Judul: Oligochaeta Cultivation with Different Stocking Densities at opened system.
Abstrak: Cacing oligochaeta atau yang lebih dikenal dengan cacing sutra merupakan salah satu jenis pakan alami yang memiliki kandungan nutrisi cukup tinggi dan banyak dicari para pembudidaya benih ikan. Penelitian ini bertujuan untuk menentukan puncak populasi dan biomassa tertinggi serta padat penebaran efektif dalam usaha budidaya cacing oligochaeta sistem terbuka, yaitu dengan pengaliran dan penggantian air setiap saat. Wadah yang digunakan berupa kotak kayu berukuran (100x25x20) cm3 yang dilapisi plastik hitam. Media yang digunakan yaitu campuran lumpur dan kotoran ayam. Perlakuan padat penebaran yang diujikan adalah 2600 individu/m2, 3600 individu/m2, dan 4600 individu/m2. Masing-masing perlakuan diulang sebanyak 3 kali. Cacing oligochaeta diberi pupuk tambahan berupa kotoran ayam hasil fermentasi sebanyak 1 kg/m2 setiap hari. Hasil penelitian menunjukkan puncak populasi dan biomassa cacing oligochaeta terjadi pada hari ke-40. Populasi tertinggi didapat pada perlakuan padat penebaran 4600 individu/m2 yaitu 447.904 individu/m2 dengan biomassa 2.239,52 g/m2, dan laju pertumbuhan biomassa sebesar 55,41 g/m2/hari (p<0.05). Kualitas air selama penelitian masih dalam kisaran optimum bagi pertumbuhan cacing oligochaeta. Perlakuan padat penebaran 4600 individu/m2 paling efektif untuk kegiatan usaha budidaya cacing oligochaeta dengan asumsi menggunakan 200 unit produksi dan harga jual cacing oligochaeta yaitu Rp 100.000 per kg, memberikan keuntungan sebesar Rp 52.892.500; R/C ratio sebesar 2,44; nilai BEPp yaitu Rp 28.429.146; BEPu yaitu 284,29 kg, HPP sebesar Rp 40.956 per kg; dan payback period selama 0,27 tahun atau 3,24 bulan.
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Judul: Budidaya Cacing Oligochaeta dengan Padat Penebaran Berbeda pada Sistem Sirkulasi dengan Pergantian Air
Abstrak: Oligochaeta worm contain protein of 65%, fat 15%, and carbohydrate 14%, therefore very well when given to the fish larvae during nursery period. But, the availability of oligochaeta worm are very limited especially in Belitung which has 10 hatchery. So that, it needs oligocheta worm cultivation to meet the demand. The research used closed system which mean wasted water from. The purpose of this research to determine the best stocking denstiy of oligochaeta worm between 2600,3600, and 4600 indvidual/m2 with the system based on the biomass, growth rate,and economic efficiency. The research was perfomed in April until August 2011 at the Balai Benih Ikan Air Tawar Belitung Timur. The medium used are a mixture of fine mud and chicken manure. The worm was spread and fermentation manure chicken fertilized added every day about 1 kg/m2. The worm was cultured during 60 days and took as samples every 10 days. The observation indicated that the maintanence of oligocaeta worm with closed system produced the level of ammonia contain was higher and dissolve oxygen contai was lower than using opened system. In this condition, the worm was able to survived even thought feeding habit and reproduction is inhibited. Highest population and biomass occured on 50th day with stocking density 4600 individual/m2 as much as 255091.61 individual/m2 and 1275.46 g/m2. Highest biomass growth rate occured in 4600 individual/m2 as much as 25.05 g/m2/day. Stocking density 4600 individual/m2 got the profit as much as Rp 5 828 525, R/C ratio 1.04, PP for 6.13 years, BEP (Rupiah) Rp 154 585 260 and BEP (units) 937 kg, and HPP Rp 72 389.
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Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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