Judul: Komposisi Mikroorganisme Penyusun dan Kandungan Nutrisi Bioflok dalam Media Pemeliharaan Induk Ikan Nila Oreochromis niloticus dengan Aplikasi Teknologi Bioflok
Abstrak: This study aims to analyze the composition of microorganisms and primary nutrients in biofloc collected from tilapia Oreochromis niloticus broodstock tanks cultured with the application biofloc technology. Samples were taken from 8 biofloc bath unit tilapia maintained for 3 months with two different treatments ie control treatment (without the addition of molasses) and bioflok (with the addition of molasses). The results showed that the abundance of bacteria and plankton in biofloc treatment tends to increase with the maintenance period. The results of the identification of bacterial isolates found in water conservancy media obtained 7 types of bacteria in biofloc system are Actinobacter sp., Listeria sp., Kurthia sp., Actinobacillus sp., Streptococcus sp., Bacillus sp., Micrococcus sp. and 5 types of bacteria in the control Actinobacter sp., Listeria sp., Kurthia sp., Actinobacillus sp., Streptococcus sp.. Types of phytoplankton that dominate biofloc treatment at the end of the study were a group of Chlorophyceae genus Scenedesmus as many as 1,936,804 cells/L. While in the control Cyanophyceae dominated by genus of Microcystis much as 4,967,296 cells/L. Contain of biofloc nutrition were 37.37 % protein, 1.66% of lipid, 2.05% of crude fiber, and 2.26% of ash.
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Judul: Feed Utilization and Growth Performance of Nile Tilapia (Oreochromis niloticus) in Different Biofloc System
Abstrak: Biofloc accumulation in rearing media could disturb the feed utilization by the cultured fish. One of the solutions to solve the problems is by using settling tank. This study aimed to compare feed utilization and growth performance of nile tilapia in biofloc system with settling tank and without settling tank. This study use two treatments, i.e. biofloc system with settling tank (Bioras) and biofloc system without settling tank (Control) with three replication for each treatment. Fish was reared in outdoor tarpaulin tanks with a diameter of 3 m and a height of 1,2 m, which was filled with about 5000 L of water. Tilapia with an initial average weight of 100 g was cultured at initial density 5 kg m-3 for 112 days with a partial harvest at day-29. Tilapia was feed with comercial diets (protein content 30,54% and lipid content 4,37%) twice a day to apparent satiation. The result showed that feed utilization and growth perfomance of nile tilapia in bioras is better than control. In conclucion, the addition of settling tank in biofloc system make a better impact in feed utilization and growth performance of nile tilapia (Oreochromis niloticus). Keyword : biofloc, bioras, settling tank, tilapia, Akumulasi bioflok dalam media pemeliharaan dapat mengganggu kemampuan ikan dalam memanfaatkan pakan. Salah satu solusi untuk menangani masalah tersebut adalah dengan penggunaan bak pengendapan. Penelitian ini bertujuan untuk membandingkan tingkat pemanfaatan pakan dan kinerja pertumbuhan ikan nila pada sistem bioflok dengan bak pengendapan dan tanpa bak pengendapan. Penelitian ini menggunakan dua perlakuan, yaitu bak pemeliharaan ikan dengan media bioflok dengan penggunaan bak pengendapan (Bioras) dan bak pemeliharaan ikan dengan media bioflok tanpa penggunaan bak pengendapan (Kontrol) dengan tiga ulangan. Pemeliharaan ikan dilakukan di ruang terbuka (outdoor) menggunakan bak terpal dengan diameter 3 m dan tinggi 1,2 m yang diisi air sebanyak 5000 L. Ikan nila dengan bobot rata-rata awal 100 g dipelihara dengan kepadatan 50 ekor m-3 selama 112 hari dan dilakukan panen parsial pada hari ke-29. Ikan nila diberi pakan dengan pelet komersil (kadar protein 30,54% dan lemak 4,37%) dua kali sehari secara at satiation. Hasil penelitian ini menunjukkan bahwa kinerja pertumbuhan dan pemanfaatan pakan ikan nila pada sistem bioras lebih baik daripada kontrol. Berdasarkan hasil penelitian ini dapat disimpulkan bahwa penambahan bak pengendapan pada sistem bioflok memberikan dampak yang lebih baik pada kinerja pertumbuhan dan pemanfaatan pakan ikan nila merah (Oreochromis niloticus).
Keyword: biofloc, bioras, settling tank, tilapia

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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