Material and Structural Aspects of Bone in Osteogenesis Imperfecta

Bone fragility is a fundamental problem in individuals with osteogenesis imperfecta (OI). The mechanisms behind this fragility, however, are not yet well understood. Multiple factors appear to contribute to the increased fracture risk in OI. At the structural level, bone mass deficiency can result in increased stress levels within bones. The underlying mineral and collagen abnormalities that define OI are also believed to result in compromised material-level properties. The variability of collagen biochemical irregularities causing OI and the corresponding heterogeneity of disease severity result in abnormalities that are not easily generalized within the OI population. The aims of this chapter are to introduce basic mechanical notions pertaining to the strength of structures and materials, and to present a synthesis of existing literature regarding the mechanical properties of bones in OI

Brown dwarf populations in open clusters

We present the results of multiple simulations of open clusters, modelling the dynamics of a population of brown dwarf members. We consider the effects of a large range of primordial binary populations, including the possibilities of having brown dwarf members contained within a binary system. We also examine the effects of various cluster diameters and masses. Our examination of a population of wide binary systems containing brown dwarfs, reveals evidence for exchange reactions whereby the brown dwarf is ejected from the system and replaced by a heavier main-sequence star. We find that there exists the possibility of hiding a large fraction of the brown dwarfs contained within the primordial binary population. We conclude that it is probable that the majority of brown dwarfs are contained within primordial binary systems which then hides a large proportion of them from detection.Comment: 16 pages, 8 figures; to appear in MNRA

Mountain States Oilseeds: Risk Management for Safflower Production in the Intermountain West

Safflower is an oilseed crop primarily produced in the western Great Plains because of its compatibility with cereal grain equipment. Varieties grown in that region are harvested predominantly for seeds high in safflower oil and oleic acid that are processed and used in cooking oil, human nutrition, and other health and beauty products. Safflower is also grown in Utah, Idaho, and California for birdseed mixes due to the region’s arid climate, which yields a crisp, white seed that is highly favorable in the birdseed market. Mountain States Oilseeds, headquartered in American Falls, Idaho, is one of the United States’ largest processors of safflower seed and is the nation’s No. 1 supplier of safflower seed used in birdseed mixes. While increasing demand for oilseeds will bolster Mountain States Oilseeds’ business, producers often view safflower as a minor annual crop with a high-risk profile and minimal expected returns. Thus, Mountain States Oilseeds must develop a strategy to entice more dedicated oilseed production as resource constraints tighten across the Western U.S. and the worldwide demand for safflower oil, birdseed, and meal continues to expand

Micro-CT Characterization of Human Trabecular Bone in Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a genetic syndrome affecting collagen synthesis and assembly. Its symptoms vary widely but commonly include bone fragility, reduced stature, and bone deformity. Because of the small size and paucity of human specimens, there is a lack of biomechanical data for OI bone. Most literature has focused on histomorphometric analyses, which rely on assumptions to extrapolate 3-D properties. In this study, a micro-computed tomography (μCT) system was used to directly measure structural and mineral properties in pediatric OI bone collected during routine surgical procedures. Surface renderings suggested a poorly organized, plate-like orientation. Patients with a history of bone-augmenting drugs exhibited increased bone volume fraction (BV/TV), trabecular number (Tb.N), and connectivity density (Eu.Conn.D). The latter two parameters appeared to be related to OI severity. Structural results were consistently higher than those reported in a previous histomorphometric study, but these differences can be attributed to factors such as specimen collection site, drug therapy, and assumptions associated with histomorphometry. Mineral testing revealed strong correlations with several structural parameters, highlighting the importance of a dual approach in trabecular bone testing. This study reports some of the first quantitative μCT data of human OI bone, and it suggests compelling possibilities for the future of OI bone assessment

Ideologies of time: How elite corporate actors engage the future

Our paper deals with how elite corporate actors in a Western capitalist-democratic society conceive of and prepare for the future. Paying attention to how senior officers of ten important Danish companies make sense of the future will help us to identify how particular temporal narratives are ideologically marked. This ideological dimension offers a common sense frame that is structured around a perceived inevitability of capitalism, a market economy as the basic organizational structure of the social and economic order, and an assumption of confident access to the future. Managers envisage their organization?s future and make plans for organizational action in a space where ?business as usual? reigns, and there is little engagement with the future as fundamentally open; as a time-yet-to-come. In using a conceptual lens inspired by the work of Fredric Jameson, we first explore the details of this presentism and a particular colonization of the future, and then linger over small disruptions in the narratives of our interviewees which point to what escapes or jars their common sense frame, explore the implicit meanings they assign to their agency, and also find clues and traces of temporal actions and strategies in their narratives that point to a subtly different engagement with time

Putting into Question the Imaginary of Recovery: A Dialectical Reading of the Global Financial Crisis and its Aftermath

In this article we put into question the discourses that emerged during the Global Financial Crisis (GFC) and that coalesced around a particular socio-economic imaginary of ?recovery? over the period 2009-2012. Our reading of these discourses is very much guided by the notion of the dialectic as developed by Fredric Jameson, and as such this paper can be read as attempt to put his theoretical ideas to work. Through our dialectical reading we aim to create a certain estrangement effect that makes the imaginary of recovery seem very odd and unnatural. In order to achieve such an effect we postulate four theses which are deliberately antagonistic: first, that there has been no ?crisis of capitalism?; second, that we must change the valence of the GFC from negative to positive; third, that the relationship between finance capitalism and ?free markets? is deeply contradictory; and fourth, that we must resist the regulation discourse

Design and Validation of Bending Test Method for Characterization of Miniature Pediatric Cortical Bone Specimens

Osteogenesis imperfecta is a genetic disorder of bone fragility; however, the effects of this disorder on bone material properties are not well understood. No study has yet measured bone material strength in humans with osteogenesis imperfecta. Small bone specimens are often extracted during routine fracture surgeries in children with osteogenesis imperfecta. These specimens could provide valuable insight into the effects of osteogenesis imperfecta on bone material strength; however, their small size poses a challenge to their mechanical characterization. In this study, a validated miniature three-point bending test is described that enables measurement of the flexural material properties of pediatric cortical osteotomy specimens as small as 5 mm in length. This method was validated extensively using bovine bone, and the effect of span/depth aspect ratio (5 vs 6) on the measured flexural properties was examined. The method provided reasonable results for both Young’s modulus and flexural strength in bovine bone. With a span/depth ratio of 6, the median longitudinal modulus and flexural strength results were 16.1 (range: 14.4–19.3) GPa and 251 (range: 219–293) MPa, respectively. Finally, the pilot results from two osteotomy specimens from children with osteogenesis imperfecta are presented. These results provide the first measures of bone material strength in this patient population