Judul: Improving the survival rate and the growth performance of the pacific white shrimp (Litopenaeus vannamei, Boone) rare on low salinity medium
Abstrak: Penelitian dilakukan dalam tiga tahap. Penelitian tahap pertama terdiri dari dua seri percobaan. Percobaan pertama bertujuan mengkaji pengaruh penambahan berbagai kadar kalsium pada berbagai salinitas media terhadap sintasan postlarva vaname (Litopenaeus vannamei, Boone). Rancangan yang digunakan adalah model faktorial terdiri enam belas perlakuan dengan 3 ulangan dibedakan berdasarkan penurunan salinitas (0 ppt, 2 ppt, 4 ppt, 6 ppt) dengan penambahan kalsium (0 ppm, 50 ppm, 100 ppm, 150 ppm) dalam media pengencer air tawar. Percobaan kedua merupakan pengulangan dari percobaan pertama pada salinitas akhir 2 ppt melalui evaluasi osmolaritas dan laju metabolisme. Rancangan percobaan menggunakan Rancangan Acak Lengkap terdiri 5 perlakuan berdasarkan penambahan kalsium dalam media yaitu: (A) 0 ppm, (B) 50 ppm, (C) 100 ppm, (D) 150 ppm, dan kontrol (salinitas 25 ppt) dengan 3 ulangan. Benih vaname (PL 20) yang digunakan diperoleh dari balai pembenihan (hatchery) komersial hasil pemijahan dari satu induk dalam upaya meminimalkan variasi unit percobaan. Setiap wadah diisi air bersalinitas 25 ppt yang kemudian diturunkan secara gradual selama 96 jam hingga salinitas perlakuan akhir 0 ppt, 2 ppt, 4 ppt, dan 6 ppt. Sedangkan pada percobaan kedua salinitas akhir yang dituju 2 ppt. Pemberian pakan Artemia dilakukan 4 kali perhari.
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Judul: Pengaruh Penambahan Kalium pada Masa Adaptasi Penurunan Salinitas dan Waktu Penggantian Pakan Alami oleh Pakan Buatan terhadap Performa Pascalarva Udang Vaname (Litopenaeus vannamei)
Abstrak: The objectives of this research were to study the effect of potassium addition during salinity acclimatization from 25 ppt until 2 ppt and natural food substitution time by artificial diet after salinity acclimatization on performance of Litopenaeus vannamei postlarvae. The first experiment was done to determine optimal dosage of potassium which can increase survival and reduce stress level after salinity acclimatization. Animal test used was PL20 of white shrimp (0,001 g). Experimental design used was completely randomized design with four treatments and three replications of different potassium addition level to freshwater : 0 ppm (A), 25 ppm (B), 50 ppm (C) and 75 ppm (D). Dilution of salinity was done in gradual using freshwater during 4 days from 25 ppt to 2 ppt. The research of the second experiment was conducted to determine natural food substitution time by artificial diet after salinity acclimatization which can increase survival and growth. The densities of PL25 white shrimp were 20 PLs/50 liters of 2 ppt media. Design experiment was completely randomized design with five treatments and three replications of food substitution time by artificial diet at day : 1 (A), 7 (B), 14 (C), 21 (D) and full natural food without artificial diet (E) during 28 days rearing period. Artificial diet (40,71% of crude protein) and natural food frozen Chironomus sp (62,76% of crude protein) was used in this experiment. The result of the first experiment indicated that addition of 25 ppm potassium (potassium level in media was 51 ppm) increase survival, also reduce energy cost for osmoregulation and level of stress of PL24 after passing a period of salinity acclimatization during 4 days. The result of the second experiment showed that the use of artificial diet as soon as after salinity acclimatization (PL25) gives best performance production compared to which only that was given natural food Chironomus sp during experiment or with treatment by artificial diet substitution at day-7, day-14 or day-21.
Keyword: Litopenaeus vannamei

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology