Judul: Analisis Daya Tahan Pengguna Nomor Kartu Prabayar Telekomunikasi
Abstrak: Telecomunication prepaid customer has increased significanly compared to postpaid customers. The growth in prepaid is driven by a end-to-end simple ecosystem that is built by telecommunication operator, for example started pack can be bought anywhere anytime, retail outlet for voucher can be found everywhere. That simplicity has been creating another effect to customer in which they can easily switch sim card after the balance run out.That behavior driven by regulation in buying prepaid SIM that not optimum in which customer data can not be validated. The impact of rotational prepaid customer gives a high cost to telecommunication provider and the availability of number becomes limited. For customers, the impact of rotational SIM has made them vulnerable from spamming. Those impact can be minimized if regulator and telecommunication operator knows the factors that drives customer changing their SIM cards.This study is to define the factors which has driven customers in buying new SIM cards, by survival model of prepaid customers and to define the probability loyal customer based on significant characteristics. Data in this study is based on survey to 300 prepaid customers in DKI Jakarta. Survival Analysis is a statistical technique to define the pattern of survivals based on failure times and survival times. Data of survival times is measured from the time customer bought the SIM card until event in which customer stop using it. In his study, characteristic that are both significantly effect to drives rotational customer is age, voucher price and income. Based on the value of its hazard ratio, age 16 until 18 years, income 1.5 until 3 million voucher price under 10 thousand rupies category is an indicator that gives customer the greatest influence in determining the level of one’s impact of rotational prepaid customer.
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Judul: Analisis Faktor-Faktor yang Mempengaruhi Perpindahan Merek pada Pelanggan Kartu Prabayar GSM
Abstrak: Cellular industry of Indonesia has grown many folds in recent years. This situation has originated a hyper competition among major cellular service providers in Indonesia. In this competitive cellular market, customer switching is injurious for every telecommunication company. This study explore relationship between customer loyalty and variety seeking behavior on customer switching in cellular industry especially pre paid GSM customer. Customer loyalty influenced customer value, satisfaction, and switching barrier. Factor that influence variety seeking behavior are variety seeking need and characteristic of product category. This research was conducted in Jakarta, primary data was collected by a set of questionnaire and allocated to 230 prepaid GSM customer. Research methods used structural equation modeling (SEM) using AMOS version 18. Findings revealed that customer value and switching barrier have significant effect on customer loyalty; variety seeking need has significant positive effect on variety seeking behavior; customer loyalty has significant negative effect on brand switching; and variety seeking behavior has significant positive effect on brand switching.
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Judul: Heterologous Expression Of Endo-Β-Xylanase From Bacillus Pumilus Strain Bcrs-01 In Escherichia Coli.
Abstrak: Xylanases are glycoside hydrolase family 11 which depolymerise xylan in the plant cell wall, the most excessive form of hemicellulose. Endo-β-xylanases (EC 3.2.1.8) are most important to breakdown β-1,4-glicoside bond of xylan to produce disaccaride xyloolygosaccaride (XOs) and xylose (monomer). Bovine rumen fluids have potential to obtain endo-β-xylanase produced of bacteria. The objectives of this study were to obtain xylanase producing bacteria and to express xynA gene encoding endo-β-xylanase from bacterium in Escherichia coli. Twenty nine isolate bacteria have been succesfully isolated from bovine rumen fluid in agar medium containing birchwood xylan. Isolate BCRS-01 bacterium was previously screened for the high production of xylanase. Based on 16S rRNA gene sequence analysis, BCRS-01 showed high similarity (99%) to Bacillus pumilus (accession number NR043241). The crude xylanase had optimal activity at 55oC, pH 7.0. Furthermore, the crude xylanase exhibited broad pH stability from 4.0 to 10.0 and remained more than 60% and 40% of its activity after incubation at pH 4.0 until 10.0, respectively for 60 min. It also showed a stability at temperature 25-50oC since it retained 80% and 50% of its activity when incubated at 50oC or 30 and 60 min, respectively. The xylanase activity was strongly inhibited by Ca2+ and Cu2+ at concentration 10 mM, and as little as 1 mM for Mn2+. Therefore, this xylanase has potentially used as additive feeds in animal feed industry. The DNA sequence xynA gene encoded endo-β-xylanase was amplified and cloned into the expression vector pET-15by under the control of T7 promoter. The recombinant protein had succesfully expressed in Escherichia coli BL21 (DE3) pLysS. A protein recombinant of approximately, 26.7 kDa was observed on the SDS-PAGE analysis. Crude extract of recombinant endo-β-xylanase demonstrated activity of enzyme at 56 U mL-1 using birchwood xylan as a substrate at 55oC for 10 min.
Keyword: Bacillus pumilus, bovine rumen fluid, endo-β-xylanase, heterologous expression.