Judul: Diversity of Insect Species at Different Ages of Rhizophora mucronata Stands Grown With Guludan Technique in Muara Angke, Jakarta
Abstrak: Serangga merupakan salah satu makhluk hidup dengan jumlah terbesar di dunia yang memiliki sejumlah manfaat. Namun, masih banyak serangga yang belum teridentifikasi contohnya serangga pada ekosistem mangrove. Setiap umur tegakan memiliki perbedaan struktur vegetasi, sehingga penelitian keanekaragaman serangga pada setiap perbedaan umur R. mucronata penting dilakukan. Pengambilan sampel dilakukan secara purposive sampling dengan mengambil tiga sampel guludan yang berukuran 5 m  10 m. Pada masing-masing sampel dilakukan sensus untuk mengukur diameter dan tinggi R. mucronata pada umur 17, 13, 9, 4 tahun untuk selanjutnya dilakukan analisis vegetasi. Penangkapan serangga dilakukan dengan menggunakan yellow-pan trap lalu diidentifikasi sampai tingkat morfospesies. Hasil menunjukkan terdapat hubungan antara umur tegakan yang berbeda terhadap keanekaragaman dan kelimpahan serangga. Umur muda memiliki kelimpahan dan keanekaragaman serangga lebih tinggi dibandingkan umur tua dan umur R. mucronata 13 tahun memiliki kelimpahan tertinggi yang didominasi oleh ordo Diptera., Insects are among the most significant numbers of living things in the world that have many benefits. However, there are still many insects that have not been identified yet, for example, insects in mangrove ecosystems. Each age of the stand has differences in vegetation structure, so insect diversity research on each age difference of R. mucronata is essential. Sampling was collected by purposive sampling by taking three guludan samples measuring 5 m  10 m. In each sample, a census was carried out to measure the diameter and height of R. mucronata at the age of 17, 13, 9, and 4 years for further vegetation analysis. The capture of insects is carried out using a yellow-pan trap and then identified to the level of morphospecies. The results showed a relationship between the age of different stands. At a young age had a lot of diversity and the highest value of insect abundance. The age of R. mucronata 13 years had the highest quantity dominated by the order Diptera.
Keyword: ekosistem, kerapatan, morfospesies, suhu, yellow-pan trap

Judul: Biodiversitas  Serangga pada Perkebunan Jeruk Pamelo (Citrus maxima (Burm.) Merr.) di Desa  Bageng, Kecamatan Gembong, Kabupaten Pati
Abstrak: Serangga memiliki keanekaragaman yang sangat tinggi dan kemampuan adaptasi yang baik pada berbagai habitat. Kajian mengenai serangga pada perkebunan jeruk pamelo di Indonesia belum banyak dilaporkan. Penelitian ini bertujuan menganalisis keanekaragaman serangga dengan tiga metode koleksi berupa insect net, yellow pan trap, dan Malaise trap pada perkebunan jeruk pamelo di Pati, Jawa Tengah. Pengamatan keanekaragaman serangga dilakukan dengan metode scan sampling dengan mencatat nama spesies dan jumlah individu serangga. Koleksi serangga juga dilakukan dengan menggunakan yellow pan trap dan Malaise trap. Serangga yang dikumpulkan berjumlah 4506 individu yang terdiri atas 128 spesies (morfospesies) dalam 52 famili. Serangga yang ditemukan terbanyak termasuk dalam ordo Hymenoptera, famili Formicidae. Jumlah individu dan spesies serangga paling banyak didapatkan dengan Malaise trap (2349 individu, 77 morfospesies). Diversitas serangga di perkebunan jeruk pamelo termasuk tinggi (Hʹ=3,16, E=0,18) dengan indeks dominansi sebesar 0,15. Salah satu spesies serangga yang banyak ditemukan adalah Anoplolepis gracilipes. Jumlah individu serangga memiliki korelasi positif terhadap suhu, kelembapan udara, dan intensitas cahaya., Insects have a very high diversity and good adaptability in various habitats. Studies on insects in pummelo plantations in Indonesia have not been widely reported. This study aims to analyze the diversity of insects using three collection methods, insect net, yellow pan trap, and Malaise trap in pummelo citrus plantations in Pati, Central Java. Observation of the diversity of insects was carried out using the scan sampling method by recording the name of species and the number of individual insects. Insect collection was also carried out using yellow pan trap and Malaise trap. The collected insects totally 4506 individuals consisting of 128 species (morphospecies) belonging to 52 families. Most insects are included in the Hymenoptera order, family Formicidae. The highest number of individuals and insect species was collected by Malaise traps (2349 individuals, 77 morphospecies). Insect diversity in pummelo plantations was high (Hʹ=3.16, E=0.18) with a dominance index of 0.15. One species of insect that is commonly found is Anoplolepis gracilipes. The number of individual insects has a positive correlation with temperature, humidity, and light intensity
Keyword: insect net, Malaise trap, scan sampling, yellow pan trap

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: