11,835 research outputs found

    A note on the boundary contribution with bad deformation in gauge theory

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    Motivated by recently progresses in the study of BCFW recursion relation with nonzero boundary contributions for theories with scalars and fermions\cite{Bofeng}, in this short note we continue the study of boundary contributions of gauge theory with the bad deformation. Unlike cases with scalars or fermions, it is hard to use Feynman diagrams directly to obtain boundary contributions, thus we propose another method based on the N=4{\cal N}=4 SYM theory. Using this method, we are able to write down a useful on-shell recursion relation to calculate boundary contributions from related theories. Our result shows the cut-constructibility of gauge theory even with the bad deformation in some generalized sense.Comment: 16 pages, 7 figure

    Spatiotemporal Dynamics and Control of Strong Coupling in Plasmonic Nanocavities

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    © 2017 American Chemical Society. In the light-matter strong coupling regime, the excited state of quantum emitters is inextricably linked to a photonic mode, leading to hybrid states that are part light and part matter. Recently, there has been a huge effort to realize strong coupling with nanoplasmonics, since it provides a versatile environment to study and control molecules in ambient conditions. Among the most promising designs are plasmonic nanocavities that confine light to unprecedentedly small volumes. Such nanocavities, though, support multiple types of modes, with different field profiles and radiative decay rates (bright and dark modes). Here, we show theoretically that the different nature of these modes leads to mode beating within the nanocavity and the Rabi oscillations, which alters the spatiotemporal dynamics of the hybrid system. By specifically designing the illumination setup, we decompose and control the dark and bright plasmon mode excitation and therefore their coupling with quantum emitters. Hence, this work opens new routes for dynam ically dressing emitters, to tailor their hybrid states with external radiation

    Environmental drivers and the distribution of cold-water corals in the global ocean

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    Species distribution models (SDMs) are useful tools for describing and predicting the distribution of marine species in data-limited environments. Outputs from SDMs have been used to identify areas for spatial management, analyzing trawl closures, quantitatively measuring the risk of bottom trawling, and evaluating protected areas for improving conservation and management. Cold-water corals are globally distributed habitat-forming organisms that are vulnerable to anthropogenic impacts and climate change, but data deficiency remains an ongoing issue for the effective spatial management of these important ecosystem engineers. In this study, we constructed 11 environmental seabed variables at 500 m resolution based on the latest multi-depth global datasets and high-resolution bathymetry. An ensemble species distribution modeling method was used to predict the global habitat suitability for 10 widespread cold-water coral species, namely, 6 Scleractinian framework-forming species and 4 large gorgonian species. Temperature, depth, salinity, terrain ruggedness index, carbonate saturation state, and chlorophyll were the most important factors in determining the global distributions of these species. The Scleractinian Madrepora oculata showed the widest niche breadth, while most other species demonstrated somewhat limited niche breadth. The shallowest study species, Oculina varicosa, had the most distinctive niche of the group. The model outputs from this study represent the highest-resolution global predictions for these species to date and are valuable in aiding the management, conservation, and continued research into cold-water coral species

    Hierarchical Nanotexturing Enables Acoustofluidics on Slippery yet Sticky, Flexible Surfaces

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    The ability to actuate liquids remains a fundamental challenge in smart microsystems, such as those for soft robotics, where devices often need to conform to either natural or three-dimensional solid shapes, in various orientations. Here, we propose a hierarchical nanotexturing of piezoelectric films as active microfluidic actuators, exploiting a unique combination of both topographical and chemical properties on flexible surfaces, while also introducing design concepts of shear hydrophobicity and tensile hydrophilicity. In doing so, we create nanostructured surfaces that are, at the same time, both slippery (low in-plane pinning) and sticky (high normal-to-plane liquid adhesion). By enabling fluid transportation on such arbitrarily shaped surfaces, we demonstrate efficient fluid motions on inclined, vertical, inverted, or even flexible geometries in three dimensions. Such surfaces can also be deformed and then reformed into their original shapes, thereby paving the way for advanced microfluidic applications

    Concentrated vertical jetting mechanism for isotropically focused Zno/Si surface acoustic waves

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    This paper investigates vertical droplet jetting using circular surface acoustic wave (CSAW) devices with annular interdigitated transducers (AIDTs) fabricated on ZnO film coated silicon substrate. The surface vibration on the CSAW devices was simulated using finite element analysis and characterised using laser vibrometry. Results showed that focused wave patterns and compact nodal distributions of vibration were formed at the centre of ZnO/Si CSAW device, which is contrast to an anisotropic wave distribution patterns generated by the same pattern of AIDTs fabricated on 128° Y-cut LiNbO3. Simulation of liquid jetting induced by the isotropically focused CSAW was performed using coupled Volume of Fluid and Level-Set method. Results showed that a sharp and cylindrical liquid column was generated from the ZnO/Si CSAW device induced by acoustic energy coming from all directions within the plane due to the in-plane isotropic nature of the ZnO thin films. The simulation enabled us to capture the different streaming/jetting processes induced by the anisotropic distributions of acoustic pressure generated by the AIDTs on the 128° Y-cut LiNbO3 CSAW device. The concentrated vertical droplet jetting behaviour from the ZnO/Si CSAW devices was investigated experimentally and supported the simulated results

    Arabidopsis thaliana VDAC2 involvement in salt stress response pathway

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    Soil salinity seriously affects plants distribution and yield, while salt stress induces SOS genes, and voltage-dependent anion channels (VDAC) and a mitochondrial porin, are induced too. In this paper, phenotypes of AtVDAC2 transgenic lines and wild type (RLD) were analyzed. It was found that AtVDAC2 over-expressing transgenic plants were more sensitive to NaCl, and produced more H2O2 in the NaCl treatment. Also, to find the inner reason, the salt overly sensitive gene 3 (SOS3) expression level was changed with the expression of AtVDAC2. So, it was conjectured that the signal of salt stress response was first sent to AtVDAC2, then AtVDAC2 expression improved, leading to the down-stream signals changes, such as accumulation of H2O2 and improved expression of SOS3. So, it was found that in the over-expression of transgenic lines with AtVDAC2 up-regulation, SOS3 expression increased significantly, and in the inhibited-expressing lines, it was vice versa. In summary, AtVDAC2 was involved in salt stress signaling pathway, and it regulated SOS3 gene expression.Key words: Arabidopsis thaliana, voltage-dependent anion channels (VDAC), salt stress, signaling pathway

    Rising CO2 and warming reduce global canopy deman for nitrogen

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    Nitrogen (N) limitation has been considered as a constraint on terrestrial carbon uptake in response to rising CO2 and climate change. By extension, it has been suggested that declining carboxylation capacity (Vcmax) and leaf N content in enhanced-CO2 experiments and satellite records signify increasing N limitation of primary production. We predicted Vcmax using the coordination hypothesis, and estimated changes in leaf-level photosynthetic N for 1982–2016 assuming proportionality with leaf-level Vcmax at 25˚C. Whole-canopy photosynthetic N was derived using satellite-based leaf area index (LAI) data and an empirical extinction coefficient for Vcmax, and converted to annual N demand using estimated leaf turnover times. The predicted spatial pattern of Vcmax shares key features with an independent reconstruction from remotely-sensed leaf chlorophyll content. Predicted leaf photosynthetic N declined by 0.27 % yr-1, while observed leaf (total) N declined by 0.2–0.25 % yr-1. Predicted global canopy N (and N demand) declined from 1996 onwards, despite increasing LAI. Leaf-level responses to rising CO2, and to a lesser extent temperature, may have reduced the canopy requirement for N by more than rising LAI has increased it. This finding provides an alternative explanation for declining leaf N that does not depend on increasing N limitation

    Modeling, Oscillation Analysis and Distributed Stabilization Control of Autonomous PV-based Microgrids

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    Driven by rising energy demand and the goal of carbon neutrality, renewable energy generations (REGs), especially photovoltaic (PV) generations, are widely used in the urban power energy systems. While the intelligent control of microgrids (MG) brings economic and efficient operation, its potential stability problem cannot be ignored. To date, most of the research on modeling, analyzing and enhancing the stability of MG usually assume the DC-link as an ideal voltage source. However, this practice of ignoring the dynamics of DC-link may omit the latent oscillation phenomena of autonomous PV-based MG. First, this paper establishes a complete dynamic model of autonomous PV-based MG including PV panels and DC-link. Different from previous conclusions of idealizing DC-link dynamics, participation factor analysis finds the potential impact of DC-link dynamics on system dynamic performance, and different influence factors including critical control parameters and non-linear V-I output characteristic of PV array are considered to further reveal oscillation mechanisms. Second, based on the average consensus algorithm, a distributed stabilization controller with strong robustness is proposed to enhance stability of the PV-based MG, which does not affect the steady-state performance of the system. Finally, the correctness of all theoretical analysis and the effectiveness of the proposed controller are verified by time domain simulation and hardware-in-loop tests.10.13039/501100001809-National Natural Science Foundation of China (Grant Number: 51907031
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