Judul: Aktivitas Oksidasi Metan dan Reduksi Dinitrogen Oksida (N2O) Kultur Kombinasi Bakteri Metanotrof dan Ochrobactrum anthropi
Abstrak: Methane Oxidation and Nitrous Oxide (N2O) Reduction Activity on Combination Culture of Methanotrophic Bacteria and Ochrobactrum anthropi. Under supervision of IMAN RUSMANA and ALINA AKHDIYA. Rice fields are one source of methane (CH4) and nitrous oxide (N2O) emission. Methanotrophic bacteria and denitrifying bacteria possesing high methane oxidation and N2O reduction activity are very important for controlling CH4 and N2O emission from rice fields. This research was conducted to test the activity of methane oxidation and N2O reduction from four methanotrophic bacteria (BGM 1, BGM 5, BGM 9, and SKM 14 isolates) and two Ochrobactrum anthropi isolates (BL 1 and BL 2 isolates). Six combination were inoculated into Nitrate Mineral Salt (NMS) media mixed with denitrification media, then the activity of methane oxidation, N2O reduction, accumulation of ammonium, nitrite, and nitrate was analyzed. Combination culture E of BGM 1, SKM 14, BL 1, and BL 2 isolates had the highest CH4 oxidation (2,9 x 10-8 ìM/cell/day), N2O reduction activities (0,15 x 10-9 ìM/cell/day), and accumulation of ammonium (19,3 x 10-8 ìM/cell/day) than the other combination cultures. Combination culture of BGM 1, SKM 14, and BL 1 isolates had the highest accumulation of nitrate (17,6 ìM) and combination culture of BGM 5, BGM 9, BL 1, and BL 2 isolates had the highest accumulation of nitrite (10,9 ìM).
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Judul: Efektivitas fiksasi N2 dan oksidasi metan kultur campuran bakteri metanotrof asal sawah
Abstrak: CH4 emissions in a rice field and wetlands is mostly produced by methanogenic bacteria and 80% of the CH4 is oxidized by methanotrophs. Besides of their ability to oxidize methane, methanotrophs also have ability to fix nitrogen. Four selected isolates of methanotrophs which had high nitrogen fixation activity i.e.(BGM 1, BGM 3, BGM 5, and BGM 9 isolates were combined with SKM 14 isolate which had high methane oxidation activity to obtain ideal formulations of the methanotrophs that have high activity of nitrogen fixation and methane oxidation activities. Nitrogen fixation activity was determined by measuring accumulated ammonium in medium and acetylene reduction assay (ARA). The highest concentraion of ammonium on single culture of methanotrophic bacterium was performed BGM 1 isolate (1,86 μM ammonium), and mixed culture of BGM3 and BGM9 isolates had the highest ammonium accumulation (4,905 μM ammonium). The highest nitrogenase activity was performed by mixed culture of BGM1 and SKM14 isolates, it was 11,27 μmol/ml cultures/hour. Whereas the higest methane oxidation was performed by mixed culture of BGM5 and BGM9 isolates, it was 18,20 ppm /ml cultures /day.
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Judul: Pendugaan Cadangan Klaim Asuransi dengan Regresi Fuzzy
Abstrak: Perusahaan asuransi harus menyiapkan cadangan klaim untuk membayar klaim-klaim yang telah terjadi, namun penyelesaiannya tertunda. Waktu penyelesaian dan besarnya klaim yang harus dibayar di periode mendatang tidak diketahui, sehingga perlu dilakukan pendugaan. Salah satu metode untuk menduga cadangan klaim yaitu regresi. Regresi memerlukan banyak data agar dugaannya akurat, tetapi penggunaan banyak data tidak disarankan dalam menduga cadangan klaim sebab data tersebut terlampau jauh dari kondisi sekarang. Regresi fuzzy adalah metode alternatif yang baik dalam menduga dengan data yang sedikit. Dalam karya ilmiah ini dijelaskan cara menduga cadangan klaim dengan regresi fuzzy. Regresi fuzzy melibatkan subjektivitas pembuat keputusan yaitu risk aversion untuk mendapat dugaan berupa nilai dan parameter derajat keanggotaan untuk menentukan dugaan interval besar klaim.
Keyword: claim reserves, fuzzy regression, insurance