Judul: The Effect of Tin Mining on the Diversity of River Fish and Indigenous Knowledge of Local Community in Bangka Island.
Abstrak: Tin mining operation in Bangka significantly damages the aquatic environment, especially the water quality, river fish habitat, and diversity of fish resources. The objective of the research is to analyze the effects of tin mining operations on water quality, fish species diversity, and indigenous knowledge related to the protection and use of river ecosystem. The research was conducted from February to May 2013 in two rivers, the Menduk River - represent river under influenced of tin mining operation - and the Jeruk River represent without tin mining operation. Water quality parameters that measured among others were stream velocity, temperature, brightness, turbidity, TDS (Total Dissolved Solids), TSS (Total Suspended Solids), pH, alkalinity, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD5), and heavy metals (Pb, Zn, Cu, Sn). Fish sampling was carried out by using gill nets with mesh sizes ¾ inch, 1 inch and 1½ inch. Further, a ladle, tangkul and traps are also applied for enriching the fish biodiversity data. Based on water quality data, a Pollution Index (PI) was calculated. Furthermore, a habitat index was analyzed to measure the disturbances of the river habitat. Social aspects are measured through interviews and observations to community leaders and relevant stakeholders. The result shows that, first, the tin mining operations affects is significantly the water quality of the upstream of Menduk River where the mining site are located. The quality of brightness, turbidity and TSS of the upstream river are lower compare to the downstream areas. Furthermore, the water quality along the upstream to downstream of Menduk River is significantly lower than the Jeruk River as shown in the Menduk’s PI that reach 4.2 meanwhile the Jeruk’s PI 1.2. Second, those mentioned habitat changing of the Menduk River, more over affect to the fish diversity. Under disturbed habitat, the fish diversity of Menduk’s river comprise only of 21 species from 10 families. It is different significantly with the relatively undisturbed habitat of Jeruk River where the fish diversity reached 36 species from 16 families. Third, the local community surround both rivers are still maintaining the indigenous knowledge and rules for protecting and sustainable use of rivers and its fish aquatic resource. The elder (dukun) has authority to enforce rules and sanctions and the community members complies the rules. However, since most of the illegal tin mining operated by migrants from outside Bangka Island, the local knowledge, wisdom and local rules are not obey by the migrants.
Keyword: water pollution, freshwater fish biodiversity, tin mining, Indigenous Knowledge, Bangka Island

Judul: Kajian Awal Potensi Tumbuhan Indigenous dan Keragaman Funginya untuk Revegetasi Lahan Bekas Tambang Timah di Pulau Bangka
Abstrak: Activity of tin mining had negative impact on the ecosystem including decreasing in soil fertility. Effort had been done to revegetate the post tin mining land, however, the plant used was mainly Acacia mangium. This because the plant was ease to grow in marginal land, including post tin mining site. The potential indigenous plant is defined as indigenous plants that have potency to be used in revegetation program of the post tin mining land. The objective of this research was to examine the potency of indigenous plants and diversity of fungi that were associated with the potential plant for revegetation program of post tin mining land. Five experimental sites were selected, they were revegetated lands of 0 year (Jongkong 5E), 3 years (Jongkong 24), 16 years (Jongkong1), and 28 years (Nibung 2), and secondary forest as a control treatment. The parameters mesuared for determining the potency of indigenous plants were Important Value Index, production and decomposition rate of litter fall. The soil characteristics that were determined plant growth such as physical and chemical properties were also measured. Litter fall analysis was carried out based on predominant tree found in all sites. Fungal diversity was studied by isolation and identification of the fungi grown in roots, leaf litters, and rhizosfers. The vegetation analysis showed that the plants were grow in all research sites were Dyera costulata, Schima wallichii, and Acacia mangium. The production and decomposition rate of litter fallnin all sites were varied. The production of litter fall from Acacia mangium in Jongkong 1 was 3.79x10-4 ton/ha/year. The highest decomposition rate of litter fall was found Nibung 2 from Dyera costulata was 16.36/year with residience time 0.06 years. The fungal diversity isolated from dominant vegetation in tree stage category was high. The average of each plant harboured 26-30 fungi that were grown in roots, leaf litters, and rhizosfers of the plants. Trichoderma was the dominant fungi. Based on the data of vegetation analysis, production and decomposition rate of litter fall and fungal diversity, Dyera costulata and Schima wallichii were the potentional plants for revegetation program of post tin mining land.
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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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