Judul: Diversitas Semut pada Tumbuhan Sonneratia caseolaris (L.)Engl. di Suaka Margasatwa Muara Angke
Abstrak: Mangrove is a dynamic group of trees with high productivity, which plays a major role in food chain. Ants (Formicidae) are the most abundant insect in the world. Higher biomass and abundance of ant in the tropical rainforest canopy are the reason why the ecological study of ants diversity become essential. Sonneratia caseolaris is a dominant tree species in Muara Angke Nature Reserve (MANR). Study of abundance and composition of ants were needed to indicate stability of this reserve. The research aim to study the diversity of ants and its contribution on S. caseolaris in MANR. The research was conducted from April-June 2012. Observation of ants were conducted in observation track in MANR and were made 8 points for collecting the ants. Collection of ants were conducted using 2 methods, beating sheet and pitfall trap. Result showed that 12 genera from 6 subfamilies and total of 2.280 individuals of ants were found. Camponotus, Oecophylla, and Polyrhachis were dominant genera found in MANR. Shannon-Wiener and Evennens Index value of ants were 0,9 and 0,33 respectively. Beating sheet cought more individual of ants than pitfall trap. We found predatory ants which potentially protect of S. caseolaris from its herbivore
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Judul: Keanekaragaman Semut pada Berbagai Tipe Penggunaan Lahan di Jambi
Abstrak: Conversion of tropical forests, mainly to agricultural area is the most important driver of tropical biodiversity loss. As dominant species in lowland forests, ant species diversity is prone to decline sharply due to forest transformation. This research was conducted to investigate the diversity of ants and its role in different land use. Ecological research was conducted in four types of land-use i.e. forest, jungle rubber, oil palm plantation and rubber plantation, located within two landscapes i.e. Bukit Duabelas National Park and Harapan Forest in Jambi, Indonesia. Each type of land use, four plots were selected for ant sampling. Ants were collected using baiting methods, combination between tuna and sugar. Ant diversity in Harapan Forest higher than in TNBD. In total, 66 species of ants belonging to 4 subfamilies and 20 genera were recorded from both area of Bukit Duabelas and Harapan. Surprisingly, the highest number of ant species was found in oil palm plantation. In addition, the compositions of ants based on its role showed differ among land-use types. It indicates that land-use change drive ant species composition.
Keyword: land use, foresty, ant diversity

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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