Judul: Komunitas Staphylinidae (Coleoptera) di Kebun Ubi Jalar
Abstrak: Staphylinidae is a member of order Coleoptera (beetle). This family characterized by elongated slender body, large abdominal section and tapered end of the abdomen, and very short elitra. Most of staphylinids role as predators, saprofag, polifag, and as bioindicators of soil fertility. This research aimed to study the community of staphylinids in the sweet potato fields at Bogor. Observations and collections of beetle were done by using road sampling method. Samples collected were preserved in the ethanol 70% for identification purposes. Environmental factors, i.e. air temperature, humidity, and light intensity were measured during observations of beetles. Result showed that the community of staphylinids found in the sweet potato fields were Paederus fuscipes (subfamili Paederinae), Medon sp. (subfamili Paederinae), and Stenus sp. (subfamili Steninae). The dominant staphylinid species in the sweet potato was P. fuscipes
Keyword: Community, Coleoptera, staphylinid, sweet potato fields.

Judul: Keanekaragaman dan Kelimpahan Spesies Staphylinid (Coleoptera) di Habitat Persawahan Sekitar Bogor
Abstrak: Staphylinid beetles (order Coleoptera) are characterized by elongated and slender body shape, short elytra that covered some segments of the abdomen, and body usually shiny black, brown, or yellow-brown. In the paddy field ecosystem, these beetles are known as predator. This research aimed to measure the diversity and abundance of staphylinid beetles in the paddy field at some areas in Bogor. The research also studied the hemolymph structure of Paederus fuscipes. Collections of beetle were done by using road sampling method in some paddy fields. Observations of hemolymph structure were done by making a blood smear. Staphylinid beetles found in six paddy fields in Bogor were Paederus fuscipes (subfamily Paederinae), Stenus sp. (subfamily Steninae), Hypostenus arachnoides (subfamily Steninae), and Astenus lombokianus (subfamily Paederinae). Diversity of staphylinid species in paddy fields is low. The most dominant species staphylinid at the paddy fields was P. fuscipes. Hemocytes type found in the hemolymph of P. fuscipes beetles were prohemocyte, plasmatocyte, adipohemocyte, and cystocyte.
Keyword: Bogor Agricultural University (IPB), staphylinid., paddy fields, hemocyte, diversity, Dominance

Judul: The Effects of Variance of Interest rate to Variance of Annuity Future Values
Abstrak: Time value of money is a concept that refers to the difference of the value of money due to time difference. The value of money for present time would not be the same as the value of money in the future. The value of money for present time is called as Present Value (PV) of the money and the value of money for future time is called Future Value (FV) of the money. Determination the value of money, for present and future time, depends on the time and rate of return. The value of money is determined by several factors such as inflation, fluctuation of interest rates, and government policy in securities and taxation. Due to fluctuation of the value of money we need a FV formulation, it is useful for knowing whether an investment can be profitable or not, and this information is useful also in budget analysis. Annuity is defined as a series of payments made for a specific period. The payment, fixed or varied, can be made at the beginning or at the end of the period. Annuity paid at the beginning of the period is called annuity-due and annuity paid at the end of the period is called immediate annuity-certain. The accumulated value of the annuity after few years later is called as a final value or a future value. Burnecki et al. (2003) have discussed about the FV of a fixed-rate annuity in which payments are made according to the arithmetic or geometric series. They have also examined FV for annuities in which payments are made according to arithmetic or geometric series with random rates of interest. This paper examines FV for annuity-due in which payments are made according to arithmetic or geometric series with interest rates as a random variable, which is normal distribution ,  . Future value formula is expressed in recursive form. FV for annuity-due which payments are made according to the arithmetic or geometric series with random rates of interest is calculated by theoretical way and simulation way. The random rates of interest is denoted as k k i  i  , where k i an independent random variable; i is a constant and k  is a random variable which has normal distribution ,  . By using the determined parameters, a sequence of random rates of interest are generated for theoretical calculation. Meanwhile for the simulation, the random rates of interest is generated 1000 times for the simulation. The generated data give mean value, variance, and standard deviation. Moreover, error of mean value, variance, and standard deviation from the theoretical and simulation results are calculated. Error calculation uses Symmetric Mean Absolute Percentage Error (SMAPE). The smaller the value of SMAPE is the more accurate the simulation. The interest rate variances are varied from 0.000036 to 0.0001 to study the relationship between variance of rates of interest and variance of future value. The theoretical and simulation results show that when the variance of random rates of interest increases, then the variance of FV increases linearly. FV of the annuity-due in
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