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: Bioakumulasi Logam Berat pada Organisme Bentik Pensi (Corbicula moltkiana Prime, 1878) di Danau Maninjau, Sumatra Barat.
Abstrak: Danau Maninjau berpotensi tercemar logam berat yang didalamnya terdapat pensi yang merupakan moluska endemik. Penelitian bertujuan untuk menentukan logam berat (Pb, Cd, dan Cu) pada pensi, kualitas air dan kualitas sedimen, serta hubungan antara ketiganya. Pengambilan contoh dilaksanakan pada bulan Januari hingga Februari 2018. Analisis logam berat menggunakan Atomic Absorption Spectrophotometer (AAS). Logam berat yang tertinggi adalah Cu konsentrasi rata-rata 13,07 mg/kg, konsentrasi Pb rata-rata <0,005 mg/kg, Cd rata-rata 0,13. Nilai MTI (Maximum Tolerable Intake) per bobot orang dewasa (50 kg) yang diperbolehkan mengkonsumsi pensi per minggu berdasarkan konsentrasi Pb, Cd dan Cu masing-masing 312,5 kg, 2,7 kg, dan 13,4 kg. Sedangkan pada anak-anak (15 kg) masing-masing 93,8 kg, 0,8 kg, 4 kg. Konsentrasi rata-rata logam berat Pb, Cd dan Cu pada setiap ulangan di sedimen masih dibawah baku mutu. Konsentrasi logam berat pada pensi lebih tinggi daripada di air, sedangkan konsentrasi logam berat pada pensi rendah daripada di sedimen.
Keyword: air, Danau Maninjau, logam berat, pensi, sedimen

Judul: Modifikasi Algoritme Fungsi Hash Md5 Didasarkan Pada Analisis Syarat Cukup Serangan Diferensial
Abstrak: Salah satu primitif kriptografi modern adalah fungsi hash kriptografi, atau sering disebut fungsi hash satu-arah. Dari segi transformasinya, fungsi hash didefinisikan sebagai fungsi yang memetakan bitstring dengan panjang sebarang ke bitstring dengan panjang tetap. Output dari fungsi hash adalah nilai hash (hash value). Di samping itu, dari segi peranannya di dalam kriptografi, fungsi ini juga diharuskan memenuhi sifat satu arah dan tahan tumbukan. Fungsi hash h dikatakan bersifat satu arah apabila secara komputasi tak layak menentukan input x jika diketahui nilai hash y sehingga y = h(x). Di lain pihak, sifat tahan tumbukan dari h dimaknai secara komputasi tak layak menentukan pasangan input x dan x’ dengan x ≠ x’ sehingga outputnya sama, h(x) = h(x’) (terjadi tumbukan). Sifat satu arah dan tahan tumbukan menyebabkan fungsi hash salah satunya digunakan untuk melindungi integritas data dari pemalsuan. Sebagai ilustrasi, suatu pesan x dilabelkan dengan nilai hashnya y = h(x). Kita bisa memalsukan x apabila kita bisa menentukan pesan lain x’ ≠ x sehingga h(x’) = y (mempunyai label yang sama dengan x). Jika ini yang terjadi maka fungsi hash yang bersangkutan dikatakan tidak aman, dengan kata lain x’ bisa digunakan untuk memalsukan x.
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