Judul: Bioecology of Earthworm Pheretima darnleiensis
Abstrak: Pheretima darnleiensis is a native earthworm in Southeast Asia, India, Japan, and Indonesia, however there is lack of study on P. darnleiensis. Determining the characteristics of P. darnleiensis and the ecology surrounding its habitat is needed in order to culture the earthworm. Hence, this study was aimed to study the structure of several organs and morphological characters that can be used to identify P. darnleiensis and its habitat condition. Earthworms were collected in a plot of 100 x 100 x 20 cm in 10 locations and were identified. The structure of P. darnleiensis organs was studied histologically using paraffin. Pheretima darnleiensis did not have diverticula and stalked gland on copulatory pouches, nephridia occurred on bithecate spermatheca, and the first spermathecal pores were at segment 4/5. Based on this study, the highest population of P. darnleiensis was found in an area containing abundance of other earthworm species at 15 individuals/m2, plant cover at 25.00%, soil arthropods at 16.32 individuals/kg fresh soil, abiotic component cover at 78.50%, soil temperature at 27.42 ± 1.01 oC, soil pH at 5.77 ± 0.53, soil moisture at 19.83 ± 9.92%, organic carbon at 3.39%, N at 0.29%, P at 286.80 ppm, K at 500.00 ppm, sand at 28.76%, silt at 38.74%, and clay at 32.50%. Silt fraction could be considered as one of factors influencing P. darnleiensis abundance.
Keyword: 

Judul: Keanekaragaman Cacing Tanah pada Tipe Habitat dan Ketinggian Tempat yang Berbeda
Abstrak: A research on earthworm diversity was conducted on three types of habitats, the abandoned land, rice fields and horticultural plantations at different heights of Bogor and Bekasi. This study aims to determine earthworm diversity in different habitat and heights. A quadrat measuring 30x30 cm2 was used in 5x5 m2 plot in collecting the earthworm. Ten species of earthworms were obtained in the Bogor region, namely Metaphire houlleti, Pontoscolex corethrurus, Perionyx excavatus, Perionyx sp 1, Eudrilus eugeniae, Dichogaster sp., Glyphidrilus sp., and three unidentified species. Earthworms obtained in Bekasi were also of 10 species, namely Amynthas Agrestis, Metaphire houlleti, Pontoscolex corethrurus, Perionyx excavatus, Perionyx sp 2, Polypheretima elongata, Glyphidrilus sp., and three unidentified species. The highest diversity was in the horticultural plantations (H '= 0.65) for Bogor area. The horticultural plantation in Bogor region also has the highest uniformity index value (E = 0.80), and has the lowest value of Simpson's dominance index (C = 0.56).
Keyword: Bogor Agricultural University (IPB), habitat type, diversity, earthworms

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