Vela, its X-ray nebula, and the polarization of pulsar radiation

The recent identification of the perpendicular mode of radio polarization as the primary one in the Vela pulsar by Lai et al. (2001) is interpreted in terms of the maser mechanism proposed by Luo & Melrose (1995). We suggest that such a mechanism may also be operative for the parallel mode which opens up the possibility of accounting for all types of polarization observed in pulsars. We propose an alternative interpretation of the arcs in the nebular X-radiation observed by Pavlov et al.(2000) & Helfand et al. (2001) with the Chandra Observatory, and interpreted by the latter as an equatorial wind. We interpret the arcs as traces of the particle beams from the two magnetic poles at the shock front. We also propose that the alignment with the rotation axis of the jet-like feature bisecting the arcs is an effect of projection on the sky plane and that there is no physical jet along the axis of rotation.Comment: 7 pages, 3 figures; version 2; accepted for publication in A&

Considerations concerning fatigue life of metal matrix composites

Since metal matrix composites (MMC) are composed from two very distinct materials each having their own physical and mechanical properties, it is feasible that the fatigue resistance depends on the strength of the weaker constituent. Based on this assumption, isothermal fatigue lives of several MMC's were analyzed utilizing a fatigue life diagram approach. For each MMC, the fatigue life diagram was quantified using the mechanical properties of its constituents. The fatigue life regions controlled by fiber fracture and matrix were also quantitatively defined

Commercial prospects for farming spiny lobsters

Tropical spiny lobsters are fast growing and highly adaptable to captive condition

Overview of lobster farming- Winter School on Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish

Lobsters are high valued seafood with well established export markets around the world and form extremely important fisheries in many countries. World’s production of palinurid lobsters mostly originate from Australia, New Zealand, Cuba, Brazil, South Africa, USA and Mexico. The annual world catch of lobsters is 2, 33,825 t (2005) valued at US $ 2108 million. Total landing of spiny lobsters is 71925 t (2004)

Lobster farming in India

Spiny or rock lobsters are low volume and high value fisheries which support some of the most valuable marine resource worldwide. India, earns an approximate US $ 15 million each year through export of lobsters, mostly to Southeast Asian countries and Japan, although less than, 3,000 tonnes is landed annually. The potential for increasing the yield from the wild fisheries is limited, as the stock is subjected to extreme fishing pressure and is nearing their long term equilibrium yield. Hence, the most imaginative management strategy seems to be increasing the production through population enhancement and aquaculture. Recent success in rearing the phyllosoma larvae, has significantly improved the chances of captive breeding and seed production in spiny lobsters

Sea ranching of spiny lobsters

Sea ranching of spiny lobster

Review of prospects for lobster farming

Capture fisheries have reached a peak in production, and stock enhancement or aquaculture appears to be the only hope of meeting the ever increasing demand for high value seafood like lobsters. For aquaculture, the pressing need is to solve the dilemma of promoting expansion while at the same time demanding the development of environmentally sound technologies and farming practices (Mace, 1997). Lobsters have excellent market demand and price and especially live lobsters are the most preferred. Customers in affluent countries are ready to pay more for fresh seafood. Lobsters are exported in different forms; live, frozen tails, whole frozen, whole-chilled, wholecooked and frozen and as lobster meat. The live lobster trade increased from 1.3 % during 1993-94 to 12.7% during 2003- 04 period

Climate change and its impact on aquaculture. In: Winter School on Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008

The aquatic environment will respond to climate changes in ways that are as equally significant as the responses of the terrestrial and atmospheric environments. The changes may be more gradual and less apparent than those taking place in the atmosphere, because of the ability of the oceans and large water bodies to absorb and distribute heat. Therefore, fluctuations about the mean temperature will tend to be smaller than in the atmosphere. By the same token however, the aquatic ecology will be less tolerant to wide temperature ranges than its terrestrial counterparts, and the rate at which natural habitat changes will challenge the adaptive capacity of species

A Ray-Tracing Model of the Vela Pulsar

In the relativistic plasma surrounding a pulsar, a subluminal ordinary-mode electromagnetic wave will propagate along a magnetic field line. After some distance, it can break free of the field line and escape the magnetosphere to reach an observer. We describe a simple model of pulsar radio emission based on this scenario and find that applying this model to the case of the Vela pulsar reproduces qualitative characteristics of the observed Vela pulse profile.Comment: 23 pages, 9 figures, accepted for publication in Ap