Judul: Diversity and Use of Plants in Kelekak in Namang Village, Central Bangka
Abstrak: Kelekak merupakan kearifan lokal yang telah lama dikembangkan oleh masyarakat di Kepulauan Bangka Belitung. Kelekak merupakan suatu kebun campuran (agroforestri) yang terdiri atas beragam pohon penghasil buah dan kayu. Pengetahuan masyarakat Desa Namang dalam pemanfaatan tumbuhan penting dikaji dan didokumentasikan agar pemanfaatan tersebut dapat berkelanjutan serta meningkatkan kesejahteraan masyarakat. Penelitian bertujuan untuk menginventarisasi keanekaragaman spesies tumbuhan, mengindentifikasi pemanfaatan, bioprospeksi potensi tumbuhan, dan sistem kepemilikan lahan kelekak oleh masyarakat, serta mengidentifikasi upaya konservasi kelekak di Desa Namang. Metode penelitian dilakukan dengan wawancara, analisis vegetasi, observasi lapang, dan studi pustaka. Jumlah spesies tumbuhan di seluruh kelekak diperoleh sebanyak 101 spesies yang berasal dari 45 famili. Pemanfaatan tumbuhan oleh masyarakat Desa Namang dikategorikan menjadi beberapa kategori pemanfaatan dengan pemanfaatan terbanyak yaitu pemanfaatan untuk pangan. Sistem kepemilikan lahan oleh masyarakat sebagian besar merupakan lahan milik pribadi dengan rata-rata luas lahan sebesar 2 hektar., Kelekak is local wisdom that has long been developed by the people of the Bangka Belitung Islands. Kelekak is a mixed garden (agroforestry) consisting of a variety of fruit and wood producing trees. The knowledge of the Namang Village community in the use of plants is important to study and document so that this use can be sustainable and improve community welfare. The research aims to inventory the diversity of plant species, identify utilization, bioprospection of plant potential, and the kelekak land ownership system by the community, as well as identify kelekak conservation efforts in Namang Village. The research method was carried out using interviews, vegetation analysis, field observation, and literature study. The diversity of plant species in each kelekak was found to be 101 species from 45 families. The use of plants by the people of Namang Village is categorized into several categories of use with the largest use being use for food. The community's land ownership system is mostly private land with an average land area of 2 hectares.
Keyword: agroforestry, plants diversity, plants utilization

Judul: Etnobotani dan Potensi Tumbuhan Berguna di Kampung : Keay, Kabupaten Kutai Barat, Kalimantan Timur.
Abstrak: Keay Village is one of villages in West Kutai Regency, East Kalimantan. There are four ethnic groups occupying this village, i.e. Dayak, Javanese, Toraja, and Bugis. Dayak is the dominant ethnic group occupying the village, which still has traditional wisdom/knowledge in plants use. Ethnobotany is expected to document and hand on the knowledge of Dayak Benuaq ethnic group in using plants, and keep the knowledge from being loss. Data were collected through literature study, interview, field survey and inventory, vegetation analyses, and herbarium collection. Data on plants species found were classified in to classification of use, classification of illnesses, habitués percentage and parts of plants used, important value index, Shannon-Wienner species diversity index, and percentage of useful plants potential. There were 396 plant species found through ethnobotany and vegetation analyses, which was categorized into three categories i.e. plant species found through ethnobotany (285 species), plant species found through vegetation analyses in natural forest (158 species), plant species found through vegetation analyses in hevea plantation (34 species). There were 285 species belong to 78 families which uses had been known and grouped into 16 use groups. There were 53,79% of plants species in natural forest had the potential as useful plants, while in hevea plantation there were 50% of that species had the potential as useful plants. Dominant plant species in natural forest was keranyiq (Fordia johorensis) with IVI (Important Value Index) of pole level as much as 19,69%, sapling (25,46%), and seedling (24,67%). In hevea plantation, dominant plant species was hevea (Hevea brasiliensis) with IVI the highest IVI of tree level as much as 300%, pole (284,63%), sapling (143,59%), and seedling (52,42%). Plants use most widely used for medicinal as much as 95 species of 43 families. The community uses more plants from the forest than from the plantation, because there were more useful plants species in the forest. Potential useful plants at the forest of Keay village included mara uleq (Eurycoma longifolia), uwe (Korthalsia sp., Calamus sp., Daemonorops sp.), empulung (Asplenium nidus), and kerakap (Platycerium bifurcatum). Other potential other than plants potential in the natural forest was hevea (Hevea brasiliensis).
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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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