Judul: Fern Spores Characterization in  Mount Tajam and Mount Lumut, Belitung
Abstrak: Belitung memiliki wilayah yang penting untuk disorot berupa hutan kerangas, yaitu ekosistem dengan media tanah yang miskin unsur hara. Salah satu keragaman flora yang dapat ditemukan di ekosistem ini adalah tumbuhan paku. Beberapa jenis tumbuhan paku memiliki ciri morfologi vegetatif yang mirip sehingga sulit diidentifikasi secara langsung. Oleh karena itu, ciri struktur reproduksi dibutuhkan untuk memantapkan identifikasinya. Penelitian ini bertujuan mendeskripsi ciri spora tumbuhan paku di Gunung Tajam dan Gunung Lumut, Belitung. Karakter yang diamati meliputi bentuk spora, ukuran spora, tipe laesura, dan tipe permukaan perispora. Spora diamati dengan mikroskop majemuk Olympus CX23 dan didokumentasi dengan kamera OptiLab. Spora diukur menggunakan perangkat lunak Image Raster. Data disusun dalam bentuk gambar, tabel karakter spora, dan kunci paralel. Hasil pengamatan menyajikan ciri spora dari 22 jenis tumbuhan paku yang diperoleh dari koleksi herbarium yang telah diidentifikasi. Tipe spora monolete dengan laesura garis ditemukan pada 11 jenis yang bervariasi pada bentuknya yaitu bulat dan lonjong. Tipe spora trilete dengan laesura triradiate ditemukan pada 11 jenis dengan bentuk yang bervariasi yaitu tetrahedral-bundar, bulat, dan berlobus. Tipe permukaan perispora sangat bervariasi antarmarga dan jenisnya. Hasil pengukuran spora berdasarkan rasio P/E memiliki nilai <1,00. Tipe ukuran spora yang ditemukan yaitu medium, besar, dan gigantik., Belitung has a highlighted area namely heath forest, which is an ecosystem with nutrient-poor soil media. One specific biodiversity of flora in this ecosystem is pteridophytes. Some species of pteridophytes have similar vegetative morphological features that are difficult to identify directly. Therefore, the characteristics of the reproductive structure are needed to strengthen its identification. This study aimed to identify the pteridophyte spore’s character from Mount Tajam and Mount Lumut Belitung. The observed spore characters are spore shape and size, laesure type, and perispore ornamentation type. Spores were observed using an Olympus CX23 compound microscope and documented using an OptiLab camera. Spore were measured using Image Raster software. Data is arranged in the form of figure, spore character table, and parallel keys. The observations present the spore characters of 22 species of pteridophytes obtained from the herbarium collections that have been identified. Eleven species have monolete spore types with linear laesure that vary in shape, sphere and ellipse. The other 11 species have trilete spore type with triradiate laesure having various shapes, tetrahedral-globose, sphere, and lobed. The surface type of perispores varies greatly between genera and species. The results of the spore measurement based on the P/E ratio had a value of <1.00. The spore sizes found are medium, large, and gigantic.
Keyword: identification, laesure, ornamentation, perispore, pteridophyta

Judul: Diversity of Reproductive Structures in Epiphytic Ferns in the Campus Area of IPB, Dramaga, Bogor
Abstrak: Institut Pertanian Bogor merupakan kampus dengan biodiversitas tinggi. Tumbuhan paku epifit menjadi salah satu tumbuhan yang sangat melimpah jumlah dan jenisnya, tetapi informasi struktur reproduksinya masih terbatas. Penelitian ini bertujuan mengkarakterisasi struktur reproduksi tumbuhan paku epifit yang tumbuh di kawasan kampus IPB, Dramaga, Bogor. Metode penelitian terdiri dari koleksi sorus, pengawetan dengan alkohol 70%, pengamatan menggunakan mikroskop majemuk yang dihubungkan pada kamera optilab, dan pengukuran menggunakan aplikasi imageRaster v2.1. Tumbuhan paku epifit yang diamati bervariasi pada susunan dan letak sorus serta ciri sporanya. Sorus berbentuk bulat dan garis. Sebagian besar sorus terletak pada tepi daun. Sebanyak 22 jenis tumbuhan paku yang memiliki spora bentuk monolete dengan laesura garis, satu jenis bentuk bulat, dan satu jenis bentuk tetrahedral-globose dengan laesura triradiate. Ukuran spora yang dijumpai yaitu medium, besar dan sangat besar. Semua spora memiliki nilai rasio P/E ≤1,00 dengan tipe peroblate, oblate, suboblate, oblate bulat dan prolate bulat. Permukaan perispora sangat beragam yaitu alate-angular, globules, shallow verrucae, verrucate, echinulate, tuberculate, rugate, globules, echinate, laevate, cristate, regulate, colliculate, granulose, dan costate-alate., Bogor Agricultural University is a campus with high biodiversity. Epiphytic ferns are one of the most abundant plants in terms of numbers and types, but information on their reproductive structures is still limited. This study aims to characterize the reproductive structure of epiphytic ferns that grow in the IPB campus area, Dramaga, Bogor. The research method consisted of a collection of sorus, preserving it with 70% alcohol, observing using a compound microscope connected to an optilab camera, and measuring using the imageRaster v2.1 application. The observed epiphytic ferns varied in the arrangement and location of the sorus and the characteristics of the spores. The sorus was round and line. Most of the sorus were located on the leaf margins. A total of 22 fern species had monolete spore with line laesura, one species had round spore, and one species had tetrahedral-globose spore with triradiate laesura. Spore sizes found were medium, large, and very large. All spores had a P/E ratio value of ≤1.00 with peroblate, oblate, suboblate, round oblate, and round prolate types. The surface of the perispora is very diverse, namely alate-angular, globules, shallow verrucae, verrucate, echinulate, tuberculate, rugate, globules, echinate, laevate, cristate, regulate, colliculate, granulose, and costate-alate.
Keyword: biodiversity, characterization of spores, perispore surface, sorus

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
Keyword: