Photometric period and rotational brightness modulation of V833 Tau

Photometric data covering 1994–2009, obtained at the Crimean Astrophysical Observatory or retrieved from the ASAS and SuperWASP catalogs, were used to analyze the brightness variations of the rapidly rotating star V833 Tau, whose activity level is close to saturation. Combined with previously published results, these data represent for the first time all stages in the development of the star’s 19- year activity cycle. The photometric period and rotational-modulation amplitude for different epochs are determined, and the qualitative pattern of the spots is considered. The photometric period is close to the orbital period, but always exceeds it, indicating that surface inhomogeneities are located far from the equatorial plane. With the high spottedness of the star, reaching 28% at the cycle maximum, the rotationalmodulation amplitude is 0.05?0.1 ^m , and increases during the growth and decline phases of the 19-year cycle. The rotational modulation is due to spots with higher latitudes than in the case of the Sun, and concentrating on active longitudes.     

Analytical queries on semantic trajectories using graph databases

This article studies the analysis of moving object data collected by location‐aware devices, such as GPS, using graph databases. Such raw trajectories can be transformed into so‐called semantic trajectories, which are sequences of stops that occur at “places of interest.” Trajectory data analysis can be enriched if spatial and non‐spatial contextual data associated with the moving objects are taken into account, and aggregation of trajectory data can reveal hidden patterns within such data. When trajectory data are stored in relational databases, there is an “impedance mismatch” between the representation and storage models. Graphs in which the nodes and edges are annotated with properties are gaining increasing interest to model a variety of networks. Therefore, this article proposes the use of graph databases (Neo4j in this case) to represent and store trajectory data, which can thus be analyzed at different aggregation levels using graph query languages (Cypher, for Neo4j). Through a real‐world public data case study, the article shows that trajectory queries are expressed more naturally on the graph‐based representation than over the relational alternative, and perform better in many typical cases.     

Chemical composition of Russian Arctic precipitation in 2007-2015

The results of observations of the chemical composition of precipitation in the Russian Arctic in 2007-2015 are summarized including the data from NP-35 drifting ice station obtained in 2007-2008 in the framework of the joint program of Arctic and Antarctic Research Institute and Voeikov Main Geophysical Observatory. The qualitative and quantitative difference in the chemical composition of precipitation in the Atlantic, Siberian, and Pacific sectors of the Russian Arctic is revealed. It is found that the concentration of microelements (heavy metals) in precipitation at NP-35 ice station did not exceed 12% of total ions at the lowest mineralization. The comparative analysis is presented of the concentration of sulfate ions in precipitation in Norilsk and at NP-35 ice stations.     

Subpollen Particles as Atmospheric Cloud Condensation Nuclei

Izvestiya, Atmospheric and Oceanic Physics - Bioparticles constitute a significant fraction of atmospheric aerosol. Their size range varies from nanometers (macromolecules) to hundreds of...     

A Method for Obtaining the Nuclear Component in Active Galaxies

We present a new method for the obtention of the nuclear component of active galatic nuclei, that relies on the convolution of a two-dimensional model of the host galaxy, based on seeing-free morphological parameters, with the seeing PSF. The procedure overcomes some limitations of the methods currently in use and does not assume that the nucleus is unresolved. This revised version was published online in July 2006 with corrections to the Cover Date.     

Acute Toxicity of Sodium Nitrite on Channa punctatus (BLOCH) and Mystus (Mystus) vittatus (BLOCH)

This paper deals with the toxicity of sodium nitrite to freshwater fishes, Channa punctatus (BL.) and Mystus (M). vittatus (Bl.) as to determine the acute toxicity. The LC 50 values were obtained by using a static bioassay method for a period of 24, 48, 72 and 96 hour intervals. The LC 50 values of sodium nitrite for C. punctatus were 375, 325, 250 and 200 ppm and for M. (M). vittatus 164, 140, 90 and 64 ppm, respectively. A profuse mucus secretion was evident at higher concentrations as compared to lower ones. The probable causes of mortality of the fishes are also discussed.     

Spatial and temporal variability of hard-bottom macrofauna in a disturbed coastal lagoon (Sacca di Goro, Po River Delta, Northwestern Adriatic Sea)

The sessile and mobile macrobenthos on artificial hard bottoms was studied in 12 stations of the Sacca di Goro lagoon, a brackish, highly stressed water basin in the delta of the river Po, open to the Northwestern Adriatic Sea. Three sampling surveys were carried out in June and September 2000 and June 2001 in order to make three types of temporal comparisons: (i) on a seasonal scale, before and after a summer dystrophic event; (ii) on an annual basis, before and after the works of excavation of a canal through the outer sand bank; (iii) on a multiannual scale, comparing the data with those of a survey carried out in 1988. The biocoenoses did not show large fluctuations after a moderately severe summer dystrophic crisis, while the digging of the canal caused clear changes in the macrobenthos community structure after one year. The long-term comparison showed a shift in the community patterns after a decade.     

An Aerosol Model of the Marine and Coastal Atmospheric Surface Layer

We present a microphysical model for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01–100 µm particles. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of ASDF and its dependence on meteorological parameters, height above sea level (H), fetch (X), wind speed (U) and relative humidity (RH), are investigated. At present, the model covers the ranges H = 0–25 m, U?=?3–18 km s^?1, X?≤?120 km and RH?=?40–98%.

The latest version of the Marine Aerosol Extinction Profiles model (MaexPro) is described and applied to the computation and analysis of the spectral profiles of aerosol extinction coefficients α(λ) in the wavelength band λ?=?0.2–12 µm. MaexPro is based on the aforementioned aerosol model assuming spherically shaped aerosol particles and the well-known Mie theory.

The spectral profiles of α(λ) calculated by MaexPro are in good agreement with observational data and the numerical results obtained from the Navy Aerosol Model (NAM) and the Advanced Navy Aerosol Model (ANAM). Moreover, MaexPro was found to be an accurate and reliable tool for investigating the optical properties of atmospheric aerosols.