Judul: Gambaran histologis alat gerak dan kadar kalsium tulang Tikus setelah pemberian ekstrak Pegagan (Centella asiatica)
Abstrak: Tujuan dari penelitian ini untuk mengetahui gambaran histologis alat gerak (tulang dan otot) setelah pemberian ekstrak pegagan (Centella asiatica). Sampel penelitian terdiri dari 16 sampel tulang dan otot yang telah diberi perlakuan ekstrak pegagan dosis 0 (kontrol), 100, 300, dan 600 mg/kgBB. Preparat histologis tulang dan otot masing-masing dibuat serta dievaluasi dengan mikroskop cahaya. Kadar kalsium tulang diukur dari hasil pengabuan basah dan dianalisa menggunakan Atomic Absorption Spectrophotometer (AAS). Berdasarkan pengamatan histologis tulang secara umum ditemukan perubahan gambaran pada daerah spongiosa dan tidak ada perubahan pada kompakta. Hal ini sesuai dengan hasil analisis kalsium tulang yang tidak menunjukkan perbedaan yang nyata antara kontrol dengan perlakuan. Pengamatan pada otot menunjukkan adanya peningkatan jumlah fasikulus yang tidak berbeda nyata dan peningkatan serabut otot yang berbeda nyata seiring dengan peningkatan dosis ekstrak pegagan. Peningkatan jumlah serabut otot ini menyebabkan ukuran otot semakin kecil. Dengan demikian, dapat dikatakan bahwa struktur mikroskopis tulang tidak dipengaruhi secara nyata oleh pemberian ekstrak pegagan per oral. Sementara itu, jumlah serabut otot dapat ditingkatkan secara nyata dengan pemberian ekstrak pegagan tersebut.
Keyword: Bone, Calcium level, Centella asiatica, Fasiculus, Muscle fibers, Bogor Agricultural University, Institut Pertanian Bogor, IPB

Judul: Gambaran histologis sel spermatogenik pada tikus setelah pemberian ekstrak pegagan (Centella asiatica)
Abstrak: Pegagan (Centella asiatica) is a medicinal plant that is widely used as a brain tonic but not yet known its effects on the male reproductive organs. The purpose of this study was to determine the histological appereance of spermatogenesis stages that found in testes and density of spermatozoa in the epididymis after giving a pegagan extract. This study using 16 rats that were divide into 4 treatment groups. Each treatment is given pegagan extract in different dose (0 mg/kg body weight (bw) as a control, 100 mg/kg bw, 300 mg/kg bw, and 600 mg/kg bw) orally for 8 weeks. The results showed that each pegagan extract treatment generally decreased spermatogenic cell number and density of spermatozoa in the epididymis. The percentage number of spermatogenic cells reduction in parallel to the increasing level of extract doses. The number of spermatogenic cells and density of spermatozoa in the epididymis can be reduced by giving of pegagan extract.
Keyword: Centella asiatica, histological, pegagan, spermatogenesis

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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