Exploring Customers’ Preferences for Online Games

Online content providers who use the Internet to distribute content experience an extremely competitive business environment. To survive in this environment, they have started charging a fee for the content that they provide. However, there have been very few success stories in commercializing online content. Although one of few success stories is the online game, it still has customers’ psychological resistance against paying a high fee for playing games. To pay back their high R&D or development costs quickly, many online game producers have a tendency to assign high prices to their online games. Without examining customers’ perceived prices for online games, many online game producers have tended to decide prices from their perspectives. Although many online game-related research works have focused on psychological and technical aspects, very few works have examined online gamers’ preferences carefully. This study aims at exploring online gamers’ preference by measuring their WTP (Willingness To Pay) for online games

Using RTT Variability for Adaptive Cross-Layer Approach to Multimedia Delivery in Heterogeneous Networks

A holistic approach should be made for a wider adoption of a cross-layer approach. A cross-layer design on a wireless network assumed with a certain network condition, for instance, can have a limited usage in heterogeneous environments with diverse access network technologies and time varying network performance. The first step toward a cross-layer approach is an automatic detection of the underlying access network type, so that appropriate schemes can be applied without manual configurations. To address the issue, we investigate the characteristics of round-trip time (RTT) on wireless and wired networks. We conduct extensive experiments from diverse network environments and perform quantitative analyses on RTT variability. We show that RTT variability on a wireless network exhibits greatly larger mean, standard deviation, and min-to-high percentiles at least 10 ms bigger than those of wired networks due to the MAC layer retransmissions. We also find that the impact of packet size on wireless channel is particularly significant. Thus through a simple set of testing, one can accurately classify whether or not there has been a wireless network involved. We then propose effective adaptive cross-layer schemes for multimedia delivery over error-prone links. They include limiting the MAC layer retransmissions, controlling the application layer forward error correction (FEC) level, and selecting an optimal packet size. We conduct an analysis on the interplay of those adaptive parameters given a network condition. It enables us to find optimal cross-layer adaptive parameters when they are used concurrently.IEEE Circuits & Systems Societ

The efficacy of preoperative PET/CT for prediction of curability in surgery for locally advanced gastric carcinoma

<p>Abstract</p> <p>Background</p> <p>The benefits of preoperative ¹⁸FDG-PET/CT for gastric cancer remain uncertain. The aim of this study was to investigate the effects of preoperative ¹⁸FDG-PET/CT on the surgical strategy for locally advanced gastric cancer retrospectively.</p> <p>Methods</p> <p>From January 2007 to November 2008, ¹⁸FDG-PET/CT was performed in 142 patients who had been diagnosed with advanced gastric cancer by computed tomography or gastrofiberscope findings.</p> <p>Results</p> <p>Detection rates were 88.7% (126/142) for primary tumors and 24.6% (35/142) for local lymph nodes (LN). Nine patients with metastatic lesions underwent induction chemotherapy without operation. Of 133 patients subjected to operation, positive FDG uptake in primary tumors (<it>p </it>= 0.047) and local lymph nodes (<it>p </it>< 0.001) was related to non-curable operations. The mean standard uptake value (SUV) of primary tumors of patients who underwent non-curable operations was significantly higher than that of patients with curable operations (<it>p </it>= 0.001). When the SUV was greater than 5 and FDG uptake of LN was positive, non-curable operations were predicted with a sensitivity of 35.2%, a specificity of 91.0% and an accuracy of 76.7%.</p> <p>Conclusions</p> <p>High SUV of the primary tumor and positive FDG uptake in local lymph nodes at PET/CT could predict non-curative resection in locally advanced gastric cancer. Therefore, information from preoperative PET/CT can help physician decisions regarding other modalities without laparotomy.</p

Factors Affecting Endoscopic Curative Resection of Gastric Cancer in the Population-Based Screening Era

Background/Aims Since population-based screening for gastric cancer in Korea was implemented, endoscopic treatment of early gastric cancer has become increasingly popular. This study investigates factors affecting endoscopic curative resection of early gastric cancer in population-based screening for gastric cancer. Methods We retrospectively reviewed data of patients with newly diagnosed gastric cancer who underwent treatment at Seoul St. Mary’s Hospital. All patients completed questionnaires about clinical information, including interval between surveillance tests for gastric cancer. Results Of 469 gastric cancer patients, 147 (31.3%) had undergone curative endoscopic resection, 260 (55.4%) had undergone curative surgical resection, and 62 (13.3%) underwent non-curative resection or were in an inoperable state. Patients with curative endoscopic resection had fewer alarm symptoms/signs than other groups. In multivariate analysis, regular surveillance endoscopy was the only factor predicting curative endoscopic resection (odds ratio [OR], 6.099; 95% confidence interval [CI], 2.532–14.933). In addition, patients undergoing gastric cancer screening had a significantly higher rate of endoscopic curative resection compared with subjects who had never been screened. (1-year interval: OR, 49.969; 95% CI, 6.340–393.827, 2-year interval: OR, 15.283; 95% CI, 1.833–127.406, over 2-year interval: OR, 10.651; 95% CI, 1.248–90.871). Shorter screening test intervals were associated with higher rates of endoscopic curative resection. Conclusions Regular surveillance testing was the independent factor predicting curative endoscopic resection of gastric cancer

Copy Number Deletion Has Little Impact on Gene Expression Levels in Racehorses

Copy number variations (CNVs), important genetic factors for study of human diseases, may have as large of an effect on phenotype as do single nucleotide polymorphisms. Indeed, it is widely accepted that CNVs are associated with differential disease susceptibility. However, the relationships between CNVs and gene expression have not been characterized in the horse. In this study, we investigated the effects of copy number deletion in the blood and muscle transcriptomes of Thoroughbred racing horses. We identified a total of 1,246 CNVs of deletion polymorphisms using DNA re-sequencing data from 18 Thoroughbred racing horses. To discover the tendencies between CNV status and gene expression levels, we extracted CNVs of four Thoroughbred racing horses of which RNA sequencing was available. We found that 252 pairs of CNVs and genes were associated in the four horse samples. We did not observe a clear and consistent relationship between the deletion status of CNVs and gene expression levels before and after exercise in blood and muscle. However, we found some pairs of CNVs and associated genes that indicated relationships with gene expression levels: a positive relationship with genes responsible for membrane structure or cytoskeleton and a negative relationship with genes involved in disease. This study will lead to conceptual advances in understanding the relationship between CNVs and global gene expression in the horse

Genome-wide analysis of DNA methylation patterns in horse

Background: DNA methylation is an epigenetic regulatory mechanism that plays an essential role in mediating biological processes and determining phenotypic plasticity in organisms. Although the horse reference genome and whole transcriptome data are publically available the global DNA methylation data are yet to be known. Results: We report the first genome-wide DNA methylation characteristics data from skeletal muscle, heart, lung, and cerebrum tissues of thoroughbred (TH) and Jeju (JH) horses, an indigenous Korea breed, respectively by methyl-DNA immunoprecipitation sequencing. The analysis of the DNA methylation patterns indicated that the average methylation density was the lowest in the promoter region, while the density in the coding DNA sequence region was the highest. Among repeat elements, a relatively high density of methylation was observed in long interspersed nuclear elements compared to short interspersed nuclear elements or long terminal repeat elements. We also successfully identified differential methylated regions through a comparative analysis of corresponding tissues from TH and JH, indicating that the gene body regions showed a high methylation density. Conclusions: We provide report the first DNA methylation landscape and differentially methylated genomic regions (DMRs) of thoroughbred and Jeju horses, providing comprehensive DMRs maps of the DNA methylome. These data are invaluable resource to better understanding of epigenetics in the horse providing information for the further biological function analyses.open1