Judul: Komposisi Vegetasi dan Potensi Tumbuhan Obat di Hutan Kerangas Kabupaten Belitung Timur Provinsi Kepulauan Bangka Belitung
Abstrak: Heath forest on East Belitung is thought to have a diversity of plant species that can be used for medications. However, the information about it has not been revealed yet. Therefore, research about composition of vegetation and potential medicinal plants in the heath forest is necessary. This research was conducted in the primay heath forest (Rimba), secondary heath forest (Bebak) and particular heath forest (Padang) at East Belitung on July to Agustus 2011. The collected data includes species of plants (local name and scientific name), species of plants used medicine and part of plants that is used for medicine. Methods that is used to collect the data is the analysis of vegetation and interview method. Analysis vegetation was done by using combination of line and compartment method. The number of lines in each forest type are 10 with each line size is 10 m × 100 m and the distance between the lines is 50 m. The research results 224 species of plants in the heath forest obtained from different habitus and growth rates. Species with the highest value of importance on seedling, bush/shrub, herbaceous, liana, rattan and pandan is the samak (Syzygium lepidocarpa) amounted to 20.2% in the primary heath forest, pulas (Guioa pleuropteris) amounted to 12.57% in the secondary heath forest and kucai padang (Fimbristylis sp.) amounted to 51.14% in the particular heath forest. Species with the highest value of important on sapling is betor belulang (Calophyllum lanigerum) amounted to 17.27% in the primary heath forest, kiras (Garcinia hombroniana) amounted to 21.50% in the secondary heath forest and sekuncong (Leptospermum flavescens) amounted to 88.46% in the particular heath forest. Species with the highest value of important on tree is seru (Schima wallichii) amounted to 53.36% in primary heath forest, seru (Schima wallichii) amounted to 103% in secondary heath forest and sekuncong (Leptospermum flavescens) amounted to 180.2% in the particular heath forest. The number of medicinal plant species are identified based on knowledge of local communities as much as 101 species. Plant family which were most widely utilized is Myrtaceae. Tree is the most common habitus of medicinal plant to be used. The part of plants which is widely used is root and the most numerous group of diseases cured with medicinal plant is diseases of body resilience system (fever). Composition of vegetation in heath forest is potential as a germ plasm reserve of medicinal plants in Indonesia. Heath forest resources conservation can support sustainability of species and benefits to community around the forest.
Keyword: 

Judul: Etnobotani dan Potensi Tumbuhan Berguna di Kampung : Keay, Kabupaten Kutai Barat, Kalimantan Timur.
Abstrak: Keay Village is one of villages in West Kutai Regency, East Kalimantan. There are four ethnic groups occupying this village, i.e. Dayak, Javanese, Toraja, and Bugis. Dayak is the dominant ethnic group occupying the village, which still has traditional wisdom/knowledge in plants use. Ethnobotany is expected to document and hand on the knowledge of Dayak Benuaq ethnic group in using plants, and keep the knowledge from being loss. Data were collected through literature study, interview, field survey and inventory, vegetation analyses, and herbarium collection. Data on plants species found were classified in to classification of use, classification of illnesses, habitués percentage and parts of plants used, important value index, Shannon-Wienner species diversity index, and percentage of useful plants potential. There were 396 plant species found through ethnobotany and vegetation analyses, which was categorized into three categories i.e. plant species found through ethnobotany (285 species), plant species found through vegetation analyses in natural forest (158 species), plant species found through vegetation analyses in hevea plantation (34 species). There were 285 species belong to 78 families which uses had been known and grouped into 16 use groups. There were 53,79% of plants species in natural forest had the potential as useful plants, while in hevea plantation there were 50% of that species had the potential as useful plants. Dominant plant species in natural forest was keranyiq (Fordia johorensis) with IVI (Important Value Index) of pole level as much as 19,69%, sapling (25,46%), and seedling (24,67%). In hevea plantation, dominant plant species was hevea (Hevea brasiliensis) with IVI the highest IVI of tree level as much as 300%, pole (284,63%), sapling (143,59%), and seedling (52,42%). Plants use most widely used for medicinal as much as 95 species of 43 families. The community uses more plants from the forest than from the plantation, because there were more useful plants species in the forest. Potential useful plants at the forest of Keay village included mara uleq (Eurycoma longifolia), uwe (Korthalsia sp., Calamus sp., Daemonorops sp.), empulung (Asplenium nidus), and kerakap (Platycerium bifurcatum). Other potential other than plants potential in the natural forest was hevea (Hevea brasiliensis).
Keyword: 

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
Keyword: