Judul: Serangan Hama Penting dan Keanekaragaman Artropoda Musuh Alami pada Tanaman Padi Budidaya PHT dan Konvensional
Abstrak: Budidaya tanaman padi dan pengendalian OPT berhubungan dengan hasil yang diperoleh petani. Beberapa petani di Jawa Timur telah menerapkan praktek pengendalian hama terpadu (PHT) pada budidaya padi tetapi beberapa lainnya masih menerapkan teknik konvensional. Penelitian ini bertujuan mengamati serangan hama penting penting dan keanekaragaman artropoda musuh alami di sawah yang ditanam dengan teknik PHT dan konvensional. Penelitian dilakukan dengan mengamati lahan sawah milik petani di Jawa Timur dari Maret sampai Juni 2015. Pengamatan dilakukan dengan metode pengamatan langsung, pitfall trap, yellow pan trap, dan pengambilan dengan jaring serangga. Hasil penelitian menunjukkan bahwa serangan hama utama dan keanekaragaman artropoda musuh alami tidak berbeda antara padi yang dibudidayakan dengan teknik PHT dengan teknik konvensional. Hama utama yang ditemukan pada lahan padi adalah wereng batang cokelat (WBC), kepinding tanah, dan penggerek batang padi kuning. Keanekaragaman dan keseragaman artopoda musuh alami pada lahan padi berada pada kategori rendah
Keyword: Conventional control, Integrated pest management, Natural enemies, Rice pests, Rice fields, Pest and diversity, Kepinding tanah, Anthropods, Pest management, Wereng batang ciklat

Judul: Population of Plant-hoppers and Spiders in Biointensive and Conventional Rice Croping
Abstrak: Padi merupakan salah satu tanaman serelia penting yang digunakan sebagai makanan pokok sebagian besar penduduk dunia. Padi tergolong dalam tanaman pangan berupa rumput berumpun dan memiliki kemampuan beradaptasi yang tinggi pada berbagai kondisi lingkungan. Penelitian bertujuan mengetahui perbandingan populasi hama wereng dan populasi laba-laba pada pertanaman padi biointensif dan konvensional di Kampung Darim, Kecamatan Terisi, Kabupaten Indramayu, Provinsi Jawa Barat. Metode penelitian yang digunakan adalah metode pengamatan langsung dilakukan dengan menetapkan titik pengamatan secara terpilih yang mewakili bagian tengah lahan sawah dengan ukuran 10 m x 10 m. Pada setiap lahan sawah ditentukan 100 grid pengamatan, grid pengamatan berukuran 1 m2. Data diolah dan dianalisis menggunakan aplikasi Microsoft excel 2013. Hasil penelitian menunjukkan bahwa populasi wereng lebih tinggi pada lahan pertanaman padi dengan perlakuan biointensif, populasi laba-laba lebih tinggi pada lahan pertanaman padi dengan perlakuan biointensif. Spesies yang ditemukan yaitu Araneus inustus, Neoscona theisi, Atypena adelina, Pardosa pseudoannulata, Tetragnathidae sp., Oxyopes javanus, dan Harmochirus sp. Dominasi spesies yang ditemukan yaitu Atypena adelina baik pada lahan dengan perlakuan biointensif maupun konvensional. Famili yang mendominasi pada pada lahan dengan perlakuan biointensif maupun konvensional adalah Famili Araneidae., Rice is one of the important cereal crops which is used as a staple food for most of the world's population. Rice is classified as a food crop in the form of clump grass and has high adaptability to various environmental conditions. This study aims to determine the comparison of planthopper populations and spider populations in biointensive and conventional rice plantations in Darim Village, Terisi District, Indramayu Regency, West Java Province. The research method used is a direct observation method carried out by determining selected observation points that represent the middle of the rice field with a size of 10 m x 10 m. In each rice field, 100 observation grids are determined, the observation grid is 1 m2 in size. The data was processed and analyzed using the Microsoft Excel 2013 application. The results showed that the planthopper population was higher on rice plantations with biointensive treatment, the spider population was higher on rice plantations with biointensive treatment. The species found were Araneus inustus, Neoscona theisi, Atypena adelina, Pardosa pseudoannulata, Tetragnathidae sp., Oxyopes javanus, and Harmochirus sp. The dominant species found was Atypena adelina both on land with biointensive and conventional treatment. The family that dominates on land with biointensive and conventional treatment is the Araneidae family.
Keyword: dominasi, keragaman, musuh alami

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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