Formation of the Galactic Stellar Halo: Origin of the Metallicity-Eccentricity Relation

Motivated by the recently improved knowledge on the kinematic and chemical properties of the Galactic metal-poor stars, we present the numerical simulation for the formation of the Galactic stellar halo to interpret the observational results. As a model for the Galaxy contraction, we adopt the currently standard theory of galaxy formation based on the hierarchical assembly of the cold dark matter fluctuations. We find, for the simulated stars with &sqbl0;Fe&solm0;H&sqbr0;相似文献   

A note on the height dependence of the skewness and the kurtosis of the vertical turbulent velocity in the neutral surface layer

Several experimental results indicate that S _w (the skewness of the vertical turbulent velocity) increases with height, and K _w (the kurtosis) decreases with height in the neutral surface layer. The measured behavior of S _w and K _w with height under neutral conditions is shown to be consistent with available models for the gradient-diffusion and the pressure-velocity correlation. In addition, an estimate of the mode of the probability density distribution turns out to be helpful in interpreting the height dependence of K _w.     

Carbonate precipitation through photoautotrophic microorganisms at the Giza cliff in Okinawa,Japan

Environmentally friendly options for restoring limestone using microorganisms have attracted recent attention. The governing principle of this technique is to use the metabolism of microorganisms to precipitate carbonate in the gaps of mineral particles; this process is known as microbial carbonate precipitation (MCP). Here, an outcrop associated with MCP under natural conditions at the Giza cliff in Okinawa, Japan was investigated. Colonies of photoautotrophic microorganisms containing chlorophyll were found inhabiting a layer of limestone 2–4 mm below the surface of the outcrop. These microorganisms survived and photosynthesised within the limestone under favorable conditions that include an effective photon flux density of 15–75 µmol/m²/s, and some fresh calcium carbonates (i.e., calcite) were precipitated around the cell walls and extracellular polymeric substances (EPS) of the microorganisms. Furthermore, the results of powder X-ray diffraction (XRD) suggest that the synthetic calcite within the limestone may improve the mechanical strength of the outcrop. These in situ and laboratory findings indicate that these microbial functions may be applicable to some weathered rock surfaces as a self-organizing surface protection and conservation technology.