Model experiments showing simultaneous development of folds and transcurrent faults

Simultaneous development of noncylindrical folds and transcurrent fractures has been studied using model techniques. A plasticine model was compressed in one direction and an initial formation of folds was followed by the initiation of conjugate sets of transcurrent fractures. It was recorded that with progressive deformation the length of each fracture and the displacement along it increase steadily and the rate of displacement varies at different stages of deformation. Individual fold geometries vary along their hinge lines and these geometrical variations appear to be due to interference of folds with the transcurrent fractures. These interference effects also change the amount of rotation of fractures. Fold structures are different on either side of the fault plane. A natural example from the Bude area, England, shows similar geometrical features.The method of determining fault displacement by comparing the positions of fold hinge lines on either side of a fault is discussed in the light of the above results.     

Deciphering Groundwater Flow Systems in Oasis Valley, Nevada, Using Trace Element Chemistry, Multivariate Statistics, and Geographical Information System

The origin of groundwater discharging via evapotranspiration and from springs within Oasis Valley, Nevada, is of concern owing to the close proximity of the Nevada Test Site (NTS) and the possible contamination of groundwater as a result of underground nuclear testing. Principal components analysis, cluster analysis, and population partitioning, along with a Geographical Information System, were used to decipher groundwater flow patterns in Oasis Valley, Nevada. These multivariate statistical techniques were applied to the trace element chemistry of groundwater samples collected from 26 springs and wells within Oasis Valley, the NTS, and the Nellis Air Force Range. The results of all statistical analyses showed similar geographical trends in the trace element chemistry of the groundwaters included in this study. Differences are observed between the groundwaters from the NTS and those of Oasis Valley based on the concentrations of the elements Li, Ge, Mo, Rb, Ba, U, and Ru. A concentration gradient is observed from lower concentrations in the NTS to increasing concentrations toward Oasis Valley suggesting groundwater flow in an overall southwestward direction from the NTS. Also, a different trace element signature is observed for the waters collected in the northern and western region of Oasis Valley, suggesting another source of groundwater to this area.     

Soil Carbon and Nutrient Accumulation under Forest Plantations in Jharkhand State of India

The decrease and degradation of the tropical forests affect not only the production of timber but also the global environment in a large scale. The ability of soil to sustain and its supply of nutrients to a growing forest are controlled by a complex of biogeochemical processes. The purpose of the present study aims to assess the degraded forest fringe areas, to promote plantations of various types and to evaluate their impacts on the soil nutrients and carbon content accumulation. The soil organic carbon (SOC) and nutrient content were evaluated and compared between plantations of mixed native species (MNS), some native tree species as Shorea robusta, Dalbergia sissoo, Dendrocalamus spp., certain agro‐forestry species and some exotic varieties. The impacts of the plantations on the SOC and the nutrients were firstly analyzed through comprehensive chemical analyses and the results were compared with the soil samples collected prior to plantation forestry. Significant changes were observed in SOC content, in nutrients, and in amounts of exchangeable cations. Soil carbon levels were highest under the MNS, Dendrocalamus and Tectona grandis stands and lowest under D. sissoo and Terminalia arjuna. Total N showed highest levels under Dendrocalamus and Pongamia pinnata and significantly higher in stands of native species; lowest total N level was observed in D. sissoo plantations. The C/N ratios of the soil varied between 9.2 and 13.5 among the exchangeable cations. Ca²⁺ recorded the maximum levels and Na⁺ showed the lowest levels.     

Growth and decay of sonic waves in thermally radiative magnetogasdynamics

The propagation of weak discontinuities headed by a wavefront and their formation into shock waves are investigated in a thermally-radiative ideal plasma. It is found that all compressive waves grow without bound only if the magnitude of initial discontinuity associated with the wave exceeds a critical value. In particular, the grow and decay of weak discontinuities in plane, cylindrical, and spherical geometries have been discussed and the shock formation distance and time in all these cases have been derived in presence of magnetic field and radiation, separately.     

Micromixing modelling of concentration fluctuations in inhomogeneous turbulence in the convective boundary layer

The micromixing technique, widely used in engineering calculations of mixing and chemical reaction, is extended to atmospheric boundary-layer flows. In particular, a model based on the interaction-by-exchange-with-the-conditional-mean (IECM) micromixing approach is formulated to calculate concentration fluctuation statistics for a line source and a point source in inhomogeneous and non-Gaussian turbulence in the convective boundary layer. The mixing time scale is parameterised as a linear function of time with the intercept value determined by the source size at small times. Good agreement with laboratory data for the intensity of concentration fluctuations is obtained with a value of 0.9 for the coefficient of the linear term in the time-scale parameterisation for a line source, and a value of 0.6 for a point source. Calculation of higher-order moments of the concentration field for a line source shows that non-Gaussian effects persist into the vertically well-mixed region. The cumulative distribution function predicted by the model for a point source agrees reasonably well with laboratory data, especially in the far field. In the limit of zero mixing time scale, the model reduces to a meandering plume model, thus enabling the concentration variance to be partitioned into meandering and relative components. The meandering component is shown to be more persistent for a point source than for a line source.     

Supernovae and the Ap phenomenon

We put forward evidence that relates the phenomenon of the chemically peculiar stars of the upper main sequence to Supernovae explosions in young clusters. In the Upper Scorpius region we find that a supernova shell has interacted with dense clouds and that the peculiar stars lie close to or along the edges of interaction. We argue that the stars at or near the cloud faces are capable of acquiring this enriched material which is sufficiently slowed down. The magnetic accretion process of Havnes and Conti provides the mechanism of acquisition. This process with the associated magnetic braking accounts for the build-up in abundance anomalies and the slowing down of rotation with age.     

Spatial patterns of crime among Indian cities

An analysis of inter-city patterns of crime in India was undertaken. Using data for fourteen different types of crime and for 99 cities, standard correlation techniques were used to analyze the inter-relationships between different types of crime and the spatial distribution of these types. Factor analysis was applied to regionalize crime groups. An attempt is made to explain the crime patterns which emerge from the analysis, and the concentration of crime in the north-central region of India.     

On the impacts of ENSO and Indian Ocean dipole events on sub-regional Indian summer monsoon rainfall

The relative impacts of the ENSO and Indian Ocean dipole (IOD) events on Indian summer (June–September) monsoon rainfall at sub-regional scales have been examined in this study. GISST datasets from 1958 to 1998, along with Willmott and Matsuura gridded rainfall data, all India summer monsoon rainfall data, and homogeneous and sub-regional Indian rainfall datasets were used. The spatial distribution of partial correlations between the IOD and summer rainfall over India indicates a significant impact on rainfall along the monsoon trough regions, parts of the southwest coastal regions of India, and also over Pakistan, Afghanistan, and Iran. ENSO events have a wider impact, although opposite in nature over the monsoon trough region to that of IOD events. The ENSO (IOD) index is negatively (positively) correlated (significant at the 95% confidence level from a two-tailed Student t-test) with summer monsoon rainfall over seven (four) of the eight homogeneous rainfall zones of India. During summer, ENSO events also cause drought over northern Sri Lanka, whereas the IOD events cause surplus rainfall in its south. On monthly scales, the ENSO and IOD events have significant impacts on many parts of India. In general, the magnitude of ENSO-related correlations is greater than those related to the IOD. The monthly-stratified IOD variability during each of the months from July to September has a significant impact on Indian summer monsoon rainfall variability over different parts of India, confirming that strong IOD events indeed affect the Indian summer monsoon.

Sensitivity Analysis of Coal Rib Stability for Internal Mine Dump in Opencast Mine by Finite Element Modelling

The present paper discusses the impact of the geometrical parameters of the coal rib and the mine dump on the stability of the coal rib. The geometrical parameters such as the slope angle, the height of dragline dump, the height of main dump, the gradient of seam and the thickness of coal rib have been considered as input to the numerical model for the stability analysis of the coal rib. Sensitivity analysis has been performed based on the results of the analysis in term of factor of safety of the coal rib. The input parameters have been classified in terms of significance (i.e. very high significance, high significance medium significance and low significance). The factor of safety is more influenced by highly significant parameters. The height and the slope angle of dragline dump and the thickness of the coal rib are highly significant parameters for the stability of the coal rib. The gradient of the seam is a medium significant parameter whereas, height of main dump and the number of dragline cut dump are low significant parameters for stability of coal rib.