Judul: Manipulasi alat untuk mendapatkan ganjaran makanan di lar gibbons (Hylobates lar)
Abstrak: Tool manipulation in Hylobates lar has not been well documented in Malaysia. The main aim of this study is to assess whether lar gibbons are capable of manipulating objects to obtain a food reward. We assessed whether lar gibbons can learn to pull on a rake-like object to gain a food reward without specific training. The main task that is to be observed is the pulling of a rake-like rod to obtain a food reward with a time limit of 60 minutes. All the gibbons managed to obtain the reward at least once throughout the five trials. The gibbons are seen using a trial-error approach which proved to be successful in obtaining the reward. Female gibbons were also observed to be more cautious in attending to a new task or object compared to male gibbons. This can be seen when female gibbons made more interactions with tools prior successful trial compared to the male gibbons., Manipulasi alat di Hylobates lar belum didokumentasikan dengan baik di Malaysia. Tujuan utama dari penelitian ini adalah untuk menilai apakah owa lar mampu memanipulasi objek untuk mendapatkan ganjaran makanan. Kami menilai apakah owa lar dapat belajar menarik benda seperti penggaruk untuk mendapatkan ganjaran makanan tanpa pelatihan khusus. Tugas utama yang harus diamati adalah menarik garu seperti garu untuk mendapatkan ganjaran makanan dengan batas waktu 60 menit. Semua owa berhasil mendapatkan ganjaran setidaknya sekali selama lima percobaan. Owa terlihat menggunakan pendekatan trial-error yang terbukti berhasil mendapatkan ganjaran. Owa betina juga diamati lebih berhati-hati dalam mengerjakan tugas atau objek baru dibandingkan dengan owa jantan. Hal ini terlihat ketika owa betina lebih banyak berinteraksi dengan alat sebelum percobaan berhasil dibandingkan dengan owa jantan.
Keyword: food reward, gibbon, Hylobates lar, tool manipulation, ganjaran makanan, Hylobates lar, manipulasi alat, owa

Judul: The Effect of Different Types of Enrichment on Stereotypic Behaviour of Captive Hylobates lar at Gibbon Rehabilitation Project in Raub, Pahang, Malaysia
Abstrak: Owa serudung, juga dikenal sebagai Hylobates lar, sangat terancam punah. Rehabilitasi merupakan salah satu solusi untuk mencegah owa dari kepunahan. Untuk mengembalikan owa ke alam liar, owa harus siap secara fisik dan mental untuk kembali ke alam liar serta memenuhi tujuh kriteria pelepasan. Penelitian ini bertujuan untuk memahami penyebab, akibat, dan solusi perilaku stereotipik dan menyelidiki pengaruh empat perangkat pengayaan yang berbeda (pengayaan taktil, penciuman, makanan dan kognitif serta sosial) terhadap pengurangan perilaku stereotipik. Pengumpulan data dilakukan dengan metode observasi. Penataan dan analisis data dilakukan dengan menggunakan Statistical Package for Social Sciences for Windows (SPSS) dan Microsoft Excel. Hasil penelitian menunjukkan bahwa kehadiran manusia memicu terjadinya masturbasi dan demonstrasi posterior. Pemberian pengayaan membantu pengurangan perilaku stereotip. Dari empat perangkat pengayaan yang berbeda, owa serudung paling banyak berinteraksi dengan kain dan pisang (pengayaan taktil); namun, kotak penggali gantung lebih efektif dalam mengurangi perilaku stereotip meskipun owa paling sedikit tertarik padanya., White-handed gibbon, also known as Hylobates lar, are highly endangered and threatened with extinction. Rehabilitation is one of the solutions to prevent the gibbon from extinction. To reintroduce the gibbons into the wild, gibbons must be both physically and mentally ready to return to the wild as well as achieve seven criteria of release. This research aimed to understand the causes, effects and solutions to the stereotypic behaviour and investigate the effect of four different enrichment devices (tactile, olfactory, food and cognitive as well as social enrichment) on the reduction of stereotypic behaviour in one captive gibbon. The data were collected using the observation method. Data arrangement and analysis were done by using The Statistical Package for Social Sciences for Windows (SPSS) and Microsoft Excel. The result showed that the presence of humans triggers masturbation and posterior demonstration. The giving of enrichment helped the reduction of stereotypic behaviour . Of the four different enrichment devices, the gibbon interacted the most with the cloth and banana leaves (tactile enrichment); however, the hanging digging box was more effective in reducing the stereotypic behaviour even though the gibbon had the least interest on it.
Keyword: gibbon, stereotypic behaviour, enrichment, reduce, rehabilitation

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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