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In summary, distraction osteogenesis is a safe and effective means of achieving bone lengthening. These techniques were originally applied to the long bones of the extremities; over the past 10 years they have been effectively applied to the bones of the craniofacial skeleton. The new bone regenerate that is observed after distraction osteogenesis is stable, and relapse rates after skeletal advancement are believed to be lower than with conventional osteotomy and bone graft techniques. There is considerable variability in distraction protocols employed in clinical practice, including differences in the types of devices used and in the rate, rhythm, latency, and period of consolidation for distraction osteogenesis. The greatest application for distraction osteogenesis in the craniofacial skeleton has been with mandible lengthening, for which there is presently a 10-year clinical experience. Midfacial advancement is a newer application of distraction osteogenesis, for which clinical experience has been accrued over the past 5 years. This latter experience indicates that distraction osteogenesis is a viable treatment option for lengthening of the hypoplastic mandible and midface. These techniques have advantages over conventional means of bone graft and rigid fixation because of the quality of the bone regenerate, the decrease in the long-term relapse rate of the advanced bone segments in both the mandible and the midface, and the simultaneous soft-tissue elongation that accompanies the distraction process. Distraction osteogenesis is particularly applicable to the correction of severe deformities of the mandible and midface in children with developmental hypoplasia and syndromic craniosynostosis. However, growth is an added variable in this patient population. The amount of overcorrection in lengthening of the hypoplastic bone required to compensate for continued growth discrepancy of the adjacent facial bones is difficult to predict. Therefore, the families of these patients should be informed that many children will require repeated operations at a later age as they reach skeletal maturity.  相似文献   
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A recently released National Research Council (NRC) report, Learning and Understanding: Improving Advanced Study of Mathematics and Science in U.S. High Schools, evaluated and recommended changes in the Advanced Placement (AP), International Baccalaureate (IB), and other advanced secondary school science programs. As part of this study, discipline-specific panels were formed to evaluate advanced programs in biology, chemistry, physics, and mathematics. Among the conclusions of the Content Panel for Biology were that AP courses in particular suffer from inadequate quality control as well as excessive pressure to fulfill their advanced placement function, which encourages teachers to attempt coverage of all areas of biology and emphasize memorization of facts rather than in-depth understanding. In this essay, the Panel's principal findings are discussed, with an emphasis on its recommendation that colleges and universities should be strongly discouraged from using performance on either the AP examination or the IB examination as the sole basis for automatic placement out of required introductory courses for biology majors and distribution requirements for nonmajors.  相似文献   
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Routinely collected health data, obtained for administrative and clinical purposes without specific a priori research goals, are increasingly used for research. The rapid evolution and availability of these data have revealed issues not addressed by existing reporting guidelines, such as Strengthening the Reporting of Observational Studies in Epidemiology (STROBE). The REporting of studies Conducted using Observational Routinely collected health Data (RECORD) statement was created to fill these gaps. RECORD was created as an extension to the STROBE statement to address reporting items specific to observational studies using routinely collected health data. RECORD consists of a checklist of 13 items related to the title, abstract, introduction, methods, results, and discussion section of articles, and other information required for inclusion in such research reports. This document contains the checklist and explanatory and elaboration information to enhance the use of the checklist. Examples of good reporting for each RECORD checklist item are also included herein. This document, as well as the accompanying website and message board (http://www.record-statement.org), will enhance the implementation and understanding of RECORD. Through implementation of RECORD, authors, journals editors, and peer reviewers can encourage transparency of research reporting.  相似文献   
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