Judul: Pendekatan Matematis pada Pembangkitan Gelombang Internal di Selat Makassar
Abstrak: Di selat Makassar, yang terletak di antara pulau Kalimantan dan Sulawesi, fenomena gelombang internal yang menakjubkan dapat diamati. Gelombang internal adalah gelombang gravitasi yang berosilasi di dalam, bukan di permukaan, media fluida. Gelombang internal terjadi di bagian dalam air di laut, yang terjadi karena perbedaan densitas lapisan bawah dan atas fluida. Karakteristik khas gelombang internal adalah panjang gelombang dan amplitudonya yang besar. Penelitian ini bertujuan untuk mendapatkan hubungan dispersi berdasarkan persamaan dasar fluida dua lapis, menentukan gelombang internal di Selat Makassar, dan membuat simulasi pembangkitan gelombang internal menggunakan perangkat lunak Mathematica. Hasil penelitian menunjukkan bahwa mekanisme pembangkitan gelombang internal ini dapat dirumuskan berdasarkan hubungan dispersi Kelvin-Helmholtz untuk fluida dua lapis. Relasi dispersi ini juga dapat digunakan sebagai kriteria klasifikasi ketidakstabilan gelombang internal. Penekanan diberikan pada jenis ketidakstabilan, yaitu ketidakstabilan temporal dan spasial. Stabilitas temporal terjadi jika kecepatan arus di bagian atas fluida kurang dari kecepatan kritisnya. Untuk ketidakstabilan spasial, gelombang internal di Selat Makassar dapat didekati untuk kedua lapisan sebagai gelombang laut dalam. Daerah stabil spasial tercapai ketika frekuensi bagian bawah fluida lebih kecil dari frekuensi kritis, atau ketika frekuensi bagian atas fluida lebih besar dari frekuensi kritis.
Keyword: Makassar strait, generation of internal waves, instability

Judul: Pendekatan matematis pada pembangkitan gelombang internal di Selat Makassar
Abstrak: In Makassar strait, which is located between the islands of Kalimantan and Sulawesi, the fascinating phenomena of internal waves can be observed. Internal waves are gravity waves that oscillate within, rather than on the surface of, a fluid medium. Internal waves occur in the interior of water in seas, which exist due to a difference in density of the lower and upper layer of the fluid. Typical characteristics of internal waves are their large wavelength and amplitude. This research aims to derive a dispersion relation based on the basic equations of two-layers fluid, to determine the internal waves in the Makassar Strait, and to create a simulation of generation of the internal waves using the software Mathematica. The results show that the generation mechanism of these internal waves can be formulated based on the Kelvin-Helmholtz dispersion relation for a two-layers fluid. This dispersion relation can also be used as classification criteria of instability of internal waves. Emphasis is given to the types of instability, i.e. temporal and spatial instability. Temporal stability occurs if current velocity in the upper part of fluid is less than its critical velocity. For the spatial instability, internal waves in Makassar strait can be approximated for both layers as deep water waves. The spatially stable region is reached when the frequency of the lower part of fluid is smaller than the critical frequency, or when the frequency of the upper part of fluid is larger than the critical frequency.
Keyword: Sea current, Generation of internal waves, Pycnocline

Judul: Onset, Durasi, dan Gejala Klinis Anestesi pada Kelinci New Zealand White (Oryctolagus cuniculus) dengan Kombinasi Ketamin-Xylazin Intramuskular
Abstrak: The aim of this research was to expound the onset, duration, and clinical signs observed on anaesthesia phase using ketamine-xylazine combination in New Zealand White rabbits. Fifteen New Zealand White rabbits (Oryctolagus cuniculus) were randomly subjected into three groups of five animals each. Those in group A were anaesthetized using a combination of 35 mg/kg ketamine and 5 mg/kg xylazine given i/m. Group B animals were anaesthetized using a combination of 40 mg/kg ketamine and 5 mg/kg xylazine while group C were anaesthetized using a combination of 45 mg/kg ketamine and 5 mg/kg xylazine, both given i/m. The result of this study indicated that the onset of anaesthesia marked by loss of pain response differ not significantly among the three groups (P < 0.05). Duration of anaesthesia and recovery significantly differ (P < 0.05) as the dose of ketamine increased. The onset of anaesthesia clinical signs within induction phase showed significant differences on sternal recumbency, lateral recumbency, and constricted pupil. Meanwhile the onset of anaesthesia clinical signs showed no significant differences (P<0.05) within recovery phase. It was concluded that onset of anaesthesia and clinical signs in induction phase were directly proportional as the ketamine’s dose increased. Meanwhile duration of anaesthesia and duration of recovery were inversely proportional with the dose increasing.
Keyword: anesthesia, ketamine-xylazine, New Zealand White, rabbit