Nature watch

Marine turtles are known to migrate several thousands of kilometres between their feeding and breeding grounds. These migrations have been studied by the application of metal tags on flippers, with intense monitoring at nesting sites, and opportunistic recovery in offshore waters, providing information on turtle movements. Often, several thousands of tags have been applied with very low levels of recapture. Satellite telemetry is a high-tech, and expensive, method to track turtles during their migration across the open ocean. Molecular genetic techniques have offered ways to track turtles both through space and time. The comparison of genetic haplotypes from different regions makes it possible to study population structure, test theories of natal homing, and even assign feeding populations to nesting sites and vice versa. The study of these haplotypes has also made it possible to look at relationships between species and populations, and study evolutionary biogeography or phylogeography of these animals.     

Nature watch

Ridleys are unique amongst sea turtles in exhibiting massnesting, when several thousand turtles migrate en masse to their nesting ground to mate and nest simultaneously. Gahirmatha, in Orissa, has the largest sea turtle rookery in the world, with 100,000 to 500,000 turtles nesting there in most years. Mass mortality and fragmentation of the beach led to the failure of the arribada in 1997 and 1998, but more than 200,000 turtles nested on the 2 km long island in Gahirmatha in March, 1999. Despite the occurrence of the arribada, the outlook for the turtles is.bleak since 10000 turtles were drowned as incidental catch in shrimp trawling operations. Over 40,000 turtles have been washed ashore dead since 1994 as a result of drowning in trawl fishing nets. The implementation of existing laws preventing mechanised fishing in near-shore waters and the mandatory use of turtle excluder devices on trawlers would substantially reduce mortality. The consolidation of current conservation efforts is necessary to ensure that this species does not disappear from Indian waters in the near future     

Advertising Practitioner Perceptions of HDTV Advertising: A Diffusion of Innovations Perspective

Abstract

A nationwide online survey of advertising agency executives was conducted to investigate attitudes toward high-definition television (HDTV) diffusion. The survey was completed by 70 practitioners. The majority of respondents (85.9%) had viewed HDTV, but only 18.6% owned an HDTV set. Among non-owners of HDTV sets, 50% said they would not be acquiring 1 for at least 24 months. More than one half of the respondents believed that HDTV would not become the norm for 5 or more years. Respondents recognized the benefits of HDTV, but were not yet comfortable recommending HD advertising to clients. Factors inhibiting greater support of HDTV advertising include perceptions of insufficient HDTV programming, low HDTV diffusion among viewers, and greater cost of producing HD ads. Agency executives feel under-informed about HDTV, and would like to learn more about it. Industry groups interested in promoting greater acceptance of HDTV among advertising practitioners need to educate executives about the actual rate of HDTV diffusion to convince them that the medium is capable of attaining critical mass.     

Nature watch

Sea turtles are a fascinating group of marine reptiles that evolved millions of years ago. They show an intriguing variety of strategies to deal with their aquatic mode of life. Their migrations are legendary, and the mass nesting of the Ridleys is one of nature's most extraordinary spectacles. The eight species are all endangered due to human activities. While some have been exploited for meat, others have suffered due to factors such as pollution. This article details some of the more interesting aspects of their life history and examines their decline in recent times.     

Nature watch

The Montane Ecosystem, its decline through numerous human acitivities and its relevance to the development of conservation strategies are described in this article.     

Nature watch

Shield tails are a group of snakes belonging to the family Uropeltidae, endemic to the Western Ghats and Sri Lanka. They are small, beautiful non-poisonous snakes with bright colours, found at high altitudes in the ‘shola’ forests. They spend much of their life burrowing 1–2 metres beneath the surface, in search of their favourite food, earthworms. Loss of habitat has been a major cause for their decline and many of the species may now be endangered.     

Regulation of DNA conformations and dynamics in flows with hybrid field microfluidics

Visualizing single DNA dynamics in flow provides a wealth of physical insights in biophysics and complex flow study. However, large signal fluctuations, generated from diversified conformations, deformation history dependent dynamics and flow induced stochastic tumbling, often frustrate its wide adoption in single molecule and polymer flow study. We use a hybrid field microfluidic (HFM) approach, in which an electric field is imposed at desired locations and appropriate moments to balance the flow stress on charged molecules, to effectively regulate the initial conformations and the deformation dynamics of macromolecules in flow. With λ-DNA and a steady laminar shear flow as the model system, we herein studied the performance of HFM on regulating DNA trapping, relaxation, coil-stretch transition, and accumulation. DNA molecules were found to get captured in the focused planes when motions caused by flow, and the electric field were balanced. The trapped macromolecules relaxed in two different routes while eventually became more uniform in size and globule conformations. When removing the electric field, the sudden stretching dynamics of DNA molecules exhibited a more pronounced extension overshoot in their transient response under a true step function of flow stress while similar behaviors to what other pioneering work in steady shear flow. Such regulation strategies could be useful to control the conformations of other important macromolecules (e.g., proteins) and help better reveal their molecular dynamics.