Judul: Kestabilan Model Oligopoli Cournot
Abstrak: untuk penyesuaian waktu diskret, setiap perusahaan berasumsi bahwa jumlah output yang dihasilkan oleh perusahaan-perusahaan yang lain pada waktu t + I sarna dengan jumlah output yang mereka hasilkan pada waktu t. Proses penyesuaian waktu kontinu dianalogikan dari proses penyesuaian waktu diskret. Dalam pasar terdapat n perusahaan yang memaksimumkan keuntungan single period (keuntungan yang diperoleh pada saat ini, tanpa memperhitungkan keuntungan yang abo diperoleh di masa yang akan datang ). Dengan bantuan fungsi Lipschitz dan fungsi Lyapunov diperoleh kondisi- kondisi yang membuat titik kesetimbangan Coumot stahil asimtotik untuk proses penyesuaian waktu kontinu. Untuk kurva pennintaan isoelastis P = AQ-lI" dengan e adalah elastisitas harga terbadap permintaan, jika jumlah perusahaan adalah 3, maka untuk e > Y:1, titik
Keyword: 

Judul: Kondisi Minimal Bagi Kesetimbangan Duopoli Cournot dan Stackelberg
Abstrak: Dalam model duopoli, dimana dalam pasar terdapat dua perusahaan yang saling bersaing, setiap perusahaan bertujuan memperoleh imbalan yang maksimum. Untuk mewujudkan tujuan tersebut diperlukan strategi. Kuantitas merupakan salah satu strategi perusahaan Strategi tersebut dapat dimainkan secara simultan atau sekuensial. Permainan simultan terjadi jika para pemain memutuskan bergerak pada saat yang sama, sedangkan permainan sekuensial terjadi jika para pemain memutuskan bergerak pada waktu yang berbeda. Permainan simultan dengan kuantitas sebagai strategi yang dipilih akan menghasilkan model duopoli Cournot, sedangkan permainan sekuensial dengan kuantitas sebagai strategi yang dipilih akan menghasilkan model duopoli Stackelberg. Karya tulis ini membahas bagaimana suatu kondisi minimal pada harga pasar dan fungsi biaya perusahaan akan menyebabkan perusahaan lebih memilih model duopoli Cournot atau Stackelberg, sehingga imbalan yang didapatnya maksimum. Harga pasar yang log konkaf akan menimbulkan model duopoli Cournot. Pada kasus ini pilihan koresponden tanggapan terbaiknya merupakan fungsi turun. Jika harga pasarnya log konveks dan tak ada biaya produksi, pilihan koresponden tanggapan terbaiknya merupakan fungsi naik dan akan menimbulkan model duopoli Stackelberg.
Keyword: 

Judul: Phylogeography and Species Limits in the Papuan White Snake (Micropechis ikaheka) (Reptilia: Serpentes: Elapidae)
Abstrak: Papua white snake, Micropechis ikaheka, has been distingushed into two subspecies M.i. ikaheka and M.i. fasciatus. However, due to lack of data on their morphology, distribution and ecology, both subspecies often ignored in scintific discussions and refers only byas , Micropechis ikaheka. This study was designed to document the differences between M.i. ikaheka and M.i fasciatus by using scales characteristics and reproductive organ or hemipenes. The study also examine, zoogeography, habitat, diet and cannibalism of both subspecies to better understanding the the ecology of one of the most venomous snakes in the world. This study consists of three topics with method and also different in the size samples, respectively. The first study is the histology and microtopography of the skin were studied using paraffin method and Scanning Electron Microscope (SEM). The second is the hemipenis were examined by following Myers and Cadle (2003), and Zaher and Prudente (2003). The third is the abdominal surgery was carried out to document diet type and the investigate phenomenon of cannibalism in the snake. Specimens for this study came from the collection from Museum Zoologicum Bogoriense (MZB) and Universitas Negeri Papua’s Laboratory (LZU). The research result also indicated that the markers of skin and hemipenis described the same structure and microornamentation in all M. ikaheka groups being compared. Based specimens examined morphological descriptions do not s support the further differentiation in Micropechis. In short, two markers that used in this study could not sufficiently indicate the differences in the level of species and subspecies of M. ikaheka. The study, however, were able to delineate zoogeography and skin color patterns, which fall into four groups: M. i. ikaheka; M. i. fasciatus. M. i. ssp. “intermediate”; and M. i. ssp “black”. This study also revealed that color variations did not overlap in their geographic distribution. It is therefore, it suggested that environmental factors may contribute to the skin color variations. It also assumed that habitat discontinuous and biogeography factors may also cause the loss of the connection between the original populations (vicarians) or follow colonization events (dispersal). The examined of 22 stomach contents of M. ikaheka shows this species is carnivorous, and prey on vertebrates such as amphibians, fish, reptiles, and Mammals. These snakes are opportunistic predators since they prey on all that can be captured, but mainly reptiles (61.5%), followed by mammals and fish (both 15.4%), and amphibians (7.7%). Although categorized as terrestrial animal, the diet study showed that M. ikaheka snakes often go into the water to hunt for fish (the sample from Yapen island), including eel (the sample from Aru island). Based on prey items indentified, there is evidence that M. ikaheka is cannibal. At this time, there still no record on reason for cannibalism, but it is assumed that cannibalism was due to competition between populations and means to control population.
Keyword: geographic variation, white snake, papua