3,474 research outputs found
A model-independent analysis of final-state interactions in \bar B_{d/s}^0 --> J/psi pi pi
Exploiting -meson decays for Standard Model tests and beyond requires a
precise understanding of the strong final-state interactions that can be
provided model-independently by means of dispersion theory. This formalism
allows one to deduce the universal pion-pion final-state interactions from the
accurately known phase shifts and, in the scalar sector, a
coupled-channel treatment with the kaon-antikaon system. In this work an
analysis of the decays and is presented. We find very good agreement with the data up
to 1.05 GeV with a number of parameters reduced significantly compared to a
phenomenological analysis. In addition, the phases of the amplitudes are
correct by construction, a crucial feature when it comes to studies of
violation in heavy-meson decays.Comment: 25 pages, 6 figures, version published in JHE
Electrokinetic flow of aqueous electrolyte in amorphous silica nanotubes
We study the pressure-driven flow of aqueous NaCl in amorphous silica nanotubes using nonequilibrium molecular dynamics simulations featuring both polarizable and non-polarizable molecular models. Different pressures, electrolyte concentrations and pore sizes are examined. Our results indicate a flow that deviates considerably from the predictions of Poiseuille fluid mechanics. Due to preferential adsorption of the different ionic species by surface SiO! or SiOH groups, we find that a significant electric current is generated, but with opposite polarities using polarizable vs. fixed charge models for water and ions, emphasizing the need for careful parameterization in such complex systems. We also examine the influence of partial deprotonation of the silica surface, and we find that much more current is generated in a dehydrogenated nanopore, even though the overall efficiency remains low. These findings indicate that different methods of nanopore preparation, which can produce a range of surface properties, should be examined more closely in the related experimental methods to generate electrokinetic current
Linkind Deadwood Inhabiting Fungi to Carbon Dioxide Flux of Decomposing Coarse Woody Debris
The decomposition of wood is driven by a combination of abiotic and biotic factors, the most influential of them all are fungi. These decomposer fungi use the wood for food, digesting woody material to absorb nutrients and release carbon dioxide. Fungi are the primary drivers of decomposition in most terrestrial ecosystems; thus, the rate and degree of decomposition are greatly dependent on the community of fungi found on woody debris. However, little is known about which fungi decompose woody debris most efficiently. This study aims to investigate the decomposer fungi in the Bear Brook Watershed via molecular techniques and quantify their rates of decomposition to understand which fungi are the most effective decomposers
Effect of Field Direction on Electrowetting in a Nanopore
We manifest a significant influence of field direction and polarity on surface wetting, when the latter is tuned by application of an external electric field. Thermodynamics of field-induced filling of hydrocarbon-like nanopores with water is studied by open ensemble molecular simulation. Increased field strength consistently results in water-filling and electrostriction in hydrophobic nanopores. A threshold field commensurate with surface charge density of about one elementary charge per 10 nm2 suffices to render prototypical paraffin surfaces hydrophilic. When a field is applied in the direction perpendicular to the confining walls, the competition between orientational polarization and angle preferences of interfacial water molecules relative to the walls results in an asymmetric wettability of opposing surfaces (Janus interface). Reduction of surface free energy observed upon alignment of confinement walls with field direction suggests a novel mechanism whereby the applied electric field can operate selectively on water-filled nanotubes while empty ones remain unaffected
Beauties of Nature: Flower and Landscape Gardening in Europe, 1700-1850
"Beauties of Nature" traces changes in taste from valuing grandiose formality to emulating nature, and changes in the study of botany from simple observation to a modern science. But it also traces changes in who the people were who practiced flower gardening and landscaping, from soley upper class men to a much wider array of both men and women.http://deepblue.lib.umich.edu/bitstream/2027.42/120291/1/Beauties_of_Nature_11.pd
Investigations on pathogenicity, invasion biology and population dynamics of the Pine Wood Nematode Bursaphelenchus xylophilus (Steiner und Buhrer 1934) Nickle 1970 in European conifers
Ziel der Arbeit war es, den Wirtspflanzenstatus EuropĂ€ischer Koniferen gegenĂŒber B. xylophilus zu klĂ€ren und die Wechselbeziehung zwischen Nematoden, WirtsbĂ€umen und Temperatur zu untersuchen.Inokulationsversuche wurden mit einer Population von 2400 bis 4000 Nematoden pro Pflanze an drei bis vier Jahre alten Schösslingen im GewĂ€chshaus und in Klimakammern durchgefĂŒhrt. Die Versuche erfolgten bei einer Temperatur von 25°C, sofern nicht verschiedene TemperatureinflĂŒsse untersucht wurden. Um die Entwicklung der Kiefernwelke zu bestimmen, wurde die Welke in sechs Klassen bonitiert und zusĂ€tzlich die Wassergehalte von Spross und Nadeln gemessen. Um den Einfluss von B. xylophilus auf die MortalitĂ€t von P. sylvestris zu untersuchen, wurden insgesamt 140 Schösslinge mit sieben unterschiedlichen Populationsdichten inokuliert: 100, 300, 800, 2400, 4000, 6000, 10000 Nematoden. Die Inokulumdichte hatte keinen Einfluss auf die MortalitĂ€tsrate. Sie war mit 70 % bis 90 % generell hoch. Vier Wochen nach Inokulation konnte ein Zusammenhang zwischen hoher Inokulationsdichte und hoher Populationsdichte in Schösslingen festgestellt werden. Im Wirtspflanzen-Screening von 13 Koniferenarten konnten die Arten P. sylvestris, P. cembra, P. nigra, P. strobus, P. pinaster, P. radiata, P. mugo and Larix decidua als Wirte fĂŒr die B. xylophilus-Isolate aus Portugal, China und Nordamerika bestĂ€tigt werden. L. kaempferi war moderat anfĂ€llig gegen B. xylophilus. P. pinea wies eine moderate AnfĂ€lligkeit fĂŒr das portugiesische B. xylophilus-Isolat auf. P. abies und P. halepensis wiesen geringe Populationsdichten von B. xylophilus vier Wochen nach Inokulation auf. B. xylophilus konnte allerdings aus abgestorbenen BĂ€umen nicht mehr reisoliert werden. A. alba war keine Wirte fĂŒr den Kiefernholznematoden. Migration und Populationsdynamik von B. xylophilus wurden in P. sylvestris Schösslingen untersucht. Dazu wurden die kompletten Pflanzen in 17 Segmente unterteilt. Nematoden wurden nach Inokulation aus Schösslingen an neun Probenterminen wĂ€hrend eines Zeitraumes von 27 Tagen aus allen Segmenten extrahiert. Nach sechs Tagen konnten in allen Pflanzenteilen Nematoden nachgewiesen werden. Nematoden im Schössling erreichten drei Populationsspitzen 12, 19 und 27 Tage nach der Inokulation. Die Ergebnisse deuten darauf hin, dass B. xylophilus sich zunĂ€chst im Wirt ausbreitet und danach eine Population aufbaut. Vier aufeinanderfolgende Stadien der Invasion wurden unterschieden: (1) FrĂŒhe Ausbreitung (2) Verbreitung und Besiedlung aller Pflanzenteile, (3) Populationsaufbau und (4) RĂŒckzug in das Wurzelsystem. FĂŒr Untersuchungen zum Einfluss der Temperatur auf die Populationsdynamik von B. xylophilus und auf die PathogenitĂ€t gegenĂŒber P. sylvestris, L. decidua and P. abies wurden Schösslinge mit Nematoden inokuliert. An sieben Probenterminen wurden Nematoden innerhalb eines Zeitraumes von 61 Tagen aus Spross- und Wurzelteilen extrahiert. Die Versuche wurden in Klimakammern bei Temperaturen von 15°C, 20°C und 25°C durchgefĂŒhrt. Die Temperatur hatte einen Einfluss auf die Populationsdynamik von B. xylophilus in beiden anfĂ€lligen Wirtsarten. Nematoden entwickelten sich nicht in P. abies. Die Temperatur hatte keinen Effekt auf die PathogenitĂ€t des Nematoden. Die maximale MortalitĂ€t wurde bei Ăberschreiten von 20°C in P. sylvestris und L. decidua festgestellt. Keine der Koniferenarten zeigte Welkesymptome bei 15°C. Die Population in P. sylvestris erreichte mit 4000 Nematoden pro Gramm Trockenmasse höhere Dichten bei 25°C als bei 20°C. Daraus kann abgeleitet werden, dass die irreversible Welke in P. sylvestris durch eine Schwellenpopulation von B. xylophilus induziert wird.
The objectives of the present study were to identify potential European host trees for the Pine Wood Nematode (PWN) Bursaphelenchus xylophilus and to investigate the interrelationship between PWN, host trees and temperature. Inoculation experiments with a life stage mixture of 2400 to 4000 B. xylophilus per sapling were conducted with three to four year old saplings in greenhouse and climate chambers adjusted at 25 °C. To evaluate the development of Pine Wilt Disease (PWD), symptoms were assessed in six wilt classes and water content of wood and needles were recorded. Nematodes were extracted from shoots and roots using a modified Baermann funnel technique. To determine the effect of B. xylophilus on mortality of Pinus sylvestris, nematodes were inoculated in 140 saplings with seven densities: 100, 300, 800, 2400, 4000, 6000, 10000. Nematodes were extracted four and twelve weeks after inoculation or at plant death if that occurred before end of experiment. Inoculum densities had no influence on mortality rate which was in general high (70-90 %). Higher population densities in saplings after four weeks were related to higher inoculum densities. After screening 13 conifer species, Pinus sylvestris, Pinus cembra, Pinus nigra, Pinus strobus, Pinus pinaster, Pinus radiata, Pinus mugo and Larix decidua could be identified as potential sensitive and susceptible hosts for B. xylophilus isolates from Portugal, China and North America. Larix kaempferii was moderately susceptible and Pinus pinea was only susceptible against the isolate from Portugal. Single plants of the species Picea abies and Pinus halepensis contained a little number of B. xylophilus four weeks after inoculation but B. xylophilus could not be isolated from dead plants. Abies alba was no hosts for B. xylophilus. Migration and population dynamics of PWN was studied on Pinus sylvestris saplings. Plants were divided into 17 segments and nematodes were extracted from each segment at nine sampling dates within a 27 day period after inoculation. The nematode population density per sapling reached three population peaks, 12, 19 and 27 days after inoculation. PWN could be isolated from all 17 segments six days after inoculation. Results indicate that B. xylophilus first migrate rapidly throughout the host before building up a high population level. Nematodes were found to develop several overlapping populations in time depending on the area of the sapling. Four consecutive stages of nematode invasion were observed: (1) Early migration, (2) Distribution and colonisation of all plant parts, (3) Population build up and (4) Retreat into the rootsystem. The effect of temperature on population dynamics of PWN and pathogenicity towards Pinus sylvestris, Larix decidua and Picea abies was studied by inoculation of sapling with 4800 nematodes. Experiments were carried out in climate chambers at 15°C, 20°C and 25°C. Nematodes were extracted from shoots and roots at seven sampling dates during a 61 day period. Temperature had a major effect on the population dynamics of B. xylophilus in both susceptible conifer species. Temperature had no influence on the pathogenicity of PWN at 20 °C and 25 °C, as maximum mortality in Pinus sylvestris and Larix decidua was reached when temperature exceeded 20°C. However no wilt symptoms were detected at 15°C in any conifer species. The population in Pinus sylvestris increased to approximately 4000 nematodes per gram dry matter in shoots at 25°C. At 20°C the maximum population density in shoots was approximately 2500 nematodes per gram dry matter. A threshold population density of B. xylophilus must be reached for induction of irreversible wilt in Pinus sylvestris
Afternoon Shower: Jackson Wyoming; Old 22; February Night; Walnuttown, Pennsylvania; Elm Street: Late Afternoon; Hex Highway; Bridge; Gifts
Matthew Daub\u27s watercolor paintings and drawings have been exhibited throughout the U.S. in more than 20 solo exhibitions, and group shows at institutions including the Metropolitan Museum of Art, and the American Academy of Arts and Letters. He is a Professor of Fine Arts at Kutztown University of Pennsylvania
New interstitially stabilized cluster complexes of dysprosium, holmium and erbium
This thesis was intended to broaden our knowledge of interstitially stabilized rare-earth cluster halides of the elements dysprosium, holmium and erbium in terms of structures and electronic situation. Especially, new compounds of the M{ZM6}I12 type could be obtained for M = Ho and Z = Fe, Co, Ni, Ir and Pt. The structure consists of monomeric {ZM6} clusters surrounded by iodide ligands and additional MI6 entities interconnecting the clusters. For dysprosium, however, it was not possible to synthesize analogous cluster complexes with transition metals as interstitials, but with the C2 unit instead. Further investigations led to a phase of the composition Dy{CoDy4.53Y1.47}I12 with dysprosium and yttrium atoms both forming octahedral {M6} clusters and incorporating the transition metal cobalt. Apart from monomeric clusters, attention was focused on condensed cluster phases: The condensation of a cluster edge resulted in the formation of bi-octahedral units in {(C2)2M10}X18 with M = Dy, X = Br and M = Er, X = I, encapsulating a C2 dumbbell. Further condensation led to the tetrameric clusters {Ru4Ho16}I28{Ho4} and {(C2)2O2Dy14}I24 with the former consisting of {Ru4Ho16}I36 units comprising a tetrahedral arrangement of ruthenium interstitials and furthermore exhibiting empty {Ho4}I8 tetrahedra resembling PrI2-V. {(C2)2O2Dy14}I24 consists of a linearly ordered double tetrahedra encapsulating oxygen atoms and flanked by octahedra containing C2 dumbbells. The cluster complexes {(C2)ODy6}I9, {IrHo3}I3 and {(C2)Er4}I6 represent cluster chains. {(C2)ODy6}I9 consists of the same motif as {(C2)2O2Dy14}I24, just being condensed via common octahedral edges. {IrHo3}I3 contains monocapped trigonal prismatic {IrHo7} clusters that are arranged in zig-zag chains. In {(C2)Er4}I6, trans-edge connected {(C2)Er6} octahedra are alternately elongated and compressed depending on the orientation of the interstitial C2 unit. Band structure calculations reveal that Z-M interactions are the driving force for cluster formation and M-M interactions just play a minor role in terms of bonding
A Study of Gamma Radiation Induced Carbon Steel Corrosion
This thesis presents work on the development of a mechanistic understanding of the effect of ionizing radiation on the aqueous corrosion kinetics of carbon steel. Exposed to ionizing radiation, water decomposes into a range of oxidizing (O2, âąOH, HO2âą, H2O2) to reducing (âąeaqâ, âąO2â, âąH) species. The production of the redox active species by radiolysis can have a significant effect on the corrosion behaviour of a metal. Of particular interest is the effect of radiolysis on corrosion when the solution environment, such as temperature, pH, and concentrations of chemical additives, changes over time. Since these solution parameters also affect the radiolysis behaviour, it was important to develop a clear understanding of separate effects of these parameters.
To achieve a better understanding, a number of electrochemical and surface analytical techniques were employed. The combination of electrochemical and surface analyses provided a picture of oxidation that largely resulted in the formation of a magnetite oxide layer, but the further oxidation, dissolution, and reactivity of the oxide was sensitive to all parameters studied. The production of water radiolysis products via gamma irradiation was seen to have a net oxidizing effect on the growing oxide film, increasing the oxide film resistance. At all temperatures studied, irradiation did not result in significant oxide structural changes or oxide film breakdown events
The Labors, Infrastructures and Plastics of Mumbai\u27s Waste Flows
This thesis attends to some of the diverse flows of various plastic post-discard in Mumbai, India. I examine the material and imagined geographies of plastic discard and collection; the labors through which these different kinds of plastics move; and the infrastructures, spaces and relations that shape the rhythms and subjectivities of waste discard and work. I think with these flows alongside concern for marine plastic pollution and within the context of rising seas in particular. I show, for example, how the existence of marine plastic is not just the result of intentional disposal into waterways because of infrastructural exclusions, but that the very practices of waste collection and disposal are not designed to accommodate unstable grounds and matter in assemblages that produce âfloodâ vulnerability. At the same time, these dynamic infrastructural ecologies of waste and water create expanding and shifting spaces for plastic collection. I also consider how efforts to circulate âlow-value plasticsâ which often enter the sea might shift the infrastructures and organization of waste collection and work. Together, this thesis hopes to raise questions of how different relations to water and of wasting might be considered in relation and obligation to the lives that plastic and waste helps sustain and with consideration to ongoing forms of vulnerability and inequality
- âŠ