分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Platforms for all-optical computing possess photonic circuits made of silicon-based channels, metal wires or optical fibers, etc. However, such solid waveguides suffer from the lack of reversibility and reconfigurability if facing the next generation of light-guiding-light (LGL) computing scheme, which envisions circuitry-free and rapidly reconfigurable systems powered by dynamic interactions between light beams. Here, we proposed the ubiquitous air as a restorable LGL signal manipulation medium with transient air-plasma waveguide circuits. Briefly, by focusing femtosecond laser beams in the free space, the created atmospherical plasma filament array via photoionization was able to guide terahertz (THz) pulses along its epsilon-near-zero (ENZ) zone with a 1/f-profile spectral response. Consequently, this achieved a time-domain integration of the THz pulse in broad bandwidth. When the pumping laser was sequentially turned off and on, this multi-filament air-plasma structure was erased and rebuilt within nano- and femto-seconds, respectively, allowing rapid and repeated rearrangements of the all-optical stage. Furthermore, this air-based LGL information processing approach is promising to pave the way towards all-optical calculations during free-space directional transmission of THz waves, by which means the delivered THz signal can be remotely controlled.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The interacting dark energy (IDE) model is a promising alternative cosmological model which has the potential to solve the fine-tuning and coincidence problems by considering the interaction between dark matter and dark energy. Previous studies have shown that the energy exchange between the dark sectors in this model can significantly affect the dark matter halo properties. In this study, utilising a large set of cosmological $N$-body simulations, we analyse the redshift evolution of the halo concentration - mass ($c$ - $M$) relation in the IDE model, and show that the $c$ - $M$ relation is a sensitive proxy of the interaction strength parameter $\xi_2$, especially at lower redshifts. Furthermore, we construct parametrized formulae to quantify the dependence of the $c$ - $M$ relation on $\xi_2$ at redshifts ranging from $z=0$ to $0.6$. Our parametrized formulae provide a useful tool in constraining $\xi_2$ with the observational $c$ - $M$ relation. As a first attempt, we use the data from X-ray, gravitational lensing, and galaxy rotational curve observations and obtain a tight constraint on $\xi_2$, i.e. $\xi_2 = 0.071 \pm 0.034$. Our work demonstrates that the halo $c$ - $M$ relation, which reflects the halo assembly history, is a powerful probe to constrain the IDE model.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The interacting dark energy (IDE) model is a promising alternative cosmological model which has the potential to solve the fine-tuning and coincidence problems by considering the interaction between dark matter and dark energy. Previous studies have shown that the energy exchange between the dark sectors in this model can significantly affect the dark matter halo properties. In this study, utilising a large set of cosmological $N$-body simulations, we analyse the redshift evolution of the halo concentration - mass ($c$ - $M$) relation in the IDE model, and show that the $c$ - $M$ relation is a sensitive proxy of the interaction strength parameter $\xi_2$, especially at lower redshifts. Furthermore, we construct parametrized formulae to quantify the dependence of the $c$ - $M$ relation on $\xi_2$ at redshifts ranging from $z=0$ to $0.6$. Our parametrized formulae provide a useful tool in constraining $\xi_2$ with the observational $c$ - $M$ relation. As a first attempt, we use the data from X-ray, gravitational lensing, and galaxy rotational curve observations and obtain a tight constraint on $\xi_2$, i.e. $\xi_2 = 0.071 \pm 0.034$. Our work demonstrates that the halo $c$ - $M$ relation, which reflects the halo assembly history, is a powerful probe to constrain the IDE model.
分类： 生物学 >> 植物学 >> 植物生理学 提交时间： 2016-05-04
Hikaru Sato
Daisuke Todaka
Madoka Kudo
Junya Mizoi
Satoshi Kidokoro
Yu Zhao
Kazuo Shinozaki
Kazuko Yamaguchi-Shinozaki
摘要： The enhancement of heat stress tolerance in crops is an important challenge for food security to facilitate adaptation to global warming. In Arabidopsis thaliana, the transcriptional regulator DNA polymerase II subunit B3-1 (DPB3-1)/nuclear factor Y subunit C10 (NF-YC10) has been reported as a positive regulator of Dehydration-responsive element binding protein 2A (DREB2A), and the overexpression of DPB3-1 enhances heat stress tolerance without growth retardation. Here, we show that DPB3-1 interacts with DREB2A homologues in rice and soya bean. Transactivation analyses with Arabidopsis and rice mesophyll protoplasts indicate that DPB3-1 and its rice homologue OsDPB3-2 function as positive regulators of DREB2A homologues. Overexpression of DPB3-1 did not affect plant growth or yield in rice under nonstress conditions. Moreover, DPB3-1-overexpressing rice showed enhanced heat stress tolerance. Microarray analysis revealed that many heat stress-inducible genes were up-regulated in DPB3-1-overexpressing rice under heat stress conditions. However, the overexpression of DPB3-1 using a constitutive promoter had almost no effect on the expression of these genes under nonstress conditions. This may be because DPB3-1 is a coactivator and thus lacks inherent transcriptional activity. We conclude that DPB3-1, a coactivator that functions specifically under abiotic stress conditions, could be utilized to increase heat stress tolerance in crops without negative effects on vegetative and reproductive growth.
分类： 物理学 >> 核物理学 提交时间： 2024-01-04
摘要： Charge strippers play an essential role in heavy-ion accelerators by stripping the projectile ions to higher charge states to enhance the acceleration efficiency downstream of the stripper. In the high-energy mode of the booster ring (BRing) of the high-intensity heavy-ion accelerator facility, the pre-accelerated ions from the iLinac will be stripped by a carbon foil to higher charge states and then injected into the BRing. The key parameters of the stripper and stripped ions were calculated, and the influence of stripping on the beam quality was discussed. To get high stripping efficiencies, the foil thicknesses and resultant charge state distributions for the typical ions were determined by the code ETACHA. The equilibrium thickness was obtained for the U beam, while the stripper thicknesses for the Xe and Kr beams were determined based on a compromise between the stripped charge states and the stripping efficiency. The energy loss, energy straggling, and emittance growth due to stripping have a non-negligible impact on the transport of the stripped beams and the injection of the ring. Therefore, these parameters were simulated by GEANT4. In addition, the foils temperature evolution, which greatly affects the foil lifetime, was simulated by ANSYS. The maximum temperature of the foil bombarded by the U and Xe beams with the nominal parameters will exceed the safe value in terms of the impact of evaporation on the foils lifetime. Given the foil temperature constraint, the highest tolerable beam intensity and the injected ion number into the ring were derived for different beam sizes. The results of this paper will present important reference data for the optimization design and commissioning of the beamline and injection to the BRing for the stripped ions.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Li Tao
Zhiyong Li
Kun Chen
Yaoqiang Zhou
Hao Li
Ximiao Wang
Runze Zhan
Xiangyu Hou
Yu Zhao
Junling Xu
Teng Qiu
Xi Wan
Jian-Bin Xu
摘要： To develop highly sensitive, stable and repeatable surface-enhanced Raman scattering (SERS) substrates is crucial for analytical detection, which is a challenge for traditional metallic structures. Herein, by taking advantage of the high surface activity of 1T' transition metal telluride, we have fabricated high-density gold nanoparticles (AuNPs) that are spontaneously in-situ prepared on the 1T' MoTe2 atomic layers via a facile method, forming a plasmonic-2D material hybrid SERS substrate. This AuNP formation is unique to the 1T' phase, which is repressed in 2H MoTe2 with less surface activity. The hybrid structure generates coupling effects of electromagnetic and chemical enhancements, as well as excellent molecule adsorption, leading to the ultrasensitive (4*10^-17 M) and reproducible detection. Additionally, the immense fluorescence and photobleaching phenomena are mostly avoided. Flexible SERS tapes have been demonstrated in practical applications. Our approach facilitates the ultrasensitive SERS detection by a facile method, as well as the better mechanistic understanding of SERS beyond plasmonic effects.
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