Judul: Ethnobotany Sago (Metroxylon sagu Rottb) Mentawai  people in Siberut National Park, Mentawai Islands Regency
Abstrak: Studi etnobotani merupakan ilmu yang mempelajari pengetahuan masyarakat secara tradisional terhadap keanekaragaman tumbuhan di sekitarnya serta pemanfaatan tumbuhan tersebut. Masyarakat Mentawai memanfaatkan tumbuhan sagu sebagai pangan pokok sejak nenek moyang mereka, baik untuk makanan pokok, atap rumah dan perkawinan adat. Tujuan penelitian untuk mengetahui etnobotani sagu (Metroxylon sagu Rottb), perbandingan bentuk pemanfaatan dari beberapa masyarakat dan hambatan, upaya konservasi serta rencana pengembangan sagu secara berkelanjutan oleh Masyarakat Mentawai di Taman Nasional Siberut, Kabupaten Kepulauan Mentawai. Metode pengambilan data menggunakan teknik snowball sampling. Pemanfaatan sagu oleh Masyarakat Mentawai terdiri atas daun, kulit pelepah, kulit batang, batang (empulur) dan akar. Masyarakat belum memanfaatkan sagu secara optimal serta upaya konservasi yang dilakukan agar kelestarian sagu terjaga, perlu adanya perhatian khusus dari pihak pemerintah daerah perihal fasilitas pendukung, edukasi dan pendampingan budidaya sagu., The study of ethnobotany is a science that studies traditional community knowledge of the diversity of plants in the vicinity and the use of these plants. The Mentawai people use sago plants as staple food since their ancestors, both for staple food, roofs and traditional marriages. The purpose of this study was to determine the ethnobotany of sago (Metroxylon sago Rottb), comparison of forms of use from several communities and obstacles, conservation efforts and sustainable development plans of sago by the Mentawai Community in Siberut National Park, Mentawai Islands Regency. The data collection method used snowball sampling technique. The use of sago by the Mentawai community consists of leaves, midrib bark, bark, stem (pith) and roots. The community has not utilized sago optimally and the conservation efforts that have been made to maintain the sustainability of sago, need attention from the local government for special support, education and assistance in sago cultivation.
Keyword: ethnobotany, Metroxylon sago, snowball, conservation efforts

Judul: Medicinal Plants Diversity on Sago Stands in Siberut National Park, West Sumatera
Abstrak: Tumbuhan obat dapat ditemukan pada berbagai tipe habitat termasuk tegakan sagu yang banyak dijumpai di Taman Nasional Siberut. Tujuan dari penelitian ini yaitu mengidentifikasi, mendeskripsikan dan menganalisis keanekaragaman spesies tumbuhan, bentuk pemanfaatan tumbuhan obat oleh masyarakat adat Mentawai, ketersediaan tumbuhan obat dan potensi pemanfaatan tumbuhan obat pada tegakan sagu di Taman Nasional Siberut. Kegiatan penelitian dilaksanakan pada Januari‒Maret 2022 di Dusun Sakaladhat, Desa Simalegi, Kecamatan Siberut Barat dan Dusun Ukra, Desa Malancan, Kecamatan Siberut Utara dengan metode analisis vegetasi, wawancara dan observasi lapang. Terdapat 193 spesies tumbuhan dari 64 famili pada tegakan sagu. Sebanyak 60 spesies dari 31 famili telah dimanfaatkan masyarakat sebagai bahan obat sementara 55 spesies dari 36 famili berpotensi untuk dimanfaatkan sebagai bahan obat. Pemanfaatan tumbuhan obat oleh sikerei dan siagai laggek yang merupakan dukun atau ahli pengobatan di Dusun Sakaladhat dilakukan sesuai dengan pengetahuan yang diperoleh dari mimpi sementara itu pemanfaatan di Dusun Ukra disesuaikan dengan keahlian masing-masing yang diperoleh dari mimpi dan warisan turun-temurun. Ketersediaan tumbuhan obat pada tegakan sagu dapat mencukupi kebutuhan untuk mengobati 36 jenis penyakit yang diderita oleh masyarakat untuk jangka waktu 1 tahun. Penelitian ini diharapkan dapat memberikan sumbangan pengetahuan mengenai pemanfaatan tumbuhan obat pada tegakan sagu oleh masyarakat tradisional., Medicinal plants exist at various habitats including sago stands in Siberut National Park (SNP). This study aims to identify, describe, and analyze of species diversity, utilization types, availability and latent utility of medicinal plants on sago stands by Mentawai community in SNP. This research was conducted in January-March 2022 at Sakaladhat Hamlet, Simalegi Village and Ukra Hamlet, Malancan Village by carrying out vegetation analysis, interview and observation. Results show that 193 species from 64 families were found on sago stands. People have availed of 60 species from 31 families as temporary medicine while other 55 species from 36 families have potential use as remedy. Medicinal plants usage by sikerei and siagai laggek as local physicians in Sakaladhat gained purely from their spiritual dreams. Meantime, different approach of those physicians in Ukra corresponds with each ability from spiritual dreams and local knowledges passed through generations. This research reveals that these medicinal plants are sufficient enough to cure 36 illnesses for a year long. This research, in turn, may contribute to better understanding on sago’s stands medicinal plants utility by local community.
Keyword: diversity, local knowledge, medicinal plant, sago stands

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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