2,327 research outputs found

    PBW-deformations of N-Koszul algebras

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    For a quotient algebra UU of the tensor algebra we give explicit conditions on its relations for UU being a PBW-deformation of an NN-Koszul algebra AA. We show there is a one-one correspondence between such deformations and a class of AA_\infty-structures on the Yoneda algebra ExtA(k,k)Ext_A^*(k,k) of AA. We compute the PBW-deformations of the algebra whose relations are the anti-symmetrizers of degree NN and also of cubic Artin-Schelter algebras.Comment: 35 pages. Some minor correction

    Development of a nonstationary flow device for an atmospheric boundary layer wind tunnel

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    Iowa State University researchers are in the process of developing a new wind tunnel. This tunnel will be able to perform a wide range of tests. It will not only be used in an aerodynamic (Aero) test section configuration, but also in an atmospheric boundary layer (ABL) type configuration. It will be able to create a model of the turbulent boundary layer that all structures in the atmosphere are submersed in. The tunnel is designed to utilize both closed return as well as open return tunnel configurations. This will enable the tunnel to reap the benefits of both types of tunnels. Currently most of the ABL studies rely on the assumption that atmospheric velocity variations are adequately modeled by stationary mean and turbulent flow properties. The ISU Aero/ABL tunnel will be able to develop non-stationary flows to help better study and understand this type of phenomena. The primary concern and area of research reported here has been to develop this non-stationary flow device by modeling and testing the design. The results shown reflect that a 107% gust can be achieved by the model, but with some changes to the design, a higher magnitude gust can be achieved

    Wildbook: Crowdsourcing, computer vision, and data science for conservation

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    Photographs, taken by field scientists, tourists, automated cameras, and incidental photographers, are the most abundant source of data on wildlife today. Wildbook is an autonomous computational system that starts from massive collections of images and, by detecting various species of animals and identifying individuals, combined with sophisticated data management, turns them into high resolution information database, enabling scientific inquiry, conservation, and citizen science. We have built Wildbooks for whales (flukebook.org), sharks (whaleshark.org), two species of zebras (Grevy's and plains), and several others. In January 2016, Wildbook enabled the first ever full species (the endangered Grevy's zebra) census using photographs taken by ordinary citizens in Kenya. The resulting numbers are now the official species census used by IUCN Red List: http://www.iucnredlist.org/details/7950/0. In 2016, Wildbook partnered up with WWF to build Wildbook for Sea Turtles, Internet of Turtles (IoT), as well as systems for seals and lynx. Most recently, we have demonstrated that we can now use publicly available social media images to count and track wild animals. In this paper we present and discuss both the impact and challenges that the use of crowdsourced images can have on wildlife conservation.Comment: Presented at the Data For Good Exchange 201

    The Challenges of Pluralism: Locating Religion in a World of Diversity

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    This is a postprint (author's final draft) version of an article published in the journal Social Compass in 2010. The final version of this article may be found at http://dx.doi.org/10.1177/0037768610362406 (login may be required). The version made available in OpenBU was supplied by the author.The author argues that religious pluralism is the normal state of affairs. Religion itself is multi-dimensional, and the several dimensions of religious and spiritual experience can be combined in myriad ways across individual lives. Preliminary findings from new research are presented, detailing modes of spiritual discourse that include mystery, majesty, meaning, moral compassion, and social connection. These dimensions find expression across multiple social institutions. In addition, religion is multi-traditional and organized by plural producers of the goods and services and events that embody and transform religious tradition. Finally, it is argued that religious pluralism must be studied in terms of the structures of power and privilege that allow some religious ideas to be given free voice, but limit the practice of other religious rituals or the gathering of dissident religious communities

    Earthquake Mechanism and Displacement Fields Close to Fault Zones

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    The Sixth Geodesy/Solid Earth and Ocean Physics (GEOP) Research Conference was held on February 4–5, 1974, at the Institute of Geophysics and Planetary Physics, University of California, San Diego, in La Jolla, California. It was attended by about 100 persons. James N. Brune, program chairman, opened the conference and delivered the introductory address, a somewhat extended version of which is printed elsewhere in this issue. Brune's paper and the following summaries of the sessions constitute a report of the conference

    Light Gluino Constituents of Hadrons and a Global Analysis of Hadron Scattering Data

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    Light strongly interacting supersymmetric particles may be treated as partonic constituents of nucleons in high energy scattering processes. We construct parton distribution functions for protons in which a light gluino is included along with standard model quark, antiquark, and gluon constituents. A global analysis is performed of a large set of data from deep-inelastic lepton scattering, massive lepton pair and vector boson production, and hadron jet production at large values of transverse momentum. Constraints are obtained on the allowed range of gluino mass as a function of the value of the strong coupling strength alpha_s(M_Z) determined at the scale of the Z boson mass. We find that gluino masses as small as 10 GeV are admissible provided that alpha_s(M_Z) \ge 0.12. Current hadron scattering data are insensitive to the presence of gluinos heavier than ~ 100 - 150 GeV.Comment: 31 pages, 12 figures, RevTe

    Strengthening the impact of plant genetic resources through collaborative collection, conservation, characterisation, and evaluation: a tribute to the legacy of Dr Clive Francis

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    This paper is a tribute to the legacy of Dr Clive Francis, who directly and indirectly collected >14 000 accessions across 60 genera of pasture, forage, and crop species and their wild relatives around the Mediterranean basin, Eastern Africa, and Central and South Asia from 1973 to 2005. This was achieved by a collaborative approach that built strong interactions between disparate organisations (ICARDA, VIR, CLIMA, and Australian genebanks) based on germplasm exchange, conservation and documentation, capacity building, and joint collection. These activities greatly strengthened Australian pasture, forage, and crop genebanks, and led to widespread germplasm utilisation that has waned in the last 5 years, reflecting changing priorities among industry funding bodies and research providers. This situation must be reversed, given the pivotal role genetic resource collections must play to broaden the genetic and adaptive base of plant breeding, to meet the challenge of feeding an increasing population in a depleting resource base. Because the use of germplasm subsets that facilitate phenotyping will stimulate wider utilisation of genetic resources, we discuss the application of core collection and germplasm selection through habitat characterisation/filtering in Australian collections. Both are valid entry points into large collections, but the latter has the advantage of enabling both trait discovery and investigation of plant adaptation, and because it is based on a priori hypothesis testing, it increases understanding even when the trait of interest is not identified

    The u'g'r'i'z' Standard Star Network

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    We present the 158 standard stars that define the u'g'r'i'z' photometric system. These stars form the basis for the photometric calibration of the Sloan Digital Sky Survey (SDSS). The defining instrument system and filters, the observing process, the reduction techniques, and the software used to create the stellar network are all described. We briefly discuss the history of the star selection process, the derivation of a set of transformation equations for the UBVRcIc system, and plans for future work.Comment: References to URLs in paper have been updated to reflect moved website. Accepted by AJ. 50 pages, including 20 pages of text, 9 tables, and 15 figures. Plain ASCII text versions of Tables 8 and 9 can be found at http://home.fnal.gov/~dtucker/ugriz/index.html (new URL

    The Massive Progenitor of the Possible Type II-Linear Supernova 2009hd in Messier 66

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    We present observations of SN2009hd in the nearby galaxy M66. This SN is one of the closest to us in recent years but heavily obscured by dust, rendering it unusually faint in the optical, given its proximity. We find that the observed properties of SN2009hd support its classification as a possible Type II-L SN, a relatively rare subclass of CC-SNe. High-precision relative astrometry has been employed to attempt to identify a SN progenitor candidate, based on a pixel-by-pixel comparison between HST F555W and F814W images of the SN site prior to explosion and at late times. A progenitor candidate is identified in the F814W images only; this object is undetected in F555W. Significant uncertainty exists in the astrometry, such that we cannot definitively identify this object as the SN progenitor. Via insertion of artificial stars into the pre-SN HST images, we are able to constrain the progenitor's properties to those of a possible supergiant, with M(F555W)0>-7.6 mag and (V-I) 0>0.99 mag. The magnitude and color limits are consistent with a luminous RSG; however, they also allow for the possibility that the star could have been more yellow than red. From a comparison with theoretical massive-star evolutionary tracks, which include rotation and pulsationally enhanced mass loss, we can place a conservative upper limit on the initial mass for the progenitor of <20 M_sun. If the actual mass of the progenitor is near the upper range allowed by our derived mass limit, then it would be consistent with that for the identified progenitors of the SNII-L 2009kr and the high-luminosity SNII-P 2008cn. The progenitors of these three SNe may possibly bridge the gap between lower-mass RSG that explode as SNeII-P and LBV, or more extreme RSG, from which the more exotic SNeII-n may arise. Very late-time imaging of the SN2009hd site may provide us with more clues regarding the true nature of its progenitor.Comment: 19 pages, 9 figures, 3 tables, accepted for publication in Ap
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