333 research outputs found

    Preparing for Climatic Change: The Water, Salmon, and Forests of the Pacific Northwest

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    The impacts of year-to-year and decade-to-decade climatic variations on some of the Pacific Northwest’s key natural resources can be quantified to estimate sensitivity to regional climatic changes expected as part of anthropogenic global climatic change. Warmer, drier years, often associated with El Niño events and/or the warm phase of the Pacific Decadal Oscillation, tend to be associated with below-average snowpack, streamflow, and flood risk, below-average salmon survival, below-average forest growth, and above-average risk of forest fire. During the 20th century, the region experienced a warming of 0.8 ◦C. Using output from eight climate models, we project a further warming of 0.5–2.5 ◦C (central estimate 1.5 ◦C) by the 2020s, 1.5–3.2 ◦C (2.3◦C) by the 2040s, and an increase in precipitation except in summer. The foremost impact of a warming climate will be the reduction of regional snowpack, which presently supplies water for ecosystems and human uses during the dry summers. Our understanding of past climate also illustrates the responses of human management systems to climatic stresses, and suggests that a warming of the rate projected would pose significant challenges to the management of natural resources. Resource managers and planners currently have few plans for adapting to or mitigating the ecological and economic effects of climatic change

    Preparing for Climatic Change: The Water, Salmon, and Forests of the Pacific Northwest

    Get PDF
    The impacts of year-to-year and decade-to-decade climatic variations on some of the Pacific Northwest’s key natural resources can be quantified to estimate sensitivity to regional climatic changes expected as part of anthropogenic global climatic change. Warmer, drier years, often associated with El Niño events and/or the warm phase of the Pacific Decadal Oscillation, tend to be associated with below-average snowpack, streamflow, and flood risk, below-average salmon survival, below-average forest growth, and above-average risk of forest fire. During the 20th century, the region experienced a warming of 0.8 ◦C. Using output from eight climate models, we project a further warming of 0.5–2.5 ◦C (central estimate 1.5 ◦C) by the 2020s, 1.5–3.2 ◦C (2.3◦C) by the 2040s, and an increase in precipitation except in summer. The foremost impact of a warming climate will be the reduction of regional snowpack, which presently supplies water for ecosystems and human uses during the dry summers. Our understanding of past climate also illustrates the responses of human management systems to climatic stresses, and suggests that a warming of the rate projected would pose significant challenges to the management of natural resources. Resource managers and planners currently have few plans for adapting to or mitigating the ecological and economic effects of climatic change

    Flipping Engineering Courses: A School Wide Initiative

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    In the 2013-2014 school year, we implemented the "flipped classroom" as part of an initiative to drive active learning, student engagement and enhanced learning in our school. The flipped courses consisted of freshman through senior engineering classes in introductory programming, statics/mechanics, mechanical design, bio-thermodynamics, facilities layout/material handling, and chemical engineering dynamics and modeling. In the flipped classroom, students watch video lectures beforehand to obtain the foundational knowledge and then demonstrate skills during class. Our study set out to address the following research questions: (1) Does the flipped classroom promote student engagement during class, and does it positively impact the classroom environment? (2) Is the flipped classroom associated with increased student achievement and learning of content? and (3) What strengths, benefits, and drawbacks do students perceive with the flipped classroom? To address these, we used a mixed methods approach, including environment and evaluation surveys, instructor interviews, exam and homework results, video access data, and structured classroom observation. Based on our use of the College and University Classroom Environment Inventory (CUCEI), we found evidence that flipped instruction can positively impact the classroom environment. We also used a behavioral observation protocol--the Teaching Dimensions Observation Protocol (TDOP)--to assess student engagement and involvement during class. We compared our results to a national TDOP study of 58 lecture-based STEM classrooms, formally demonstrating the advantages of our flipped classrooms. Behaviors such as student discussion and questions and problem solving were significantly higher in our flipped classrooms (p< 0.0001). Our pre-flip versus flip exam and homework results were mixed from a statistical improvement standpoint. However, based on instructor interviews we noted enhanced higher-order skills such as problem solving and deeper engagement and proficiency in some courses and with some students. Unfortunately, we encountered challenges with our freshman and seniors. The great majority of freshmen did not use the videos for first-time instruction. The seniors expressed resistance to and dissatisfaction with this instructional change. Both freshmen and seniors rated their classroom environments statistically lower than the sophomores and juniors did. We uncovered other instances in the literature of these challenges. Nonetheless, we believe that flipped instruction is a valuable approach for promoting engagement and learning. We discuss lessons learned, including the need to educate students about the expectations of the flipped classroom

    The role of dipole-forbidden autoionizing resonances in non-resonant one-color two-photon single ionization of N2_2

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    We present an experimental and theoretical energy- and angle-resolved study on the photoionization dynamics of non-resonant one-color two-photon single valence ionization of neutral N2_2 molecules. Using 9.3 eV photons produced via high harmonic generation and a 3-D momentum imaging spectrometer, we detect the photoelectrons and ions produced from one-color two-photon ionization in coincidence. Photoionization of N2_2 populates the X 2Σg+^2\Sigma^+_g, A 2Πu^2\Pi_u, and B 2Σu+^2\Sigma^+_u ionic states of N2+_2^+, where the photoelectron angular distributions associated with the X 2Σg+^2\Sigma^+_g and A 2Πu^2\Pi_u states both vary with changes in photoelectron kinetic energy of only a few hundred meV. We attribute the rapid evolution in the photoelectron angular distributions to the excitation and decay of dipole-forbidden autoionizing resonances that belong to series of different symmetries, all of which are members of the Hopfield series, and compete with the direct two-photon single ionization.Comment: 12 pages, 9 figures, 2 table

    The Specificity of Peptides Bound to Human Histocompatibility Leukocyte Antigen (HLA)-B27 Influences the Prevalence of Arthritis in HLA-B27 Transgenic Rats

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    Human histocompatibility leukocyte antigen B27 is highly associated with the rheumatic diseases termed spondyloarthropathies, but the mechanism is not known. B27 transgenic rats develop a spontaneous disease resembling the human spondyloarthropathies that includes arthritis and colitis. To investigate whether this disease requires the binding of specific peptides to B27, we made a minigene construct in which a peptide from influenza nucleoprotein, NP383-391 (SRYWAIRTR), which binds B27 with high affinity, is targeted directly to the ER by the signal peptide of the adenovirus E3/gp19 protein. Rats transgenic for this minigene, NP1, were made and bred with B27 rats. The production of the NP383-391 peptide in B27+NP1+ rats was confirmed immunologically and by mass spectrometry. The NP1 product displaced ∼90% of the 3H-Arg-labeled endogenous peptide fraction in B27+NP1+ spleen cells. Male B27+NP1+ rats had a significantly reduced prevalence of arthritis, compared with B27+NP− males or B27+ males with a control construct, NP2, whereas colitis was not significantly affected by the NP1 transgene. These findings support the hypothesis that B27-related arthritis requires binding of a specific peptide or set of peptides to B27, and they demonstrate a method for efficient transgenic targeting of peptides to the ER

    Scaffold-mediated Nucleation of Protein Signaling Complexes: Elementary Principles

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    Proteins with multiple binding sites play important roles in cell signaling systems by nucleating protein complexes in which, for example, enzymes and substrates are co-localized. Proteins that specialize in this function are called by a variety names, including adapter, linker and scaffold. Scaffold-mediated nucleation of protein complexes can be either constitutive or induced. Induced nucleation is commonly mediated by a docking site on a scaffold that is activated by phosphorylation. Here, by considering minimalist mathematical models, which recapitulate scaffold effects seen in more mechanistically detailed models, we obtain analytical and numerical results that provide insights into scaffold function. These results elucidate how recruitment of a pair of ligands to a scaffold depends on the concentrations of the ligands, on the binding constants for ligand-scaffold interactions, on binding cooperativity, and on the milieu of the scaffold, as ligand recruitment is affected by competitive ligands and decoy receptors. For the case of a bivalent scaffold, we obtain an expression for the unique scaffold concentration that maximally recruits a pair of monovalent ligands. Through simulations, we demonstrate that a bivalent scaffold can nucleate distinct sets of ligands to equivalent extents when the scaffold is present at different concentrations. Thus, the function of a scaffold can potentially change qualitatively with a change in copy number. We also demonstrate how a scaffold can change the catalytic efficiency of an enzyme and the sensitivity of the rate of reaction to substrate concentration. The results presented here should be useful for understanding scaffold function and for engineering scaffolds to have desired properties.Comment: 12 pages, 8 figure
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