Judul: Analysis of Spatio Temporal Dynamics Model in Malaria
Abstrak: Malaria is an infectious disease caused by protozoa of the genus Plasmodium, which is transmitted from person to another person through the bites of female Anopheles mosquitoes. Mathematical model can be used to study the spread of the disease. The mathematical model discussed in this paper is Ross- MacDonald model and models with spatial heterogeneity of migration model and visitation model. For the models of heterogeneous environments with mobility, we also made numerical simulations for different values of intensity connection between patches, values of e (the proportion of humans migrate) and T (visitation time). Stability analysis of Ross-MacDonald model give two stable equilibrium points. For the migration and visitation models, there are four stable equilibrium points. When in a fragmented environment, humans have a high migration rate between patches, the system will more rapidly reach the same equilibrium prevalence it reached with lower migration rates. When humans visit other patches, an increase in the time devoted to the visits will make the system reach a higher equilibrium prevalence more rapidly. The numerical simulation show that increasing mosquitoes mortality rate makes the number of infected humans being exposed decrease. If average bite of an infected mosquito increases, then the number of infected humans who become exposed also increases. For the mosquito population, increasing mosquitoes mortality rate will cause the number of infected mosquitoes being exposed decrease. Increasing the average bite of an infected mosquito will increase the number of infected mosquitoes that become exposed.
Keyword: 

Judul: Model Matematika Tipe SEIRS-SEI untuk Transmisi Penyakit Malaria
Abstrak: Malaria is an infectious disease caused by a parasite of the genus Plasmodium of Anopheles mosquito. The malaria is transmitted to human through mosquito bites which is very dangerous for our health. In this research, a system of ordinary differential equations for the spread of malaria in human and mosquito populations is presented. In the model formulated by Chitnis, the human population is divided into four classes, namely susceptible, exposed, infected, and recovered. The mosquito population is divided into three classes, namely susceptible, exposed, and infected. Susceptible human can be infected when they are bitten by infectious mosquitos. In this study, the exposed humans considered to have been open to be infected by parasites so they are classified into human exposed class. After a period of incubation elapsed, those in human exposed class might be infected so that they are classified into infected class. Those in infected class might be recovered after a latent period passed on so that they are classified into recovered class, or may return back to the susceptible class when the immunity decreased. Those in recovered class will have temporary immunity so that again be susceptible human in a given period. In this study, this model is a modification of a previous model is proposed and analyzed by adding a recovery rate of infected subclass into susceptible subclass of human. The simulation study showed the existence of two equilibrium points, i.e. the disease-free equilibrium and the endemic equilibrium points. Next, the stability analysis of the equilibrium points were conducted by considering the basic reproduction number ( ). The basic reproduction number is the expected value of infections per unit of time. The number is considered as a benchmark of disease transmission in the population. If then on average each infected individual will be infecting less than one newly individual, so that the disease will disappear. If , then on average each infected individual will generate more than one newly infected individuals, so that the disease will spread. Numerical analysis and simulation results showed that the number of each class of human and mosquito reaches a stable condition approaching the diseasefree equilibrium and obtained , and approaching the stable condition of the endemic equilibrium with the value of In addition, the increase of human recovery rate will decrease the . Therefore, the rate of disease transmission decreases. The human recovery rate indicates the proportion of infected human who get recovered of the disease and converted back into the susceptible subclass. Furthermore, it has been showen that for the human population, if the abovementioned recovery rates increase, then the number of susceptible human become exposed decrease. Similarly for the mosquito population, if the recovery rate increase, then the number of susceptible mosquitoes become exposed also decrease. As a consequence, disease will be vanished from population.
Keyword: mathematical models, malaria transmission, basic reproductive number, disease-free equilibrium, endemic equilibrium

Judul: Pembuatan papan semen dari sabut kelapa, Cocos nucifera L.
Abstrak: Di Indonesia, terutama di daerah sentra kelapa, tempurung dan sabut hanya digunakan sebagai bahan bakar, bahan kerajinan, dan sebagian kecil diolah menjadi arang. Menurut penelitian sebelumnya (Masri 1998), sabut kelapa memiliki potensi untuk digunakan sebagai bahan dasar papan semen, meskipun papan yang dihasilkan pada penelitian ini belum dapat memenuhi standar JIS A 5417 – 1992, terutama pada sifat mekanisnya. Penelitian ini bertujuan untuk mempelajari pengaruh penggunaan serat sabut kelapa sebagai bahan baku papan semen, serta pengaruh peningkatan taraf semen dan penambahan accelerator CaCl2 terhadap kualitas papan semen.
Keyword: