Judul: Penentuan dosis pemupukan N, P dan K pada budidaya katuk (Sauropus androgynus (L.) Merr.)
Abstrak: The objective of the research was to determine optimum rate of N, P, and K fertilizer for katuk (Sauropus androgynus (L.) Merr.) production. Experiments were conducted at vegetables garden Darmaga Field Unit University Farm, Bogor Agricultural University from May to December 2010. Treatments were N, P and K fertilizer at rate of 0%, 50%, 100%, 150% and 200% of fertilizer recommendation (100% N = 100 kg N.ha-1, 100% P = 135 kg P2O5.ha-1, 100% K = 135 kg K2O.ha-1). One hundred percent P, 50 % N, and 50 % K were applied before planting, while 25% N and 25% K were applied at 3rd and 6th week after planting. This experiment used randomized completely block design with four replications. Plot size was 5 m x 1.5 m. Katuk cuttings were planted in double rows per plot, with plant spacing of 50 cm x 25 cm. Results showed that N application had no effect on vegetative growth but increased on yield with a linear response pattern. P fertilizer application increased on plant height but had no effect on yields. K fertilizer treatment effected on yield with quadratic respon pattern. Multi-nutrient response approach was not applicable to this experiment, but the results of K fertilization treatment could be used to determine the maximum dose of fertilizer. Based on these formulated, equation was y=-0.0012x2+0.2529x+68.059 for K2O. The optimum rate for K was 105 kg K2O.ha-1.
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Judul: Response of Shade and Fertilizer Dosage on Growth and  Yield of Katuk (Sauropus androgynus (L.) Merr.).
Abstrak: Katuk (Sauropus androgynus (L.) Merr.) adalah salah satu jenis sayuran indigenous di Indonesia yang memiliki potensi untuk dikembangkan sebagai sayuran alternatif untuk memenuhi kebutuhan nutrisi. Penelitian ini bertujuan untuk mengetahui pengaruh intensitas naungan dan dosis pupuk yang sesuai guna meningkatkan pertumbuhan dan hasil produksi katuk. Percobaan dilakukan menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) faktor Split plot dengan petak utama adalah naungan dan anak petak adalah dosis pemupukan. Intensitas naungan terdiri dari 4 taraf, yaitu N0 (tanpa naungan), N1 (naungan 55%), N2 (naungan 65%), dan N3 (naungan 75%). Dosis pemupukan juga terdiri dari 4 taraf, yaitu P1 (50 kg ha-1), P2 (100 kg ha-1), P3 (150 kg ha-1), dan P4 (200 kg ha-1). Penelitian dilakukan dengan 3 ulangan sehingga diperoleh 16 kombinasi, dengan 48 satuan percobaan. Hasil penelitian menunjukkan tidak terdapat interaksi antara naungan dan dosis pemupukan. Perlakuan tunggal dosis pemupukan tidak memberikan pengaruh terhadap seluruh parameter pengamatan. Perlakuan naungan berpengaruh terhadap seluruh peubah pengamatan kecuali pada diameter batang saat pengamatan 2 MST dan 3 MST. Bobot panen komersial yang dipanen pada 8 MST mencapai hasil optimum pada aplikasi naungan 65%. Kata kunci: paranet, sayuran indigenous, dan sayuran komersial, Katuk (Sauropus androgynus (L.) Merr.) is one of the indigenous vegetables in Indonesia which has the potential to be developed as an alternative vegetable to meet nutritional needs. This study aims to determine the effect of shade intensity and appropriate dose of fertilizer to increase growth and yield of katuk production. The experiment was carried out using a completely randomized block design (RKLT) with split plot factors with the main plot being shaded and sub-plots being the dose of fertilization. Shade intensity consisted of 4 levels, namely N0 (without shade), N1 (55%), N2 (65%), and N3 (75% shade). The fertilization dose also consisted of 4 levels, namely P1 (50 kg ha-1), P2 (100 kg ha-1), P3 (150 kg ha-1), and P4 (200 kg ha-1). The study was conducted with 3 replications so that 16 combinations were obtained, with 48 experimental units. The results showed that there was no interaction between shade and fertilization dose. Single treatment of dose fertilization did not give effect on all parameter of observation. Shade treatment affected all observation variables except for stem diameter at 2 WAP and 3 WAP. Commercial harvest weights harvested at 8 WAP achieved optimum yields at 65% shading applications. Keywords: commercial vegetable, indigenous vegetable, and paranet
Keyword: commercial vegetable, indigenous vegetable, paranet

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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