Travelling interplanetary disturbances detected using interplanetary scintillation at 327 MHz

Based on the advance predictions of two flare-generated shock fronts, obtained from the Space Environment Centre (SEC, NOAA, Boulder), observations of interplanetary scintillation (IPS) were carried out with the Ooty Radio Telescope (ORT) on a grid of appropriately located sources during the period 31 October to 5 November, 1992. Solar wind velocities were derived by fitting model spectra to the observed spectra and two travelling interplanetary disturbances were detected. Both disturbances were traced back to an active region on the Sun which was located close to a large coronal hole. The roles of flares and coronal holes in producing such disturbances are examined and it is shown that in the present case both the coronal hole and the active region probably played key roles in generating the two IPS disturbances.Currently on a Humboldt Fellowship at the Radioastronomisches Institut, D-53173, Bonn.     

New timing parameters and positions for 16 southern radio pulsars

We report timing observations on 16 pulsars obtained using the Ooty Radio Telescope operating at 327 MHz. Using these observations, spanning over a year, we have obtained values of period derivatives for the first time and refined the estimates of the periods for all pulsars in this sample. We also report improved positions for all cases where the earlier position estimates had an uncertainty of a few arcmin.     

Embryology of Maldives clownfish, Amphiprion nigripes (Amphiprioninae)

This study investigated the embryonic development of Maldives clownfish Amphiprion nigripes under natural conditions (28 - 30℃) at a lagoon of Agatti Island, Lakshadweep, India. The newly deposited fish egg was capsule-shaped and orange-red, with a (0.73 ± 0.04) mm3 yolk containing 5 - 10 fat globules. The embryonic development of fertilized eggs was divided into 26 stages and the time elapsing for each stage was recorded. Results showed that the cleavage was rapid, with the first division observed 1 h 20 min after fertilization. Blastulation occurred 4 h later, followed by gastrulation 12 h after fertilization, with a yolk volume of (0.61 ± 0.06) mm3. The organogenesis process started 22 h after fertilization when the blastopores closed and notochord formation began. The embryonic stage was recorded 24 h later, with the appearance of forebrain, midbrain, hindbrain, melanophores on yolk-sac and 22 somites, and a decreased yolk volume of (0.54 ± 0.08) mm3. Other organs developed well 31 h after fertilization, whereas the heart started beating and blood circulation began 78 h later. Red pigmentation (erytrophores) appeared 96 h after fertilization, with a small yolk volume of (0.22 ± 0.02) mm3. Mouth developed well and eyes were noticeable 120 h later, with head, pectoral fin and tail frequently moving 144 h after fertilization. The embryo reached the pre-hatching stage 168 h later and started to hatch after 170 - 180 h incubation. This study first detailed the embryonic development and yolk absorption of A. nigripes under natural conditions.     

Prioritization of subwatersheds based on quantitative morphometric analysis in lower Bhavani basin,Tamil Nadu,India using DEM and GIS techniques

Watershed prioritization is one of the most important processes in natural resource management system especially in areas of sustainable watershed development and planning. Morphometric characteristics are the viable entity to understand the hydrological behavior of the subwatershed. For prioritization of subwatershed, morphometric analysis was utilized by using the linear, areal, and relief aspects of the drainage basin. In this context, remote sensing and GIS has been proved to be an efficient tool to identify the morphological features. The Survey of India (SOI) topographical maps, satellite data IRS-LISS III, and Cartosat DEM data were utilized to understand the drainage pattern and also for prioritization of subwatershed areas. The prioritization of subwatershed has been attempted using novel and quantitative approaches based on compound parameter ranking for soil erosion. Lower compound factors were chosen as the most feasible for soil erosion. Based on the observation, eight subwatersheds with a higher degree of the slope were severely prone to soil erosion and remaining 21 subwatersheds occur in low-lying areas that can be developed as sustainable watersheds. The identified subwatershed requires immediate soil remediation and water conservation measures for efficient watershed planning and management. The proposed study might be helpful for resource planners, government agencies, private sectors, and other stake holders to take up soil conservation measures and fixation of water-harvesting structures for better decision making.     

Fishery provisions of the ICNT: Part 2

In the second of two articles analysing the fishery provisions of the ICNT/Rev 2, the author concentrates on unresolved legal problems of the world's marine fisheries. Difficulties associated with MSY and OSY, TAC, surplus, coastal state control over the EEZ, high-seas fishing, anadromous species, land-locked and geographically disadvantaged states, and sedentary species are discussed, and an assessment is made of the ICNT's attempt to ensure a more equitable distribution of world fishery resources.