Thermal-convective instability of a composite rotating stellar atmosphere in the presence of a variable magnetic field

The thermal-convective instability of a composite stellar atmosphere is considered in the presence of rotation, variable horizontal magnetic field, and collisional effects. The criteria for monotonic instability are obtained which generalize the criterion derived for thermal-convective instability in the absence of above effects.     

Sources of SEP Acceleration during a Flare – CME Event

A high-speed, halo-type coronal mass ejection (CME), associated with a GOES M4.6 soft X-ray flare in NOAA AR 0180 at S12W29 and an EIT wave and dimming, occurred on 9 November 2002. A complex radio event was observed during the same period. It included narrow-band fluctuations and frequency-drifting features in the metric wavelength range, type III burst groups at metric – hectometric wavelengths, and an interplanetary type II radio burst, which was visible in the dynamic radio spectrum below 14 MHz. To study the association of the recorded solar energetic particle (SEP) populations with the propagating CME and flaring, we perform a multi-wavelength analysis using radio spectral and imaging observations combined with white-light, EUV, hard X-ray, and magnetogram data. Velocity dispersion analysis of the particle distributions (SOHO and Wind in situ observations) provides estimates for the release times of electrons and protons. Our analysis indicates that proton acceleration was delayed compared to the electrons. The dynamics of the interplanetary type II burst identify the burst source as a bow shock created by the fast CME. The type III burst groups, with start times close to the estimated electron-release times, trace electron beams travelling along open field lines into the interplanetary space. The type III bursts seem to encounter a steep density gradient as they overtake the type II shock front, resulting in an abrupt change in the frequency drift rate of the type III burst emission. Our study presents evidence in support of a scenario in which electrons are accelerated low in the corona behind the CME shock front, while protons are accelerated later, possibly at the CME bow shock high in the corona.     

A limit on the number density of bright z≈ 7 galaxies

We present a survey of bright optical dropout sources in two deep, multiwavelength surveys comprising 11 widely separated fields, aimed at constraining the galaxy luminosity function at   z ≈ 7  for sources at  5–10  L * ( z = 6)  . Our combined survey area is 225 arcmin² to a depth of   J _AB= 24.2  (3σ) and 135 arcmin² to   J = 25.3  (4σ). We find that infrared data longwards of 2 μm are essential for classifying optical dropout sources, and in particular for identifying cool Galactic star contaminants. Our limits on the number density of high-redshift sources are consistent with current estimates of the Lyman break galaxy luminosity function at   z = 6  .     

Effect of linear waves on kinetic Alfvén wave localization and turbulent spectrum

We have presented the localization of kinetic Alfvén wave (KAW) in intermediate β plasma (m _e /m _i ?β?1) by developing a model based on pump kinetic Alfvén wave and finite amplitude magnetosonic fluctuations. When KAW is perturbed by these background magnetosonic fluctuations, filamentary structures of KAW magnetic field are formed. First, a semi analytical model based on paraxial approximation has been developed to understand this evolution process. Localized structures and magnetic fluctuation spectrum of KAW has also been studied numerically for finite frequency of KAW. The calculated magnetic fluctuation spectrum follows two types of scalings. Above the proton gyroradius scale lengths (in inertial range), spectrum follows Kolmogorovian scaling. Below this scale dispersion starts and the spectrum steepens to about \(k_{x}^{-2.5}\) . The result shows the steepening of power spectra which can be responsible for particle acceleration in solar wind due to the energy transfer from larger to smaller lengthscales. Obtained magnetic turbulent spectra are consistent with observations of Cluster spacecraft in solar wind.     

Anthropogenic platinum,palladium and rhodium concentrations in road dusts from Hyderabad city,India

This paper presents the first study of accessing the Pt, Pd and Rh levels in road dusts collected from Hyderabad city, India, as these metals, emitted from automobile catalytic converters, are accumulating in the environment causing concern about human health and ecological risks. Samples were analyzed by ICP-MS following preconcentration by NiS-fire assay and Te coprecipitation. Pt (1.5–43 ng/g), Pd (1.2–58 ng/g) and Rh (0.2–14.2 ng/g) concentrations obtained were above upper crust values, but were lower when compared with several other cities around the world. Dust samples from road junctions and traffic signals with heavy and erratic traffic flow showed higher PGE levels than those from roads with low and free flow traffic suggesting that traffic flow conditions greatly influenced emission of PGE from the catalyst. Significant correlation of Pt, Pd and Rh indicate a common source for these metals. PGE were also positively correlated with Ce, Zr, Hf and Y. These positive inter-element correlations identified traffic as the main source of PGE emission to the roadway environment. The results obtained indicate to an appreciable increase in auto catalyst-derived PGE. In consideration of the adverse effects of PGE, monitoring their level and transformation paths is of prime importance.     

Nitrate pollution of groundwater in Toyserkan,western Iran

A total of 95 groundwater samples were collected from Toyserkan, western Iran to assess the chemical composition and nitrate (NO₃ ⁻) status of groundwater. The most prevalent water type is Ca–HCO₃ followed by water types Ca–Mg–HCO₃. In comparison with the World Health Organization (WHO) drinking water guideline of 50 mg l⁻¹ for NO₃ ⁻, a total of nine wells (9.5%) showed higher concentrations. In 36% of samples (34) NO₃ ⁻ concentration was low (<20 mg l⁻¹), and in 53.7% of samples (51), in the range of 20–50 mg l⁻¹. The samples were classified into four groups based on NO₃ ⁻ and chloride (Cl⁻) concentrations. Of the samples, 40% were classified as group 4 and were relatively high in Cl⁻ and NO₃ ⁻ (Cl⁻ > 47 mg l⁻¹, NO₃ ⁻ > 27 mg l⁻¹). The high correlation between NO₃ ⁻ and Cl⁻ (r = 0.86, p < 0.01) is consistent with a manure source, resulting from the practice of adding salt to animal feed. Pollution of groundwaters appeared to be affected by the application of inorganic fertilizer at greater than agronomic rates, Cl-salt inputs, and irrigation practice.     

Geochemical characteristics and evaluation of minor and trace elements pollution in groundwater of Tuticorin city,Tamil Nadu,India using geospatial techniques

In this work the major and trace elements pollution levels in groundwater of Tuticorin city of Tamil Nadu was investigated. This coastal city with numerous large and small scale industries has increasingly affected the water quality by dumping effluents. The mean major and trace elements levels in groundwater in descending order: Si > Sr > Zn > Fe > Rb > Se > Al > Mn > Cu > As > Cr > Ba > V > Ni > Pb > Mo > Co > Sb > Cd > Ag. The concentrations of As, Se, Pb, Ba, Al, Fe and V (0.084, 0.150, 0.057, 0.837, 0.357 and 0.052) in some of the groundwater samples exceed the standard value of world health organization (WHO, 2004). Interrelationship between the elements was done by correlation matrix and factor analysis which indicates the contribution from industrial and irrigation fields. Spatial interpolation of inverse distance method (IDW) maps of all the elements suggested that discharge of effluents from chemical factory (STERLITE, TAC, SPIC, HEAVY WATER PLANT, NILA SEA FOODS), municipal wastewater, fertilizers were added to the natural sources. Results of this research suggests that proper measures should be taken to protect the vital groundwater resources in the Tuticorin city.     

Geochemistry and Metallogeny of Phosphorus in the Russian Platform during the Jurassic–Cretaceous

The composition and metallogeny of igneous rocks and relevant weathering crusts of Jurassic–Cretaceous provenances of the Russian Platform are considered. It is shown that the association of metals that accumulated in the process of weathering and erosion of ancient substratum includes P, Fe, Ti, V, and Cr. This process is reflected in the formation of nodular phosphorites, Ti and Zr placers, and iron ore deposits in the Jurassic–Cretaceous seas of the platform.     

Al hematites prepared by homogeneous precipitation of oxinates: material characterization and determination of the Morin transition

A novel method for synthesis of aluminium hematites, based upon the homogeneous precipitation of Fe and Al oxinates in various proportions, is presented. The precursor precipitates are heated in air at 700?°C. X-ray diffraction, thermal analyses, BET, FTIR, optical reflection analysis, TEM and Mössbauer spectroscopy at room temperature and 80?K of the resulting products indicate that single-phase hematites are formed with structural Al substitution of up to 10 at%. Interestingly, the particle size (>100?nm) is not substantially reduced by the Al content. Although it remains difficult to obtain a homogeneously distributed Al substitution in the final hematite, this processing line offers a unique opportunity to separate the effects of grain size and Al substitution on the Morin transition temperature (T _M) of Al hematite. From the comparison between the present hematites and a series of Al-substituted hematites with lepidocrocite as precursor, it could be shown that the effect on T _M, associated with a change of a factor 10 in grain size, is about 1/3 of the effect caused by a change of 10 in the degree of substitution. Finally, it is suggested that proper thermal treatments under different conditions of the same precursors are likely to produce spinel phases.     

Cyclic inelastic behavior and analytical modelling of pile–leg interaction in jacket type offshore platforms

Structures in locations susceptible to severe seismic disturbances should be designed properly in order to resist lateral forces induced by earthquake motions. Steel offshore platforms are some of those structures which are built to withstand environmental and accidental loads during oil exploitation operation. Particular attention is being paid to earthquake loads in seismic active areas because it directly influences the capacity of the offshore installations.

In this paper, a small-scaled planar platform has been modelled analytically using nonlinear finite element program, based on an experimental test, conducted simultaneously in order to assess the local and global behavior of pile–leg interaction in Jacket Type Offshore Platforms (JTOPs). A combination of nonlinear beam column elements and fatigue affected elements are used to capture the inelastic cyclic behavior of planar frame as accurately as possible. Results of analytical tests are to be compared with experiments and it is concluded that an analytical approach can be best used for modelling JTOPs with reasonable accuracy regardless of the type and scale of the structure. Moreover, a special study on joints has been carried out and the best model has been selected to simulate brittle behavior of joints resulting from heat affected zone.