3,289 research outputs found

    Greenhouse gas reduction and other benefits of biogas upgrading

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    Biogas obtained from anaerobic digestion of livestock manure is a complex mixture containing ~60% methane (CH4) and other less valuable gases. Upgrading the biogas to reduce contaminants and increase the CH4 concentration is advantageous for several reasons

    What are the potential emissions from engine-generation sets?

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    Biogas is generated from anaerobic digestion of manure and organic wastes. It primarily consists of methane (50-70%), carbon dioxide (25-50%) and water vapor (1-5%). Depending on the feedstock and anaerobic digester conditions, biogas may also contain nitrogen gas (0-5%), hydrogen sulfide (0-7,500 ppm), and ammonia (0-500 ppm). Others volatiles and particulates are trace-level components of biogas

    Hydrogen Sulfide Removal at Spruce Haven Farm, LLC Case Study

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    Spruce Haven Farm, LLC, managed by Doug Young, is located in Cayuga County, New York. The farm herd comprised of 3,360 Holsteins and milks ~1,500 cows. Digester construction began in Spring 2014, with the system operating by October 2014. See “Anaerobic Digestion at Spruce Haven Farm, LLC: Case Study” for more information

    Hydrogen Sulfide Removal at Sunnyside Farms, Inc. Case Study

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    Sunnyside Farms, Inc., managed by Neil and Greg Rejman, is located in Scipio Center, New York. The farm milks ~4,200 cows. The digester was commissioned in May 2009. See “Anaerobic Digestion at Sunnyside Farms, Inc.: Case Study” for more informatio

    Convex Rank Tests and Semigraphoids

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    Convex rank tests are partitions of the symmetric group which have desirable geometric properties. The statistical tests defined by such partitions involve counting all permutations in the equivalence classes. Each class consists of the linear extensions of a partially ordered set specified by data. Our methods refine existing rank tests of non-parametric statistics, such as the sign test and the runs test, and are useful for exploratory analysis of ordinal data. We establish a bijection between convex rank tests and probabilistic conditional independence structures known as semigraphoids. The subclass of submodular rank tests is derived from faces of the cone of submodular functions, or from Minkowski summands of the permutohedron. We enumerate all small instances of such rank tests. Of particular interest are graphical tests, which correspond to both graphical models and to graph associahedra

    Reference frames in allocentric representations are invariant across static and active encoding

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    An influential model of spatial memory the so-called reference systems account proposes that relationships between objects are biased by salient axes ("frames of reference") provided by environmental cues, such as the geometry of a room. In this study, we sought to examine the extent to which a salient environmental feature influences the formation of spatial memories when learning occurs via a single, static viewpoint and via active navigation, where information has to be integrated across multiple viewpoints. In our study, participants learned the spatial layout of an object array that was arranged with respect to a prominent environmental feature within a virtual arena. Location memory was tested using judgments of relative direction. Experiment 1A employed a design similar to previous studies whereby learning of object-location information occurred from a single, static viewpoint. Consistent with previous studies, spatial judgments were significantly more accurate when made from an orientation that was aligned, as opposed to misaligned, with the salient environmental feature. In Experiment 1B, a fresh group of participants learned the same object-location information through active exploration, which required integration of spatial information over time from a ground-level perspective. As in Experiment 1A, object-location information was organized around the salient environmental cue. Taken together, the findings suggest that the learning condition (static vs. active) does not affect the reference system employed to encode object-location information. Spatial reference systems appear to be a ubiquitous property of spatial representations, and might serve to reduce the cognitive demands of spatial processing

    Infrared interferometry to spatially and spectrally resolve jets in X-ray binaries

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    Infrared interferometry is a new frontier for precision ground based observing, with new instrumentation achieving milliarcsecond (mas) spatial resolutions for faint sources, along with astrometry on the order of 10 microarcseconds. This technique has already led to breakthroughs in the observations of the supermassive black hole at the Galactic centre and its orbiting stars, AGN, and exo-planets, and can be employed for studying X-ray binaries (XRBs), microquasars in particular. Beyond constraining the orbital parameters of the system using the centroid wobble and spatially resolving jet discrete ejections on mas scales, we also propose a novel method to discern between the various components contributing to the infrared bands: accretion disk, jets and companion star. We demonstrate that the GRAVITY instrument on the Very Large Telescope Interferometer (VLTI) should be able to detect a centroid shift in a number of sources, opening a new avenue of exploration for the myriad of transients expected to be discovered in the coming decade of radio all-sky surveys. We also present the first proof-of-concept GRAVITY observation of a low-mass X-ray binary transient, MAXI J1820+070, to search for extended jets on mas scales. We place the tightest constraints yet via direct imaging on the size of the infrared emitting region of the compact jet in a hard state XRB.Comment: 12 Pages, 3 figures, accepted for publication in MNRA

    Lineage-Specific Transcriptional Profiles of Symbiodinium spp. Unaltered by Heat Stress in a Coral Host

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    Dinoflagellates of the genus Symbiodinium form an endosymbiosis with reef building corals, in which photosynthetically derived nutrients comprise the majority of the coral energy budget. An extraordinary amount of functional and genetic diversity is contained within the coral-associated Symbiodinium, with some phylotypes (i.e., genotypic groupings), conferring enhanced stress tolerance to host corals. Recent advances in DNA sequencing technologies have enabled transcriptome-wide profiling of the stress response of the cnidarian coral host; however, a comprehensive understanding of the molecular response to stress of coral-associated Symbiodinium, as well as differences among physiologically susceptible and tolerant types, remains largely unexplored. Here, we examine the transcriptome-wide response to heat stress via RNA-Seq of two types of Symbiodinium, the putatively thermotolerant type D2 and the more susceptible type C3K, resident within the same coral host species, Acropora hyacinthus. Contrary to previous findings with coral hosts, we find no detectable change in gene expression across the dinoflagellate transcriptome after 3 days of elevated thermal exposure, despite physical evidence of symbiosis breakdown. However, hundreds of genes identified as orthologs between the C and D types exhibited significant expression differences within treatments (i.e., attributable solely to type, not heat exposure). These include many genes related to known thermotolerance mechanisms including heat shock proteins and chloroplast membrane components. Additionally, both the between-treatment similarities and between-type differences remained pervasive after 12-18 months of common garden acclimation and in mixed Symbiodinium assemblages within the same coral host colony
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