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: Penambahan Feed Additive Berbasis Selenium Organik dalam Pakan terhadap Kinerja Pertumbuhan Udang Vaname Litopenaeus vannamei
Abstrak: Penelitian ini bertujuan mengukur kinerja pertumbuhan udang vaname (Litopenaeus vannamei) yang diberi suplementasi selenium organik. Terdapat tiga perlakuan berbeda, yaitu K (pakan tanpa feed additive), A (selenium organik dan zinc), dan B (selenium organik). Penelitian ini menggunakan rancangan acak lengkap dengan tiga perlakuan dan empat ulangan. Udang yang digunakan adalah udang vaname dengan ukuran rata-rata 1,5 g sebanyak 15 ekor/akuarium. Pemeliharaan udang uji dilakukan selama 56 hari pada akuarium berukuran 60 × 40 × 45 cm3 . Udang uji diberi pakan lima kali sehari, dengan metode pemberian pakan berdasarkan feeding rate yaitu 5-8% yang disesuaikan dengan biomassa udang setiap 14 hari. Hasil penelitian ini menunjukan nilai laju pertumbuhan harian, pertambahan bobot harian, rasio konversi pakan, dan rasio efisiensi protein lebih baik pada udang yang diberikan perlakuan dibandingkan kontrol. Udang vaname yang diberi pakan perlakuan A (selenium organik dan zinc) memperlihatkan kinerja pertumbuhan terbaik dibanding perlakuan lainnya., The experiment was conducted to measure the growth performance of white shrimp (Litopenaeus vannamei) given organic selenium supplementation. There were three different treatments, namely K (feed without feed additive), A (organic selenium and zinc), and B (organic selenium). This study used a completely randomized design with three treatments and four replications. The shrimp used were vaname shrimp with an average size of 1.5 g as many as 15 fish/aquarium. The rearing of the test shrimp was carried out for 56 days in an aquarium measuring 60 × 40 × 45 cm3. The test shrimp were fed five times a day, with a feeding method based on a feeding rate of 5-8% adjusted for shrimp biomass every 14 days. The results of this study showed that the daily growth rate, daily weight gain, feed conversion ratio, and protein efficiency ratio were better in the treated shrimp than the control. Vannamei shrimp fed with treatment A (organic selenium and zinc) showed the best growth performance compared to other treatments.
Keyword: growth, selenium, white shrimp, zinc

Judul: Invers Drazin dari Matriks Toeplitz Singular
Abstrak: Matriks Toeplitz adalah matriks yang setiap unsur pada diagonal utama bernilai sama dan setiap unsur pada subdiagonal yang bersesuaian dengan diagonal utama juga bernilai sama. Matriks singular adalah matriks yang tidak bisa ditentukan inversnya. Akan tetapi, dapat diupayakan untuk ditentukan inversnya menggunakan invers matriks yang diperumum. Invers Drazin merupakan salah satu jenis invers matriks yang diperumum. Pada karya ilmiah ini ditentukan invers Drazin dari matriks Toeplitz singular dengan menggunakan metode Leverrier Faddeev. Kemudian, ditentukan invers Drazin dari matriks Toeplitz singular yang direpresentasikan sebagai penjumlahan segitiga bawah dan segitiga atas matriks Toeplitz berdasar pada teorema Gohberg dan Semencul., Toeplitz matrix is a matrix in with element on the main diagonal has the same value and on the subdiagonal corresponding to the main diagonal also has the same value. Singular matrix is a matrix that has no inverse. However, it can be attempted to determine the inverse using a generalized inverse matrix. Inverse Drazin is a type of generalized matrix inverse. This paper discussed the inverse Drazin for a singular Toeplitz matrix using the Leverrier Faddeev method. Then, the Drazin inverse of the singular Toeplitz matrix which is represented as a sum of products of lower and upper triangular Toeplitz matrix based on Gohberg and Semencul theorem.
Keyword: inverse Drazine, singular Toeplitz matrix