Judul: Penapisan Aktifitas Antibakteri Ekstrak Etil Asetat Sianobakteri
Abstrak: Penelitian ini bertujuan mencari isolat sianobakteri yang memiliki aktifitas ekstrak paling baik dalam menghambat pertumbuhan Escerichia coli dan Micrococcus luteus secara in vitro. Etil asetat digunakan sebagai pelarut untuk ekstraksi biomassa sianobakteri. Dua puluh empat ekstrak etil asetat sianobakteri dapat menghambat pertumbuhan bakteri. Ekstrak dari isolat Lipi-F-001 dan Lipi-F-005 secara konsisten memiliki % daya hambat paling baik terhadap E.coli dan M.luteus. Pada konsentrasi 0.02 mg/mL, ekstrak dari isolat Lipi-F-001 memiliki % daya hambat sebesar 98.89% terhadap E.coli dan 59.33% terhadap M.luteus, dan % daya hambat untuk Lipi-F-005 sebesar 63.05 % terhadap E.coli dan terhadap 27.00 % M.luteus . Isolat Lipi-F-001 diduga merupakan Arthronema sp dan Isolat Lipi-F-005 diduga merupakan Leptolyngbya sp.
Keyword: Antibakteri, sianobakteri, Arthronema sp., Leptolyngbya sp.

Judul: Penapisan Aktivitas Antibakteri Ekstrak Aseton Sianobakteria.
Abstrak: Sianobakteria adalah kelompok prokariota fotoautotropik Gram-negatif yang memiliki sifat-sifat bakterial dan tanaman. Sianobakteria diketahui memiliki aktivitas antibakteri. Pada penelitian ini dilakukan penapisan isolat sianobakteria yang berpotensi untuk antibakteri terhadap bakteri Gram negatif dan Gram positif. Ekstraksi aseton dipilih dengan maksud memperoleh senyawa aktif polar dari isolat yang diuji. Hasil penelitian menunjukan bahwa seluruh ekstrak yang diuji dapat menghambat pertumbuhan bakteri Gram negatif dan Gram positif. Isolat LIPI-F-32 dan LIPI-F-59 memiliki daya hambat paling tinggi terhadap bakteri Escherichia coli yaitu sebesar 90.59% pada konsentrasi 0.05 mg/mL untuk isolat LIPI-F-32 dan 94.85% pada konsentrasi 0.2 mg/mL untuk isolat LIPI-F-59. Sedangkan daya hambat tertinggi pada bakteri Micrococcus luteus didapat dari LIPI-F-44 dan LIPI-F-45 dengan daya hambat sebesar 88.40 % dan 83.66% pada konsentrasi 0.2 mg/mL. Isolat isolat ini termasuk ke dalam ordo Chrooccoccales. Isolat LIPI-F-31 dan LIPI-F-45 mampu menghambat bakteri Escherichia coli dan Micrococcus luteus dengan persen daya hambat yang tinggi. Sehingga isolat isolat ini dapat dilanjutkan untuk penelitian selanjutnya.
Keyword: Antibakteri, aseton, Chroococcales, sianobakteria

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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