Judul: Dinamika Komunitas Plankton di Kolam Pendederan Ikan Tengadak (Barbonymus schwanenfeldii)
Abstrak: Plankton both phytoplankton and zooplankton is one of essential factor to establishing the success of aquaculture. Artificial feeding in aquaculture may affects the condition of plankton. The plankton can give positive or negative impact to the survival of fish like Tengadak (Barbonymus schwanenfeldii). Plankton observations are expected to provide information about the dynamics of plankton during the fish maintenance. The results of this study indicate that the phytoplankton was dominated by class of Chlorophyceae and the zooplankton was dominated by Rotifera. The value of diversity index tend to moderate, with the value of eveness index tend to high and value of dominance index tend to low for both phytoplankton and zooplankton. Statistical test results by SPSS program showed that the effect of feeding treatment did not affect the composition and abundance of plankton class. In this study, harmful plankton was not found, and was not affected the survival of Tengadak (B. schwanenfeldii).
Keyword: Tengadak (Barbonymus schwanenfeldiii), Plankton, Artificial feed

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: 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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