387 research outputs found

    Investigation of plant growth and transpiration-induced matric suction under mixed grass-tree conditions

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    Although evapotranspiration-induced matric suction for single species has been widely studied, little is known about how mixed-species planting would affect the plant growth and induced matric suction. This study aims to explore the effects of grass-tree interaction on their growth and induced matric suction during evapotranspiration (ET) and rainfalls. Field monitoring was carried out to measure matric suction responses in compacted soil that was vegetated with (i) single tree species, Schefflera heptaphylla and (ii) mixed species of the trees and a grass species, Cynodon dactylon. In each condition, three tree spacings (120, 180 and 240 mm) were planted. When tree spacing increased from 120 to 240 mm, the peak tree root area index (RAI, for fine roots with diameterThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

    Quivers, Tilings, Branes and Rhombi

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    We describe a simple algorithm that computes the recently discovered brane tilings for a given generic toric singular Calabi-Yau threefold. This therefore gives AdS/CFT dual quiver gauge theories for D3-branes probing the given non-compact manifold. The algorithm solves a longstanding problem by computing superpotentials for these theories directly from the toric diagram of the singularity. We study the parameter space of a-maximization; this study is made possible by identifying the R-charges of bifundamental fields as angles in the brane tiling. We also study Seiberg duality from a new perspective.Comment: 36 pages, 40 figures, JHEP

    Brane Tilings and Exceptional Collections

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    Both brane tilings and exceptional collections are useful tools for describing the low energy gauge theory on a stack of D3-branes probing a Calabi-Yau singularity. We provide a dictionary that translates between these two heretofore unconnected languages. Given a brane tiling, we compute an exceptional collection of line bundles associated to the base of the non-compact Calabi-Yau threefold. Given an exceptional collection, we derive the periodic quiver of the gauge theory which is the graph theoretic dual of the brane tiling. Our results give new insight to the construction of quiver theories and their relation to geometry.Comment: 46 pages, 37 figures, JHEP3; v2: reference added, figure 13 correcte

    Childhood Adversity, Resilience, and Mental Health: A Sequential Mixed-Methods Study of Chinese Young Adults

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    Resilience is a key health protective factor for those with adverse childhood experiences (ACEs), but little research has explored how it manifests in early adulthood or across cultures. The purpose of this study was to generate a fuller understanding of resilience and its contribution to the relationships between mental health problems and ACEs among Chinese young adults in Hong Kong. Using a sequential explanatory mixed-methods design, 433 Chinese young adults aged 18-24 years were surveyed online to examine the relationships between ACEs, resilience, and mental health problems (depression, anxiety, maladjustment, and post-traumatic stress symptoms). Among them, 34 participants with ACEs were purposively selected and interviewed to explore cultural factors that influenced their resilience. Quantitative data were analyzed using multiple hierarchical regression analyses; qualitative data were analyzed using a qualitative descriptive approach.Higher cumulative ACE exposure was associated with higher severity of adjustment disorder and odds for screening positive for post-traumatic stress disorders, but not for symptoms of depression or anxiety. Resilience significantly contributed to explaining variances across all mental health outcomes over and beyond ACEs and in a protective fashion. Four themes emerged from qualitative interviews: (1) Privacy, emotional restraint, and “saving face”; (2) Conforming to preserve harmony; (3) A will to excel; and (4) Viewing adversity as a matter of luck. These findings suggest Chinese young adults’ resilience was influenced by cultural norms of restraint, conformity, competition, and superstition. The present study provides a model for future studies using a mixed-methods design to deeply examine resilience among younger people exposed to early adversities within sociocultural, historical, or geographical contexts

    Effect of Collection Month, Visible Light, and Air Movement on the Attraction of Male Agriotes obscurus L. (Coleoptera: Elateridae) Click Beetles to Female Sex Pheromone

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    Elaterid female sex pheromone, while currently used for monitoring the adult life stage (click beetle), has only recently been explored as a potential management tool. Consequently, there is little understanding of how abiotic and biotic conditions influence the response of click beetles to the pheromone. We examined whether the response of male Agriotes obscurus L. (Coleoptera: Elateridae) beetles to a cellulose-based formulation of female sex pheromone (‘pheromone granules’) is influenced by air movement, presence of visible light, and month of beetle collection. In addition, we investigated the distance from which beetles were attracted to the pheromone granules. Click beetle response was determined by measuring movement parameters in free-walking arena experiments. The response to pheromone was not affected by the presence or absence of visible light. We found that beetles collected earlier in the season had increased activity and interaction with pheromone under moving air conditions, compared to beetles collected later. When controlling for storage time, we confirmed that individuals collected in May were less active than beetles collected in March and April. In the field, beetles were recaptured from up to 14 m away from a pheromone granule source, with over 50% being recovered within 4.4 h from a distance of 7 m or less. Understanding how abiotic and biotic factors affect pest response to pheromone can lead to more effective and novel uses of pheromone-based management strategies

    Pallet Management System: A Study of the Implementation of UID/RFID Technology for Tracking Shipping Materials within the Department of Defense Distribution Network

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    Sponsored Report (for Acquisition Research Program)The purpose of this MBA project is to identify the typical pallet utilization for the Defense Distribution Depot San Joaquin (DDJC) shipments to the Defense Distribution Depot San Diego (DDDC). That information will be used as the basis for suggesting a standardized reutilization management system for wood and non-wood pallets. This project will analyze the inclusion of Radio Frequency Identification and Unique Item Identification in conjunction with bar code technology for the improvement of asset visibility within the Department of Defense''s supply network.Naval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited

    Deformations of calibrated D-branes in flux generalized complex manifolds

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    We study massless deformations of generalized calibrated cycles, which describe, in the language of generalized complex geometry, supersymmetric D-branes in N=1 supersymmetric compactifications with fluxes. We find that the deformations are classified by the first cohomology group of a Lie algebroid canonically associated to the generalized calibrated cycle, seen as a generalized complex submanifold with respect to the integrable generalized complex structure of the bulk. We provide examples in the SU(3) structure case and in a `genuine' generalized complex structure case. We discuss cases of lifting of massless modes due to world-volume fluxes, background fluxes and a generalized complex structure that changes type.Comment: 52 pages, added references, added comment on ellipticity in appendix B, made minor changes according to instructions referee JHE

    A Precise Measurement of the Weak Mixing Angle in Neutrino-Nucleon Scattering

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    We report a precise measurement of the weak mixing angle from the ratio of neutral current to charged current inclusive cross-sections in deep-inelastic neutrino-nucleon scattering. The data were gathered at the CCFR neutrino detector in the Fermilab quadrupole-triplet neutrino beam, with neutrino energies up to 600 GeV. Using the on-shell definition, sin2ΞW≡1−MW2MZ2{\rm sin ^2\theta_W} \equiv 1 - \frac{{\rm M_W} ^2}{{\rm M_Z} ^2}, we obtain sin2ΞW=0.2218±0.0025(stat.)±0.0036(exp. syst.)±0.0040(model){\rm sin ^2\theta_W} = 0.2218 \pm 0.0025 ({\rm stat.}) \pm 0.0036 ({\rm exp.\: syst.}) \pm 0.0040 ({\rm model}).Comment: 10 pages, Nevis Preprint #1498 (Submitted to Phys. Rev. Lett.

    Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

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    This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio
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