies were the major cause of injury (81%), and the median time since injury (TSI) was 9 years (interquartile range, 4-19y). Compared with participants from lower income settings, participants from higher income settings were over-represented and, in general, were older, more often diagnosed with tetraplegia, had a longer TSI, higher education, and were more often born in a country different than their current residence country. Conclusions: The successful implementation of the InSCI survey enables the comparison of the situation of individuals with SCI around the world and constitutes a crucial starting point for an international learning experience. (C) 2020 by the American Congress of Rehabilitation Medicin
Only small changes in soil organic carbon and charcoal concentrations found one year after experimental slash-and-burn in a temperate deciduous forest
International audienceAnthropogenic fires affected the temperate deciduous forests of Central Europe over millennia. Biomass burning releases carbon to the atmosphere and produces charcoal, which potentially contributes to the stable soil carbon pools and is an important archive of environmental history. The fate of charcoal in soils of temperate deciduous forests, i.e. the processes of charcoal incorporation and transportation, and the effects on soil organic matter are still not clear. In a long-term experimental burning site, we investigated the effects of slash-and-burn and determined soil organic carbon, charcoal carbon and nitrogen concentrations and the soil lightness of colour (L*) in the topmost soil material (0?1, 1?2.5 and 2.5?5 cm depths) before, immediately after the fire and one year after burning. The main results are that (i) only few charcoal particles from the forest floor were incorporated into the soil matrix by soil mixing animals. In 0?1 cm and during one year, the charcoal C concentrations increased only by 0.4 g kg?1 and the proportion of charcoal C to SOC concentrations increased from 2.8 to 3.4%; (ii) the SOC concentrations did not show any significant differences; (iii) soil lightness significantly decreased in the topmost soil layer and correlated with the concentrations of charcoal C (r=-0.87**) and SOC (r=?0.94**) in samples 0?5 cm. We concluded that the soil colour depends on the proportion of aromatic charcoal carbon in total organic matter and that Holocene burning could have influenced soil charcoal concentrations and soil colour
SAS-B digitized spark chamber gamma ray telescope
Systems description of SAS-B gamma ray telescope with multilayer digitized spark chamber for gamma rays with energy exceeding 20 Me
Changes in the Red Sea overturning circulation during Marine Isotope Stage 3
The oceanography of the Red Sea is controlled by the restricted exchange of water masses with the Indian Ocean and by high evaporation rates due to the arid climate of the surrounding land areas. In the northern Red Sea, the formation of oxygen-rich subsurface water ventilates the deeper parts of the basin, but little is known about the variability in this process in the past. The stable oxygen and carbon isotope records of epibenthic foraminifera from a sediment core of the central Red Sea and comparison with existing isotope records allow for the reconstruction of changes in the Red Sea overturning circulation (ROC) during Marine Isotope Stage 3. The isotope records imply millennial-scale variations in the ROC, in phase with the climate variability in the high northern latitudes. This suggests an immediate response of dense-water formation to the regional climate and hydrology of the northern Red Sea. Deep-water formation was intensified under the influence of cold and hyper-arid conditions during Heinrich stadials and was diminished during Dansgaard–Oeschger interstadials. While these changes are reflected in both stable oxygen and carbon isotope records, the latter data also exhibit changes in phase with the African–Indian monsoon system. The decoupling of the stable carbon and oxygen isotope records at the summer monsoon maximum centered around 55–60 ka may be associated with an increased inflow of nutrient-rich intermediate waters from the Arabian Sea to the central Red Sea. This process fueled local surface water productivity, resulting in enhanced remineralization of sinking organic matter and release of 12C at intermediate water depths.</p
Identificación y análisis de los recursos económicos asignados a la segunda locomotora. Evolución, aciertos y desaciertos
Con la elaboración del presente documento, se pretende identificar y analizar los recursos económicos asignados a una de las locomotoras del gobierno del presidente Juan Manuel Santos en el marco de su plan de desarrollo Prosperidad para todos y el impacto social de esta asignación de recursos en el agro Colombiano, Así mismo evaluar el cumplimiento de dicha política publica y la generación de bienestar social en la población."With the production of the present document, one tries to identify and to analyze the economic resources assigned to one of the locomotives of the government of the president Juan Manuel Santos in the frame of his plan of development "" Prosperity for all "" and the social impact of this assignment of resources in the Colombian agro, Likewise to evaluate the fulfillment of the above mentioned politics publishes and the generation of social well-being in the population.
Holocene history of the 79° N ice shelf reconstructed from epishelf lake and uplifted glaciomarine sediments
Acknowledgements This work was funded by a NERC standard grant (grant no. NE/N011228/1), and some radiocarbon analysis was funded by NEIF (grant NE/S011587/1; allocation number 2169.1118). We thank the Alfred Wegener Institute, particularly Angelika Humbert and Hicham Rafiq, for significant logistic support through the iGRIFF project. Additional support was provided by Station Nord (Jorgen Skafte), Nordlandair, Air Greenland, and the Joint Arctic Command. Naalakkersuisut (government of Greenland) provided scientific survey (VU-00121) and export (046/2017) licences for this work. Finally, we would like to thank our (Nanu Travel) field ranger Isak (and dog Ooni) for keeping us safe in the field and taking great pleasure in beating James A. Smith at cards. Financial support This research has been supported by the Natural Environment Research Council (grant no. NE/N011228/1).Peer reviewedPublisher PD
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