Judul: Evaluasi kesesuaian lahan untuk tanaman alpukat (Persia americana Mill) pada andosol Sukamantri, latosol Ciawi dan latosol Dramaga, Bogor
Abstrak: Today in Indonesia, avocado crop still represent as a farm yard, not yet cultivated commercially in agribusiness scale. Spreading not yet flattened and rather tardy, only two provinces that are West Java and East Java, which becoming especial centre production in Indonesia.
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Judul: Evaluation of the Use of Inorganic, Organic, and  Biofertilizers on the Growth of Avocado Plants (Persea americana Mill.) at  Superavo Orchard, Subang
Abstrak: Peningkatan jumlah produksi alpukat dipengaruhi oleh efektivitas pemupukan. Pemupukan adalah hal terpenting dalam pertanian untuk meningkatkan nutrisi tanaman, mencapai tinggi hasil, dan perubahan lingkungan tanah. Efektivitas kombinasi pupuk anorganik dan pupuk hayati diperlukan untuk meningkatkan kualitas dan kuantitas tanaman serta memperkecil peluang terjadinya degradasi lahan. Rancangan percobaan yang digunakan adalah rancangan acak kelompok (RAK) dengan faktor tunggal berupa pemupukan. RAK ini mempunyai sembilan taraf perlakuan, yaitu: 1) kontrol (tanpa pupuk NPK dan hayati), 2) pupuk NPK 100%, 3) pupuk NPK 50%, 4) pupuk NPK 100% + pupuk hayati 100%, 5) pupuk NPK 100% + pupuk hayati 50%, 6) pupuk NPK 50% + pupuk hayati 100%, 7) pupuk NPK 50% + pupuk hayati 50%, 8) pupuk hayati 100%, 9) pupuk hayati 50%. Perlakuan ini diulang sebanyak lima ulangan. Pupuk dasar yang digunakan, yaitu pupuk kandang sebanyak 1,25 kg/pohon. Hasil siginifikan terjadi pada laju tinggi tanaman, jumlah cabang tersier, N-total, dan aktivitas invertase tanah. Secara keseluruhan perlakuan terbaik adalah kombinasi dari pupuk NPK dan pupuk hayati khususnya pada perlakuan P3, yaitu kombinasi antara NPK 100% dan pupuk hayati 100%. Hal ini terlihat pada pertumbuhan vegetatif tanaman alpukat serta hasil analisis kimia dan biologi tanah yang meningkat., Increasing the amount of avocado production is influenced by the effectiveness of fertilization. Fertilization is the most important thing in agriculture to improve plant nutrition, achieve high yields, and change the soil environment. The effectiveness of the combination of inorganic fertilizer and biofertilizer is needed to improve the quality and quantity of plants and reduce the chances of land degradation. The experimental design used was a randomized block design (RBD) with a single factor in fertilization. This RAK has nine treatment levels, namely: 1) control (without NPK and biofertilizer), 2) 100% NPK fertilizer, 3) 50% NPK fertilizer, 4) 100% NPK fertilizer + 100% biofertilizer, 5) NPK fertilizer 100% + 50% biofertilizer, 6) 50% NPK fertilizer + 100% biofertilizer, 7) 50% NPK fertilizer + 50% biofertilizer, 8) 100% biofertilizer, 9) 50% biofertilizer. This treatment was repeated five times. The basic fertilizer used, namely manure as much as 1.25 kg/tree. Significant results occurred in plant height, the number of tertiary branches, total N, and soil invertase activity. Overall, the best treatment was a combination of NPK fertilizer and biological fertilizer, especially in the P3 treatment, namely a combination of 100% NPK and 100% biological fertilizer. This can be seen in the vegetative growth of avocado plants and the soil's chemical and biological analysis, which have increased.
Keyword: Effectiveness, Fertilization, Soil chemical properties analysis, Soil  biological analysis

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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