Judul: Diversity of Insect Species at Different Ages of Rhizophora mucronata Stands Grown With Guludan Technique in Muara Angke, Jakarta
Abstrak: Serangga merupakan salah satu makhluk hidup dengan jumlah terbesar di dunia yang memiliki sejumlah manfaat. Namun, masih banyak serangga yang belum teridentifikasi contohnya serangga pada ekosistem mangrove. Setiap umur tegakan memiliki perbedaan struktur vegetasi, sehingga penelitian keanekaragaman serangga pada setiap perbedaan umur R. mucronata penting dilakukan. Pengambilan sampel dilakukan secara purposive sampling dengan mengambil tiga sampel guludan yang berukuran 5 m  10 m. Pada masing-masing sampel dilakukan sensus untuk mengukur diameter dan tinggi R. mucronata pada umur 17, 13, 9, 4 tahun untuk selanjutnya dilakukan analisis vegetasi. Penangkapan serangga dilakukan dengan menggunakan yellow-pan trap lalu diidentifikasi sampai tingkat morfospesies. Hasil menunjukkan terdapat hubungan antara umur tegakan yang berbeda terhadap keanekaragaman dan kelimpahan serangga. Umur muda memiliki kelimpahan dan keanekaragaman serangga lebih tinggi dibandingkan umur tua dan umur R. mucronata 13 tahun memiliki kelimpahan tertinggi yang didominasi oleh ordo Diptera., Insects are among the most significant numbers of living things in the world that have many benefits. However, there are still many insects that have not been identified yet, for example, insects in mangrove ecosystems. Each age of the stand has differences in vegetation structure, so insect diversity research on each age difference of R. mucronata is essential. Sampling was collected by purposive sampling by taking three guludan samples measuring 5 m  10 m. In each sample, a census was carried out to measure the diameter and height of R. mucronata at the age of 17, 13, 9, and 4 years for further vegetation analysis. The capture of insects is carried out using a yellow-pan trap and then identified to the level of morphospecies. The results showed a relationship between the age of different stands. At a young age had a lot of diversity and the highest value of insect abundance. The age of R. mucronata 13 years had the highest quantity dominated by the order Diptera.
Keyword: ekosistem, kerapatan, morfospesies, suhu, yellow-pan trap

Judul: Keanekaragaman Serangga di Ekosistem Mangrove: Studi Kasus Hutan Mangrove di Kawasan Pesisir Angke Kapuk, Jakarta Utara
Abstrak: Mangrove is the habitat of various insects which have important function of ecosystem. However, many insect species and their functions in mangrove ecosystem have not been identified yet. This research is aimed to elucidate the species composition of mangrove in relation to the species diversity of insect. This research was conducted in three different mangrove stand in Mangrove Protection Forest of Angke Kapuk and Soedyatmo highway mangrove area. They are monoculture stand of A. marina, mixed stand of A. Marina and R. mucronata, and mixed stand of S. alba and R. mucronata. Sampling was collected by using line quadrat method. There were eight quadrats (10 m × 10 m) suspended at every mangrove stand. Incest traping was using yellow-pan trap method. The result indicates that the mixed stand A. Marina and R. mucronata has the highest value of insects abundance. The dominant insect at every mangrove stand were order of Diptera.
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: