A possible observational bias in the estimation of the virial parameter in virialized clumps

The dynamics of massive clumps, the environment where massive stars originate, is still unclear. Many theories predict that these regions are in a state of near-virial equilibrium, or near energy equi-partition, while others predict that clumps are in a sub-virial state. Observationally, the majority of the massive clumps are in a sub-virial state with a clear anti-correlation between the virial parameter $\alpha_{vir}$ and the mass of the clumps $M_{c}$, which suggests that the more massive objects are also the more gravitationally bound. Although this trend is observed at all scales, from massive clouds down to star-forming cores, theories do not predict it. In this work we show how, starting from virialized clumps, an observational bias is introduced in the specific case where the kinetic and the gravitational energies are estimated in different volumes within clumps and how it can contribute to the spurious $\alpha_{vir}-M_{c}$ anti-correlation in these data. As a result, the observed effective virial parameter $\tilde{\alpha}_{eff}<\alpha_{vir}$, and in some circumstances it might not be representative of the virial state of the observed clumps.Comment: A&A letter, accepte

Interpretation of fish shoal indications in the Arabian Sea

Availability of resources is perhaps one of the most important factors which determines the success of any industry. In the case of the fishing industry, at the basic production level the availability of fishable concentrations of fishes and other marine life is the decisive factor which controls the economy of the whole system

The Indian oil sardine

The Indian oil sardine, Sardinella longiceps Val, supports a neritic pelagic fishery contributing 2 to 33 % of the annual marine fish production in India. Though distributed all along the Indian coast the species sustains a commercial fishery of high magnitude along the coasts of Kerala, Karnataka , Goa and southern part oJ Maharashtra. During the last fifty years the annual all India production oscillated between 14.000 t in 1952 to 3 lakh t during 1968. Presently the west coast indicates a declining trend compared to an ascending pattern along the east coasl. The production from east coast surpassed that of the west coast contributing 52% of the all India production of 2.03 lakh t in 1998. The fishery along the west coast is known for its fiuctuating nature. Further, the species indicates a cyclic pattern of abundance. A variety of traditional gears were engaged in exploiting the resource till the introduction of modern and sophisticated gear like the purse seines in the late seventies and the ring seines in the late eighties. In fact oil sardine is one among the few species that have ever remained a subject matter of intensive research. The focus of this compilation is to present a comprehensive picture of the Indian oil sardine, its fishery, biology, stock, future prospects of exploitation and management measures needed for yield optimisation

Fishery and biology of yellowfin tuna occurring in the coastal fishery in Indian seas

In the recently convened Workshop on "Stock assessment of yellowfin tuna in the Indian Ocean" (FAO/IPTP, 1991) the present status of the fishery, biology and stock structure of yellawfiil tuna taken by different countries bordering the Indian Ocean have been discussed, and recommednations on the development of the fishery for this species made

Ultrafast switching time and third order nonlinear coefficients of microwave treated single walled carbon nanotube suspensions

Microwave treated water soluble and amide functionalized single walled carbon nanotubes have been investigated using femtosecond degenerate pump-probe and nonlinear transmission experiments. The time resolved differential transmission using 75 femtosecond pulse with the central wavelength of 790 nm shows a bi-exponential ultrafast photo-bleaching with time constants of of 160 fs (130 fs) and 920 fs (300 fs) for water soluble (amide functionalized) nanotubes. Open and closed aperture z-scans show saturation absorption and positive (negative) nonlinear refraction for water soluble (amide functionalized) nanotubes. Two photon absorption coefficient,beata ~250 cm/GW (650 cm/GW) and nonlinear index, gamma ~ 15 cm^2/pW (-30 cm^2/pW) are obtained from the theoretical fit in the saturation limit to the data for two types of nanotubes.Comment: 15 pages, 4 figure

Status and scope of research on pelagic fisheries of India

Extensive and indiscriminate exploitation of marine natural resources, during the last three decades is leading to a situation where no more commercial fish stocks may be left in the sea by year 2050 unless ecosystems are protected and the biodiversity is revived, warns a new study cataloging the global collapse of marine ecosystems (Worm et al., 2006). The task of understanding the dynamics of large marine ecosystems to offer effective and relevant scientific advice to develop management interventions is a difficult, complex, expensive and lengthy process. This is especially true in the Indian context where the country has an EEZ of 2.02 million km2, which contributes nearly 40% of the total fish production from the Indian Ocean. Fishes have been mentioned in the ancient literature of India including the epics such as Ramayana and Mahabaratha. Excavations from Mohenjodaro and Harappa indicate that fishing with hooks and nets was common as back as 3000 B.C. and over the years fishing and fisheries in India have evolved at a rapid pace (Ayyappan et al., 2004). Marine fisheries is basically harnessing a natural resource and therefore its management must anchor on knowledge- based interventions generated through close monitoring of their distribution, abundance, exploitation, population dynamics and fluctuations of fish stocks in relation to natural factors and anthropogenic interventions. Against a scenario of an ever-increasing population and stagnant marine fish production in recent years, per capita seafood availability is a serious concern. The countr

Drift gill net fishery for large pelagics at Cochin - A case study on by-catch of pelagic sharks

In India, the elasmobranchs contributed on an average 60,8(X) t during 1986 to 1999 forming 2.7% of the total marine fish landings. The production varied from 50,000t in 1990 to a highest of 75,(X)0 t in 1998. The sharks dominated forming 62.4%, followed by rays (33.5%) and skates the rest. The west coast accounted for 55.5% and east coast 44.5%. The highest contribution of 30.2% was from Gujarat followed by Tamilnadu (26.2%). The drift gillnets, sharing 48.5% of the production, was the major gear, followed by trawls (31.5%) and hooks and line (6.1%). Since the drift gillnets (DGN), apart from the scombroids, exploit a variety of larger pelagics, a case study of the shark fishery by the gear at Kochi was made based on the data from 1979 to 1999 and the results are presented her

On the sei whale Balenoptera borealis Lesson stranded along Palk Bay coast near Pamban light house

A Sei whale got entangled in a gill net operated near Katchathievu on 27-l-'90 at a depth of 8.5 m at about 1900 hrs. Four boats joined together and brought the whale ashore near Pamban Light House on the 28th morning in live condition. Attempts were made to push the whale back into the sea but did not succeed. The medium sized female whale measured 11.4 m in total length and weighed about 7000 kg. The specimen was identified as Balaenoptera borealis Lesson (Fig. 1) and it had 47 throat grooves. The morphometric measurements are give

Hot Core, Outflows and Magnetic Fields in W43-MM1 (G30.79 FIR 10)

We present submillimeter spectral line and dust continuum polarization observations of a remarkable hot core and multiple outflows in the high-mass star-forming region W43-MM1 (G30.79 FIR 10), obtained using the Submillimeter Array (SMA). A temperature of $\sim$ 400 K is estimated for the hot-core using CH$_3$CN (J=19-18) lines, with detections of 11 K-ladder components. The high temperature and the mass estimates for the outflows indicate high-mass star-formation. The continuum polarization pattern shows an ordered distribution, and its orientation over the main outflow appears aligned to the outflow. The derived magnetic field indicates slightly super-critical conditions. While the magnetic and outflow energies are comparable, the B-field orientation appears to have changed from parsec scales to $\sim$ 0.1 pc scales during the core/star-formation process.Comment: accepted, ApJ Letter

Finfish resources around Andaman and Nicobar islands

The average catch rate of finfishes obtained by FORV Sagar Sampada from the survey area in the Andaman Sea was 259 kg/hr and the yield ranged from 8.6 to 1260 kg/hr. Silver bellies was the most abundant component (37.5%) with a catch rate of 96.9 kg/hr. Carangids, elasmobranchs and perches accounted for 20.3%, 11.9% and 8.0% of the total catch and the corresponding catch rates were 52.5, 31.1 and 20.8 kg/hr respectively. The highest catch rate of 1260 kg/hr was recorded from 13°10'N - 92°37'E at a depth of 65m. The catch rate indicated that the depth zone 51-100 m is productive and yielded 84.7% of the total catch at a catch rate of 501.4 kg/hr. Although the pelagic trawl was operated at 38 stations, the catch realised was neghgible (0.83 kg/hr)