排序方式: 共有65条查询结果,搜索用时 15 毫秒
51.
Ramos Claudete Gindri dos Santos de Medeiros Diego Gomez Leandro Oliveira Luis Felipe Silva Schneider Ivo André Homrich Kautzmann Rubens Muller 《Natural Resources Research》2020,29(3):1583-1600
Natural Resources Research - This study was focused on physical, petrographical, mineralogical, and chemical characterization of a volcanic-rock mining by-product (dacite rock), as well as on... 相似文献
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vila Leandro Mine Miriam R. M Kaviski Eloy 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(7):931-947
Stochastic Environmental Research and Risk Assessment - This paper explores and combines implicit stochastic optimization (ISO) with copula functions to simulate long-term operating policies for a... 相似文献
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The medium-sized cities of Brazil are those with populations of between 100,000 and 500,000 inhabitants. These cities are growing rapidly, and are characterized by poor urban planning, a loss of biodiversity and decreasing health prospects for residents. Historically, urbanization in Brazil has been associated with incentives to increase the use of private vehicles for local transport. The air pollution resulting from this “car dependency” has been quantified in some major cities in Brazil, such as the megacity of São Paulo. In this paper, we demonstrate through a bioindication study carried out in the Brazilian city of Rondonópolis, that atmospheric pollution resulting from vehicular emissions is also a measurable reality for medium-sized cities. Most Brazilian cities lack air quality measurement equipment, and we used an inexpensive and easy to apply bioindication assay to measure air pollution, and this approach could be easily implemented in those cities and beyond. 相似文献
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Bijeesh Kozhikkodan Veettil Ulisses Franz Bremer Sergio Florêncio de Souza Éder Leandro Bayer Maier Jefferson Cardia Simões 《国际地球制图》2016,31(5):544-556
This research focuses on the recent variations in the annual snowline and the total glaciated area of the Nevado Coropuna in the Cordillera Ampato, Peru. Maximum snowline altitude towards the end of dry season is taken as a representative of the equilibrium line altitude of the year, which is an indirect measurement of the annual mass balance. We used Landsat and IRS LISS3 images during the last 30 years due to its better temporal coverage of the study site. It is found that there was a decrease of 26.92% of the glaciated area during 1986–2014. We calculated the anomalies in precipitation and temperature in this region and also tried to correlate the changes in glacier parameters with the combined influence of El Niño – Southern Oscillation (ENSO) and pacific decadal oscillation (PDO). It is concluded that the snowline of Nevado Coropuna has been fluctuated during ENSO, and maximum fluctuations were observed when ENSO and PDO were in phase. 相似文献
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Vargas Marcelle Martins Beskow Samuel de Mello Carlos Rogério de Moura Maíra Martim Nunes Maria Cândida Moitinho Faria Lessandro Coll Aquino Leandro Sanzi 《Natural Hazards》2021,109(1):593-614
Natural Hazards - Process-based hydrological models are of great importance to understand hydrological processes and support decision making. The LImburg Soil Erosion Model (LISEM) requires... 相似文献
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Leandro G. Althaus Alejandro H. Córsico Jordi Isern Enrique García-Berro 《Astronomy and Astrophysics Review》2010,18(4):471-566
White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. Since the coolest white
dwarfs are very old objects, the present population of white dwarfs contains a wealth of information on the evolution of stars
from birth to death, and on the star formation rate throughout the history of our Galaxy. Thus, the study of white dwarfs
has potential applications in different fields of astrophysics. In particular, white dwarfs can be used as independent reliable
cosmic clocks, and can also provide valuable information about the fundamental parameters of a wide variety of stellar populations,
such as our Galaxy and open and globular clusters. In addition, the high densities and temperatures characterizing white dwarfs
allow these stars to be used as cosmic laboratories for studying physical processes under extreme conditions that cannot be
achieved in terrestrial laboratories. Last but not least, since many white dwarf stars undergo pulsational instabilities,
the study of their properties constitutes a powerful tool for applications beyond stellar astrophysics. In particular, white
dwarfs can be used to constrain fundamental properties of elementary particles such as axions and neutrinos and to study problems
related to the variation of fundamental constants. These potential applications of white dwarfs have led to renewed interest
in the calculation of very detailed evolutionary and pulsational models for these stars. In this work, we review the essentials
of the physics of white dwarf stars. We enumerate the reasons that make these stars excellent chronometers, and we describe
why white dwarfs provide tools for a wide variety of applications. Special emphasis is placed on the physical processes that
lead to the formation of white dwarfs as well as on the different energy sources and processes responsible for chemical abundance
changes that occur along their evolution. Moreover, in the course of their lives, white dwarfs cross different pulsational
instability strips. The existence of these instability strips provides astronomers with a unique opportunity to peer into
their internal structure that would otherwise remain hidden from observers. We will show that this allows one to measure stellar
masses with unprecedented precision and to infer their envelope thicknesses, to probe the core chemical stratification, and
to detect rotation rates and magnetic fields. Consequently, in this work, we also review the pulsational properties of white
dwarfs and the most recent applications of white dwarf asteroseismology. 相似文献
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Andrea Koschinsky Richard SeifertPeter Halbach Michael BauSabine Brasse Leandro M de CarvalhoNuno M Fonseca 《Geochimica et cosmochimica acta》2002,66(8):1409-1427
Low-temperature (<13°C) diffuse hydrothermal fluids were sampled directly at the seafloor with a specially designed Hydro Bottom Station in the North Fiji Basin and analyzed for gases, major and minor elements, and a large number of trace metals. The fluids were significantly enriched in CO2, Si, Li, Rb, Cs, Ba, Mn, and several trace metals compared to ambient seawater, had high CH4 and H2S concentrations, and had a slightly decreased salinity. Calculated end-member concentrations of the low-temperature fluids show a strong similarity to the neighboring hot vents, implying that the diffuse fluids are hot vent waters diluted by seawater. According to the chemical composition, the sampled fluids derive from vapor-phase fluids produced by subseafloor boiling and phase separation. Compared to hot vents from other regions, Mn, Fe, and other trace metal concentrations are low. Subsurface metal sulfide precipitation during cooling and dilution with seawater has further decreased the dissolved metal contents of the diffuse fluids, thus creating a very favorable environment for the hydrothermal fauna, as indicated by a very low Fe/H2S ratio. Therefore, the fluids support high bioproductivity but no hydrothermal mineral precipitation. The emanation of the condensed vapor phase appears to have been stable during the past 10 years; however, the occurrence of metal sulfide particles in some fluid and sediment samples and small areas of dead fauna indicate that the hydrothermal system may be evolving toward the emanation of the stored brine phase. 相似文献