451 research outputs found
Raman spectroscopic thermometer for carbonaceous material in chondrites
第6回極域科学シンポジウム[OA] 南極隕石11月16日(月) 国立国語研究所 2階 講
How large are departures from lithostatic pressure? Constraints from host-inclusion elasticity
Minerals trapped as inclusions within other host minerals will develop non-lithostatic pressures during both prograde and retrograde metamorphism because of the differences between the thermo-elastic properties of the host and inclusion phases. There is only a single possible path in P-T space, the entrapment isomeke, along which no residual pressure would be developed in a host/inclusion system; non-lithostatic pressures are developed in inclusions as a result of the external pressure and temperature deviating from the isomeke that passes through the entrapment conditions. With modern equation of state and elasticity data for minerals now available it is possible to perform precise calculations of the isomekes for mineral pairs. These show that isomeke lines are not straight lines in P-T space at metamorphic conditions. We show that silicate inclusions in silicate hosts tend to have flat isomekes, with small values of dP/dT(isomeke), because of the small range of thermal expansion coefficients of silicate minerals. As a consequence, the general behaviour under decompression is for soft silicate inclusions in stiffer hosts to develop excess pressures, whereas a stiff silicate inclusion in a softer matrix will experience lower pressures than lithostatic pressure. The opposite effects occur for compression after entrapment on the prograde path. The excess pressures in inclusions, including allowance for mutual elastic relaxation of the host and inclusion, are most easily calculated by using the isomeke as a basis. Analysis of the simplest possible model of a host-inclusion system indicates that deviations from lithostatic pressure in excess of 1 GPa can be readily produced in quartz inclusions within garnets in metamorphic rocks. For softer host minerals such as feldspars the pressure deviations are smaller, because of greater elastic relaxation of the host. The maximum pressure deviation from lithostatic pressure in the host phase around the inclusion is one-third of the pressure deviation in the inclusion. Routines for performing these calculations have been added to the EosFit7c software package
Sanbagawa Subduction : What Went in, How Deep, and How Hot did it Get?
The Sanbagawa belt is a “coherent” oceanic subduction-type metamorphic region representing a rock package predominantly derived from oceanic crust and accreted at depths of 20–80 km (300–700 °C). The thermal structure and lithological layers are complexly deformed but semi-continuous, in contrast to more commonly reported subduction-related domains dominated by mélange. The coeval Shimanto accretionary complex records accretion at depths <15 km and the rocks are primarily terrigenous sediments. The Sanbagawa belt has a greater proportion of mafic rocks than the Shimanto complex, implying progressive peeling-off of oceanic plate stratigraphy with more basaltic oceanic crust slices accreted at deeper levels. Tectonic exhumation can be explained by three separate phases dominated by buoyancy-driven upflow, ductile thinning, and normal faulting
Seasonal variation in the correlation between anomalies of sea level and chlorophyll in the Antarctic Circumpolar Current
The Antarctic Circumpolar Current (ACC) has highly energetic mesoscale phenomena, but their impacts on phytoplankton biomass, productivity, and biogeochemical cycling are not understood well. We analyze satellite observations and an eddy‐rich ocean model to show that they drive chlorophyll anomalies of opposite sign in winter versus summer. In winter, deeper mixed layers in positive sea surface height (SSH) anomalies reduce light availability, leading to anomalously low chlorophyll concentrations. In summer with abundant light, however, positive SSH anomalies show elevated chlorophyll concentration due to higher iron level, and an iron budget analysis reveals that anomalously strong vertical mixing enhances iron supply to the mixed layer. Features with negative SSH anomalies exhibit the opposite tendencies: higher chlorophyll concentration in winter and lower in summer. Our results suggest that mesoscale modulation of iron supply, light availability and vertical mixing plays an important role in causing systematic variations in primary productivity over the seasonal cycle
Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment (INBOX): Part 3. Mesoscale variability of dissolved oxygen concentrations observed by multiple floats during S1-INBOX
As part of the interdisciplinary project S1-INBOX (Western North Pacific Integrated Physical-Biogeochemical Ocean Observation Experiment conducted around the S1 biogeochemical mooring site), we used data from more than 18 floats and a biogeochemical mooring S1 (near 30° N, 145° E) to investigate temporal and spatial changes in the shallow oxygen maximum (SOM) associated with a mesoscale cyclonic eddy. On the northern edge of the cyclonic eddy, patches (linear dimensions of 20–40 km) with relatively high oxygen concentrations were observed around the SOM. The patterns of the oxygen concentrations reflected the fact that changes of the depths of the isopycnal surfaces were caused by small disturbances associated with the eddy structure along the eddy edge. The implication is that nutrient-rich water was supplied by upward isopycnal heaving at the edge of the eddy and contributed to the formation of the high-oxygen patches. As relatively high oxygen concentrations on the same isopycnal surfaces at greater depths were sometimes observed in the region downstream of the high-oxygen patches, we suggest that the patches were advected to the downstream region. The high-oxygen water seemed to extend into the eddy core from its edge. Ageostrophic secondary circulation around the edge of the eddy might have contributed to maintenance of the high oxygen concentrations in the eddy core, and these high oxygen concentrations may have been formed during spin-up of the eddy by heaving of isopycnal surfaces
Como são abordados o empreendedorismo e a inovação em uma das principais universidades da Suécia? : análise comparativa com o contexto brasileiro
Orientador: Prof. Dr. Rodrigo Luiz Morais-da-SilvaArtigo apresentado como Trabalho de Conclusão de CursoArtigo (especialização) – Universidade Federal do Paraná, Setor de Ciências Sociais Aplicadas, Curso de Especialização MBA em Gestão EstratégicaInclui referênciasResumo: Este estudo analisa, por meio de dados documentais, o papel estratégico das universidades no estímulo à inovação e ao empreendedorismo, com foco na capitalização do conhecimento. A Suécia, reconhecida internacionalmente por seu desempenho em inovação e empreendedorismo, serve como contexto para investigar a relação entre universidade, indústria e governo e seu impacto socioeconômico. Este estudo relata as abordagens e iniciativas de uma universidade sueca específica, comparando esse contexto com os desafios enfrentados no Brasil e sugerindo possíveis ações. Este estudo de caso oferece insights sobre as práticas adotadas pela universidade sueca para promover a inovação e o empreendedorismo, fornecendo perspectivas valiosas para possíveis aprimoramentos e implementação de iniciativas ou programas que possam contribuir com o desenvolvimento brasileir
Pacific anthropogenic carbon between 1991 and 2017
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Carter, B. R., Feely, R. A., Wanninkhof, R., Kouketsu, S., Sonnerup, R. E., Pardo, P. C., Sabine, C. L., Johnson, G. C., Sloyan, B. M., Murata, A., Mecking, S., Tilbrook, B., Speer, K., Talley, L. D., Millero, F. J., Wijffels, S. E., Macdonald, A. M., Gruber, N., & Bullister, J. L. Pacific anthropogenic carbon between 1991 and 2017. Global Biogeochemical Cycles, 33(5), (2019):597-617, doi:10.1029/2018GB006154.We estimate anthropogenic carbon (Canth) accumulation rates in the Pacific Ocean between 1991 and 2017 from 14 hydrographic sections that have been occupied two to four times over the past few decades, with most sections having been recently measured as part of the Global Ocean Ship‐based Hydrographic Investigations Program. The rate of change of Canth is estimated using a new method that combines the extended multiple linear regression method with improvements to address the challenges of analyzing multiple occupations of sections spaced irregularly in time. The Canth accumulation rate over the top 1,500 m of the Pacific increased from 8.8 (±1.1, 1σ) Pg of carbon per decade between 1995 and 2005 to 11.7 (±1.1) PgC per decade between 2005 and 2015. For the entire Pacific, about half of this decadal increase in the accumulation rate is attributable to the increase in atmospheric CO2, while in the South Pacific subtropical gyre this fraction is closer to one fifth. This suggests a substantial enhancement of the accumulation of Canth in the South Pacific by circulation variability and implies that a meaningful portion of the reinvigoration of the global CO2 sink that occurred between ~2000 and ~2010 could be driven by enhanced ocean Canth uptake and advection into this gyre. Our assessment suggests that the accuracy of Canth accumulation rate reconstructions along survey lines is limited by the accuracy of the full suite of hydrographic data and that a continuation of repeated surveys is a critical component of future carbon cycle monitoring.The data we use can be accessed at CCHDO website (https://cchdo.ucsd.edu/) and GLODAP website (https://www.glodap.info/). This research would not be possible without the hard work of the scientists and crew aboard the many repeated hydrographic cruises coordinated by GO‐SHIP, which is funded by NSF OCE and NOAA OAR. We thank funding agencies and program managers as follows: U.S., Australian, Japanese national science funding agencies that support data collection, data QA/QC, and data centers. Contributions from B. R. C., R. A. F., and R. W. are supported by the National Oceanic and Atmospheric Administration Global Ocean Monitoring and Observing Program (Data Management and Synthesis Grant: N8R3CEA‐PDM managed by Kathy Tedesco and David Legler). G. C. J. is supported by the Climate Observation Division, Climate Program Office, National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce and NOAA Research (fund reference 100007298), grant (N8R1SE3‐PGC). B. M. S was supported by the Australian Government Department of the Environment and CSIRO through the Australian Climate Change Science Programme and by the National Environmental Science Program. N. G. acknowledges support by ETH Zurich. This is JISAO contribution 2018‐0149 and PMEL contribution 4786. We fondly remember John Bullister as a treasured friend, valued colleague, and dedicated mentor, and we thank him for sharing his days with us. He is and will be dearly missed
Efeitos da utilização do hidrogênio adicionado á mistura ar/combustível em um motor de combustão interna ciclo diesel
Efeitos da utilização do hidrogênio adicionado á mistura ar/combustível em um motor de combustão interna ciclo dieselEfeitos da utilização do hidrogênio adicionado á mistura ar/combustível em um motor de combustão interna ciclo diese
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