Late Devonian and Early Mississippian Distal Basin-Margin Sedimentation of Northern Ohio

Author Institution: Department of Geological Sciences, Cleveland State UniversityClastic sediments, derived from southeastern, eastern and northeastern sources, prograded westward into a shallow basin at the northwestern margin of the Appalachian Basin in Late Devonian and Early Mississippian time. The western and northwestern boundary of the basin was the submerged Cincinnati Arch. The marine clastic wedges provided a northwest paleoslope and a distal, gentle shelf-edge margin that controlled directional emplacement of coarse elastics. Rising sea levels coupled with differences in sedimentation rates and localized soft-sediment deformation within the basin help explain some features of the Bedford and Berea Formations. The presence of sand-filled mudcracks and flat-topped symmetrical ripple marks in the Berea Formation attest to very shallow water deposition and local subaerial exposure at the time of emplacement of part of the formation. Absence of thick, channel-form deposits eastward suggests loss of section during emergence

Integration of ethics into a forestry curriculum

Following a comprehensive review of their forestry curriculum in 1995, the Oklahoma State University Forestry Faculty elected to modify the way professional ethics are formally addressed. The modifications involve three courses. An introduction of ethics and their role in natural resource management is presented to freshman in an introductory course. This provides a framework for learning and applying the science and practices of the Forestry Profession in the context of an ethical philosophy. Students address ethics a second time between their sophomore and junior years. This happens during the initial summer camp course where students are exposed to philosophical and policy differences between natural resource management agencies. Ethics are formally reintroduced in two senior courses that are usually taken concurrently. One of these courses is a capstone experience where students address real natural resource management problems. The second is a course in forest administration and natural resource policy. In these two courses the instructors cooperate to require the students to consider professional ethics in a philosophical framework for decision making as well as an applied standard for real decisions in the execution of professional work. This is accomplished through discussions of the Ethical Canons of the Society of American Foresters in the forest administration and policy course. These discussions are followed by group presentations to the class of ethical considerations associated with projects from the student’s capstone experience

Bioresorbable Polylactide Interbody Implants in an Ovine Anterior Cervical Discectomy and Fusion Model: Three-Year Results

Study Design. In vivo study of anterior discectomy and fusion using a bioresorbable 70:30 poly(l-lactide-co-d,l-lactide) interbody implant in an ovine model. Objective. To evaluate the efficacy of the polylactide implant to function as an interbody fusion device, and to assess the tissue reaction to the material during the resorption process. Summary of Background Data. The use of polylactide as a cervical interbody implant has several potential advantages when compared with traditional materials. Having an elastic modulus very similar to bone minimizes the potential for stress shielding, and as the material resorbs additional loading is transferred to the developing fusion mass. Although preclinical and clinical studies have demonstrated the suitability of polylactide implants for lumbar interbody fusion, detailed information on cervical anterior cervical discectomy and fusion (ACDF) with polylactide devices is desirable. Methods. Single level ACDF was performed in 8 skeletally mature ewes. Bioresorbable 70:30 poly (l-lactide-co-d,l-lactide) interbody implants packed with autograft were used with single-level metallic plates. Radiographs were made every 3 months up to 1 year, and yearly thereafter. The animals were killed at 6 months (3 animals), 12 months (3 animals), and 36 months (2 animals). In addition to the serial plain radiographs, the specimens were evaluated by nondestructive biomechanical testing and undecalcified histologic analysis. Results. The bioresorbable polylactide implants were effective in achieving interbody fusion. The 6-month animals appeared fused radiographically and biomechanically, whereas histologic sections demonstrated partial fusion (in 3 of 3 animals). Radiographic fusion was confirmed histologically and biomechanically at 12 months (3 of 3 animals) and 36 months (2 of 2 animals). A mild chronic inflammatory response to the resorbing polylactide implant was observed at both 6 months and 12 months. At 36 months, the operative levels were solidly fused and the implants were completely resorbed. No adverse tissue response was observed in any animal at any time period. Conclusion. Interbody fusion was achieved using bioresorbable polylactide implants, with no evidence of implant collapse, extrusion, or adverse tissue response to the material. The use of polylactide as a cervical interbody device appears both safe and effective based on these ACDF animal model results