Volume 11, Issue 2, 2011 April-June

Volume 11, No 2 Pages:
2011 April-June Articles: 7

A pinch of science for all seasons

There are people who openly suspect me, at least in an affable fashion, of having an undue obsession for evolution. But I do not claim, nay pretend, to possess an ounce of intelligible knowledge on the subject. Far from it. Being fanatical of anything is, I learn, the greatest stumbling block to the development of science. As the inimitable Carl Sagan once remarked, we should keep our mind open, but not too wide that our brains fall off.

Bacillus sphaericus in the biological control of mosquito vector complex

Vector control is primordial and very essential means for controlling transmission of filariasis, malaria, Japanese encephalitis and dengue in human society. Over the last few decades, there is growing realization that alternate methods to synthetic chemical control needs to be studied and perfected. Several control strategies have been adopted to control diseases transmitted by mosquitoes. Mosquito control programs worldwide have been evaluating the feasibility to implement biological control strategies by using Bacillus sphaericus (Bs). A comprehensive review cum research data is presented here to assess the potentiality of Bs in mosquito control operation. The major advantages of Bs are reduced application cost, safety to environment, human beings, animals and other non-target organisms. This paper explores the importance of Bs bacterial toxin in controlling vector mosquitoes.

Assessment of the water quality of Tlawng river in Aizawl, Mizoram

The present study was conducted with an aim to assess water quality of Tlawng river, a major source of potable water in Aizawl district of Mizoram, for a period of two years, i.e. from February 2007 to January 2009. The data analysed were compared with WHO (2004) and BIS-10500 standards. The average DO content ranged from 5.83 to 6.83 mgL-1 where the lowest DO level shows below permissible limit; BOD from 0.48 to 0.84 mgL-1 which indicates a low organic content in the water; total hardness from 48.75 to 102.71 mgL-1 CaCO3; calcium hardness from 29.14 to 56.14 mgL-1 CaCO3; magnesium hardness from 19.66 to 46.57 mgL-1 CaCO3 and fluoride content from 0.38 to 1.08 mgL-1 where some of the water samples shows below permissible limit. The DO content was negatively correlated with other parameters studied.

Petrochemical studies of metapelites of the area around Sonapahar, Meghalaya, India

Metapelites form a dominant component of the Precambrian basement complex in the Sonapahar area of Shillong Plateau, north-east India. In this paper, a new data on the major, minor and trace element compositions of these metapelites, an important member of the Precambrian basement rocks found in the Shillong plateau is reported. Petro-chemical data on these rocks were used to reproduce the nature and composition of their protolith. The mineral assemblages and petrographical observations indicated that metapelites of the study area were metamorphosed up to amphibolite to granulite facies metamorphism. Chemically, metapelites are characterized by relatively high Al2O3 (11.35-19.91 wt%), enrichments in MgO, FeO, MnO and TiO2; depletions in Na2O and especially CaO; low concentrations of Sc, Cr, Co, Ni, and Sr; high concentrations of Y, Nb, Zr, Hf, Ta, Th, U, and REE (rare earth elements) with prominent negative Eu-anomalies. Results indicated that these rocks were redeposited and metamorphosed products of Precambrian weathering crusts. The protolith of the metapelites was produced by erosion products of acid rocks, which were which are emplaced in volcanic arc environment.

Insect natural enemy complex in some agroforestry systems of Mizoram, India

Small scale agroforestry systems in north-east India are unique in terms of the complex biodiversity of both the agricultural produce and the adjoining biotic components, and thus, are excellent models for sustainable production system. The structure and biotic composition of the systems offer inbuilt sustainability and potential for reduced dependence on chemical fertilizers and pesticides. Maintenance and potential role of natural enemy complex in various compartments of such systems are discussed in the light of land use practices and holding size.

A simple study of surface effect in photoassisted field emission by using the Transfer Hamiltonian scheme: application to tungsten

We present here a model calculation of photoassisted field emission current (PFEC) from tungsten. Transfer Hamiltonian method was used for calculating the transition probability. Matrix element for the transition probability was calculated by using the wavefunctions which are deduced by applying the Kronig-Penney potential model.

Measurements of the equilibrium factor of radon in Aizawl, Mizoram, India

Radon (222Rn), being a radioactive gas has its parent nucleus originated from 238U. From 238U there is a series of 14 decays to form a stable nucleus of 206Pb. The equilibrium factor in its simple term may be defined as ratio of the amount of progeny nucleus to that of a parent nucleus. Measurement of Equilibrium Factor (F-factor) for radon has been carried out in 24 dwellings in Aizawl City, which were specifically selected according to the site location and materials used for construction of the dwellings. In measuring F-factor for radon we have made use of absorber-mounted nuclear track detectors (LR-115) which selectively register the tracks due to alpha emissions from 214Po which is the 222Rn progeny species. This detector is termed as DRPS (direct radon progeny sensor). DRPS is used for estimating the Equilibrium Equivalent Radon Concentration (EERC). The concentration of 222Rn is measured by using Solid State Nuclear Track Detector (LR-115) mounted in a BARC type twin cup dosimeter. The F-factor for radon is then calculated using the measured EERC and measured concentrations of radon. Our measurement shows the F-factor for radon in Aizawl city is 0.3, which is close to the worldwide value (0.4) for indoor conditions.

Brief Communication: A corrigendum to ‘Love wave at a layer medium bounded by irregular boundary surfaces

In the research article “Love wave at a layer medium bounded by irregular boundary surfaces” in Journal of Vibration and Control, Vol. 17(5), 789-795, five figures, from Figure 2 to 6, need to be corrected, as follows: