Judul: Penentuan Premi Optimal pada Portofolio Heterogen dengan Menggunakan Pemrograman Tak Linear
Abstrak: Asuransi merupakan salah satu cara yang dapat digunakan untuk meminimumkan kerugian yang disebabkan oleh kejadian tidak terduga. Sebagai kewajiban dari keikutsertaan dalam jasa asuransi, pihak tertanggung harus membayar sejumlah premi yang disepakati dengan perusahaan asuransi. Salah satu risiko yang dihadapi perusahaan asuransi yaitu jika premi yang dibayarkan tidak mencukupi pembayaran klaim yang diajukan. Oleh karena itu dalam menentukan premi, risiko tersebut perlu dipertimbangkan. Premi optimal dari suatu asuransi dapat ditentukan dengan menggunakan pemrograman tak linear. Pada portofolio heterogen yang terdiri dari sejumlah besar pemegang polis asuransi yang terbagi menjadi beberapa kelas di mana setiap pemegang polis berisiko. Untuk itu ditentukan premi optimal dengan menggunakan pemrograman tak linear. Pemrograman tak linear tersebut meliputi fungsi objektif yaitu meminimumkan jumlah beda kuadrat terboboti antara besarnya total klaim dan total premi yang dibayarkan, terhadap kendala persamaan linear yaitu tingkat risiko yang telah diberikan. Langkah pertama penentuan premi optimalnya adalah dengan menentukan titik ekstrem dari fungsi pada masalah optimasi, kemudian langkah selanjutnya adalah membuktikan bahwa titik ektrem tersebut adalah minimum dengan menggunakan matriks Hess di mana akan dibuktikan bahwa matriks Hess tersebut adalah matriks definit positif dengan menggunakan dua lema terkait matriks definit positif. Dengan langkah-langkah tersebut, maka diperoleh premi optimal untuk setiap kelas dari portofolio heterogen.
Keyword: nonlinear programming, optimal premium, heterogeneous portfolio

Judul: Penentuan Premi Optimum pada Portofolio Heterogen dengan Argumen Geometris Sederhana
Abstrak: Insurance is a process of risk transfering from insureds to insurers. Insureds pay premium as a transfered risk. Amount of premium satisfies the agreement of insureds and insurers in insurance policy. In heterogeneous portfolio, there are more than one classes based on risk level for policyholders. The risk level of each class is different. For each class, it has to be determined the optimal premium based on risk level. The determining of optimal premium is to avoid insurance company from bankrupt, but it does not incriminate policyholder. Optimal premium can be determined by using simple geometrical arguments. The method for determining premium is minimizing a weighted squared difference of the total premium and total claim. From this, we will get formula for pricing optimal premium for each class in heterogeneous portfolio. The formula can be used to determine allocations for pricing of optimal premium, which are uniform allocation, semi-uniform allocation, expected principle, and variance principle.
Keyword: simple geometrical arguments, optimal premium, heterogeneous portfolio

Judul: Biology and ecology of the buffalo fly, haematobia exigua de meijere (diptera:muscidae)
Abstrak: The life history of the buffalo fly was observed at room temperature of 27°-29.5°C and at a relative humidity of 48-68 percent. The eggs hatched after 17-22 hours, with an average of 18 hours. First instar larvae measured 1.25 + 0.16 mm long and 0.27 + 0.037 mm wide. reach the second larval stage. It took 6-12 hours to the second instar larvae measured 2.676 +0.187 mm long and 0.353 +0.028 mm wide. The second instar took about 12-24 hours to reach the third larval stage. The third instar measured 6.833 + 0.189 mm long and 0.919 + 0.051 mm wide. It took about 2-3 days for the third instar to become pupae. Duration of the pupal stage was about 5-7 days before the adults emerged. Under laboratory condition, the buffalo fly completed its life cycle in 9.5 to 10.5 days, whereas under field condition it took 9-14 days with an average of 10.5 days. The growth ratio which was based on the measurements of the cephalo-pharyngeal skeleton of each instar was 1.797. The preoviposition period was 8-12 days and mating usually occurred on the 6th or 7th day. The longevity of the male was 29 days, whereas it was 32 days in the female. The range of egg production under laboratory condition was between 20-139 per female fly. The belly and hind legs of the carabao were the most preferred habitat either during cloudy and cool dry or shiny and warm day. When the weather was clear and the carabao was in the shade, the flies tended to be more distributed particularly on the shoulder, dewlap, back and horns. The carabaos had relatively fewer Musca sp. and Stomoxys calcitrans than cattle; never the less carabaos had a higher infestation of buffalo fly than cattle. Oviposition occured either during the day or night but the buffalo flies were more active during the night than in the day time. The effect of various lengths of exposure time of manure in relation to the oviposition was profound. observed, the maximum number of the buffalo flies was occurred when the dung was exposed for 30 minutes. With increasing time of exposure the number and variety of insects also increase. It was evident that Sepsidae and psychodidae were the most dominant insects emerging from the dung. The number of buffalo flies also increased with increasing
Keyword: