Judul: Karakteristik Sifat Fisis dan Kecepatan Gelombang Ultrasonik Pohon Penghasil Gaharu Jenis Aquilaria microcarpa Baill.
Abstrak: As the increasement of its usefulness and demand, more people tried to get agarwood in any ways. Those can be lead threaten on its existence. By this condition, an innovation to detect agarwood inside the tree is necessary. The objective of this research was to know the physical properties and ultrasonic propagation characteristics of Aquilaria microcarpa Baill. The trees used in this research were 60 A. microcarpa with 3 different treatment condition, i.e trees without any infections as control, trees which infected by fungi for one time and infected three times. The testing were conducted by radial and longitudinal direction. Radial Testing were conducted to know the internal condition of the tree. Meanwhile, longitudinal testing were performed to predict the elasticity of the wood. Physical properties samples were taken from the bark to the core of the tree. Ultrasonic propagation testing in radial direction showed that its value at 20 cm, 130 cm and 200 cm of the tree height of the control trees were 969 m s-1, 915 m s-1 and 943 m s-1 respectively. For those height, ultrasonic propagation value at trees which infected for one time were 955 m s-1, 913 m s-1 and 911 m s-1respectively, meanwhile at the trees which infected for three times were 1008 m s-1, 928 m s-1 and 953 m s-1 respectively. At the longitudinal testing, the average values of ultrasonic propagation were 3366 m s-1, 3188 m s-1 dan 2817 m s-1 for control, one inoculation, and three inoculations trees, respectively. The dynamic modulus of elasticity (MOEd) value of the control trees, the trees which infected for one time and three times were 9.194 GPa, 8.498 GPa and 5.703 Gpa, respectively. Statistical analysis revelaed that the interaction between tree height measurement and treatments were not significantly influenced for ultrasonic velocity tested radially as well as single factor for both height measurement and treatments. Meanwhile, inoculation treatments were significant difference on ultrasonic velocity testing longitudinally and dynamic MOE. The average value of moisture content of the wood was 53.18%, while the density was 0.75 g cm-3.
Keyword: ultrasonic propagation, physical properties, Aquilaria microcarpa Baill, Agarwood

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: 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