Judul: Efikasi Beberapa Ekstrak Tanaman untuk Mengendalikan Bean common mosaic virus pada Kacang Panjang di Lapangan
Abstrak: Yard long bean is an important vegetable in Indonesia. One of its production constraint is the infection of Bean common mosaic virus (BCMV). In the field, BCMV infection is difficult to be controlled. One of effort to control the virus is by utilizing antivirus substances from plant origin. The conducted research aim was to test the effectiveness of plant extracts considerably containing antivirus substances to control BCMV on yard long bean in the field trial. Fourteen plants species were applied as crude and protein extracts which were sprayed on the leaves an hour before mechanical inoculation of BCMV. The experiment was arranged by using randomized block design. Each treatment consist of 3 blocks as replicate. Incubation period, disease incidence, symptom, disease severity and titer of BCMV were measured. The result showed that either crude extract or protein extract prolonged the incubation period and decreased the disease severity. Relative inhibition level of severity and BCMV titer of crude extract treatments ranged from 48,4% to 89.8% and from 59.8% to 99.1%, whereas protein extract treatment ranged from 43.2% to 74.4% and from -55.1% to 42.7%, respectively. Crude extract treatment showed more effective to control BCMV infection than protein extract treatment. Among tested plant extracts, Bougainvillea spectabilis and Psidium guajava crude extracts showed highest relative inhibition level of severity and BCMV titer in controlling BCMV in the field.
Keyword: yard long bean, plant extract, BCMV, antivirus

Judul: Seleksi Substansi Antivirus Asal Tanaman dan Efikasinya dalam Mengendalikan Bean common mosaic virus Strain Black eye cowpea (BCMV-BlC) pada Kacang Panjang.
Abstrak: Bean common mosaic virus (BCMV) is an important virus on yard long bean and it is difficult to control. Control efforts by utilizing antiviral substances of plant origin is worthy to studied. The research was done to select and test the effectiveness of plant extracts in suppressing BCMV infection on yard long bean. Twenty two plant extracts were selected by (1) spraying the crude extract to Chenopodium amaranticolor leaves, then plant inoculated by BCMV 1 hour after spraying, and (2) mixturing the crude extract with sap containing BCMV, then inoculated mechanically to C. amaranticolor. Lesio local number and lesio local inhibition percentage are measured. All plant extract treatments were able to reduced lesio local formation significantly in compare to untreatment control. Further, extracts treatment showing highest lesio local inhibition are selected to test the efectiveness in supressing BCMV infecting yard long bean in green house trial. Fifthteen plant extracts which may containing antiviral substances and inducing plant systemic resistance on yard long bean showed that except geranium and red ginger extracts, other plant extract treatments were able to reduced disease incidence and severity, milder symptom, and decreased BCMV titer, respectively. Among tested plant extracts, the most effective in suppressing BCMV infection are Bougainvillea spectabilis , Mirabilis jalapa, and Celosia cristata.
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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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