Judul: The Effect of Different Light Colour of Lamp on  The Productivity of Earth Worms.
Abstrak: Cacing tanah adalah salah satu inevertebrata yang banyak terdistribusi di seluruh dunia, dan menyukai tanah lembab yang kaya akan bahan organik. Lumbricus rubellus adalah spesies cacing tanah yang bersifat nokturnal, dan aktif pada malam hari. Warna lampu memiliki efek pada tanaman dan hewan lainnya. Tujuan penelitian ini adalah untuk menganalisis produktivitas Lumbricus rubellus dibawah pengaruh warna cahaya yang berbeda. Penelitian ini menggunakan tiga warna lampu berbeda yaitu merah, kuning, dan biru, serta kontrol, dengan keadaan lingkungannya disimpan dalam keadaan gelap. Parameter yang di ukur adalah pertambahan bobot badan, jumlah segmen, jumlah kokon dan berat media akhir. Hasil dari penelitian ini menunjukan bahwa warna lampu berpengaruh nyata dengan nilai (P<0,05) terhadap pertambahan bobot badan, produksi kokon, dan jumlah segmen. Cacing tanah dibawah lampu merah memiliki pertambahan bobot badan (15,08 g), produksi kokon (11,99), dan jumlah segmen (30,01) yang paling tinggi dibandingkan perlakuan lainnya, sedangkan cacing tanah dibawah lampu warna kuning menunjukan penambahan bobot badan (2,00 g/minggu), produksi kokon (2,24), dan jumlah segmen (28,67) yang paling rendah, Earthworm is one of the invertebrates which is distributed around the world, and preferred moist soil that is rich in organic matter. Lumbricus rubellus is a species of an earthworm that have nocturnal trait, and become active at night. Light color has also an effect on plant, and other animals. The purpose of this research was to observe Lumbricus rubellus productivity under the effect of different light colours. This research uses three different colour of lights, red, yellow and blue colour, with control, where the environment is being keep completely in dark. The parameters oberserved are weight gain, number of segments, number of cocoons from Lumbricus rubellus, and final media weight. Results from this study shows that colour of light have a real effect with value of (P<0,05) on weight gain, cocoon production, and total segment. Earthworm under red light have the highest weight gain (15,08 g), cocoon production (11,99), and total segment (30,01) compared to other treatment, while earthworm under the yellow light shows the lowest weight ii gain (2,00 g/week), cocoon production (2,24), and total segment (28,67) compared to other treatment.
Keyword: light colours, Lumbricus rubellus, productivity

Judul: Performa Cacing Tanah (Lumbricus rubellus) Terhadap Warna Cahaya Lampu Yang Berbeda
Abstrak: Cacing tanah merupakan hewan invertebrata yang tersebar di seluruh dunia dan memiliki beragam manfaat. Salah satu jenis cacing tanah yang banyak dibudidayakan yaitu Lumbricus rubellus. Cacing ini merupakan hewan nokturnal yang bersifat fototaksis negartif. Warna cahaya lampu diduga berpengaruh terhadap performa cacing tanah. Penelitian ini bertujuan menganalisis performa Lumbricus rubellus dengan pengaruh warna cahaya lampu yang berbeda. Penelitian ini menggunakan tiga warna lampu yang berbeda yaitu jingga, hijau, ungu, serta gelap sebagai kontrol. Peubah yang diamati adalah pertambahan bobot, bobot media, jumlah segmen sampai klitelum, jumlah kokon, pH media dan jumlah populasi. Hasil penelitian menunjukkan bahwa ketiga jenis warna tidak dapat meningkatkan performa cacing tanah Lumbricus rubellus secara signifikan. Meskipun warna hijau dan ungu dapat meningkatkan pertambahan bobot badan namun nilainya masih lebih kecil daripada kondisi gelap., Earthworms are invertebrate animals that are spread throughout the world and have various benefits. One type of earthworm that is widely cultivated is Lumbricus rubellus. This worm is a nocturnal animal with negative phototaxis. The color of the lamp light is thought to have an effect on the performance of earthworms. This study aims to analyze the performance of Lumbricus rubellus with the influence of different light colors. This study used three different light colors, orange, green, purple, and dark as a control. The observed variables were weight gain, media weight, number of segments to the clitelum, number of cocoons, media pH and total population. The results showed that the three types of color did not significantly improve the performance of the earthworm Lumbricus rubellus. Although green and purple can increase body weight gain, the value is still smaller than the dark conditions.
Keyword: Light colours, Performance, Lumbricus rubellus

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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