Effect of stocking density on the production of common carp (Cyprinus carpio Lin.) in cages at Kaptai lake, Bangladesh

Growth, survival and food conversion ratio (FCR) of Cyprinus carpio in cages at different stocking density were studied in Kaptai lake. Fingerlings of common carp (12.47 ± 4.29 g) were stocked at 25/m2 , 50/m2 and 75/m2 each with replication in six floating net cages each of Sm x Sm x 4m and reared for 240 days. The growth rate was inversely related to the stocking density with the mean weights of 325.5 ± 11.74 g, 268.99± 8.44 g and 167.0 ± 11.66 g at low, medium and high densities, respectively. At harvest, standing crop biomass averaged 7 .82, 12.83 and 11.58 kg with the survival of 98.9%, 97.6% and 94.4% and food conversion ratios of 4.51, 3.82 and 4.21 for the above three densities, respectively. Weight gain and production at density 25 fish/m 2 were significantly different (p< 0.01) from other two densities. Water quality was not affected in the cages having different stocking densities

An experimental study of Primary Cosmic Rays at the knee energy region by observation of Extensive Air Showers (EAS)

Simultaneous measurements have been made of the radial (lateral) electron density distribution and the radial muon density distribution at various measured muon energies in the range 2.5–100 GeV in vertically incident EAS in the size range 3.153104 –1.793106 (primary energy range 2.431014 –8.331015 eV) particles detected near sea level. The characteristics of these radial distributions in terms of the measured shower parameters have been determined and used to draw conclusions about the average nuclear mass of the primaries of these EAS

Magneto-transport in a quantum network: Evidence of a mesoscopic switch

We investigate magneto-transport properties of a $\theta$ shaped three-arm mesoscopic ring where the upper and lower sub-rings are threaded by Aharonov-Bohm fluxes $\phi_1$ and $\phi_2$, respectively, within a non-interacting electron picture. A discrete lattice model is used to describe the quantum network in which two outer arms are subjected to binary alloy lattices while the middle arm contains identical atomic sites. It is observed that the presence of the middle arm provides localized states within the band of extended regions and lead to the possibility of switching action from a high conducting state to a low conducting one and vice versa. This behavior is justified by studying persistent current in the network. Both the total current and individual currents in three separate branches are computed by using second-quantized formalism and our idea can be utilized to study magnetic response in any complicated quantum network. The nature of localized eigenstates are also investigated from probability amplitudes at different sites of the quantum device.Comment: 7 pages, 9 figure

Growth and yield of summer groundnut (Arachis hypogaea L.) as influenced by foliar application of water soluble fertilizer

The field experiment was undertaken at the District Seed Farm, Kalyani at Bidhan Chandra Krishi Viswavidyalaya, Nadia, West Bengal during summer season of 2012 and 2013 to study the growth and yield of summer groundnut as influenced by application of water soluble foliar grade fertilizer. Application of liquid grade fertilizerat early growth stage up to 45 DAE did not influence the plant height and dry matter production significantly, but towards maturity varied significantly (P ? 0.05). Crop growth rate was faster at early part of the crop age and gradually slows at later part towards maturity. Foliar application of water soluble fertilizer along with RDF 85% had the significant (P ? 0.05) influence to increase the number of pods per plant, but shelling percentage and hundred kernel weight did not vary significantly. Liquid grade fertilizer either starter dose or booster dose or in both had the positive response to increased the groundnut pod yield up to 4-6 % over RDF only. The crop was equally responsive in increasing the pod yield, when RDF was reduced by 15% along with foliar application of liquid grade fertilizer. The foliar application of water soluble fertilizer was not the substitute to soil applied inorganic fertilizer. Instead, foliar supplementation of nutrients showed positive response to increase the pod yield, in addition to the fertilizers added to soil. Gross return decreased with reduction in amount of RDF applied for the crop, but gross return increased, when water soluble foliar grade inorganic fertilizer was supplemented with RDF. The maximum gross return of `150399 was obtained. The results obtained from correlation analysis carried out to examine the linear relationship between pod yields with different plant characters. Data obtained in case of dry matter of the plant was 0.995 and 0.997 in the respective years at 1% level of significance. Thus, it was concluded that dry matter content of plant is solely responsible over the yield increase in groundnut and foliar application of inorganic fertilizers in addition to that in soil has helped in better adsorption of nutrients in adequate amount by the crop

Effect of metal matrix and foam porosity on thermal performance of latent heat thermal storage for solar thermal power plant

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.In this paper, the thermal performance of latent heat thermal storage system using metal matrix and foam is investigated for the medium temperature (~ 200 ⁰C) and medium power (~1 MW) ORC-based solar thermal power plant. The latent heat storage system using phase change materials (PCMs) is an effective way of storing thermal energy and has the advantage of high-energy storage density which makes the storage system compact. The main drawback of PCMs like molten salts is its low thermal conductivity (~0.2-0.5 W/m.K) which inhibits heat transfer to/from PCM. To overcome this, metal matrix and foam are introduced in PCM as thermal conductivity enhancers (TCE) to improve the heat transfer rate. The volume averaging technique for porous medium is adopted to model the metal foam and matrix embedded in PCM. The fluid flow and phase change in porous medium is modelled using single domain enthalpy–porosity technique. A parametric study is performed to show the effect of porosity of the metal matrix and foam on the outlet temperature of heat transfer (HTF) during charging/ discharging period. It is found that the TES with 0.7 metal matrix and foam porosity performs better than TES with PCM and any other porosity.dc201

Heat transfer enhancement in latent heat thermal energy storage system using fins for solar thermal power plant

Paper presented to the 3rd Southern African Solar Energy Conference, South Africa, 11-13 May, 2015.Thermal energy storage is essential for the solar thermal power plant for the continuous generation of electricity which may be interrupted due to the intermittent nature of solar radiation. In this context, phase change materials (PCMs) can be used as the storage materials because of their high energy density and the ability to store more energy compared to sensible material with a small temperature difference. However, most of the PCMs possess very low thermal conductivity (~0.2–0.5 W/m-k), which severely affects the thermal performance of the storage system. Therefore, it becomes important to improve the effective thermal conductivity of PCMs. In the present study, fin is used as a thermal conductivity enhancer (TCE) to augment heat transfer in PCM. The study numerically investigates the thermal performance of the storage system during melting and solidification with and without PCM. The enthalpy technique is adopted for modeling convection- diffusion phase change in the storage system.dc201

Epidemiology of HIV Infection Among Brothel-based Sex Workers in Kolkata, India

A cross-sectional study was carried out during January-June 2004 to assess the status of HIV infection among brothel-based sex workers in Kolkata city, India. Six hundred and twenty-two sex workers, selected from six brothels, were included in the study to assess their HIV status, and 362 sex workers, a subset of the above population, were interviewed to study their risk behaviour and practices. Blood samples were collected from each sex worker for testing HIV by an unlinked anonymous method. The prevalence of HIV infection was 9.6%, but was much higher among younger sex workers aged 20 years or less (27.7%) compared to the older age group (8.4%). This difference was statistically significant, indicating an association of younger ages with HIV infection [p=0.006 and odds ratio (OR)=4.18; (95% confidence interval (CI) 1.2-13.8)]. HIV was not associated with duration of sex work, average number of clients entertained per day, condom use, practice of sex during menstruation, precoital examination of penis for visible ulcer/discharge, suffering from sexually transmitted infections, and entertaining clients outside the brothel. There was a big gap between the reported and the evaluated condom use by sex workers. The results suggest that there is a need to develop suitable HIV intervention strategies, considering the socioeconomic and cultural aspects of city sex workers, with a provision for continuous monitoring and evaluation

Enhanced orbital electron-capture nuclear decay rate in compact medium

The eigenstate energies of an atom increase under spatial confinement and this effect should also increase the electron density of the orbital electrons at the nucleus thus increasing the decay rate of an electron-capturing radioactive nucleus. We have observed that the orbital electron capture rates of 109In and 110Sn increased by (1.00+-0.17)% and (0.48+-0.25)% respectively when implanted in the small Au lattice versus large Pb lattice. These results have been understood because of the higher compression experienced by the large radioactive atoms due to the spatial confinement in the smaller Au lattice.Comment: 30 pages, 3 Figures, 2 Table