554 research outputs found

    Work-related helping and family functioning: a work-home resources perspective

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    Using the work–home resources (W-HR) model as an overarching framework, our study seeks to examine the interplay between employees’ provision and receipt of interpersonal organizational citizenship behaviours (OCB-I; i.e. helping behaviours), and its spillover effects on two family outcomes (family performance and marital withdrawal behaviours). Further, we simultaneously test resource depletion (emotional exhaustion) and resource generation (personal accomplishment) mechanisms linking OCB-Is and the family domain. Based on a time-lagged, dual-source study of 320 employees, we found that OCB-I enactment is positively related to both exhaustion (only for those who receive low OCB-Is from colleagues) and personal accomplishment at work (regardless of OCB-I receipt), which interferes with and enriches employees’ family lives, respectively. We discuss the theoretical contributions of these findings to OCB research and the W-HR model

    History effect in inhomogeneous superconductors

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    A model was proposed to account for a new kind of history effect in the transport measurement of a sample with inhomogeneous flux pinning coupled with flux creep. The inhomogeneity of flux pinning was described in terms of alternating weak pinning (lower jc) and strong pinning region (higher jc). The flux creep was characterized by logarithmic barrier. Based on this model, we numerically observed the same clockwise V-I loops as reported in references. Moreover, we predicted behaviors of the V-I loop at different sweeping rates of applied current dI/dt or magnetic fields Ba, etc. Electric transport measurement was performed in Ag-sheathed Bi2-xPbxSr2Ca2Cu3Oy tapes immersed in liquid nitrogen with and without magnetic fields. V-I loop at certain dI/dt and Ba was observed. It is found that the area of the loop is more sensitive to dI/dt than to Ba, which is in agreement well with our numerical results.Comment: To appear in Phys Rev B, October 1 Issu

    2D Mathematical Modeling For Fluvial Processes Considering The Influence Of Vegetation And Bank Erosion

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    A 2D mathematical model for fluvial processes capable of considering the influence of vegetation and non-cohesive bank erosion is established based on a body-fitted coordinate system in this paper. The authors have improved a previously developed simulation model by taking into account the impact of vegetation with a vegetation stress term in the momentum conservation equation. A simple simulation method is adopted in the bank erosion model. Simulation runs were performed for a conceptual alluvial channel, the results of channel plan-form and cross section changes suggest that the 2D model predictions agree acceptable with the classic theories of channel pattern formation considering the effect of vegetation

    Interference-induced gain in Autler-Townes doublet of a V-type atom in a cavity

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    We study the Autler-Townes spectrum of a V-type atom coupled to a single-mode, frequency-tunable cavity field at finite termperature, with a pre-selected polarization in the bad cavity limit, and show that, when the mean number of thermal photons N≫1N\gg 1 and the excited sublevel splitting is very large (the same order as the cavity linewidth), the probe gain may occur at either sideband of the doublet, depending on the cavity frequency, due to the cavity-induced interference.Comment: Minor changes are mad

    Cavity implementation of quantum interference in a Λ\Lambda-type atom

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    A scheme for engineering quantum interference in a Λ\Lambda-type atom coupled to a frequency-tunable, single-mode cavity field with a pre-selected polarization at finite temperature is proposed. Interference-assisted population trapping, population inversions and probe gain at one sideband of the Autler-Townes spectrum are predicted for certain cavity resonant frequencies.Comment: 2 postscript figures are adde

    Exciton swapping in a twisted graphene bilayer as a solid-state realization of a two-brane model

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    It is shown that exciton swapping between two graphene sheets may occur under specific conditions. A magnetically tunable optical filter is described to demonstrate this new effect. Mathematically, it is shown that two turbostratic graphene layers can be described as a "noncommutative" two-sheeted (2+1)-spacetime thanks to a formalism previously introduced for the study of braneworlds in high energy physics. The Hamiltonian of the model contains a coupling term connecting the two layers which is similar to the coupling existing between two braneworlds at a quantum level. In the present case, this term is related to a K-K' intervalley coupling. In addition, the experimental observation of this effect could be a way to assess the relevance of some theoretical concepts of the braneworld hypothesis.Comment: 15 pages, 3 figures, final version published in European Physical Journal

    Using rootstocks to lower berry potassium concentrations in 'Cabernet Sauvignon' grapevines

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    Potassium is the most abundant cation in grape berries. It has important roles in grapevine physiology and winemaking. This study investigates the feasibility of using rootstocks to lower berry potassium concentrations ([K]) in 'Cabernet Sauvignon' grapevines. The ultimate target is to achieve lower pH and higher titratable acidity (TA) in grape juice so as to bring down the cost of acid adjustment during winemaking. The specific objective here is to provide new insights into the potential of particular rootstocks to modify K uptake by 'Cabernet Sauvignon' grapevines and their partitioning and accumulation into grape berries. The vineyard soils of a replicated rootstock trial located in the Limestone Coast of South Australia were characterised. Petiole, berry and juice nutrient content were assessed at oenological maturity of 'Cabernet Sauvignon' grown on eight different rootstocks. Rootstock had an impact on cations of the vegetative tissue of 'Cabernet Sauvignon', with Merbein 5512 having the lowest petiole [K]. The concentrations of major cations in the berry were, however, not altered by rootstock. While no particular rootstock stood out in limiting 'Cabernet Sauvignon' berry K accumulation, berries grown on the 'Börner' rootstock tended to have slightly lower concentrations (< 10 %) relative to vines on their own roots. Across the rootstocks, juice pH tended to increase with greater juice [K], while juice TA tended to decrease with greater juice [K]. It was found that juice TA was higher for the rootstocks 140 Ruggeri and 110 Richter, and juice pH tended to be lower for the rootstocks 110 Richter, 140 Ruggeri, Merbein 5512 and Merbein 5489. There was no effect of rootstock on total soluble solids.Zeyu Xiao, K. A. DeGaris, T. Baby, S. J. McLoughlin, B. P. Holzapfel, R. R. Walker, L. M. Schmidtke, and S. Y. Rogier

    Vascular connections into the grape berry: the link of structural investment to seededness

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    Vascular bundles in the grape pedicel and berry contain the conduits, phloem and xylem, for transport of water, sugar, nutrients and signals into and through the grape berry and play a critical role in berry growth and composition. Here, we assess the vascular anatomy within the proximal region of the berry. Guided using a 3D berry model generated by micro-CT, differential staining of transverse sections of berries and receptacles was followed by fluorescent microscopy. Morphometric and vascular characteristics were analyzed within the central proximal region (brush zone, a fibrous extension from the pedicel vascular system into the berry) of the seeded cultivars Shiraz and Sauvignon Blanc, as well as the stenospermocarpic cultivars Ruby Seedless and Flame Seedless. Observations revealed a change in vascular arrangement from the receptacle into the berry brush zone and differences in xylem element size as well as xylem and phloem area relationships. Xylem anatomical and derived hydraulic parameters, as well as total tissue area of xylem and phloem varied between cultivars and in receptacle and berry components. Variation in vascular growth between grape pedicels and berries was independent of seededness. Differences in receptacle xylem vessel size and distribution could contribute to cultivar-dependent xylem backflow constraint.Zeyu Xiao, Sabrina Chin, Rosemary G. White, Aude M. Gourieroux, Vinay Pagay, Stephen D. Tyerman, Leigh M. Schmidtke and Suzy Y. Rogier

    3D visualisation of voids in grapevine flowers and berries using X‐ray micro computed tomography

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    First published: 06 January 2021Background and Aim: X-ray micro computed tomography (micro-CT) is a non-destructive 3D imaging technique that has been applied to plant morphology and anatomical studies to gain a better understanding of physiological phenomena in vivo. It is particularly useful for imaging voids in undisturbed fragile tissues and therefore may be applied to the delicate flowers and soft berries of Vitis vinifera. The characterisation of gas spaces and channels can offer insights into the process of tissue aeration and this may have implications on cell function and vitality. We assessed the use of micro-CT to visualise voids within these reproductive organs. Methods and Results: The internal structures of flowers and berries were captured through rapid micro-CT scanning and subsequently were recreated in 3D using image processing. The relative positions of the developing flower parts encased within the flower cap were visualised. Low density/porous tissue was identified within the pedicel and receptacle, con- necting the lenticels with the interior of the berry. Voids were present in the proximal mesocarp of mature berries forming a ‘detachment zone’ in both seeded and seedless cultivars. Voids permeated the mesocarp of mature seedless grape cultivars, but not seeded grapes. Conclusion: Micro-CT offers new insights regarding the distribution of voids on the morphology and compositional hetero- geneity of organs that are difficult to dissect and/or view with light microscopy. Significance of the Study: A better understanding of the physiology and functionality of grapevine reproductive tissues may be achieved by 3D visualisation of internal structure in vivo.Z. Xiao, T. Stait-Gardner, S.A. Willis, W.S. Price, F.J. Moroni, V. Pagay 
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    Direct Signals for Large Extra Dimensions in the Production of Fermion Pairs at Linear Colliders

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    We analyze the potentiality of the new generation of e+e−e^+e^- linear colliders to search for large extra dimensions via the production of fermion pairs in association with Kaluza-Klein gravitons (G), i.e. e+e−←ffˉGe^+e^- \leftarrow f\bar{f}G. This process leads to a final state exhibiting a significant amount of missing energy in addition to acoplanar lepton or jet pairs. We study in detail this reaction using full tree level contibutions due to the graviton emission and the standard model backgrounds. After choosing the cuts to enhance the signal, we show that a linear collider with a center-of-mass energy of 500 GeV will be able to probe quantum gravity scales from 0.96(0.86) up to 4.1(3.3) TeV at 2(5)σ\sigma level, depending on the number of extra dimensions.Comment: 19 pages, 5 figures. Using RevTex, axodraw.sty. Discussion was extended. No changes in the results. Accepted for publication by Phys. Rev.
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