Judul: Hama dan Penyakit Tanaman Pohpohan (Pilea Trinervia Wight) di Kecamatan Taman Sari, Kabupaten Bogor
Abstrak: Pohpohan (Pilea trinervia) is one of important indigenous vegetables. Pests and diseases on pohpohan have not been studied. The aim of this research was to study pests and diseases of pohpohan, management of pests and diseases, and cultivation practice which has been conducted at two villages in Bogor. Interview using structured questionnaire was done on 20 farmers. Field observation at two different locations by taking 10 plants diagonally with total of 20 pohpohan plants in once observation was carried out thereafter, identification, taking pests and disease on plant sample, collection and data analysis were conducted. There were not insect pests on sampled plants. Symptoms of pest were found on leaf such as shot leaf hole caused by famili Noctuidae, leaf chunks caused by famili Acrididae, and leaf white spot caused by famili Cicadellidae. Diseases of pilea were stem rot caused by R. solani Kuhn. Leaf spot caused by Phyllosticta sp.. Antrachnose caused by Colletotrichum sp.. There was no specific measures to control plant pests and diseases. Pilea was cultivated in agroforestry system under pinus and damar stand
Keyword: Bogor Agricultural University, agroforestry, attack symptoms of insect, indigenous vegetables, pests and diseases, pohpohan

Judul: Hama dan Penyakit Tanaman di Taman Bogor
Abstrak: Taman merupakan sebidang lahan terbuka dengan luasan yang didalamnya ditanami pohon, perdu, semak, dan rerumputan yang secara kreasi dapat dikombinasikan dari bahan lainnya. Dalam sebuah taman terdapat berbagai jenis tanaman yang tumbuh. Umumnya jenis tanaman yang banyak terdapat di taman kota ialah tanaman hias. Tanaman yang terserang hama dan penyakit akan menunjukkan gejala yang akan mengganggu nilai estetika tanaman yang tersedia serta akan mengganggu kenyamanan para pengunjung taman. Penelitian ini bertujuan mengetahui, mengamati, dan mengidentifikasi hama dan penyakit pada pertanaman di Taman Heulang Kota Bogor dan Taman Himawari Kampus IPB Dramaga dengan pengamatan langsung dilapang dan mengidentifikasi berbagai hama dan penyakit yang ditemukan. Hama dan penyakit yang paling banyak ditemui di Taman Himawari adalah Bothrogonia addita, Kallitaxila granulata, Phenacoccus sp., Acanalonia conica, Omiodes indicata, Phaneroptera nana, Cercospora sp, Alternaria sp., dan Colletotrichum spp., sedangkan hama dan penyakit yang paling banyak ditemui di Taman Heulang adalah Bothrogonia addita, Kallitaxila granulata, Aphis gossypii, Doleschallia bisaltide, Puccinia sp., dan Colletotrichum spp., Park is an open land with an area planted with trees, shrubs, bushes, and grass which can be creatively combined with other materials. In a park, there are various types of plants growing. Generally, the types of plants that are often found in city parks are ornamental plants. Plants that are attacked by pests and diseases will show symptoms that will disrupt the aesthetic value of the plants and will disturb the comfort of park visitors. This research aims to find out, observe, and identify pests and diseases in plantations in Heulang Park, Bogor City, and Himawari Park, IPB Dramaga Campus by direct observation in the field and identifying the various pests and diseases found. The pests and diseases most commonly found in Himawari Park are Bothrogonia addita, Kallitaxila granulata, Phenacoccus sp., Acanalonia conica, Omiodes indicata, Phaneroptera nana, Cercospora sp., Alternaria sp., and Colletotrichum spp., while the most common pests and diseases found in Heulang Park were Bothrogonia addita, Kallitaxila granulata, Aphis gossypii, Doleschallia bisaltide, Puccinia sp., and Colletotrichum spp.
Keyword: Bothrogonia addita, Colletotrichum spp., Kallitaxila granulata, Pseuderanthemum reticulatum, Zinnia elegans

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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