762 research outputs found

    Current State of Strain in the Central Cascadia Margin Derived from Changes in Distance between GPS Stations

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    Using continuously operating Global Positioning Stations in the Pacific Northwest of the United States, over 100 station-station baseline length changes were determined along seven West-East transects, two North-South transects and in three localized areas to determine both the average annual strains over the past several years, and the variation in strain over the central Cascadia convergent margin. The North-South transects (composed of multiple baselines) show shortening. Along West-East transects some baselines show shortening and others extension. The direction of the principle strains calculated for two areas 100 km from the deformation front are close to per-pendicular to the deformation front. The North-South strains are 10?8 a?1, which is an order-of-magnitude less than the West-East strains (10?7 a?1). Along several West-East transects, the magnitude of the strain increases away from the deformation front. All West-East transects showed a change in strain 250 km inland from deformation front

    Lightning Observations and Tropical Cyclogenesis in the Atlantic and East Pacific

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    It has been hypothesized that deep, intense convective-scale "hot" towers may aid the process of tropical cyclogenesis and intensification through dynamic and thermodynamic feedbacks on the larger meso-to-synoptic scale circulation. In this study, we make use of NCEP Reanalysis data and Tropical Rainfall Measurement Mission (TRMM) lightning imaging sensor (LIS), precipitation radar (PR), and microwave imager (TMI) data to investigate the role that widespread and/or intense lightning-producing convection (i.e., "electrically-hot towers") present in African easterly waves (AEWs) may play in tropical cyclogenesis over the Atlantic, Caribbean, and East Pacific regions. NCEP Reanalysis 700 hPa meridional winds for the months of June to November for the years 2001-2009 were analyzed for the domain of 5degN-20degN and 130degW-20degE in order to partition individual AEWs into northerly, southerly, trough, and ridge phases. Subsequently, information from National Hurricane Center (NHC) storm reports was used to divide the waves into developing and non-developing waves. In addition, information from the NHC reports was used to further divide the developing waves into those waves that spawned storms that only developed to tropical storm strength and those that spawned storms that reached hurricane strength. The developing waves were also divided by the region in which they developed. To assess the evolution of convection associated with the AEWs as they propagated across our analysis domain, the full 130degW-20degE domain was divided into five longitude bands, and waves were analyzed for each band. To help determine the gross nature of the smaller convective scale, composites were created of all developing and non-developing waves as a function of AEW wave phase over the full analysis domain and each longitude band by compositing TRMM PR, TMI, LIS, and IR brightness temperature data extracted from the NASA global-merged infrared brightness temperature dataset. Finally, similar composites were created using various NCEP variables to assess the nature of the larger scale environment and circulation

    Using Modeling and Simulation to Examine the Benefits of a Network Tasking Order

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    The Global Information Grid (GIG) is the military’s computer and communications network which supports the myriad of military missions. Military missions are highly planned, passing through many hands in the strategy-to-task methodology to ensure completeness, accuracy, coordination, cohesion, and appropriateness. A benefit of this planning is the possibility to collect knowledge of future conditions that could be of use to network designers whose goals include optimizing and protecting the GIG. This advanced knowledge includes which networked military equipment will be involved, what their capabilities are, where they will be, when they will be there, and particulars on the required data flows. A Network Tasking Order process is proposed as a means of collecting this information, analyzing the information to generate network taskings, and disseminating those taskings. Tactical integration of assets in mobile networks is introduced as another planning variable in the battlefield; not unlike logistical considerations such as fuel, ammunition, water, and so on used currently in operation planning. Modeling and simulation is used to support the proposed benefits

    Application of Dynamic System Identification to Timber Beams - part I

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    In this first part of a two-part paper, development of a method of dynamic system identification for timber beams is presented with an analytical verification of the method using a finite-element model. A method of global nondestructive evaluation for identifying local damage and decay in timber beams is investigated in this paper. Experimental modal analysis is used in conjunction with a previously developed damage localization algorithm. The damage localization algorithm utilizes changes in modal strain energy between the mode shapes of a calibrated model, representing the undamaged state of the beam of interest, and the experimentally obtained mode shapes for a timber beam. Analytical evaluations were performed to demonstrate and verify the use of this method of global nondestructive evaluation for the localization of damage or decay in timber beams. In a companion paper, experimental laboratory tests are presented that verify the use of dynamic system identification to locate damage within timber beams

    A mechanism for assembly of complexes of vitronectin and plasminogen activator inhibitor-1 from sedimentation velocity analysis

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    Plasminogen activator inhibitor-1 (PAI-1) and vitronectin are cofactors involved in pathological conditions such as injury, inflammation, and cancer, during which local levels of PAI-1 are increased and the active serpin forms complexes with vitronectin. These complexes become deposited into surrounding tissue matrices, where they regulate cell adhesion and pericellular proteolysis. The mechanism for their co-localization has not been elucidated. We hypothesize that PAI-1-vitronectin complexes form in a stepwise and concentration-dependent fashion via 1:1 and 2:1 intermediates, with the 2:1 complex serving a key role in assembly of higher order complexes. To test this hypothesis, sedimentation velocity experiments in the analytical ultracentrifuge were performed to identify different PAI-1-vitronectin complexes. Analysis of sedimentation data invoked a novel multisignal method to discern the stoichiometry of the two proteins in the higher-order complexes formed (Balbo, A., Minor, K. H., Velikovsky, C. A., Mariuzza, R. A., Peterson, C. B., and Schuck, P. (2005) Proc. Natl. Acad. Sci. U. S. A. 102, 81-86). Our results demonstrate that PAI-1 and vitronectin assemble into higher order forms via a pathway that is triggered upon saturation of the two PAI-1-binding sites of vitronectin to form the 2:1 complex. This 2:1 PAI-1-vitronectin complex, with a sedimentation coefficient of 6.5 S, is the key intermediate for the assembly of higher order complexes

    \u3cem\u3ecatena\u3c/em\u3e-Poly[[diaquadinitratozinc(II)]bis(ÎĽ-1,4-di-3-pyridyl-2,3-diaza-1,3-butadiene)]

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    The polymeric title complex, [Zn(NO3)2(C24H20N8)(H2O)2]n, features distorted ZnN2O4 octahedra with each ZnII atom being located on an inversion center. Adjacent Zn ions are doubly bridged by two equivalent 1,4-di-3-pyridyl-2,3-diaza-1,3-butadiene ligands to form linear chains

    Convergence of Agriculture and Energy: II. Producing Cellulosic Biomass for Biofuels

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    Global energy demand is increasing as known global petroleum supplies are decreas¬ing. Calls to supplement or replace the current fossil-based energy system with new, envi¬ronmentally and economically sustainable strategies continue to increase, especially in light of more expensive traditional energy sources. Various governmental agencies and working groups have set aggressive targets and timelines for decreasing fossil fuel consumption by substituting bio-based energy (Bush 2007; Foust et al. 2007; Perlack et al. 2005; Smith et al. 2004). The alignment and continuity of these goals is illustrated in Figure 1. Current biofuel production in the United States relies primarily on corn grain conver¬sion to ethanol, but future systems are expected to depend more intensively on plant biomass than on grain as a feedstock for production of ethanol and other biofuels. In addition, current cropping systems generally are designed to optimize grain production and are not designed to harvest all the aboveground portion of the plant for cellulose-containing biomass. Significant, immediate national investments are needed, along with changes in policy, to address chal¬lenges limiting the sustainable production and efficient use of cellulosic biomass as a fuel feedstock to meet anticipated U.S. demand. The Bush Administration outlined a portfolio of recommended technologies, pro¬cesses, and practices for bio-based energy production that targets improved rates of feedstock conversion and greater efficiency in energy use. The plan also states that a significant portion of the nation’s 2017 energy supply, especially transportation fuel, will come from conversion of biomass feedstock to liquid fuels. Considering just the biomass-derived fuels contribution, roughly 250 million tons or more of grain and cellulosic biomass per year will be needed to reach the 10-year goal, and 650 to 700 million tons per year of biomass to reach the 2025 goal (Figure 1)

    Structure–activity relationship study of bone morphogenetic protein (BMP) signaling inhibitors

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    A structure–activity relationship study of dorsomorphin, a previously identified inhibitor of SMAD 1/5/8 phosphorylation by bone morphogenetic protein (BMP) type 1 receptors ALK2, 3, and 6, revealed that increased inhibitory activity could be accomplished by replacing the pendent 4-pyridine ring with 4-quinoline. The activity contributions of various nitrogen atoms in the core pyrazolo[1,5-a]pyrimidine ring were also examined by preparing and evaluating pyrrolo[1,2-a]pyrimidine and pyrazolo[1,5-a]pyridine derivatives. In addition, increased mouse liver microsome stability was achieved by replacing the ether substituent on the pendent phenyl ring with piperazine. Finally, an optimized compound 13 (LDN-193189 or DM-3189) demonstrated moderate pharmacokinetic characteristics (e.g., plasma t1/2 = 1.6 h) following intraperitoneal administration in mice. These studies provide useful molecular probes for examining the in vivo pharmacology of BMP signaling inhibition
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