Mapping forest biomass in India through aerial photographs and nondestructive field sampling

A method for mapping of forest biomass using black-and-white aerial photographs and nondestructive field sampling is described through a case study of Ladhiya subcatchment in Kumaun Himalaya, India. Forest types were mapped using aerial photographs and field checks. Each forest type was divided into five crown cover classes. Mean crown cover for each class was determined in the field. Density and basal cover were measured on reference sites. Stand biomass was estimated by using biomass estimation equations, mean girth and mean density on the reference sites. Regression equations were developed between crown cover and basal cover, and between crown cover and stand biomass. Mean basal cover and mean stand biomass for each photo-interpreted crown cover class were estimated through these equations. Forest biomass values were substituted for crown cover classes on the interpreted map.     

'Clean' spectral analysis of long-term sea-level changes

A new ‘clean’ spectral technique has been applied, for the first time, to analyse a record of long-term sea-level fluctuation during the last 200 million year (Myr). The technique is based on a one dimensional complex deconvolution algorithm and removes the effects of the data sampling as well as the artifacts arising from the choice of data window. The analysis reveals a dominant periodicity of 33 Myr in the sea-level variations. This periodicity compares well with the known half-period of the Sun's oscillation perpendicular to the galactic plane. Interestingly, a 33 Myr periodicity can also be correlated with the reported mass extinction cycles and other geological periodicities. The results suggest galactic forcing as a possible driving mechanism for quasi-periodic terrestrial processes.     

Square Kilometre Array: The radio telescope of the XXI century

The Square Kilometre Array (SKA) will be the world’s largest and most sensitive radio telescope. It will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of theUniverse, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. This project envisages the construction of 133 15-m antennas in South Africa and 131072 log-periodic antennas in Australia, together with the associated infrastructure in the two desert sites. In addition, the SKA is an exemplar Big Data project, with data rates of over 10 Tbps being transported from the telescope to HPC/HTC facilities.     

Spherically-symmetric gravitational sources of purely electromagnetic origin

The present paper is a continuation of our earlier work on gravitational sources of purely electromagnetic origin, known in the literature as electromagnetic mass models. Here we have shown that a bounded (regular) interior static sperical-symmetric charged dust, if exists, can only be of electromagnetic origin.     

Magnetic polarity stratigraphy of the Bhuban succession,Surma Group,Tripura-Mizoram accretionary belt

A 1355 m thick Bhuban sequence exposed along Tuirial section in the Aizawl district, Mizoram has been studied for magnetostratigraphic and rock magnetic attributes. The study reveals mono-mineral nature of the rocks with magnetite in the range of Stable Single Domain (SSD) showing the most favourable mineralogy to produce authentic (Natural Remanent Magnetization) NRM directions. Using routine demagnetization methods we reveal a total of 7 normal magneto-zones in the studied part of the Tuirial section. Correlation of the observed polarity with GPTS gives ages ∼12.5 Ma to ∼8 Ma. A notable increase in the rate of sedimentation at ∼9.5 Ma (∼750 m level in the section) indicates facies change from turbidite like sequence to pro-delta system. Detailed sedimentologic work is under progress to relate the magnetostratigraphy to understand some of the basin evolutionary processes.     

Growing stock with aerial photographs

For assessment of growing stock, the role of aerial photographs mairly consists of volume class stratification, knowing proportion of various stratum and in providing layout for ground sample plots along with their precise location on the the ground. Plain Sal stratum was stratified into three volume classes on the basis of volume stereograms and standard deviation in each stratum estimated on the basis of reconnaissance data. 63 ground plots were needed for ± 5 cum (E = ± 5) accuracy for optimum allocation. Volume in 0.1 hectare circular plots was obtained from measurement of all trees above 10 cm dbh. The mean volume was 124 cum per hectare ± 9.55 cum at 95% probability level. A comparison with Working Plan figures revealed a close similarity. Advantage in time and cost for getting information on growing stock by the use of aerial photographs have been highlighted.     

Structural events and metamorphic consequences in Almora Nappe,during Himalayan collision tectonics

Almora Nappe in Uttarakhand, India, is a Lesser Himalayan representative of the Himalayan Metamorphic Belt that was tectonically transported over the Main Central Thrust (MCT) from Higher Himalaya. The Basal Shear zone of Almora Nappe shows complicated structural pattern of polyphase deformation and metamorphism. The rocks exposed along the northern and southern margins of this nappe are highly mylonitized while the degree of mylonitization decreases towards the central part where the rocks eventually grade into unmylonitized metamorphics.Mylonitized rocks near the roof of the Basal Shear zone show dynamic metamorphism (M₂) reaching upto greenschist facies (～450 °C/4 kbar). In the central part of nappe the unmylonitized schists and gneisses are affected by regional metamorphism (M₁) reaching upper amphibolite facies (～4.0–7.9 kbar and ～500–709 °C). Four zones of regional metamorphism progressing from chlorite–biotite to sillimanite–K-feldspar zone demarcated by specific reaction isograds have been identified. These metamorphic zones show a repetition suggesting that the zones are involved in tight F₂ – folding which has affected the metamorphics. South of the Almora town, the regionally metamorphosed rocks have been intruded by Almora Granite (560 ± 20 Ma) resulting in contact metamorphism. The contact metamorphic signatures overprint the regional S₂ foliation. It is inferred that the dominant regional metamorphism in Almora Nappe is highly likely to be of pre-Himalayan (Precambrian!) age.     

Spectral delineation of albite zone using ASTER data in Khetri Copper Belt

The Khetri Copper Belt is well known because of its economically viable Cu deposits. In this region, there is a linear narrow zone following a major crustal fracture. Along this zone, due to hydrothermal activity and subsequent alteration, a new rock, albitite has formed. The study presents an account of the spectral analysis of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) dataset for albitite mapping in the Khetri Copper Belt. Spectral angle mapper algorithm is applied on the ASTER data taking the ground sample reflectance spectra (VNIR–SWIR) and image derived spectra (TIR) as reference spectra. The albitite-classified areas are analyzed spatially and statistically to determine the extent of albitite zone in the study area. This research is to contribute to the better understanding of the spatial extent of the albitite zone which will assist in determining the potential for the mineralization in the area. The remote sensing approach of utilizing multichannel data offers the capability to resolve the key geological features of this geologically dynamic area.     

Effects of density, temperature and velocity gradients on inertial Alfven wave in cusp region

The kinetic approach is used to evaluate the dispersion relation and growth/damping rate of inertial Alfven wave (IAW) with density, temperature and velocity gradients in an inhomogeneous plasma. The effects of gradient terms are studied for both the regions k_⊥ρ_i<1 and k_⊥ρ_i>1, where k_⊥ is the perpendicular wave number and ρ_i is the ion gyroradius. The relevance of theoretical results so obtained is predicted in accordance to the FAST observations in the cusp region. The results are interpreted for the space plasma parameters appropriate to the cusp region. This study elucidates a possible scenario to account for the particle acceleration and the wave dissipation in inhomogeneous plasmas. This model is also able to explain many features observed in plasma sheet boundary layer as well as to evaluate the dispersion relation, growth/damping rate and growth/damping length of inertial Alfven wave. It is found that density, temperature and velocity gradients control the wave frequency and effectively enhance the growth rate of inertial Alfven wave.     

Inhomogeneous Plane Symmetric Models in a Scalar-Tensor Theory

For the general plane symmetric metric, some exact solutions of Einstein field equations in the scalar tensor theory developed by Saez and Ballestev are presented in vaccum and in the presence of stiff fluid. The physical and kinematical features of the models are also discussed. This revised version was published online in July 2006 with corrections to the Cover Date.