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 yang Diperdagangkan di Kota Padang, Sumatera Barat
Abstrak: The utilization of plants as traditional medicine has been known from generation to generation and continued to grow up until now. Nowadays, medicinal plants are often used in the form of simplisia. Simplisia was natural material which have not undergone a change of form and can be used as medicine. The aim of this research was to identified kinds of simplisia vegetable, traditional medicinal products, the origin of supply and also the simplisia’s price that had been traded in Padang City. Data collection was done by direct observation and interview method. The result showed that there are 142 medicinal plant species from 56 families which is traded as simplisia. Most medicinal plants sold in the form of simplisia were obtained from plants that grows wild in the nature and also from cultivation. Simplisia from the wild have price between Rp2 000 to Rp5 000 / bunch. This price is still too low considering that there are some simplisia from the forest which has been categorized as rare plants, such as pulosari (Alyxia reinwardtii) and pulai (Alstonia scholaris). Traditional medicinal products traded in Padang city were produced by home industries, medium-scale industries, and top-scale industries in Java. There are 53 kinds of traditional medicinal products from 9 traditional medicine industries in Indonesia.
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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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