Correlation among QPO frequencies and Quiescence-state Duration in Black Hole Candidate GRS 1915+105

We discover a definite correlation between the frequency of the quasi-periodic oscillations (QPO) in quiescence states and the duration of the quiescence state of the transient X-ray source GRS 1915+105. We find that while the QPO frequency can be explained with the oscillation of shocks in accretion flows, the switching of burst to quiescence states (and vice versa) and their duration can be explained by assuming an outflow from the post-shock region. The duration of the quiescence state is inversely related to the QPO-frequency. We derive this relation. We also find the correlation between the observed low ($\sim 0.001-0.01$Hz) and the intermediate (1-10Hz) QPO frequencies. Our analytical solutions are verified by analyzing several days of public-domain data from RXTE.Comment: Latex, 13 pages with 3 figures; Accepted for Publication in Astrophysical Journal Letter

Glimpses of Tribal Botanical Knowledge of Tirunelveli Hills, Western Ghats, India

In the present paper, 46 plant species of angiosperms belonging to 19 genera of Euphorbiaceae that occur naturally in the Tirunelveli Hills of western Ghats, India, were chosen for study. It was found that the uses of Euphorbiaceous plants by the inhabitants of this region cover a number of broad categories including food, various kinds of poisons, medicines, sundry types of oils, waxes, rubbers, varnishes, compounds for paints and other industrial products

Functional and radiological analysis of posterior lumbar interbody fusion in spondylolisthesis

Background:Spondylolisthesis is present in 5% of the adult population with clinical evidence of low back pain. These patients are treated initially by conservative measures, failing of which surgical intervention is mandatory. Majority of patients with varying degree of slip and disability ultimately require surgical intervention. In this study we are trying to analyse the functional outcome following posterior lumbar interbody fusion in spondylolisthesis.Methods: Posterior lumbar interbody fusion using pedicle screw and rods with cage was performed on 25 patients. 6 months follow-up was completed in 25 patients who were then reviewed at regular intervals. Out of the 25 patients, 17(68%) were females and 8(32%) were males. The mean age of the patients was 40.64 years. Out of 25 patients, 14 patients had listhesis at L4 – L5 level and another 11 at L5 – S1 level. 21(84%) were Isthmic variant and 4 (16%) were Degenerative spondylolisthesis.Results:The mean follow up period in this study of 25 patients is 19 months. Out of 25 patients, there was mean improvement of 18.96 in the Oswestry scoring index. The Visual analogue scale score showed a mean improvement of 6.48. Radiologically, the percentage of slip was decreased by a mean of 8.40%. One patient had a cage extrusion with no neurological deficit.Conclusions:The pedicle screw with rod and cage system is easy to use and provides the anatomic restoration of the isthmus in isthmic spondylolisthesis or restoring the stability after laminectomy/discectomy in degenerative spondylolisthesis. From our study, we strongly believe that this technique is very useful in low grade degenerative and isthmic spondylolisthesis

Spectral Signature of Wind Generation From The Post-Shock Region in GRS1915+105 Accretion Disk

Accretion and outflows are common in systems which include black holes. Especially important is the case of the well known micro-quasar GRS1915+105 in our own galaxy, where super-luminal outflows are detected. We present a few observation which are suggestive of an outflow which is generated very close to the black hole, within a few tens of Schwarzschild radii. In the presence of mass loss (e.g., an outflowing wind), the electron density of matter within the centrifugal pressure supported region (which generates hard X-rays) goes down and it is easier to cool these electrons by soft photons coming from the Keplerian disk. If, on the other hand, the post-shock region gains mass from outside, the spectra would be harder. These properties of spectral `softening' of the low state and `hardening' of the high state have been detected in several days of RXTE data of GRS1915+105 which we present here.Comment: 10 latex pages with four figures (Submitted Astronomy and Astrophysics, May 2000

Mode Structure of Disruption Precursors in TFTR Enhanced Reversed Shear Discharges

The mode structure of the disruption precursors in the TFTR enhanced reversed shear parameters has been studied by using T(subscript e) fluctuation profiles and q profiles obtained from Electron Cyclotron Emission (ECE) and Motional Stark Effect (MSE) measurements. The observed profiles of the radial displacement associated with the MHD modes were consistent with the displacement profiles expected from the ideal MHD external kink mode. The observed mode frequencies differ from the plasma toroidal rotation frequency measured with CVI charge-exchange recombination light. The independence of the mode frequency from the plasma rotation frequency supports the ideal MHD hypothesis. Possible causes of the frequency difference are discussed