Judul: Dinamika Kualitas Air Pada Kolam Pemeliharaan Ikan Tengadak (Barbonymus schwanenfeldii Bleeker, 1854)
Abstrak: Tinfoil barb is a freshwater species, which population has been declining because of catch and environmental pollution. An attempt to keep this population is by aquaculture or cultivation. Good water quality was strongly influenced by the optimization of cultivation. This research was aimed to determine the dynamics of water quality and pollution level during cultivation. The research was conducted on nine ponds consisting of three treatments (feeding of 3%, 6%, and 9% of total biomass) with each of three replicates. During the research, the temperature ranged between 22,8 to 26,3 °C; transparancy between 16 to 46 cm; the colours was green to brown; pH between 6,46 to 7,74; DO between 0,7 to 5,29 mg/L; alcalinity between 31,85 to 104,7 mg/L; nitrite between 0 to 0,393mg/L; nitrate between 0,14 to 0,637 mg/L; ammonia between 0,0006 to 0,01 mg/L; ortophosphate between 0 to 0,343 mg/L. Ciapus River water used as an input for the culture had a good pollution level and moderate pollution level. The best water quality was found in feeding of 3% and the best growth rate was found in feeding of 9%.
Keyword: pollution, water quality, tinfoil barb

Judul: Optimasi Salinitas untuk Kelangsungan Hidup dan Pertumbuhan Benih Ikan Tengadak Barbonymus schwanenfeldii
Abstrak: Environmental manipulation techniques are required to increase survival rate and growth of fishes, salinity manipulation is one of them. Salinity directly affects the living organisms life especially in survival rate and growth rate because it is strongly related with their osmoregulation process. The purpose of this research was to determine the optimum salinity for survival rate, growth, and economic profit for nursery activities of tinfoil barb (Barbonymus schwanenfeldii). This research consisted of four treatments of media salinity: 0 ppt (A), 2 ppt (B), 4 ppt (C), and 6 ppt (D). The rearing of tinfoil barb in different salinities showed significant effects on survival rate. Different salinity treatments also showed significant difference on specific growth rate of tinfoil barb.The optimum salinity for tinfoil barb was 4 ppt showed by the highest survival rate at 90%, highest specific growth rate at 1,65%, and highest profit achieved for nursery activities at Rp 139.002 with R/C ratio at 1,12.
Keyword: salinity., specific growth rate, survival rate, tinfoil barb

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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