Judul: Preferensi makan dan preferensi peneluran imago Aulacophora similis (Ol.) (Coleoptera chrysomelidae) terhadap tiga jenis tanaman Cucurbitaceae
Abstrak: Tujuan penelitian ini adalah untuk mengetahui prefe- rensi makan dan preferensi peneluran imago A. similis ter- hadap tanaman melon (Cucumis melo L), ketimun (Cucumis sa- tivus L) dan labu siam (Sechium edule W). Penelitian ini dilakukan mulai bulan November 1987 sampai dengan April 1988. Model yang digunakan adalah Rancangan Acak Lengkap. Imago jantan dan betina A. similis lebih menyukai daun tanaman melon sebagai makanannya daripada daun tanam- an ketimun dan labu siam. Imago betina A. similis lebih menyukai tanah dekat tanaman melon untuk meletakkan telur daripada tanah dekat tanaman ketimun dan labu siam.
Keyword: 

Judul: Preferensi Pakan Imago Aulacophora indica (Gmelin) (Coleoptera: Chrysomelidae) terhadap Empat Jenis Tanaman Cucurbitaceae.
Abstrak: Aulacophora indica (Gmelin) is an important beetle attacking on Cucurbitaceae plants. Damage to plants is strongly influenced by the food selection and consumption patterns on leaves. This study aims to examine the feeding preferences of adult A. indica on four types of Cucurbitaceae host plants, namely cucumber (Cucumis sativus), pariah (Momordica charantia), squash (Luffa acutangula), and chayote (Sechium edule); to observe beetles grouping on four types of plants above; to evaluate the behavior of feeding, the concumption capability on preferred food, and the perching behavior during feeding; to count the time and duration of beetles copulation, the timing of oviposition and the number of eggs laid. The food treatments were given to paired adults, separate females, and males beetles in situ. The areal leaf damage was measured everyday. The preference test was conducted for 5 days, while the feeding behavior was observed until 7 weeks after treatments. Results of this experiment showed that the beetles chose a cucumber as a host plant. Area of cucumber leaf consumption by the beetles was 1608.00 mm2 and 2732.40 mm2 inside and outside the laboratory room, respectively. Beetles tended to be more colonized on the upper rather than the lower surfaces of cucumber leaf were 83.53% and 77.03%, respectively. Total consumption of paired A. indica, females and males on cucumber leaves ranged 154.44 to 309.86 mm2/day, 33.27 to 70.50 mm2/day and 27.76 to 46.16 mm2/day. The copulation time of A. indica was occurred between 06:00 am to 05:30 pm. The copulation period spent was 46.00 to 118.54 minutes/day. The females prefered laying eggs in a midday, mostly between 09.30 am to 02.25 pm. Each female laid 51 to 64 eggs/day. The beetles A. indica prefered a cucumber as a host plant and fed optimally on cucumber leaf and could successfully produced eggs during experiment.
Keyword: 

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.
Keyword: