1,540 research outputs found

    Microwave Electronics

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    Contains reports on four research projects.Lincoln Laboratory (Purchase Order B-00306)United States Air Force (Contract AF19(604)-5200)United States NavyUnited States Arm

    In vivo microCT-based time-lapse morphometry reveals anatomical site-specific differences in bone (re)modeling serving as baseline parameters to detect early pathological events

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    The bone structure is very dynamic and continuously adapts its geometry to external stimuli by modeling and remodeling the mineralized tissue. In vivo microCT-based time-lapse morphometry is a powerful tool to study the temporal and spatial dynamics of bone (re)modeling. Here an advancement in the methodology to detect and quantify site-specific differences in bone (re)modeling of 12-week-old BALB/c nude mice is presented. We describe our method of quantifying new bone surface interface readouts and how these are influenced by bone curvature. This method is then used to compare bone surface (re)modeling in mice across different anatomical regions to demonstrate variations in the rate of change and spatial gradients thereof. Significant differences in bone (re)modeling baseline parameters between the metaphyseal and epiphyseal are shown, as well as cortical and trabecular bone of the distal femur and proximal tibia. These results are validated using conventional static in vivo microCT analysis. Finally, the insights from these new baseline values of physiological bone (re)modeling were used to evaluate pathological bone (re)modeling in a pilot breast cancer bone metastasis model. The method shows the potential to be suitable to detect early pathological events and track their spatio-temporal development in both cortical and trabecular bone. This advancement in (re)modeling surface analysis and defined baseline parameters according to distinct anatomical regions will be valuable to others investigating various disease models with site-distinct local alterations in bone (re)modeling.ER

    A Joint Soil-Vegetation-Atmospheric Modeling Procedure of Water Isotopologues: Implementation and Application to Different Climate Zones With WRF-Hydro-Iso

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    Water isotopologues, as natural tracers of the hydrological cycle on Earth, provide a unique way to assess the skill of climate models in representing realistic atmospheric-terrestrial water pathways. This study presents the newly developed WRF-Hydro-iso, which is a version of the coupled atmospheric-hydrological WRF-Hydro model enhanced with a joint soil-vegetation-atmospheric description of water isotopologue motions. It allows the consideration of isotopic fractionation processes during water phase changes in the atmosphere, the land surface, and the subsurface. For validation, WRF-Hydro-iso is applied to two different climate zones, namely Europe and Southern Africa under the present climate conditions. Each case is modeled with a domain employing a 5 km grid-spacing coupled with a terrestrial subgrid employing a 500 m grid-spacing in order to represent lateral terrestrial water flow. A 10-year slice is simulated for 2003–2012, using ERA5 reanalyses as driving data. The boundary condition of isotopic variables is prescribed with mean values from a 10-year simulation with the Community Earth System Model Version 1. WRF-Hydro-iso realistically reproduces the climatological variations of the isotopic concentrations σP_{P}18^{18}O and σP_{P}2^{2}H from the Global Network of Isotopes in Precipitation. In a sensitivity analysis, it is found that land surface evaporation fractionation increases the isotopic concentrations in the rootzone soil moisture and slightly decreases the isotopic concentrations in precipitation. Lateral terrestrial water flow minorly affects these isotopic concentrations through changes in evaporation-transpiration partitioning

    Tautness for riemannian foliations on non-compact manifolds

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    For a riemannian foliation F\mathcal{F} on a closed manifold MM, it is known that F\mathcal{F} is taut (i.e. the leaves are minimal submanifolds) if and only if the (tautness) class defined by the mean curvature form κμ\kappa_\mu (relatively to a suitable riemannian metric μ\mu) is zero. In the transversally orientable case, tautness is equivalent to the non-vanishing of the top basic cohomology group Hn(M/F)H^{^{n}}(M/\mathcal{F}), where n = \codim \mathcal{F}. By the Poincar\'e Duality, this last condition is equivalent to the non-vanishing of the basic twisted cohomology group Hκμ0(M/F)H^{^{0}}_{_{\kappa_\mu}}(M/\mathcal{F}), when MM is oriented. When MM is not compact, the tautness class is not even defined in general. In this work, we recover the previous study and results for a particular case of riemannian foliations on non compact manifolds: the regular part of a singular riemannian foliation on a compact manifold (CERF).Comment: 18 page

    Cohomological tautness for Riemannian foliations

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    In this paper we present some new results on the tautness of Riemannian foliations in their historical context. The first part of the paper gives a short history of the problem. For a closed manifold, the tautness of a Riemannian foliation can be characterized cohomologically. We extend this cohomological characterization to a class of foliations which includes the foliated strata of any singular Riemannian foliation of a closed manifold

    Modified differentials and basic cohomology for Riemannian foliations

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    We define a new version of the exterior derivative on the basic forms of a Riemannian foliation to obtain a new form of basic cohomology that satisfies Poincar\'e duality in the transversally orientable case. We use this twisted basic cohomology to show relationships between curvature, tautness, and vanishing of the basic Euler characteristic and basic signature.Comment: 20 pages, references added, minor corrections mad

    A Model of Continuous Improvement Programme Management

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    The aim of this study is to identify key management decisions that enable the sustainment of a continuous improvement (CI) initiative. To accomplish this aim, we examine the procedures and practices used by two manufacturing companies for the management of their CI initiatives; one that is successfully sustaining the effectiveness of its CI initiative and another failing to do the same. This research makes two contributions to the conceptual understanding of CI programme management. First, we identify five CI programme management factors that enable the sustainment of a CI initiative. Second, the five factors are incorporated into a new CI programme management model. The model details a ‘bottom-up’ procedure for the generation of manufacturing performance improvement ideas and the management of their implementation

    Improved S factor of the 12C(p,γ)13N reaction at E=320–620 keV and the 422 keV resonance

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    The 12C(p,γ)13N reaction is the onset process of both the CNO and hot CNO cycles that drive massive star, red and asymptotic giant branch star, and novae nucleosynthesis. The 12C(p,γ)13N rate affects the final abundances of the stable 12,13C nuclides with ramifications for meteoritic carbon isotopic abundances and the s-process neutron source strength. Here, an underground measurement of the 12C(p,γ)13N cross section is reported. The present data, obtained at the Felsenkeller shallow-underground laboratory in Dresden (Germany), encompass the 320–620 keV center of mass energy range to include the wide and poorly constrained E=422 keV resonance that dominates the rate at high temperatures. This work's S-factor results, lower than literature by 25%, are included in a comprehensive R-matrix fit, and the energy of the 12+ first excited state of 13N is found to be 2369.6(4) keV with a radiative and proton width of 0.49(3) eV and 34.9(2) keV, respectively. A reaction rate, based on the present R-matrix fit and extrapolation, is suggested

    Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip

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    The ATLAS Collaboration will upgrade its semiconductor pixel tracking detector with a new Insertable B-layer (IBL) between the existing pixel detector and the vacuum pipe of the Large Hadron Collider. The extreme operating conditions at this location have necessitated the development of new radiation hard pixel sensor technologies and a new front-end readout chip, called the FE-I4. Planar pixel sensors and 3D pixel sensors have been investigated to equip this new pixel layer, and prototype modules using the FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test results are presented, including charge collection efficiency, tracking efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS
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