Judul: Autekologi dan studi populasi Myristica teijsmannii Miq.  (Myristicaceae) di Cagar Alam Pulau Sempu, Jawa Timur
Abstrak: Myristicaceae merupakan famili khas tropis dengan Myristica sebagai genus terbesar. Di antara 175 spesies Myristica di dunia 9 spesies merupakan spesies asli Indonesia bahkan beberapa termasuk endemik, langka dan dilindungi undang-undang. Myristica teijsmannii Miq. atau dikenal dengan nama Durenan, Palan, Kosar atau Kayu Resep merupakan salah satu spesies yang termasuk ke dalam kategori endangered atau genting menurut IUCN dengan kriteria EN B1+2C. Spesies ini memiliki penyebaran jarang dan baru dilaporkan ditemukan di Jawa Timur, yaitu di kawasan Pacitan - Gunung Kawi, Gunung Wilis, Gunung Anjasmoro dan Pulau Sempu. Data kuantitatif status populasi serta aspek-aspek ekologis, kebutuhan dan interaksi ekologis M. teijsmannii dengan habitatnya (autekologi) belum diketahui. Berdasarkan hal tersebut, maka penelitian ini dilakukan untuk mempelajari populasi, karakteristik habitat, interaksi dan kebutuhan-kebutuhan ekologis M. teijsmannii dengan memfokuskan penelitian di Pulau Sempu yang berstatus sebagai cagar alam. Studi ini dilakukan di enam lokasi yang secara estimasi visual mewakili keragaman floristik dan kondisi lingkungan Cagar Alam, yaitu Telaga Lele, Telaga Sat, Teluk Semut, Air Tawar, Gua Macan, dan Waru-waru.
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Judul: Keanekaragaman dan Pola Sebaran Spesies Tumbuhan Asing Invasif di Cagar Alam Pulau Sempu, Jawa Timur
Abstrak: The presence of invasive alien plant species has been known to cause various negative impacts on ecosystems in the invaded conservation area. This research aims to identify the diversity and distribution pattern of invasive alien plants species occurred in Sempu Island Nature Reserve, and to determine the most influential environmental factors to their dispersion. The methods used were the standard vegetation analysis and rapid assessment technique. According to the results, as many as 10 invasive alien plants species (belonging to 7 families) have been identified to occurred in this conservation area, e.g., Pistia stratoites, Ageratum mexicanum, Vernonia cinerea, Cyperus rotundus, Passiflora foetida, Centotheca lappacea, Eleusine indica, Imperata cylindrica, Hedyotis corymbosa, and Lantana camara. All invasive alien plant species found in the sampling plots had a clumped distribution pattern. The most influential environmental factors to the invasive alien plants dispersion were land slope and distance from shoreline.
Keyword: Sempu Island Nature Reserve, invasive alien plants, environmental factors, distribution pattern

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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