Judul: Karakteristik Ketahanan Bakteri Asam Laktat Indigenous Kefir Sebagai Kandidat Bakteri Probiotik Pada Kondisi Saluran Pencernaan in vitro
Abstrak: Functional food containing probiotic bacteria is potential for modification intestine microflora. The objective of this research was to assess the resistance characteristics of kefir indigenous Lactic Acid Bacteria (LAB) (LABs from kefir, Bifidobacterium longum Y-01 and Lactobacillus acidophilus Y-01) as probiotic bacteria through its ability to grow in gastrointestinal conditions such as pH conditions (pH 2, 2.5, 3.2 and 7.2), the presence of bile salts in the small intestine, its resistance to antibiotics (amoxycillin and chloramphenicol) and its microbial activity to inhibit the pathogenic bacteria growth (Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922 and Salmonella Typhimurium ATCC 14028). The results of Gram staining and catalase assay showed that the three kefir indigenous LABs were not contaminated with other microorganisms. Three kefir indigenous LABs had good resistance in gastro intestinal conditions, as the population of all kefir indigenous LABs observed did not decrease when they were exposed to gastrointestinal condition. Kefir indigenous LABs were more resistant to chloramphenicol antibiotics than amoxycillin antibiotics. The antagonistic test of kefir indigenous LABs to pathogen bacteria showed that the three kefir indigenous LABs had a variety inhibition. The statistical analysis showed that different types of LABs had a significant influenced on the inhibition zone of S. aureus, E. coli and S. Typhimurium. Therefore, the three tested kefir indigenous LABs had potential characteristics as probiotic bacteria.
Keyword: 

Judul: Karakteristik Ketahanan Bakteri Asam Laktat Indigenous Dadiah Sebagai Kandidat Probiotik Pada Kondisi Saluran Pencernaan in vitro
Abstrak: Probiotic bacteria defined as living microorganisms which will confer health benefit to the host when administered in adequate amounts. The aims of this research were to study the potential of Lactobacillus plantarum D-01, Lactococcus lactis D-01, Bifidobacterium longum Y-01, and Lactobacillus acidophilius Y-01 as probiotic bacteria through its ability to survive in gastrointestinal conditions (acid conditions of stomach and the presence of bile salts in the small intestine), its resistance to antibiotics, and its antimicrobial properties against pathogen bacterias. This study initiated with assays of four tested Lactic Acid Bacterias for its ability to grow and survive in acid conditions and the presence of bile salts or antibiotics, also its antagonistic activities against indicator strains of pathogen bacterias (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923 and Salmonella Thypimurium ATCC 14028). Result showed the ability of L. plantarum D-01, L. lactis D-01, B. longum Y-01 and L. acidophilus Y-01 to grow in acid conditions and tolerance at the presence of bile salts and antibiotics (t-test). Research found that difference species LABs tested influenced diameter of the inhibition zone against pathogen indicator bacterias (P<0.01). L. acidophilus Y-01 had the largest inhibition zone against S. Thypimurium ATCC 14028 and E. coli ATCC 25922, while B. longum Y-01 was able to produce the largest inhibition zone against S. aureus ATCC 25923 (P<0,05). Based on the characterization of four species LAB, it could be concluded that L. plantarum D-01, L. lactis D-01, B. longum Y-01, and L. acidophilius Y-01 can be used as probiotic.
Keyword: 

Judul: Pricing of Lookback Options with Floating Strike Price Using The Monte Carlo Method
Abstrak: Opsi lookback adalah opsi yang payoff-nya bergantung pada harga saham terbesar atau harga saham terkecil yang dicapai selama masa berlaku opsi. Opsi lookback dikatakan dengan floating strike price jika nilai dari strike price sebesar harga saham pada saat jatuh tempo. Nilai hampiran opsi lookback ditentukan dengan metode Monte Carlo, sedangkan nilai eksak didapat dari nilai simulasi terbesar yang mampu dihitung oleh komputer. Berdasarkan hasil penghitungan, nilai galat relatif yang dihasilkan semakin kecil dengan semakin bertambah banyaknya simulasi yang dilakukan, sehingga metode Monte Carlo untuk menghitung harga opsi lookback dengan floating strike price konvergen ke nilai eksaknya., Lookback option is an option whose payoff depends on the maximum or minimum of the asset price reached during the option period. The lookback option is said to be a floating strike price if the value of the strike price is equal to the stock price at maturity. The value of the lookback option is determined by the Monte Carlo method, while the exact value is obtained from the largest simulation value that the computer can compute. Based on the calculation results, the resulting relative error value get smaller with the increasing number of simulations performed. Therefore, the Monte Carlo method to calculate the price of the lookback option with the floating strike price converges to the exact value.
Keyword: lookback option, floating strike price, Monte Carlo method, convergent