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1

Finite amplitude long wave instability of a film of conducting fluid flowing down an inclined plane in presence of electromagnetic field

100%

Dandapat B. S. , Mukhopadhyay A.

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2003

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tom Vol. 8, no 3

379-383

EN

Stability characteristics of a thin conducting liquid film flowing down, on a non-conducting plane in the presence of the electromagnetic field is investigated under the assumption of a small magnetic Reynolds number. A surface evolution equation is derived by using the long-wave approximation method. A linear and non-linear stability analysis of the evolution equation shows that the magnetic field stabilizes the flow whereas the electric field stabilizes or destabilizes the flow depending on its orientation with the flow. It is found that both the subcritical instability and supercritical stability are possible in a finite amplitude regime. Two critical Hartmann numbers Mc and Mc>(Mc) are observed for subcritical and supercritical zones respectively. The existence of a subcritical unstable zone may be ruled out when Mc>Mc which is independent of other parameters whereas supercritical and explosive zones are possible till Mc

2

Unsupervised Pixel Classification in Satellite Imagery: A Two-stage Fuzzy Clustering Approach

100%

Mukhopadhyay A. , Maulik U.

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tom Vol. 86, nr 4

411-428

EN

A popular approach for landcover classification in remotely sensed satellite images is clustering the pixels in the spectral domain into several fuzzy partitions. It has been observed that performance of the clustering algorithms deteriorate with more and more overlaps in the data sets. Motivated by this observation, in this article a two-stage fuzzy clustering algorithm is described that utilizes the concept of points having significant membership to multiple classes. The points situated in the overlapped regions of different clusters are first identified and excluded from consideration while clustering. Thereafter, these points are given class labels based on Support vector Machine classifier which is trained by the remaining points. The well known Fuzzy C-Means algorithm and some recently proposed genetic clustering schemes are utilized in the process. The effectiveness of the two-stage clustering technique has been demonstrated on IRS remote sensing satellite images of the cities of Bombay and Calcutta and compared with other well known clustering techniques. Also statistical significance test has been carried out to establish the statistical significance of the clustering results.

3

Dose- and time-dependent micronucleus induction in peripheral erythrocytes of catfish, Heteropneustes fossilis (Bloch) by zinc

80%

Talapatra S. N. , Banerjee P. , Mukhopadhyay A.

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tom 04

EN

As far as the detection of metal genotoxicity in fish is concerned, micronucleus (MN) test is considered an extremely suitable measure. In this study, frequencies of micronucleated erythrocytes were scored in peripheral blood of catfish, Heteropneustes fossilis (bloch) after acute in-vivo exposure of zinc at different concentrations (5, 10 and 30 ppm) in the laboratory condition. These three concentrations of zinc were tested at different durations such as 24h, 48h, 72h and 96h respectively. Highly significant (P < 0.001) increased values were obtained for MN frequencies in the peripheral erythrocytes of exposed fishes compared to control groups of fishes. These results confirm that dose- and time-dependent micronucleation in the peripheral erythrocytes of fish after short-term exposure to zinc could provide valuable information regarding zinc containing effluent quality and also help in genetic biomonitoring with this test model. In this context safe concentration of zinc vis-a-vis genotoxicity range could be evaluated for future studies.

4

Survey of indoor air pollution and health symptoms at residential buildings

71%

Sarkar S. , Nandy A. , Talapatra S. N. , Basu R. , Mukhopadhyay A.

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nr 1

EN

This survey work summarizes the generation of indoor air pollutants (IAPs) through household products and activities and also the probable health symptoms of IAPs were discussed through questionnaire in the residential buildings of urban and semi urban area when compared to rural (control) area by door to door survey. The IAPs are categorized as physical, chemical and biological and surveyed as per the product(s) usage in the closed room of buildings. The survey results of IAPs generated from household products and activities, these are asbestos, fine particulate matters and ash as physical pollutants. The chemical pollutants are carbon mono and di oxide gases, phthalates; DDT, chlordane, heptachlor, o-phenylphenol; PBDEs, Formaldehyde, Other Aldehydes, lead, benzene, chloroform, para-dichlorobenzene, methylene chloride, perchloroethylene, styrene, benzene, formaldehyde, terpenes, styrene, phthalate esters, toluene, Propellant, pesticides, PAH, NOx, acrylamide, VOCs, acetone, HCl gas and biological pollutants are bacteria, fungi, viruses, house dust mites, animal dander; cockroaches, microbial spore. In respect to established health impact data, the health symptoms were recorded after survey in two areas viz. urban and semi urban area. The health symptoms were recorded as eye, nose, and throat irritation; allergic reactions, respiratory irritation, aggravated asthma, influenza and other infectious diseases may be the generation of IAPs. The urban and semi urban area are compared with rural (control) area in which no symptoms were found as per discussion. In the present survey it was concluded that the generation of IAPs may from household products and activities in the urban and semi urban area due to less ventilation facilities when compared to rural (control) area. This is a preliminary observation, further researches are needed in relation to measurement of physical, chemical and biological indoor pollutants in closed room of residential buildings and also health hazards study of residents by haematological, biochemical, enzymological and genotoxicological parameters.

5

Assessment of morphological damages of leaves of selected plant species due to vehicular air pollution, Kolkata, India

71%

Nandy A. , Talapatra S. N. , Bhattacharjee P. , Chaudhuri P. , Mukhopadhyay A.

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tom 04

EN

The present study deals to know morphological damages of leaves of four selected plant species near roadside due to vehicular air pollution in Kolkata, India. The selected plant species are Ficus bengalensis, Ficus religiosa, Alstonia scholaris and Neolamarckia cadamba as these are very common as avenue trees. The study area was selected as per Low vehicular load (LVL) as control area, moderate vehicular load (MVL) area, high vehicular load (HVL) area and heavy vehicular load (HeVL) These three sampling stations were selected on the basis of moderate, high and heavy traffic density and continuous vehicular movement as per visualization. The control area was considered as time dependent vehicular movement due to less traffic density. The morphological damages with special reference to length (L), breadth (B) and L/B ratio and visible injuries in leaves. The visible injuries such as pigmentation, chlorosis, necrosis and burning of leaves of four selected species is documented. There was an increasing and decreasing tends in all four plant species at all three vehicular emission exposed sites (MVL, HVL and HeVL) compared to control site (LVL). In all experimental sites such as MVL, HVL and HeVL, the extra growth and reduction pattern significantly (P < 0.001, 0.01 or 0.05) observed when compared to control site (LVL) for L, B and L/B ratio. The visible injuries (in %) of leaves were also observed in increasing trends. This study is a preliminary assessment of tolerant species that already have been used in greenbelt development to protect air pollutants as well as biological monitoring to know exact load of automobile air pollution but further researches are needed in relation to biochemical and genetic damage study. It was observed that out of four selected species Ficus bengalensis, Alstonia scholaris and Neolamarckia cadamba are more tolerant species and Ficus religiosa is a less tolerant species because of these may have fighting abilities by waxy coatings, accumulation and degradation abilities to vehicular air pollution at all exposed area when compared to control area.

6

Dosage and temporal dependent arsenic-induced mortality in Ceriodaphnia dubia: An effective biomarker for arsenic pollution

61%

Talapatra S. N. , Bhattacharya S. , Guha G. , Dutta S. , Chattopadhyay D. , Mukhopadhyay A.

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tom 02

EN

Arsenic (As) is a metalloid that causes severe water pollution due to its extravagant toxicity. Ceriodaphnia dubia, a freshwater crustacean, was selected as a model system to evaluate the degree of time and dosage dependent acute toxicity caused by pentavalent As [As(V)]. C. dubia were collected from a natural pond and treated with different concentrations of As(V) for 24 hours and 48 hours. For both 24 hours and 48 hours treatment periods, the mortality rates were increased significantly ( P< 0.05) with increase in As(V) concentrations. Simultaneously, it was also observed that As(V) - induced mortality in C. dubia also depended on the time of exposure to the metalloid. We propose this model as a low-cost technique towards rapid screening of water quality in relation to As contamination.