Studies on vibration of some rib-stiffened cantilever plates

The vibrational mode shapes and frequencies of rib-stiffened skew cantilever plates as determined by holographic interferometry are given. The effects of varying the sweep back angle, rib stiffness and aspect ratio are studied along with the influence of varying the boundary conditions at the root chord on the vibrational behavior of the plates. The study is applicable to investigating the vibrational behavior of stiffened plates often used in the design of guided rockets and missiles

Abrupt transitions in turbulent thermoacoustic systems

Abrupt transitions to the state of thermoacoustic instability (TAI) in gas turbine combustors are a significant challenge plaguing the development of next-generation low-emission aircraft and power generation engines. In this paper, we present the observation of abrupt transition in three disparate turbulent thermoacoustic systems: an annular combustor, a swirl-stabilized combustor, and a preheated bluff-body stabilized combustor. Using a low-order stochastic thermoacoustic model, we show that the reported abrupt transitions occur when an initially stable, supercritical limit cycle becomes unstable, leading to a secondary bifurcation to a large amplitude limit cycle solution. The states of combustion noise and intermittency observed in these turbulent combustors are well captured by the additive stochastic noise in the model. Through amplitude reduction, we analyze the underlying potential functions affecting the stability of the observed dynamical states. Finally, we make use of the Fokker-Planck equation, educing the effect of stochastic fluctuations on subcritical and secondary bifurcation. We conclude that a high enough intensity of stochastic fluctuations which transforms a subcritical bifurcation into an intermittency-facilitated continuous transition may have little effect on the abrupt nature of secondary bifurcation. Our findings imply the high likelihood of abrupt transitions in turbulent combustors possessing higher-order nonlinearities where turbulence intensities are disproportionate to the large amplitude limit cycle solution

Effect of nurse culture on inducing division of isolated pollen protoplasts of Hevea brasiliensis

Haploids are of great relevance in crop improvement of Hevea, a highly heterozygous tree species with a long breeding cycle. The isolation and culture of pollen protoplasts may be a viable proposition for raising haploid plants/ homozygous lines in Hevea. The present work envisages the development of a method for the isolation and culture of pollen protoplasts of Hevea. Effect of different nurse cultures on the development of cultured protoplasts has been studied. Intact pollen grains were isolated from mature male flowers of Hevea prior to opening. Viable protoplasts in high yield could be isolated from these pollen grains when exposed to a mixture of 0.5 per cent cellulase and 0.05 per cent pectolyase in the presence of the osmotic stabilizers 0.6 M mannitol and 0.3 M sorbitol. These protoplasts were partially purified and cultured in the nutrient medium with three different nurse cultures namely embryogenic calli from Hevea, tobacco and carrot. Division of the cultured protoplasts leading to the formation of a few micro-colonies was observed in the medium containing 0.8 mg l-1 2, 4-D and 0.5 mg l-1 BA and enriched with Hevea nurse culture. Cultures with micro-colonies are dark incubated for further development. This is the first report of division of pollen protoplasts and micro-colony formation in Hevea brasiliensis

Studies of planktonic Ostracoda collected from Arabian Sea and Bay of Bengal

General distribution and numerical abundance of planktonic ostracods, as a whole, in the Exclusive Economic Zone of India and nearby seas based on 1086 collections (1985-'88) are discussed. The average density of ostracods in the area investigated was estimated to be 17395/1000 m . The ostracods occurred far more abundantly in the shelf waters than in the oceanic areas. Samples collected indicated that 95% of the ostracod population occurred off the west coast of India round the year. They were found remarkably high (61168/1000 m\ 63.3%) between 10°N and 15°N off the west coast, while their abundance between 10°N and 15°N off the east coast of India was the lowest (624/1000 m , 0.65%). The abundance of ostracods was always associated with monsoon when the maximum of 31920/1000 m was obtained and this was mainly due to the swarming nature of these organisms. The minimum was observed during the premonsoon period when an average of 1508/1000 m ostracods occurred. Comparison of ostracod distribution in the EEZ of India between day and night yielded values of 30.95 and 69.05% respectively, which showed that they are more abundant during night, thereby illustrating pronounced diurnal vertical migration

Polymeric Systems for the Delivery of Herbicides to Improve Weed Control Efficiency

Weeds are unwanted plants, which interfere with the crop production. Weeds compete with crops for resources, causing severe yield loss. Chemical weed control through herbicides is a quite effective and reliable strategy to manage weeds. Herbicides constitute a major share of the global pesticide market. However, the applied herbicides undergo losses in the agroecosystem in different ways (chemical degradation, microbial decomposition, photo-degradation, leaching, run-off, and volatilization), thus lowering the herbicidal action coupled with contaminating ecosystem and groundwater. Encapsulation of herbicides is an innovative approach that addresses issues associated with the application of herbicides for controlling weeds. Encapsulation represents the embedding of an active ingredient in shell of polymeric material to achieve the controlled release of the active ingredient at the desired rate. The encapsulation of herbicides enhances stability, solubility, and bioactivity and alters the release pattern of herbicide resulting in improved weed control efficiency. Further, encapsulation lowers the application rate of herbicides, which in turn reduces the residue carryover of herbicide in soil and minimizes the environmental hazards. Therefore, encapsulated herbicide formulation has greater significance in the future weed management and will become ground-breaking technology in the chemical era of weed control

Distribution and abundance of cladocerans in the eastern Arabian Sea

Of the two species, Penilia avirostris Dana and Evadne tergestina Claus encountered, 86% of the population of the former occurred within the 50 m depth zone and 75% of the total population of the latter in the 50 m-100 m depth zone. Striking day-night variations in the population densities of Penilia and Evadne were observed. The samples collected at night contained 99.7% and 88% of the populations of the former and latter species respectively. Swarming of Evadne and Penilia is a regular phenomenon during the southwest monsoon season.The highest concentration of the former species was observed in August and that of the latter in September. High concentrations of Penilia and Evadne were observed in the 30 m depth zone off Cochin and in the 40 m depth zone off Karwar. The abundance of Penilia observed in the 30 m depth zone of Wadge Bank off Cape Comorin coincided with its maximum recorded in August off Cochin. The length frequency studies on Penilia and Evadne showed that different size classes dominated in the different regions from 07°N to 19°N and that an increase in size of the individuals was evident from south to north in both Penilia and Evadne. Fecundity of Penilia was the highest in the southernmost region between 07°00'N and 09°00'N while that of Evadne was in the northern region, 15°N- 19°N. Gamogenetic females of both Penilia and Evadne were very few in number. Occurrence of large numbers of parthenogenetic females of Penilia and Evadne with well developed advanced embroys in their brood pouches in the night samples probably suggest nocturnal brood maturation

Aplastic Crisis as Primary Manifestation of Systemic Lupus Erythematosus

Aplastic crisis is an unusual feature of systemic lupus erythematosus (SLE). We report the case of a 54-year-old woman presenting with both (extravascular) Coombs-positive hemolytic anemia and laboratory findings of bone marrow hyporegeneration with concomitant severe neutropenia. A bone marrow biopsy confirmed aplastic crisis. Diagnostic work-up revealed soaring titers of autoantibodies (anti-nuclear, anti-double-stranded DNA, anti-cardiolipin-IgM, and anti-beta 2-glykoprotein-IgM antibodies), indicating a connective tissue disease as the most plausible reason for bone marrow insufficiency. As the criteria for SLE were fulfilled, we initiated an immunosuppressive therapy by steroids, which led to a rapid complete hematologic and clinical remission in our patient. In this case, we could report on one of the rare cases of SLE-induced aplastic crisis showing that this condition can be entirely reversed by immunosuppressive treatment and that SLE-induced aplastic crisis yields a good prognosis. In conclusion, in a case of aplastic crisis, physicians should be aware that SLE can be a rare cause that is accessible to specific treatment