Judul: Performance of Soft Shell Crab Production and Cultivation Business in Apartment Systems with Different Seed Sources
Abstrak: Pengembangan budidaya kepiting bakau di kawasan perkotaan (urban aquaculture) menggunakan sistem apartemen dengan resirkulasi air masih membutuhkan benih dari hasil tangkapan alam. Benih dari lokasi penangkapan yang berbeda akan mempengaruhi kelangsungan hidup, pertumbuhan, dan produktivitas kepiting bakau dalam sistem akuakultur, terkait dengan kondisi habitat asal kepiting, cara penangkapan, penanganan dan transportasi hasil tangkapan. Kepiting bakau berukuran 50-120 g sebanyak 90 ekor didatangkan dari Bekasi, Tangerang, dan Subang. Kepiting bakau ditangkap di tambak tradisional dan hutan mangrove menggunakan bubu dan pancingan, lalu ditampung selama 2- 3 jam pada drum plastik, karung, dan boks stirofoam, kemudian diangkut secara kering menggunakan keranjang berukuran 48 × 35,5 × 16,5 cm, selanjutnya diaklimatisasi dengan metode pencipratan dan perendaman. Kepiting bakau kemudian dipelihara dalam sistem apartemen selama 30 hari, dan diberi makan ikan rucah selar kuning sebanyak 2-5 g/ekor secara at satiation satu kali dalam sehari pada pukul 17.00 WIB. Hasil penelitian menunjukkan sumber benih dari Kabupaten Bekasi, Tangerang, Subang tidak berpengaruh terhadap kinerja produksi kepiting soka, yaitu kelangsungan hidup 73,33±5,77%, 70,00±10,00%, dan 50,00±10,00% dengan produksi kepiting soka antara 6,67-33,33%. Hasil penjualan kepiting belum mencapai titik impas, kecuali pada kepiting yang berasal dari Tangerang., Development of mangrove crab cultivation in urban areas (urban aquaculture) using an apartment system with water recirculation still requires seeds from natural catch. Seeds from different fishing locations will influence the survival, growth and productivity of mud crabs in the aquaculture system, related to the conditions of the crab's native habitat, methods of catching, handling and transporting the catch. The 90 mangrove crabs measuring 50-120 g were imported from Bekasi, Tangerang and Subang. Mangrove crabs are caught in traditional ponds and mangrove forests using traps and fishing rods, then stored for 2-3 hours in plastic drums, sacks and styrofoam boxes, then transported dry using baskets measuring 48 × 35.5 × 16.5 cm, then acclimatized by splashing and immersion methods. Mangrove crabs are then kept in an apartment system for 30 days, and fed 2-5 g of yellow trevally trash fish/head at satiation once a day at 17.00 WIB. The results of the research showed that seed sources from Bekasi, Tangerang, Subang Regencies had no effect on the production performance of soft shell crabs, namely survival of 73.33 ± 5.77%, 70.00 ± 10.00%, and 50.00 ± 10.00% with soft shell crab production between 6.67-33.33%. The sales of crabs have not yet reached the break-even point, except for crabs originating from Tangerang.
Keyword: crab catching, molting, survival

Judul: Upaya Peningkatan Frekuensi Molting pada Usaha Budidaya Kepiting Bakau Soka Sistem Apartemen
Abstrak: Upaya meningkatkan frekuensi molting pada budidaya kepiting soka (soft carapace, cangkang lunak) dalam sistem apartemen sudah banyak dilakukan dan perlu terus dikembangkan. Penelitian ini bertujuan menganalisis perlakuan autotomi dan pemberian bayam terhadap kinerja produksi dan kinerja usaha kepiting soka pada sistem apartemen RAS (recirculated aquaculture system). Penelitian ini mengunakan rancangan acak lengkap (RAL) yang terdiri atas tiga perlakuan, yaitu kontrol (PK), autotomi (PA), dan pemberian bayam melalui pakan (PB). Setiap perlakuan penelitian diulang empat kali, dan setiap ulangan terdiri atas 10 boks (32 x 39 x 14 cm) yang masing-masing berisi satu ekor kepiting bakau berukuran 50-90 g, sehingga diperlukan sebanyak 120 ekor. Perlakuan autotomi dilakukan dengan menekan bagian ujung pangkal kaki jalan dan capit kepiting bakau dengan penjepit, sehingga kepiting menanggalkan kaki jalan dan capit tersebut. Perlakuan pemberian bayam (Amaranthus hybridus) dilakukan melalui pakan buatan berbahan dasar ikan selar kuning (Selaroides leptolepis). Ikan selar kuning dan bayam raja dihaluskan, kemudian ditambahkan tepung tapioka sebagai binder, lalu dibentuk seperti bakso dan direbus. Perlakuan kontrol merupakan kepiting tanpa perlakuan dengan pakan ikan rucah. Pemberian pakan dilakukan setiap pukul 17.00 WIB, sebanyak 5% dari biomassa kepiting. Parameter yang diamati selama pemeliharaan terdiri dari kinerja produksi (persentase molting, waktu dan jumlah molting, tingkat kelangsungan hidup, pertambahan bobot, rasio konversi pakan dan fisika kimia air (suhu, salinitas, pH, oksigen terlarut (DO), total ammonia nitrogen (TAN)). dan kinerja usaha (harga pokok produksi, penerimaan, biaya total, revenue/cost ratio (RC), keuntungan, break event point (BEP), payback period (PP)). Perlakuan autotomi mampu memberikan presentase molting, dan tingkat kelangsungan hidup yang paling tinggi di antara semua perlakuan dengan nilai masing-masing mencapai 96,67% dan 96,67%, serta kinerja usaha kepiting soka yang lebih baik dibandingkan dengan perlakuan kontrol dan perlakuan pemberian bayam., Efforts to increase the frequency of molting in soft carapace (soft shell) crab cultivation in apartment systems have been widely carried out and need to continue to be developed. This research aims to analyze autotomy treatment and giving spinach on the production performance and business performance of soft shell crabs in the RAS (recirculated aquaculture system) apartment system. This study used a completely randomized design (CRD) consisting of three treatments, namely control (PK), autotomy (PA), and giving spinach through feed (PB). Each research treatment was repeated four times, and each replication consisted of 10 boxes (32 x 39 x 14 cm) each containing one mud crab measuring 50-90 g, so 120 individuals were needed. Autotomy treatment is carried out by pressing the tip of the base of the mud crab's walking legs and claws with tweezers, so that the crab removes the walking legs and claws. The treatment with spinach (Amaranthus hybridus) was carried out using artificial feed made from yellow trevally (Selaroides leptolepis). The yellow trevally and king spinach are mashed, then tapioca flour is added as a binder, then shaped like meatballs and boiled. The control treatment was crab without treatment with trash fish feed. Feeding is carried out every 17.00 WIB, as much as 5% of the crab biomass. Parameters observed during rearing consisted of production performance (molting percentage, time and number of moltings, survival rate, weight gain,
Keyword: autotomy, business performance, production performance, spinach

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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