3,361 research outputs found

    Laser field strength dependence of solid high-harmonic generation from doped systems

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    We have theoretically studied the field-strength dependent high-harmonic generation (HHG) in doped systems like nano-size or bulk materials. Our results show when the amplitude of the vector potential A_peak of the driving laser reaches the half-width of the Brillouin zone ({\pi}/a0), the harmonic yield of the undoped systems is larger than the doped systems. The band-climbing process enhances the interband transition of HHG for higher conduction bands. When A_peak is below {\pi}/a0 , the harmonic yield of the doped systems is stronger than the undoped systems. The atomic doping density also influences the field-strength dependent spectra.Comment: 10 page

    Long-term inhibition of kindled seizures by brain stimulation

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    It was concluded from previous studies that prior stimulation produced a long-lasting inhibition of kindled seizures only when a series of convulsions were evoked. The present study describes a brain stimulation procedure capable of producing a long-lasting inhibition of kindled convulsions without evoking prior convulsions of EEG afterdischarge. Electrodes were implanted in the amygdala of rats, which were then kindled to a criterion of five successive tonic-clonic convulsions. After kindling, the animals were exposed to a regimen of intermittent amygdala stimulation, which was gradually increased in intensity in small incremental steps from a point just below the convulsion threshold to an intensity above the original kindling current. Using this procedure, it proved possible to administer high stimulation intensities without evoking any behavioral convulsions or EEG afterdischarges. Subsequent to this inhibitory procedure, amygdala stimulation did not evoke convulsions or EEG seizures for as long as 7 days. Additional studies tested the relative effectiveness of different stimulation rggimens and parameters for producing long-lasting inhibition of kindled seizures. The magnitude of the incremental intensity steps, the interstimulus interval, and the intensity of stimulation all proved to be relevent. We concluded that long-lasting inhibition of kindled seizures could be produced by prior stimulation that did not evoke seizures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24000/1/0000249.pd

    NETWORK DEVICE SYSTEM LOGGING SUMMARIZATION BASED ON LOW-RANK ADAPTATION AND CONTRASTIVE LEARNING

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    Techniques are presented herein that support the automatic generation of refined and summarized text from a system logging (syslog) message sequence. Aspects of the presented techniques employ an abstractive syslog summarization large language model (LLM) that is trained with contrastive learning and then fine-tuned using a Low-Rank Adaptation (LoRA) methodology. Under further aspects of the presented techniques, auxiliary text (such as network incident reports and application incident reports) is added to the prompt of the input of the LLM model to help the model generate a richer syslog summarization

    Improved oxidation resistance of high emissivity coatings on fibrous ceramic for reusable space systems

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    To develop high emissivity coatings on fibrous ceramic substrates with improved thermal resistance for reusable space systems, WSi2–MoSi2–Si–SiB6-borosilicate glass coatings were prepared on fibrous ZrO2 by slurry dipping and subsequent high temperature rapid sintering. A coating with 20 wt% WSi2 and 50 wt% MoSi2 presents optimal thermal stability with only 10.06 mg/cm2 mass loss and 4.0% emissivity decrease in the wavelength regime 1.27–1.73 μm after 50 h oxidation at 1773 K. The advantages of double phase metal-silicide coatings combining WSi2 and MoSi2 include improved thermal compatibility with the substrate and an enhanced glass-mediated self-healing ability

    Retrieving rice (Oryza sativa L.) net photosynthetic rate from UAV multispectral images based on machine learning methods

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    Photosynthesis is the key physiological activity in the process of crop growth and plays an irreplaceable role in carbon assimilation and yield formation. This study extracted rice (Oryza sativa L.) canopy reflectance based on the UAV multispectral images and analyzed the correlation between 25 vegetation indices (VIs), three textural indices (TIs), and net photosynthetic rate (Pn) at different growth stages. Linear regression (LR), support vector regression (SVR), gradient boosting decision tree (GBDT), random forest (RF), and multilayer perceptron neural network (MLP) models were employed for Pn estimation, and the modeling accuracy was compared under the input condition of VIs, VIs combined with TIs, and fusion of VIs and TIs with plant height (PH) and SPAD. The results showed that VIs and TIs generally had the relatively best correlation with Pn at the jointing–booting stage and the number of VIs with significant correlation (p< 0.05) was the largest. Therefore, the employed models could achieve the highest overall accuracy [coefficient of determination (R2) of 0.383–0.938]. However, as the growth stage progressed, the correlation gradually weakened and resulted in accuracy decrease (R2 of 0.258–0.928 and 0.125–0.863 at the heading–flowering and ripening stages, respectively). Among the tested models, GBDT and RF models could attain the best performance based on only VIs input (with R2 ranging from 0.863 to 0.938 and from 0.815 to 0.872, respectively). Furthermore, the fusion input of VIs, TIs with PH, and SPAD could more effectively improve the model accuracy (R2 increased by 0.049–0.249, 0.063–0.470, and 0.113–0.471, respectively, for three growth stages) compared with the input combination of VIs and TIs (R2 increased by 0.015–0.090, 0.001–0.139, and 0.023–0.114). Therefore, the GBDT and RF model with fused input could be highly recommended for rice Pn estimation and the methods could also provide reference for Pn monitoring and further yield prediction at field scale
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