The cities of Russia: some recent trends and experience of regional and urban planning

The author examines the recent situation in the development of cities in Russia. Recent trends include a lack of growth and even a decrease in population; extensive economic restructuring; a grave ecological situation in cities; and recent peculiarities in the geopolitical situation and population migration. Due to the new economic, demographic, geopolitical and social situation in Russia it is necessary to re-evaluate the prospects for the development and growth of the big cities in this country. The system of basic documents for regional and city planning in the former USSR and in Russia includes different stages: from The General Scheme for the Settlement Systems of the Country and The Regional Territorial Complex Schemes of Environmental Protection in different regions to the detailed plans for the different parts of cities and towns. The shortcomings of this system and in the process of the realization of the schemes of regional planning and general plans for cities are documented.     

Sulfate-coated dust particles in the free troposphere over Japan

Airborne aerosol collections were performed over Wakasa bay (36°00′N, 135°30′E) in March and Kumano open sea (34°00′N, 136°50′E) and Seto (35°10′N, 137°10′E) in July 2001 at altitudes between 1.0 and 5.8 km. The particles were individually analyzed using transmission electron microscopy (TEM). Relatively large mineral-dust (mostly clay) particles were abundant in the March samples. They also dominated in July in the mid-troposphere higher than 4 km altitude, whereas sea salt and ammonium sulfate were more abundant at lower altitudes. Ca-coated grid samples show many traces of aqueous sulfate droplets. The proportions of former sulfate droplets to the total collected particles apparently increased with increasing relative humidity at the time of sampling. TEM analysis revealed that a significant fraction of these former droplets enclose mineral-dust particles as well as sea salt, soot, and fly ash. Some enclose mixtures of mineral-dust, sea-salt, soot, and fly ash particles. The results provide evidence that mineral dust from the Asian continent could acquire coatings of sulfate while being transported in the free troposphere. The mineral-dust particles probably acquired the sulfate coatings either through heterogeneous uptake of gaseous SO₂ and subsequent oxidation or through coagulation with cloud or fog droplets. The presence of the mixed particles in sulfate droplets also indicates that aggregation of particles of different origins occurred through cloud processing. Such sulfate-coated dust particles would affect cloud formation, precipitation, and chemistry of the free troposphere.     

Compositional variations and heterogeneity in fertile lithospheric mantle: peridotite xenoliths in basalts from Tariat,Mongolia

Clinopyroxene-rich, poorly metasomatised spinel lherzolites are rare worldwide but predominate among xenoliths in five Quaternary basaltic eruption centres in Tariat, central Mongolia. High-precision analyses of the most fertile Tariat lherzolites are used to evaluate estimates of primitive mantle compositions; they indicate Mg#_PM = 0.890 while lower Mg# in the mantle are likely related to metasomatic enrichments in iron. Within a 10 × 20 km area, and between ~45 and ≥60 km depth, the sampled xenoliths suggest that the Tariat mantle does not show km-scale chemical heterogeneities and mainly consists of residues after low-degree melt extraction at 1–3 GPa. However, accessory (<1%) amphibole and phlogopite are unevenly distributed beneath the eruption centres. Ca abundances in olivine are controlled by temperature whereas Al and Cr abundances also depend on Cr/Al in coexisting spinel. Comparisons of conventional and high-precision analyses obtained for 30 xenoliths show that high-quality data, in particular for whole-rocks and olivines, are essential to constrain the origin of mantle peridotites. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Global photometric analysis of Galactic HII regions

Total infrared fluxes are estimated for 99 HII regions around massive stars. The following wavebands have been used for the analysis: 8 and 24 μm, based on data from the Spitzer Space Telescope(IRAC and MIPS, respectively); 70, 160, 250, 350 and 500 μm, based on data from the Herschel Space Observatory(PACS and SPIRE). The estimated fluxes are used to evaluate the polycyclic aromatic hydrocarbon(PAH) mass fraction(qPAH) and the intensity of ultraviolet emission in the studied objects.It is shown that the PAH mass fraction, qPAH, is much lower in these objects than the average Galactic value, implying effective destruction of aromatic particles in HII regions. Estimated radiation field intensities(U) are close to those derived for extragalactic HII complexes. Color indices [F_(24)/F_8], [F_(70)/F_(24)],[F_(160)/F_(24)] and [F_(160)/F_(70)] are compared to criteria proposed to distinguish between regions of ionized hydrogen and planetary nebulae. Also, we relate our results to analogous color indices for extragalactic complexes of ionized hydrogen.     

Toward development of the 4Dvar data assimilation system in the Bering Sea： reconstruction of the mean dynamic ocean topography

The Bering Sea circulation is derived as a variational inverse of hydrographic profiles（ temperature and salinity） , atmospheric climatologies and historical observation of ocean curents. The important result of this study is estimate of the mean climatological sea surface height （SSH） that can be used as a reference for satellite altimetry sea level anomaly data in the Bering Sea region. Numerical experiments reveal that, when combined with satellite altimetry, the obtained reference SSH effectively constrains a realistic reconstruction of the Amukta Pass circulation.     

Progressive oxidation of pyrite in five bituminous coal samples: An As XANES and Fe Mössbauer spectroscopic study

Naturally occurring pyrite commonly contains minor substituted metals and metalloids (As, Se, Hg, Cu, Ni, etc.) that can be released to the environment as a result of its weathering. Arsenic, often the most abundant minor constituent in pyrite, is a sensitive monitor of progressive pyrite oxidation in coal. To test the effect of pyrite composition and environmental parameters on the rate and extent of pyrite oxidation in coal, splits of five bituminous coal samples having differing amounts of pyrite and extents of As substitution in the pyrite, were exposed to a range of simulated weathering conditions over a period of 17 months. Samples investigated include a Springfield coal from Indiana (whole coal pyritic S = 2.13 wt.%; As in pyrite = detection limit (d.l.) to 0.06 wt.%), two Pittsburgh coal samples from West Virginia (pyritic S = 1.32–1.58 wt.%; As in pyrite = d.l. to 0.34 wt.%), and two samples from the Warrior Basin, Alabama (pyritic S = 0.26–0.27 wt.%; As in pyrite = d.l. to 2.72 wt.%). Samples were collected from active mine faces, and expected differences in the concentration of As in pyrite were confirmed by electron microprobe analysis. Experimental weathering conditions in test chambers were maintained as follows: (1) dry Ar atmosphere; (2) dry O₂ atmosphere; (3) room atmosphere (relative humidity ∼20–60%); and (4) room atmosphere with samples wetted periodically with double-distilled water. Sample splits were removed after one month, nine months, and 17 months to monitor the extent of As and Fe oxidation using As X-ray absorption near-edge structure (XANES) spectroscopy and ⁵⁷Fe Mössbauer spectroscopy, respectively. Arsenic XANES spectroscopy shows progressive oxidation of pyritic As to arsenate, with wetted samples showing the most rapid oxidation. ⁵⁷Fe Mössbauer spectroscopy also shows a much greater proportion of Fe³⁺ forms (jarosite, Fe³⁺ sulfate, FeOOH) for samples stored under wet conditions, but much less difference among samples stored under dry conditions in different atmospheres. The air-wet experiments show evidence of pyrite re-precipitation from soluble ferric sulfates, with As retention in the jarosite phase. Extents of As and Fe oxidation were similar for samples having differing As substitution in pyrite, suggesting that environmental conditions outweigh the composition and amount of pyrite as factors influencing the oxidation rate of Fe sulfides in coal.     

Trace element distribution in peridotite xenoliths from Tok, SE Siberian craton: A record of pervasive, multi-stage metasomatism in shallow refractory mantle

Spinel peridotite xenoliths in alkali basalts at Tok, SE Siberian craton range from fertile lherzolites to harzburgites and wehrlites; olivine-rich (70-84%) rocks are dominant. REE patterns in the lherzolites range from nearly flat for fertile rocks (14-17% cpx) to LREE-enriched; the enrichments are positively correlated with modal olivine, consistent with high-permeability of olivine-rich rocks during melt percolation. Clinopyroxene in olivine-rich Tok peridotites typically has convex-upward trace element patterns (La/Nd_PM < 1 and Nd/Yb_PM ? 1), which we consider as evidence for equilibration with evolved silicate liquids (with higher REE and lower Ti contents than in host basalts). Whole-rock patterns of the olivine-rich xenoliths range from convex-upward to LREE-enriched (La/Nd_PM > 1); the LREE-enrichments are positively correlated with phosphorus abundances and are mainly hosted by accessory phosphates and P-rich cryptocrystalline materials. In addition to apatite, some Tok xenoliths contain whitlockite (an anhydrous, halogen-poor and Na-Mg-rich phosphate), which is common in meteorites and lunar rocks, but has not been reported from any terrestrial mantle samples. Some olivine-rich peridotites have generations of clinopyroxene with distinct abundances of Na, LREE, Sr and Zr. The mineralogical and trace element data indicate that the lithospheric mantle section represented by the xenoliths experienced a large-scale metasomatic event produced by upward migration of mafic silicate melts followed by percolation of low-T, alkali-rich melts and fluids. Chromatographic fractionation and fractional crystallisation of the melts close to the percolation front produced strong LREE-enrichments, which are most common in the uppermost mantle and are related to carbonate- and P₂O₅-rich derivatives of the initial melt. Reversal and gradual retreat of the percolation front during thermal relaxation to ambient geotherm (“retrograde” metasomatism) caused local migration and entrapment of small-volume residual fluids and precipitation of volatile-rich accessory minerals. A distinct metasomatic episode, which mainly produced “anhydrous” late-stage interstitial materials was concomitant with the alkali basaltic magmatism, which brought the xenoliths to the surface.     

Experimental shock metamorphism of the L4 ordinary chondrite Saratov induced by spherical shock waves up to 400 GPa

Abstract– We carried out shock experiments on macroscopic spherical samples of the L4 ordinary chondrite Saratov (natural shock stages S2–S3), using explosively generated spherical shock waves with maximum peak pressures of 400 GPa and shock‐induced temperatures >800 °C (up to several thousands °C). The evolution of shock metamorphism within a radius of the spherical samples was investigated using optical and scanning electron microscopy, microprobe and magnetic analyses as well as Mössbauer spectroscopy and X‐ray diffraction techniques. Petrographic analyses revealed a shock‐induced formation of three different concentric petrographic zones within the shocked samples: zone of total melting (I), zone of partial melting (II), and zone of solid‐state shock features (III). We found a progressive pressure‐induced oxidation of Fe‐Ni metal, whose degree increased with increasing shock peak pressure. The amount of FeO within zone I increased the factor of 1.4 with respect to its amount in the unshocked Saratov sample. This suggests that within zone I about 70 wt% of the initial metallic iron was oxidized, whereas magnetic analyses showed that about 10 wt% of it remained intact. This strongly supports the hypothesis that, in addition to oxidation, a migration of metallic iron from the central heavily shocked zone I toward less shocked peripheral zone took place as well (likely through shock veins where metallic droplets were observed). Magnetic analyses also showed a shock‐induced transformation of tetrataenite to taenite within all shocked subsamples, resulting in magnetic softening of these subsamples (decrease in remanent coercivity). These results have important implications for extraterrestrial paleomagnetism suggesting that due to natural impact processes, the buried crustal rocks of heavily cratered solid solar system bodies can have stronger remanent magnetism than the corresponding surface rocks.     

Accurate estimators of power spectra in N-body simulations

A method to rapidly estimate the Fourier power spectrum of a point distribution is presented. This method relies on a Taylor expansion of the trigonometric functions. It yields the Fourier modes from a number of fast Fourier transforms (FFTs), which is controlled by the order N of the expansion and by the dimension D of the system. In three dimensions, for the practical value   N = 3  , the number of FFTs required is 20.
We apply the method to the measurement of the power spectrum of a periodic point distribution that is a local Poisson realization of an underlying stationary field. We derive an explicit analytic expression for the spectrum, which allows us to quantify – and correct for – the biases induced by discreteness and by the truncation of the Taylor expansion, and to bound the unknown effects of aliasing of the power spectrum. We show that these aliasing effects decrease rapidly with the order N . For   N = 3  , they are expected to be, respectively, smaller than  ∼10⁻⁴  and 0.02 at half the Nyquist frequency and at the Nyquist frequency of the grid used to perform the FFTs. The only remaining significant source of errors is reduced to the unavoidable cosmic/sample variance due to the finite size of the sample.
The analytical calculations are successfully checked against a cosmological N -body experiment. We also consider the initial conditions of this simulation, which correspond to a perturbed grid. This allows us to test a case where the local Poisson assumption is incorrect. Even in that extreme situation, the third-order Fourier–Taylor estimator behaves well, with aliasing effects restrained to at most the per cent level at half the Nyquist frequency.
We also show how to reach arbitrarily large dynamic range in Fourier space (i.e. high wavenumber), while keeping statistical errors in control, by appropriately 'folding' the particle distribution.