Judul: Reliability of Sonic Tomography Technology as Detector of Gaharu in Aquilaria microcarpa Baill
Abstrak: Gaharu or agarwood is known as valuable products of non timber forest products (NTFP’s). Due to its economic value, the product has been subjected to over exploitation practice in Indonesia's natural forests. Therefore, some gaharu producing trees have been classified as endangered species and included into Appendix II of CITES (convention on international trade for endangered species). Traditional harvesting practice of gaharu has been insisted to fell the trees without any reliable techniques in predicting the presence of gaharu. A study was conducted to evaluate the reliability of sonic tomography technology (Picus® Sonic Tomography) in detecting the presence of gaharu within A. microcarpa trees. Thirty five of A. microcarpa with ≥ 15 cm diameter at an experimental forest area in Carita, Banten Province were selected as sample trees. Four to six transducers of Picus® Sonic Tomography were mounted circularly on the stem of sample trees at 20 cm, 130 cm, and 200 cm height from the ground (as measuring points). The transducers were connected to the software system which could record any sonic wave velocities data of each sample trees, then converted those data to be color gradation images. The result showed that sonic wave velocities within sample trees were ranged from 400 to 900 m.s-1 with average value of 700 m.s-1. There was no significant difference of sonic wave velocity among measuring points. It was also found that sample trees with high sonic velocity tend to reveal dark color of tomography image (dark brown), meanwhile the lower value of sonic velocity denoted light color (green-violet-blue). In addition as such, gaharu containing sample trees tend to reveal light color image (sonic wave velocity around 750 m.s-1), low moisture content and high density. These findings were then proven by visual observation on the felled sample tree. In concluding, sonic tomography technology shows sufficient reliability to detect the presence of gaharu in the tree.
Keyword: Agarwood, Aquilaria microcarpa, sonic tomography, sonic wave velocity

Judul: Pendugaan Keberadaan Gaharu Pada Berbagai Ketinggian Batang Aquilaria Malaccensis Lamk. Dengan Teknik Sonik Tomografi
Abstrak: Gaharu merupakan salah satu hasil hutan bukan kayu (HHBK) yang memiliki nilai ekonomi tinggi, terbentuk di dalam batang atau cabang beberapa jenis pohon seperti Aquilaria malaccensis Lamk. Pembentukan bongkahan resin berwarna coklat dan beraroma harum tersebut terjadi sebagai respon pohon terhadap infeksi fungi tertentu ke dalam batang atau cabang pohon baik secara alami maupun sengaja diinokulasi. Secara tradisional, deteksi keberadaan gaharu di dalam batang pohon A. malaccensis dilakukan dengan cara melukai permukaan batang pohon tersebut, bahkan menebangnya tanpa kepastian keberadaan produk hayati tersebut. Oleh karena itu diperlukan inovasi teknologi yang dapat menduga keberadaan gaharu di dalam batang pohon A. malaccensis tanpa merusak batang pohon tersebut. Suatu penelitian telah dilakukan untuk menduga keberadaan gaharu pada batang pohon A. malaccensis menggunakan alat PiCUS® Sonic Tomograph. Pengukuran kecepatan rambat bunyi dilakukan pada lima batang pohon contoh yang diinokulasi fungi dan lima batang pohon contoh tanpa inokulasi fungi, masing-masing pada ketinggian 20 cm, 70 cm, 120 cm, 170 cm, 220 cm dan 270 cm dari permukaan tanah. Data kecepatan rambat gelombang bunyi dan tomogram pada masing-masing ketinggian tersebut kemudian dibandingkan dengan kondisi faktual bagian dalam batang pohon contoh pada ketinggian yang sama pasca penebangan. Hasil penelitian menunjukkan bahwa kecepatan rambat gelombang bunyi pada berbagai ketinggian titik pengukuran baik pada batang pohon tanpa inokulasi maupun pada batang pohon yang diinokulasi fungi tidak berbeda nyata. Kecepatan rambat gelombang bunyi juga tidak berbeda nyata antara pohon yang diinokulasi fungi dan pohon tanpa inokulasi fungi. Kecepatan rambat gelombang bunyi pada lempengan batang pohon pasca penebangan (kondisi kering udara) 1.10 kali lebih tinggi dibandingkan pada batang pohon yang masih berdiri (kondisi basah). Bagian kayu bergaharu pada batang pohon A. malaccensis yang diinokulasi fungi lebih besar dibandingkan pada batang pohon tanpa inokulasi fungi. Tomogram yang dihasilkan dari alat PiCUS® Sonic Tomograph mampu mendeteksi keberadaan gaharu pada batang pohon A. malaccensis dengan tingkat akurasi 80-90%. Rerata volume gaharu yang dihasilkan pohon A. malaccensis adalah ±3.8% dari volume total batang pohon dengan kualitas tergolong sedang.
Keyword: citra tomogram, gaharu, gelombang bunyi, PiCUS® Sonic Tomograph

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model