Judul: Aktivitas Terbang Harian dan Mencari Polen Trigona laeviceps Smith di Perkebunan karet (Hevea braziliensis) dan Kelapa Sawit (Elaeis guineensis)
Abstrak: Conversion of forest to plantations affect the stability of ecosystems i.e. food webs and environmental factors. Stingless bee Trigona can be used as a model to understand the land conversion effect. This research were aimed to study daily flight activity of Trigona laeviceps and forage for pollen at oil palm and rubber plantations. Observation of daily flight activity and pollen collection activity of T. laeviceps were conducted in 26 days at oil palm and rubber plantations. The behaviour observations were taken from 05:00 to 18:10 and the observations were clustered into three groups, i.e. morning, noon and afternoon groups. The correlation of environmental effects (temperature, humidity, light intensity) activity to T. laeviceps behaviour were analysed by using Principle Component Analysis and Pearson correlation. The results of this study showed that pollen collection activity of T. laeviceps in oil palm plantations were commenced from 08.00 having peak activity at 12:00 to 12:10 while from 07.30 in pollen collection (peak activity at 12:30 to 14:10) for T. laeviceps in rubber plantation. Daily flight activity and pollen collecting T. laeviceps on each colony, was higher during noon (11:00 to 14:10) compared to morning and afternoon activities. Significant Pearson correlations were observed between environmental factors (temperature, humidity and light intensity) with daily flying activities and pollen collection. However, non-significant correlation occured between temperature and pollen collection activity in oil palm plantation.
Keyword: 

Judul: Aktivitas dan Produktivitas Lebah Trigona laeviceps di Kebun Polikultur dan Monokultur Pala (Myristica fragrans)
Abstrak: Trigona laeviceps is belong to the family Apideae. It has belong to no sting (stingless bee) and produce propolis, honey and bee pollen. This study aimed to study and compare the activity and productivity of Trigona laeviceps in polyculture and monoculture plantation nutmeg (Myristica fragrans). The study used completely randomized with type of garden (policultures and monocultures of nutmeg) Trigona activity and productivity (honey, pollen, propolis and development of colonies) were the variables and the obtained data were analyzed by ANOVA T - test with 95% confidence interval. observation the activity in and out in the morning until late afternoon (from 06:00 to 17:00), and productivity seen from the weight indication colony, honey, propolis and bee pollen. Trigona bee activity in the nutmeg monoculture plantation (83 %) was higher than in polyculture garden (84 %) and determined by light intensity. Activity in the garden polyculture affected by temperature pollen and propolis production percentages were higher in policulture plantation, while Trigona colonies in nutmeg monoculture had a better development. However, in this study, ambient factors (temperature, Rh, and light intensity) do not significantly determined variation in Trigona productions.
Keyword: 

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
Keyword: