Insights on diet dynamics of Indian mackerel Rastrelliger kanagurta (Cuvier, 1816)

The diet of Indian mackerel Rastrelliger kanagurta (Cuvier, 1816) is reported based on the gut content analysis of specimens collected along the central Kerala coast, India. The study indicated ontogenetic variations in diet with diet breadth being highest in the largest size class of >231 mm total length (TL). Copepods followed by diatoms were the preferred food items. Detritus was an important diet component, especially during the pre-monsoon season and in the larger (>231 mm TL) size groups. The Preponderal Index (Ip) indicated seasonal differences in proportions of the various prey consumed. Spearman Rank Correlation Coefficient indicated similar diet quality during monsoon (June-September) and post-monsoon (October-January) seasons; but significant differences as compared to pre-monsoon season (February-May). Based on the results of the study, Indian mackerel was classified as an opportunistic feeder with a diet component that broadly reflects its seasonal-spatial habitats and local food availabilit

Fatty acid signatures of the Indian mackerel Rastrelliger kanagurta (Cuvier)from the Arabian Sea along the Indian coast

The fatty acid profile of the Indian mackerel Rastrelliger kanagurta from the Arabian Sea was studied in relation to its maturation and spawning cycle. Among fatty acids, polyunsaturated fatty acids (PUFA) component was the highest (46.9%) followed by saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) at 41.8% and 11% respectively. No differences were observed between the period of low spawning activity in January and peak spawning activity in May. However significant (p<0.05) differences were observed with regard to sex where females had higher levels of SFA and MUFA while males had higher levels of PUFA. With regard to maturity stages, only females showed significant differences (p<0.05) in MUFA content with higher level in mature stages compared to immature stages. Docosahexaenoic acid (DHA) was the single largest component of PUFA. The absence of marked temperature differences in the Arabian Sea probably precludes seasonal effects on the levels of SFA, MUFA and PUFA in the Indian mackerel while variations of individual FA within these groups indicate lipid dynamics in relation to reproduction and feeding

On the Origin of the Wide HI Absorption Line Toward Sgr A*

We have imaged a region of about 5' extent surrounding Sgr A* in the HI 21 cm-line absorption using the Very Large Array. A Gaussian decomposition of the optical depth spectra at positions within about 2' (approx. 5 pc at 8.5 kpc) of Sgr A* detects a wide line underlying the many narrow absorption lines. The wide line has a mean peak optical depth of 0.32 +/- 0.12 centered at a mean velocity of V(lsr) = -4 +/- 15 km/s. The mean full width at half maximum is 119 +/- 42 km/s. Such a wide line is absent in the spectra at positions beyond about 2' from Sgr A*. The position-velocity diagrams in optical depth reveal that the wide line originates in various components of the circumnuclear disk (radius approx. 1.3') surrounding Sgr A*. These components contribute to the optical depth of the wide line in different velocity ranges. The position-velocity diagrams do not reveal any diffuse feature which could be attributed to a large number of HI clouds along the line of sight to Sgr A*. Consequently, the wide line has no implications either to a global population of shocked HI clouds in the Galaxy or to the energetics of the interstellar medium as was earlier thought.Comment: LaTeX, 12 pages and 9 figures, accepted for publication in J. Astrophys. Ast

Mechanical Failure Analysis of Needles, for Micro-needle Array Dry-electrodes

 Dry electrodes, which have an array of vertically aligned conducting micro-needles over a conducting substrate/base are most suitable for long-term continuous monitoring of EEG-signal, and overcomesthe disadvantages of conventional wet electrodes. A crucial design requirement for thesemicro-needlearrays, is the choice of the needle material with suitable mechanical strength to penetrate the skin without mechanical failure. This paper gives, the results of mechanical failure analysis of different needle materials that have been typically used/proposed for invasive use. A conical needle with 150μ width at the base and 10μ width at the tip, and length in the range 10μ - 200μ was taken up for calculation. The Critical load for failure, falls in the following descending order for the selected materials: viz., Carbon Nanofibre (CNF), Titanium-alloy (Ti 6-4), Single Crystal Silicon, Nickel, Tungsten, Platinum-Iridium (Pt90 percent-Ir10 percent), Stainless Steel (SS304),Poly Methyl Methacrylate (PMMA), Polyimide, Polycarbonate, Gold, Silver, Photoresist-SU8, Polyurethane and Poly DiMethylSiloxane (PDMS).Taking the most accepted value of 0.1N as the penetration force required for needle penetration into skin, it is seen that for a needle length of 100μ, the following materials, Carbon Nanofibre (CNF), Titanium-alloy (Ti 6-4), Single Crystal Silicon, Nickel, Tungsten, Platinum -Iridium (Pt90 percent-Ir10 percent) andStainless Steel (SS304), can penetrate the skin without mechanical failure

Modeling and control of a real time shell and tube heat exchanger

Process industries generate large amount of heat that needs to be transferred. Shell and tube heat exchangers are extensively used in industries for utilization of the heat energy generated from different processes. For definite utilization of this energy, the temperatures of the hot and cold fluids passing through the heat exchanger should be monitored and controlled efficiently. A proper model of heat exchanger is required for the purpose of monitoring and control. The objective of the paper is to mathematically model the heat exchanger using system identification methods and experimentally evaluate the effectiveness of two PID controller tuning methods such as Internal Model Control (IMC) and relay auto-tuning for temperature control. The Auto Regressive-Moving-Average model with eXogenous inputs (ARMAX) model of the heat exchanger is obtained from the Pseudo Random Binary Signal (PRBS) experiment performed on the heat exchanger system. The outlet temperature of the cold fluid is considered as the controlled variable. Based on the obtained model, PID settings are designed using the two tuning methods, and the closed loop responses such as servo and regulatory are compared experimentally. It is seen from the experimental results that the IMC based controller shows better results than the relay auto tuning method in terms of time integral error (i.e., ISE and ITAE)

The Sasa-Satsuma higher order nonlinear Schrodinger equation and its bilinearization and multi-soliton solutions

Higher order and multicomponent generalizations of the nonlinear Schrodinger equation are important in various applications, e.g., in optics. One of these equations, the integrable Sasa-Satsuma equation, has particularly interesting soliton solutions. Unfortunately the construction of multi-soliton solutions to this equation presents difficulties due to its complicated bilinearization. We discuss briefly some previous attempts and then give the correct bilinearization based on the interpretation of the Sasa-Satsuma equation as a reduction of the three-component Kadomtsev-Petvishvili hierarchy. In the process we also get bilinearizations and multi-soliton formulae for a two component generalization of the Sasa-Satsuma equation (the Yajima-Oikawa-Tasgal-Potasek model), and for a (2+1)-dimensional generalization.Comment: 13 pages in RevTex, added reference

मेबे मोती उत्पादन-आंडमान और निकोबार द्वीप समूह में एक नए उद्योग के विकास की प्रत्याशाएं

कृपया पूरा लेखा पढ

Transport of flexible chiral objects in a uniform shear flow

The transport of slightly deformable chiral objects in a uniform shear flow is investigated. Depending on the equilibrium configuration one finds up to four different asymptotic states that can be distinguished by a lateral drift velocity of their center of mass, a rotational motion about the center of mass and deformations of the object. These deformations influence the magnitudes of the principal axes of the second moment tensor of the considered object and also modify a scalar index characterizing its chirality. Moreover, the deformations induced by the shear flow are essential for the phenomenon of dynamical symmetry breaking: Objects that are achiral under equilibrium conditions may dynamically acquire chirality and consequently experience a drift in the lateral direction.Comment: 25 pages, 16 figure

चेन्नई और नीण्डकरा बन्दरगाह में अवतरित ब्राकिचूरन कर्कटों की जैवविविधता – एक झलक

कृपया पूरा लेखा पढ