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: Production Performance and Bussines of Apartment System Soka Crab Farming with Various Acclimatization Techniques
Abstrak: Budidaya kepiting soka dalam boks apartemen dengan recirculated aquaculture system (RAS) masih menggunakan benih hasil tangkapan alam. Lokasi sumber benih dengan kegiatan budidaya seringkali berjauhan, sehingga dibutuhkan pengangkutan yang umumnya dilakukan secara kering, yang dapat menyebabkan kepiting stres. Pascapengangkutan kepiting membutuhkan aklimatisasi sebelum ditebar ke boks apartemen namun informasi mengenai teknik aklimatisasinya masih terbatas. Penelitian ini bertujuan menganalisis respons fisiologis, tingkah laku, kinerja produksi dan usaha budidaya kepiting soka sistem apartemen dengan berbagai teknik aklimatisasi. Penelitian ini menggunakan rancangan acak lengkap (RAL) dengan tiga perlakuan dan tiga ulangan, yaitu perendaman dan aerasi 60 menit (P1), pencipratan 60 menit (P2), serta pencipratan 30 menit dan perendaman 30 menit (P3). Benih kepiting bakau (Scylla serrata) yang digunakan sebanyak 120 ekor berukuran 40-80 g dan dipelihara selama 30 hari dalam boks apartemen RAS. Kepiting diberi pakan ikan selar kuning satu kali sehari (17.00) secara restrictred (5% dari bobot). Kualitas air dijaga melalui penyifonan sisa pakan dan feses. Paramater penelitian yaitu glukosa hemolim, tingkah laku, tingkat kelangsungan hidup (TKH), laju pertumbuhan mutlak bobot (LPMBb), persentase molting, rasio konversi pakan (RKP), revenue/cost (R/C) dan break event poin (BEP). Perbedaan teknik aklimatisasi tidak berpengaruh terhadap TKH dan LPMBb. Persentase molting dan RKP terbaik diperoleh pada P1 dan P3. Respons fisiologis dan tingkah laku terbaik terdapat pada P3. Kinerja usaha pada semua perlakuan mengalami kerugian dengan R/C <1 dan produksi belum mencapai BEP., Farming soft shell crabs in apartment boxes using a recirculated aquaculture system (RAS) still uses fisheries caught seeds. The location of the seed source and farm activities are often far apart, so transportation is required which is generally carried out in dry condition, which can cause stress to the crabs. Post transportation of crabs requires environmental adjustment (acclimatization) before being stocked in apartment boxes, but information regarding acclimatization techniques is still limited. This research aims to analyze the physiological response, behavior, production performance and culture of soft shell crabs in an apartment system using various acclimatization techniques. This research used a completely randomized design with three treatments and three replications, namely 60 minutes of immersion and aeration (P1), 60 minutes of splashing (P2), and 30 minutes of splashing and 30 minutes of immersion (P3). There were 120 mud crab (Scylla serrata) seed each weighing 40-80 g were reared for 30 days in the RAS apartment boxes. The crabs were given yellow trevally fish once a day (17.00) on a restricted basis (5% of weight). Water quality is maintained through siphoning of leftover feed and feces. The research parameters are hemolytic glucose, behavior, survival rate (SR), absolute weight growth rate, molting percentage, feed conversion ratio (FCR), revenue/cost (R/C) and break event points (BEP). Differences in acclimatization techniques have no effect on SR and absolute weight growth rate. The best molting percentage and FCR were obtained at P1 and P3. The best physiological and behavioral responses are found in P3. Business performance in all treatments experienced losses with R/C <1 and production had not reached BEP.
Keyword: acclimatization, apartement box, mud crab, RAS, stress

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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