Spin, charge and orbital ordering in La0.5Sr1.5MnO4

We have analyzed the experimental evidence of charge and orbital ordering in La0.5Sr1.5MnO4 using first principles band structure calculations. Our results suggest the presence of two types of Mn sites in the system. One of the Mn sites behaves like an Mn(3+) ion, favoring a Jahn-Teller distortion of the surrounding oxygen atoms, while the distortion around the other is not a simple breathing mode kind. Band structure effects are found to dominate the experimental spectrum for orbital and charge ordering, providing an alternate explanation for the experimentally observed results.Comment: 4 pages + 3 figures; To appear in Phys. Rev. Let

Elastic Cheerios effect: self-assembly of cylinders on a soft solid

A rigid cylinder placed on a soft gel deforms its surface. When multiple cylinders are placed on the surface, they interact with each other via the topography of the deformed gel which serves as an energy landscape; as they move, the landscape changes which in turn changes their interaction. We use a combination of experiments, simple scaling estimates and numerical simulations to study the self-assembly of cylinders in this elastic analog of the Cheerios effect for capillary interactions on a fluid interface. Our results show that the effective two body interaction can be well described by an exponential attraction potential as a result of which the dynamics also show an exponential behavior with respect to the separation distance. When many cylinders are placed on the gel, the cylinders cluster together if they are not too far apart; otherwise their motion gets elastically arrested

Electronic Structure of Sr_2FeMoO_6

We have analysed the unusual electronic structure of Sr_2FeMoO_6 combining ab-initio and model Hamiltonian approaches. Our results indicate that there are strong enhancements of the intraatomic exchange strength at the Mo site as well as the antiferromagnetic coupling strength between Fe and Mo sites. We discuss the possibility of a negative effective Coulomb correlation strength (U_{eff}) at the Mo site due to these renormalised interaction strengths.Comment: To appear in Phys. Rev. Let

On the occurrence of red-baits in the indigenous boat seine fishery off Madras*

The red-baits Dipterygonotus leucogrammicus Bleeker of the family Emmelichthyidae is one of the important live baits used in the pole and line tuna fishery in Lakshadweep during January to April. No reports are available on the abundant occurrence of these fishes either in the mechanised trawler or indigenous fishing units. The present report deals with an unusual landing of the red baits in the indigenous boat seine fishery at Kottivakkamkuppam landing centre near Madras. Length measurements of a sample taken indicated the length range of 55-86 mm in the landings with the predominance of 71-75 mm size group. Since no ready market was available for red-baits in fresh condition, the entire catch was put to sundrying on the beach

Peeling from a patterned thin elastic film

Inspired by the observation that many naturally occurring adhesives arise as textured thin films, we consider the displacement controlled peeling of a flexible plate from an incision-patterned thin adhesive elastic layer. We find that crack initiation from an incision on the film occurs at a load much higher than that required to propagate it on a smooth adhesive surface; multiple incisions thus cause the crack to propagate intermittently. Microscopically, this mode of crack initiation and propagation in geometrically confined thin adhesive films is related to the nucleation of cavitation bubbles behind the incision which must grow and coalesce before a viable crack propagates. Our theoretical analysis allows us to rationalize these experimental observations qualitatively and quantitatively and suggests a simple design criterion for increasing the interfacial fracture toughness of adhesive films.Comment: 8 pages, To appear in Proceedings of Royal Society London, Ser.

QoS Framework for a Multi-stack based Heterogeneous Wireless Sensor Network

Wireless sensor nodes consist of a collection of sensor nodes with constrained resources in terms of processing power and battery energy. Wireless sensors networks are used increasingly in many industrial and consumer applications. Sensors detect events and send via multi hop routing to the sink node for processing the event. The routing path is established through proactive or reactive routing protocols. To improve the performance of the Wireless Sensor Networks, multi stack architecture is addressed. But the multi stack architecture has many problems with respect to life time, routing loop and QOS. In this work we propose a solution to address all these three problems of life time, routing loop and QOS in case of multi stack architecture

Oyster culture- Status and prospects

Most scientific studies on oyster resources, biology and farming have been carried out in the twentieth century. New approaches to our understanding of the intricate pattern of the oyster behaviour in respect of feeding, reproduction, larval development and disease control have enabled scientists to plan and undertake highly successful oyster farming in recent years. This is not only the situation in advanced countries but has become a distinct possibility in India. Scientists of the Central Marine Fisheries Research Institute have achieved remarkable success by carrying out extensive investigations relating to the breeding and farming of the edible oyster during the past one decade. In addition to the evaluation of the potentialities of natural resources in several zones of Indian coastal waters, estuaries and backwaters, suitable technologies for oyster farming and hatchery production of oyster seed have been developed by the CMFRI. It would only be a matter of time before commercial farming of the edible oyster takes place in the country

Pearl and Chank Fisheries - A New Outlook in Survey and Fishing

The Gulf of Mannar and the Palk Bay Zones of the east coast of the Madras state, particularly the area from Rameshwaram to Manapad, are of very great fishing importance as far as the pearl and chank fisheries are concerned. The submarine plateau of the inshore areas of the sea here affords excellent habitat for the growth of the shell fish, Xnrcvs pyrum (Linn.) (the sacred chank) and Pivcunla jucaia (Gould) (the pearl oyster). Chank fishing and pearl fishing in this zone had been conducted from time immemorial under the control of the State. All along the stretch of the sea-bottom, extensive, flat rocky patches occur at a distance of 8-12 miles from the shore within 7-12 fathoms, separated from one another and surrounded by equally extensive patches of fine sandy areas at the same or slightly deeper zones. Whereas the chanks prefer fine and soft sandy areas called locally 'Poochi-manal' or 'pirals' as their abode, the oysters are sedentary and are attached to hard rocky substrata called'Pa ar'. Occasionally tfe one is found in the natural habitat of the other. There are more than 65 well known'Paars' (rocky sea-bottom) and lesser in number of good chank grounds in the Gulf of Mannar known to fisherman by their depth and location fixed by land bearings. The sea bottrm on Palk Bay side is not rocky, at the same time less shallow also. The chanks rrowing in this zone are classified as 'Patti' variety which is priced less than the 'Jadhi' variety fished from Rameshwaram to Tiruchendur. The differentiation between these two lie in the latter being elongate, elegantly formed, comparatively narrower and with well balanced spire whereas the former is with a short spire. The Tirunelveli and Ramanathapuram chanks now constitute the bulk to meet the demand from Bengal for chank bangle industry

Underwater ecological observations in the Gulf of Mannar, off Tuticorin-II. The Occurrence of the Synaptid Chondrocloea along with the Massive Sponge, Petrosia

In this paper an interesting instance of association between a sponge and a synaptid, which was observed during the course of our underwater dives with SCUBA is recorded. The rocky patches of the sea bottom off Tuticorin exhibited certain sharacteristic fauna depending on the depth and locality. For instance, the shorepvard rocky floor in the 10-13 metre range was characterized by, amongst other things, the small and medium sized sponges firmly attached to the substratum and Ivas conspicuous by the absence of the massive sponge of the genus Petrosla