Judul: Karakterisasi Morfologi dan Pertumbuhan Ubi Kayu ‘Gajah’ Asal Kalimantan Timur Hasil Iradiasi Sinar Gamma
Abstrak: Cassava (Manihot esculenta Crantz.) is one of important food source, therefore it is very important to increase cassava yield and starch content, and decrease HCN content in the tuber through efficient breeding program. High genetic diversity is one requirement in successful breeding program. The objective of this experiment was to increase genetic variability of ‘Gajah’ genotype cassava from East Kalimantan through gamma irradiation. Stem cuttings of cassava were irradiated in PATIR-BATAN and planted in Cikabayan Experimental Field, IPB from December 2012 to June 2013. This research was arranged in randomized completely block design with one factor that was gamma ray irradiation rate. The gamma irradiation rate consisted of five levels i.e. 0, l5, 30, 45, and 60 gray (Gy). The research results showed that the LD20 was 16.04 Gy and the LD50 was 21.49 Gy. Gamma irradiation did not significantly affect the vegetative growth of cassava, but it caused changes in several morphological characters, i.e. pubescence on apical leaves, color of apical leaves, leaves retention, shape of central leaflet, petiole color, number of leaves lobes, and orientation of petiole. One of mutant candidate from 15 Gy-irradiated plants produced 17 tuber per plant, thus it is potentially developed further.
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Judul: Karakterisasi Morfologi dan Pertumbuhan Beberapa Genotipe Ubi Kayu (Manihot esculenta Crantz) Hasil Induksi Mutasi Menggunakan Iradiasi Sinar Gamma
Abstrak: Penelitian ini bertujuan untuk mempelajari pertumbuhan dan keragaman beberapa genotipe ubi kayu yang telah diinduksi iradiasi sinar gamma. Setek batang ubi kayu diiradiasi di Laboratorium Pusat Aplikasi Teknologi Isotop dan Iradiasi (PATIR), Badan Tenaga Nuklir Nasional (BATAN) kemudian ditanam di Kebun Percobaan Cikabayan IPB pada bulan Mei 2012 sampai April 2013. Penelitian dirancang menggunakan rancangan kelompok lengkap teracak (RKLT) dengan dua faktor, faktor pertama yaitu dosis iradiasi sinar gamma yang terdiri atas lima taraf yaitu 0, 15, 30, 45, dan 60 gray, faktor kedua adalah perbedaan genotipe yang terdiri dari Ratim, Jame-jame, UJ5, Malang 4, dan Adira 4. Hasil penelitian menunjukan iradiasi mengakibatkan tanaman mati sebanyak 146 tanaman saat berumur 0-2 bulan setelah tanam (BST). Perlakuan iradiasi mengakibatkan berkurangnya jumlah stomata dan jumlah umbi terhadap beberapa genotype. Perlakuan iradiasi 15 gray menghasilkan tinggi tanaman dan umbi yang lebih besar dibandingkan kontrol dan dosis 30 gray. Hasil karakterisasi menunjukan bahwa perlakuan iradiasi mengakibatkan berubahnya karakter morfologi beberapa genotipe ubi kayu.
Keyword: cassava, characterization, genotypes, morphology, mutations

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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