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: Efikasi Beberapa Ekstrak Tanaman untuk Mengendalikan Bean common mosaic virus pada Kacang Panjang di Lapangan
Abstrak: Kacang panjang merupakan sayuran penting di Indonesia. Salah satu faktor pembatas produksi kacang panjang adalah adanya infeksi Bean common mosaic virus (BCMV). Di lapangan, infeksi BCMV sulit untuk dikendalikan. Salah satu upaya pengendalian virus tanaman adalah dengan memanfaatkan ekstrak tanaman yang mengandung substansi antivirus. Penelitian ini bertujuan untuk mengetahui keefektifan beberapa ekstrak tanaman yang diduga memiliki substansi antivirus untuk mengendalikan BCMV pada kacang panjang di lapangan. Empat belas ekstrak tanaman terpilih diaplikasikan dalam bentuk ekstrak kasar dan ekstrak protein yang disemprotkan ke daun satu jam sebelum inokulasi mekanis BCMV. Percobaan dirancang dengan RAK dan tiap perlakuan terdiri dari 3 blok sebagai ulangan. Peubah yang diamati adalah waktu inkubasi, kejadian penyakit, gejala, keparahan penyakit dan titer BCMV yang dideteksi secara serologi. Hasil penelitian menunjukkan bahwa baik perlakuan ekstrak kasar maupun protein memperpanjang waktu inkubasi dan menekan keparahan penyakit. Tingkat hambatan relatif keparahan dan titer BCMV perlakuan ekstrak kasar berturut-turut sebesar 48,4% - 89.8% dan 59.8% - 99.1%, sedangkan pada perlakuan ekstrak protein berturut-turut sebesar 43.2% - 74.4% dan -55.1% - 42.7%. Perlakuan ekstrak kasar menunjukkan lebih efektif dalam menekan BCMV dibandingkan perlakuan ekstrak protein. Diantara ekstrak kasar yang diuji, ekstrak bogenvil dan jambu biji menunjukkan penekanan BCMV tertinggi di lapangan
Keyword: antivirus, BCMV, plant extract, yard long bean

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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