Judul: Pengaruh Kondisi Lahan Pertanian terhadap Kelimpahan Serangga Penyerbuk: Implikasi terhadap Produksi Mentimun
Abstrak: Insect pollinators play an important role in pollination on various plants, including cucumber. This research aims to study the influence of natural habitat toward the abundance of insect pollinator and its effect on cucumber production. This research was conducted at six locations with various distances to natural habitat. Three locations were categorized as locations near natural habitat, i.e. less than 200 m. The other three locations were categorized as locations far from natural habitats, i.e. 1000 m. The observations of insect pollinator abundance were conducted by counting the number of insect pollinator that perched on 100 units flower in four different spots. The observations were conducted at four different times. Several variables were observed, i.e. the weight of cucumber, amount of seeds, dried weight of seeds, length and width of cucumber, on four different subplots sized 1 m x 1 m. The results showed that the presence of natural and seminatural habitats surrounding agricultural land, influence the abundance of insect pollinators. Whereas time of the highest numbers of insects pollinating the flower were at 9 am, 11 am and 3 pm. There is no correlation between the numbers of individuals with cucumber production.
Keyword: natural habitat., insect pollinator, cucumber production, abundance

Judul: Keanekaragaman Serangga Penyerbuk pada Pertanaman  Mentimun Pengaruh Keberadaan Habitat Alami
Abstrak: Pollination is a critical first step in sexual reproduction of flowering plants. Insect pollinator plays an important role in pollination prosess of flowering plants, including cucumber. The aims of this study are to determine the influence of natural habitats toward the diversity insect pollinators and to gain informations of the relationship between insect pollinator diversity and the number of flowers. The research was set up in six locations with different distances from the natural habitat. Three locations are categorized as being in a close proximity to natural habitat (D), which is about ≤200 m and three other locations are categorized as far from natural habitats (J), with a distance of ≥1000 m.The distance between the locations are 1.5 km. Observations were conducted by two methods, sweeping net and malaise traps. Number of flowers were counted using the amount of flower activities which open and close at four points for each by 1 m x 1 m plot. Results showed that agricultural land conditions affect the abundance of insect pollinators. The highest diversity of insects were found in the morning, e.g.- at 09:00 am and 11:00 am. No correlation were found between the numbers of species of insect pollinators and the numbers of flower.
Keyword: pollination., natural habitat, insect pollinator, 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.
Keyword: