Outlier detection with partial information: application to emergency mapping

This paper, addresses the problem of novelty detection in the case that the observed data is a mixture of a known ‘background’ process contaminated with an unknown other process, which generates the outliers, or novel observations. The framework we describe here is quite general, employing univariate classification with incomplete information, based on knowledge of the distribution (the probability density function, pdf) of the data generated by the ‘background’ process. The relative proportion of this ‘background’ component (the prior ‘background’ probability), the pdf and the prior probabilities of all other components are all assumed unknown. The main contribution is a new classification scheme that identifies the maximum proportion of observed data following the known ‘background’ distribution. The method exploits the Kolmogorov–Smirnov test to estimate the proportions, and afterwards data are Bayes optimally separated. Results, demonstrated with synthetic data, show that this approach can produce more reliable results than a standard novelty detection scheme. The classification algorithm is then applied to the problem of identifying outliers in the SIC2004 data set, in order to detect the radioactive release simulated in the ‘joker’ data set. We propose this method as a reliable means of novelty detection in the emergency situation which can also be used to identify outliers prior to the application of a more general automatic mapping algorithm.

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Analysis of magnetovariational response functions

Advances in magnetovariational sounding are stimulating further development of this area of deep geoelectrics. The paper contains a review of magnetovariational response functions revealing their main properties and proposing new methods of their analysis. The theory of magnetic perturbation ellipses having a higher resolution is set forth and methods of the decomposition of magnetovariational functions are discussed that allow one to reduce 3D magnetovariational interpretation to two or three independent 2D inversions and eliminate the effect of 2D regional structures of the geoelectric background.     

Results of the study of anisotropy of elastic properties of rocks from the Luchlompolo fault zone (Pechenga region,Kola Peninsula)

Elastic characteristics of rock samples from the Luchlompolo fault zone taken from outcrop surfaces are compared with elastic characteristics of core samples of the Kola ultradeep borehole taken in an analogous interval. An inversion consisting of a discrepancy between the schistosity levels of rocks in the borehole (below the Luchlompolo fault) and their analogues at the surface (above the fault) is explained by a considerable difference in the force actions that caused the schistosity and layering of rocks in the borehole and at the surface. A kinematic scheme of the fault is constructed, and a hypothesis about the existence of an inversion point (region) in the fault zone and its probable collecting properties is put forward.An inverse dependence of variations in density characteristics of rocks on acoustic dichroism and their elastic anisotropy coefficient for transverse waves is established for the first time.     

Authigenic carbonates in methane seeps from the Norwegian sea: Mineralogy, geochemistry, and genesis

Authigenic carbonates in the caldera of an Arctic (72°N) submarine mud volcano with active CH₄bearing fluid discharge are formed at the bottom surface during anaerobic microbial methane oxidation. The microbial community consists of specific methane-producing bacteria, which act as methanetrophic ones in conditions of excess methane, and sulfate reducers developing on hydrogen, which is an intermediate product of microbial CH₄ oxidation. Isotopically light carbon (δ¹³C_av =−28.9%0) of carbon dioxide produced during CH₄ oxidation is the main carbonate carbon source. Heavy oxygen isotope ratio (δ¹⁸O_av = 5%0) in carbonates is inherited from seawater sulfate. A rapid sulfate reduction (up to 12 mg S dm⁻³ day⁻¹) results in total exhausting of sulfate ion in the upper sediment layer (10 cm). Because of this, carbonates can only be formed in surface sediments near the water-bottom interface. Authigenic carbonates occurring within sediments occur do notin situ. Salinity, as well as CO ₃ ²⁻ /Ca and Mg/Ca ratios, correspond to the field of nonmagnesian calcium carbonate precipitation. Calcite is the dominant carbonate mineral in the methane seep caldera, where it occurs in the paragenetic association with barite. The radiocarbon age of carbonates is about 10000 yr.     

Investigation of magnetic fields in solar active regions

The magnetic-field structure in solar active regions outside spots is studied. The line-of-sight fields were measured using the new Crimean digital magnetograph in three spectral lines—Fe I 5253 Å, Fe II 5234 Å, and Ti I 5193 Å. Observations in the Fe II 5234 Å line indicate systematically higher field strengths than those in the Fe I 5253 Å line. The magnetic fluxes in 2″ elements are ～4.3×10¹⁸ Mx, ～4.6×10¹⁸ Mx, and ～6.2×10¹⁸ Mx according to the Fe I 5253 Å, Ti I 5193 Å, and FeII 5234 Å observations, respectively. Elements 2″–8″ in size make the largest contribution to the magnetic fluxes of active regions outside spots.     

Dynamics and stability of resonant rings in galaxies

We have developed a model for a spheroidal, ring-shaped galaxy. The stars move in a ring with an elliptical cross section at the 1: 1 frequency resonance. The shape of the cross section of the equilibrium ring depends on the oblateness of the galaxy itself, so that the ellipse of the ring cross section is radially extended when the oblateness of the galaxy is small. If the oblateness of galaxy exceeds some critical value, the ellipse cross section is extended along the Ox ₃ axis. The shape of the ring cross section is circular for a galaxy with critical eccentricity. The stability of the ring over a wide range of perturbations is studied. A fundamental bicubic dispersion equation for the frequencies of small oscillations of a perturbed ring is derived. Application of the model to the ring galaxy NGC 7020 shows that its ring cross section should be approximately circular. Analysis of the dispersion equation demonstrates that stellar orbits in the arm are unstable (but the instability increment is small). We conclude that stars in the ring of this galaxy should drift from the 1: 1 resonance, and the ring itself should evolve.     

Anomalous limb darkening in the atmospheres of components of close binary systems with a strong reflection effect

It is shown that in close binary systems of the Algol type, the companions of which are of spectral type K0- K2 and later, there is a temperature inversion in the surface layers of the photosphere and, as a consequence, the angular distribution of the intensity of escaping radiation for individual small areas proves to differ considerably from the limb- darkening law in the spherically symmetrical case. Translated from Astrofizika, Vol. 43, No. 1, pp. 115-121, January–March, 2000.     

Porous dust grains in the shells of Herbig Ae/Be stars

The transfer of polarized radiation in inhomogeneous circumstellar shells with a spheroidal spatial distribution of porous dust particles is computed. The grains are modeled by an MRN mixture of silicate and graphite particles. The optical properties of porous particles (considered separately in the Appendix) are computed by using effective medium theory and Mie theory. The following observational characteristics have been computed for WW Vul, a typical Herbig Ae star with Algol-like minima: the spectral energy distribution from the ultraviolet to the far infrared, the color-magnitude diagrams, the wavelength dependence of linear polarization, and the shell brightness distribution. The effect of grain porosity on the results is considered. It has been found that only moderate particle porosity (the volume fraction of matter is f ～0.5) can explain available observational data in terms of the approach used. Since radiation pressure must rapidly sweep submicron-sized grains out of the vicinity of Herbig Ae/Be stars, we briefly discuss how particle porosity can affect this process.     

A preliminary research on the climatic records of lacustrine deposits of Qingtu Lake in the last 6000 years

１　ＳＴＵＤＩＥＤＲＥＧＩＯＮＡＮＤＡＮＡＬＹＳＩＳＭＥＴＨＯＤＬｏｃａｔｅｄａｔｎｏｒｔｈｗｅｓｔｅｒｎｍａｒｇｉｎｏｆＴｅｎｇｇｅｒＤｅｓｅｒｔａｎｄ７０ｋｍｎｏｒｔｈｅａｓｔｏｆＭｉｎｑｉｎＣｏｕｎｔｙｉｎＧａｎｓｕＰｒｏｖｉｎｃｅ,ＱｉｎｇｔｕＬａｋｅｂｅｌｏｎｇｓｔｏｔｈｅＳｈｉｙａｎｇＲｉｖｅｒＤｒｙＤｅｌｔａ,ａｎｄｔｈｅａｌｔｉｔｕｄｅｉｓ１２９２－１３１０ｍ．Ｔｈｅｒｅｇｉｏｎｈａｓｔｈｅｃｈａｒａｃｔｅｒｏｆｔｅｍｐｅｒａｔｅｃｏｎｔｉｎｅｎｔａｌａｒｉｄｄｅｓｅｒｔｃｌｉ…     

The pattern,evolution, and mechanism of venture capital flows in the Guangdong-Hong Kong-Macao Greater Bay Area,China

As an important innovation flow, venture capital has been examined in urban network research. However, the segmentation of capital categories and the cross-scale connection of capital remain scarcely analyzed. This study focuses on the structure and industry differentiation of venture capital flows in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA) and its cross-scale network characteristics. Based on a venture capital database covering capital amount, investment subject address information,...