Judul: Daily Activities and Forest Structure Usage by Langur Borneo in Lupak Mawang Resort Danau Sentarum National Park
Abstrak: Langur borneo merupakan primata endemik yang memiliki wilayah persebaran di Pulau Kalimantan dan masuk dalam kategori terancam punah dengan level kritis (critically endangered) menurut IUCN. Penelitian ini bertujuan untuk mengidentifikasi aktivitas harian langur dan mengidentifikasi penggunaan ruang oleh langur borneo. Penelitian dilaksanakan pada bulan Juli - Agustus 2021 yang berlokasi di Bukit Semujan, Resort Lupak Mawang – TN Danau Sentarum. Aktivitas harian diamati dengan menggunakan metode scan sampling sedangkan pola penggunaan ruang diidentifikasi dengan analisis vegetasi. Hasil penelitian menunjukkan aktivitas harian yang memiliki persentase terbesar berdasarkan pembagian waktu dan frekuensi perjumpaan yaitu aktivitas sosial yang dilakukan pada sore hari dengan persentase sebesar 73.68% dan 72.22%. Strata C dengan ketinggian 4-20 m dengan persentase sebesar 70.49% merupakan kategori strata yang paling sering digunakan oleh Langur borneo dalam melakukan seluruh aktivitasnya. Hasil analisis vegetasi di hutan primer dan sekunder menunjukkan bahwa pohon tekam padi (Polyalthia insignis) dan pohon kelangsau (Dryobalanops lanceolata) mempunyai indeks nilai penting tertinggi yaitu masing-masing sebesar 50.00% dan 115.05%., Langur borneo is an endemic species that occurred only in Kalimantan and is categorized by the IUCN as a critically endangered species. This research aim is to identify the daily activities and forest structure usage by langur borneo. This research was conducted from July to August 2021 at Bukit Semujan, Lupak Mawang Resort, Danau Sentarum National Park. The daily activities were observed using the scan sampling method, meanwhile for forest structure usage were using vegetation analysis. Results show that daily activities with the largest percentage based on time usage and frequency are the social activity which was carried out in the afternoon with each percentage of 73,68% and 72,22%. Strata C (4-20 meters) with a percentage of 70.49% be the most often used strata category by Langur borneo to carry out their activities. Result of the vegetation analysis in primary and secondary forest respectively shows that tekam padi (Polyathia insignis) and Kelangsau (Dryobalanops lanceolata) trees had the highest important value index, with each percentage of 50.003% and 115.04%.
Keyword: daily activities, forest structure use, langur borneo

Judul: Habitat Characteristics and Feed Preferences of Bornean Langur (Presbytis chrysomelas ssp. cruciger Thomas 1892) at the Lupak Mawang Resort, Danau Sentarum National Park
Abstrak: Langur borneo adalah primata endemik pulau Kalimantan dikategorikan terancam punah (critically endangered) oleh IUCN. Tujuan dari penelitian ini adalah untuk mengidentifikasi karakteristik habitat, mengidentifikasi jenis dan preferensi pakan, serta menganalisis ketersediaan pakan langur borneo. Penelitian dilaksanakan di Resort Lupak Mawang, Taman Nasional Danau Sentarum pada bulan Juli hingga Agustus 2021. Metode pengambilan data yang digunakan yaitu pengamatan langsung dan wawancara, sedangkan metode analisis data menggunakan vegetasi untuk menganalisis dan mendeskripsikan karakteristik habitat. Hasil pengamatan menunjukan bahwa langur borneo menempati wilayah dengan ketinggian 32-257 mdpl dan kemiringan lahan 24%-45%. Aktivitas harian langur borneo lebih sering dilakukan pada strata tajuk C (4-18) m di hutan primer dan campuran. Aktivitasnya dimulai pukul 05.00 hingga 17.30 yang ditandai dengan vokalisasi. Langur borneo mengkonsumsi 27 jenis tumbuhan dari 16 famili. Persentase bagian tumbuhan yang dimakan langur borneo yaitu daun 50%, buah 30%, dan biji 20%. Langur borneo memiliki preferensi terhadap buah gita susu (Willunghbeia coriacea) yang berhabitus liana dengan persentase 36%., Bornean langur is a primate endemic to Borneo is categorized as critically endangered by the IUCN Red List. Information on the population condition and habitat of the bornean langur in Indonesia is still limited. The research was carried out at the Lupak Mawang Resort, Danau Sentarum National Park from July to August 2021. The data collection methods used were direct observation and interviews. The vegetation analysis method was used to describe its habitat characteristics. The observations shows that the bornean langur occupies an area altitude of 32 – 257 meters above sea level and a land slope of 24%–45%. The daily activities of the bornean langur are more often carried out in the C canopy strata of (4-18 m) in primary dan mixed forest. The activity starts at 05.00 until 17.30 which is marked by vocalization. The bornean langur consumed 27 species of plants from 16 families. The plant parts percentage eaten by the bornean langur are 50% leaves, 30% fruit, and 20% seeds. Bornean langur has a preference for gita milk fruit (Willunghbeia coriacea) as liana habitus plant with a percentage of 36%.
Keyword: Langur borneo, Jenis tumbuhan pakan, Karakteristik habitat

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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