53 research outputs found
Phased Array Ultrasound: Initial Development of PAUT Inspection of Self-Reacting Friction Stir Welds
This slide presentation reviews the development of Phased Array Ultrasound (PAUT) as a non-destructive examination method for Self Reacting Friction Stir Welds (SR-FSW). PAUT is the only NDE method which has been shown to detect detrimental levels of Residual Oxide Defect (ROD), which can result in significant decrease in weld strength. The presentation reviews the PAUT process, and shows the results in comparison with x-ray radiography
Finite size effects with variable range exchange coupling in thin-film Pd/Fe/Pd trilayers
The magnetic properties of thin-film Pd/Fe/Pd trilayers in which an embedded
~1.5 A-thick ultrathin layer of Fe induces ferromagnetism in the surrounding Pd
have been investigated. The thickness of the ferromagnetic trilayer is
controlled by varying the thickness of the top Pd layer over a range from 8 A
to 56 A. As the thickness of the top Pd layer decreases, or equivalently as the
embedded Fe layer moves closer to the top surface, the saturated magnetization
normalized to area and the Curie temperature decrease whereas the coercivity
increases. These thickness-dependent observations for proximity-polarized
thin-film Pd are qualitatively consistent with finite size effects that are
well known for regular thin-film ferromagnets. The critical exponent of
the order parameter (magnetization) is found to approach the mean field value
of 0.5 as the thickness of the top Pd layer increases. The functional forms for
the thickness dependences, which are strongly modified by the nonuniform
exchange interaction in the polarized Pd, provide important new insights to
understanding nanomagnetism in two-dimensions.Comment: 14 pages, 5 figures, submitted to JMM
Colossal magnetocapacitance and scale-invariant dielectric response in phase-separated manganites
Thin films of strongly-correlated electron materials (SCEM) are often grown
epitaxially on planar substrates and typically have anisotropic properties that
are usually not captured by edge-mounted four-terminal electrical measurements,
which are primarily sensitive to in-plane conduction paths. Accordingly, the
correlated interactions in the out-of-plane (perpendicular) direction cannot be
measured but only inferred. We address this shortcoming and show here an
experimental technique in which the SCEM under study, in our case a 600
Angstrom-thick (La1-yPry)0.67Ca0.33MnO3 (LPCMO) film, serves as the base
electrode in a metal-insulator-metal (MIM) trilayer capacitor structure. This
unconventional arrangement allows for simultaneous determination of colossal
magnetoresistance (CMR) associated with dc transport parallel to the film
substrate and colossal magnetocapacitance (CMC) associated with ac transport in
the perpendicular direction. We distinguish two distinct strain-related
direction-dependent insulator-metal (IM) transitions and use Cole-Cole plots to
establish a heretofore unobserved collapse of the dielectric response onto a
universal scale-invariant power-law dependence over a large range of frequency,
temperature and magnetic field.Comment: 32 pages, 4 figures, Supplementary section included, Submitted to
Nature Physic
Pulmonary hemodynamic responses to in utero ventilation in very immature fetal sheep
<p>Abstract</p> <p>Background</p> <p>The onset of ventilation at birth decreases pulmonary vascular resistance (PVR) resulting in a large increase in pulmonary blood flow (PBF). As the large cross sectional area of the pulmonary vascular bed develops late in gestation, we have investigated whether the ventilation-induced increase in PBF is reduced in immature lungs.</p> <p>Methods</p> <p>Surgery was performed in fetal sheep at 105 d GA (n = 7; term ~147 d) to insert an endotracheal tube, which was connected to a neonatal ventilation circuit, and a transonic flow probe was placed around the left pulmonary artery. At 110 d GA, fetuses (n = 7) were ventilated <it>in utero </it>(IUV) for 12 hrs while continuous measurements of PBF were made, fetuses were allowed to develop <it>in utero </it>for a further 7 days following ventilation.</p> <p>Results</p> <p>PBF changes were highly variable between animals, increasing from 12.2 ± 6.6 mL/min to a maximum of 78.1 ± 23.1 mL/min in four fetuses after 10 minutes of ventilation. In the remaining three fetuses, little change in PBF was measured in response to IUV. The increases in PBF measured in responding fetuses were not sustained throughout the ventilation period and by 2 hrs of IUV had returned to pre-IUV control values.</p> <p>Discussion and conclusion</p> <p>Ventilation of very immature fetal sheep <it>in utero </it>increased PBF in 57% of fetuses but this increase was not sustained for more than 2 hrs, despite continuing ventilation. Immature lungs can increase PBF during ventilation, however, the present studies show these changes are transient and highly variable.</p
Air Force commodity Councils: leveraging the power of procurement
Acquisition research (Graduate School of Business & Public Policy)The United States Air Force is always looking for ways to improve practices while leveraging the taxpayers? dollar. The Air Force currently spends about one-third of its annual budget on purchased goods and services. This offers the Air Force a large target in which to seek cost savings. Commercial firms have moved toward a commodity-council approach for purchasing in recent years, and the cost reductions realized have been impressive. Findings have shown that the increased leverage from commodity councils will optimize buying power for the Air Force, reduce duplication of effort, improve customer support, and minimize supply-chain costs through integration and collaboration. ?Commodity Council? is a term used to describe a cross-functional sourcing team designed to create a centralized purchasing strategy and establish centralized contracts for enterprise-wide requirements. The commodity council drives commonality and standardization and ensures the leveraging of purchasing volume. The key to this approach is to rely on market experts in the specific commodity category to make well informed, market-savvy decisions that fully meet all enterprise-wide requirements for a commodity. A ?commodity? is simply defined as a segmentable category of goods and/or services. Note, this definition does not imply an expendable or non-complex item (Hansen 1). In this research, I analyze the experiences of the newly-formed Air Force Information Technology Commodity Council (AFITCC) at Headquarters Standard Systems Group (HQ SSG or SSG), Maxwell Air Force Base (MAFB)?Gunter Annex, Alabama, for results and lessons learned.Approved for public release; distribution is unlimited
The impact of commodity councils on the internal structures of purchasing organizations in the United States Air Force
MBA Professional ReportTo better support the warfighter, the Department of Defense is emulating industry's Best Commercial Practices (BCP). Identified as a BCP, strategic sourcing is an integral part of the procurement transformation, aimed at buying products cheaper and faster. Success in the commercial industry has shown that strategic sourcing is a powerful tool that can significantly cut costs and improve customer responsiveness. The Air Force has taken initial steps to implement strategic sourcing into their purchasing organizations through commodity councils. This research uses the case study method to identify patterns and trends experienced by commercial companies in their implementation of strategic sourcing. In particular, it focuses on 1) job description 2) training 3) manpower 4) realignment 5) procedures and 6) human aspect. Further analysis compares these "lessons learned" to current Air Force practices and discusses potential barriers and to what extent they can be adopted. Based on these findings, specific recommendations are made to better help the Air Force enable this transformation.http://archive.org/details/theimpactofcommo109459912First Lieutenant, United States Air ForceApproved for public release; distribution is unlimited
Neuronal nitric oxide synthase does not contribute to the modulation of pulmonary vascular tone in fetal lambs with congenital diaphragmatic hernia (nNOS in CDH lambs).
AIM: The aim of this study was to determine the presence of the neuronal nitric oxide synthase (nNOS) in near full-term lambs with congenital diaphragmatic hernia (CDH) and its role in the modulation of pulmonary vascular basal tone. METHODS: We surgically created diaphragmatic hernia on the 85th day of gestation. On the 135th, catheters were used to measure pulmonary pressure and blood flow. We tested the effects of 7-nitroindazole (7-NINA), a specific nNOS antagonist and of N-nitro-L-arginine (L-NNA), a nonspecific nitric oxide synthase antagonist. In vitro, we tested the effects of the same drugs on isolated pulmonary vessels. The presence of nNOS protein in the lungs was detected by Western blot analysis. RESULTS: Neither 7-NINA nor L-NNA modified pulmonary vascular basal tone in vivo. After L-NNA injection, acetylcholine (ACh) did not decrease significantly pulmonary vascular resistance (PVR). In vitro, L-NNA increased the cholinergic contractile-response elicited by electric field stimulation (EFS) of vascular rings from lambs with diaphragmatic hernia. CONCLUSION: We conclude that nNOS protein is present in the lungs and pulmonary artery of near full-term lamb fetuses with diaphragmatic hernia, but that it does not contribute to the reduction of pulmonary vascular tone at birt
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