Suitable stocking density of tilapia in an aquaponic system

An aquaponic system was studied through the integrated culture of mono-sex GIFT and two types of vegetables viz. morning glory, Ipomoea reptans and taro, Colocasia esculenta in a recirculating system for 15 weeks. Tilapia fry of uniform size of 0.76 g were released in three treatments (stocking densities): 106 fish/m³ (T1), 142 fish/m³ (T2) and 177 fish/m³ (T3) to assess the effect of stocking density on the growth performance of fish. Fish were fed with a commercial feed containing 25% protein. Weight gain (g) of tilapia ranged from 19.41 to 32.67 g and was inversely related with stocking density. Percent weight gain varied between 2553.99 and 4298.68% and was significantly different among the treatments. SGR ranged from 3.09 to 3.59% per day and varied significantly. FCR varied from 2.19 to 2.69 and had a positive correlation with stocking density. The highest survival rate (%) was achieved in T1 (99%) followed by T2 (98%) and T3 (96%). Production of fish ranged from 3.43 to 3.52 kg/m³ and was inversely related with stocking density. The present study demonstrated that 106 fish/m³ was the best stocking density in terms of growth, food conversion ratio, survival and production for tilapia culture in the aquaponic system

On the energy-momentum tensor in non-commutative gauge theories

We study the properties of the energy-momentum tensor in non-commutative gauge theories by coupling them to a weak external gravitational field. In particular, we show that the stress tensor of such a theory coincides exactly with that derived from a theory where a Seiberg-Witten map has been implemented (namely, the procedure is commutative). Various other interesting features are also discussed.Comment: 3 page

Prospects of Rice Husk Gasification for Power Generation in Bangladesh

Electricity is the basic requirement to promote socio-economic development. In recent years, Bangladesh is facing severe power crisis all over the country, but the rural areas are the most vulnerable. This acute electricity crisis along with the conventional fuel crunch is affecting every sector of the country and economy is being crippled. To reduce the dependency on fossil fuels, rice husk which are widely abundant agricultural waste from rice industry could play a vital role in this regards. Bangladesh is an agricultural country and produces huge quantity of rice every year. In the year 2011, the total rice production was around 50.63 million tones. Husk is the waste biomass produce during the rice processing, on average it accounts around 20% of the rice produced on weight basis (10.12 million tones). The potential of power generation from rice husk by gasification is around 310 MWe in Bangladesh. The power plant to be installed near the large rice mills `cluster area' in Dinajpur, Bogra, Naogaon, Chapainawabganj and Ishwardi with the surplus rice husk. This paper consolidates information from various studies on the availability of rice husk, its characterization and estimates possible power potential that can be realized

Studies on the induced breeding and post-larval rearing of shing (Heteropneustes fossilis Bloch)

An experiment was conducted on induced breeding and fry rearing of shing, Heteropneustes fossilis (Bloch) in the Department of Aquaculture, Bangladesh Agricultural University for a period of four months from April to July 1994. Hatching rate was calculated at 21.50h and was found to be 45 to 55 % and the survival rate of larvae was 30 to 40 % at 26 to 29°C. Survival rate and growth rate of post larvae were found to be 50 to 60% and 96.6 to 117.2% respectively. Feed-3 (F3) showed the highest survival rate and growth rate of post larvae

Existence of a Semiclassical Approximation in Loop Quantum Gravity

We consider a spherical symmetric black hole in the Schwarzschild metric and apply Bohr-Sommerfeld quantization to determine the energy levels. The canonical partition function is then computed and we show that the entropy coincides with the Bekenstein-Hawking formula when the maximal number of states for the black hole is the same as computed in loop quantum gravity, proving in this case the existence of a semiclassical limit and obtaining an independent derivation of the Barbero-Immirzi parameter.Comment: 6 pages, no figures. Final version accepted for publication in General Relativity and Gravitatio

Economic Evaluation of the PV Micro Utilities Installed by Grameen Shakti for Rural Electrification in Bangladesh

Sharing expensive technology can serve many users, even poor users. Grameen Shakti has developed a special programnamed PV micro utility to make it easier for those who cannot afford SHSs individually. Under this program, GrameenShakti allows people to share the cost and the subsequent benefit of using a SHS. In this study, operation and financialmechanism, analysis of cost of systems, tariff system, simple payback period, NPV and IRR of the micro utility systemshave been analyzed to show the financial viability of PV MU from the PV MU owner’s perspective. Results suggest thatthese systems have simple payback period of around 4-6 years. The NPV of systems varied from 27,000 BDT to 144,000BDT. The levelized electricity cost of PV MU systems is 70 BDT (~0.86 $)/kWh in Bangladesh. The owner has to spendonly 7.50 BDT/day but can earn at least 30-40 BDT per day, and up to 130-200 BDT/day.Keywords - Rural Electrification, Solar PV, Grameen Shakti, Bangladesh, Economic Evaluation

Spintessence: a possible candidate as a driver of the late time cosmic acceleration

In this paper, it is shown completely analytically that a spintessence model can very well serve the purpose of providing an early deceleration and the present day acceleration.Comment: 5 pages, no figure. Accepted for publication in Astrophysics and Space Scienc

Alignment-to-orientation conversion and nuclear quadrupole resonance

The role of alignment-to-orientation conversion (AOC) in nuclear quadrupole resonance (NQR) is discussed. AOC is shown to be the mechanism responsible for the appearance of macroscopic orientation in a sample originally lacking any global polarization. Parallels are drawn between NQR and AOC in atomic physics.Comment: 4 pages, 3 figures, v2: reorganized, Appendix adde