Judul: Keanekaragaman simplisia nabati dan produk obat tradisional di Kota Pematangsiantar dan Kabupaten Simalungun, Sumatera Utara
Abstrak: The utilization of medical plants as traditional medicine is a great inherintance which has been used until present. Medicinal plants used in the form of vegetable simplisia and traditional medicine products. This study aims to identified the form an diversity of vegetable simplisia and traditional medicine product, traditional medicine products traded, the selling price and origin of the traded vegetable simplisia supply and the potential for sustainable management of medicinal plants as vegetable simplisia. Data and information are collected in Pematangsiantar and Simalungun, North Sumatera using direct observation and interviews with purposive sampling. The results show that 113 species of medicinal plants come from 46 families that dominated by Zingiberaceae. Vegetable simplisia dominated by herb life form and simplisia leaf (folium) are organ of the most used medicinal plants as medicine by local communities and the traders medicinal plants. The majority of medicinal plants traded and local communities utilized are cultivated plants which selling price around Rp 16 000-Rp 700 000 each kilogram. There were included 22 spesies medicinal plants of threatened category according to IUCN, CITES LIPI, and Permen LHK No. P.106 Year 2018.
Keyword: Pematangsiantar, Simalungun, traditional medicine, vegetable simplisia

Judul: Keanekaragaman Simplisia Nabati dan Produk Obat Tradisional di Kota Pematangsiantar dan Kabupaten Simalungun, Sumatera Utara
Abstrak: Pemanfaatan tumbuhan sebagai obat tradisional merupakan warisan yang masih digunakan hingga saat ini. Tumbuhan obat yang digunakan berupa simplisia nabati dan produk obat tradisional. Tujuan penelitian ini adalah mengidentifikasi bentuk dan keanekaragaman simplisia nabati, mengidentifikasi produk obat tradisional yang diperdagangkan dan mengidentifikasi potensi pengelolaan lestari tumbuhan obat sebagai simplisia nabati di Kota Pematangsiantar dan Kabupaten Simalungun, Sumatera Utara. Pengumpulan data dilakukan pada bulan Mei-Juli 2017 dengan cara observasi langsung dan wawancara. Simplisia nabati yang diperdagangkan di di Kota Pematangsiantar dan Kabupaten Simalungun sebanyak 11 bentuk simplisia nabati dengan 113 spesies tumbuhan obat yang berasal dari 46 famili dan didominasi famili Zingiberaceae. Simplisia nabati yang diperdagangkan didominasi oleh habitus herba dan bagian tumbuhan yang paling banyak digunakan adalah daun (folium). Simplisia nabati yang diperdagangkan umumnya berasal dari budidaya dengan harga jual antara Rp 16 000-Rp 700 000 per kilogram. Sebanyak 22 spesies tumbuhan obat termasuk dalam status keterancaman menurut IUCN, CITES LIPI dan Permen LHK No. P.106 Tahun 2018.
Keyword: obat tradisional, Pematangsiantar, Simalungun, simplisia nabati

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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