Judul: Pengaruh Infeksi Squash mosaic comovirus Terhadap Perkembangan Penyakit Mosaik pada Lima Varietas Mentimun (Cucumis sativus L.)
Abstrak: Squash mosaic comovirus (SqMV) is seed borne pathogens that infect many Cucurbitaceae crop, its presence has expanded in Indonesia. This research aims to 1) know the percentage of SqMV carried by seed on five varieties of cucumber are Jupiter, Venus, Japan File, Vario, and Calista, 2) determine the influence SqMV infection on the mosaic disease development, and 3) determine the effect of SqMV infection to the percentage of SqMV carried by the next generation seeds. Five varieties of cucumbers mechanically inoculated with SqMV then observed symptoms, incubation period, and the incidence of disease. Seed borne virus testing performed by the method of growing-on test. Virus detection used indirect ELISA method and DIBA. Based on testing of cucumber leave samples from Situgede, Bogor by using antisera Cucumber mosaic cucumovirus, Squash mosaic comovirus, Zucchini yellow mosaic potyvirus, Watermelon mosaic potyvirus, and Tobacco ring spot potyvirus known that SqMV is the only type of virus found with the highest titer reached 0.8155. Varieties Venus, Jupiter, Calista, and Vario which infected will show varied symptoms that is mosaic of green, yellow green mosaic, leaf bleaching bones, and malformations in fruit. Observations of disease severity and viral titers showed a pattern of mosaic disease development is decreased in the flowering stage and increased in the fruiting stage. In the vegetative stage, viral titers ranged from 1.3845 to 1.5603, viral titers of the flowering stage decreased, ranging from 0.8966 to 1.2780, and viral titers of the fruiting stage increased again, from 0.8849 to 1.4420. The Japan File gives a different response because the decrease in the severity of the disease continues to bear fruit since the flowering stage. Commercial seed (F1) which is widely used by farmers proved to bring SqMV achieve 100% efficiency and variety of Venus which infected by SqMV produce seed offspring (F2) which brings SqMV with efficiency reaches 60.87%.
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Judul: Pengaruh Infeksi Squash mosaic comovirus terhadap Perkembangan Penyakit Mosaik pada Lima Varietas Mentimun (Cucumis sativus L.)
Abstrak: Squash mosaic comovirus (SqMV) adalah patogen tular benih yang banyak menginfeksi tanaman Cucurbitaceae, keberadaannya di Indonesia sudah meluas. Tujuan penelitian adalah 1) mengetahui persentase SqMV terbawa benih pada lima varietas mentimun yaitu Yupiter, Venus, Japan File, Vario, dan Calista; 2) mengetahui pengaruh infeksi SqMV terhadap perkembangan penyakit mosaik; dan 3) mengetahui pengaruh infeksi SqMV terhadap persentase virus terbawa benih generasi selanjutnya. Lima varietas mentimun diinokulasi dengan SqMV secara mekanis kemudian diamati gejala yang muncul, masa inkubasi, dan kejadian penyakit. Pengujian virus terbawa benih dilakukan dengan metode growing-on test. Deteksi virus dilakukan menggunakan metode indirect ELISA dan DIBA. Berdasarkan pengujian sampel daun mentimun yang berasal dari pertanaman mentimun di Situgede, Bogor dengan menggunakan antiserum Cucumber mosaic cucumovirus, Squash mosaic comovirus, Zuchini yellow mosaic potyvirus, Watermelon mosaic potyvirus, dan Tobacco ring spot potyvirus diketahui bahwa SqMV merupakan satu-satunya jenis virus yang ditemukan dengan titer paling tinggi mencapai 0.8155. Tanaman mentimun varietas Venus, Yupiter, Calista, dan Vario yang terinfeksi akan menunjukkan gejala infeksi SqMV yang bervariasi yaitu mosaik hijau, mosaik kuning hijau, pemucatan tulang daun, dan malformasi pada buah. Pengamatan keparahan penyakit dan titer virus menunjukkan pola perkembangan penyakit mosaik yaitu menurun pada fase berbunga dan meningkat lagi pada fase berbuah. Pada fase vegetatif titer virus berkisar dari 1.3845 sampai 1.5603, pada fase berbunga titer virus menurun, berkisar dari 0.8966 sampai 1.2780, dan pada fase berbuah meningkat kembali yaitu dari 0.8849 sampai 1.4420. Tanaman mentimun varietas Japan File memberikan respons yang berbeda karena penurunan keparahan penyakit berlanjut sejak fase generatif hingga berbuah. Benih komersial (F1) yang banyak digunakan petani terbukti membawa SqMV dengan efisiensi mencapai 100% dan tanaman varietas Venus yang terinfeksi SqMV menghasilkan benih keturunan (F2) yang membawa SqMV dengan efisiensi mencapai 60.87%.
Keyword: cucumber, SqMV, Mosaic

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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