Scattering and transmission functions of radiation by finite atmospheres with reflecting surfaces

In the present paper, with the aid of invariance principles in connection with the scattering matrix, we get the exact solution of diffuse reflection and transmission problems by finite inhomogeneous, anisotropically scattering atmospheres bounded by reflecting sufaces. On making use of the reflection and transmission integral operators, we show how to obtain the non-linear integro-differential equations for these operators, which do not depend on the initial condition. Then, we have a system of the required integro-differential equations for the scattering and transmission functions. The obtained result is new, so far as we know. Finally, using the scattering matrix, we reduce the diffuse reflection and transmission problems for planetary atmospheres with reflecting surfaces to the standard diffuse reflection and transmission problems.Supported by the National Science Foundation under Grant No. GP29049 and the Atomic Energy Comminission, Division of Research under Contract No. AT(40-3)-133, Project 19.     

Characteristic features in Venus’ nightside cloud-top temperature obtained by Akatsuki/LIR

Mid-infrared images of almost the entire Venus nightside hemisphere obtained by the Longwave Infrared Camera (LIR) onboard Akatsuki on December 9 and 10, 2010 reveal that the brightness temperature of the cloud-top ranges from 237 K in the cold polar collars to 243 K in the equatorial region, significantly higher than the values obtained by Venera 15. Other characteristic features of the temperature distributions observed are zonal belt structures seen in the middle and low latitudes and patchy temperature structures or quasi-periodic streaks extending in a north–south direction in the northern middle latitudes and southern low latitudes.     

Decadal variation of temperature inversions along Line P

Hydrographic data measured for 50 years along Line P between the North American west coast and mid Gulf of Alaska as well as data from profiling float observations were analyzed to study the formation and variation of temperature inversions in the eastern subarctic North Pacific. Remarkable decadal to inter-decadal variation was observed in the magnitude of temperature inversions. This variation was mostly attributed to the variation of southward Ekman transport, eastward geostrophic transport, and surface cooling.     

Nature of accretion related to Paleo-Tethys subduction recorded in northern Thailand: Constraints from mélange kinematics and illite crystallinity

We reconstructed the accretion process related to Paleo-Tethys subduction recorded in northern Thailand, based on mélange and thrust structures, and metamorphic temperatures derived from illite crystallinity data. Mélange formation was characterized by hydrofracturing and cataclastic deformation, with mud injection under semi-lithified conditions followed by shear deformation and pressure solution. Illite crystallinity data suggest metamorphic temperatures below 250 °C during mélange formation. The combined structural and metamorphic data indicate that during mélange formation, the accretionary complex related to Paleo-Tethys subduction developed at shallow levels within an accretionary prism. Asymmetric shear fabrics in mélange indicate top-to-south shear. After correction for rotation associated with collision between the Indian and Eurasian continents, the trend of the Paleo-Tethys subduction zone is estimated to have been N80 °E. We conclude that the Paleo-Tethys was subducted northward beneath the Indochina Block from the Permian to Triassic.     

Micro-FTIR spectroscopic signatures of Bacterial lipids in Proterozoic microfossils

Precambrian microbial fossils show carbonaceous cellular structure, which often resemble in shape and size cyanobacteria and other prokaryotes. Morphological taxonomy of these minute, simple, and more or less degraded fossils is, however, often not enough to determine their precise phylogenetic positions. Here we report the results of micro-FTIR spectroscopic analyses of well-preserved microfossils in 850 Ma and 1900 Ma stromatolites, together with those of 8 species of extant prokaryotes and 5 of eukaryotes for comparison. These Proterozoic fossils have low CH₃/CH₂ absorbance ratios (R_3/2 < 0.5) of aliphatic CH moieties, suggesting selective preservation of long, straight, aliphatic carbon chains probably derived from bacterial membrane lipids. All the observed R_3/2 values of coccoids, filaments and amorphous organic matter resemble lipid fractions of extant Bacteria including cyanobacteria, but not Archaea. The results indicate that Proterozoic microfossils belong to Bacteria, which is consistent with the cyanobacterial origin inferred from morphology. Moreover, the R_3/2 value of fossilized cell would reflect chemical composition of its precursor membrane lipid, thus could be a useful new tracer for distinguishing Archaea, Bacteria and possibly Eucarya for fossilized and extant microorganisms.     

Single-crystal X-ray diffraction study of cation distribution in MgAl<Subscript>2</Subscript>O<Subscript>4</Subscript>–MgFe<Subscript>2</Subscript>O<Subscript>4</Subscript> spinel solid solution

Synthesis experiments in the system MgAl₂O₄–MgFe₂O₄ [MgAl_2–xFe_xO₄ (0 x 2)] were carried out using a PbF₂ flux. The crystalline products synthesized in the compositional range of 0.6 <x 1.2 consisted of two spinel phases, whereas those synthesized in the compositional ranges of 0.0 x 0.6 and 1.2 < x 2.0 crystallized as single spinel phases. Structure refinements of the spinel single crystals, which grew in the ranges of 0.0 x 0.6 and 1.2 < x 2.0, show that the degree of randomness of cation distribution between A and B sites increases as x approaches the two-phase region. This means that the degree of the size mismatch among Mg²⁺, Fe³⁺ and Al³⁺occupying each equivalent mixing site increases as x approaches the two-phase region. Consequently, if the coexistence of two spinels observed in the intermediate compositions reveals the existence of a miscibility gap at low temperatures, this increase in the degree of the size mismatch among the three cations is suggested as a factor of energetic destabilization to form the miscibility gap.