Judul: Antioxidant Activity of Waterleaf (Talinum triangulare (Jacq.) Willd) Cultivated with Organic Fertilizers during the Rainy Season
Abstrak: Talinum triangulare (Jacq.) Willd, known as ginseng Jawa or kolesom Jawa in Indonesia, is one of tropical plants that has been widely used as traditional herbal medicine and consumed as vegetable in Indonesia. The leaf from the plant contains bioactive compound identified as flavonoid which can function as antioxidant. The objective of this research was to measure the antioxidant activity and total phenolic compound of waterleaf in five different treatments of organic fertilization. Extraction of the leaf was carried out with the method of ultrasound assisted extraction/UAE (sample:MeOH=1:10 b/v, t=20 minutes, cold extraction room temperature). The present research resulted that the different organic fertilizer treatments significantly influenced the secondary metabolites content e.g. phenolic content of Talinum triangulare (Jacq.) Willd (p<0.05). High total phenolic content did not always exhibit high antioxidant activity as the highest total phenolic content group (PK+RP: 10.76 mg GAE/g dry sample) had weaker antioxidant activity (DPPH: 1.73 ± 0.01 mg AEAC/g GAE) than thus lower in phenolic content. Organic fertilizer RP+AS (rock phosphate and husk ash) treatment (7.36 ± 0.00 g GAE/g dry sample) exhibited the highest antioxidant activity in scavenging DPPH free radicals and strongest reducing power among all groups (2.06 ± 0.01 mg AEAC/g GAE; 0.022 ± 0.000 mg AEAC/g GAE respectively). Organic fertilizer influenced the secondary metabolite produced by the waterleaf
Keyword: Bogor Agricultural University (IPB), total phenolic content, Talinum triangulare (Jacq.) Willd, organic fertilization, DPPH, antioxidant activity

Judul: Waterleaf production and quality with organic and inorganic fertilizer
Abstrak: Three consecutive field experiments had been conducted at the IPB experimental station (Bogor, Indonesia), in March-July 2011 to study the effect of two types of fertilizer on waterleaf [Talinum triangulare (Jacq.) Willd.] production and quality in wet (March-May 2011) and dry (May-July 2011) seasons; while laboratory analysis was conducted from April to December 2011. The first experiment was in wet season and consisted of two sets of treatment, namely different rates of organic [cow manure (ton/ha) + guano (kg/ha) + hull ash (ton/ha), i.e. 6.1 + 75.6 + 2.7, 9.2 + 151.2 + 4.1, 12.3 + 226.8 + 5.5, 15.4 + 302.4 + 6.8, and 18.4 + 378.0 + 8.2] and inorganic [urea (kg/ha) + SP-36 (kg/ha) + KCl (kg/ha), i.e. 50 + 20 + 50, 75 + 40 + 75, 100 + 60 + 100, 125 + 80 + 125, and 150 + 100 + 150] fertilizer. The second experiment was in dry season and consisted of two sets of treatment, namely different rates of organic and inorganic fertilizer (same as the first experiment). The third experiment was in dry season and consisted of four sets of treatment, namely different rates of organic (6.1 + 75.6 + 2.7, 12.3 + 226.8 + 5.5, and 18.4 + 378.0 + 8.2; the fertilizers and units were as above) and inorganic (50 + 20 + 50, 100 + 60 + 100, and 150 + 100 + 150; the fertilizers and units were as above) fertilizer, and organic and inorganic fertilizer residue (without fertilizer re-application). The experimental design for each set was randomized block design. Since fertilizer rates did not significantly affect the variables, means value of each set were compared by using t-student’s test. Generally, the result from these research suggested that (1) In wet season, waterleaf with organic fertilizer did not have any difference in shoot production; while in dry season, these treatments resulted in higher shoot production compared to those with inorganic fertilizer; (2) Waterleaf antioxidant capacity of organic and inorganic treatments were not significantly different in the same planting season; (3) The primary (vitamin C) and secondary (flavonoid) metabolites with antioxidant functions were higher in dry season compared to those in wet season; (4) Biosynthesis pathway of waterleaf phenolic compounds in wet season was different from that in dry season. It was suspected that phenolic compounds were synthesized predominantly via phenylpropanoid pathway in wet season and via acetate-malonate pathway in dry season; (5) Without organic or inorganic fertilizer re-application in the new planting season, yield of waterleaf shoot decreased approximately 26-50 % but did not degrade the quality.
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Judul: Estimating Parameter and the Convergence of Parameter Estimator of Poisson Hidden Markov Model
Abstrak: Model hidden Markov terdiri dari sepasang proses stokastik yaitu proses observasi dan proses yang memengaruhi observasi. Proses stokastik yang memengaruhi observasi ini diasumsikan membentuk rantai Markov dan tidak diamati. Model Poisson hidden Markov (MPHM) adalah salah satu model hidden Markov diskret dan proses observasinya jika diketahui proses yang memengaruhinya diasumsikan menyebar Poisson., A hidden Markov model (HMM) consists of a pair of stochastic processes, that is the observation process and process that affected observation. The stochastic process which causes this observation is assumed to form a Markov chain and is not observed. Poisson hidden Markov models (PHMM) is one of the discrete HMM and the observation process given the cause is assumed having a Poisson distribution.
Keyword: Poisson hidden Markov model, Forward-Backward algorithm, Expectation Maximization algorithm