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: Selection and Nitrogen Fixing (N2) Activity Test of Methanotrophic Bacteria from Rice Field Under Different Concentration of Oxygen.
Abstrak: Methanotrophic bacteria is methane oxydizing bacteria. This bacteria has a specific enzyme known as methane monooksigenase (MMO) catalizing reaction of CH4 and O2 to methanol. Methanotrophic bacteria also have ability to fix nitrogen. Methanotrophic bacteria type II and type X could fix nitrogen using nitrogenase enzyme. This enzyme is very sensitive to oxygen. As many as 19 isolates of methanotrophic bacteria was recultured and determined their nitrogen fixation activity at different oxygen concentration. Nitrogen fixation activity was determined by measuring ammonium accumulation in NMS free nitrogen medium. High ammonium accumulation was found at cultures of BGM 1, BGM 3, BGM 5, dan BGM 9 isolates. The highest ammonium accumulation (88,816 <M) was showed by BGM 9 isolate on 30% oxygen concentration and the highest cell density was showed by BGM 5 isolate (OD 0,103) on 80% oxygen concentration. Keyword: Methane, methanotrophic bacteria, nitrogen fixation, Nitrogenase
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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