Comparative Analysis between DEM from Topographic, Aster GDEM and SRTM DEM

The difference between the DEM generated from Topographical map, ASTER DEM 1.5 arc second and SRTM DEM 3 arc second has been determine. As the ASTER GDEM has been known to be the highest resolution global digital elevation model purported to be 30m spacing (1 or 1.5) arc second, we have compared three different DEM’s by digitizing the contour of the existing topographical map covering the research area and downloading the ASTER GDEM data and SRTM data from online source. 3-D coordinates of some scattered was selected and generated from the three DEM created. Contour was also generated from the all the DEMs for further comparison. However, the contour value on the existing topographical map was converted from feet to meter to correspond with the ASTER GDEM and the SRTM DEM unit. The result of this research work was based on the Models generated from the 3D data obtained from the topographical DEM, ASTER GDEM and the SRTM DEM, Geographic information system GIS software like Global Mapper 13, Surfer 10 and ArcGIS 10.0 software was also used in doing the analysis. The height obtained from the topographic map was orthometric Height while the ASTER GDEM/SRTM DEM is an ellipsoidal height. In this study, the difference between the DEM generated from Topographical map, ASTER DEM 1.5 arc second and SRTM DEM 3 arc second has been determine. As the ASTER GDEM has been known to be the highest resolution global digital elevation model purported to be 30 m spacing i.e. 1 or 1.5 arc second, we have compare the three different DEM’s by digitizing the contour of the existing topographical map covering the research area as well downloaded the ASTER GDEM data and SRTM data from online source. 3-D coordinates of the some scattered was selected and generated from the three DEM created. Contour was also generated from the all the DEMs for further comparison. However, the contour value on the existing topographical map was converted from feet to meter to correspond with the ASTER GDEM and the SRTM DEM unit. The result of this research work was based on the Models generated from the 3D data obtained from the topographical DEM, ASTER GDEM and the SRTM DEM, Geographic information system GIS software like Global Mapper 13, Surfer 10 and ArcGIS 10.0 software was also used in doing the analysis. It is and evidence that the height obtained from the topographic map was orthometricHeight (Benchmark Elevations), and the ASTER GDEM/SRTM DEM is an ellipsoidal height (Geodetic Height)

Mode of action of plant-derived natural insecticides

Most of the chemical insecticides are neurotoxic, acting on targets in the central nervous system such as the membrane ion channels (DDT, pyrethroids), the enzyme acetylcholinesterase (organophosphate, carbamate), and the receptors of neurotransmitters (avermectins, neonicotinoids). The recently introduced diamide group of insecticides target the novel ryanodine receptor in the nervous system. Since pests continue to evolve resistance to compounds currently in use, new compounds with new modes of action are needed. Natural products could be a promising source for novel pest control agents. The origin of many of the important insecticide classes is traceable to a natural source as in the case of pyrethroids, avermectins, spinosads, and neonicotinoids. Although insect control agents acting on targets other than the nervous system such as insect growth regulators (e.g., azadirachtin, JH analogues, ecdysone antagonists) have been developed, due to their lack of contact toxicity, they are not quite successful, but find a place in the integrated pest management. Recent progress in understanding the biology of insect olfaction and taste offers new strategies for developing selective pest control agents. Decalesides, recently discovered natural insecticides, represent a new class of plant-derived insecticides targeting the tarsal gustatory receptors. In this chapter, we focus on the toxicity and mode of action of natural insecticides