Field Identification of Threadfin breams, Silverbellies, Croakers and Bullseye

Nemipterids are one among the most commercially important groups of marine fishes in the tropical Indo-West Pacific region. Family Nemipteridae comprises of five genera: Nemipterus, Parascolopsis, Pentapodus, Scaevius, and Scolopsis. Nemipterus is popularly known as “pink perch”, contributed to 4.78% (1,62,764 t) of the total fish landings in the country during 2015

Geometric dynamical observables in rare gas crystals

We present a detailed description of how a differential geometric approach to Hamiltonian dynamics can be used for determining the existence of a crossover between different dynamical regimes in a realistic system, a model of a rare gas solid. Such a geometric approach allows to locate the energy threshold between weakly and strongly chaotic regimes, and to estimate the largest Lyapunov exponent. We show how standard mehods of classical statistical mechanics, i.e. Monte Carlo simulations, can be used for our computational purposes. Finally we consider a Lennard Jones crystal modeling solid Xenon. The value of the energy threshold turns out to be in excellent agreement with the numerical estimate based on the crossover between slow and fast relaxation to equilibrium obtained in a previous work by molecular dynamics simulations.Comment: RevTeX, 19 pages, 6 PostScript figures, submitted to Phys. Rev.

Energy diffusion in hard-point systems

We investigate the diffusive properties of energy fluctuations in a one-dimensional diatomic chain of hard-point particles interacting through a square--well potential. The evolution of initially localized infinitesimal and finite perturbations is numerically investigated for different density values. All cases belong to the same universality class which can be also interpreted as a Levy walk of the energy with scaling exponent 3/5. The zero-pressure limit is nevertheless exceptional in that normal diffusion is found in tangent space and yet anomalous diffusion with a different rate for perturbations of finite amplitude. The different behaviour of the two classes of perturbations is traced back to the "stable chaos" type of dynamics exhibited by this model. Finally, the effect of an additional internal degree of freedom is investigated, finding that it does not modify the overall scenarioComment: 16 pages, 15 figure

Characterizing dynamics with covariant Lyapunov vectors

A general method to determine covariant Lyapunov vectors in both discrete- and continuous-time dynamical systems is introduced. This allows to address fundamental questions such as the degree of hyperbolicity, which can be quantified in terms of the transversality of these intrinsic vectors. For spatially extended systems, the covariant Lyapunov vectors have localization properties and spatial Fourier spectra qualitatively different from those composing the orthonormalized basis obtained in the standard procedure used to calculate the Lyapunov exponents.Comment: 4 pages, 3 figures, submitted to Physical Review letter

A simulation study of energy transport in the Hamiltonian XY-model

The transport properties of the planar rotator model on a square lattice are analyzed by means of microcanonical and non--equilibrium simulations. Well below the Kosterlitz--Thouless--Berezinskii transition temperature, both approaches consistently indicate that the energy current autocorrelation displays a long--time tail decaying as t^{-1}. This yields a thermal conductivity coefficient which diverges logarithmically with the lattice size. Conversely, conductivity is found to be finite in the high--temperature disordered phase. Simulations close to the transition temperature are insted limited by slow convergence that is presumably due to the slow kinetics of vortex pairs.Comment: Submitted to Journal of Statistical Mechanics: theory and experimen

Chronic neural probe for simultaneous recording of single-unit, multi-unit, and local field potential activity from multiple brain sites

Drug resistant focal epilepsy can be treated by resecting the epileptic focus requiring a precise focus localization using stereoelectroencephalography (SEEG) probes. As commercial SEEG probes offer only a limited spatial resolution, probes of higher channel count and design freedom enabling the incorporation of macro and microelectrodes would help increasing spatial resolution and thus open new perspectives for investigating mechanisms underlying focal epilepsy and its treatment. This work describes a new fabrication process for SEEG probes with materials and dimensions similar to clinical probes enabling recording single neuron activity at high spatial resolution. Polyimide is used as a biocompatible flexible substrate into which platinum electrodes and leads are... The resulting probe features match those of clinically approved devices. Tests in saline solution confirmed the probe stability and functionality. Probes were implanted into the brain of one monkey (Macaca mulatta), trained to perform different motor tasks. Suitable configurations including up to 128 electrode sites allow the recording of task-related neuronal signals. Probes with 32 and 64 electrode sites were implanted in the posterior parietal cortex. Local field potentials and multi-unit activity were recorded as early as one hour after implantation. Stable single-unit activity was achieved for up to 26 days after implantation of a 64-channel probe. All recorded signals showed modulation during task execution. With the novel probes it is possible to record stable biologically relevant data over a time span exceeding the usual time needed for epileptic focus localization in human patients. This is the first time that single units are recorded along cylindrical polyimide probes chronically implanted 22 mm deep into the brain of a monkey, which suggests the potential usefulness of this probe for human applications

Decadal Trends of Indian Demersal Fisheries

Fisheries sector plays an important role in the overall socio-economic development of India. India is one of the major fish producing countries in the world contributing over 3% of both marine and freshwater fishes of the world production. Marine fishes, based on their depth-wise distribution are grouped mainly as pelagic and demersal, the former occupying surface and subsurface waters and the latter the neritic areas in the continental shelf. Demersal fishes are those fishes which can either rest on the sea floor or which can float in the water column just above the sea floor. The demersal fish resources of India include the elasmobranchs, eels, major perches, threadfin breams, silverbellies, sciaenids, lizardfishes, pomfrets, bulls eye, catfishes, flatfishes, goatfish and white fish. There is a significant contribution by the demersal fishes to the total Indian marine fish landings. When compared to the pelagic resources, proper exploitation of the demersal finfishes in India has been initiated since 1960-62 period. With the introduction of mechanized bottom trawling the exploitation of demersal finfishes attained a 2.7 fold increase reaching 0.52 million tonnes in the late eighties from 0.08million tonnes during the late fifties. In 2017, the demersal fish production of India reached new heights with a peak annual average landing of 1 million tonne which is almost an increase of 12.5 fold from the late fifties. The annual average landings of demersal finfishes along the Indian coast during 2010-2015 was accounted to 0.95 million tonnes contributing 26.32% to the total landings. However, the catch share of demersal finfishes during the last 35 years indicates that the contribution of demersal finfishes to the total Indian marine landings is decreasing over the years. The maximum share was reported in 1983 with 33% contribution and the lowest share was in 1989

Field Identification of Major Elasmobranchs along the Indian Coast

Elasmobranchs are an important group of demersal fishes which are represented by sharks, skates and rays. India is the world’s second biggest shark fishing nation next to Indonesia. They belong to the Class Elasmobranchii under the Phylum Chordata. Sharks are caught with various gears like drift gillnets, longlines, hooks and line units and are landed throughout the year. They feed on bony fishes, other sharks, rays, crustaceans and squids