25,250 research outputs found
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Selecting and Characterizing Tree-Ring Chronologies for Dendroclimatic Analysis
No full textA widely spaced grid of tree-ring chronologies most suitable for dendroclimatic analysis of western North America is selected objectively on the basis of 1) numbers in the sample, length in years, and site locations, 2) statistical characteristics of the chronologies, and 3) correlation of chronologies with those on neighboring sites. The chronology statistics are then analyzed to characterize the quality of the selected set. The procedures used in this study are recommended for future climatic analysis to assure objectivity in the selection of quality tree-ring data and to allow comparisons of the statistics for new chronologies to the established data sets.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
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Interpretation of Cross Correlation Between Tree-Ring Series
No full textThis item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
David Kalisch, der Vater des Kladderadatsch, der Begründer der Berliner Posse
No full textDAVID KALISCH, DER VATER DES KLADDERADATSCH, DER BEGRÜNDER DER BERLINER POSSE
David Kalisch, der Vater des Kladderadatsch, der Begründer der Berliner Posse / Ring, Max (Public Domain) ( - )
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How robust is the ring stain for evaporating suspension droplets?
No full textThe ring stain is commonly seen when droplets containing particles, such as coffee, are left to dry on a surface: a pinned contact line leads to outward radial flow, which is enhanced by the diverging evaporative flux at the contact line. As shown by Deegan et al. (1997) particles are swept outwards in this flow and create a ring which grows according to a simple power law with time. The final dried width and height of the ring should also be given by power laws of concentration, with both exponent equal to 0.5 provided all particles are in the ring, and the packing factor and ring profile are constant. We use suspensions of polystyrene particles in water with sizes ranging from 200 to 500 nm and initial concentrations c 0 from 0.009% to 1% deposited on glass substrates to investigate these scaling predictions. We vary the drying rate from 0.5 to 5 nl/s using humidity and reduced pressure, use a range of substrates to vary the initial contact angle between 5° and 35°, and invert the droplets to change the direction of gravity. We find that for all but the very lowest pressures, the ring height follows the predicted power law, with exponent equal to 0.50 ± 0.04 and the ring width having an exponent of 0.33 ± 0.05. The discrepancy between the measured and predicted width exponent is accounted for by an observed variation of droplet radius with concentration, and the presence of particles in the center of the droplet. In addition, for low pressures (fast evaporation) the scaling laws no longer hold: the ring is much narrower and there is significant deposition in the center of the droplet, possibly due to reduced particle-enhanced pinning
Ring, David O.
No full textCarte de Visite of Sergeant David O. Ring, 3rd Maine Infantry, Company D; From the MacDonald Collectionhttps://digitalmaine.com/arc_civilwarportraits/2656/thumbnail.jp
Ring, David O.
No full textCarte de Visite of Sergeant David O. Ring, 3rd Maine Infantry, Company D; From the MacDonald Collectionhttps://digitalmaine.com/arc_civilwarportraits/2656/thumbnail.jp
A study of the ring opening metathesis polymerization of polycyclic aromatic monomers and cyclopentenes with well defined initiators
No full textThis thesis describes studies into the ring opening metathesis polymerisation (ROMP) of polycyclic aromatic monomers and cyclopentenes. Chapter 1 reviews general aspects of ring opening metathesis polymerisation of relevance to the themes of this thesis. Chapter 2 describes the synthesis of polycyclic aromatic monomers, the endo and the exo Diels-Alder adducts of acenaphthylene and cyclopentadiene. Chapter 3 reports a study on the polymerisation of these monomers using well defined initiators and classical catalyst systems. Chapter 4 describes the synthesis of a substituted cyclopentene. Chapter 5 reports an investigation of polymerisation of cyclopentene using a variety of well defined initiators of general formula M(=NAr)(- OR)(_2)(=CHR) where M=Mo or W. Chapter 6 presents a study on the polymerisation of a substituted cyclopentene, 4-methylcyclopentene, using a series of well defined initiators, and the characterisations of the polymers obtained using infrared, (^1)H, and (^13)C n.m.r. spectroscopy, differential scanning calorimetry, and gel permeation chromatography and an analysis of detailed microstructure with respect to meso/racemic configurations in the polymer chain. Finally, Chapter 7 summarises the conclusions and makes some suggestions for future work
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Tree-Ring Evidence for Climatic Changes in Western North America From 1500 A.D. to 1940 A.D.
No full text1964 Annual Report to the United States Weather Bureau, Department of Commerce, Washington 25, D.C. / Project: Dendroclimatic History of the United States. OC 406. Grant Cwb-10798 / December 31, 1964Introduction: The details of the climatic history of the United States during recent centuries are not known. In this period, as in more ancient times, there is much indirect evidence of significant changes of climate. Dendroclimatic analysis represents an especially promising source of information on the chronology and character of such climatic changes, especially those in the semiarid regions of western North America. It is the purpose of this report to present: (1) some recent analyses of the climatic factors influencing ring growth; (2) a brief discussion of the current theory concerning the model of tree growth and climate and (3) a first approximation of synoptic dendroclimatological patterns from 1500 A.D. to 1940 A.D. using 26 selected tree-ring chronologies from western North America. This material is being circulated to professionals in related fields in hopes that they may compare these results with their own findings and make appropriate criticisms. The authors welcome any suggestions, especially those pertaining to correlation or lack of correlation of the maps with other lines of evidence. The paper is to be presented at the VII International Congress of the International Association for Quaternary Research which meets at Boulder, Colorado, during August of 1965. The analyses of the tree growth relationships were sponsored in part by the National Geographic Society and the U. S. Department of Interior, National Park Service, through the Wetherill Mesa Archeological Project. The authors are indebted to past and present staff at the Laboratory of Tree-Ring Research for the development of the regional tree-ring chronologies, and to the Numerical Analysis Laboratory, The University of Arizona, for free computing time and services. They are also indebted to James A. Erdman, Maurice E. Cooley, Nicholas Matelas, and Julie McMahan, who assisted in various phases of the project.This item is part of the Natural History Reports collection. It was digitized from a physical copy provided by the Laboratory of Tree-Ring Research at The University of Arizona. For more information about items in this collection, please contact the Lab's Curator, (520) 621-1608 or see http://ltrr.arizona.edu/collection
Measurement Based Reconfigurations in Optical Ring Metro Networks
No full textSingle-hop wavelength division multiplexing (WDM) optical ring networks operating in packet mode are one of themost promising architectures for the design of innovative metropolitan network (metro) architectures. They permit a cost-effective design, with a good combination of optical and electronic technologies, while supporting features like restoration and reconfiguration that are essential in any metro scenario. In this article, we address the tunability requirements that lead to an effective resource usage and permit reconfiguration in optical WDM metros.We introduce reconfiguration algorithms that, on the basis of traffic measurements, adapt the network configuration to traffic demands to optimize performance. Using a specific network architecture as a reference case, the paper aims at the broader goal of showing which are the advantages fostered by innovative network designs exploiting the features of optical technologies
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A Chi-Square Test for the Association and Timing of Tree Ring-Daily Weather Relationships: A New Technique for Dendroclimatology
No full textThis study introduces a new analytical procedure based on the chi-square (x²) statistic to evaluate tree- ring weather relationships. An iterative x² method, developed previously for relating annual crop production to daily values of meteorological measurements, is applied to tree-ring data and compared to results obtained from correlation and bootstrapped response function analyses. All three analytical procedures use a southern Arizona chronology (Pinus arizonica Engelm.) and the latter two use monthly average meteorological data. The x² analysis revealed most of the relationships exhibited by the correlation and response function analyses as well as new linear and nonlinear associations. In addition, cardinal values were obtained that define daily thresholds of the meteorological variables at which the limitation to growth becomes significant. Some of the associations are plausible from the physical system but require more study to confirm or refute a real cause and effect. A few associations appear to be too late in the season or too early in the previous year to affect ring width. We recommend that this x² technique be added to the existing dendroclimatic procedures because it reveals many more possible cause and effect relationships.This item is part of the Tree-Ring Research (formerly Tree-Ring Bulletin) archive. It was digitized from a physical copy provided by the Laboratory of Tree-Ring Research at The University of Arizona. For more information about this peer-reviewed scholarly journal, please email the Editor of Tree-Ring Research at [email protected]
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