Judul: Aktivitas Makan dan Preferensi Pakan Orangutan Sumatera (Pongo abelii Lesson, 1827) di Resort Bukit Lawang, Taman Nasional Gunung Leuser
Abstrak: Orangutans are one of the primates which known as great apes and it is endemic in the island of Sumatera. This research was done at Sumatran Orangutan Viewing Center in Bukit Lawang. The aim of this study is to know the feed preferences and feeding activities of sumatran orangutan. The methods used in this study are Focal Animal Sampling which is done by following one individual orangutans during a certain period and single swath method in three different plots. The observations showed that orangutan’s feeding activity are smaller than resting and moving activity. There are 47 kinds of food that was eaten by orangutans. This food consisting of 5 habitus that is a tree, liana, herbaceous, clumps, and epiphyte. The part of plants that mostly consumed are leaves as much as 48,61%, fruit 27,49%, others (termites, ants, insects, soil) 12,75%, bark 7,17%, and flower 3,98%. Based on the feed preferences, the preferred type of feed are sibolangit (Garcinia lateriflora), rattan (Calamus sp.), and rambung (Vernonia arborea).
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Judul: Potential and Feed Preferences for Sumatran Orangutans at the Gunung Leuser National Park
Abstrak: Orangutan sumatera (Pongo abelii, Lesson 1827 ) adalah salah satu spesies primata yang keberadaannya di dunia terancam punah, sehingga perlu upaya melestarikannya melalui pengelolaan tumbuhan pakannya di dalam habitatnya. Penelitian dilaksanakan di Stasiun Penelitian Ketambe (SPK) dan Kawasan ekowisata Lawe Gurah (KELG) dengan tujuan menduga dan mengidentifikasi jenis pakan, ketersediaan pakan dan preferensi pakan orangutan sumatera. Pakan orangutan dikategorikan menjadi sangat disukai, disukai, kurang disukai, dan tidak disukai menggunakan Indeks Preferensi Jacobs (Di). Terindentifikasi spesies pohon pakan yang termasuk dalam 31 spesies dari 15 famili di SPK dan 41 spesies yang tergolong kedalam 28 famili di KELG. Jenis pakan yang sangat disukai adalah Rambung (Ficus sp.) berupa buah, daun muda dan bunga (Di=0,86), durian (Durio zibhetinus) berupa buah dan daun muda (Di=0,63). Perilaku makan orangutan sumatera, berdasarkan aktivitas makan terlihat aktivitas makan sebesar 38,34% dari aktivitas hariannya, buah adalah pilihan yang sangat disukai dengan persentase 78,17%. Preferensial pakan juga berpengaruh terhadap proporsi makan dari orangutan dimana proporsi remaja jantan lebih proporsional daripada orangutan dewasa jantan dengan persentase 25% berbanding 16%., The Sumatran orangutan (Pongo abelii, Lesson 1827 ) is one of the primate species whose existence in the world is threatened with extinction, so efforts are needed to preserve it through the management of its forage plants in its habitat. The research was carried out at the Ketambe Research Station (SPK) and the Lawe Gurah Ecotourism Area (KELG) with the aim of predicting and identifying the type of feed, the availability of feed and the food preferences of the Sumatran orangutan. Orangutan feeds were categorized into highly favored, preferred, less preferred, and disliked using the Jacobs Preference Index (Di). The forage tree species were identified as belonging to 31 species from 15 families in SPK and 41 species belonging to 28 families in KELG. The type of feed that was highly preferred was Rambung (Ficus sp.) in the form of fruit, young leaves and flowers with (Di=0.86), durian (Durio zibhetinus) in the form of fruit and young leaves with (Di=0.63). The eating behavior of Sumatran orangutans, based on eating activities, it can be seen that eating activity is 38.34% of their daily activities, fruit is the most preferred choice with a percentage of 78.17%. Feed preference also affects the proportion of eating from orangutans where the proportion of male juveniles is more proportional than adult male orangutans with a percentage of 25% versus 16%.
Keyword: Ficus sp, Jacob's preference index, Lawe gurah ecotourism area, Pongo abelii lesson 1827, Feed preference, Ketambe research station

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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