COMPARATIVE STUDY OF ANTIMICROBIAL ACTIVITY ON FRESH AND DRIED Zingiber officinale Rosc

The present study to investigate the antimicrobial activity, from rhizome fresh and dried Zingiber officinale Rosc. In the present study to observe the antibacterial activity using the microorganisms such as E. coli, Staphylococcus aureus, K. pneumoniae and Pseudomonas aeroginosa were studied by using disc diffusion method. The maximum zone of inhibition were observed in K. pneumoniae (25 mm), followed by Staphylococcus aureus (24 mm), Pseudomonas aeroginosa and E. coli each showed 22 mm. The antifungal activity carried out by using the microorganisms Aspergillus flavus, A. terreus, Penicillum sp and Fusarium sp were studied by using agar well diffusion method. The maximum zone of inhibition were observed at the concentration of 100 µg of fresh sample against Fusarium sp (14 mm) followed by A. flavus (12 mm), A. terreus (10 mm) and Penicillum sp (10 mm). &nbsp

Time clustering of earthquakes in the Sumatra-Andaman and Himalayan regions

Increased frequency of earthquakes in the Sumatra–Andaman region in the past 10 years reflects time clustering of earthquakes and does not necessarily imply low recurrence interval of earthquake in the region. Time clustering of earthquakes can occur either due to the stress change (either through static or dynamic stress transfer) caused by the occurrence of a great earthquake in the region, or it could just be a chance in which earthquake occurrence is almost simultaneous in two or more segments, despite differences in the earthquake cycle due to difference in the phase of strain accumulation, rheology, plate convergence rate, etc. in these segments. We note that the Himalaya and the adjoining regions too showed earthquake time clustering during 1897–1950

Modulational Instability in Linearly Coupled Asymmetric Dual-Core Fibers

We investigate modulational instability (MI) in asymmetric dual-core nonlinear directional couplers incorporating the effects of the differences in effective mode areas and group velocity dispersions, as well as phase- and group-velocity mismatches. Using coupled-mode equations for this system, we identify MI conditions from the linearization with respect to small perturbations. First, we compare the MI spectra of the asymmetric system and its symmetric counterpart in the case of the anomalous group-velocity dispersion (GVD). In particular, it is demonstrated that the increase of the inter-core linear-coupling coefficient leads to a reduction of the MI gain spectrum in the asymmetric coupler. The analysis is extended for the asymmetric system in the normal-GVD regime, where the coupling induces and controls the MI, as well as for the system with opposite GVD signs in the two cores. Following the analytical consideration of the MI, numerical simulations are carried out to explore nonlinear development of the MI, revealing the generation of periodic chains of localized peaks with growing amplitudes, which may transform into arrays of solitons

Antarctica plate motion

We have analysed GPS measurements of site motion from fifty sites in the Antarctica, including the one set up by us at Maitri. The Maitri site exhibits a predominantly northward velocity of ~8 mm/year. Elsewhere on the Antarctica plate the site velocity estimates vary from 4 to 20 mm/year and exhibit spectacular rotation of the atlantic plate. The estimated pole of the Antarctica plate is located on the plate itself and thus the plate, surrounded by mostly the divergent plate margins, appear to spin along this pole. Large seasonal variations are seen in displacement time series from sites which are located closer to the pole

Slow rupture in Andaman during 2004 Sumatra-Andaman earthquake: a probable consequence of subduction of 90°E ridge

One of the most enigmatic features of the 2004 Sumatra–Andaman earthquake was the slow rupture speed and low slip on the northern part of the rupture under the Andaman region. We propose that the aseismic 90°E Ridge (NER) on the Indian Plate obliquely subducts under the Andaman frontal arc region. Though other possibilities also exist, we hypothesized that this ridge probably acted as a structural barrier influencing rupture characteristics of the earthquake. Here we present several features of the Andaman region that favour NER subduction under the region, which include (i) comparatively shallow bathymetry and trench depth, (ii) low seismicity, (iii) significant variation in the azimuths of coseismic horizontal offsets due to the 2004 Sumatra–Andaman earthquake, (iv) lack of post-seismic afterslip on the coseismic rupture in the Andaman frontal arc region, (v) low P wave with only small decrease in S wave speed from tomographic studies, (vi) gravity anomalies on the Indian Plate indicating continuation of the ridge under the Andaman frontal arc and (vii) lack of back arc volcanoes in the Andaman region