A study of synthetic and natural uranium oxides by X-ray photoelectron spectroscopy

Synthetic and natural uranium oxides UO _x (2≦×≦3) have been studied with X-ray photoelectron spectroscopy (XPS) to determine the phase composition and content of uranium ions in uraninites with a varying degree of oxidation. A strong hybridization of U_6p and O_2s orbitals has been found which permits a quantitative assessment of the U-O bond lengths. The values of such bonds in some substances have been found to be smaller than those in synthetic U(VI) oxide. The oxides U₂O₅ and U₃O₈ contain two types of uranium ions with a varying degree of oxidation.     

Contribution of thermal bremsstrahlung to microwave emission of solar flare loops

The contribution of thermal bremsstrahlung to the total microwave flux of a solar flare loop is considered. The total-flux data were obtained on the Nobeyama Radio Heliograph. The calculation of the thermal bremsstrahlung radio flux was based on determining the integrated temperature and number density of the hot flare-loop plasma from its soft X-ray flux, obtained using data from the GOES-10 and GOES-12 satellites. The effect of thermal bremsstrahlung on the total flux and the spectral index of the microwave radiation is insignificant at the burst maximum (F _th/F _tot < 3%, Δα < 0.2), while the contribution of bremsstrahlung can be substantial during the decay phase of the burst (up to 80%). This results in an appreciable decrease in the observed spectral index (to Δα ～ 1.5). Therefore, when diagnosing the parameters of the accelerated electrons based on the characteristics of their gyrosynchrotron radiation, the most accurate results can be obtained using the emission characteristics obtained near the burst maximum.     

Long-period pulsations of the thermal microwave emission of the solar flare of June 2, 2007 from data with high spatial resolution

Data from the Nobeyama Radioheliograph at 17 GHz with high spatial and temporal resolution are used to detect quasi-periodic pulsations with periods from 55 to 250 s in the thermal component of the microwave emission of a solar flare loop observed on June 2, 2007. Observed pulsations with periods of about 110–120 s are co-phased along the entire loop axis. The observed periodicity is most likely due to modulation of the radio emission by slow magnetoacoustic waves trapped in the filamentary flare loop.     

New evidence of the nonglaciated development of the northern part of the Western Siberian lowland in the Quaternary period

To solve the controversially debated problem related to the areal extent of the ice sheet in Western Siberia in the Quaternary period, we have studied the development of cold born objects of this area estimating the relationships between them in terms of cryogenic diversity. We have obtained a field of new cross data related to the development of cryogenic and glacial phenomena, their relationship, and traces they left. The research showed that, in this area, the trend of rock freezing is clearly reflected in the Quaternary formations, but there were no conditions for ice sheet development even during the cryochrons.     

New paleontological data on Govorov,Vulkanolog, and Kocebu guyots (Magellan Seamounts,Pacific)

The work aims to present new biostratigraphic data on Govorov, Vulkanolog, and Kocebu guyots of the western branch of the Magellan Seamounts (NW Pacific). The data were obtained during the voyage of R/V Gelendzhik in 2014. Analysis of the paleontological data on planktonic foraminifers, radiolarians, and corals allows us to distinguish several stratigraphic levels, ranging from Early Cretaceous to Pleistocene in age, which define the stages of geological development of the studied area. Based on the representative material on the planktonic foraminifers from layer I-2 of the ore crusts on Govorov guyot, it is established that this layer was deposited in the narrow age interval of 40.0–40.5 Ma. The data obtained clearly indicate the connection of the crust ore genesis on the seamounts with regional paleoceanic events.     

Mineralogy and Geochemistry of Co-bearing manganese crusts from the Govorov and Volcanologist guyots of the Magellan Seamounts (Pacific Ocean)

Co-bearing manganese crusts (CMCs) from the Govorov and Volcanologist guyots (Magellan Seamounts, Pacific Ocean) are of the same type and consist of three layers (I-1, II, III) and a “dried crust” variety of layer III. It is shown that the structural and textural pattern are quite similar within individual layers. The major ore minerals of the crusts are poorly crystallized, have a low degree of structural ordering, and include Fe-vernadite, Mn-feroxyhyte, and less abundant, well-crystallized, and structurally ordered vernadite. It is shown that the cations of ore (Со, Ni, Cu), rare, and rare-earth metals are irregularly concentrated in ore minerals of CMCs, which provides evidence for the pulsating nature of their supply at different geological stages.     

Learning about parameter and structural uncertainty in carbon cycle models

Uncertainty in the response of the global carbon cycle to anthropogenic emissions plays a key role in assessments of potential future climate change and response strategies. We investigate how fast this uncertainty might change as additional data on the global carbon budget becomes available over the twenty-first century. Using a simple global carbon cycle model and focusing on both parameter and structural uncertainty in the terrestrial sink, we find that additional global data leads to substantial learning (i.e., changes in uncertainty) under some conditions but not others. If the model structure is assumed known and only parameter uncertainty is considered, learning is rather limited if observational errors in the data or the magnitude of unexplained natural variability are not reduced. Learning about parameter values can be substantial, however, when errors in data or unexplained variability are reduced. We also find that, on the one hand, uncertainty in the model structure has a much bigger impact on uncertainty in projections of future atmospheric composition than does parameter uncertainty. But on the other, it is also possible to learn more about the model structure than the parameter values, even from global budget data that does not improve over time in terms of its associated errors. As an example, we illustrate how one standard model structure, if incorrect, could become inconsistent with global budget data within 40 years. The rate of learning in this analysis is affected by the choice of a relatively simple carbon cycle model, the use of observations only of global emissions and atmospheric concentration, and the assumption of perfect autocorrelation in observational errors and variability. Future work could usefully improve the approach in each of these areas.