41 research outputs found

    Constraining a Historical Black Carbon Emission Inventory of the United States for 1960–2000

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    We present an observationally constrained United States black carbon emission inventory with explicit representation of activity and technology between 1960 and 2000. We compare measured coefficient of haze data in California and New Jersey between 1965 and 2000 with predicted concentration trends and attribute discrepancies between observations and predicted concentrations among several sources based on seasonal and weekly patterns in observations. Emission factors for sources with distinct fuel trends are then estimated by comparing fuel and concentration trends and further substantiated by in‐depth examination of emission measurements. We recommend (1) increasing emission factors for preregulation vehicles by 80–250%; (2) increasing emission factors for residential heating stoves and boilers by 70% to 200% for 1980s and before; (3) explicitly representing naturally aspired off‐road engines for 1980s and before; and (4) explicitly representing certified wood stoves after 1985. We also evaluate other possible sources for discrepancy between model and measurement, including bias in modeled meteorology, subgrid spatial heterogeneity of concentrations, and inconsistencies in reported fuel consumption. The updated U.S. emissions are higher than the a priori estimate by 80% between 1960 and 1980, totaling 690 Gg/year in 1960 and 620 Gg/year in 1970 (excluding open burning). The revised inventory shows a strongly decreasing trend that was present in the observations but missing in the a priori inventory.Key PointsSystematic evaluation of long‐term U.S. black carbon observations identifies a small number of poorly estimated emission sourcesUpdated black carbon emission is higher than the previous estimate by 80% for 1960–1980, showing a decreasing trend as found in observationEmission factors for preregulation vehicles, off‐road engines, and residential heating stoves in 1980 and before should be increasedPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149266/1/jgrd55339_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149266/2/jgrd55339.pd

    Chemotactic response and adaptation dynamics in Escherichia coli

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    Adaptation of the chemotaxis sensory pathway of the bacterium Escherichia coli is integral for detecting chemicals over a wide range of background concentrations, ultimately allowing cells to swim towards sources of attractant and away from repellents. Its biochemical mechanism based on methylation and demethylation of chemoreceptors has long been known. Despite the importance of adaptation for cell memory and behavior, the dynamics of adaptation are difficult to reconcile with current models of precise adaptation. Here, we follow time courses of signaling in response to concentration step changes of attractant using in vivo fluorescence resonance energy transfer measurements. Specifically, we use a condensed representation of adaptation time courses for efficient evaluation of different adaptation models. To quantitatively explain the data, we finally develop a dynamic model for signaling and adaptation based on the attractant flow in the experiment, signaling by cooperative receptor complexes, and multiple layers of feedback regulation for adaptation. We experimentally confirm the predicted effects of changing the enzyme-expression level and bypassing the negative feedback for demethylation. Our data analysis suggests significant imprecision in adaptation for large additions. Furthermore, our model predicts highly regulated, ultrafast adaptation in response to removal of attractant, which may be useful for fast reorientation of the cell and noise reduction in adaptation.Comment: accepted for publication in PLoS Computational Biology; manuscript (19 pages, 5 figures) and supplementary information; added additional clarification on alternative adaptation models in supplementary informatio

    The Blue Studio: designing an interactive environment for embodied multi-stakeholder ideation processes

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    This paper describes the process of designing the Blue Studio: An interactive space for embodied multi-stakeholder ideation processes. Inspired by embodied sensemaking - the way people make sense of things through external expression and interaction with other people - we iteratively designed material, interactive and spatial interventions in the Blue Studio and evaluated them with multi-stakeholder participants in various studies. Thereupon, we analyzed the impact of the design interventions, based on the seven principles to design for embodied sensemaking and highlighted opportunities for refining our interactive space for embodied ideation. Based on the insights gained, a final design of the Blue Studio was realized and evaluated on functionality

    A comparative study of shear stresses in collagen-glycosaminoglycan and calcium phosphate scaffolds in bone tissue-engineering bioreactors

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    The increasing demand for bone grafts, combined with their limited availability and potential risks, has led to much new research in bone tissue engineering. Current strategies of bone tissue engineering commonly use cell-seeded scaffolds and flow perfusion bioreactors to stimulate the cells to produce bone tissue suitable for implantation into the patient\u27s body. The aim of this study was to quantify and compare the wall shear stresses in two bone tissue engineering scaffold types (collagen-glycosaminoglycan (CG) and calcium phosphate) exposed to fluid flow in a perfusion bioreactor. Based on micro-computed tomography images, three-dimensional numerical computational fluid dynamics (CFD) models of the two scaffold types were developed to calculate the wall shear stresses within the scaffolds. For a given flow rate (normalized according to the cross-sectional area of the scaffolds), shear stress was 2.8 times as high in the CG as in the calcium-phosphate scaffold. This is due to the differences in scaffold geometry, particularly the pore size (CG pore size ∌96ÎŒm, calcium phosphate pore size ∌350ÎŒm). The numerically obtained results were compared with those from an analytical method that researchers use widely experimentalists to determine perfusion flow rates in bioreactors. Our CFD simulations revealed that the cells in both scaffold types were exposed to a wide range of wall shear stresses throughout the scaffolds and that the analytical method predicted shear stresses 12% to 21% greater than those predicted using the CFD method. This study demonstrated that the wall shear stresses in calcium phosphate scaffolds (745.2 mPa) are approximately 40 times as high as in CG scaffolds (19.4 mPa) when flow rates are applied that have been experimentally used to stimulate the release of prostaglandin E2. These findings indicate the importance of using accurate computational models to estimate shear stress and determine experimental conditions in perfusion bioreactors for tissue engineering. © 2009, Mary Ann Liebert, Inc

    The Blue Studio:designing an interactive environment for embodied multi-stakeholder ideation processes

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    \u3cp\u3eThis paper describes the process of designing the Blue Studio: An interactive space for embodied multi-stakeholder ideation processes. Inspired by embodied sensemaking - the way people make sense of things through external expression and interaction with other people - we iteratively designed material, interactive and spatial interventions in the Blue Studio and evaluated them with multi-stakeholder participants in various studies. Thereupon, we analyzed the impact of the design interventions, based on the seven principles to design for embodied sensemaking and highlighted opportunities for refining our interactive space for embodied ideation. Based on the insights gained, a final design of the Blue Studio was realized and evaluated on functionality.\u3c/p\u3

    Seven principles to design for embodied sensemaking

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    The TEI-community is based a various paradigms. We believe that the community matures by scrutinising these different paradigms and unravelling the consequences for designing for tangible, embedded and embodied interaction. In this paper we explore the consequences and possibilities of phenomenology-inspired embodied theory, and more specifically the concept of embodied sensemaking, i.e. human sensemaking using sensorimotor couplings to support social coordination between people. Based on our theoretical setting, we introduce seven design principles for developing face-to-face embodied sensemaking technology. We show in this paper how we used these principles to develop a mobile design and sensemaking studio for the encounter between two persons to sketch a future at the cross-section of their disciplines. By explaining these principles, we aim to show what embodied theory can bring the TEI-community, and invite others to do the same

    The Power of Provisional/Immediate Language Revisited: Adding Student Personality Traits to the Mix

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    Previous research found that relatively minor changes in the wording of written assessments can influence students\u27 motivation and affect toward the teacher. Not considered previously, however, is the role that student personality traits might play. Are the observed effects consistent across various personality types, or are different personality types affected differently by the same teacher behaviors? This study takes a first step toward answering that question, replicating the previous written feedback style research while adding the dimension of student personality traits to the investigation. The results suggest that the treatment may not be effective for those with high extroversion, low conscientiousness, and low neuroticism. When those cases were excluded from the analysis, the variance accounted for increased substantially, supporting the notion that efficacy of the teacher behaviors is, in part, dependent on student personality traits. © 2013 Copyright Eastern Communication Association

    Balance of Mass, Momentum, and Energy in Splintering Central Collisions for 40Ar up to 115 MeV/Nucleon

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    For central collisions of (17–115)AMeV 40Ar+Cu, Ag, Au, an overall balance is determined for the average mass, energy, and longitudinal momentum. Light charged particles and fragments are separated into forward-focused and isotropic components in the frame of the heaviest fragment. Energy removal by the isotropic component reaches 1–2 GeV. For such high deposition energies, statistical multifragmentation models predict much more extensive nuclear disassembly than is observed
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