302 research outputs found

    Synthesis and Evaluation of Mixed Efficacy Mu Opioid Receptor (MOR), Delta Opioid Receptor (DOR) Peptidomimetic Ligands.

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    Reported here is a structure activity relationship (SAR) study on a series of mixed efficacy mu opioid receptor (MOR) agonist/delta opioid receptor (DOR) antagonist ligands featuring a tetrahydroquinoline (THQ) scaffold. A diverse set of substitutions at the 6-position of the THQ core has revealed a number of important trends. Attachment of this pendant at a basic nitrogen resulted in a number of analogues that showed superior binding affinity and potency at MOR, with improved binding affinity at the kappa opioid receptor (KOR). In particular, N-acetylated, tetrahydroisoquinoline analogue 102 showed equal, subnanomolar binding affinity for MOR, DOR and KOR, with a low nanomolar EC50 at MOR and no stimulation at DOR. 102, in addition to isoindoline analogue 86, were also shown to produce dose dependent antinociception in the mouse warm water tail withdrawal (WWTW) assay, with both compounds having a total duration of action comparable to morphine, an improvement on lead peptidomimetic 1. Substitution of the THQ aniline with a variety of heteroatoms was found to maintain subnanomolar MOR binding affinity and high efficacy, although only thiochroman analogue 214 was found to produce a dose dependent antinociceptive effect in the WWTW assay, with a duration of action comparable to 86 and 102. Expansion or contraction of the THQ ring system was detrimental to the overall desired MOR agonist/DOR antagonist profile, with MOR potency being particularly affected. A 3-step synthesis of Boc-2’,6’-dimethyl-L-tyrosine featuring a microwave-assisted Negishi coupling is also described, which led to the expedient synthesis of novel tyrosine analogues that were incorporated into the peptidomimetic scaffold. Of particular interest is 2’,6’-dichloro-L-tyrosine intermediate 243, which may be useful for the development of peptidomimetics with reduced liability for oxidative metabolism on the aryl methyl groups, and carboxamido peptidomimetic 251, which shows a total duration of action in vivo that is comparable to lead compound 1. An alternative series of peptidomimetics featuring a piperidine or piperazine core is also discussed. In this series, it was found that an increase in the length of the hydrophobic chain at position 4 corresponds to an improved efficacy at MOR.PhDMedicinal ChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120867/1/ambender_1.pd

    A Fresh Look at Energy, Materials, and Labor in Agriculture

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    An understanding of agriculture's energy, material, and labor requirements is essential for achieving economic and ecological sustainability, and for assessing the effectiveness of relevant policy decisions (biofuel subsidies, regulations, labeling, etc.). Previous studies of energy, materials, and labor use in farming have been based on either unverified voluntary reporting or test plots, rather than on the high-resolution measurements of mass and energy flows. Here we present a recursive analysis of 1.25 million data points describing in unprecedented detail the resource transactions on a 60 ha farm functioning for over 6 years. This analysis highlights the importance of accounting for all types of materials, as well as capital equipment, non-field labor, and commuting. The superior energy efficiency of the farm's energy-saving methods, including green manure, crop rotation, composting, and short-duration grazing -- compared with conventional methods -- persists even when the higher labor requirements are taken into account. One of the farm's methods, however -- the use of horses for traction -- is shown to be highly inefficient compared with mechanical tractors

    Temporal invariance of social-ecological catchments

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    Natural resources such as waterbodies, public parks, and wildlife refuges attract people from varying distances on the landscape, creating “social-ecological catchments.” Catchments have provided great utility for understanding physical and social relationships within specific disciplines. Yet, catchments are rarely used across disciplines, such as its application to understand complex spatiotemporal dynamics between mobile human users and patchily distributed natural resources. We collected residence ZIP codes from 19,983 angler parties during 2014–2017 to construct seven angler–waterbody catchments in Nebraska, USA. We predicted that sizes of dense (10% utilization distribution) and dispersed (95% utilization distribution) angler–waterbody catchments would change across seasons and years as a function of diverse resource selection among mobile anglers. Contrary to expectations, we revealed that catchment size was invariant. We discuss how social (conservation actions) and ecological (low water quality, reduction in species diversity) conditions are expected to impact landscape patterns in resource use. We highlight how this simple concept and user-friendly technique can inform timely landscape-level conservation decisions within coupled social-ecological systems that are currently difficult to study and understand

    Environmentally Responsible Aviation N plus 2 Advanced Vehicle Study

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    This is the Northrop Grumman final report for the Environmentally Responsible Aviation (ERA) N+2 Advanced Vehicle Study performed for the National Aeronautics and Space Administration (NASA). Northrop Grumman developed advanced vehicle concepts and associated enabling technologies with a high potential for simultaneously achieving significant reductions in emissions, airport area noise, and fuel consumption for transport aircraft entering service in 2025. A Preferred System Concept (PSC) conceptual design has been completed showing a 42% reduction in fuel burn compared to 1998 technology, and noise 75dB below Stage 4 for a 224- passenger, 8,000 nm cruise transport aircraft. Roadmaps have been developed for the necessary technology maturation to support the PSC. A conceptual design for a 55%-scale demonstrator aircraft to reduce development risk for the PSC has been completed

    The C. elegans CHP1 homolog, pbo-1, functions in innate immunity by regulating the pH of the intestinal lumen

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    This work is licensed under a Creative Commons Attribution 4.0 International License.Caenorhabditis elegans are soil-dwelling nematodes and models for understanding innate immunity and infection. Previously, we developed a novel fluorescent dye (KR35) that accumulates in the intestine of C. elegans and reports a dynamic wave in intestinal pH associated with the defecation motor program. Here, we use KR35 to show that mutations in the Ca2+-binding protein, PBO-1, abrogate the pH wave, causing the anterior intestine to be constantly acidic. Surprisingly, pbo-1 mutants were also more susceptible to infection by several bacterial pathogens. We could suppress pathogen susceptibility in pbo-1 mutants by treating the animals with pH-buffering bicarbonate, suggesting the pathogen susceptibility is a function of the acidity of the intestinal pH. Furthermore, we use KR35 to show that upon infection by pathogens, the intestinal pH becomes neutral in a wild type, but less so in pbo-1 mutants. C. elegans is known to increase production of reactive oxygen species (ROS), such as H2O2, in response to pathogens, which is an important component of pathogen defense. We show that pbo-1 mutants exhibited decreased H2O2 in response to pathogens, which could also be partially restored in pbo-1 animals treated with bicarbonate. Ultimately, our results support a model whereby PBO-1 functions during infection to facilitate pH changes in the intestine that are protective to the host

    Constraints on H_0 from the Central Velocity Dispersions of Lens Galaxies

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    We employ Schwarzschild's method of orbit modeling to constrain the mass profiles of the central lens galaxies in Q0957+561 and PG 1115+080. We combine the measured central projected stellar velocity dispersions of these galaxies with the self-similar radial profiles of the rms velocity and of the Gauss-Hermite moment h_4 observed in nearby galaxies for 0 < R < 2 R_eff. For Q0957+561, we find a 16% uncertainty in the galaxy mass, and formal 2-sigma limits on the Hubble constant of H_0 = (61 +13/-15) km/s/Mpc. For PG 1115+080, we find that none of the viable lens models can be ruled out, so that H_0 is not yet strongly constrained by this system.Comment: Revised version accepted by ApJ: slightly modified results for both lens sytems. 18 pages, with 7 inline Postscript figures, LaTeX, aaspp4.sty; postscript paper w/figs (490 kb) also available at http://cfa-www.harvard.edu/~romanow/orbit.post.v2.ps.g

    An Approach to Measuring Step Excrescence Effects in the Presence of a Pressure Gradient

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    An experimental study was undertaken to determine the effects of step excrescences on boundary layer transition using a unique ground test facility in which the test model was propelled though still air. The models used were designed to have a nominally constant pressure gradient so that the results would be relevant to laminar flow aircraft whose wings often have long runs of mildly favorable pressure gradient. The models had an integrated continuously adjustable two-dimensional step, which could be adjusted to be forward-facing or aft-facing. The large model was used to increase the Reynolds numbers examined so that the results are applicable to laminar flow flight vehicles. Multiple measurement methods, including Preston tubes, hot wires, accelerometers, a boundary layer traverse, and static pressure taps were used to provide comparison data, and to add to the physical understanding of the results. The propelled-model test approach required that the instrumentation be self-contained and ride along with the model as the carrier vehicle moved down the test track. Due to the relatively short times available for data-taking (approximately 15-30 seconds per run), the initialization and data analysis techniques had to be tailored for this application

    POX 52: A Dwarf Seyfert 1 Galaxy With An Intermediate-Mass Black Hole

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    We describe new optical images and spectra of POX 52, a dwarf galaxy with an active nucleus that was originally detected in the POX objective-prism survey. While POX 52 was originally thought to be a Seyfert 2 galaxy, the new data reveal an emission-line spectrum very similar to that of the dwarf Seyfert 1 galaxy NGC 4395, with broad components to the permitted line profiles, and we classify POX 52 as a Seyfert 1 galaxy. The host galaxy appears to be a dwarf elliptical, and its brightness profile is best fit by a Sersic model with an index of 3.6+/-0.2 and a total magnitude of M_V = -17.6. Applying mass-luminosity-linewidth scaling relations to estimate the black hole mass from the broad H-beta linewidth and nonstellar continuum luminosity, we find M_BH ~ 1.6x10^5 solar masses. The stellar velocity dispersion in the host galaxy, measured from the Ca II 8498, 8542 Angstrom lines, is 36+/-5 km/s, also suggestive of a black hole mass of order 10^5 solar masses. Further searches for active nuclei in dwarf galaxies can provide unique constraints on the demographics of black holes in the mass range below 10^6 solar masses.Comment: 11 pages. To appear in Ap
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