Judul: Aplikasi kalsium untuk mengendalikan cemaran getah kuning pada buah manggis (Garcinia mangostana) di Bogor dan Purworejo)
Abstrak: Gamboge disorder is a main problem in mangosteen production. Result of previous researches showed that calcium fertilization could control gamboge disorder. This experiment was conducted to get lower effective dosage of calcium in two locations i.e., Bogor and Purworejo. The experiment was held from October 2013 to March 2014 in Leuwiliang-Bogor and Kaligesing-Purworejo. Observation of physical and chemical quality was conducted in Postharvest Laboratory, Department of Agronomy and Horticulture. The design of this expermient is Randomized Completely Block Design with one factor. The factor is calcium dosage: 0 kg Ca2+/tree, 1.5 kg Ca2+/tree, 3 kg Ca2+/tree. The result showed that application of calcium decreased the gamboge disorder in two locations. The effective dosage which could decrease the gamboge disorder in Bogor and Purworejo is 1.5 kg Ca2+/tree. The result also showed that application of calcium didn’t affect total soluble solid and total titrated acid.
Keyword: Bogor Agricultural University (IPB), Purworejo, Bogor, calcium, disorder gamboge, mangosteen

Judul: Control of gamboge disorder and improved quality of mangosteen fruit through application of two calcium sources in different dosage
Abstrak: Gamboge disorder is a major problem limiting marketable yield of mangosteen fruit. It is known to be related to low calcium content. Result of previous studies indicate that calcium soil application could increace calcium content in the fruit exocarp and reduce yellow latex in the fruit peel, but ineffective in the flesh. It is known that calcium application could not be sufficient for fruit calcium. Fulfillment of calcium in plants is influenced by the source of calcium and its dosage applied. An experiment was conducted to determine the proper combination of calcium source and its dosage in reducing yellow latex of fruit peel and flesh, also improving fruit quality. Implementations of the experiments conducted in the Kecamatan Kota Agung, Kabupaten Tanggamus, Lampung. Factorial experiment was designed with two factors: Calcium sources (calcitic lime (CaCO3) and dolomitic lime (CaMg(CO3)2) and calcium dosage (0, 2, 4, 6 ton ha-1 Ca). Calcium applied to the soil at blooming period. The experiment was laid out on a randomized complete block design. Leaves and fruits were sampled at harvesting period. Observation of the yellow latex in aryl and fruit peel, fruit physical properties carried out on the variables weight, diameter, fruit hardness, total dissolved solids, total titration acid, and preparation of samples for chemical analysis conducted at PKBT laboratory. Results indicated that application of dolomitic lime with calcium doses of 2 ton Ca ha-1 could increase calcium content of the fruit pericarp (especially exocarp) and reduce yellow latex in the fruit peel and flesh. Calcium application did not affect the physical and chemical properties of the fruit.
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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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