Finite element computation of pollutant transport in thermally stratified flows

A finite element model for the computation of thermally stratified flows is described. The model includes a special treatment of the pressure gradient term by splitting it into hydrostatic and hydrodynamic contributions. Four-node elements are used for space-discretization and a semi-implicit scheme for time integration. The computed flow is used to simulate pollutant transport by a finite element model. Numerical results from such simulations, in particular for urban heat islands are described and compared with experimental data.     

Seed biology of Australian arid zone species: Germination of 18 species used for rehabilitation

Revegetation of disturbed land, particularly in arid environments, is often hindered by low seedling establishment. Information on seed biology and germination cues of keystone species is lacking, particularly in arid Australia; a major zone for mining developments. This study investigated seed characteristics and germination of 18 common species required for rehabilitation of disturbed areas at Shark Bay Salt in the Shark Bay World Heritage Area, Western Australia. Untreated seeds of seven species (Aphanopetalum clematideum, Atriplex bunburyana, Austrostipa elegantissima, Melaleuca cardiophylla, Pembertonia latisquamea, Rhagodia baccata, Salsola tragus) exhibited high germination percentages. Seeds of two species (Acacia tetragonophylla, Stylobasium spathulatum) had low imbibition, which increased with hot-water treatment, hence require scarification for germination. Gibberellic acid, smoke water and karrikinolide (a butenolide isolated from smoke) substantially increased germination percentages of three species (Anthocercis littorea, Diplolaena grandiflora, Solanum orbiculatum). Seeds of the remaining six species (Dioscorea hastifolia, Eremophila oldfieldii, Nitraria billardierei, Ptilotus exaltatus, Thryptomene baeckeacea, Zygophyllum fruticulosum) had low germination percentages regardless of treatment. Most species germinated equally well at 26/13 °C and 33/18 °C, however seven species had improved performance at 26/13 °C. This study is significant to land managers and conservation agencies with an interest in optimising germination of arid zone seeds for restoration.     

Variability of the Blazar 4C 38.41 in 2006–2017

The results of multicolor photometric and polarization observations of the blazar 4C 38.41 (Q 1633+382) performed at St. Petersburg State University, the Pulkovo Astronomical Observatory of the Russian Academy of Sciences, Boston University, and Steward Observatory in 2006–2017 are analyzed. Separate variable sources responsible for the observed activity are distinguished, whose power-lawspectra and high degree of polarization confirm their synchrotron nature. The observed color variability of the object (redder when brighter) can be explained by an increase in the contribution to the total emission of a red component with variable flux and a constant relative spectral energy distribution. A close correlation between the optical and gamma-ray light curves is identified, suggesting the same location of the variable sources responsible for the radiation in these bands.

     

The effects of integrals on the totality of solutions of dynamical systems

Regions of possible motions are established for dynamical systems possessing time-independent Hamiltonians or for systems which are reducible to that form by means of integrals of the motion using only extended point transformations. The method is applied to the problem of three bodies in a plane and surfaces of zero velocity are found. The governing parameters are the energy, angular momentum and the masses of the participating bodies. The analytical and geometrical properties of these surfaces provide qualitative results for given constants of the motion.     

Power spectrum of brightness temperature fluctuations derived from solar eclipse observations at 2.8 GHz

In this paper we report on the MEM power spectrum analysis of brightness temperature fluctuations observed at 2.8 GHz during the total solar eclipse of 16 February 1980. The observed periodicities range from 3.5 min to 64 min. These periodicities may arise due to spatial and/or temporal variations in the solar radio emission. The observed periodicities imply presence of scale sizes ranging from 70,000 to 600,000 km assuming that the brightness fluctuations arise because of spatial variation only. On the other hand, if these fluctuations are due to temporal variation, the observed periodicities correspond well to predicted modes of solar global oscillations.     

Normalization of Hydrodynamic Coefficients in Morison Equation

-The hydrodynamic coefficients C_d and C_m are not only dependent on the size of slender cylin-der,its location in water,KC number and Re number,but also vary with environmental conditions,i.e.,in regular waves or in irregular waves,in pure waves or in wave-current coexisting field.In this paper,thenormalization of hydrodynamic coefficients for various environmental conditions is discussed.When aproper definition of KC number and proper characteristic values of irregular waves are used,a unified re-lationship between C_d,C_m and KC number for regular waves,irregular waves,pure waves and wave-cur-rent coexisting field can be obtained.     

Glutathione S-transferase from an antarctic fish, Dissostichus mawsoni

Glutathione S-transferase activity was measured in the hepatic cytosol front Dissostichus mawsoni and Pagothenia borchgrevinki. Activity measures with 1-chloro-2,4-dinitrobenzene as substrate were 11·2 and 16·7 μmol/min/g tissue respectively. Little or no activity was detected when p-nitrobenzyl chloride or 3,4-dichloro-1-nitrobenzene were used as substrate. The hepatic glutathione S-transferases from D. mawsoni were partially purified using gel filtration and chromatofocusing. Three peaks of activity were resolved. The major isozyme (158-fold purification) eluting at pH7·1 appeared to be catalytically a homodimer. The isozyme was highly inhibited by triphenyltin chloride (IC₅₀ = 0·1 μ) while inhibition constants for Cibicron Blue 3GA, bromosulphophalein and hematin were 1·1, 20 and 34 μ respectively.