Judul: Perbandingan Preferensi Beruk (Macaca nemestrina) Usia Muda terhadap Perangkat Pengayaan Lingkungan di Pusat Studi Satwa Primata IPB
Abstrak: Beruk (Macaca nemestrina) adalah satwa primata endemis Indonesia dan digunakan sebagai salah satu hewan model dalam penelitian. Pemanfaatan beruk dalam dunia biomedis harus mengacu pada prinsip kesejahteraan hewan. Pemeliharaan beruk pada penangkaran ex situ atau fasilitas buatan berpotensi memengaruhi perilakunya menjadi abnormal, sehingga pengayaan lingkungan penting untuk mempertahankan perilaku alaminya. Penelitian ini bertujuan mengetahui respon beruk terhadap pemberian objek baru yang dapat dijadikan sarana pengayaan lingkungan yang memperkaya aktivitas satwa sehari-hari. Penelitian ini menggunakan tujuh ekor beruk berkoloni usia 1 – 2 tahun. Pengamatan perilaku dilakukan saat pemberian perangkat pengayaan lingkungan berupa puzzle ball dan rumput sintetis sebagai sarana pemberian sayuran. Perilaku yang diamati adalah eating, exploring, foraging, socializing, aggressiveness, fighting, playing, dan inactive. Berdasarkan studi ini dapat disimpulkan bahwa pengamatan perilaku Macaca nemestrina di Pusat Studi Satwa Primata IPB yang diberikan perangkat pengayaan lingkungan berupa puzzle ball dan rumput sintetis menunjukkan perilaku yang didominasi perilaku eating, exploring, dan foraging. Pemberian perangkat pengayaan akan mendorong sifat alamiahnya pada beruk, khususnya perilaku foraging dan exploring. Sementara, perilaku yang teramati tanpa pemberian perangkat pengayaan didominasi perilaku inactive dan playing., Pigtail macaque (Macaca nemestrina) is an endemic primate of Indonesia and is used as one of the model animals in research. The use of macaques in the biomedical world must refer to the principles of animal welfare. The maintenance of macaques in ex situ captivity or artificial facilities has the potential to influence their behavior to become abnormal, so environmental enrichment is important to maintain their natural behavior. The purpose of this research is to determine the ape's response to giving new objects that can be used as a means of enriching the environment that enriches the daily activities of animals. This study used seven macaques in colonies aged 1 – 2 years. Behavioral observations were made when giving environmental enrichment in the form of puzzle balls and synthetic grass as a means of giving vegetables. The observed behaviors were eating, exploring, foraging, socializing, aggressiveness, fighting, playing and silent. Based on this study, it can be concluded that observations of the behavior of Macaca nemestrina at the Primate Research Center of IPB University, which were given environmental enrichment, showed behavior that was dominated by eating, exploring, and foraging behavior. The provision of enrichment will encourage their natural properties in macaques, especially foraging and exploring behavior. Meanwhile, the observed behavior without the provision of enrichment was dominated by silent and playing behavior.
Keyword: perilaku, kesejahteraan hewan, foraging, exploring

Judul: Preference Study Of Old Pigtail Macaques (Macaca nemestrina) Towards New Environtmental Enrichment in Primate Research Center IPB
Abstrak: Beruk or pigtail macaques (Macaca nemestrina) is one of the Indonesian nonhuman primates that has an important role in biomedical research. Fulfilling animal welfare for macaques in research and captive facilities is an important thing that must be implemented. This study aims to examine the preferences or interests of the pigtail macaques for environmental enrichment in the form of provision of vegetables, tubers and fruits based on the behavior patterns and activities of five macaques in colonies kept at the research animal facility of the Primate Research Center of IPB. Behavioral observation was carried out using the scan animal sampling method on eating, inactive, foraging, object manipulation, fighting, aggressive behavior, social interaction, abnormal behavior, and others. The results showed that pigtail macaques had an interest when provided long beans, kale, sweet potatoes smeared with honey, and watermelon which were given in agar. This is characterized by the dominance of eating and foraging behaviors shown during the period of environmental enrichment provision. Based on the duration of feeding, foraging and object manipulation activities, the order of the monkeys' interest in environmental enrichment objects from high to low consists of sweet potatoes smeared with honey, long beans, watermelon in agar, and water spinach. Keywords: Animal welfare, environmental enrichment, macaca nemestrina, preference, scan animal sampling.
Keyword: animal welfare, environtmental enrichment, Macaca nemestrina, Preference, Scan animal sampling

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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