Judul: Dinamika Daerah Penangkapan Ikan, Kaitannya Dengan Aktivitas Pertambangan Nikel Kabupaten Halmahera Timur
Abstrak: Kabupaten Halmahera Timur merupakan salah satu pusat kawasan pertambangan Nikel (Ni) di Maluku Utara. Pertambangan ini memiliki dampak besar terhadap perubahan kualitas perairan. Tujuan penelitian ini adalah menentukan kualitas perairan kawasan pertambangan, radius berapa jauh daerah penangkapan ikan (DPI) bebas dari pengaruh nikel, dan dinamika DPI pada kawasan pertambangan. Penelitian menunjukkan muatan padatan tersuspensi (MPT) di perairan Halmahera Timur telah memberikan pengaruh bagi kepentingan perikanan. Rata-rata kandungan MPT berada diatas 25 mg/l terkecuali Wasile. Kandungan Ni di perairan diketahui berada dibawah 0.05 mg/l, tetapi telah mendekati nilai ambang batas, dimana Ni telah berdampak terhadap perairan. Perubahan kualitas perairan telah memberi dampak pada terdegradasinya ikan di perairan, dimana ikan yang tertangkap dengan menggunakan alat tangkap bagan memiliki ukuran illegal size (IS) lebih dominan, dimana ikan teri memiliki ukuran IS mencapai 62%, dan cumi-cumi mencapaii IS 67%. Besarnya IS pada ikan teri dan cumi-cumi disebabkan oleh pengoperasian bagan yang berada dekat dengan kawasan pesisir dimana, daerah ini telah mengalami tekanan oleh aktivitas pertambangan. Purse seine dan gillnet berada sebaliknya dimana ukuran legal size (LS) lebih dominan. Ikan layang memiliki ukuran LS 96% dan ikan kembung memiliki ukuran LS 90%. Tingginya ukuran LS disebabkan alat tangkap tersebut melakukan penangkapan jauh dari daerah pantai. Nilai variabelitas klorofil-a di perairan Halmahera Timur berada diatas 15%. Keadaan ini menunjukkan sebaran klorofil-a dipengaruhi oleh kekeruhan perairan. Selain menyebabkan penurunan ukuran tangkapan dan kepadatan klorofil-a di perairan pertambangan menyebabkan kerusakan daerah penangkapan ikan dimana DPI yang berjarak kurang dari 1 mil tidak potensial bagi perikanan tangkap.
Keyword: klorofil-a, muatan padatan tersuspensi, nikel, dan panjang pertama kali matang gonad

Judul: Dampak Pertambangan Nikel Terhadap Sosial – Ekonomi – Ekologi Masyarakat di Kecamatan Wasile Kabupaten Halmahera Timur
Abstrak: Wasile, one of the East Halmahera district contained nickel mining, and a great influence on the social, economic and environmental life of the community. Thus this study refers to the theory and previous studies, researchers tried to base it on a frame of mind that the Sustainability of social, economic society strongly influenced by; carrying capacity of the environment, natural resources, human resources, facilities and infrastructure, the financial, social and cultural rights. The purpose of this study was to analyze the impact of nickel mining on socio - economic - ecological communities in the sub District Wasile, East Halmahera. The research center is a sample of 2 (two) villages that are near and far away from the mining of nickel, the village of Batu Raja (near the village) and Subaim Desa (village far). By sampling in this study consisted of local people to be around and who are far away from the nickel mining company, yet to feel the impact of the mining question. The number of samples taken from the respondents ie 80 people consisting of 40 people from each village who are near and far away from the mine site consisting of local people actively working. Direct Observation Field Interviews In-depth interviews using questionnaires Change in Productivity analysis or can be referred to as the Productivity method, Chi-square analysis, and SWOT. Based on the results of mining in the region contribute to the local economy are significant in terms of: (a) regional Revenue, (b) Expansion of employment opportunities, (c) Reduction of unemployment in the area. But the social and ecological impact is not profitable to society. The formulation of the proposed policy are: (1) there was no issuance of new licenses. The hold and maintain the position of the SWOT analysis, meaning that the company's existing nickel can be allowed to continue operations, but the company must pay attention to social and ecological impacts that adversely affect local communities and the environment. Suggestions policies proposed by this research is to increase CSR schemes to improve the adverse effects of mining companies operating in the fields of social and ecological.
Keyword: 

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology