Judul: Diversity of Forest Floor Vegetation Species in the  Napabalano Nature Reserve and Warangga Protection Forest, Muna Regency,  Southeast Sulawesi Province
Abstrak: Cagar Alam Napabalano dan Hutan Lindung Warangga merupakan kawasan hutan sekunder dataran rendah dengan masing-masing luas hutan 10,5 ha dan 18,2 ha yang berada pada ketinggian kurang dari 100 mdpl. Meskipun ketinggian wilayah Cagar Alam Napabalano dan Hutan Lindung Warangga relatif sama, tetapi karena adanya perbedaan faktor lokasi dimana Cagar Alam Napabalano letaknya berdekatan dengan pantai dan Hutan Lindung Warangga berdekatan dengan sumber air, sehingga hal tersebut diduga menyebabkan perbedaan komposisi dan keragaman vegetasi pada lantai hutannya.Tujuan penelitian ini adalah untuk mengidentifikasi keragaman jenis vegetasi lantai hutan di Cagar Alam Napabalano dan Hutan Lindung Warangga, menganalisis perbedaan komposisi jenis dan keragaman jenis vegetasi lantai hutan, serta menganalisis faktor lingkungan yang mempengaruhi perbedaan komposisi dan keragaman jenis vegetasi lantai hutan di Cagar Alam Napabalano dan Hutan Lindung Warangga. Penelitian ini telah dilaksanakan pada bulan November 2020 hingga Maret 2021 di Cagar Alam Napabalano dan Hutan Lindung Warangga dengan menggunakan teknik analisis vegetasi dengan metode kudarat. Pengambilan sampel sebanyak 15 petak contoh yang terdiri dari plot berukuran 20 m x 20 m, 10 m x 10 m, 5 x 5 m dan 2 x 2 m. Metode pengambilan sampel dilakukan secara purposive sampling menyesuaikan dengan kondisi lapangan. Dilakukan pengukuran faktor lingkungan meliputi suhu, kelembapan udara, kelembapan tanah, pH tanah, presentase penutupan kanopi dan ketebalan serasah. Analisis data lingkungan dari masing-masing petak contoh dianalisis menggunakan Canonical Correspondence Analysis (CCA) dengan program CANOCO. Pengambilan sampel tanah dilakukan di 15 titik pengamatan dan dianalisis faktor fisik dan kimianya. Seluruh jenis tumbuhan diidentifikasi dan dihitung jumlahnya dan dianalisis untuk mendapatkan Indeks Nilai Penting (INP), Indeks Keragaman Jenis (H’), Indeks Kemerataan Jenis (E), Indeks Dominansi (C) dan Indeks Kesamaan Komunitas (Is). Spesies penyusun vegetasi dominan di Cagar Alam Napabalano yaitu Leea indica dan Ardisia saguinolenta, sedangkan spesies dominan di Hutan Lindung Warangga adalah Chromolaena odorata dan Oplismenus undulatifolius. Komposisi jenis penyusun vegetasi lantai hutan di Cagar Alam Napabalano terdiri dari 41 spesies dengan jumlah famili yang ditemukan sebanyak 33 famili. Adapun komposisi vegetasi lantai hutan pada Cagar Alam Napabalano ini tersusun dari 18 spesies tumbuhan bawah dan 23 spesies merupakan tingkatan pertumbuhan semai. Selain itu, vegetasi lantai hutan yang ditemukan di Hutan Warangga yaitu sebanyak 57 spesies dengan jumlah famili yang dijumpai sebanyak 36 famili. Komposisi vegetasi lantai hutan pada Hutan Lindung Warangga meliputi 35 spesies termasuk tumbuhan bawah dan 22 spesies termasuk tingkat pertumbuhan semai. Analisis CCA menunjukkan bahwa secara umum faktor lingkungan yang cenderung paling memengaruhi keragaman dan komposisi jenis vegetasi lantai hutan di Cagar Alam Napabalano adalah intensitas cahaya, kelembapan udara, pH tanah dan kanopi (naungan), sedangkan di Hutan Lindung Warangga faktor lingkungan yang paling memengaruhi adalah temperatur dan intensitas cahaya, kelembapan udara dan pH tanah. Setiap jenis tumbuhan memiliki tingkat toleransi tertentu terhadap faktor faktor lingkungan yang ada di sekitarnya agar dapat terus tumbuh., The Napabalano Nature Reserve and the Warangga Protection Forest are lowland secondary forest areas with forest areas of 10,5 ha and 18,2 ha, respectively, located at an altitude of fewer than 100 meters above sea level. Although the heights of the Napabalano Nature Reserve and Warangga Protection Forest are relatively the
Keyword: diversity, environmental factors, forest floor vegetation

Judul: Komposisi Jenis dan Struktur Tegakan Hutan di Cagar Alam Sibolangit, Sumatera Utara
Abstrak: Forest is an ecosystem that combines the interaction between biotic and abiotic factors. Ecologically, the formation of forest community formed gradually through the changing of the vegetation and habitat. Community of forest is a dynamic and always changing until it reaches a optimum stage. The growth of a tree species in a forest community is influenced by several factors, including climatic factors, edaphic, physiological and biotic factors. The changing in the factors mentioned previously will take effect on the vegetation structure and composition. Forest with a variety functions and benefits provide a tremendous influence both directly and indirectly to several aspects such as ecology, economic, and social. Utilization of forests can be well manage and reach the sustainably if the information about the forest condition are available. Sibolangit Nature Reserve which is located in Deli Serdang regency. The existence of the Sibolangit Nature Reserve with high biodiversity information still limited, therefore it is necessary needed to have a study of nature reserve in order to explore the benefits and potency of the nature reserve without disturbing the presence and preservation of the forest. Hence, we need a study to in the Nature Reserve Sibolangit of the forest, analyze species the composition, and structure. This research conducted from December 2008 until January 2009 using vegetation analysis techniques with the transeet methods. As preliminary, the transeet divided into plots of 20m x 20m to inventory the trees, 10m x 10m to analyze the pole, 5m x 5m to inventory the saplings, and the 2m x 2m to inventory the seedling. For the sampling unit it uses a sampling design in the form of systematic sampling with random start. Based on the results of observation, the seedlings and saplings dominated by Sono keling (Dalbergia latifolia). While for the poles and trees dominated by Angsana (Pterocarpus indicus). The diversity value in Sibolangit Nature Reserve classified as medium diversity. In Sibolangit Nature Reserve, the highest Similarity Index values was found in the north-south slope and the lowest one found in north-eastern slopes. Forest vegetation Sibolangit Nature Reserve in vertical point of view consists of three strata, namely the stratum A (tree height over 30 meters), stratum B (tree 20-30 meters high), and stratum C (tree height 4- 20 meters), where most of the tree population is distributed in the canopy stratum from 11 until 20 meters. All individuals in the forest show clustered distributed at both the tree and forest regeneration level.
Keyword: 

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model