Judul: ANALISIS DAYA TAHAN PADA KASUS KEMATIAN BAYI DI INDONESIA DENGAN SURVIVAL TREE DAN RANDOM SURVIVAL FOREST
Abstrak: Pembangunan kesehatan merupakan aspek penting dalam pembangunan nasional karena kesehatan yang baik berperan penting dalam pembangunan manusia yang berkelanjutan. Penurunan angka kematian, termasuk Angka Kematian Bayi (AKB), menunjukkan peningkatan status kesehatan masyarakat sebagai manifestasi keberhasilan pembangunan nasional. AKB di Indonesia dalam 50 tahun terakhir telah menurun secara signifikan sebesar 90%, namun masih jauh dari target tahun 2030. Tindakan pencegahan diperlukan untuk lebih menekan AKB. Penelitian ini bertujuan untuk memodelkan kematian bayi di Indonesia dengan menerapkan Survival Tree dan Random Survival Forest pada data kelangsungan hidup bayi. Berbeda dengan regresi Cox yang terbatas oleh asumsi proportional hazards, metode ini tidak memerlukan asumsi sebaran apapun dan dapat secara otomatis menangkap interaksi antara peubah dan pola hazard yang kompleks tanpa menyatakan interaksi sebelumnya. Hasil penelitian menunjukkan bahwa model terbaik adalah model Random Survival Forest setelah hyperparameter tuning dengan concordance index (c-index) sebesar 0,808. Berdasarkan tingkat kepentingan peubah dari model terbaik, diperoleh peubah imunisasi, perilaku merokok ibu, berat badan lahir rendah, dan status ibu bekerja, sebagai empat peubah yang paling penting untuk memprediksi kelangsungan hidup bayi., Health development is a crucial aspect of national development, as good health plays an important role in sustainable human development. A decrease in mortality rates, including the Infant Mortality Rate (IMR), indicates an improvement in public health status as a manifestation of successful national development. Over the past 50 years, the IMR in Indonesia has significantly decreased by 90%, yet it is still far from the 2030 target. Preventive measures are necessary to further reduce the IMR. This study aims to model infant mortality in Indonesia by applying Survival Tree and Random Survival Forest to infant survival data. Unlike Cox regression, which is limited by the proportional hazards assumption, these methods is not limited with any assumption and can automatically capture interactions between variables and complex hazard patterns without specifying interactions beforehand. The results of the study show that the best model is the Random Survival Forest model after hyperparameter tuning, with a concordance index (c-index) of 0.808. Based on the variable importance levels from the best model, the variables of immunization, mother's smoking behavior, low birth weight, and mother's employment status were identified as the four important variables for predicting infant survival.
Keyword: analisis daya tahan, fungsi hazard, kematian bayi, random survival forest, survival tree

Judul: Cox Regression Model for Infant Survival in Perinatal Period
Abstrak: Penelitian ini berupaya untuk mengamati berbagai faktor yang diperkirakan beresiko terhadap kematian bayi dan daya tahan hidup bayi di masa perinatal. Data berasal dari RS Dr. Hasan Sadikin, Bandung periode Januari hingga Juni 1998. Peubah-peubah penjelas yang diamati adalal1 riwayat aborsi, asfiksia, prematuritas, berat bayi ketika lallir, pendidikan ibu, dan usia ibu ketika melallirkan. Peubah responnya adalah lamanya bayi bertahan hidup dalam masa perinatal, ditambal1 satu peubah indikator untuk kctersensoran pengamatan. Analisis peubah tunggal dilakukan untuk melihat peranan masing­masing peubah dan lalu analisis peubah ganda untuk melihat peranan peubah secara bersama-sama. Peubah yang pengaruhnya nyata adalah berat bayi ketika lahir, prematuritas, dan asfiksia. Pengaruh asfiksia paling besar terhadap resiko kematian bayi karena menentukan hidup bayi di menit-mcnit pertamanya setelah lallir. Resiko relatif untuk peubal1 berat bayi ketika lahir, prematuritas, dan asfiksia berturut-turut adalah 1.42, 1.34, dan 2.55. Resiko kematian terbesar dalam masa perinatal terdapat pada bayi yang mengalarni asfiksia, prematur dan bcrat lahimya kurang dari 2500 gram. Rcsiko kcmatian tcrkccil tcrdapat pada bayi yang tidak mcngalarni asfiksia, tidak prcmatur, dan bcrat Iahimya lcbih dari 2500 gram.
Keyword: 

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.