Long-term modulation of cosmic ray intensity in relation to sunspot numbers and tilt angle

A detailed correlative analysis between sunspot numbers (SSN) and tilt angle (TA) with cosmic ray intensity (CRI) in the neutron monitor energy range has been performed for the solar cycles 21, 22 and 23. It is found that solar activity parameters (SSN and TA) are highly (positive) correlated with each other and have inverse correlation with cosmic ray intensity (CRI). The ‘running cross correlation coefficient’ between cosmic ray intensity and tilt angle has also been calculated and it is found that the correlation is positive during the maxima of odd cycles 21 and 23. Moreover, the time lag analysis between CRI and SSN, and between CRI and TA has also been performed and is supported by hysteresis curves, which are wide for odd cycles and narrow for even cycles.     

Distribution of particulate organic carbon in the central Bay of Bengal

Particulate organic carbon (POC) was measured for 77 water samples collected over a 3000 m water column along 88° E in the central Bay of Bengal. The POC values varied from 80 to 895 μg per litre at the surface and 171 to 261 μg per litre at 2000 m. The POC decreased with increasing water depth at all the stations. Deep water concentrations of POC were higher than those reported from other oceanic waters. Distribution of POC was not influenced by water masses. The POC was not significantly correlated with chlorophylla.     

Lethal and sub-lethal effects of chlorination on green mussel Perna viridis in the context of biofouling control in a power plant cooling water system.

Continuous chlorination is a widely followed cooling water treatment practice used in the power industry to combat biofouling. The green mussel Perna viridis is one of the dominant fouling organisms ( > 70%) in the Madras Atomic Power Station. Mortality pattern as well as physiological responses such as oxygen consumption, filtration rate, byssus thread production and faecal matter production of three different size groups of this mussel were studied at different chlorination concentrations. At 0.7 mg l(-1) residual chlorine, 3-4 cm size mussels showed 100% mortality in 553.3 h while 8-9 cm size group mussels died within 588 h. At a relatively high level of residual chlorine (9.1 mg l(-1)), 100% mortality in 3-4 cm and 8-9 cm size groups took 94 and 114 h, respectively. All physiological activities studied showed a progressive reduction as chlorine residuals were increased from 0 to 0.55 mg l(-1). The data indicated that the green mussel can sense a residual chlorine level as low as < 0.15 mg l(-1) and complete valve closure occurs only at 0.55 mg l(-1). The paper also shows that the sub-lethal physiological responses are better indices than lethal responses in planning chlorination strategies.     

Microflares as possible sources for coronal heating

We present a preliminary study of 27 microflares observed by Solar X-ray Spectrometer (SOXS) mission during July 2003 to August 2006. We found that all 27 microflares show the Fe-line feature peaking around 6.7 keV, which is an indicator of the presence of coronal plasma temperature ≥ 9 MK. On the other hand, the spectra of microflares show hybrid model of thermal and non-thermal emission, which further supports them as possible sources of coronal heating. Our results based on the analysis show that the energy relapsed by the microflares is good enough for heating of the active corona. We discuss our results in the light of the hybrid model of microflares production.     

Mapping of iodine,lithium and strontium in oilfield water of Cambay basin,Gujarat

The major oil and gas producing fields in Gujarat are found in Cambay basin. It is known that a huge amount of water is produced with oil and gas production which is called produced oilfield water. Some useful elements (iodine, lithium and strontium) are present with this oilfield water which may be extracted in case of their abundance. The investigation of iodine, lithium and strontium concentrations in produced oilfield water was accomplished by Ion chromatography while for other cations ICP instrument was used. In oilfield water, iodine content ranges from 0.08 to 1.89 mg/l, lithium content ranges from 0.06 to 2.90 mg/l and strontium content ranges from 0.24 to 73.5 mg/l. In addition to above element, Na, Mg, K, Ca, Al, Ba, Fe, Se, Cu, Zn, As, Cd and Hg were also analyzed. The pH and TDS of all the samples were also measured. There is considerable variation in iodine, lithium and strontium in oilfield water samples collected from oil and gas producing fields of Gujarat. There is no definite pattern of variation in iodine, lithium and strontium content.