688 research outputs found

    Circular 52

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    This is the sixth publication in this format on grain performance trials in the Tanana River Valley. The first, published 5 years ago, included the results o f spring cereal-variety tests conducted at Fairbanks and Delta Junction during the 1978 and 1979 growing seasons. The variety-test results from the 1980, 1981, 1982, and 1983 growing seasons were annual publications. Included in this report are a weather summary, the 1984 variety-test results, and a plant-disease section.Introduction -- Standard Bushel Weights and Conversion from English to Metric Units -- Part I: Climatic Data for and Germplasm Evaluation: Tanana Valley Weather Summary: Table 1: Climatic Data for Delta Junction during the 1984 Growing Season, Table 2: Climatic Data for Fairbanks during the 1984 Growing Season; Barley Performance Trials: Table 3: Long-Term Average and Range of Yields for Barley Standard Varieties Grown at Fairbanks and Delta Junction, 1971-1984, Table 4: Barley Variety Trials Conducted at Delta Junction and Fairbanks during the 1984 Growing Season, Variety Descriptions, Table 5: Barley Varieties Tested at Fairbanks and Delta Junction, 1971-1984 -- Oat Performance Trials: Table 6 : Long-Term Average and Range in Yields for Oat Standard Varieties Grow n at Fairbanks and Delta Junction, 1971-1984, Table 7: Oat Variety Trials Conducted at Delta Junction and Fairbanks during the 1984 Growing Season, Variety Descriptions, Table 8 : Oat Varieties Tested at Fairbanks and Delta Junction, 1971-1984 -- Spring Wheat Performance Trials: Table 9: Long-Term Average and Range in Yields for Wheat Standard Varieties Grown at Fairbanks and Delta Junction, 1971-1984, Table 10: W heat Variety Trials Conducted at Fairbanks and Delta Junction during the 1984 Growing Season -- Variety Descriptions: Table 11: W heat Varieties Tested at Fairbanks and Delta Junction, 1971-1984 -- Part II: Plant-Disease Evaluation: Barley Diseases: Table 12: Summary of Diseases Observed on Barley Varieties under Field Conditions in the Delta-Clearwater Area, Snow M old Disease Com plex on W inter W heat and Lawn G ra s s e s, Diseases on O ther C r o p, Diseases O bserved on Crops during the 1984 Growing Season and T heir S ym ptom

    Plumage and ecology of cormorants

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    The paper draws on data attending the etho-ecology of four species of cormorants (Phalacrocoracidae) in support of an hypothesis for the adaptive significance of the predominantly dark plumage of these birds. It is suggested that a dark plumage, primarily by being most receptive to solar radiation, assists cormorants in supplementing metabolic heat for maintenance of normal body temperature. In those cormorants which have white extending over ventral and frontal aspects of the body, it is suggested that this is an adaptation to the feeding situation and that it promotes 'hunting camouflage' through countershading

    Financial rogue waves

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    The financial rogue waves are reported analytically in the nonlinear option pricing model due to Ivancevic, which is nonlinear wave alternative of the Black-Scholes model. These solutions may be used to describe the possible physical mechanisms for rogue wave phenomenon in financial markets and related fields.Comment: 4 papges, 2 figures, Final version accepted in Commun. Theor. Phys., 201

    Natural disturbances and the physiognomy of pine savannas : A phenomenological model

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    Abstract. Question: The decline of the Pinus palustris ecosystems has resulted from anthropogenic influences, such as conversion to pine plantation forestry, agriculture and land development, all of which are closely related to increases in human populations. Other effects, however, have arisen from alterations in disturbance regimes that maintain the structure and function of these ecosystems. How have alterations of the disturbance regime altered the physiognomy of ‘old-growth’ stands, and what are the implications for ecosystem conservation and restoration? Methods: In contrast to models that emphasize close interactions among the vertically complex strata, we develop a conceptual phenomenological model for the physiognomic structure of Pinus palustris stands. We relate two natural disturbances (tropical storms and fire) that affect different stages of the life cycle to different aspects of the physiognomic structure. We then compare overstorey stand structure and ground cover composition of two old-growth longleaf stands near the extremes of different composite disturbance regimes: the Wade Tract (frequent hurricanes and fire) and the Boyd Tract (infrequent hurricanes and long-term fire exclusion). Results: We predict that tropical storms and fires have different effects on stand physiognomy. Tropical storms are periodic, and sometimes intense, whereas fires are more frequent and less intense. Hurricanes directly influence the overstorey via wind-caused damage and mortality, and indirectly influence the herb layer by altering the spatial distribution of shading and litter accumulation. Fire exerts direct effects on juvenile stages and indirect effects on the herb layer via fine fuel consumption and selective mortality of potential competitors of P. palustris juveniles. These differences in effects of disturbances can result in widely different physiognomies for P. palustris stands. Finally, some global climate change scenarios have suggested that changes may occur in tropical storm and fire regimes, altering frequency and severity. Such changes may greatly affect pine stands, and ultimately entire pine savanna ecosystems. Conclusions: Our phenomenological model of disturbance regimes in Pinus palustris old-growth produces very different physiognomies for different disturbances regimes that reflect natural process and human management actions. This model can be used to derive restoration strategies for pine savannas that are linked to reinstitution of important ecological processes rather than specific physiognomic states

    Astronomers for planet Earth: embracing virtual communication induced by the COVID-19 pandemic to help tackle the climate crisis

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    Astronomers for Planet Earth (A4E) is a global collective, whose main goal is to communicate the fragility of our planet from an astronomical perspective. A4E works hard to equally engage with astronomers and educators worldwide, by encouraging the communities to reduce emissions and providing a space to collaborate and share resources. These actions have led to increased sustainability and the incorporation of climate change lessons and activities into teaching and outreach. With the global shift to online communication due to Covid-19, Astronomers for Planet Earth has utilised digital tools in the form of online conferences and seminars, high-impact journal articles, webinars, social media, and video production to engage its audience and grow a membership of around 1300 astronomers in 70 countries around the world. Our article addresses the importance of communicating the climate crisis from an astronomical perspective and explores the successes and challenges of our group's virtual communication with the astronomy community and the general public thus far.Science Communication and Societ

    Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

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    A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

    Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

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    Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

    Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

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    The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter
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