分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： We propose a method of complex-amplitude Fourier single-pixel imaging (CFSI) with coherent structured illumination to acquire both the amplitude and phase of an object. In the proposed method, an object is illustrated by a series of coherent structured light fields which are generated by a phase-only spatial light modulator, the complex Fourier spectrum of the object can be acquired sequentially by a single-pixel photodetector. Then the desired complex-amplitude image can be retrieved directly by applying an inverse Fourier transform. We experimentally implemented this CFSI with several different types of objects. The experimental results show that the proposed method provides a promising complex-amplitude imaging approach with high quality and a stable configuration. Thus, it might find broad applications in optical metrology and biomedical science.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： We propose and experimentally demonstrate a high-efficiency single-pixel imaging (SPI) scheme by integrating time-correlated single-photon counting (TCSPC) with time-division multiplexing to acquire full-color images at extremely low light level. This SPI scheme uses a digital micromirror device to modulate a sequence of laser pulses with preset delays to achieve three-color structured illumination, then employs a photomultiplier tube into the TCSPC module to achieve photon-counting detection. By exploiting the time-resolved capabilities of TCSPC, we demodulate the spectrum-image-encoded signals, and then reconstruct high-quality full-color images in a single-round of measurement. Based on this scheme, the strategies such as single-step measurement, high-speed projection, and undersampling can further improve the imaging efficiency.
分类： 药物科学 >> 结构生物学 提交时间： 2024-04-27
Heng Zhang
Yuling Yin
Tianwei Zhang
Canrong Wu
Wen Hu
Xinheng He
Benxun Pan
Sanshan Jin
Qingning Yuan
H. Eric Xu
Yi Jiang
摘要： The norepinephrine transporter (NET) plays a pivotal role in regulating neurotransmitter balance and is critical for normal physiology and neurobiology. Dysfunction of NET has been implicated in numerous neuropsychiatric diseases including depression, anxiety, attention deficit hyperactivity disorder, and Parkinson’s disease. Here we report cryo-EM structures of NET in apo and substrate-bound forms, as well as complexes with six antidepressants. The structures reveal an unexpected NET dimer interface predominantly mediated by cholesterol and lipid molecules. The substrate norepinephrine is found to bind deep within the central binding pocket, with its amine group interacting with a conserved aspartate. The structures also provide insight into antidepressant recognition, including how subtle differences in binding poses confer selectivity over other monoamine transporters. Together these breakthrough findings significantly advance our understanding of NET regulation and inhibition, providing templates for designing improved antidepressants to treat neuropsychiatric disorders.
分类： 物理学 >> 核物理学 提交时间： 2024-03-09
Xin-Tong Du
Xiao-Bao Wei
Shao-Bo Ma
Li-Na Sheng
Xue-Heng Zhang
Shi-Tao Wang
Kai-Long Wang
Chun-Wang Ma
Hool-Jin Ong
Zhi-Yu Sun
Shu-Wen Tang
Yu-Hong Yu
摘要： The study of nuclide production and its properties in the N=126 neutron-rich region is the frontier and hot topic in nuclear physics and astrophysics research. The upcoming High energy FRagment Separator (HFRS) at the High Intensity heavy-ion Accelerator Facility (HIAF), an in-flight separator at relativistic energies, is characterized by high beam intensity, large ion-optical acceptance, high magnetic rigidity, and high momentum resolution power. It provides an opportunity for the study of the production and properties of neutron-rich nuclei around N=126. In this paper, an experimental scheme is proposed to produce the neutron-rich nuclei around N=126 and simultaneously measure their mass and lifetime based on the HFRS separator, and the feasibility of this scheme is evaluated by the simulations. The results show that under the high resolution optical mode many new neutron-rich nuclei approaching the r-process abundance peak around A=195 can be produced for the first time, and many nuclei with unknown mass and lifetime can be produced with high statistics. Using the time-of-flight corrected by the measured dispersive position and the energy loss information, the cocktails produced from the 208Pb fragmentation can be unambiguously identified. Moreover, the masses of some neutron-rich nuclei in the vicinity of N=126 can be measured with high precision using the time-of-flight magnetic rigidity technique. This indicates that the HIAF-HFRS facility has potential for the production and property research of neutron-rich nuclei around N=126, which is of great significance for expanding chart of nuclides, developing nuclear theories, and understanding the origin of heavy elements in the universe.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Run Wen
FangXia An
Xian Zhong Zheng
Dong Dong Shi
Jianbo Qin
Valentino Gonzalez
Fuyan Bian
Haiguang Xu
Zhizheng Pan
Qing-Hua Tan
Wenhao Liu
Min Fang
Jian Ren
Yu Heng Zhang
Man Qiao
Shuang Liu
摘要： We present an analysis of physical properties of 34 [O III] emission-line galaxies (ELGs) at z=3.254$\pm$0.029 in the Extended Chandra Deep Field South (ECDFS). These ELGs are selected from deep narrow H2S(1) and broad Ks imaging of 383 arcmin$^{2}$ obtained with CFHT/WIRCam. We construct spectral energy distributions (SEDs) from U to Ks to derive the physical properties of ELGs. These [O III] ELGs are identified as starburst galaxies with strong [O III] lines of L([O III]) ~ 10$^{42.6}$ - 10$^{44.2}$ erg s$^{-1}$, and have stellar masses of M* ~ 10$^{9.0}$-10$^{10.6}$ M$_\odot$ and star formation rates of ~ 10-210 M$_\odot$ yr$^{-1}$. Our results show that 24% of our sample galaxies are dusty with Av > 1 mag and EW(OIII)$_{rest}$ ~ 70-500 $\AA$, which are often missed in optically selected [O III] ELG samples. Their rest-frame UV and optical morphologies from HST/ACS and HST/WFC3 deep imaging reveal that these [O III] ELGs are mostly multiple-component systems (likely mergers) or compact. And 20% of them are nearly invisible in the rest-frame UV owing to heavy dust attenuation. Interestingly, we find that our samples reside in an overdensity consisting of two components: one southeast (SE) with an overdensity factor of $\delta_{gal}$ ~ 41 over a volume of 13$^{3}$ cMpc$^{3}$ and the other northwest (NW) with $\delta_{gal}$ ~ 38 over a volume of 10$^{3}$ cMpc$^{3}$. The two overdense substructures are expected to be virialized at z=0 with a total mass of ~ 1.1 x 10$^{15}$ M$_\odot$ and ~ 4.8 x 10$^{14}$ M$_\odot$, and probably merge into a Coma-like galaxy cluster.
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