Suchergebnisse

Periodontitis is the most common cause for tooth loss in adults and advanced types affect 10-15% of adults worldwide. The attempts to save tooth and regenerate the periodontal apparatus including cementum, periodontal ligament, and alveolar bone reach to the dental tissue-derived stem cell therapy. Although there have been several periodontitis models suggested, the apical involvement of tooth root is especially challenging to be regenerated and dental stem cell therapy for the state has never been investigated. Three kinds of dental tissue-derived adult stem cells (aDSCs) were obtained from the extracted immature molars of beagle dogs (n = 8), and ex vivo expanded periodontal ligament stem cells (PDLSCs), dental pulp stem cells (DPSCs), and periapical follicular stem cells (PAFSCs) were transplanted into the apical involvement defect. As for the lack of cementum-specific markers, anti-human cementum protein 1 (rhCEMP1) antibody was fabricated and the aDSCs and the regenerated tissues were immunostained with anti-CEMP1 antibody. Autologous PDLSCs showed the best regenerating capacity of periodontal ligament, alveolar bone, and cementum as well as peripheral nerve and blood vessel, which were evaluated by conventional and immune histology, 3D micro-CT, and clinical index. The rhCEMP1 was expressed strongest in PDLSCs and in the regenerated periodontal ligament space. We suggest here the PDLSCs as the most favorable candidate for the clinical application among the three dental stem cells and can be used for treatment of advanced periodontitis where tooth removal was indicated in the clinical cases. (C) 2011 Cognizant Comm. Corp. ; This work was supported by the grants from the National Research Foundation of Korea (NRF) grant funded by the Korea government (MEST) (No. 2009-0066366) to Pill-Hoon Choung. ; 10

The sustainability of agricultural systems is under scrutiny in many parts of the world. In the European Union farming systems are increasingly subject to legislation aimed at controlling production or the environment. Against this background a wide range of research is being undertaken into new or alternative land use systems. In this paper it is argued that sustainability in effect provides parameters for this process of change. Therefore, one of the roles of researchers is to high light the options for change available to farmers and to suggest to policy makers the likelihood and ways of improving the uptake of desirable farming practices. Examples are drawn from a variety of research being undertaken in Agricultural Systems at the University of Reading. It is concluded that a systems approach must be an integral part of progress towards increasingly sustainable farming practices and to achieve this agricultural universities must maintain a strong systems research and teaching commitment.

South Korea, China, and Japan are three dominant countries in the global shipbuilding industry, and the competition between them has become more complex over time. The International Maritime Organization environmental regulations and the wave of Industry 4.0 have made the global shipbuilding industry more technology intensive than before. However, after the financial crisis of 2008, China's labor-intensive strategy outperformed the technology-intensive competitive strategy adopted by Japan and South Korea, and China was ranked first with the largest market share. This study sets out to explore whether China's labor-intensive strategy will remain superior to the technology-intensive one of Japan and South Korea. Specifically, we investigate how competitive relationships between the three countries changed after the 2008 global financial crisis. We also forecast how many ships each country will complete in through 2026. To analyze this dynamic competitive system, we use the three-dimensional Lotka-Volterra model, drawing on annual data reporting the number of ships built. The findings suggest that China has gained a competitive advantage over Japan since the 2008 global financial crisis, while South Korea has maintained a mutualistic relationship with both Japan and China. Our forecast suggests that China may lose its competitive advantage in the near future, if China does not embrace a more technology-intensive approach.

This study explores whether teenagers` traditional media use time has been affected by smartphone use time. Drawing on the Korean Media Panel Survey from 2011 to 2014, we specify two models-a two-stage least squares (2SLS) and a two-stage least squares with individual fixed effects (2SLS-FE)- and compare the estimates. The estimates from the 2SLS model show that teenagers` smartphone use time has a substitution effect on book reading time, computer use time, and TV watching time, while the estimates from the 2SLSFE model show that teenagers` smartphone use time has a substitution effect on teenagers` book reading time and computer use time but no significant effect on their TV watching time.

This study explains the competitive diffusion of nuclear energy and nonnuclear energy, adopting the Lotka-Volterra model of nonlinear dynamics to do so. In this paper, the competitive relationship in the energy diffusion process is treated as a competitive ecosystem in which nuclear energy as an emerging species competes with existing nonnuclear energy. We analyze installed capacity data of each energy source from 1978 to 2012. Using estimated Lotka-Volterra models, we investigate what kind of competitive relationship obtained between nuclear and nonnuclear power in the energy policies of every South Korean government from 1982 to 2012. The result shows that mutualism has largely characterized energy diffusion in Korea. That is, nuclear energy and nonnuclear energy stood in a win-win relationship to each other most of the time, promoting the proliferation of each other in the diffusion process. Between 1988 and 1991, in 1997, and then again 2008, the relationship between the two was a predatorprey one: nuclear energy as a predator inhibited the diffusion of nonnuclear energy as a prey in the diffusion process. This result implies the path dependency of the energy policy in Korea. Taking the current competitive environment as our cue, we forecast the future diffusion scenario using an equilibrium analysis and a numerical simulation. The forecast shows that the proportion of installed nuclear capacity in 2030 will reach to 23.8% of total energy sources, which is about 5% below the energy policy goal set by the Park Keun-hye government recently.