910 resultados para Physical and chemical properties
Resumo:
The aim of this paper is to provide a review of general processes related to plasma sources, their transport, energization, and losses in the planetary magnetospheres. We provide background information as well as the most up-to-date knowledge of the comparative studies of planetary magnetospheres, with a focus on the plasma supply to each region of the magnetospheres. This review also includes the basic equations and modeling methods commonly used to simulate the plasma sources of the planetary magnetospheres. In this paper, we will describe basic and common processes related to plasma supply to each region of the planetary magnetospheres in our solar system. First, we will describe source processes in Sect. 1. Then the transport and energization processes to supply those source plasmas to various regions of the magnetosphere are described in Sect. 2. Loss processes are also important to understand the plasma population in the magnetosphere and Sect. 3 is dedicated to the explanation of the loss processes. In Sect. 4, we also briefly summarize the basic equations and modeling methods with a focus on plasma supply processes for planetary magnetospheres.
Resumo:
After the development of the viral-based prostate cancer vaccine, Ad5-PSA, much research has been orientated to help enhance the induced immune response by combining the vaccine with physical and chemical modulating agents, more specifically the polymers polyethylenimine (PEI), chitosan, and chitosan coated with CD3 complex antibodies; all previously shown to stimulate an immune response as isolated gene carriers. To compare the vaccine-induced immune responses between the naked vaccine and the polymer-vaccine combinations, a mouse model using the ovalbumin- specific Ad-OVA vaccine was tested using intracellular cytokine staining (ICS), tetramer staining, and cytotoxic T-cell lymphocyte assays to measure the activation of CD8+ T-cells, interferon gamma proteins (INFƒ×), and the induced cytotoxicity to ovalbumin. The Ad-OVA vaccine combined with both chitosan and chitosan with CD3 complex antibodies, both natural polymers, were found to induce similar immune responses to the naked vaccine while the vaccine combined with the synthetic polymer, PEI, diminished the immune response.
Resumo:
Sediment composition and rate of deposition are the primary factors responsible for determining the spatial distribution of geotechnical properties on the Wring Plateau. Grain size and depth of burial have no significant influence. Vertical and lateral changes in geotechnical properties are associated with vertical and lateral composition changes in which biogenic silica is the most important variable. Anomalous trends of decreasing density and increasing porosity and water content with depth are associated with increasing silica content downsection. Void ratios, inferred in-situ permeability, and change in void ratio during consolidation testing are relatively high in siliceous sediments and tend to increase as the biogenic silica content increases. Portions of the section are overconsolidated, probably as a result of changes in sediment accumulation rates. However, the higher permeabilities of siliceous sediments may also be a factor influencing consolidation state.
Resumo:
We analyzed the abundance of Scots pine regeneration in a 257 ha wildfire in an inner-alpine forest. We sampled regeneration, percent soil cover by classes, physical and chemical properties of topsoils (A horizon, 0-5 cm) under four fire severity levels (unburned, moderate, moderate/high, high severity). 5 plots per severity level, circular (R= 3m). Analysis methods for soil properties as described in the paper.
Resumo:
Data from sections across the Eurasian Basin of the Arctic Ocean occupied by the German Research Vessel Polarstern in 1987 and by the Swedish icebreaker Oden in 1991 are used to derive information on the freshwater balance of the Arctic Ocean halocline and on the sources of the deep waters of the Nansen, Amundsen and Makarov basins. Salinity, d18O and mass balances allow separation of the river-runoff and the sea-ice meltwater fractions contained in the Arctic halocline. This provides the basis for tracking the river-runoff signal from the shelf seas across the central Arctic Ocean to Fram Strait. The halocline has to be divided into at least three lateral regimes: the southern Nansen Basin with net sea-ice melting, the northern Nansen Basin and Amundsen Basin with net sea-ice formation and increasing river-runoff fractions, and the Canadian Basin with minimum sea-ice meltwater and maximum river-runoff fractions and water of Pacific origin. In the Canadian Basin, silicate is used as a tracer to identify Pacific water entering through Bering Strait and an attempt is made to quantify its influence on the halocline waters of the Canadian Basin. For this purpose literature data from the CESAR and LOREX ice camps are used. Based on mass balances and depending on the value of precipitation over the area of the Arctic Ocean the average mean residence time of the river-runoff fraction contained in the Arctic Ocean halocline is determined to be about 14 or 11 years. Water column inventories of river-runoff and sea-ice meltwater are calculated for a section just north of Fram Strait and implications for the ice export rate through Fram Strait are discussed. Salinity, tritium, 3He and the d18O ratio of halocline waters sampled during the 1987 Polarstern cruise to the Nansen Basin are used to estimate the mean residence time of the river-runoff component in the halocline and on the shelves of the Arctic Ocean. These estimates are done by comparing ages of the halocline waters based on a combination of tracers yielding different time information: the tritium 'vintage' age which records the time that has passed since the river-runoff entered the shelf and the tritium/3He age which reflects the time since the shelf waters left the shelf. The difference between the ages determined by these two methods is about 3 to 6 years. Correction for the initial tritium/3He age of the shelf waters (about 0.5 to 1.5 years) yields a mean residence time of the river-runoff on the shelves of about 3.5 ± 2 years. Comparison of the 18O/16O ratios of shelf water, Atlantic water and the deep waters of the Arctic Ocean indicate that the sources of the deep and bottom waters of the Eurasian Basin are located in the Barents and Kara seas.
Resumo:
Based on the data of synchronous observations of hydrophysical and biogeochemical parameters in the near-mouth and shallow-water areas of the northern Caspian in 2000-2001, the scale of spatiotemporal variability in the following characteristics of the water-bottom system was estimated (1) flow velocity and direction within vortex structures formed by the combined effect of wind, discharge current, and the presence of higher aquatic plants; (2) dependence of the spatial distribution of the content and composition of suspended particulate matter on the hydrodynamic regime of waters and development of phytoplankton; (3) variations in the grain-size, petrographic, mineralogical, and chemical compositions of the upper layer of bottom sediments at several sites in the northern Caspian related to the particular local combination of dominant natural processes; and (4) limits of variability in the group composition of humus compounds in bottom sediments. The acquired data are helpful in estimating the geochemical consequences of a sea level rise and during the planning of preventive environmental protection measures in view of future oil and gas recovery in this region.
Resumo:
The accumulation and distribution of the 2H content of near-surface layers in the eastern part of the Ronne Ice Shelf were determined from 16 firn cores drilled to about 10 m depth during the Filchner IIIa and IV campaigns in 1990 and 1992, respectively. The cores were dated stratigraphically by seasonal d2H variations in the firn. In addition, 3H and high-resolution chemical profiles were used to assist in dating. Both the accumulation rate and the stable-isotope content decrease with increasing distance from the ice edge: the d2H values range from about -195 per mil at the ice edge to -250 per mil at BAS sites 5 and 6, south of Henry Ice Rise, and the accumulation rates from about 210 to 90 kg/m**2/a. The d2H values of the near-surface firn and the 10 m firn temperatures (Theta) at individual sites are very well correlated: ddelta2H/dTheta=(10.3±0.6)per mil /K; r = 0.97. The d2H profiles of the two ice cores B13 and B15 drilled in 1990 and 1992 to 215 and 320 m depth, respectively, reflect the gradual depletion in 2H in the firn upstream of the drill sites. Comparison with tlie surface data indicates that the ice above 142 m in core B15 and above 137 m in core B13 was deposited on the ice shelf, whereas the deeper ice, down to 152.8 m depth, most probably originated from the margin of the Antarctic ice sheet.
Resumo:
This data on the distribution of the accumulation rate and 18O content of near-surface layers in the eastern part of the Ronne Ice Shelf, Antarctica, were derived from an analysis of 16 firn cores. The firn cores were drilled along the traverse route of the Filchner-V-Campaign in 1995. The traverse followed an ice flowline of the Foundation Ice Stream and reached the margin of the inland ice, an area which has not yet been investigated. On the ice shelf the accumulation rates decrease with distance from the coast. Ascending to the inland ice the accumulation rates again reach almost coastal values. This regional distribution is in agreement with the temperature gradient along the traverse. The 18O content of the near-surface layers is closely related to the 10 m firn temperature. They strongly decrease from the grounding line towards the inland ice. At the southernmost site at 1100 m a.s.l., the mean d18O value of the firn decreases to -40?. Ice with that isotopic signature was found in cores from the central part of the Ronne Ice Shelf just above the marine ice layer, indicating that it originates from this area. All ice deposited as snow further south was melted beneath the ice shelf after passing the grounding-line area. The time series of accumulation rate and 18O content reveal no climatic trend during the last 30-50 years.