Computationally Efficient Finite Element Models of the Lumbar Spine for the Evaluation of Spine Mechanics and Device Performance

Finite Element models of the lumbar spine are commonly used for the study of spine mechanics and device performance, but have limited usefulness in some applications such as clinical and design phase assessments due to long analysis times. In this study a computationally efficient L4-L5 FSU model and a L1-Sacrum multi-segment model were developed and validated. The FSU is a functional spine unit consisting of two adjacent vertebral bodies, in this case L4 and L5. The multi-segment model consists of all lumbar vertebrae and the sacrum. The models are able to accurately predict spine kinematics with significantly reduced analysis times, relative to fully deformable representations. Analysis times were reduced from 3 hrs and 20 min to 2 min and 1 min for the multi-segment and FSU models, respectively. The vertebrae geometries were reconstructed from CT scans of the cadaveric specimen. Prior to model development, experimental testing was performed on the specimen using a custom multi-axis spine simulator. Collection of kinematic data in response to external loading made tuning of the model stiffness possible. The improved computational efficiency of the models makes them more useful for applications requiring multiple iterations and short analysis times such as clinical and design phase assessments of implants. The model can also be used in efforts to develop lumbar musculoskeletal models, which may require multiple runs for the optimization of muscle forces

Impact of Hall effect on energy decay in magnetohydrodynamic turbulence

We examine numerically the influence of Hall effect corrections to Ohm's law upon the decay of homogeneous compressible magnetohydrodynamic turbulence and conclude that there are no significant differences in global decay rate associated with the Hall effect. This affirms expectations that energy decay is controlled by the large-scale eddies

Is the Cepheus E Outflow driven by a Class 0 Protostar?

New early release observations of the Cepheus E outflow and its embedded source, obtained with the Spitzer Space Telescope, are presented. We show the driving source is detected in all 4 IRAC bands, which suggests that traditional Class 0 classification, although essentially correct, needs to accommodate the new high sensitivity infrared arrays and their ability to detected deeply embedded sources. The IRAC, MIPS 24 and 70 microns new photometric points are consistent with a spectral energy distribution dominated by a cold, dense envelope surrounding the protostar. The Cep E outflow, unlike its more famous cousin the HH 46/47 outflow, displays a very similar morphology in the near and mid-infrared wavelengths, and is detected at 24 microns. The interface between the dense molecular gas (where Cep E lies) and less dense interstellar medium, is well traced by the emission at 8 and 24 microns, and is one of the most exotic features of the new IRAC and MIPS images. IRS observations of the North lobe of the flow confirm that most of the emission is due to the excitation of pure H2 rotational transitions arising from a relatively cold (Tex~700 K) and dense (N{H}~9.6E20 cm-2 molecular gas.Comment: 14 pages (pre-print format), including 6 figures. Published in ApJ Special Spitzer Issue (2004

Heating the outer heliosphere by pickup protons

There is a growing body of literature that demonstrates the ability of a turbulent cascade within the solar wind to heat the thermal protons. Several sources of energy are required to accomplish the observed heating. Wind shear and shocks originating with the multiple source of wind plasma heat the wind inside ∽AU. However, beyond this distance little is left of these sources and all that remains is the energy injected into the plasma by the pickup of newborn protons originating from interstellar neutrals. Recent advances in the theory of wave excitation by the newborn protons allows us to return to the published heating theory and remove a previously unexplained parameterization of the heating due to pickup protons. Furthermore, recent observational evidence suggests that large-scale correlations between the wind speed and the proton temperature exist into the distant outer heliosphere that motivate an attempt to connect the two within the structure of the heating theory

Enhanced Capacitative Calcium Entry and Sarcoplasmic-Reticulum Calcium Storage Capacity with Advanced Age in Murine Mesenteric Arterial Smooth Muscle Cells

Intracellular Ca(2+) signaling is important to perfusion pressure related arterial reactivity and to vascular disorders including hypertension, angina and ischemic stroke. We have recently shown that advancing-age leads to calcium signaling adaptations in mesenteric arterial myocytes from C57 BL/6 mice [Corsso, C.D., Ostrovskaya. O., McAllister, C.E., Murray, K., Hatton, W.J., Gurney, A.M., Spencer, N.J., Wilson, S.M., 2006. Effects of aging on Ca(2+) signaling in murine mesenteric arterial smooth muscle cells. Mech. Ageing Dev. 127, 315-323)] which may contribute to decrements in perfusion pressure related arterial contractility others have shown occur. Even still, the mechanisms underlying the changes in Ca(2+) signaling and arterial reactivity are unresolved. Ca(2+) transport and storage capabilities are thought to contribute to age-related Ca(2+) signaling dysfunctions in other cell types. The present studies were therefore designed to test the hypothesis that cytosolic and compartmental Ca(2+) homeostasis in mesenteric arterial myocytes changes with advanced age. The hypothesis was tested by performing digitalized fluorescence microscopy on mesenteric arterial myocytes isolated from 5- to 6-month and 29- to 30-month-old C57BI/6 mice. The data provide evidence that with advanced age capacitative Ca(2+) entry and sarcoplasmic reticulum Ca(2+) storage are increased although sarcoplasmic reticulum Ca(2+) uptake and plasma membrane Ca(2+) extrusion are unaltered. Overall, the studies begin to resolve the mechanisms associated with age-related alterations in mesenteric arterial smooth muscle Ca(2+) signaling and their physiological consequences. (C) 2008 Elsevier Inc. All rights reserved

The Scaled Arrival of K-12 Online Education: Emerging Realities and Implications for the Future of Education

Bioinfo PublicationsDramatic increases in K—12 online education for all students, including those in traditionally underserved populations, necessi2 tate a reconceptualization in the way educators plan and implement instruction. In this article the authors examine the complex array of variables and implementation models that must be accounted for during the pivot from a purely brick-and-mortar educational sys2 tem to one that makes use of both virtual and blended environ2 ments. The authors call for enhanced emphasis on instructional goals and design principles, rather than the capabilities of available technology. They conclude that educational leaders and researchers must play a role in three key areas: using technology to enhance the accessibility and usability of curricular materials to meet the needs of different types of learners, advancing the understanding and practices of in-service and pre-service teachers through preparation that focuses on online learning, and fostering collaboration between educational researchers and technology innovators and developers to build a research base that will inform K—12 online education

The Effectiveness of Grade 5 Mobilizations vs. Grade 1-4 Mobilizations on Mechanical Neck Pain: A Clinically Appraised Topic

• From 2000 to 2010, mechanical neck pain (MNP) prevalence ranged from 30% to 50% in adults. Other data suggests that 46% to 54% of every adult will experience some form of neck pain during their lives. • Non-thrust mobilizations (NTM) and Thrust mobilizations (TM) are among the common interventions used in manual therapy in treatment of MNP. • The evidence accumulated for this clinically appraised topic (CAT) suggests high clinical variability among the effectiveness in NTM and TM among adults with mechanical neck pain

Monocot fossils suitable for molecular dating analyses

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/111920/1/boj12233.pd