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ABSTRACT IMPACT: This study will answer key questions that spine surgeons have regarding techniques used in cement augmentation of vertebral compression fractures and will ultimately advance patient care for such injuries. OBJECTIVES/GOALS: The objective of this study is to determine if a difference exists in load-bearing characteristics and load-to-fracture between injecting cement anteriorly prior to screw placement versus cement augmentation via fenestrated pedicle screws. We also expect differences in load-to-failure characteristics between different cement volumes. METHODS/STUDY POPULATION: This study will be performed in a bioengineering laboratory that has access to a Materials Testing System (MTS). Eight cadaveric specimens will be selected from our stock after pre-screening via CT for inclusion and exclusion criteria. The levels T8-L1 will be dissected from the vertebral column along with any soft tissue structures. The vertebral bodies will be potted in an epoxy mold. From each spine, there are 2 groups of three. One vertebral body from each spine will serve as an internal control, one will be augmented with cement via a cannula and then instrumented with a non-fenestrated screw and the third will be instrumented will a fenestrated screw and then augmented with cement. After appropriate curing time, repeat CT imaging will be completed. The specimens will then be loaded to failure and the results analyzed. RESULTS/ANTICIPATED RESULTS: We hypothesize that we will see a better anterior spread with the cannula/non-fenestrated screw method as compared to the fenestrated screw. The reason being is that we would expect the fenestrated screw to experience more cement extruding from the fenestration rather than being directed anteriorly. We believe a better anterior spread of the cement will lead to a greater load-bearing capacity for the vertebral body. We also believe that a difference will exist in load-to-failure testing with the two volumes being tested, though we cannot predict to what a degree this difference will be impactful as there have been few studies prior looking at this. DISCUSSION/SIGNIFICANCE OF FINDINGS: This study is significant because it will aid in determining the optimal technique to implement in the setting of vertebral compression fractures. This will lead to improved patient care as well as a greater understanding of the instrumentation used in such procedures. The results will lay the groundwork for future research on this procedure.
Item response theory has its origins in educational measurement and is now commonly applied in health-related measurement of latent traits, such as function and symptoms. This application is due, in large part, to gains in the precision of measurement attributable to item response theory and corresponding decreases in response burden, study costs, and study duration. The purpose of this paper is twofold: introduce basic concepts of item response theory and demonstrate this analytic approach in a worked example, a Rasch model (1PL) analysis of the Eating Assessment Tool (EAT-10), a commonly used measure for oropharyngeal dysphagia. The results of the analysis were largely concordant with previous studies of the EAT-10 and illustrate for brain impairment clinicians and researchers how IRT analysis can yield greater precision of measurement.
This paper aims to situate functional abstraction in light of systems thinking. While function does not extensively appear in systems thinking literature, the literature does identify function as part of systems thinking that enables us to recognize and connect that function has a role in building a systems thinking approach for students. A systems thinking approach is valuable for students since it helps them view a system holistically. In this research, we measure how well students are able to abstract function. We asked students to generate functions for two different products and examined how students taught functional modeling and function enumeration compare to students who are only taught function enumeration. The student responses were examined using a rubric that we developed and validated for assessing function. This rubric may be used to classify functions by correctness (correct, partially correct, and incorrect) and categories (high level, interface, low level, and ambiguous). On questions where students were not explicitly asked to write a high-level function or low-level function, and so on, students who were taught functional modeling were able to better demonstrate systems thinking in their responses (low-level and interface functions) than those students who were only taught function enumeration.
This study uses an experiment where ferry passengers are sold hotel room “views” to evaluate the impact of wind turbines views on tourists’ vacation experience. Participants purchase a chance for a weekend hotel stay. Information about the hotel rooms was limited to the quality of the hotel and its distance from a large wind turbine, as well as whether or not a particular room would have a view of the turbine. While there was generally a negative effect of turbine views, this did not hold across all participants, and did not seem to be effected by distance or hotel quality.
New commercial aero engines for 2050 are expected to have lower specific thrusts for reduced noise and improved propulsive efficiency, but meeting the ACARE Flightpath 2050 fuel-burn and emissions targets will also need radical design changes to improve core thermal efficiency. Intercooling, recuperation, inter-turbine combustion and added topping and bottoming cycles all have the potential to improve thermal efficiency. However, these new technologies tend to increase core specific power and reduce core mass flow, giving smaller and less efficient core components. Turbine cooling also gets more difficult as engine cores get smaller. The core-size-dependent performance penalties will become increasingly significant with the development of more aerodynamically efficient and lighter-weight aircraft having lower thrust requirements. In this study the effects of engine thrust and core size on performance are investigated for conventional and intercooled aeroengine cycles. Large intercooled engines could have 3%–4% SFC improvement relative to conventional cycle engines, while smaller engines may only realize half of this benefit. The study provides a foundation for investigations of more complex cycles in the EU Horizon 2020 ULTIMATE programme.
Electoral forensics involves examining election results for anomalies to efficiently identify patterns indicative of electoral irregularities. However, there is disagreement about which, if any, forensics tool is most effective at identifying fraud, and there is no method for integrating multiple tools. Moreover, forensic efforts have failed to systematically take advantage of country-specific details that might aid in diagnosing fraud. We deploy a Bayesian additive regression trees (BART) model–a machine-learning technique–on a large cross-national data set to explore the dense network of potential relationships between various forensic indicators of anomalies and electoral fraud risk factors, on the one hand, and the likelihood of fraud, on the other. This approach allows us to arbitrate between the relative importance of different forensic and contextual features for identifying electoral fraud and results in a diagnostic tool that can be relatively easily implemented in cross-national research.
Here, we report reproducible and accurate measurement of crystallographic parameters using scanning transmission electron microscopy. This is made possible by removing drift and residual scan distortion. We demonstrate real-space lattice parameter measurements with <0.1% error for complex-layered chalcogenides Bi2Te3, Bi2Se3, and a Bi2Te2.7Se0.3 nanostructured alloy. Pairing the technique with atomic resolution spectroscopy, we connect local structure with chemistry and bonding. Combining these results with density functional theory, we show that the incorporation of Se into Bi2Te3 causes charge redistribution that anomalously increases the van der Waals gap between building blocks of the layered structure. The results show that atomic resolution imaging with electrons can accurately and robustly quantify crystallography at the nanoscale.
We report evidence for graphene layer rearrangements in heavy ion interactions with carbon onions at 140 MeV and 70 MeV per nucleon kinetic energies. Graphene layer rearrangements have been recently predicted in spherical and cylindrical multi-layer graphene systems. The implications of graphene layer rearrangement on the tribological performance of multi-layer nano-carbons in extreme environments are discussed.
Saproxylic insect assemblages inhabiting dead wood in Canadian forests are highly diverse and variable but quite poorly understood. Adequate assessment of these assemblages poses significant challenges with respect to sampling, taxonomy, and analysis. Their assessment is nonetheless critical to attaining the broad goals of sustainable forest management because such species are disproportionately threatened elsewhere by the reductions in dead wood generally associated with commercial exploitation of northern forests. The composition of the saproxylic fauna is influenced by many factors, including tree species, degree of decay, stand age, and cause of tree death. Wildfire and forest harvesting have differential impacts on saproxylic insect assemblages and on their recovery in postdisturbance stands. Exploration of saproxylic insect responses to variable retention harvesting and experimental burns is contributing to the development of prescriptions for conserving saproxylic insects in boreal forests. Understanding of processes that determine diversity patterns and responses of saproxylic insects would benefit from increased attention to natural history. Such work should aim to provide a habitat-classification system for dead wood to better identify habitats (and associated species) at risk as a result of forest management. This tool could also be used to improve strategies to better maintain saproxylic organisms and their central nutrient-cycling functions in managed forests.
The Canadian insect fauna is too inadequately understood to support well-informed assessments about its conservation status; however, the foregoing collection of synthetic papers illustrates potential threats from industrial forestry. Loss of forest species and dramatic changes in forest insect assemblages driven by forestry activities are well illustrated by studies from places where industrial forest management has been more intensive or of longer duration. Improved understanding of how arthropod species are coupled to habitats, especially microhabitats, appears to be central to progress toward their conservation. Studies of arthropods conducted at the species level are most relevant for applied conservation purposes, because only species-level work that is well documented with voucher specimens provides adequate comparative data to document faunal change. Although taxonomic infrastructure required to support such work is seriously under-resourced in Canada, entomologists can help themselves by producing useful modern resources for species identification, by undertaking collaborative biodiversity work that minimizes the split between taxonomists and ecologists, and by supporting incentives for work at the species level. Securing the future of arthropod diversity in Canadian forests through effective policy will require sound regionally defined bases for whole-fauna conservation that mesh with broader land-use planning. Building these will require a practical understanding of how “ecosite”-classification systems relate to arthropod diversity, accurate inventories of the predisturbance forest fauna in all regions, and development of sound monitoring plans designed to both detect faunal change efficiently and identify its drivers. Such monitoring plans should include both baseline inventories and monitoring of designated control areas. In addition, effective biomonitoring efforts will facilitate the development of suites of arthropod indicators, accommodate both seasonal (especially phenological) and annual variation, clarify the relationship between cost-effective samples and reality, and ensure adequate consideration of “rare” species. Return on investment in monitoring will depend on effective preplanned linkage to policy development that can respond to drivers of faunal change in a way that effectively addresses undesired changes.
In philosophical circles such as ours, we have become accustomed to expressing our religious ideas, and offering our analyses and arguments regarding these ideas, in terms that are associated with what we call “theism.” I take this usage to be a convenient abbreviation. Perhaps we should better characterize the terms that we like to use and the concepts with which we operate as belonging to “monotheistic” discourse, rather than as simply being “theistic.” Moreover it should be noted that our discussions almost invariably relate to monotheism of a very specific type, such as the type that has become foundational in all the current religious traditions which are the successors of the Hebrew scriptures, namely, Christianity, Islam, and Judaism. Because this is so, there are two things that we shall do well to take into consideration. First of all, we must note that the theological discussions within these three great historical traditions have sometimes been more inclusive and of wider range than what is just contained in these simple monotheistic terms, no matter how foundational these terms may be. Each of the traditions has included philosophical currents and mystical movements that have modified, in different ways, the basic concepts behind the skeletal monotheistic terms with which they have operated. Of this we shall speak more later on. Second, we must recognize that when, in the course of our philosophic discussions, we do formulate our ideas in the simple monotheistic terms, as these are understood by the ordinary believers within those religious traditions, we do so at a cost.
MAP30 is a 30 kDa single-stranded, type-I ribosome
inactivating protein (RIP) possessing anti-tumor and anti-HIV
activities. It binds both ribosomal RNA and the HIV-1 long-terminal
repeat DNA. To understand the structural basis for MAP30
activities, we undertook the study of MAP30 by solution
NMR spectroscopy. We report nearly complete 1H,
13C, and 15N chemical shift assignments
of its 263 amino acids. Based upon an analysis of secondary
13C chemical shifts, 3JHNHA
coupling constants, hydrogen exchange data, and nuclear
Overhauser effect patterns, we find that the secondary
structure and β-sheet topology of MAP30 are very similar
to those of the ricin A chain, a subunit of the well-known
type-II RIP, even though two proteins display distinct
activities. We therefore suggest that MAP30 and ricin A
chain share a similar three-dimensional fold, and that
the reported functional differences between two proteins
arise primarily from differences in local three-dimensional
structure and other structural properties such as surface
The Digital Micromirror Device™ (DMD™) developed at Texas Instruments is a spatial light modulator composed of 500,000 to 1.3 million movable micromachined aluminum mirrors. The DMD™ serves as the engine for the current generation of computer-driven slide and video projectors, and for next generation devices in digital television and movie projectors. The unique architecture and applications of the device present several packaging and test challenges. This paper provides a description of package humidity modeling and verification testing, as well as an overview of the automated optical testing and test equipment that have been developed to support manufacturing of the DMD™.
Bone loss (osteolysis) following total joint arthroplasty has been a subject of increasing concern in the orthopedic research community. Depending on the distribution and severity, bone loss can lead to aseptic loosening, periprosthetic fracture and formidable reconstructive problems at revision surgery. Bone loss is believed to be primarily a response to particulate wear and corrosion debris derived from the prosthetic materials. Phagocytosed particulates activate macrophages and osteoblasts (and perhaps fibroblasts) to produce factors which stimulate osteoclastic bone resorption and reduce osteoblastic bone formation. To investigate the responses of these cells to particulate corrosion and wear debris, in vitro studies have been performed by measuring factors at both the molecular and cellular levels that may trigger, maintain and/or regulate particulate biomaterial-induced pathologic bone resorption. The biological effect of a particulate species depends upon their size, concentration (number) and composition, in the order listed. Particulate wear debris of phagocytosable size (less that 10 micrometers) activate macrophages, fibroblasts and osteoblasts more effectively that those of larger sizes. As a response to phagocytosed particulates, i) macrophages produce a number of cytokines (interleukins such as II-1, II-6, TNF-alpha) and prostaglandins, which may act either in an autocrine fashion or further stimulate cells present in the periprosthetic tissue; ii) fibroblasts secrete active forms of metalloproteinases; and iii) osteoblasts have diminished collagen type I synthesis. Taken together, particulate corrosion and wear debris provoke a series of biological responses which generate an active microenvironment around prosthetic components. Strategies to modify the host response to particulate degradation products have emerged from these in vitro studies. These strategies may provide pharmacotherapeutic solutions to this important clinical problem.