Judul: Potensi antibakteri propolis lebah Trigona spp asal Bogor
Abstrak: Propolis contains resinous substances collected by honey bees from various plant sources. Analysis of numerous samples from different geographic regions led to the disclosure that the chemical composition of propolis is highly variable depends on the specificity of the local flora at the site of collection and thus on the geographic and climatic characteristics of this site. This fact results in the striking diversity of propolis chemical composition, especially of propolis originating from tropical regions. The ethanol extract of Trigona spp propolis collected in Bogor, Indonesia was prepared an assayed to get information about it’s potential ability as antimicrobial substance. Antimicrobial activity was determined by disk diffusion assay. The result of this study shows that the propolis more effective against Gram positive bacterias, Bacillus subtilis and Staphylococcus aureus than Gram negative, E. coli and Pseudomonas aeruginosa. Minimum inhibitory concentration of extract were up to 1.563% against the Gram positive bacterias, and 3.125% against the Gram negative bacterias.
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Judul: Antibacterial Activity of Trigona spp. Bee Propolis From Pandeglang Against Enterobacter sakazakii.
Abstrak: Propolis has many advantages and specific potencies, due to its properties as antibacterial, antivirus, and anticancer. The characteristics and properties of E. sakazakii has been studied well due to its physiological properties and resistances in the environment. The research aim is to determine the propolis potency of Trigona spp as antibacterial agent against E. sakazakii. Propolis was extracted from bee hives of Trigona spp using maceration method with ethanol 70% (propolis extract) yielded 17,76% extract. The antibacterial activity test was performed by a modified agar well diffusion against three isolates of bacteria E. sakazakii IB-19b, IB-29a, and ATCC 35217. Through the initiation test, propolis activity was higher than commercial propolis, and lower than ampicillin. The effectivities of propolis extract to commercial propolis for each isolate IB-19b, IB-29a, and ATCC 35217 were 143,99%, 169,65%, and 155,76% respectively. The effectivities of propolis extract to ampicillin for each isolate IB-19b, IB-29a, and ATCC 35217 were 39,37%, 38,94%, and 47,37% respectively. The minimum inhibition concentration differed for each isolate, the minimum inhibition concentration for IB-19b, IB-29a, and ATCC 35217 were 12,50%, 25,00%, and 50,00% respectively. The propolis activity to each isolate showed the concentration dependent activity, the antibacterial activity decrease as the propolis concentration decrease.
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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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