Judul: Sistem Dinamik Model Pengurangan Biomassa Hutan Akibat Penumpukan Industrialisasi
Abstrak: Forests are lungs of the earth which regulate ecological stability and it is important in cycles of oxygen (O2) and carbon dioxide (CO2). Forests give many benefits for supporting human life. The sustainability of forests for life of human are determined by consciousness of society in using them. Uncontrolled exploitations have effects for depletion of forest biomass. In this research, we present a nonlinear mathematical model, which has been analyzed to study the depletion of forest biomass. Moreover, this research also considers the implication of crowding by industrialization on forest biomass. A mathematical model is formulated to investigate the depletion of forest biomass. There are four variabels to consider, namely, the density of forest biomass (��), population of human (��), population pressure (��), and density of industrialization (��). In this research, we get four nonnegative equilibria, namely, ��1, ��2, ��3, and ��4. The equilibria ��1, ��2, and ��3 are analyzed by linierizing the system. Then, we determine the eigenvalues of the Jacobian matrix for those equilibria. The equilibrium ��4 is analyzed by use stability theory of Liapunov. The analysis of the model showed that under certain condition, ��1, ��2, and ��3 are unstable saddle point. Whereas the equilibrium ��4 is globaly asymtotically stable. The numerical simulations show that the equilibrium level of forest biomass density decrease as the equilibrium level of the human population, population pressure, and density of industrialization increase. It is lower than its original carrying capacity. Moreover, if the rate of crowding by industrialization increases, then the forest biomass density decreases. In all simulations, we conclude that if conditions of stability theorems are satisfied, then dynamics of the system always attain their corresponding equilibrium level.
Keyword: dynamical system, forest biomass, industrialization, stability

Judul: Model Simulasi Pengaturan Hasil Hutan Kayu pada Hutan Alam PT Suka Jaya Makmur Provinsi Kalimantan Barat
Abstrak: Sustainable forest management is done to achieve sustainable forest in terms of economic, ecological, and social. Information about the dynamics of stand structure and yield regulation methods is required for estimating stand structures in the future and yield regulation methods that can be applied in a virgin area. The purpose of this research is to gain sustainable yield regulations model and information on company income and forest communities from some scenarios. The dynamics of stand structure were obtained by calculating ingrowth, upgrowth, mortality, and basal area. The application of this yield regulation method considered the number of trees available in a forest area and rotation and logging intensity used. Simulations are carried out by two methods which are the conventional yield regulation methods and the adaptive yield regulation methods. The simulation results were showed the greater intensity of logging, the larger trees would be cut down and the longer rotation would be achieved. Furthermore, the market price and the number of trees affected the logging is done
Keyword: Bogor Agricultural University (IPB), yield., rotation, number of trees, intensity, dynamics

Judul: Penggunaan Trypan Blue pada Evaluasi Spermatozoa Kucing Asal Cauda Epididymis dan Ductus Deferens setelah Penyimpanan pada Suhu 4OC.
Abstrak: Pada penelitian ini digunakan Trypan Blue untuk evaluasi spermatozoa kucing sebagai kontrol digunakan pewarna Eosin-Nigrosin. Evaluasi dilakukan untuk mengetahui viabilitas dan abnormalitas spermatozoa yang dikoleksi dari cauda epididymis dan ductus deferens setelah penyimpanan jaringan pada suhu 4°C. Pada penelitian ini digunakan jaringan epididyrnis dan ductus deferens dari 21 ekor kucing jantan yang telah dikastrasi.
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