Judul: Efektivitas Ekstrak Daun Nangka dan Daun Sukun sebagai Moluskisida Nabati terhadap Daya Hidup Keong Mas (Pomacea canaliculata Lamarck)
Abstrak: Golden apple snails (Pomacea canaliculata Lamarck) are pests that attack water plants, especiallypaddy field until 30 days old. One effort to eradicate the snails without leaving chemicals residue in plants is by the provision of natural pesticides such as molluscicides. Jackfruit and breadfruit leaves maybe used as natural molluscicides for snail because they contain saponins. This study aims to test the jackfruit leaf and breadfruit leaf extracts to the survival of snails and determine the effectiveness of the leaf extract based on the LC50. The experiment was conducted separately for small (operculum diameter 5-10 mm) and large golden snails (operculum diameter of 11-20 cm). During the experiment the snails were put in a jars filled with water without leaf extract as the control, and jars with leaf extract at a concentration of 5 g/L, 10 g/L, and 25 g/L as treatments. Observations were carried out by counting the number of snails survives after 24, 48, and 72 hours. The results were analyzed to obtain LC50 values. Jackfruit and breadfruit leaves extracts have potential as molluscicides, since they caused all the snails died on the third day of treatment (72 hours). Decreasing rate of their survival is faster at higher concentrations. The presence of mucus in the body of the dead snails showing symptoms of the effect of saponins. Inconsistent results seem appear on LC50 (24 and 48 hours) of breadfruit extract. LC50 of 24 hours (large snails) and 48 hours (small snails) since they are not detected at the treatment using jackfruit leaves. This suggests the need to redesign the method and the concentration used for better research results.
Keyword: snails., Bogor Agricultural University (IPB), breadfruit, Pomacea canaliculata, Pomacea canaliculata, molluscicides, jackfruit

Judul: Analisis probit untuk pembandingan tingkat toksisitas ekstrak kasar akar tuba dan buah pinang
Abstrak: Golden snail pests become a very important issue in any lowland rice farming. Generally farmers control this pests mechanically by taking existing golden snail. In addition, farmers also use synthetic pesticides to kill golden snail. However, both ways are not effective enough. One way to overcome this problem is to use a plant pesticide tuba root and areca-nut fruit coarse extract. It is known that both of these pesticides can cause death of golden snail. But the effective dose and relative toxicity of the two plant pesticides is not yet known, but it is important to know especially in dealing with critical issues. Determination of effective dose can be done through the determination of the lethal concentration (LC), for example, LC50 and LC90. This research use probit analysis to modeling a connection between golden snail death response (binary data) and both of plant pesticides concentration. Analysis result show that areca-nut coarse extract are more effective than tuba root extract since toxicity level of areca-nut (LC50 = 0.381 g/l and LC90 = 1.098 g/l) higher than tuba root (LC50 = 0.675 g/l and LC90 = 1.182 g/l). Supported by the terms of practically to obtain and how to manufacture, areca-nut coarse extract is recommended for use in eradication of golden snail pests.
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Judul: igenvalues and Eigenvectors of Tridiagonal Matrix with Non Constant and Recurrent Diagonal Entries.
Abstrak: Matriks tridiagonal adalah suatu matriks yang mempunyai entri-entri bernilai nol kecuali pada diagonal utama, di bawah diagonal utama (subdiagonal) dan di atas diagonal utama (superdiagonal). Entri pada diagonal utama tidak konstan dan berulang. Setiap entri pada matriks tridiagonal ini adalah bilangan kompleks. Dalam karya ilmiah ini, akan dibuktikan 3 teorema untuk menentukan nilai eigen dengan 2 kasus dan 1 teorema untuk menentukan vektor eigen. Teorema pertama menentukan polinomial karakteristik dari matriks tridiagonal. Polinomial karakteristik dari matriks tridiagonal tersebut digunakan untuk menentukan nilai eigen pada teorema kedua dan ketiga serta menentukan vektor eigen pada teorema keempat
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