Braking index diagnostics of pulsars. I. alignment,Counteralignment and slowing-down noise

We show that the strong correlation observed between the braking indices (n) and the slowing-down ages (Τ) of pulsars is inconsistent with counteralignment between their rotation and magnetic axes, but that the data on pulsars with positive braking indices is consistent with alignment. Alternatively, slowing-down noise can quantitatively account for the data on all pulsars except the Crab and the Vela, and so for the apparent|n| ∼ Τ² correlation observed for the older pulsars.     

Inflationary Solutions for Higher Dimensional Anisotropic Cosmological Model in Scalar-Tensor Theory II

This is the second paper of the series where we have considered Brans-Dicke (B-D) theory as well as general scalar tensor theory of gravitation in higher dimensional space-time model in the false vacuum state. We have examined whether inflationary solutions are possible both for constant or variable coupling parameter ω. Also the nature of the scalar field and the coupling parameter are discussed in the asymptotic limit. This revised version was published online in July 2006 with corrections to the Cover Date.     

Development of limiting soil slope profile under seismic condition using slip line theory

This study embraces the formation of the limiting geometry of finite slopes under the static and seismic conditions within the slip line theory framework coupled with the modified pseudo-dynamic approach. The proposed methodology is expected to achieve a global factor of safety of 1.0 for the obtained slope profile. While analysing the stability of slopes using the limit analysis or the limit equilibrium method, the cognition of the slope geometry and the nature of the slip surface need to be known in advance. Such limitations are ruled out in the present analysis with the aid of the slip line method. Further, by employing the modified pseudo-dynamic approach, the dynamic properties of soil, such as damping ratio and frequency effect, are effectively considered in this stability analysis. The consideration of the slip line theory permits to achieve an adaptive failure mechanism in the analysis. The impact of a set of parameters characterizing the input motion and the dynamic soil properties on the behaviour of a slope explains the relevance of the present modified pseudo-dynamic approach compared to the conventional pseudo-static and the original pseudo-dynamic approaches. The proposed solution serves as a measure of the seismic slope stability in accordance with the geomorphological process generally encountered in nature. Compared with the available literature, the present results propose safe, economical, and efficient design guidelines for finite slopes and intimate the need for preventive measures to enhance the stability of existing slopes.

     

Petrogenesis of ultramafic rocks and olivine-rich troctolites from the East Taiwan Ophiolite in the Lichi mélange

Mineralogy and Petrology - We examine ultramafic and olivine-rich troctolite blocks of the East Taiwan Ophiolite (ETO) in the Lichi Mélange. Although ultramafic rocks are extensively...     

Prioritization of soil conservation measures using erodibility indices as criteria in Sikkim (India)

Erodibility indices are important parameter that can be used to describe the intensity of the soil erosion problems causing environmental concerns. These indices are convenient to estimate the susceptibility to erosion where physical measurement is very difficult. Sikkim is one such state in India where measuring erosion is a tedious process due to its difficult and inaccessible terrain conditions. In the present study, spatial variation of susceptibility of erosion in East district of Sikkim was estimated by using indices such as clay ratio, dispersion ratio, mod clay ratio and critical level of soil organic matter. The result indicates soils in East district are mostly dominated by sand particles (40.5–81.06%) in majority of soil samples. The dispersion ratio values in most of the soils were >15% indicating very high vulnerability to erosion. The values of clay ratio (3.44–9), modified clay ratio (mean value of 6.9) and critical level of soil organic matter content (<5%) indicated high susceptibility to erosion. The trends of indices were generated by IDW interpolation method to understand the spatial variation of the susceptibility to erosion. The interpolated maps were overlaid on subwatershed maps to prioritize the subwatershed for planning treatment measures.     

Influence of Form-Induced Shear Stress on Turbulent Kinetic Energy Budget Distributions Above and Within the Flow-Gravel-Bed Interface in Permeable Gravel Bed Stream—a Comparative Study

Water Resources - Present study aims to illustrate the role of form-induced shear stress on turbulent kinetic energy (TKE) budget distributions in permeable gravel bed streams. In order to achieve...     

Geoenvironmental appraisal of groundwater quality in Bengal alluvial tract,India: a geochemical and statistical approach

Groundwater is an essential natural resource which has enormous use throughout the world, but with the enhanced population pressure, its quality and quantity gets affected. Consequently, assessment and categorization of groundwater quality is necessary and the availability of safe water for utilization is to be ensured. The present study was based on groundwater samples, collected over 5,324 km² from the alluvial tract of Bengal plain, India. Ten geochemical parameters viz. arsenic, pH, total dissolved solids, electrical conductivity, iron, total hardness as calcium carbonate, sulphate, nitrite and depth were analysed, and multivariate statistical analyses were performed on the data set. Factor analysis depicted four factors, which explained 66.57 % of total variability of data. Factor 1 represented high positive loadings on total dissolved solids and electrical conductivity. Factor 2 was associated with depth, arsenic and iron and indicated process of reduction in groundwater. Over extraction of groundwater showed probable relationship with arsenic concentration in groundwater. Parameters of Factor 3 and 4 had been related with agricultural activities and local geological conditions. Further, four clusters observed from hierarchical cluster analysis, assisted in grouping groundwater geochemistry of the region. The results coupled with GIS facilitated in categorizing and mapping the groundwater quality.     

Palaeoenvironmental significance of fluvial facies and archives of Late Quaternary deposits in the floodplain of Damodar River,India

Statigraphic exposures, fluvial archives and borehole data have been allowed to reconstruct the alluvial history of Late Pleistocene to Early Holocene and climate changes in the monsoonal wet–dry region of lower Damodar Basin (West Bengal, India). The facies architectures and climate proxies suggest that five to six climate changes occurred in between ～14 and 6 kiloannum (ka). Supporting evidence from the floodplain of Damodar River demonstrates that the successive phases of aggradation and incision were linked to the south-west monsoonal variability of Late Quaternary period. The onset of semi-arid climate was associated with caliches, pond and backswamp deposits of waning low-energy floods. The relatively warm-humid climate was associated with sandy bedforms, valley fills, slack water deposits and ferruginous nodules. This paper presents a synthesis of the available palaeoclimatic records from the lower Ganga Basin and the rivers of western and central India for the palaeoenvironmental significance of Late Quaternary deposits and discusses the influence of palaeoclimatic controls on the fluvial architectures and archives that developed below the floodplain of Damodar River. We have taken some representative studies from the region to reveal the spatial variability in fluvial successions in response to climate changes during this period.     

Earthquake damage identification: a case study using soft classification approach

The October 8, 2005, Kashmir earthquake (M _w 7.6) affected the rough mountainous regions of India and Pakistan with poor accessibility, and thus, no proper comprehensive ground survey was possible. However, due to the ability of remote sensing technology to acquire spectral measurements of damaged areas at various spatial and temporal scales, extraction of damaged areas can be carried out quickly and with great reliability. The fuzzy-based classifiers [Possibilistic c-Means (PCM), noise cluster (NC), and NC with entropy (NCE)] were applied to identify 2005 Kashmir earthquake, induced landslides, as well as built-up damage (BD) areas, as soft computing approaches using supervised classification. Results indicate that for the identification of landslides and BD areas, NCE classifier generated the best outputs, while for the identification of built-up undamaged areas, NC classifier generated the best output. Further, it was found that the proposed Class Based Sensor Independent (CBSI) technique can improve spectral information of specific class for better identification.     

Delineation of groundwater potential zone in Chhatna Block, Bankura District, West Bengal, India using remote sensing and GIS techniques

Groundwater is one of the most valuable natural resources, which is an immensely important and dependable source of water supply in all climatic regions over the world. Groundwater is in demand in areas where surface water supply is inadequate and nonsexist in the Chhatna Block, Bankura district and is located on the eastern slope of Chotonagpur Plateau, which is mapped on 73 I/15, 73 I/16 and 73 M/3, and falls between latitude 23°10′–23°30′N and longitude 86°47′–87°02′E. It represents plain land and gentle slope, which is responsible for infiltration and groundwater recharge. The groundwater in this region is confined within the fracture zones and weathered residuum. The present investigation is, therefore, undertaken to delineate potential zones for groundwater development with the help of a remote-sensing study. IRS–LISS-III data along with other data sets, e.g., existing toposheets and field observation data, have been utilized to extract information on the hydrogeomorphic features which include valley fills, buried pediment moderate, buried pediment shallow and structural hills, lineament density contour and slope map of this hard rock terrain. The target of this study is to delineate the groundwater potential zones in Chhatna block, Bankura District, West Bengal. Satellite imagery, along with other data sets, has been utilized to extract information on the groundwater controlling features of this study area. Three features (hydrogeomorphology, slope, and lineaments) that influence groundwater occurrences were analyzed and integrated. All the information layers have been integrated through GIS analysis and the groundwater potential zones have been delineated. The weighted index overlay method has been followed to delineate groundwater potential zones. The results indicate that good to excellent groundwater potential zones are available in almost the entire block. The results show that there is good agreement between the predicted groundwater potential map and the existing groundwater borehole databases. The area is characterized by hard rock terrain—still due to the presence of planation surface along valley fills; it became the prospective zone. The area has been categorized into four distinct zones: excellent, good, fair and poor. Excellent groundwater potential zones constitute 30–35 % of the total block area; good groundwater potential zones occupy a majority of the block, covering approximately 55–60 % and the fair potential zones occupy about 10–15 % of the total block. Poor potential zones occupy a very insignificant portion (less than 1 %).