Judul: Keanekaragaman dan Kelimpahan Arthropoda pada Perkebunan Teh 0-1000 Meter dari Permukiman Warga Di PTPN VIII Kebun Ciater, Subang.
Abstrak: Terdapat berbagai jenis Arthropoda yang berasosiasi dengan tanaman teh. Arthropoda herbivor merupakan arthropoda yang dapat menurunkan produksi teh. Perbedaan kondisi di lapang dapat memengaruhi keanekaragaman, kelimpahan, dan peran Arthropoda pada suatu ekosistem. Penelitian bertujuan mengetahui hubungan jarak kebun dari permukiman warga terhadap keanekaragaman dan kelimpahan Arthropoda beserta proporsi peranannya pada perkebunan teh PTPN VIII Ciater, Subang. Penelitian dilakukan dari bulan Desember 2016 hingga Februari 2017. Lokasi pengambilan sampel di perkebunan teh yang berjarak 0-250 (lokasi A), 250-500 (lokasi B), 500-750 (lokasi C), dan 750-1000 m (lokasi D) dari permukiman warga. Metode pengambilan sampel menggunakan sweep net, branches beating, pitfall trap, dan light trap. Hasil penelitian menunjukkan jumlah Arthropoda yang diperoleh selama pengamatan lapang adalah 10 204 individu yang terdiri dari 5 kelas, 18 ordo, dan 100 famili. Keanekaragaman dan Kelimpahan Arthropoda tertinggi terdapat pada lokasi D (750-1000 m dari permukiman warga). Lokasi A (0-250 m dari permukiman warga) memiliki dominansi terhadap beberapa jenis Arthropoda herbivor. Proporsi peranan Arthropoda herbivor, predator, parasitoid, detrivor, dan lainnya pada pertanaman teh secara berturut-turut adalah 41.96%, 38.49%, 8.79%, 8.06%, dan 0.11%. Penelitian ini menunjukkan bahwa jarak perkebunan teh yang semakin jauh dari permukiman warga memiliki keanekaragaman yang tinggi dan kelimpahan terhadap Arthropoda dominan yang rendah.
Keyword: arthropoda, keanekaragaman, kelimpahan, permukiman warga, teh

Judul: Keanekaragaman dan Kelimpahan Arthropoda pada Perkebunan Teh 0-300 meter dari Tepi Hutan di PTPN VIII Gunung Mas, Kabupaten Bogor
Abstrak: Knowledge of pests and natural enemies diversity and abundance on the tea plantation is the essential considetarion for pest control descision by integrated pest management system. This study, conducted in PTPN VIII Gunung Mas tea plantation during 3 months, considered the effect of forest edge through tea boundaries (0-100, 100-200, 200-300 meters from forest edge) on diversity, abundance and family function proportion of Arthropods by pitfall trap, sweep net and branches beating methods for a week. Totally, the classes of Arthropod are Arachnida (3 orders, 19 families, and 1383 species), Diplopoda (3 orders, 6 families, and 27 species) and Insecta (13 orders, 73 families, and 5048 species). The 0-100 meters tea plantation from forest edge has highest number of Arthropods diversity. The highest number of Arthropods abundance is in 100-200 meters from forest edge. A lot of Arthropods have a role as predator on tea plantation (55.53% from total Arthropods). The proportions of herbivore, detrivore, parasitoid, and other are 21.52%, 20.94%, 1.38%, and 0.63%.
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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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