Judul: Quality of Frass from Samia cynthia ricini Silkworm by Feeding Castor Leaves Using Different Activators
Abstrak: Limbah frass ulat sutra eri (Samia cynthia ricini) kurang dimanfaatkan, pemeliharaan 20.000 – 25.000 larva menghasilkan frass sekitar 500 kg. Frass dapat digunakan sebagai bahan pupuk organik untuk meningkatkan unsur hara tanah. Penelitian ini bertujuan menganalisis kualitas pupuk frass ulat sutra eri dengan pemberian pakan daun jarak kepyar dengan aktivator EM4 dan PGPR. Peubah yang diamati dari pupuk frass dengan penambahan EM4 dan PGPR, yaitu sifat fisik dan kimia selama 21 hari yang diamati pada hari ke-0, 7, 14, dan 21, serta uji efektivitas pupuk frass pada tanaman kangkung selama 28 hari. Hasil penelitian menunjukkan sifat fisik pupuk frass memenuhi standar SNI pada pH berkisar 4-9, tekstur remah, dan aroma sedikit asam. Penambahan EM4 dan PGPR meningkatan unsur N dan K, sedangkan P dan rasio C/N mengalami penurunan. Penggunaan pupuk frass pada tanaman kangkung menunjukkan hasil tidak berbeda nyata (P>0,05) terhadap tinggi tanaman, diameter batang, jumlah daun, dan bobot segar. Pupuk frass berpotensi menggantikan pupuk kimia berdasarkan peubah yang diamati., Eri silkworm (Samia cynthia ricini) frass waste is underutilized, rearing 20,000 – 25,000 larva produces around 500 kg of frass. Frass can be used as an organic fertilizer to increase soil nutrients. This research aims to analyze the quality of eri silkworm frass fertilizer by feeding it with castor leaves with EM4 and PGPR activators. The variables observed from frass fertilizer with the addition of EM4 and PGPR, included the physical and chemical properties for 21 days which were observed on days 0, 7, 14, and 21, as well as testing the effectiveness of frass fertilizer on water spinach plants for 28 days. The research results show that the physical properties of frass fertilizer meet SNI standards at a pH ranging from 4-9, a crumbly texture, and a slightly sour aroma. The addition of EM4 and PGPR increased the N and K elements, while P and the C/N ratio decreased. The use of frass fertilizer on water spinach plants showed that the results were not significantly different (P>0.05) on plant height, stem diameter, number of leaves and fresh weight. Frass fertilizer has the potential to replace chemical fertilizer based on the observed variables.
Keyword: EM4, Samia cynthia ricini, castor leaves, eri silkworm frass, PGPR

Judul: Quality of Eri Silkworm Frass Fertilizer (Samia  cynthia ricini) with EM4 and PGPR Activators
Abstrak: Eri silkworm (Samia cynthia ricini) has the potential to be cultivated in Indonesia. Silkworm cultivation in a year produces 250-300 kg of frass which has potential cause problems for cultivation and environment. Frass has high nutrients so potentially used as fertilizer for agricultural. This study aims to analyze the quality of silkworm frass fertilizer with EM4 and PGPR activators on spinach. The production of fertilizer is accelerated by using activators EM4 and PGPR. The physical and chemical properties of fertilizers were analyzed descriptively. Fertilizer effectiveness experiment on watercress was carried out using a completely randomized design (CRD). At 4th week the physical properties of the fertilizer changed texture and pH according to SNI but still had a slightly sour smell and black color. Using EM4 and PGPR showed increase NPK according to SNI. The usage frass silkworm S. c. ricini fertilizer had significant effect on height, stem diameter, number of leaves, fresh weight, water shoots, water spinach leaves based on Tukey's advanced test on level of 5%. Therefore, Eri silkworm frass fertilizer has potentially used as fertilizer for horticultural in spinach as experimental plant.
Keyword: EM4, Eri silkworm frass, PGPR, Samia cynthia ricini, Spinach

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
Keyword: