Judul: Keanekaragaman dan Kelimpahan Arthropoda pada Perkebunan Teh 600-900 meter dari Tepi Hutan di Kebun PTPN VIII Gunung Mas, Bogor, Jawa Barat
Abstrak: Tea (Camellia sinensis) is one of the plantation commodities that have a strategic role for the Indonesian economy. Almost of every year tea production has decreased, this is due to pest attack. Pest is one part of Arthropoda herbivore. Diversity and abundance Arthopoda in tea gardens need to know because some Arthropods have a beneficial role. The experiment was conducted to identify the diversity and abundance Arthropoda at tea plantation PTPN VIII Gunung Mas,. The research used three sampling methods, that is: net insect, Branches beating and pitfall trap. Identification of Arthropods in the Laboratory Bioecology Insects, Department of Plant Protection, Faculty of Agriculture, Bogor Agricultural University. Diversity Arthropoda 600 meter to 700 meters from forest edge has highest number is 49 family. The Arthropod proportions as predator is 46%, parasitoid 6%, herbivor 41% and detrivor 7%. Tea plants are generally much damage caused by Helopeltis sp. and Hyposidra talaca. Arthropod predators, parasitoids and herbivors most commonly found with nets and detrivor is most widely with pitfall trap method.
Keyword: 

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%.
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: