Judul: Morphology of Pollen Collected by Honey Bee Apis cerana and Apis nigrocincta in Central Sulawesi
Abstrak: Keanekaragaman tumbuhan sumber polen dapat mendukung konservasi lebah. Namun, informasi tumbuhan sumber polen lebah Apis cerana dan Apis nigrocincta di Sulawesi belum dilaporkan. Penelitian ini bertujuan mengidentifikasi tumbuhan (berdasarkan morfologi polen) dan mengelompokkan tipe polen ke dalam kategori nilai pentingnya sebagai sumber pakan A. cerana dan A. nigrocincta di Sulawesi Tengah. Metode penelitian meliputi pengamatan warna bee pollen, preparasi polen dengan asetolisis, pengamatan morfologi dan identifikasi tipe polen, serta pengelompokkan tipe polen ke dalam kategori nilai penting. Hasil penelitian menunjukkan preferensi A. cerana terhadap sumber polen yang lebih beragam (16 tipe polen) dibandingkan A. nigrocincta (satu tipe polen). Cocos nucifera merupakan sumber polen predominant bagi A. cerana dan A. nigrocincta. Polen dari lima spesies tumbuhan lainnya dan polen gramineae termasuk dalam kategori important minor bagi A. cerana, sedangkan polen dari sembilan spesies tumbuhan lainnya termasuk kategori minor. Sebagian besar sampel bee pollen dari A. cerana dan A. nigrocincta berwarna dark yellow, dan bee pollen dengan warna sama dapat memiliki tipe polen predominant dari spesies tumbuhan berbeda. Tumbuhan sumber polen A. cerana berhabitus pohon, semak, dan herba; sedangkan sumber polen A. nigrocincta hanya dari tumbuhan berhabitus pohon., Diversity of pollen sources plants could supported bee conservation. However, the information on pollen source plants for Apis cerana and Apis nigrocincta in Sulawesi has not been reported. This study aimed to identify the plants (based on the pollen morphology) and to group pollen type into the important value categories as food sources for A. cerana and A. nigrocincta. The methods were used observing bee pollen color, identifiying pollen type based on the morphological characters, and grouping the pollen type into its importance categories. The results showed A. cerana has more differs preference on food sources (16 pollen types) compared to A. nigrocincta (one pollen type). Cocos nucifera was the predominant pollen sources for both A. cerana and A. nigrocincta. The gramineae pollen and five other pollen types were included in important minor category for A. cerana, while nine other pollen type were in the minor category. Most of the bee pollen collected from A. cerana and A. nigrocincta was dark yellow. Bee pollens have similar color might have different predominant pollen type. The pollen sources plants of A. cerana were trees, shrubs, and herbs, but only trees for A. nigrocincta.
Keyword: Apis nigrocincta, bee forage plants, important minor pollen, predominant pollen, Sulawesi

Judul: The Activity of Apis cerana Honey Bee and the Potencial of Food Resources at Surouding Hive Area in Mekarjaya, Pandeglang
Abstrak: Informasi mengenai aktivitas mencari pakan (foraging) dan jenis tanaman sumber pakan penting untuk usaha peningkatan produktivitas lebah madu Apis cerana. Penelitian ini bertujuan menganalisis: (1) pola aktivitas harian lebah A.cerana yang dipengaruhi oleh faktor lingkungan, dan (2) keanekaragaman tanaman sumber polen di sekitar sarang lebah di Desa Mekarjaya, Kabupaten Pandeglang, Banten. Penelitian ini menggunakan dua koloni A. cerana yaitu koloni satu dan koloni dua dengan ukuran koloni yang sama. Perilaku yang diamati yaitu lebah keluar sarang, masuk membawa polen, dan masuk tanpapolen. Hasil pengamatan menunjukkan puncak aktivitas foraging koloni satupada pukul 07.40-08.50 WIB sedangkan koloni dua menunjukan aktivitas foraging yang rendah. Koloni dua melakukan absconding yang terjadi pukul 14.35- 16.30.Rendahnya aktivitas foraging pada koloni dua merupakan sinyal bahwa lebah akan melakukan absconding atau bermigrasi meninggalkan sarang. Hasil analisis vegetasi menunjukkan bahwa tanaman di sekitar sarang merupakan tanaman penghasil polen, nektar, atau polen dan nektar, didominasi oleh Cocos nucifera yang berpotensis menghasilkan polen dan nektar. Indeks keanekaragaman spesies tumbuhan menunjukkan bahwa keanekaragaman tanaman di area tersebut dikategorikan stabil. Hasil analisis jumlah spesies menunjukan bahwa jumlahspesies bernilai mendekati satu, sehingga dikategorikan jumlahnya relatif sama dalam berbagai tegakan., The information on honey bee foraging activities and food sources are important to increase the productivity of Apis cerana. This study aimed to analyze: (1) the daily activity pattern of A. cerana bees that is affected by environmental factors and (2) the diversity of pollen source plants around the beehive at Mekarjaya Village, Pandeglang Regency, Banten. This study used two colonies of A. cerana. The observed behaviors were bees leaving the hive, entering carrying pollen, and entering without pollen. This result showed that the peak of foraging activity in colony one occurs at 07.40-08.50. Colony two showed a low foraging activity that is a signal of the absconding bees or bee migrated. The correlation values between environmental factors: temperature, humidity, and light intensity compared to the honey bee activity was range from 0 to 1. The results of the vegetation analysis showed that the plants around the hive were plants that produce pollen, nectar, or pollen and nectar and the dominant was Cocos nucifera. The plant species diversity index showed that the diversity of plants in the area was categorized as stable. The results of species number analysis were close to one, thus the numbers were categorized as relatively the same in the various stands.
Keyword: Apis cerana, absconding, foraging, nectar source, pollen

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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