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Brown A.,Dynamic Certification Laboratories | Saiidi M.S.,Mail Stop
Earthquake Engineering and Engineering Vibration

The objective of this study was to investigate the effects of near-fault ground motions on substandard bridge columns and piers. To accomplish these goals, several large scale reinforced concrete models were constructed and tested on a shake table using near- and far-field ground motion records. Because the input earthquakes for the test models had different characteristics, three different measures were used to evaluate the effect of the input earthquake. These measures are peak shake table acceleration, spectral acceleration at the fundamental period of the test specimens, and the specimen drift ratios. For each measure, force-displacement relationships, strains, curvatures, drift ratios, and visual damage were evaluated. Results showed that regardless of the measure of input or response, the near-fault record generally led to larger strains, curvatures, and drift ratios. Furthermore, residual displacements were small compared to those for columns meeting current seismic code requirements. © 2011 Institute of Engineering Mechanics, China Earthquake Administration and Springer Berlin Heidelberg. Source

Cozmuta I.,Eloret Corporation | Mansour N.N.,Mail Stop
Journal of Spacecraft and Rockets

Amultiscale approach is used to model and analyze the ablation of porous materials. Models are developed for the oxidation of a carbon preform and of the char layer of two phenolic impregnated carbon ablators with the same chemical composition but with different structures. Oxygen diffusion through the pores of the materials and in depth oxidation and mass loss are first modeled at the microscopic scale. The microscopic model is then averaged to yield a set of partial differential equations describing the macroscopic behavior of the material. Microscopic and macroscopic approaches are applied with progressive degrees of complexity to gain a comprehensive understanding of the ablation process. Porous medium ablation is found to occur in a zone of the char layer that we call the ablation zone. The thickness of the ablation zone is a decreasing function of the Thiele number. The studied materials are shown to display different ablation behaviors, a fact not captured by current models that are based on chemical composition only. Applied to Stardust's phenolic impregnated carbon ablator, the models explain and reproduce the unexpecteddrop in density measured in the char layer during Stardust postflight analyses [Stackpoole, M., Sepka, S., Cozmuta, I., and Kontinos, D., "Post-Flight Evaluation of StardustSample Return Capsule Forebody Heat-Shield Material," AIAA Paper 2008-1202, Jan. 2008]. © Clearance Center, Inc. Source

Wercinski P.F.,Mail Stop | Jenniskens P.,Carl Sagan Center
Journal of Spacecraft and Rockets

The 15 January 2006 reentry of the Stardust Sample Return capsule was photographed from 11.2-km altitude onboard NASA's DC-8 Airborne Laboratory in a series of brief 1/320 s exposures with a Nikon D70 digital still camera. The entry was detected from 09:57:13.5 to 09:57:53.5 UTC. Other instruments have demonstrated that most of the observed broadband flux is due to gray body radiation from the hot surface of the thermal protection system, except in the very beginning when strong emission lines of zinc from an ablating paint layer contributed significantly to the blue band. The measured flux in the green band was used to measure the surface-averaged temperature variation during flight, and the corresponding flux in the blue and red bands were used to verify the expected wavelength dependence of the gray body emission. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. Source

Pinto M.P.,Mail Stop | Pinto M.P.,Andres Bello University | Dye W.W.,Mail Stop | Jacobsen B.M.,Aurora University | And 2 more authors.
BMC Cancer

Background: Luminal, estrogen receptor-positive breast cancers represent more than 70% of cases. Despite initial good prognoses one third of Luminal cancers eventually recur locally or at distant sites and exhibit hormone resistance. Here we demonstrate that factors elaborated by malignant stromal cells can induce Luminal tumor cells proliferation and promote angiogenesis and hormone independence. We recently isolated a malignant mouse mammary gland stromal cell line named BJ3Z that increases proliferation and angiogenesis in estrogen-free xenografted Luminal MCF-7 breast cancer cells.Methods: BJ3Z and Normal mouse mammary Fibroblasts (NMFs) were expression profiled using microarray assays. Messenger RNA levels were confirmed by RT-PCR and by immunohistochemistry (IHC). Breast cancer MCF-7, BT-474, BT-20 and MDA-MB-231cell lines and stromal BJ3Z and NMFs were grown for in vitro assays: breast cancer cell lines were treated with stromal cells conditioned media, for three-dimensional (3D) mono and co-cultures in Matrigel, proliferation was measured by Bromo-deoxyuridine (BrdU) incorporation using IHC. Tubule formation in vitro, a proxy for angiogenesis, was assessed using 3D cultured Human Umbilical cord Vascular Endothelial Cells (HUVEC).Results: We show that under estrogen-free conditions, BJ3Z cells but not NMFs increase proliferation of co-cultured Luminal but not basal-like human breast cancer cells in 2D or as 3D Matrigel colonies. Gene expression profiling, RT-PCR analysis and IHC of colony-derived BJ3Z cells and NMFs shows that Platelet Derived Growth Factor ligands (PDGF-A and -B) are elaborated by BJ3Z cells but not NMFs; while PDGF receptors are present on NMFs but not BJ3Z cells. As a result, in colony co-culture assays, BJ3Z cells but not NMFs increase MCF-7 cell proliferation. This can be mimicked by direct addition of PDGF-BB, and blocked by the PDGF receptor inhibitor Imatinib Mesylate. Both normal and malignant stromal cells enhance angiogenesis in an in vitro model. This effect is also due to PDGF and is suppressed by Imatinib.Conclusions: We provide evidence that Luminal breast cancer cells can be targeted by the PDGF signaling pathway leading to estrogen-independent proliferation and angiogenesis. We speculate that stroma-directed therapies, including anti-PDGFR agents like Imatinib, may be useful in combination with other therapies for treatment of luminal cancers. © 2014 Pinto et al.; licensee BioMed Central Ltd. Source

Nugent-Glandorf L.,Mail Stop | Johnson T.A.,Mail Stop | Kobayashi Y.,University of Tokyo | Diddams S.A.,Mail Stop
Optics InfoBase Conference Papers

We measure amplitude and frequency noise of a Yb fiber laser frequency comb in different dispersion regimes. Low cavity dispersion yields the lowest noise frequency comb. © OSA/CLEO 2011. Source

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