244 research outputs found

    Taxonomy and paleobiology of some Middle Cambrian Scenella (Cnidaria) and Hyolithids (Mollusca) from western North America

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    22 p., 10 fig.http://paleo.ku.edu/contributions.htm

    Systematics, paleobiology, and taphonomy of some exceptionally preserved trilobites from Cambrian Lagerstätten of Utah

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    Mid-Cambrian biotas of the Spence, Wheeler, Marjum, and Weeks formations in Utah are exceptionally diverse. Continued collecting has produced additional trilobites here assigned to one new genus, Meniscopsia, and 25 new species. The new species, all known from complete or nearly complete dorsal exoskeletons, are Amecephalus jamisoni, Athabaskia gladei, Bolaspidella jarrardi, Bolaspidella reesae, Burlingia halgedahlae, Coosella kieri, Ehmaniella whitei, Glossopleura campbelli, Glossopleura yatesi, Ithycephalus stricklandi, Kootenia randolphi, Kootenia youngorum, Meniscopsia beebei, Menomonia sahratiani, Modocia comforti, Modocia kohli, Modocia whiteleyi, Norwoodia boninoi, Olenoides skabelundi, Olenoides vali, Polypleuraspis cooperi, Ptychoparella lloydi, Ptychoparella mettae, Zacanthoides liddelli, and Zacanthoides marshalli. Descriptions of two other species, Triadaspis bigeneris and Zacanthoides typicalis, are expanded to include new information from complete dorsal exoskeletons. The ventral cephalic presence of a functional rostral-hypostomal suture in the corynexochoid Zacanthoides marshalli further demonstrates that a fused rostral-hypostomal plate is not a unique defining character of the order Corynexochida, adding to evidence that the Corynexochida may be a polyphyletic taxon. The ventral cephalic presence of a median suture, associated with a rostellum in Norwoodia boninoi, order Ptychopariida, is further evidence for a polyphyletic origin of the median suture, previously cited as a unique apomorphic character defining the order Asaphida, which needs revision. The presence of a mineralized alimentary tract and digestive glands in some specimens of Meniscopsia beebei and Coosella kieri suggests that the gut was fluid filled at the time of burial and that the species were predaceous. Collapsed glabellas are interpreted as further evidence of fluid-filled gut tracts in some of the new species. Many of the articulated trilobites preserved in mid-Cambrian Lagerstätten of Utah were probably buried under rapidly deposited sediment clouds on a storm-prone marine shelf. Occasionally, trilobite clusters were buried. Encrustation of fully articulated individuals with calcitic cone-in-cone deposits in the Wheeler and Marjum formations is a likely consequence of concretionary-type growth within a biofilm shortly after death

    Parent Agreement on Ratings of Children's Attention Deficit/Hyperactivity Disorder and Broadband Externalizing Behaviors

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    Mothers and fathers often disagree in their ratings of child behavior, as evidenced clinically and as supported by a substantial literature examining parental agreement on broadband rating scales. The present study examined mother-father agreement on Diagnostic and Statistical Manual-based symptom-specific ratings of Attention-Deficit/Hyperactivity Disorder (ADHD), as compared to agreement on broadband ratings of externalizing behavior. Based on mother and father ratings of 324 children who participated in the Multimodal Treatment Study of Children with ADHD (MTA), parental agreement was computed and patterns of disagreement examined. Mother-father ratings were significantly correlated; however, a clear pattern of higher ratings by mothers was present. Agreement on attention-deficit/hyperactivity disorder symptom-specific ratings was significantly lower than that for broadband externalizing behaviors and oppositional defiant disorder symptoms. Of several moderator variables tested, parental stress was the only one that predicted the discrepancy in ratings. Disagreement between parents is clinically significant and may pose complications to the diagnostic process

    Exports and Productivity: Comparable Evidence for 14 Countries

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    We use comparable micro level panel data for 14 countries and a set of identically specified empirical models to investigate the relationship between exports and productivity. Our overall results are in line with the big picture that is by now familiar from the literature: Exporters are more productive than non-exporters when observed and unobserved heterogeneity are controlled for, and these exporter productivity premia tend to increase with the share of exports in total sales; there is strong evidence in favour of self-selection of more productive firms into export markets, but nearly no evidence in favour of the learning-by-exporting hypothesis. We document that the exporter premia differ considerably across countries in identically specified empirical models. In a meta-analysis of our results we find that countries that are more open and have more effective government report higher productivity premia. However, the level of development per se does not appear to be an explanation for the observed cross-country differences.exports; productivity; micro data; international comparison

    A global-temporal analysis on Phytophthora sojae resistance-gene efficacy

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    Plant disease resistance genes are widely used in agriculture to reduce disease outbreaks and epidemics and ensure global food security. In soybean, Rps (Resistance to Phytophthora sojae) genes are used to manage Phytophthora sojae, a major oomycete pathogen that causes Phytophthora stem and root rot (PRR) worldwide. This study aims to identify temporal changes in P. sojae pathotype complexity, diversity, and Rps gene efficacy. Pathotype data was collected from 5121 isolates of P. sojae, derived from 29 surveys conducted between 1990 and 2019 across the United States, Argentina, Canada, and China. This systematic review shows a loss of efficacy of specific Rps genes utilized for disease management and a significant increase in the pathotype diversity of isolates over time. This study finds that the most widely deployed Rps genes used to manage PRR globally, Rps1a, Rps1c and Rps1k, are no longer effective for PRR management in the United States, Argentina, and Canada. This systematic review emphasizes the need to widely introduce new sources of resistance to P. sojae, such as Rps3a, Rps6, or Rps11, into commercial cultivars to effectively manage PRR going forward

    Room Temperature Optically and Magnetically Active Edges in Phosphorene Nanoribbons

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    Nanoribbons - nanometer wide strips of a two-dimensional material - are a unique system in condensed matter physics. They combine the exotic electronic structures of low-dimensional materials with an enhanced number of exposed edges, where phenomena including ultralong spin coherence times, quantum confinement and topologically protected states can emerge. An exciting prospect for this new material concept is the potential for both a tunable semiconducting electronic structure and magnetism along the nanoribbon edge. This combination of magnetism and semiconducting properties is the first step in unlocking spin-based electronics such as non-volatile transistors, a route to low-energy computing, and has thus far typically only been observed in doped semiconductor systems and/or at low temperatures. Here, we report the magnetic and semiconducting properties of phosphorene nanoribbons (PNRs). Static (SQUID) and dynamic (EPR) magnetization probes demonstrate that at room temperature, films of PNRs exhibit macroscopic magnetic properties, arising from their edge, with internal fields of ~ 250 to 800 mT. In solution, a giant magnetic anisotropy enables the alignment of PNRs at modest sub-1T fields. By leveraging this alignment effect, we discover that upon photoexcitation, energy is rapidly funneled to a dark-exciton state that is localized to the magnetic edge and coupled to a symmetry-forbidden edge phonon mode. Our results establish PNRs as a unique candidate system for studying the interplay of magnetism and semiconducting ground states at room temperature and provide a stepping-stone towards using low-dimensional nanomaterials in quantum electronics.Comment: 18 pages, 4 figure

    ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices—Summary Article A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to Update the 1998 Pacemaker Guidelines) 11This document was approved by the American College of Cardiology Foundation Board of Trustees in September 2002, the American Heart Association Science Advisory and Coordinating Committee in August 2002, and the North American Society for Pacing and Electrophysiology in August 2002.22The ACC/AHA Task Force on Practice Guidelines makes every effort to avoid any actual or potential conflicts of interest that might arise as a result of an outside relationship or personal interest of a member of the writing panel. Specifically, all members of the writing panel are asked to provide disclosure statements of all such relationships that might be perceived as real or potential conflicts of interest. These statements are reviewed by the parent task force, reported orally to all members of the writing panel at the first meeting, and updated as changes occur. The conflict of interest information for the writing committee members is posted on the ACC, AHA, and NASPE Web sites with the full-length version of the update.33When citing this document, the ACC, the AHA, and NASPE would appreciate the following citation format: Gregoratos G, Abrams J, Epstein AE, Freedman RA, Hayes DL, Hlatky MA, Kerber RE, Naccarelli GV, Schoenfeld MH, Silka MJ, Winters SL. ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices—Summary Article: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to Update the 1998 Pacemaker Guidelines). J Am Coll Cardiol2002;40:1703–19.44Copies: This document is available on the World Wide Web sites of the ACC (www.acc.org) and the AHA (www.americanheart.org). A single copy of the complete guidelines is available by calling 800-253-4636 (US only) or writing the American College of Cardiology, Resource Center, 9111 Old Georgetown Road, Bethesda, MD 20814-1699 (ask for No. 71-0237). To obtain a copy of the Summary Article, ask for reprint No. 71-0236. To purchase additional reprints (specify version and reprint number): up to 999 copies, call 800-611-6083 (US only) or fax 413-665-2671; 1000 or more copies, call 410-528-4426, fax 410-528-4264, or e-mail [email protected](J Am Coll Cardiol 2002;40:1703–19.)66©2002 by the American College of Cardiology Foundation and the American Heart Association, Inc.

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