Judul: Kinerja Produksi Pendederan Udang Vaname (Litopenaeus vannamei) dalam Sistem Resirkulasi dengan kombinasi Zeolit dan Bioball
Abstrak: Pendederan udang vaname dengan sistem resirkulasi menjadi salah satu alternatif yang dapat diterapkan untuk meningkatkan produksi, sehingga budidaya dapat dilakukan baik di daerah dekat pantai hingga pekarangan rumah. Media filter pada sistem resirkulasi sangat mempengaruhi kualitas air, biaya produksi, serta keberhasilan budidaya. Penelitian ini bertujuan untuk mengetahui peran kombinasi zeolit dan bioball sebagai filter dalam sistem resirkulasi terhadap kinerja produksi pendederan udang vaname (Litopenaeus vannamei). Desain penelitian yang digunakan adalah rancangan acak lengkap (RAL) yang terdiri dari 4 perlakuan dan 3 ulangan. Perlakuan tersebut terdiri dari 100% zeolit, 75% zeolit dan 25% bioball, 25% zeolit dan 75% bioball, dan 100% bioball. Udang dengan bobot awal 0,004±0,000 g dipelihara dalam akuarium 60 x 40 x 40 cm dengan kepadatan 100 ekor akuarium-1 selama 28 hari dan diberi pakan komersil (protein 41%) sebanyak empat kali sehari dengan feeding rate 8,5–9,0%. Kombinasi 75% zeolit dan 25% bioball (p<0,05) memberikan kinerja produksi terbaik dengan kelangsungan hidup 86,67±1,53%, pertumbuhan bobot spesifik 8,88±0,02%, rasio konversi pakan 1,17±0,06 dan produktivitas 0,66±0,01 kg m-2., Intermediate rearing of vannamei shrimp with a recirculation system is an alternative that can be applied to increase production, so that shrimp farming be carried out both in areas near the coast and in the yard. Filter media in the recirculation system greatly affects water quality, cost production, and the success of farming.This research aims to determine the role of the zeolite and bioball combination as a filter in the recirculation system on the production performance of the vaname shrimp (Litopenaeus vannamei) nursery. The research design used a completely randomized design (CRD) consisting of 4 treatments and 3 replications. The treatments consisted of 100% zeolite, 75% zeolite and 25% bioball, 25% zeolite and 75% bioball, and 100% bioball. Shrimp with initial weights of 0.004±0.000 g are kept in an aquarium 60 x 40 x 40 cm with a density of 100 fish aquarium-1 for 28 days and are given commercial (41% protein) feed 4 times a day with a feeding rate of 8,5–9,0%. The best production performance was obtained in the combination of 75% zeolite and 25% bioball (p<0.05) with 86,67±1,53% survival, growth specific weight was 8,88±0,02%, feed conversion ratio was 1,17±0,06, and productivity was 0,66±0,01 kg m-2.
Keyword: Amonia, bakteri total, nitrat, nitrit

Judul: Effectiveness of using Nitrifying Bacteria Pseudomonas sp. and Denitrifying Bacteria Stenotrophomonas sp. on Culture Media of Vannamei Shrimp Litopenaeus vannamei
Abstrak: Aplikasi bakteri nitrifikasi dan denitrifikasi ke media perairan dilakukan untuk meningkatkan kualitas air budidaya. Penelitian ini bertujuan untuk mengukur efektivitas pengaplikasian bakteri nitrifikasi Pseudomonas sp., denitrifikasi Stenotrophomonas sp., serta perpaduan dari bakteri nitrifikasi dan denitrifikasi dalam mengendalikan lingkungan budidaya udang vaname Litopenaeus vannamei. Hewan uji yang digunakan stadia PL 38 dengan ukuran bobot 2,45±0,23 g dan panjang 7,7±0,25 cm. Bakteri Pseudomonas sp. dan Stenotrophomonas sp. yang digunakan di setiap perlakuan sebanyak 150 mL. Penelitian ini terdiri dari empat perlakuan dengan tiga kali pengulangan. Perlakuan yang diujikan menggunakan kode yang terdiri dari perlakuan K (kontrol), N (aplikasi bakteri Pseudomonas sp. di media air), D (aplikasi bakteri Stenotrophomonas sp. di media air), dan ND (aplikasi bakteri Pseudomonas sp. dan Stenotrophomonas sp. di media air). Penambahan bakteri Pseudomonas sp. dan Stenotrophomonas sp. di media air udang vaname mampu memperbaiki kualitas air, meningkatkan kinerja pertumbuhan, dan mempertahankan kondisi udang vaname dari stres. Hasil penelitian terbaik terdapat pada aplikasi perpaduan bakteri nitrifikasi jenis Pseudomonas sp. dan denitrifikasi jenis Stenotrophomonas sp. di media budidaya udang vaname, The application of nitrifying and denitrifying bacteria to water is carried out to improve the water quality of culture media. This study aimed to measure the effectiveness nitrifying bacteria Pseudomonas sp., denitrifying bacteria Stenotrophomonas sp., and combination of nitrifying and denitrifying bacteria application in controlling the environment of vannamei shrimp Litopenaeus vannamei. The animals used PL 38 measuring weight (2,45±0,23)g and length (7,7±0,25)cm. Pseudomonas sp . and Stenotrophomonas sp . bacteria used on treatment as many as 150 ml. The study consisted of four treatments with three replications. The treatments were K (control), N (application of nitrifying bacteria in water media), D (application of denitrifying bacteria in water media), and ND (application of nitrifying and denitrifying bacteria in water media). The addition of nitrifying and denitrifying bacteria in vannamei shrimp water media can improve water quality, increase growth performance, and reduce stress on vannamei shrimp. The best results was application of an integrated bacteria of nitrifying type Pseudomonas sp. and denitrifying bacteria type Stenotrophomonas sp.
Keyword: growth, Litopenaeus vannamei, Pseudomonas sp, Stenotrophomonas sp

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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