2,844 research outputs found

    Evaluation of Broadcast Steam Application with Mustard Seed Meal in Fruiting Strawberry

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    Soil disinfestation with steam has potential to partially replace fumigants such as methyl bromide, chloropicrin, and 1,3-dichloropropene because it is effective, safer to apply, and has less negative impact on the environment. Here, we compared the efficacy of steam and steam + mustard seed meal (MSM) to chloropicrin on soil disinfection, plant growth, and fruit yield in a strawberry (Fragaria ×ananassa) fruiting field. The MSM was applied at 3368 kg·ha−1 before the steam application. Steam was injected into a 3-m-wide reverse tiller that was set to till 30 to 40 cm deep. Soil temperatures at depths of 10, 20, 25, and 35 cm were monitored. Steam and steam + MSM treatments reduced the viability of purslane seeds and nutsedge tubers, microsclerotia density of Verticillium dahliae, propagule density of Pythium ultimum, cumulative weed densities, and biomass compared with the nontreated control. Moreover, the steam application was as efficacious as chloropicrin on these pests. The growth and fruit yield of strawberries grown on soils previously treated with the steam and steam + MSM treatments were similar to those in the chloropicrin treatment and were higher than those in the nontreated control. Our study indicated that steam, steam + MSM, and chloropicrin are equally effective at suppressing weeds and soilborne pathogens. These results suggest that the steam and steam + MSM treatment can be a practical alternative for soil disinfestation in conventional and organic strawberry fields

    Soft gluon resummation for squark and gluino pair-production at hadron colliders

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    We report on the study of soft gluon effects in the production of squarks and gluinos at hadron colliders. Close to production threshold, the emission of soft gluon results in the appearence of large logarithmic corrections in the theoretical expressions. In order to resum these corrections at next-to-leading-logarithmic accuracy appropriate one-loop anomalous dimensions have to be calculated. We present the calculation of the anomalous dimensions for all production channels of squarks and gluinos and provide numerical predictions for the Tevatron and the LHC.Comment: 6 pages, talk given at RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology) October 25-30 2009, Ascona, Switzerlan

    Optimizing infrared to near infrared upconversion quantum yield of β-NaYF<sub>4</sub>:Er<sup>3+</sup> in fluoropolymer matrix for photovoltaic devices

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    The present study reports for the first time the optimization of the infrared (1523 nm) to near-infrared (980 nm) upconversion quantum yield (UC-QY) of hexagonal trivalent erbium doped sodium yttrium fluoride (β-NaYF4:Er3+) in a perfluorocyclobutane (PFCB) host matrix under monochromatic excitation. Maximum internal and external UC-QYs of 8.4% ± 0.8% and 6.5% ± 0.7%, respectively, have been achieved for 1523 nm excitation of 970 ± 43 Wm−2 for an optimum Er3+ concentration of 25 mol% and a phosphor concentration of 84.9 w/w% in the matrix. These results correspond to normalized internal and external efficiencies of 0.86 ± 0.12 cm2 W−1 and 0.67 ± 0.10 cm2 W−1, respectively. These are the highest values ever reported for β-NaYF4:Er3+ under monochromatic excitation. The special characteristics of both the UC phosphor β-NaYF4:Er3+ and the PFCB matrix give rise to this outstanding property. Detailed power and time dependent luminescence measurements reveal energy transfer upconversion as the dominant UC mechanism

    The current state of biomarker research for Friedreich's ataxia: a report from the 2018 FARA biomarker meeting

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    The 2018 FARA Biomarker Meeting highlighted the current state of development of biomarkers for Friedreich's ataxia. A mass spectroscopy assay to sensitively measure mature frataxin (reduction of which is the root cause of disease) is being developed. Biomarkers to monitor neurological disease progression include imaging, electrophysiological measures and measures of nerve function, which may be measured either in serum and/or through imaging-based technologies. Potential pharmacodynamic biomarkers include metabolic and protein biomarkers and markers of nerve damage. Cardiac imaging and serum biomarkers may reflect cardiac disease progression. Considerable progress has been made in the development of biomarkers for various contexts of use, but further work is needed in terms of larger longitudinal multisite studies, and identification of novel biomarkers for additional use cases

    Incorporating Statistical Strategy into Image Analysis to Estimate Effects of Steam and Allyl Isocyanate on Weed Control

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    Weeds are the major limitation to efficient crop production, and effective weed management is necessary to prevent yield losses due to crop-weed competition. Assessments of the relative efficacy of weed control treatments by traditional counting methods is labor intensive and expensive. More efficient methods are needed for weed control assessments. There is extensive literature on advanced techniques of image analysis for weed recognition, identification, classification, and leaf area, but there is limited information on statistical methods for hypothesis testing when data are obtained by image analysis (RGB decimal code). A traditional multiple comparison test, such as the Dunnett-Tukey-Kramer (DTK) test, is not an optimal statistical strategy for the image analysis because it does not fully utilize information contained in RGB decimal code. In this article, a bootstrap method and a Poisson model are considered to incorporate RGB decimal codes and pixels for comparing multiple treatments on weed control. These statistical methods can also estimate interpretable parameters such as the relative proportion of weed coverage and weed densities. The simulation studies showed that the bootstrap method and the Poisson model are more powerful than the DTK test for a fixed significance level. Using these statistical methods, three soil disinfestation treatments, steam, allyl-isothiocyanate (AITC), and control, were compared. Steam was found to be significantly more effective than AITC, a difference which could not be detected by the DTK test. Our study demonstrates that an appropriate statistical method can leverage statistical power even with a simple RGB index

    Algorithms and Bounds for Very Strong Rainbow Coloring

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    A well-studied coloring problem is to assign colors to the edges of a graph GG so that, for every pair of vertices, all edges of at least one shortest path between them receive different colors. The minimum number of colors necessary in such a coloring is the strong rainbow connection number (\src(G)) of the graph. When proving upper bounds on \src(G), it is natural to prove that a coloring exists where, for \emph{every} shortest path between every pair of vertices in the graph, all edges of the path receive different colors. Therefore, we introduce and formally define this more restricted edge coloring number, which we call \emph{very strong rainbow connection number} (\vsrc(G)). In this paper, we give upper bounds on \vsrc(G) for several graph classes, some of which are tight. These immediately imply new upper bounds on \src(G) for these classes, showing that the study of \vsrc(G) enables meaningful progress on bounding \src(G). Then we study the complexity of the problem to compute \vsrc(G), particularly for graphs of bounded treewidth, and show this is an interesting problem in its own right. We prove that \vsrc(G) can be computed in polynomial time on cactus graphs; in contrast, this question is still open for \src(G). We also observe that deciding whether \vsrc(G) = k is fixed-parameter tractable in kk and the treewidth of GG. Finally, on general graphs, we prove that there is no polynomial-time algorithm to decide whether \vsrc(G) \leq 3 nor to approximate \vsrc(G) within a factor n1−εn^{1-\varepsilon}, unless P==NP

    Antiferromagnetic magnons as highly squeezed Fock states underlying quantum correlations

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    Employing the concept of two-mode squeezed states from quantum optics, we demonstrate a revealing physical picture for the antiferromagnetic ground state and excitations. Superimposed on a N{\'e}el ordered configuration, a spin-flip restricted to one of the sublattices is called a sublattice-magnon. We show that an antiferromagnetic spin-up magnon is comprised by a quantum superposition of states with n+1n+1 spin-up and nn spin-down sublattice-magnons, and is thus an enormous excitation despite its unit net spin. Consequently, its large sublattice-spin can amplify its coupling to other excitations. Employing von Neumann entropy as a measure, we show that the antiferromagnetic eigenmodes manifest a high degree of entanglement between the two sublattices, thereby establishing antiferromagnets as reservoirs for strong quantum correlations. Based on these novel insights, we outline strategies for exploiting the strong quantum character of antiferromagetic (squeezed-)magnons and give an intuitive explanation for recent experimental and theoretical findings in antiferromagnetic magnon spintronics

    Routine monitoring and assessment of adults living with HIV: results of the British HIV Association (BHIVA) national audit 2015

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    BACKGROUND: The clinical care of people living with HIV changed fundamentally as a result of the development of effective antiretroviral therapy (ART). HIV infection is now a long-term treatable condition. We report a national audit to assess adherence to British HIV Association guidelines for the routine investigation and monitoring of adult HIV-1-infected individuals. METHODS: All UK sites known as providers of adult HIV outpatient services were invited to complete a case-note review and a brief survey of local clinic practices. Participating sites were asked to randomly select 50-100 adults, who attended for specialist HIV care during 2014 and/or 2015. Each site collected data electronically using a self-audit spreadsheet tool. This included demographic details (gender, ethnicity, HIV exposure, and age) and whether 22 standardised and pre-defined clinical audited outcomes had been recorded. RESULTS: Data were collected on 8258 adults from 123 sites, representing approximately 10% of people living with HIV reported in public health surveillance as attending UK HIV services. Sexual health screening was provided within 96.4% of HIV services, cervical cytology and influenza vaccination within 71.4% of HIV services. There was wide variation in resistance testing across sites. Only 44.9% of patients on ART had a documented 10-year CVD risk within the past three years and fracture risk had been assessed within the past three years for only 16.7% patients aged over 50 years. CONCLUSIONS: There was high participation in the national audit and good practice was identified in some areas. However improvements can be made in monitoring of cardiovascular risk, bone and sexual health

    Routine monitoring and assessment of adults living with HIV: results of the British HIV Association (BHIVA) national audit 2015.

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    BACKGROUND: The clinical care of people living with HIV changed fundamentally as a result of the development of effective antiretroviral therapy (ART). HIV infection is now a long-term treatable condition. We report a national audit to assess adherence to British HIV Association guidelines for the routine investigation and monitoring of adult HIV-1-infected individuals. METHODS: All UK sites known as providers of adult HIV outpatient services were invited to complete a case-note review and a brief survey of local clinic practices. Participating sites were asked to randomly select 50-100 adults, who attended for specialist HIV care during 2014 and/or 2015. Each site collected data electronically using a self-audit spreadsheet tool. This included demographic details (gender, ethnicity, HIV exposure, and age) and whether 22 standardised and pre-defined clinical audited outcomes had been recorded. RESULTS: Data were collected on 8258 adults from 123 sites, representing approximately 10% of people living with HIV reported in public health surveillance as attending UK HIV services. Sexual health screening was provided within 96.4% of HIV services, cervical cytology and influenza vaccination within 71.4% of HIV services. There was wide variation in resistance testing across sites. Only 44.9% of patients on ART had a documented 10-year CVD risk within the past three years and fracture risk had been assessed within the past three years for only 16.7% patients aged over 50 years. CONCLUSIONS: There was high participation in the national audit and good practice was identified in some areas. However improvements can be made in monitoring of cardiovascular risk, bone and sexual health
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