Internal noise driven generalized Langevin equation from a nonlocal continuum model

Starting with a micropolar formulation, known to account for nonlocal microstructural effects at the continuum level, a generalized Langevin equation (GLE) for a particle, describing the predominant motion of a localized region through a single displacement degree-of-freedom (DOF), is derived. The GLE features a memory dependent multiplicative or internal noise, which appears upon recognising that the micro-rotation variables possess randomness owing to an uncertainty principle. Unlike its classical version, the new GLE qualitatively reproduces the experimentally measured fluctuations in the steady-state mean square displacement of scattering centers in a polyvinyl alcohol slab. The origin of the fluctuations is traced to nonlocal spatial interactions within the continuum. A constraint equation, similar to a fluctuation dissipation theorem (FDT), is shown to statistically relate the internal noise to the other parameters in the GLE

Heavy landings of yellowfin tuna Thunnus albacares (Bonnaterre, 1788) by hooks and line off Chennai coast

Tunas are commercially important fish and widely but sparsely distributed throughout the oceans of the world, generally in tropical and temperate waters. They are grouped taxonomically in the family Scombridae, which includes about 50 species. The most important of these in commercial and recreational fisheries are yellowfin (Thunnus albacares) (Fig. 1), skipjack (Katsuwonus pelamis), bluefin tuna (T. tonggol), frigate tuna (Auxis thazard) mackerel tuna (Euthynnus affinis) and striped bonito (T. orientalis). They are exploited mainly by hooks and line, mechanised gillnets and trawlnets in India

Heavy landing of juvenile seerfish Scomberomorus commerson (Lacepede, 1800) along Chennai coast

After the fishing ban (15th April - 30th May, 2011), heavy landings of juvenile seerfish Scomberomorus commerson (Lacepede, 1800) was observed along Chennai coast. During the period from April to August 2011, young ones of S. commerson were landed continuously by gillnet (Pannuvalai). The nets were operated near the shore in 5-10 m depth. The average catch per boat was 15-50 kg dail

बंगाल की खाडी में चेन्नई तट पर पोम्पानो डोल्फिन, कोरिफाइना इक्विसेलिस (लिन्नस, 1758) की पहली रिकोर्ड

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First record of pompano dolphinfish, Coryphaena equiselis (Linnaeus, 1758) off Chennai coast in Bay of Bengal

On 5.9.2009, a catch comprising 15 specimens of pompano dolphinfish, Coryphaena equiselis (Linnaeus, 1758) was landed at Chennai Fisheries Harbour by mechanised gillnet. The mechanised gillnets operated usually at a depth between 30 and 50 m at a distance of 30-40 km north of Chennai towards Andhra Pradesh. Since, trawlnets and mechanised gillnets are the main fishing gears operated off Chennai coast, fishes belonging to the family Coryphaenidae formed part of regular landings by these two gears. Normally common dolphinfish, Coryphaena hippurus formed regular fishery along this coast

Occurrence of a rare species of red crab, Ranina ranina (Linnaeus 1758) along Chennai coast

The red frog crab otherwise called spanner crab is a coastal water species and single representative of genus Ranina under family Raninidea. They prefer to inhabit in bare sandy areas of intertidal and coastal waters of more than 100m depth. Distribution of this crab is confined to tropical and sub topical coastal waters of Indian and Pacific oceans, from the coast of South Africa to Hawaii and the Great Barrier Reef. Occurrence of this species is very sparse in Indian waters and has been recorded once in Gulf of Mannar (Kasinathan et al., 2007)

चेन्नई तट में काँटा डोरियों द्वारा पीत पख टूयूना थन्नस अल्बाकारेस (बोन्नाटेरे, 1788) का भारी अवरण

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Rare occurrence of deepsea snake mackerel off Nagapattinam coast in the Bay of Bengal

Lepidocybium flavobrunneum (Smith, 1843) has a wide distribution in tropical and temperate seas of the world. The species is considered to be benthopelagic in occurrence between 200 and 1000 m, depth, and probably not reported to occur in the northern Indian Ocean. Balasubramanian (2007) reported on the occurrence of this species during 2004-06 in the landings of large meshed gillnets operated off Tuticorin coast in the Gulf of Mannar. A catch of 4 specimens of Lepidocybium flavobrunneum (Fig. 1) belonging to the family Gempylidae (snake mackerels) were observed at Chennai Fisheries Harbour on 5.3.2009