169,510 research outputs found
Periodic Behavior of the Minimal Colijn-Plazzotta Rank for Trees with a Fixed Number of Leaves
No full textThe Colijn-Plazzotta ranking is a certain bijection between the unlabeled binary rooted trees and the positive integers, such that the integer associated with a tree is determined from the integers associated with the two immediate subtrees of its root. Letting a_n denote the minimal Colijn-Plazzotta rank among all trees with a specified number of leaves n, the sequence {a_n} begins 1, 2, 3, 4, 6, 7, 10, 11, 20, 22, 28, 29, 53, 56, 66, 67 (OEIS A354970). Here we show that a_n ∼ 2 [2^{P(log₂ n)}]ⁿ, where P varies as a periodic function dependent on {log₂ n} and satisfies 1.24602 < 2^{P(log₂ n)} < 1.33429
Pushing the Limits: A Search for the Lepton Flavour Violating Decay τ → 3μ within Heavy Flavour Jets with the Atlas Detector
No full textContains fulltext :
214940.pdf (Publisher’s version ) (Open Access)Radboud University, 05 maart 2020Promotores : Groot, N. de, Colijn, A.P.149 p
Factors Influencing Phytophthora ramorum Infectivity on Umbellularia californica and Testing of a Defoliation-Based Control Method
No full textThe primary foliar host for Phytophthora ramorum is Umbellularia californica (bay laurel), a tree species that serves as a reservoir for infections in California woodlands. I investigated environmental and pathogen-mediated influences on the incidence and severity of P. ramorum infection of U. californica as well as developing non-destructive means for controlling P. ramorum in woodlands.\ud
The distribution and abundance of P. ramorum in California is typically assessed by counting symptomatic hosts and confirmed by culturing the pathogen from field-collected samples. I hypothesized that the probability of a successful culture depends on the local environmental conditions where the field samples are collected. In 2010, an extensive culturing study was conducted within a previously established plot network in Sonoma County, where P. ramorum has been studied since 2003. I collected symptomatic leaf tissue for 424 trees in 153 plots randomly distributed within a 275 sq km region. Phytophothora ramorum was successfully cultured from 138 trees (32.5%) and collected from 71 plots (46.4%). Culture success was greatest in the southwest portion of the study area and lowest in the northeast. Culture success was positively related to topographic moisture index and field count of symptomatic leaves at the site and negatively related to average mean temperature at the site. These data show that culture success in the laboratory could be used as an indicator of inoculum load in the field. Studies that rely solely on culture success to determine pathogen presence should use caution in interpreting results, as they may overlook the possibility of false negatives.\ud
Additionally, I developed a live plant model to assess the validity of the commonly used detached leaf method for predicting interactions that occur between\ud
P. ramorum and foliar hosts. Specifically, I assessed infectivity of detached leaves and attached leaves from the same U. californica trees in a growth chamber and compared this to infectivity of detached leaves in an incubator. After seven days, lesions were scored. Mean infection score did not differ between detached leaves and attached leaves in the growth chamber. Detached leaves in the growth chamber and detached leaves in the incubator also did not differ significantly. Despite differences in light and humidity between the growth chamber and the incubator, no differences in infection score were found between any of the treatments. These results suggest that the detached leaf assay is a good indicator of infectivity in live trees.\ud
Finally, I examined controlled defoliation as an alternative to the current practice of managing P. ramorum through the destruction and removal of U. californica trees near symptomatic plants. Twenty-four U. californica seedlings were placed in six exclosures under infected canopies in Fairfield Osborn Preserve in February 2011. Two trees in each exclosure were sprayed in May and July 2011 with Ethephon, which releases ethylene upon decomposition, thereby inducing leaf abscission. Lesions were counted post treatment in January 2012. Leaves on the trees that received treatment developed significantly fewer lesions compared to the control group. Control saplings had 3.5 fold more infections than defoliated saplings. Defoliated saplings did experience excess lateral shooting, a side effect of Ethephon, as well as a dead zone at the crown. Further testing could determine the long-term effects of Ethephon on U. californica saplings and whether this dead zone is permanent or temporary. Ethephon does show promise as an alternate control method for P. ramorum.California Native Plant Societ
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dr. Edward P. Wimberly, ITC, July 2011
No full textThis video is a conversation with Dr. Edward P. Wimberly. Dr. Wimberly talks about his book, "No Shame in Wesley's Gospel: A Twenty-First Century Pastoral Gospel". Brad Ost, AUC Woodruff Library, is the interviewer
Universal Statistical Properties of Inertial-particle Trajectories in Three-dimensional, Homogeneous, Isotropic, Fluid Turbulence
No full textWe obtain new universal statistical properties of heavy-particle trajectories in three-dimensional, statistically steady, homogeneous, and isotropic turbulent flows by direct numerical simulations. We show that the probability distribution functions (PDFs) P(Φ), of the angle Φ between the Eulerian velocity u and the particle velocity v, at a point and time, scales as P(Φ) ∼Φ−, with a new universal exponent ≃ 4
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Genuine memoirs of the celebrated Miss Maria Brown [electronic resource] : Exhibiting the life of a courtezan, in the most fashionable scenes of dissipation. Published by the author of a W** of P*** In two volumes.
No full textAuthor of a W** of P*** [Woman of Pleasure] = John Cleland, to whom this work is sometimes attributed.Electronic reproduction.English Short Title Catalog,Reproduction of original from British Library
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