Nitrogen isotopes in chondrules: signatures of precursors and formation processes

Nitrogen isotope abundance of 68 individual chondrules separated from six ordinary, two carbonaceous and two enstatite chondrites has been analysed. N composition of chondrules from ordinary and carbonaceous chondrites generally shows large variation and differs from that of their host. This large range of N composition suggests the presence of different N components in their precursors. Chondrules from the enstatite chondrites on the other hand show N isotopic composition similar to that of their host, suggesting precursors with similar N components for both chondrules and their host meteorites. Nitrogen isotopic systematics therefore distinguishes chondrules in enstatite chondrites from those in ordinary and carbonaceous chondrites. Chondrules in ordinary and carbonaceous chondrites require precursors that are different from those of their parent meteorites and formation in nebular environment, whereas chondrules in enstatite chondrites are formed from the same precursors as those of their host chondrites and presumably in the same region

Nitrogen in stone meteorites and terrestrial standards

Nitrogen contents have been determined by neutron activation method in stone meteorites and silicate standards. Leaching and sieving experiments on standards indicate that contamination from atmospheric nitrogen is negligible. For BCR-1 nitrogen contents show a range from 15 to 62ppm. The study includes 32 chondrites belonging to various classes and six achondrites. Nitrogen is high in C1 and C2 chondrites (500 to 1,000ppm) and in E chondrites (100 - 500ppm). C3 group shows variable amounts of nitrogen. Ordinary chondrites have similar nitrogen contents (~30pm) irrespective of their petrologic group. For all classes of meteorites, chondrules have lower nitrogen compared to the matrix. Dark phases of some gas- rich meteorites are enriched in nitrogen as compared to their light counterparts. Non-magnetic portions have slightly excess N compared to the magnetic portions. Correlation of N with C, In, Bi, Tl, Zn and Cd indicates the presence of two host phases for N

Water characteristics, mixing and circulation in the Bay of Bengal during southwest monsoon

Influence of the freshwater influx, the wind forcing and the Indian Ocean monsoon drift current on the property distributions and the circulation in the Bay of Bengal during southwest monsoon has been quantified. At the head of the Bay, waters of low salinity, affected by the freshwater influx, occupy the upper 90 m water column. The isohaline 34.0 × 10−3 separating these waters from those of underlying saline waters shoals southward gradually and outcrops around 14N, 10N and 6N in the western, central and southeastern regions of the Bay respectively. The wind-stress-curl-induced upwelling effect is confined to depth limits of 50–100 m as is supported by a band of cold (24°–19°C) water in the central Bay. In the southern and central regions of the Bay, the monsoon drift current feeds the large scale cyclonic gyre apart from maintaining the northward flowing boundary current in the eastern Bay. A warm (27°–23°C), saline (35.0–35.2 × 10−3) watermass is advected northeastward along with the monsoon drift current into the Bay up to 14N at the depth limits of 50–100 m. Below this depth, in the western Bay a well-defined southward flow in the form of a boundary current is documented. Intense vertical mixing is inferred at the zones of salinity fronts in the depth limits of 40–100 m and also at deeper depths (\u3e 2200 m) and elsewhere lateral mixing is predominant

Kinetics of Oxidation of Methyl Orange & Methyl Red by V(V)*

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Studies of upwelling along the West Coast of India using geopotential anomaly

As summer is the season of mixing: and winter the season of stratification in the Arabian Sea along the west coast of India, summer minus winter dynamic depth. which takes into account the integrated effects of temperature, salinity and pressure is considered to reveal regional differences of the intensity of upwelling: relative to winter situation. The areas of intensive upwelling a r e thus identified. Stabilities of water layers during summer are examined with respect to those during winter

Total nitrogen in Luna-24 samples

Total nitrogen has been measured by neutron activation in three Luna-24 soils. The nitrogen abundances are found to vary from 46 ppm to 65 ppm with no significant variation with stratification. From the low nitrogen content of these soils, it is concluded that the Luna-24 soils studied in this work are immature

Measurement of Orbital Decay in the Double Neutron Star Binary PSR B2127+11C

We report the direct measurement of orbital period decay in the double neutron star pulsar system PSR B2127+11C in the globular cluster M15 at the rate of $(-3.95 \pm 0.13) \times 10^{-12}$, consistent with the prediction of general relativity at the $\sim 3$ level. We find the pulsar mass to be $m_p = (1.358 \pm 0.010) M_\odot$ and the companion mass $m_c = (1.354 \pm 0.010) M_\odot$. We also report long-term pulse timing results for the pulsars PSR B2127+11A and PSR B2127+11B, including confirmation of the cluster proper motion.Comment: 12 pages, 4 figures, accepted for publication in ApJ

Vulnerability from storm surges and cyclone wind fields on the coast of Andhra Pradesh, India

The results presented here are from a study conducted for the government of the state of Andhra Pradesh (GOAP) in India, as part of a World Bank project on cyclone mitigation. A set of detailed maps were prepared depicting the Physical Vulnerability (PV), specifically storm surge inundation zones are shown for frequent occurrence, 50-year return period, likely scenario for global warming and extreme global warming. Similarly vulnerable areas from strong wind field from tropical cyclones (TCS) are also presented for the same four parameters. Vulnerability zones are presented from a social point of view also based upon certain socio-economic parameters that were included in determining the overall vulnerability of each Mandal in a coastal district (a Mandal represents a group of villages and towns) include: population, senior citizens, women, children under different age groups, type of housing, income level, cyclone shelters, hospitals and medical centres, schools and caste based population. The study is about scenarios that could happen if global warming and the predicted intensification of TCS actually occur as predicted by some numerical models

Salinity changes in the estuary and the coastal sea adjacent to the portmouth at Cochin

The article deals with the details of salinity changes in the Cochin estuary and its influence and interrelations with the Vembanad lake

Ecology of mudbanks - Hydrography

The variations in physical and chemical parameters of the Alleppey mudbank waters are discussed in this paper. The fluctuations in tem perature, salinity, oxygen and the comparatively high nutrient contents of the mudbank waters are highlighted