Judul: Pensi (Corbicula Moltkiana, Prime 1878) Population At Lake Maninjau In Related To Its Exploitation And Cage Aquaculture Activities.
Abstrak: Pensi (Corbicula moltkiana, Prime 1878), a species of molluscs (bivalves) of Lake Maninjau, have become one of the local fishery commodities. Cage aquaculture (CA) activity in Lake Maninjau has led to deterioration of pensi habitat and also by ongoing pensi exploitation severely threatened its population. Until now the availability of pensi in Lake Maninjau has not been measured, while the population pressure on either exploitation or environmental degradation continue to take place. Thus the purpose of the research is to study the influence of pensi exploitation and CA activity on pensi population in order to formulate a management plan for pensi utilization in Lake Maninjau. Cage activities in Lake Maninjau spread throughout the shores with the density between "scarce" (<225 units.km-1), "dense" (225-675 units.km-1) until "crowded" (> 675 units.km-1). Sediments substrate in the northern and eastern part of the lake was composed of sand and a mixture of sand and mud; while that in the southern and western part was composed of gravel and rocks. Cluster analysis to anthropogenic parameter water quality show that the conditions throughout the stations were similar (Similarity> 85%). Based of water quality cluster analysis, the CA density were grouped into two levels: "Low" (<675 units km-1) and "High" (> 675 units km-1). T- test to anthropogenic parameter of water quality results levels of COD on Low CA density area were lower than that of High density. However, the levels of other parameter have no significant differences. Level of CA density ("Low" and "High") and the sediment fraction character were set as criteria for pensi population analysis and resulted in three categories of regions: I) High CA density; Soft substrate; II) Low CA density; Soft substrate; and III) Low CA density; Hard substrate. Annual average of pensi abundance was 148-3,994 ind.m-2, the highest were at a depth of 1 m and 3 m, on sandy, and in Low CA density area. The annual production [P] of pensi between 216 - 799 g AFDM m-2 year (y)-1, biomass [B] was 91 – 214 g AFDM m-2 and P/B ratio ranged from 2.02 to 3.73 y-1. The highest production was in Region II, while the lowest production was in Region I. Region I also has the highest coefficient of total mortality (Z) indicated high environmental stress on the pensi population and show high utilization rate or overfishing (E> 0.5). The other regions have a utilization below of its sustainability potency (E < 0.5). Exploitation rate of pensi the whole weight was 42 kg d-1 equal to 12.4 g AFDM d-1 per fishermen. Total exploitation yield of pensi was 111 tons AFDM y-1. Seeing as the potential pensi available was 425 tons AFDM y-1, the utilization rate was lower than sustainably potency (26%). The recruitment of new pensi populations in Lake Maninjau takes place throughout the year in line with frequent findings mature until spawning stage gonad and small size of pensi (<2.5 mm).
Keyword: Corbicula moltkiana, Lake Maninjau, water quality, cage aquaculture, population conditions

Judul: Ecobiology and stock dinamic as a base on management of endemic fish bonti-bonti (Paratherina striata Aurich) in Towuti Lake, South Sulawesi
Abstrak: Bonti-bonti (Paratherina striata), is one of endemic and vulnerable fish in Towuti and Mahalona Lake. It should be protected from decreasing of it population due to habitat quality decline and increasing of exploitation. The objectives of this research is to study the spatial and temporal distribution, growth potency (somatic and reproductive), and relationship between exploitation level and stock ability to recover as base management of the fish. This research was conducted in Towuti Lake, South Sulawesi from May 2006 to April 2007. Samples were collected at five stations using experimental gillnet sized 0.625, 0.75, 1.0, and 1.25 inches and bagan (dipnet). The results show that bonti-bonti is dispersing widely from lakeside to the middle of the lake. The highest abundance of the fish are in inlet with sand, gravel, and stone substrat. The highest temporal distribution of the fish abundance in November and December influenced by dissolved oxygen and high water level. The result of covarian and cluster analysis towards standard morphometric character, could be said that male and female at I, II, III, IV, and V stations is similar tendency or predicted from one fish population. Bonti-bonti is kind of partial spawner fish with peak spawning in May and November. Spawning site, nursery site, and feeding site of the fish are in inlet station. Recruitment of the fish each month with the peak estimated in September, October, and November. Growth pattern of male is Lt=20.05 [1-e-1.7(t+0.02)], while female is Lt=20.45 [1-e-2.0(t+0.01)]. Total length of male and female mature gonad (50%) were 16.78 and 14.61 cm, respectively. Pursuant to growth parameters value and matured fish (50%), growth potency of bonti-bonti is still in good condition. Exploitation level of bonti-bonti stock in Towuti Lake indication to over-fishing (male E=0.54 and female E=0.56). The increasing catch effort (unit/month) of bagan tend to reduce the catch productivity. Decreasing of ability of bonti-bonti stock to recover is not caused by the environmental variables, but caused by over exploitation activity.
Keyword: environmental variables, exploitation activity, catch productivity

Judul: Kombinasi algoritma sha 1 dan algoritma rsa untuk membentuk tanda tangan digital
Abstrak: Tanda tangan digital termasuk ke dalam teknik kriptografi yang memanfaatkan teknologi kunci publik (enkripsi asimetris). Tanda tangan digital dapat dibuat dengan mengkombinasikan teknik hashing (untuk membentuk message digest dari pesan asli) dan enkripsi asimetris (untuk membentuk kunci publik dan kunci privat). Teknik hashing yang digunakan adalah teknik rashing satu arah dengan menggunakan algoritma SHA 1, sedangkan algoritma RSA digunakan untuk enkripsi asimetris Tulisan ini bertujuan untuk mempelajari, menganalisis, dan mengimplementasikan pembentukan dan verifikasi tanda tangan digital menggunakan dua metode, yaitu dengan mengkombinasikan algoritma SHA 1 dan algoritma RSA dan dengan menggunakan algoritma RSA saja. Analisis yang dilakukan pada kedua algoritma ini meliputi analisis algoritma, dan analisis hasil implementasi. Analisis terhadap algoritma SHA | menunjukkan bahwa algoritma ini memiliki kompleksitas O(n) untuk kasus terburuk. Sedangkan untuk pembentukan kunci publik dan kunci privat dengan algoritma RSA diperlukan beberapa algoritma pendukung, yaitu algoritma Miller Rabin, Witness, Euclid, dan Extended Euclid. Semua algoritma pendukung tersebut memiliki kompleksitas waktu yang sama, yaitu O(k), dengan adalah panjang representasi bit bilangan bulat. Kompleksitas waktu yang didapatkan untuk proses pembentukan tanda tangan digital dengan kedua metode ini adalah sama yaitu O(nk). Untuk proses verifikasi, kompleksitas waktu yang didapatkan dengan menggunakan kombinasi dua algoritma adalah O(1 + k) dan untuk algoritma RSA adalah O(n + k). Pada proses pembentukan tanda tangan digital menggunakan kombinasi dua algoritma yang ditandatangani adalah message digest yang dihasilkan oleh algoritma SHA 1, sedangkan pada algoritma RSA yang ditandatangani adalah pesan itu sendiri. Dari hasil implementasi didapatkan untuk proses pembentukan tanda tangan digital menggunakan kombinasi dua algoritma lebih cepat dibandingkan dengan menggunakan algoritma RSA saja untuk file-file yang berukuran besar, dst
Keyword: Tnda Tangan Digital, Teknik Kriptografi, Enskripsi Asimetris