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

Hormonal Changes Under Altitude Stress

The separate effects of exposure for six hours to cold (8 degree Celsius), hypoxia (4267 m.) and simulated altitude (8 degree Celsius at 4267 m.)have been studied on ten human subjects in a decompression chamber, with respect to the changes in blood cortisol, ADH and urinary catecholamines. Changes in blood cortisol, PBI, ADH urinary excretion of 17-keto steroids and urine volume have been recorded on another ten subjects on acute exposure to high altitude (3505 m.). Changes in the same parameters alongwith urinary testosterone level, have been recorded on another 20 subjects on prolonged exposure for two years to high altitude (3505 m.). The results have been discussed

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

A High Galactic Latitude HI 21cm-line Absorption Survey using the GMRT: I. Observations and Spectra

We have used the Giant Meterwave Radio Telescope (GMRT) to measure the Galactic HI 21-cm line absorption towards 102 extragalactic radio continuum sources, located at high (|b| >15deg.) Galactic latitudes. The Declination coverage of the present survey is Decl. ~ -45deg.. With a mean rms optical depth of ~0.003, this is the most sensitive Galactic HI 21-cm line absorption survey to date. To supplement the absorption data, we have extracted the HI 21-cm line emission profiles towards these 102 lines of sight from the Leiden Dwingeloo Survey of Galactic neutral hydrogen. We have carried out a Gaussian fitting analysis to identify the discrete absorption and emission components in these profiles. In this paper, we present the spectra and the components. A subsequent paper will discuss the interpretation of these results.Comment: 46 pages, Accepted for publication in Journal of Astrophysics & Astronom

The Effect of Third Party Investigation on Pay-Per-Click Advertising

Click fraud is a critical problem in pay-per-click advertising. While both service providers (SPs) and advertisers employ technologies to identify fraudulent clicks, prior work shows that they cannot be induced to make further improvements to their respective technologies. We consider the use of third-party investigation to address this problem and examine whether the responsibility of investigation payments helps induce both parties to work towards improving their technologies unilaterally. Using a principal-agent setting, we show that the advertiser always has incentives to improve his verification technology and the SP will improve his detection technology only when the detection cost is not too large. Given that the cost of detection technology is likely to be small due to the use of inexpensive online filters, our result suggests that third-party investigation helps induce further enhancements to the technologies and is a good mechanism to address the incentive problems in the click fraud setting

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

Length-weight relationships of three reef-associated fishes Lutjanus gibbus, Pinjalo lewisi and Pristipomoides filamentosus off Kochi, southwest coast of India

Length-weight relationships (LWRs) of three reef-associated fishes belonging to the family Lutjanidae viz ., Lutjanus gibbus (Forsskal, 1775), Pinjalo lewisi Randall, Allen & Anderson, 1987 and Pristipomoides filamentosus (Valenciennes, 1830), were estimated based on 548 samples collected from trawl net and hook and line fishery off Kochi, southwest coast of India. Sampling was done at Kochi (Lat. 09°56′327′′N, Long. 76°15′764′′E) and Munambam (Lat. 10°10′965′′N, Long. 76°10′258′′E) landing centers from May 2017 to November 2019. The estimated coefficient (b value) ranged from 2.597 ( P. lewisi , N = 89) to 2.902 (P. filamentosus , N = 240). Coefficient of determination (r2) ranged from 0.906 ( L. gibbus ) to 0.952 ( P. filamentosus), indicating a strong functional LWRs that were highly significant (p <0.001). The study reports the new maximum total length (TLmax) for P. lewisi and also records first estimates of length-weight relationships for three major species of snappers from the region. The generated LWR parameters will be of great importance in evaluating the biological changes in fish stocks and for developing sustainable management measures for snappers in the southeastern Arabian Sea

Large scale harvest of lizardfish juveniles along the Kerala coast

Lizardfishes are one of the major demersal resources, which contribute 5.3% of the total marine landings of Kerala. They are locally known as “Aranameen” and are sold and consumed in fresh and dried condition in Kerala, and support a regular fishery. The lizardfish landings in commercial trawlers along Kerala during the period 2007-2016 was 1,05,848 tonnes (t), with an annual average catch of 10,858 t, which constituted 5.3% of the total marine landings of Kerala

Feasibility Study of Solar Powered Unmanned Aerial Vehicle

High Altitude Long Endurance Unmanned Aerial Vehicles (HALE UAVs) could provide an improved service and/or flexibility at a reduced cost over existing systems for a vast number of civil patrol and surveillance applications. This document looks into the Feasibility and Conceptual Design of Solar Powered UAV for HALE applications. It mentions the advancements in technology of the components required to build an efficient solar powered UAV. It also provides a preliminary design methodology that can be adopted for the conceptual design of Solar Powered UAV. It also emphasizes the Aerodynamic difficulties that are faced in HALE configurations