Application of Homotopy analysis method to fourth-order parabolic partial differential equations

In this paper, by means of the homotopy analysis method (HAM), the solutions of some fourthorder parabolic partial differential equations are exactly obtained in the form of convergent Taylor series. The HAM contains the auxiliary parameter h that provides a convenient way of controlling the convergent region of series solutions. This analytical method is employed to solve linear examples to obtain the exact solutions. The results reveal that the proposed method is very effective and simple

Three-step iterative methods with eighth-order convergence for solving nonlinear equations

A family of eighth-order iterative methods for solution of nonlinear equations is presented. We propose an optimal three-step method with eight-order convergence for finding the simple roots of nonlinear equations by Hermite interpolation method. Per iteration of this method requires two evaluations of the function and two evaluations of its first derivative, which implies that the efficiency index of the developed methods is 1.682. Some numerical examples illustrate that the algorithms are more efficient and performs better than the other methods

Interactive effects of diet protein and water salinity on growth and survival of white leg shrimp (Litopenaeus vannamei Boone 1931)

This study was conducted in the Shrimp Research Center of Bushehr in winter 2005. We treated reared White Leg Shrimp (Litopenaeus vannamei Boone 1931) with five diets containing 20%, 25% ,30%, 35% and 40% protein levels and three salinity levels 15-17ppt, 27-30ppt, and 40-45ppt. We focused on growth, survival, food conversion ratio, hemolymph osmolality, hemolymph protein and corpse protein content. We applied 15 treatments each with three replicates in 45 tanks with 300 liter capacity. Shrimps average weight was about 2 grams at the start and reared after 60 days of culture. Shrimp biomass growth in 15-17 salinity was higher than other salinities showing statistically significant difference with those grew in 40-45ppt salinity (P>0.05). No statistically significant difference was found between growth of the shrimp in 15-17ppt and in 27-30ppt water

Effect of different light regimes on the maturational progress of the whitespotted rabbitfish (Siganus sutor)

In this study, the effects of different light regimes on the reproductive activity of a typical Indo-Pacific coral reef rabbitfish, Siganus sutor, were evaluated. Forty-five adult fish were exposed to nine different photoperiod (8L: 16D, 12L: 12D, 16L: 8D) and light intensity (1000, 2000, 3000 lux) combinations with three replicates and five other fishes reared under indoor light condition (Control). Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) were calculated after 60 days and compared among different experimental regimes in males and females. In the control group, GSI and HSI mean values were 4.67 and 3.24%, respectively, for females and 10.05 and 2.10%, respectively, for males, and these fish showed differences in comparison with the exposed fish. Females kept under 1000 and 2000 lux light intensities had a higher GSI mean value (9.26 and 10.39%, respectively) and also lower average HSI (2.10 and 2.31%, respectively) in 16L: 8D treatment. A similar result was also obtained for males, whereas the 3000 lux light intensity, 8L: 16D day length combination led to more gonadal development (GSIs of 16.41% in females and 12.03% in males). A comparison of results among different photoperiods also confirmed that maturation was induced better in fish maintained under 16L: 8D in both sexes. This investigation revealed the visible role of both photoperiod and light intensity on inducing maturity in the whitespotted rabbitfish, S. sutor. Thus, rearing of adults exposed to an artificial light regime, including 16L: 8D and 2000 lux light intensity, promotes more gonadal development than that occurring in the wild

Growth comparison between post-larvae from cultured and wild spawners of Indian white shrimp, Penaeus indicus, in commercial farms in north Persian Gulf, Bushehr, Iran

Post larvae of wild and cultured spawners of the Indian white shrimp (Penaeus indicus, Milne Edwards, 1837) were reared to market size, in commercial ponds of shrimp farming site of Helleh, in Bushehr Province, during a six months period. Environmental factors, management process and the diet used to feed shrimps were almost similar for both treatments. Averages of the weight, length, specific growth rate, food conversion ratio and survival rate were measured and compared between the two treatments at harvesting time. Results indicated that, the post larvae of wild spawners had better growth, higher survival rate, and lower food conversion ratio. Weight gain of abdominal portion of the body, was higher in wild post larvae (P<0.01), which was in contrast to cephalothorax weight (P<0.01). Length-weight relationship measurements illustrated that, cultured post larvae obtained from wild spawners had similar size and were more acceptable for the market. Broodstock background could be the main reason for given differences, in which, those captured from the sea, had better condition due to receiving appropriate food with higher genetic diversity. To produce high quality post larvae for the expanding shrimp farming industry as an economic activity in the country, it is suggested that broodstocks to be obtained either from the sea as sub-adults or matured spawners, or to be provide from culturing shrimps, raised in conditions closest to the nature (i.e., ambient factors, prepared diets) and also with appropriate genetic diversity

Evaluation of different dietary protein and energy levels on growth performance and body composition of narrow clawed crayfish (Astacus leptodactylus)

Nine practical diets containing increasing percentages of crude protein (CP) and energy (30%, 35%, 40% and 300kcal/100g, 370kcal/100g and 450kcal/100g) were fed to narrow clawed crayfish (mean individual weight=17±2.3 g) during an 8 week feeding trial. Weight Gain, Feed conversion ratio (FCR), Protein Efficiency Ratio (PER), Net Protein Utilization (NPU), Daily Food Consumption (DFC) and body composition of tail-muscle meat of narrow clawed crayfish were determined. At the conclusion of the experiment, comparing the growth parameters in response to interaction between protein and energy levels demonstrated that dietary number 2 (30/370) resulted in higher WG, NPU, PER, and the lowest FCR whereas dietary number 3 (30:450) showed higher SGR and DFC. Comparison of the body composition results indicates the greatest amount of protein absorption in diet number 2 (30/370). Results from this study indicate that narrow clawed crayfish can be fed a practical diet containing 30% protein and 370 Kcal/100gr. Reducing CP levels in narrow clawed crayfish diets may help reduce operating costs and thereby increase producers’ profits

Effects of different levels of energy and protein sources on the growth performance, feeding, survival rate and the chemical body composition of juvenile Pacific white shrimp (Litopenaeus vannamei)

The present study was carried out in order to establish an economical effective diet for the Pacific white shrimp in the southern part conditions of Iran. Three dietary energy levels (E1=262, E2=312, E3=362 Kcal 100 g^-1 diet) and 6 ratios of fish meal (FM): soybean meal (SBM) [(P1= 100% FM+ 0% SBM), (P2= 80% FM+ 20% SBM), (P3= 60% FM+ 40% SBM), (P4= 40% FM+ 60% SBM), (P5= 20% FM+ 80% SBM), (P6= 0% FM+ 100% SBM)], 18 experimental diets were prepared. Completely randomized design was used to assign 54 polyethylene 300 litre round tanks provided by aeration and was stocked by 19 juvenile shrimp as 3 replicates to each treatment. Shrimps average weight was about 0.77 g at the start. After 56 days culture period, maximum growth and nutritional performance were observed in the P6E1 and P5E1 treatments. In addition, the highest survival rate of the shrimps was observed in the P1E1, P1E2, P3E3 and P5E3 treatments. Results indicated that protein, fat, fiber and ash contents of carcase were significantly affected by the treatments (P<0.05). Results of the present study suggest the replacement possibility of at least 80% of dietary fishmeal by soybean meal in the diet of Pacific white shrimp in the conditions of southern part of Iran