Judul: Aplikasi pupuk kalsium dan boron untuk mengurangi getah kuning pada buah Manggis (Garcinia mangostana L.)
Abstrak: The yellow sap contamination causes low quality of mangosteen. Yellow sap contamination occurs due to weak cell walls in the fruit. Weak cell walls caused by low calcium and boron. Calcium has a function to strengthen the integrity of the cell wall and boron provide the stability maintenance of the cell wall. This research aims to examine the combination of calcium and boron with a low dose to reduce yellow sap contamination in mangosteen. The research was located in 3 mangosteen orchard in Cigudeg, Citeureup, Sukabumi, and analysis of samples in Post Harvest Laboratory of Bogor Agricultural University in November 2014 to March 2015. The research was designed by Randomized Complete Block Design (RCBD) with one factor of the combination of calcium and boron dose. The treatment consisted of 5 levels that repeated 4 times with each repetition consisted of one tree so that the number of mangosteen tree is 20 trees in each experimental orchard. In each tree, 20 fruits were collected randomly. The combination of fertilizers that used in this research was without fertilizer (control), 1 kg Ca / tree + 0.047 g B / tree, 1 kg Ca / tree + 1.553 g B/ tree, 1.5 kg Ca / tree + 0.047 g B / tree , and 1.5 kg Ca / tree + 1.553 g B / tree. The results of this research indicated that the most effective dose to reduce contamination of yellow sap in mangosteen in three experimental orchard was a dose of 1.5 kg Ca / tree + 1.553 g B / tree. The application of calcium and boron at a dose of 1.5 kg Ca/tree + 1.553 g B/tree significantly reduced scores and percentage of yellow sap contamination on peel and aryl of fruit, and did not affect the physical and chemical quality of mangosteen fruits.
Keyword: Bogor Agricultural University, cell wall, fertilization, fruit quality, mineral nutrient

Judul: Studi aplikasi Kalsium dan Boron terhadap pengendalian getah kuning pada buah manggis (Garcinia mangostana L.
Abstrak: New and exciting developments in research of mangosten yellow latex in the past few years greatly contributed to better understanding of the methode to control gamboge in mangosten fruits. A field experiment was conducted to understanding and quantifying the effect of boron (B) and calcium (Ca) application to control yellow latex or gamboges on manggosten fruit. There are five treatments and one control as follow: (1) no fertilizer applied as control, (2) 5.79 kg Ca.tree-1.year-1 applied by soil application (3) 5.79 kg Ca.tree-1.year-1 applied by soil application + 1.553 g B.tree-1 .year-1 applied by soil application, (4) 5.79 kg Ca.tree-1.year-1 applied by soil application + 0.047 g B.tree-1.year-1 applied by foliar application, (5) 1.553 g B.tree-1 .year-1 applied by soil application, (6) 0.047 g B.tree-1.year-1 applied by foliar application. The experiment was laid out on a randomized complete block design. The treatment of 5.79 kg Ca.tree- 1.year-1 applied by soil application + 1.553 g B.tree-1 .year-1 applied by soil application significantly affect to reduced yellow latex in aril till to 0%, reduced yellow latex scoring in aril, increasing boron content in endocarp. However they were not significant affect on fruit weight, fruit diameter, fruit fluident, total soluble solid (TSS), total acid titrated (TAT), Ca in leaves, Ca in pericarp, B in excocarp, and B in mesocarp.
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: