Judul: Kajian Resistensi Lima Varietas Sorgum terhadap Rhyzopertha dominica (F.) (Coeloptera: Bostrichidae).
Abstrak: Sorghum is a cereal crop source of carbohydrate that can be used as a substitute for rice. Sorghum seed storage facing many problems caused by stored product pest, one of them is Rhyzopertha dominica (F.). Damage to sorghum seed caused by insect pests reach 30%. The objective of this research was to evaluate the resistance of five sorghum varieties against R. dominica during storage. Research was conducted at Entomology Laboratory SEAMEO- BIOTROP. Bioassays were conducted by infesting 40 adults of R. dominica to 1000 ml plastic jar containing 100 g sorghum seed for 14 days and then taken out from the jars. All the jars, then incubated for 42 days. Five sorghum varieties tested were Numbu, local Bandung , Local Wonogiri, CTY-33, and B-76. Between day 42-80, all F1 adults came out from the seeds were counted. Resistance level then determined by Dobie Index of Susceptibility (DIS). Weight loss from each variety were also calculated. Research result showed that CTY-33 was the most resistant variety with DIS value of 3.814, seed hardness seemed to be the resistance factor.
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Judul: Kajian Resistensi Lima Varietas Sorgum terhadap Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)
Abstrak: Sorgum merupakan serealia sumber karbohidrat yang dapat dijadikan sebagai substitusi beras. Di tempat penyimpanan, biji sorgum banyak mengalami masalah yang disebabkan oleh hama gudang, salah satunya Rhyzopertha dominica (F.). Kerusakan yang diakibatkan serangga hama gudang mencapai 30%. Tujuan dari penelitian ini adalah mengetahui resistensi lima varietas sorgum terhadap serangan R. dominica selama masa penyimpanan. Penelitian ini dilaksanakan di Laboratorium Entomologi SEAMEO-BIOTROP. Lima varietas sorgum yang diujikan yaitu Numbu, Lokal Bandung, Lokal Wonogiri, CTY-33, dan B-76. Uji resistensi dilakukan dengan menginfestasikan 40 imago R. dominica ke dalam stoples plastik bervolume 1000 ml yang berisi 100 gr biji sorgum selama 14 hari, kemudian seluruh imago dikeluarkan lagi, kemudian seluruh wadah diinkubasi selama 42 hari. Antara hari ke-42-80 seluruh imago F1 yang muncul dikeluarkan kembali dari biji sorgum dan dihitung. Tingkat resistensi biji sorgum didasarkan pada Indeks Kerentanan Dobie (IKD). Hasil penelitian menunjukan bahwa varietas CTY-33 relatif lebih resisten daripada varietas lainnya dengan nilai IKD 3.814, tingkat kekerasan biji sorgum diketahui sebagai faktor resistensi.
Keyword: Bogor Agricultural University, Institut Pertanian Bogor, IPB, Sorghum, Rhyzopertha dominica, Resistance, Dobie index of susceptibility

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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