3,816 research outputs found
Root-knot nematode (Meloidogyne incognita) infection alters vegetative growth and nitrogen uptake and distribution in grapevine
Root-knot nematodes (RKN, Meloidogyne spp.) manipulate host cell developmental processes to build specialized feeding structure from which the larvae enlist nutrients. Nitrogen (N) is one of the most important components of plant metabolites, and isotopic tracers make it possible for us to study the transportation of the nitrogen metabolites in the whole plant. In order to figure out vegetative and physiological responses caused by RKN infection in vine, pot experiment was performed in this paper. The results showed that RKN infection weakened vine vigor with decreased biomass and increased root-shoot ratio. Whereas, before bursting the galls exhibited a higher metabolic activity, in comparison with control root, the root dehydrogenase activities improved 85 % and 71 % in the galls and adjacent roots respectively. In addition, RKN infection didn’t significantly alter nitrogen content and distribution in various tissues, which might be due to feeding pressure or duration. 15N Root labeling results indicated that RKN infection enhanced Nitrogen derived from fertilizer (Ndff) and nitrogen utilization efficiency of the annual root. It suggested that RKN temporarily turned grape root into nitrogen sinks to meet their demand. Finally, the infected plant retained relatively few storage nutrients in the root and shoot after defoliation
Radiative transfer modeling of phytoplankton fluorescence quenching processes
We report the first radiative transfer model that is able to simulate phytoplankton fluorescence with both photochemical and non-photochemical quenching included. The fluorescence source term in the inelastic radiative transfer equation is proportional to both the quantum yield and scalar irradiance at excitation wavelengths. The photochemical and nonphotochemical quenching processes change the quantum yield based on the photosynthetic active radiation. A sensitivity study was performed to demonstrate the dependence of the fluorescence signal on chlorophyll a concentration, aerosol optical depths and solar zenith angles. This work enables us to better model the phytoplankton fluorescence, which can be used in the design of new space-based sensors that can provide sufficient sensitivity to detect the phytoplankton fluorescence signal. It could also lead to more accurate remote sensing algorithms for the study of phytoplankton physiology
Contribution of Raman scattering to polarized radiation field in ocean waters
We have implemented Raman scattering in a vector radiative transfer model for coupled atmosphere and ocean systems. A sensitivity study shows that the Raman scattering contribution is greatest in clear waters and at longer wavelengths. The Raman scattering contribution may surpass the elastic scattering contribution by several orders of magnitude at depth. The degree of linear polarization in water is smaller when Raman scattering is included. The orientation of the polarization ellipse shows similar patterns for both elastic and inelastic scattering contributions. As polarimeters and multipolarization-state lidars are planned for future Earth observing missions, our model can serve as a valuable tool for the simulation and interpretation of these planned observations
Radiative Transfer Modeling of Phytoplankton Fluorescence Quenching Processes
We report the first radiative transfer model that is able to simulate phytoplankton fluorescence with both photo chemical and non-photo chemical quenching included. The fluorescence source term in the inelastic radiative transfer equation is proportional to both the quantum yield and scalar irradiance at excitation wavelengths. The photo chemical and non photo chemical quenching processes change the quantum yield based on the photosynthetic active radiation. A sensitivity study was performed to demonstrate the dependence of the fluorescence signal on chlorophyll a concentration, aerosol optical depths and solar zenith angles. This work enables us to better model the phytoplankton fluorescence, which can be used in the design of new space-based sensors that can provide sufficient sensitivity to detect the phytoplankton fluorescence signal. It could also lead to more accurate remote sensing algorithms for the study of phytoplankton physiology
Optimal maintenance strategy for systems with two failure modes
This paper considers a single-unit system subject to two types of failures: a traditional catastrophic failure and a two-stage delayed failure. Periodic inspections are carried out to identify the defective stage of the two-stage failure process, whereas preventive replacements are implemented to avoid any potential failure due to the catastrophic failure mode. We construct a basic maintenance model and then extend it to the cases of imperfect inspections (i.e., inspections that do not always notice a defective state). We analyze the renewal process of the system and establish the expected long-run cost rate (ELRCR). The optimal inspection period and preventive replacement interval are determined by minimizing the ELRCR. A case study on infusion pumps is presented to illustrate the proposed model
RAWIW: RAW Image Watermarking Robust to ISP Pipeline
Invisible image watermarking is essential for image copyright protection.
Compared to RGB images, RAW format images use a higher dynamic range to capture
the radiometric characteristics of the camera sensor, providing greater
flexibility in post-processing and retouching. Similar to the master recording
in the music industry, RAW images are considered the original format for
distribution and image production, thus requiring copyright protection.
Existing watermarking methods typically target RGB images, leaving a gap for
RAW images. To address this issue, we propose the first deep learning-based RAW
Image Watermarking (RAWIW) framework for copyright protection. Unlike RGB image
watermarking, our method achieves cross-domain copyright protection. We
directly embed copyright information into RAW images, which can be later
extracted from the corresponding RGB images generated by different
post-processing methods. To achieve end-to-end training of the framework, we
integrate a neural network that simulates the ISP pipeline to handle the
RAW-to-RGB conversion process. To further validate the generalization of our
framework to traditional ISP pipelines and its robustness to transmission
distortion, we adopt a distortion network. This network simulates various types
of noises introduced during the traditional ISP pipeline and transmission.
Furthermore, we employ a three-stage training strategy to strike a balance
between robustness and concealment of watermarking. Our extensive experiments
demonstrate that RAWIW successfully achieves cross-domain copyright protection
for RAW images while maintaining their visual quality and robustness to ISP
pipeline distortions
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