Judul: Keterkaitan Antara Unsur Hara Nitrogen (N) dan Fosfor (P) Pada Air Laut, Sedimen dan Serasah Terhadap Tingkat Pertumbuhan Lamun di Kawasan Padang Lamun, Teluk Banten
Abstrak: The study of Seagrass growth had been carried out by using several methods. This experiment studied the differences in nutrient concentrations and resources between seagrass communities on three types of sediments in Banten Bay. Most of the nutrients that are lost by leaf fragmentation are translocated to the sediment surface or into the sedlment. The remaining of the nutrient that is regenerated from leaf fragment deposit is reletsed into the water column. The major portion of nutrient for Seagrass growth is absorbed by the roots. The pore water nutrient contains nitrogen and phosphate. This is p robably due to differences in microbial process that play a role in the N-and P-cycles. It posed that rapid decomposition of plant material through bacterial action produces hi kcpantities of nutrient for Seagrass growth and produces detrital material, which fuels th hain pathway through which primary production is channeled to higher trophic levels. We concluded that the organic material produced from the decaying Seagrass leaves support a complex cycle of Seagrass growt
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Judul: Laju Peluruhan Bakteri Fosfat oleh  Bakteri Sedimen Pada Ekosistem Lamun di Pulau Pramuka, Kepulauan Seribu, DKI Jakarta
Abstrak: Lamun (seagrass) adalah tumbuhan tingkat tinggi berbunga yang dapat tumbuh dengan baik pada lingkungan laut dangkal. Pertumbuhan lamun dipengaruhi oleh beberapa faktor salah satunya nutrien yaitu fosfat. Fosfat di sedimen biasanya tidak bisa digunakan langsung oleh lamun dikarenakan terikat dengan mineral lain sehingga dibutuhkan organisme lain untuk membantu mineralisasi fosfat di alam dan salah satunya adalah bakteri. Penelitian dilakukan untuk mengisolasi bakteri peluruh fosfat pada sedimen serta mengetahui pengaruh laju peluruhan fosfat terhadap kerapatan lamun yang berada di Pulau Pramuka. Hasil isolasi bakteri peluruhan fosfat menggunakan media Pikovskaya diperoleh 28 isolat. Hubungan antara bakteri peluruh fosfat dengan kerapatan lamun dilakukan menggunakan analisis persen korelasi, uji one way ANOVA, regresi linier sederhana serta uji fisiologis untuk mengetahui genus dari bakteri peluruh fosfat. Hasil uji menunjukkan bahwa pengaruh peluruhan fosfat oleh bakteri dengan kerapatan lamun memiliki keterikatan sebesar 16% dan 14%. Korelasi jenis lamun Thallasia hemprichii dan Enhalus acoroides memiliki nilai korelasi yang rendah sementara Cymodocea rotundata serta Halophila ovalis memiliki korelasi kuat. Hasil uji fisiologis diketahui bakteri termasuk dalam genus Pseudomonas dan Actenobacter., Seagrass is a flowering higher plant that can grow well in shallow marine environments. Seagrass growth is influenced by several factors, one of which is nutrients, namely phosphate. Phosphate in sediments usually cannot be used directly by seagrasses because it is bound with other minerals so that other organisms are needed to help mineralize phosphate in nature and one of them is bacteria. The research was conducted to isolate phosphate-degrading bacteria in the sediment and determine the effect of phosphate decay rate on seagrass density in Pramuka Island. The results of isolation of phosphate decay bacteria using pikovskaya media obtained 28 isolates. The relationship between phosphate decay bacteria and seagrass density was carried out using percent correlation analysis, One Way ANOVA test, Simple linear regression, and physiological test to determine. the genus of phosphate decay bacteria. The test results show that the effect of phosphate decay by bacteria with seagrass density has an attachment of 16% and 14%. The correlation of seagrass species Thallasia hemprichii and Enhalus acoroides has a low correlation value while Cymodocea rotundata and Halophila ovalis have a strong correlation. The results of physiological tests showed that the bacteria belonged to the genus psedumonas and actenobacter.
Keyword: Actenobacter, phosphate, phosphate decaying bacteria, physiological, Pseudumonas, seagrass

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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