Judul: Peningkatan Mutu Bibit Torbangun (Plecranthus amboinicus Spreng.) dengan Pemilihan Asal dan Pemberian Auksin
Abstrak: Torbangun is an indigenous vegetable that its leaves used as herbal plant. Torbangun propagation still done vegetatively by cutting, but it has not been developed. The purpose of this research is to get the best combination part of stem cuttings and auxin concentration, in order to achieve vigor cutting. This research was conducted at Conservation and Biopharmaca Cultivation, Cikabayan IPB, Bogor from January until March 2014. This research consisted of 2 experiments. The first experiment treatments were part of stem cuttings torbangun (tips, central and base) and auxin concentrations (0, 20 and 40 ppm). Second experiment treatments were length of tips cuttings torbangun (3.5, 7, and 10.5 cm) and auxin concentration (0, 20, dan 40 ppm). Because of limited seed, tips cuttings at first experiment was same with tips cuttings with 7 cm length at second experimment. There were 15 combination of treatments, 3 replications and each treatment consisted of 10 cuttings, in this way a total was 450 cuttings. The experiments was laid out in Randomized Completely Block Design – Factorial with two factor. The result of this experiments showed that tips was the best part of stem cuttings to achieve vigor cutting torbangun. All concentrated of auxin until 40 ppm did not affect to cutting’s indicator. 10.5 cm of length tips cuttings was the best to increase long roots and nodes of torbangun
Keyword: seed quality, Plectranthus amboinicus, indigenous, cutting methods

Judul: Pertumbuhan dan Produksi Daun Torbangun (Plectranthus amboinicus Spreng.) dengan Pemupukan Organik dan Pemangkasan
Abstrak: Torbangun is a nutritious crop that increase breast milk because it contains lactagogen. Most study of torbangun plants focuses on pharmacological characteristics of plant. There is a need for research in cultivation techniques using organic fertilizer and pruning. The purpose of this study was to investigate the effect of organic fertilizer and pruning on the growth and leaf production of torbangun plant. This study used randomized block design (RBD) in the first experiment with fertilizer factor and Split plot design in the second experiment with fertilizer and pruning. Both of the experiment used Tukey‟s (Honestly Significant Difference) test. Organic fertilization is divided into 5 levels: without fertilizer, cow manure+rock phosphate, cow manure+rice-hull ash, rock phosphate+rice-hull ash, and cow manure+rock phosphate+rice-hull ash. Pruning is consisted of 2 levels: without pruning and with pruning. The results showed that fertilization using cow manure + rock phosphate + rice-hull ash increased shoot fresh weight of 125.21% compared to without fertilization. Pruning reduced plant biomass and leaf number. Torbangun growth is slow, so harvesting should have been done in a longer interval.
Keyword: 

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.
Keyword: