Local origins impart conserved bone type-related differences in human osteoblast behaviour

Osteogenic behaviour of osteoblasts from trabecular, cortical and subchondral bone were examined to determine any bone type-selective differences in samples from both osteoarthritic (OA) and osteoporotic (OP) patients. Cell growth, differentiation; alkaline phosphatase (TNAP) mRNA and activity, Runt-related transcription factor-2 (RUNX2), SP7-transcription factor (SP7), bone sialoprotein-II (BSP-II), osteocalcin/bone gamma-carboxyglutamate (BGLAP), osteoprotegerin (OPG, TNFRSF11B), receptor activator of nuclear factor-κβ ligand (RANKL, TNFSF11) mRNA levels and proangiogenic vascular endothelial growth factor-A (VEGF-A) mRNA and protein release were assessed in osteoblasts from paired humeral head samples from age-matched, human OA/OP (n = 5/4) patients. Initial outgrowth and increase in cell number were significantly faster (p < 0.01) in subchondral and cortical than trabecular osteoblasts, in OA and OP, and this bone type-related differences were conserved despite consistently faster growth in OA. RUNX2/SP7 levels and TNAP mRNA and protein activity were, however, greater in trabecular than subchondral and cortical osteoblasts in OA and OP. BSP-II levels were significantly greater in trabecular and lowest in cortical osteoblasts in both OA and OP. In contrast, BGLAP levels showed divergent bone type-selective behaviour; highest in osteoblasts from subchondral origins in OA and trabecular origins in OP. We found virtually identical bone type-related differences, however, in TNFRSF11B:TNFSF11 in OA and OP, consistent with greater potential for paracrine effects on osteoclasts in trabecular osteoblasts. Subchondral osteoblasts (OA) exhibited highest VEGF-A mRNA levels and release. Our data indicate that human osteoblasts in trabecular, subchondral and cortical bone have inherent, programmed diversity, with specific bone type-related differences in growth, differentiation and pro-angiogenic potential in vitro

Fiber-Cavity-Based Optomechanical Device

We describe an optomechanical device consisting of a fiber-based optical cavity containing a silicon nitiride membrane. In comparison with typical free-space cavities, the fiber-cavity's small mode size (10 {\mu}m waist, 80 {\mu}m length) allows the use of smaller, lighter membranes and increases the cavity-membrane linear coupling to 3 GHz/nm and quadratic coupling to 20 GHz/nm^2. This device is also intrinsically fiber-coupled and uses glass ferrules for passive alignment. These improvements will greatly simplify the use of optomechanical systems, particularly in cryogenic settings. At room temperature, we expect these devices to be able to detect the shot noise of radiation pressure.Comment: 4 pages, 3 figures; the following article has been submitted to Applied Physics Letter

A Review of Seismic LRFD (Load-and-Resistance Factor Design) Method for MSE (Mechanically Stabilized Earth) Walls

The introduction of AASHTO’s LRFD (load-and-resistance factor design) method for the design of MSE (mechanically stabilized earth) walls in 2004 has gradually replaced conventional state-of-the-practice seismic ASD (allowable stress design) method in some states, and by FHWA mandate should completely replace the ASD method by 2010. Limit equilibrium analyses based on Mononabe- Okabe (M-O) pseudo-static method had been the standard method of estimating the seismic external thrust and inertia force for MSE walls. Considering the flexible nature of MSE walls that allow deformation without compromising structural integrity, in the LRFD method, the displacement based pseudo-static method that was developed from Newmark sliding block analyses is used. In this paper, parametric studies are used to highlight the variations of soil reinforcement length/wall height ratios and internal lateral stresses between the LRFD and the current state-of-the-practice ASD methods. The results are compared with referenced past experimental studies and recorded seismic field performance of MSE walls. In addition, results from preliminary dynamic constitutive models are provided for comparison with displacements based on M-O pseudo static method. This paper shows that, by selecting an appropriate amount of tolerable wall deformation (i.e. between 25 and 200 mm as specified in AASHTO and FHWA), the seismic LRFD method for MSE walls is conservative and in general is in agreement with the conventional ASD method that has been widely used in the design of the MSE walls that have performed well during past major seismic events

Central dislocation of the hip secondary to insufficiency fracture

We present a case report of a 45-year old man who sustained a central dislocation of the hip secondary to an insufficiency fracture of the acetabulum. At the time of presentation he was on alendronate therapy for osteoporosis which had been previously investigated. CT scanning of the pelvis was useful for pre-operative planning which confirmed collapse of the femoral head but no discontinuity of the pelvis. The femoral head was morcellized and used as bone graft for the acetabular defect and an uncemented total hip replacement was performed

Riparian vegetation, Colorado River, and climate: Five decades of spatiotemporal dynamics in the Grand Canyon with river regulation

Documentation of the interacting effects of river regulation and climate on riparian vegetation has typically been limited to small segments of rivers or focused on individual plant species. We examine spatiotemporal variability in riparian vegetation for the Colorado River in Grand Canyon relative to river regulation and climate, over the five decades since completion of the upstream Glen Canyon Dam in 1963. Long-term changes along this highly modified, large segment of the river provide insights for management of similar riparian ecosystems around the world. We analyze vegetation extent based on maps and imagery from eight dates between 1965 and 2009, coupled with the instantaneous hydrograph for the entire period. Analysis confirms a net increase in vegetated area since completion of the dam. Magnitude and timing of such vegetation changes are river stage-dependent. Vegetation expansion is coincident with inundation frequency changes and is unlikely to occur for time periods when inundation frequency exceeds approximately 5%. Vegetation expansion at lower zones of the riparian area is greater during the periods with lower peak and higher base flows, while vegetation at higher zones couples with precipitation patterns and decreases during drought. Short pulses of high flow, such as the controlled floods of the Colorado River in 1996, 2004, and 2008, do not keep vegetation from expanding onto bare sand habitat. Management intended to promote resilience of riparian vegetation must contend with communities that are sensitive to the interacting effects of altered flood regimes and water availability from river and precipitation. å©2015. American Geophysical Union. All Rights Reserved

Inclusion of Experimental Information in First Principles Modeling of Materials

We propose a novel approach to model amorphous materials using a first principles density functional method while simultaneously enforcing agreement with selected experimental data. We illustrate our method with applications to amorphous silicon and glassy GeSe$_2$. The structural, vibrational and electronic properties of the models are found to be in agreement with experimental results. The method is general and can be extended to other complex materials.Comment: 11 pages, 8 PostScript figures, submitted to J. Phys.: Condens. Matter in honor of Mike Thorpe's 60th birthda

Atomic Forces from Electronic Energies Via the Hellmann-Feynman Theorem, with Application to Semiconductor (110) Surface Relaxation

Journals published by the American Physical Society can be found at http://journals.aps.org