Judul: Potential of bacterial simbionts of seagrass as preventing marine Biofouling
Abstrak: Biofouling is defined as the attachment and growth of microorganisms (microbial fouling) and macroorganisms (macrofouling) on solid surface. Biofouling bacteria also result on surface of marine plant seagrass as symbiotic. Bacteria-seagrass association that occur on the surface have been known to produce secondary metabolites that have important ecological roles, including prevention from pathogen infection and fouling organisms. A research aimed at the bacterial symbionts of seagrass Enhalus acoroides, Thalassia hemprichii and Syringodium isoetifolium as defense marine biofouling was performed. Bacterial symbionts including endophytes and epiphytes were isolated from the seagrass. Marine biofilm-forming bacteria had been isolated from the fiber and wooden panels from the surrounding colonies. Epiphyte isolate found more than endophyte isolate, however more biological activity was found among endophyte compare to epiphyte against biofilm-forming bacteria. Bacterial endophyte inhibited more biofilm-forming bacteria than epiphyte. Extract endophytes and epiphytes bacteria also inhabited biofilm-forming bacteria. Field experimental of extract bacteria show that extract of two bacteria spesies cannot obtained fouling organisms identified as Virgibacillus genus and one identified as Bacillus genus. Bacterial symbionts of seagrass in this experiment show potential source as natural marine antifouling.
Keyword: 

Judul: Potensi Lamun Jenis Enhalus acoroides dan Thalassia hemprichii Dari Pulau Pramuka, DKI Jakarta Sebagai Bioantifouling
Abstrak: Biochemically, seagrass has natural antifouling compounds potential to substitute harmful compund of TBT (tributhyl tin) in the antifouling paint. The aim of this study was to explore potential seagrass as bioantifouling materials. Particulary of Thalassia hemprichii and Enhalus acoroides extraction was performed using two solvents: methanol (polar) and n-hexane (non-polar). The results showed that extracts of Thalassia hemprichii and Enhalus acoroides contains flavonoids, a chemical compound potential as bioantifouling. Based on toxicity tests using Brain Shrimp Lethal Toxic (BSLT) method, methanol extract of Enhalus acoroides was more toxic (5.74 ppm) than n-hexane extract (1309.42 ppm). Biofilm inhibitory activity assay showed that inhibition performance seagrass extract (200 mg/ml) were weak (1.00 mm) to moderate (5.33mm).
Keyword: 

Judul: Pemodelan Nilai Tukar Rupiah Terhadap US Dollar Menggunakan Deret  Waktu Hidden Markov Dua Waktu Sebelumnya
Abstrak: Nilai tukar Rupiah terhadap US Dollar mengalami perubahan setiap waktunya dalam periode yang panjang dan perubahan yang terjadi mungkin terjadi kembali di masa mendatang. Jika penyebab kejadiannya tidak diamati secara langsung dan membentuk suatu rantai Markov maka perubahan nilai tukar Rupiah dapat dimodelkan dengan model deret waktu hidden Markov. Untuk menggambarkan perilaku nilai tukar Rupiah terhadap US Dollar, dalam karya ilmiah ini digunakan model deret waktu hidden Markov dua waktu sebelumnya. Model ini mengasumsikan bahwa nilai tukar Rupiah terhadap US Dollar bergantung pada rantai Markov yang merupakan penyebab kejadian yang tidak diamati dan nilai tukar Rupiah dua waktu sebelumnya.
Keyword: