1,690 research outputs found

    Flowering annuals : petunias

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    "Petunias have become one of the most popular flowering annual garden plants. They are relatively free from insect and disease problems, have a long flowering period, are easy to grow, and are available in a wide range of form and color."--First page.R.R. Rothenberger and B. Fick (Department of Horticulture, College of Agriculture)Types of petunias -- Cultural practices -- Varieties -- Starting petunias indoors -- Diseases and insects.Revised 6/90/8M--Page 4

    Origin of atmospheric aerosols at the Pierre Auger Observatory using backward trajectory of air masses

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    The Pierre Auger Observatory is the largest operating cosmic ray observatory ever built. Calorimetric measurements of extensive air showers induced by cosmic rays are performed with a fluorescence detector. Thus, one of the main challenges is the monitoring of the atmosphere, both in terms of atmospheric state variables and optical properties. To better understand the atmospheric conditions, a study of air mass trajectories above the site is presented. Such a study has been done using an air-modelling program well known in atmospheric sciences. Its validity has been checked using meteorological radiosonde soundings performed at the Pierre Auger Observatory. Finally, aerosol concentration values measured by the Central Laser Facility are compared to backward trajectories.Comment: 4 pages, 6 figures -- ECRS'12 European Cosmic Ray Symposium (July, 3-7, 2012) at Moscow, Russi

    Transport Coefficients of Non-Newtonian Fluid and Causal Dissipative Hydrodynamics

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    A new formula to calculate the transport coefficients of the causal dissipative hydrodynamics is derived by using the projection operator method (Mori-Zwanzig formalism) in [T. Koide, Phys. Rev. E75, 060103(R) (2007)]. This is an extension of the Green-Kubo-Nakano (GKN) formula to the case of non-Newtonian fluids, which is the essential factor to preserve the relativistic causality in relativistic dissipative hydrodynamics. This formula is the generalization of the GKN formula in the sense that it can reproduce the GKN formula in a certain limit. In this work, we extend the previous work so as to apply to more general situations.Comment: 15 pages, no figure. Discussions are added in the concluding remarks. Accepted for publication in Phys. Rev.

    Microscopic Theory for the Markovian Decay of Magnetization Fluctuations in Nanomagnets

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    We present a microscopic theory for the phonon-driven decay of the magnetization fluctuations in a wide class of nanomagnets where the dominant energy is set by isotropic exchange and/or uniaxial anisotropy. Based on the Zwanzig-Mori projection formalism, the theory reveals that the magnetization fluctuations are governed by a single decay rate ωc\omega_c, which we further identify with the zero-frequency portion of the associated self-energy. This dynamical decoupling from the remaining slow degrees of freedom is attributed to a conservation law and the discreteness of the energy spectrum, and explains the omnipresent mono-exponential decay of the magnetization over several decades in time, as observed experimentally. A physically transparent analytical expression for ωc\omega_c is derived which highlights the three specific mechanisms of the slowing down effect which are known so far in nanomagnets.Comment: 7 page

    Matched case-control studies: a review of reported statistical methodology

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    Background: Case-control studies are a common and efficient means of studying rare diseases or illnesses with long latency periods. Matching of cases and controls is frequently employed to control the effects of known potential confounding variables. The analysis of matched data requires specific statistical methods. Methods: The objective of this study was to determine the proportion of published, peer-reviewed matched case-control studies that used statistical methods appropriate for matched data. Using a comprehensive set of search criteria we identified 37 matched case-control studies for detailed analysis. Results: Among these 37 articles, only 16 studies were analyzed with proper statistical techniques (43%). Studies that were properly analyzed were more likely to have included case patients with cancer and cardiovascular disease compared to those that did not use proper statistics (10/16 or 63%, versus 5/21 or 24%, P = 0.02). They were also more likely to have matched multiple controls for each case (14/16 or 88%, versus 13/21 or 62%, P = 0.08). In addition, studies with properly analyzed data were more likely to have been published in a journal with an impact factor listed in the top 100 according to the Journal Citation Reports index (12/16 or 69%, versus 1/21 or 5%, P Conclusion: The findings of this study raise concern that the majority of matched case-control studies report results that are derived from improper statistical analyses. This may lead to errors in estimating the relationship between a disease and exposure, as well as the incorrect adaptation of emerging medical literature.</p

    Relating chaos to deterministic diffusion of a molecule adsorbed on a surface

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    Chaotic internal degrees of freedom of a molecule can act as noise and affect the diffusion of the molecule on a substrate. A separation of time scales between the fast internal dynamics and the slow motion of the centre of mass on the substrate makes it possible to directly link chaos to diffusion. We discuss the conditions under which this is possible, and show that in simple atomistic models with pair-wise harmonic potentials, strong chaos can arise through the geometry. Using molecular-dynamics simulations, we demonstrate that a realistic model of benzene is indeed chaotic, and that the internal chaos affects the diffusion on a graphite substrate

    The Central Laser Facility at the Pierre Auger Observatory

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    The Central Laser Facility is located near the middle of the Pierre Auger Observatory in Argentina. It features a UV laser and optics that direct a beam of calibrated pulsed light into the sky. Light scattered from this beam produces tracks in the Auger optical detectors which normally record nitrogen fluorescence tracks from cosmic ray air showers. The Central Laser Facility provides a "test beam" to investigate properties of the atmosphere and the fluorescence detectors. The laser can send light via optical fiber simultaneously to the nearest surface detector tank for hybrid timing analyses. We describe the facility and show some examples of its many uses.Comment: 4 pages, 5 figures, submitted to 29th ICRC Pune Indi
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