Judul: Relationship between phytoplankton primary productivity and nutrient availability on different levels of clarity in waters off Kendari Bay, Southeast Sulawesi.
Abstrak: The relationship between primary productivity of phytoplankton to the availability of nutrients in the waters of the Bay of Kendari was implemented on April-June 2009 at three sites. The purpose of this research is to examine the relationship between primary productivity of phytoplankton with the abundance and biomass of phytoplankton, and the relationship between primary productivity of phytoplankton with nutrient availability and light intensity at various levels of brightness in the waters of the Bay of Kendari. Based on the data description and laboratory analysis, net primary productivity values during the survey period varied from 2,54 to 11,13 mgC/m3/hour with ranges of average value of NPP from 5,10 to 7,30 mgC/m3/hour. Sampling station located at the middle of the bay had the highest NPP value followed by sampling station positioned at the mouth of the bay and the lowest was found at sampling station located near the river mouth of the upper part of the bay. Relationship between primary productivity and sunlight intensity depicted a strong correlation at the three sampling stations. Relationship of primary productivity to nutrient and light intensity showed that the relationship high on all three stations. The three stations showed similar patterns between the three research stations. At the station mouth of the bay, the three nutrients N (ammonia, nitrate, and nitrite) and light intensity are also factors that provide a real influence on the high and low NPP values while at the middle station and inside the bay, nutrient nitrate with ICM provides a real influence against high and low NPP values in the waters.
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Judul: Study of the dynamic of phytoplankton growth and its relation to variability of solar radiation intensity and dissolved inorganic nutrient in Banten Bay
Abstrak: The growth of phytoplankton in the waters mostly depends on sunlight intensity and dissolved inorganic nutrient present in euphotic zone. This research aimed to count phytoplankton growth including growth rate, doubling time, and generation time, and to analyze growth rate response of phytoplankton to solar radiation intensity and dissolved inorganic nutrient. Measurement of phytoplankton growth was conducted from April to September 2008 at five stations. Station 1 was situated at the mouth river, station 2 at the middle of the Bay toward the beach, station 3 at the middle of the bay, station 4 located at the middle toward outside the bay, and station 5 located outside the bay. Phytoplankton growth at each station was measured at various water depth. At station 1, measurement was done at three euphotic depth namely at 10%, 5%, and 1% from surface irradiance. At station 2, 3, and 4, growth measurement was conducted at 50%, 25%, 10%, and 5% from surface irradiance while at station 5, phytoplankton growth was measured at five euphotic depth namely 50%, 25%, 10%, 5%, and 1% from surface irradiance. Research result showed that phytoplankton growth occurred faster at intermediate light intensity and intermediate concentration of dissolved inorganic nutrient. However, the role of light intensity and dissolved inorganic nutrient in controlling phytoplankton growth was not synergic. Temporally, light intensity did not really control the growth of phytoplankton as compared to dissolved inorganic nutrient in term of DSi because sunlight intensity from April to September was relatively stable compared to DSi that tended to be various. Spatially, on the other hand, light intensity and dissolved inorganic nutrient in term of DIN, DIP, and DSi simultaneously controlled phytoplankton growth. This occurred due to light intensity was varied and tended to be homogenous from station 1 to station 4 and low at station 5. Different phenomena also occurred with DIN, DIP, and DSI which was varied and tended to be higher at station 1 and homogenous at station 1 to station 4. However, DSi tended to be more varied than DIN and DIP. Based on this finding, it was stated that DSi was more dominant in controlling phytoplankton growth in Banten Bay and categorized as fast growth rate ranging from 0.66-2.44 day-1, doubling time 0.34-2.04.day-1, and generation time ranging from 0.91-3.53 day-1.
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Judul: Konstruksi aritmetika kurva eliptik F(2m) supersingular dan non-supersingular untuk skema kunci publik ElGamal
Abstrak: Algoritme ElGamal adalah salah satu algoritme kunci publik dengan aritmetik modular p yang mempunyai struktur grip siklik Z(p). Tingkat keanaman algoritme ini terletak pada pemecahan masalah logaritme diskret dari Z(p). Akan tetapi, tingkat keamanan tadi tahun ke tahun semakin menurun yang disebabkan kemampuan pemecahan algoritme diskret semakin meningkat. Untuk memenuhi tingkat keamanan yang memadai dibutuhkan p yang cukup besar yang menyebabkan proses enkripsi dan dekripsi menjadi lambat.
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