Cylindrical blast wave from wire explosion

The blast wave produced by an explosion of wire under the influence of a magnetic field has been studied in this paper. Conductivity of the gas is assumed to be infinite. Numerical integration has been performed using the Runge-Kutta method and the distribution of flow variables behind the shock wave is shown graphically.     

ST Persei: A possible multi-body system

Detailed period study of the eclipsing binary ST Per is presented. A new period (P=2^d.648339) is given. Period changes in different portions of the O-C diagram with a new period have been estimated. The total changes in period (P) ranges from 2.17×10^–5d to 2.64×10^–4d which is appreciably large. Sufficient number of minima in the time interval 1934 to 1985 for this system are available. Distinct increasing and decreasing trends are evident, the change in the tendency appears to have occurred around 1947. Sinusoidal variation is seen between cycles 7000–10000, which indicates that ST Per is a three-body system, the period of the third body being about 22 years. However, the sinusoidal variation is not perfectly symmetric in shape, therefore, it is suspected that ST Per is a four-(or multi-) body system.     

On the Length-Weight Relationship of the Ganga River Prawn Macro-brachium birmanicum choprai (TIWARI)

A total of 331 male and 237 female individuals of the Ganga river prawn, Macrobrachium birmanicum choprai (TIWARI), were examined to establish relationship between its length and weight. The individuals of both the sexes were placed separately in different size groups. When plotted against corresponding values of weight, the average length computed for each size group exhibited an exponential relationship. However, the logarithimic values of observed lengths when plotted against corresponding values of weight exhibited a linear relationship. Correlation coefficient values for both the sexes were found highly significant (r = 0.9846 for males and 0.9762 for females).     

Discovery of <Emphasis Type="Italic">Elephas</Emphasis> cf. <Emphasis Type="Italic">namadicus</Emphasis> from the late Pleistocene strata of Marginal Ganga Plain

We describe an elephant skull recovered from a cliff section of Dhasan river of Marginal Ganga Plain. The dental morphology and cranial features of the skull have been compared with the known species of Elephas from the Indian subcontinent. Although it shows very near resemblance to Elephas namadicus, but being an isolated specimen its specific identity cannot be proclaimed with certainty. As such, the specimen is provisionally referred as E. cf. namadicus. The Optically Stimulated Luminescence ages place this find at ~56 ka BP. This is the first chronologically well constrained report of E. cf. namadicus from the Ganga Plain.     

Intercomparison of High-Resolution Bay of Bengal Circulation Models Forced with Different Winds

The high-resolution Bay of Bengal circulation modeling in the region [80E–95E; 5N–22N] is performed with a horizontal resolution of 10 km and the highest vertical resolution of 5 m near the surface. The intercomparison experiments, with ocean model forced with the near-surface (1) National Centers for Environmental Prediction (NCEP) reanalysis winds and (2) blended seawinds data (a combination of remotely sensed scatterometer and in situ observations) are carried out for a period of 17 years during 1998–2014. The seasonal variability of the realistically simulated surface hydrographic (temperature and salinity) and circulation (currents) variables from both the experiments is compared and contrasted with the observational data. The mixed layer depth seasonal variability of the region is also studied. The mesoscale features of currents at 50 and 100 m are also studied. The volume transport across different sections in the Bay of Bengal is computed and its relation with summer monsoon rainfall is investigated. The results suggest that there is no real advantage of using high-resolution blended seawinds over the much coarser NCEP reanalysis winds.     

Origin of the marine magnetic quiet zones in the Labrador and Greenland Seas

The central part of the northern Labrador Sea is a magnetic quiet zone, and is flanked by regions exhibiting well developed linear magnetic anomalies older than anomaly 24. The quiet zone dies out progressively to the south, where it becomes possible to correlate anomalies between adjacent profiles. A 45 degree change in spreading direction at anomaly 25 time was accompanied by a major jump in ridge position and orientation. As a consequence of this reorganisation, spreading in the northern Labrador Sea next occurred within a rift that was oriented at 45 degrees to the spreading direction, while to the south spreading occurred within in a rift that was orientated at 90 degrees to the spreading direction. Obliquity of spreading changed, between these limits, progressively along the ridge. The quiet zone may be present to the north because the oblique northern geometry resulted in a fragmented ridge composed of many small-offset transform faults joining many short spreading ridge segments. Each magnetic source block produced by magnetisation of sea floor at these small ridge segments will be surrounded by similar small blocks that have opposite polarity, so that none can be resolved at the sea surface. Supporting evidence comes from multi-channel seismic profiles across the Labrador Sea, which show that the basement is more textured within the quiet zone than outside, suggesting the presence of numerous small fracture zones in the quiet zone.A magnetic quiet zone is present in the northern Greenland Sea between margins that are oblique to the spreading direction. In contrast, there are clear lineated magnetic patterns in adjacent areas to north and south where the margins are orthogonal to the spreading direction. This quiet zone may also be due to the geometry of spreading.     

Period variation of BZ Eridani

We find that the Chandrasekhar-Kendall functions (A) do not satisfy the identity (A·)A=(×A)×A+1.2A² and, therefore, the results, in magnetohydrodynamics and other fields, obtained by two independent authors may differ from one another.