Chandra smells a RRAT

“Rotating RAdio Transients” (RRATs) are a newly discovered astronomical phenomenon, characterised by occasional brief radio bursts, with average intervals between bursts ranging from minutes to hours. The burst spacings allow identification of periodicities, which fall in the range 0.4 to 7 seconds. The RRATs thus seem to be rotating neutron stars, albeit with properties very different from the rest of the population. We here present the serendipitous detection with the Chandra X-ray Observatory of a bright point-like X-ray source coincident with one of the RRATs. We discuss the temporal and spectral properties of this X-ray emission, consider counterparts in other wavebands, and interpret these results in the context of possible explanations for the RRAT population. B.M.G. acknowledges the support of NASA through LTSA grant NAG5-13023 and of an Alfred P. Sloan Fellowship.     

Evaluation on the change characteristics of ecosystem service in Dhanbad district of Jharkhand,India based on land use change

Ecosystem services (ESs) simply refer to those services conferred by Mother Nature for the survival of her offspring living within. But the provision of ESs is continuously affected by human activity and related changes like transformations in land use and land cover. The present study has been initiated to evaluate the pattern of landscape transformation and its impact on ecosystem service, along with estimating the per capita availability of ESs based on remotely sensed data in the Dhanbad district, Jharkhand, India. The result shows that the total ecosystem service value (ESV) loss of the district was $2251959.76 during 1990–2020. The highest loss of ESV was recorded due to the conservation of agricultural land to built-up area ($15884988.50) and vegetation cover on agricultural land ($14451545.01), while the increased vegetation cover on other types of land helped the district to gain back some balance over the loss. But in a smaller scale study, 5 out of the 8 spatial units are facing negative change in ESV, and unfortunately, they are altogether inhabited by more than 85% of the district's total population. That means the loss of ESV is greater where it needs to be more as per population. Moreover, the per capita ESs in the district decreased by 68.48%, while among the spatial units in Dhanbad it decreased the most (89.60%), which is a serious cause for worry in the future. Therefore, this study can contribute to the process of decision-making, proposing ecological conservation and sustainable development plans for the region.

     

Analysis of eve-teasing potential zones using geospatial technologies and AHP: a study in Midnapore town,West Bengal,India

GeoJournal - Application of geospatial technologies in criminological study is most relevant in present day context. Crime mapping with the help of Geographical Information System is being a very...     

Concentration of polybrominated diphenyl ethers (PBDEs) in sediment cores of Sundarban mangrove wetland, northeastern part of Bay of Bengal (India)

The paper presents the first comprehensive survey of congener profiles (12 congeners) of polybrominated diphenyl ethers (PBDEs) in core sediment samples (<63 microm) covering seven sites in Sundarban mangrove wetland (India). Gas-chromatographic analyses were carried out in GC-Ms/Ms for tri- to hepta- brominated congeners. Results pointed out a non-homogenous contamination of the wetland with summation operator(12) PBDE values ranging from 0.08 to 29.03 ngg(-1), reflecting moderate to low contamination closely in conformity to other Asian aquatic environments. The general order of decreasing congener contribution to the total load was: BDE 47>99>100>154, similar to the distribution pattern worldwide. Although tetrabromodiphenyl ether BDE 47 was found in all samples followed by hexabromodiphenyl ether BDE-154, they were not necessarily the dominant congeners. No uniform temporal trend on PBDE levels was recorded probably due to particular hydrological characteristics of the wetland and/on non-homologous inputs from point sources (untreated municipal wastewater and local industries, electronic wastes from the dump sites, etc.) of these compounds. Because of the propensity of PBDEs to accumulate in various compartments of wildlife and human food webs, evaluation of biological tissues should be undertaken as a high priority.     

Electrical resistivity investigation of the arsenic affected alluvial aquifers in West Bengal,India: usefulness in identifying the areas of low and high groundwater arsenic

This study aims at finding out possible relation between lithology and spatial pattern of dissolved arsenic (As) in groundwater around Chakdaha municipality, West Bengal, India. Satellite image, coupled with electrical resistivity survey and borehole drilling helps to delineate surface and sub-surface lithological framework of the As affected alluvial aquifers. The satellite imagery demonstrate that the high As area are presumably under active flood plain environment (low-lying areas), that constantly receive organics due to periodic flooding. Thick low resistive (fine-grained) layer was observed at the top around the high As areas, which, however, not found in low As areas. The result suggests that hydraulic properties of the surface/sub-surface soil/sediment have an important control on the fate and transport of As in the aquifer. This study demonstrates that electrical resistivity tools can be effectively used for the reconnaissance survey in characterizing the plausible lithological framework of an alluvial aquifer containing As.     

On the aftershock sequence of a 4.6 mb earthquake of the Garhwal Himalaya

Locally recorded data for eighteen aftershocks of a magnitude(m_b) 4.6 earthquake occurring near Ukhimath in the Garhwal Himalaya were analysed. A master event technique was adopted to locate seventeen individual aftershock hypocentres relative to the hypocentre of the eighteenth aftershock chosen as the master event. The aftershock epicentres define an approximately 30 km² rupture zone commensurate with the magnitude of the earthquake. The distribution of epicentres within this zone and the limited amount of first motion data support the view that a group of parallel, sub-vertical, sinistral strike-slip faults oriented N46°, transverse to the regional NW-SE trend of the Garhwal Himalaya, was involved in this seismic episode. Since the estimated focal depth range for aftershocks of this sequence is 3–14 km, we infer that this transverse fault zone extends through the upper crustal layer to a depth of 14 km at least.     

Zur Tektonik der penninischen Zone in der weiteren Umrahmung des nördlichen Dora-Maira-Massivs,italienische Westalpen

Tectonic analysis within the Mesozoic sequence of the Pennine belt in the vicinity of the northern Dora-Maira massif resulted in the discovery of three different B-axes of Alpine age:

1. 1.
   The oldest one with NNW-trending axes is found to have been developed exclusively to the south and west of the Ambin massif, followed by     

Use of terain factors in evaluation and classifications of Darjeeling district,West bengal

The use of LANDSAT data has proved to be a major aid to semi-macroscale geomorphic mapping of terrain. The geomorphological contribution to the classifications of the Darjeeling District, using quantitative measures of selected terrain factors apart from conventional landsystem mapping on MSS-imagery, has been found to be more useful means of terrain evaluation as well as its proper development in resource management. Qualitative estimates of terrain factors, viz. altitude, relief, slope and dissection nature, drainage texture and pattern, valley forms and crest types coupled with landcover types etc. are considered in preparation of landsystem map of the area. Because of its subjective biasness, an alternative approach, the parametric method of terrain classification is carried out to analyse the spatial distributions of quantitative parameters on terrain factors viz. maximum altitude, average altitude, relative relief, average slope, dissection index, drainage density and ruggedness index etc. and to combine the resulting patterns into compositive generalizations. The composite map thus prepared reveals six terrain units of distinct morphological classes and are sufficiently equatable to certain physical conditions of terrain.