Natural fruit set in Vanilla wightiana Lindl., an endangered species from Andhra Pradesh, India

Vanilla wightiana Lindt, described as an extremely endangered wild species, occurs in the Eastern Ghat forest ranges of East Godavari District of Andhra Pradesh, India. &nbsp

BOBMEX: the Bay of Bengal monsoon experiment

The first observational experiment under the Indian Climate Research Programme, called the Bay of Bengal Monsoon Experiment (BOBMEX), was carried out during July-August 1999. BOBMEX was aimed at measurements of important variables of the atmosphere, ocean, and their interface to gain deeper insight into some of the processes that govern the variability of organized convection over the bay. Simultaneous time series observations were carried out in the northern and southern Bay of Bengal from ships and moored buoys. About 80 scientists from 15 different institutions in India collaborated during BOBMEX to make observations in most-hostile conditions of the raging monsoon. In this paper, the objectives and the design of BOBMEX are described and some initial results presented. During the BOBMEX field phase there were several active spells of convection over the bay, separated by weak spells. Observation with high-resolution radiosondes, launched for the first time over the northern bay, showed that the magnitudes of the convective available potential energy (CAPE) and the convective inhibition energy were comparable to those for the atmosphere over the west Pacific warm pool. CAPE decreased by 2-3 kJ kg-1 following convection, and recovered in a time period of 1-2 days. The surface wind speed was generally higher than 8 m s-1. The thermohaline structure as well as its time evolution during the BOBMEX field phase were found to be different in the northern bay than in the southern bay. Over both the regions, the SST decreased during rain events and increased in cloud-free conditions. Over the season as a whole, the upper-layer salinity decreased for the north bay and increased for the south bay. The variation in SST during 1999 was found to be of smaller amplitude than in 1998. Further analysis of the surface fluxes and currents is expected to give insight into the nature of coupling

Composition Dependent Study of AC conductivity in AsSe samples

The room temperature AC conductivity σ(ω) of amorphous AsSe samples with various compositions have been measured in the 103 -106 Hz frequency range. The results indicate that ac conductivity is proportional to n with n=0.89±.01 in the 103 –106 Hz frequency range. Consideration of different models for the frequency –dependent conductivity leads to thermally activated hopping as the most likely processCochin University of Science and TechnologyInternational Journal of Scientific and Research Publications, Volume 4, Issue 5, May 201

Photoacoustic investigation of the optical and thermal properties of selected amorphous chalcogenide semiconductors

This thesis work has mainly concentrated on the investigation of the ,optical and thermal properties of binary semiconducting chalcogenide glasses belonging to the AivB¥5x and AZBXEX families. The technique used for these studies is a relatively new one namely, the photoacoustic (PA) technique. This technique is based on the detection of acoustic signal produced in an enclosed volume when the sample is irradiated by an intensity modulated radiation. The signal produced depends upon the optical properties of the sample, and the thermal properties of the sample, backing material and the surrounding gas. For the present studies an efficient signal beam gas-microphone PA spectrometer, consisting of a high power Xenon lamp, monochromator, light beam chopper, PA cell with microphone and lock-in amplifier, has been set up. Two PA cells have been fabricated: one for room temperature measurements and another for measurements at high temperatures. With the high temperature PA cell measurements can be taken upto 250°C. Provisions are incorporated. in both the cells to change the volume and to use different backing materials for the sample. The cells have been calibrated by measuring the frequency response of the cells using carbon black as the sampleCochin University of Science And TechnologyDepartment of physics, Cochin University of Science And Technolog

Contribution to the bryophyte flora of India: the Aralam Wildlife Sanctuary in the Western Ghats

The bryophyte flora of the Aralam Wildlife Sanctuary in the Western Ghats of India is catalogued for the first time. The catalogue consists of 116 taxa (89 mosses, 27 liverworts), of which two are new for India (Plagiochila singularis, Vesicularia dubyana), 21 species are newly reported for Peninsular India (Clastobryopsis planula var. delicata, Barbella chrysonema, Brachymenium leptophyllum, Brachythecium rutabulum, Cololejeunea longifolia, Cyathodium tuberosum, Dicranella amplexans, Didymodon vinealis, Duthiella wallichi, Fabronia assamica, Haplocladium microphyllum, Himantocladium cyclophyllum, Homalia trichomanoides var. trichomanoides, Isopterygium serrulatum, Leskea perstricta, Lopholejeunea kashyapii, Leptotrichella assamica, Macromitrium turgidum, Rhynchostegium hookeri, Splachnobryum assamicum, Thamnobryum siamense) and another 14 species are new for Kerala State (Atrichum pallidum, Chionostomum rostratum, Claopodium prionophyllum, Cololejeunea lanciloba, Cyathophorum adiantum, Dicranella divaricata, Entodontopsis wightii, Fissidens pellucidus, Glossadelphus glossoides, Isopterygium lignicola, Leucodon secundus, Neckeropsis exserta, Plagiochila bischleriana, Timmiella anomala). The species Jungermannia obliquifolia has also been reported as a taxon new to India (Nair et al. in press (a) from this area

Thermal diffusivity of IV-V-VI glassess - an evidence for the existence of a mechanical threshold

The thermal diffusivity of two sets of GexSbySe100-x-y, GexAsyTe100-x-y and SixAsyTe100-x-y glasses have been measured using the photoacoustic technique. The thermal diffusivity data of the three glass systems show maxima at the compositions corresponding to the average coordination number <r> = 2.60. These results have been interpreted in the light of the existence of a mechanical threshold and the formation and development of a layered structure in these network glasses

Thermal Changes of Impurity Core - Valence Luminescence in K1−xCsxClK_{1-x}Cs_{x}Cl and Rb1−xCsxClRb_{1-x}Cs_{x}Cl Mixed Crystals

The composition dependence of optical energy gap (E<SUB>g</SUB>) and thermal diffusivity a in three sets of Ge-Se-Te glasses, namely, Ge<SUB>x</SUB>Se<SUB>80-x</SUB>Te<SUB>20</SUB> (5 = x = 40), Ge<SUB>x</SUB>Se<SUB>75-x</SUB>Te<SUB>25</SUB> (5 ≤ x ≤ 40), and Ge<SUB>x</SUB>Se<SUB>65-x</SUB>Te<SUB>25</SUB> (5 ≤ x ≤ 37.5), have been studied using photoacoustic technique. The variation of a with average coordination number &lt;r&gt; shows a change in the slope at &lt;r&gt; = 2.4 and 2.67. E<SUB>g</SUB> shows a local maximum at &lt;r&gt; = 2.67. The results are discussed on the basis of the topological and chemical threshold exhibited by covalent network glasses. The relative sensitivity of a and E<SUB>g</SUB> to these phenomena is discussed