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Accurate information about the built-up area in a city or town is essential for urban planners for proper planning of urban infrastructure facilities and other basic amenities. The normalized difference indices available in literature for built-up area extraction are mostly based on moderate resolution images such as Landsat Thematic Mapper (TM) and enhanced TM (ETM+) and may not be applicable for high resolution images such as Sentinel-2A. In the present study, an attempt has been made to extract the built-up area from Sentinel-2A satellite data of Chennai, India using normalized difference index (NDI) with different band combinations. It was found that the built-up area was clearly distinguishable when the index value ranges between -0.29 and -0.09 in blue and nearinfrared (NIR) band combination. Post extraction editing using Google satellite imagery was also attempted to improve the extraction results. The results showed an overall accuracy of 90% and Kappa value of 0.785. Same approach when applied for another area also yields good results with overall accuracy of 92% and Kappa value of 0.83. As the proposed approach is simple to understand, yields accurate results and requires only open source data, the same can be used for extracting the built-up area using Sentinel-2A and Google satellite imagery. [ABSTRACT FROM AUTHOR]

The mortality pattern in Murrah and Surti buffalo calves was studied for a period of 11 years (1991-2001) from the available records in certain organized farms of Tamil Nadu for four seasons viz. hot, south west monsoon, northeast monsoon and cold seasons. Data pertaining to 471 death records of buffalo calves were collected and analyzed. High (P<0.05) percentage of mortality occurred in male (18.58 ± 0.82, 20.20 ± 0.58) than the female (14.31 ± 0.53, 19.65 ± 0.59) calves in both Murrah and Surti graded respectively. The Surti graded showed heavier (P<0.01) losses than the Murrah calves. High (P<0.01) calf losses during cold season (11.37 ± 2.01), followed by northeast monsoon (9.50 ± 1.11) for Murrah and cold (14.27 ± 1.66) and northeast monsoon (9.80 ± 1.20) for Surti graded buffalo were noticed. The incidence of pneumonia and enteritis was 39.19 and 24.91 in cold season, 32.17 and 16.79 per cent in hot, 30.67 and 25.33 per cent in northeast monsoon, 27.17 and 21.00 per cent in southwest monsoon which caused maximum mortality in buffalo calves. [ABSTRACT FROM AUTHOR]