Judul: Biokompatibilitas Tandur Tulang Kombinasi Hidroksiapatit Asal Cangkang Telur Ayam dengan Kombinasi Trikalsium Fosfat, dan Kitosan pada Remodelling Tulang Domba Akibat Trauma Buatan
Abstrak: Every year, thousands of people suffer from various bone diseases caused by trauma, tumors, or fractures. Loss and substantial damage to the bone and in various operations such as removal of bone tumors, hip joint prosthesis fitting, and other bone damage have increased the need for allograft bone. This condition is exacerbated by the lack of an ideal bone substitute (Murugan and Ramakhrisna 2004). As a result, it takes a variety of synthetic materials to limit the amount of tissue used in the allograft bone. Although commercially bone substitute materials are available (eg. Osteocel® Plus, cancellous Vitoss® Synthetic Bone Filler, OrthoBlast® II, etc.) but none of were to be made in Indonesia. Moreover, the commercial material or fabric weave is still confidential. Another disadvantage of commercial bone substitute materials is their high price and limited availability in Indonesia. The objective of this study was to determine the best choice of bone substitution between combinations of hydroxyapatite-tricalcium phosphate (HATKF) and hydroxyapatite-chitosan (HA-K) for bone damage healing in sheep. The outcome of the study is expected to: (1) provide information about the efficacy of the two types of bone substitutes in terms of biocompatibility, osteoinduktif, and mechanical stability, (2) as a bone substitute material alternatives on the market, and (3) as the basis for its use in humans. We concluded that HA-TKF and HA-K implants did not cause significant disruption to the body. The healing process in the control bone were faster than both types of implanted bone grafts. However HA-TKF has good biocompatibility, biodegradability, bioresorbability, bioactivity and osteo conductivity properties than HA-K. Both types of implants have the potential to utilized as a bone substitute with further modifications such as: providing nanopore, changes in the composition of the implants, the use of implants in different bone, etc.
Keyword: Hydroxyapatite, Tricalcium phosphate, Khitosan, Biocompatibility, Bone graft

Judul: Evaluasi radiografi implan tulang Hidroksiapatit-Kitosan (Ha-K) dan Hidroksiapatit-Trikalsium Fosfat (Ha-TKF) pada domba sebagai hewan model untuk manusia
Abstrak: The study was aimed to compare in vivo osteogenesis potency of two bone implant combinations which used hydroxyapatite-chitosan (HA-C) and hydroxyapatite-tricalcium phosphate (HA-TCP). This study will describe the potential use of bone substitution material which implanted on sheep as animal model for human. Six local sheeps were used in this study. Both of the bone implants were shaped into a pellet form. The bone implants were inserted under aseptic surgery on the medial of the left tibia bone and as control the medial of the right tibia bone was drilled without bone implant. Bones were subjected to radiography examination at 0 day pre and post-surgery, 7 , 30 , 60 and 90 days post-surgery. The observation parameters are radiopacity, margination, and the shape of bone implant or bone defect under radiography evaluation. The result shown that the HA-TCP bone implant has better properties for biodegradability and bioresorbsibility than HA-C bone implant. In the other hand, the process of bone growth which implanted by HA-TCP bone implant was slow because the implant has no good osteoinductive properties. The both of implants were still stay in bone until the end of observation and the progress of osteogenesis did not show better result than the control.
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Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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