Judul: Physico-Chemical Characteristic of Sediment in Teluk Kaping, Bali: It’s Correlation with Bacterial Composition and Abundance.
Abstrak: The objectives of this study were to determine the physico-chemical of the sediment in Teluk Kaping Bali., which is has closed topography and has been utilized for intensive Mari culture activities. Those activities influence the environmental condition. Samples (sediment) in this study came from 16 observation sites. Sediment has a stable characteristic. Its condition could be pointed by the physico-chemical characteristic and the bacterial composition and abundance. Physico-chemical characteristics of the sediment were analyzed using Correlation and Principal Component Analysis, whilst its impact to bacterial composition and abundance were determined using the Multiple Regression. Those analyses were using Minitab 2003 13.2 Version. The physical characteristics showed that the sediment were dominated by sand and clay fraction, meanwhile in the coast area there was also found silt fraction. The pH was alkaline (7.9-8.6). It also has reductive condition, with redox potential between -242.90 mV s/d -56.50 mV. The interstitial water (IW) was 28.85 – 60.49%. Total carbon was (C) 0.13 – 21.6%, nitrogen (N) 0.04 – 0.19%, and phosphor (P) 0.0004 – 0.003%. The C/N/P ratio has a high value, also the C/N ratio has a high value in the sediment, with high ratio variety. C/P ratio variety was higher than the C/N and N/P ratios. Identified bacteria from heterotrophic group, such as Enterobacter spp., Bacillus spp., and Pseudomonas sp., and nitrified bacteria (Nitrosomonas sp., Nitrosococcus sp., and Nitrobacter sp.) were dominantly found in the sediment. Meanwhile, there were also a small number of other identified bacteria from the Enterobacteriaceae group, such as Escherichia coli and Klebsiella sp. Bacillus spp. has the highest abundance, which is almost 60% of total identified bacteria abundance. Heterotrophic bacteria were more dominant than the nitrified bacteria in the sediment. This is related to the ability of the heterotrophic bacteria to utilyze different of nutritional sources, efficiently. It also has a broad environmental tolerancy. Statistical analyses pointed out that the physico-chemical charateristics has unsignificant correlation to the bacterial composition and abundance in Teluk Kaping sediment. This is caused by the characteristic of each bacterium that has an ability and special survival mechanism from limited nutrition and poor environmental condition.
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Judul: Chemical Parameters Distribution in Bojonegara Coastal Water Banten Bay
Abstrak: Penelitian ini bertujuan menganalisis persebaran parameter kimia di Teluk Banten dan menduga hal yang mempengaruhi persebaran tersebut. Parameter kimia kualitas perairan terdiri dari pH, oksigen terlarut (DO), nitrit, nitrat, dan fosfat. Pengambilan sampel air laut dilakukan secara langsung di lapangan (in situ) yang terdiri dari parameter suhu, kecerahan, kedalaman, pH dan DO. Parameter yang tidak dapat dilakukan secara in situ, dilakukan dengan mengambil sampel air untuk diamati di laboratorium (ex situ). Analisis data dilakukan menggunakan aplikasi Surfer untuk membuat sebaran spasial dari parameter yang telah diambil. Sebaran kimia yang dibuat terdapat enam parameter masing-masing dilakukan sebaran pada bulan Januari, Februari, Agustus, September, Oktober 2020 lalu dianalisis berdasarkan hasil sebaran tersebut. Berdasarkan sebaran tersebut dapat dilihat bahwa sebaran parameter kimia pada lokasi penelitian dipengaruhi oleh pengaruh dari arah arus, musim, pasang surut, aktivitas manusia dan industry, selain itu sebaran parameter kimia juga mempengaruhi satu sama lain., This study aims to analize chemical parameters distribution in Banten Bay and guess the factors that influence the distribution. Water quality chemical parameters consist of pH, dissolved oxygen (DO), nitrite, nitrate, and phosphate. Sea water sampling that taken observed in-situ consist temperature, brightness, depth, pH and DO. Parameters that could not be taken observed in—situ then would be done by taken water sample to be taken observed in the laboratory (ex-situ). Data analysis done by using Surfer software to create spasial distribution of the parameters that have been taken. There are 6 chemical parameters distribution and each consist in 5 months which are January, February, August, September, October 2020 and then analyzed based on the distribution results. Based on the distribution, could be seen that chemical parameters distribution in research location influenced by currents, climate, tides, and human and industrial activities. Other than that, chemical parameters distribution could influence each other.
Keyword: Bojonegara Beach, chemical distribution, chemical parameters, physical parameters

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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