Judul: Fenologi Pembungaan Pinang Yaki (Areca vestiaria Giseke) di Kebun Raya Bogor
Abstrak: One of the palm genus that available widely in Indonesia is Areca. Areca vestiaria is a palm species endemic in Sulawesi which has an unique characteristics and important components in a tropical rainforest. A. vestiaria has many functions, such as, materials for handicrafts, medicinal herb of diabetes, and for male tonic. Based on the benefits, people will continue to use it. Uncontrolled utilization will lead it to extinction. Hence, need of conservation to preserve it. For this reason, it is necessary assess aspects of flowering phenology of A. vestiaria. Samples consist of lowland and upland Sulawesi accessions. Parameter of flower phenology consist of period of development flowering time, at each development phase, and the micro-climate factors. Flowering of A. vestiaria includes of initiation, bud towards anthesis, anthesis, and young fruit until maturity. The result showed that in each phase has a different time. Overall, the flowering development was not directly affected by a particular micro-climate factors. The insects visitors dominant were Trigona sp. and windspeed was caused high persentage of pollination.
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Judul: Fenologi Pembungaan Pinanga (Palmae) di Kebun Raya Bogor
Abstrak: Pinanga (Palmae) memiliki keragaman jenis yang besar dan tersebar dari Himalaya dan China Selatan hingga Papua New Guinea. Pinanga memiliki beberapa kegunaan yaitu sebagai tanaman hias, obat, dan lain-lain. Penelitian ini bertujuan untuk mendeskripsikan fenologi pembungaan dan serangga pengunjung pada P. coronata, P. celebica, dan P. insignis. Penelitian menggunakan metode deskriptif yang meliputi waktu, tahapan perbungaan, ciri morfologi, faktor lingkungan yang mempengaruhi dan serangga pengunjung. Tahapan perbungaan Pinanga meliputi inisiasi, kuncup menuju antesis, antesis dan penyerbukan. Pada Fase inisiasi terjadi pertambahan ukuran pelepah, daun berwarna kuning dan layu. Fase kuncup menuju antesis ditandai dengan seludang sudah terlihat dan terjadi perubahan kemiringan sudut antara seludang terhadap batang. Fase antesis ditandai dengan terjadinya pemekaran sempurna dari kuncup bunga saat petal membuka sempurna. Fase penyerbukan ditandai dengan bunga jantan sudah mulai rontok dan adanya serangga pengunjung. Pinanga coronata memiliki fase perbungaan paling lama diikuti oleh P. celebica kemudian P. insignis. Lama fase perbungaan dipengaruhi oleh kelembapan, intensitas cahaya, angin dan temperatur lingkungan. Serangga pengunjung yang dominan adalah Trigona sp. Serangga ini paling banyak berkunjung pada jam 09.00-10.00 WIB. Pinanga coronata memiliki rata-rata keberhasilan penyerbukan 91.4%, P. celebica memiliki ratarata keberhasilan penyerbukan 52.5%, P. insignis memiliki keberhasilan penyerbukan 88.95%
Keyword: P. coronata, P. celebica, P. insignis, Bogor Botanic Gardens, P. insiguit

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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