Judul: Kepadatan dan Persebaran Parmarion pupillaris pada 10 Jenis Sayuran di Desa Dlangu, Kecamatan Trawas, Kabupaten Mojokerto
Abstrak: Sayuran adalah salah satu komoditas hortikultura yang memiliki umur relatif pendek. Dalam budidaya sayuran, hama menjadi permasalahan. Salah satu hama yang sering menyerang sayuran adalah Parmarion puppilaris (Mollusca) yang merupakan siput semi telanjang. Siput ini memiliki mantel dan cangkang transparan berbentuk tonjolan di bagian punggung. Siput ini sering ditemukan memakan bagian daun, batang, bunga dan buah pada sayuran. Tujuan penelitian ini adalah mempelajari pola persebaran, kepadatan, aktivitas makan dan persebaran ukuran Parmarion pupillaris pada 10 jenis sayuran di Desa Dlangu, Kecamatan Trawas, Kabupaten Mojokerto. Penentuan titik-titik pengamatan dilakukan secara acak dengan menentukan tiga titik per jenis tanaman. Pada titik yang dipilih dibuat plot 1m x 1m dan diamati sebanyak tiga ulangan. Pengamatan aktivitas makan dilakukan pada malam hari. Pengukuran panjang tubuh dilakukan secara langsung pada saat pengamatan. Analisa data kepadatan dan pola persebaran menggunakan metode kuadrat dan Indeks Morisita. Hasil penelitian ini menunjukan kepadatan Parmarion pupillaris tertinggi pada tanaman tomat (Solanum lycopersicum) sebesar 8,7 ind/m2, sedangkan kepadatan terendah terdapat pada jagung (Zea mays) sebesar 0,5 ind/m2. Parmarion pupillaris banyak ditemukan dengan ukuran sedang dan kecil. Pola persebaran siput berdasarkan Indeks Morisita dikategorikan mengelompok.
Keyword: Hama, Hortikultura, siput semi telanjang, kepadatan, percobaan

Judul: Kepadatan dan Persebaran Deroceras laeve dan Meghimatium bilineatum pada 10 Jenis Sayuran di Agropolitan, Cipanas
Abstrak: Deroceras laeve and Meghimatium bilineatum are slugs which are pest, that attacks the vegetables crop. The aims of this research is to study the density and distribution (pattern, feeding activity, and size) of D. laeve and M. bilineatum on 10 types of vegetables at Agropolitan, Cipanas. Sampling was conducted by quadrat method randomly. The highest density of D. laeve was 13.33 ind/m2 on Allium fistulotum and the lowest was 4 ind/m2 on Cripsum frutescens. The highest density of M. bilineatum was 6.22 ind/m2 on Solanum lycopersicum whereas the lowest was 0.56 ind/m2 on Daucus carota. Distribution Pattern of D.laeve and M. bilineatum is group. Distribution of D. laeve of small size (< 1.5 cm), medium (1.5−2.5 cm), and large (> 2.5 cm) were found in 9 different types of vegetables. Distribution of M. bilineatum of small size (< 2 cm) are rare, while the medium size (2−4 cm) and large (> 4 cm) were found in the 4 types of vegetables. Both D. laeve and M. bilineatum were prefer to eat leave than stems and tuberous root.
Keyword: Deroceras laeve, Meghimatium bilineatum, density, distribution

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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