分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We download the LAMOST DR8 low resolution catalog 6,478,063 AFGK tpye stars and plot the figures of effective temperature, gravitational acceleration, and metal abundance. Some small and medium mass stars are evolved from pre-main sequence or main sequence stage to planetary nebula stage or white dwarf stage by the stellar evolution code \texttt{MESA}. We analyze the observed statistical data and model calculation results, and then obtain some basic conclusions preliminarily. Most red giant and asymptotic giant stars with log$g$ less than 0.85 have poor metal abundance. Most hot A type main-sequence stars are metal rich stars with log$g$ from 3.5 to 4.5. The conclusions are reasonable within a certain error range. The theory of a gap area in the H-R diagram for stellar evolutions of medium mass stars is reflected in the statistical figures. The central core hydrogen burning stage and the central core helium burning stage correspond to the peak structures in the gravitational acceleration statistical figures respectively. The metal abundances among A, F, G, and K type stars have a wide distribution. We can not simply replace the metal abundances of these stars with the metal abundance of the Sun when doing a fine research work.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Using the high resolution Milky Way-like model from Auriga simulation we study the chemical properties of the Galactic bulge, focusing on the metallicity difference between stars on the near side (in front of the Galactic center) and the far side (behind the Galactic center). In general, along certain sight lines the near side is more metal-rich than the far side, consistent with the negative vertical metallicity gradient of the disk, since the far side is located higher above the disk plane than the near side. However, at the region $l<0^\circ$ and $|b|\le6^\circ$, the near side is even more metal-poor than the far side, and their difference changes with the Galactic longitude. This is mainly due to the fact that stars around the minor axis of the bar are more metal-poor than those around the major axis. Since the bar is tilted, in the negative longitude region, the near side is mainly contributed by stars close to the minor axis region than the far side to result in such metallicity difference. We extract stars in the X-shape structure by identifying the overdensities in the near and far sides. Their metallicity properties are consistent with the results of the whole Galactic bulge. The boxy/peanut-shaped bulge can naturally explain the metallicity difference of the double red clump stars in observation. There is no need to involve a classical bulge component with different stellar populations.
分类： 物理学 >> 核物理学 提交时间： 2023-08-29
摘要： The sensitivity of an experiment to detect the Majorana neutrino mass via neutrinoless double beta decay (0) strongly depends on the rate of background events that can mimic this decay. One major source of this background is the radioactive emissions from the laboratory environment. In our study, we focused on assessing the background contributions from environmental gamma rays, neutrons, and underground muons to the Jinping bolometric demonstration experiment. This experiment uses an array of lithium molybdate crystal bolometers to probe the potential 0 decay of the 100Mo isotope at the China Jinping Underground Laboratory. We also evaluated the shielding effectiveness of the experimental setup through an attenuation study. Our simulations indicate that the combined background from environmental gamma rays, neutrons, and muons in the relevant 100Mo 0 Q-value region can be reduced to approximately 0.003 cts/kg/keV/yr.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Integrated quantum memories are a scalable solution to synchronize a large number of quantum computers, which are essential to build a quantum network to boost their capabilities on information processing. Rather than expecting to find a specific kind of atoms to meet all the requirements of a good quantum memory, as other protocols usually do, we propose that assigning the memory requirements on coherence property and control property to rare earth ions and lithium niobate crystal, respectively. In particular, optical quantum states are stored into erbium doped lithium niobate (Er$^{3+}$:LiNbO$_3$) micro-cavity by utilizing the electro-optic effect of LiNbO$_3$. The Er$^{3+}$:LiNbO$_3$ cavity frequency can be shifted by an external electric field, which is used to control the photon-echo emission by changing the resonance condition between micro-cavity and collective atomic excitation. According to calculations, high efficiency and low noise storage can be achieved. Benefiting from the host lithium-niobate thin film, such a device can be controlled by on-chip electrodes and is easy to be integrated with modern photonic devices, paving way of integrated quantum chips.
分类： 心理学 >> 心理测量 分类： 心理学 >> 临床与咨询心理学 分类： 医学、药学 >> 临床医学 提交时间： 2024-03-12
摘要： Objective: This study aimed to develop and validate the Chinese Short Version of the Adult ADHD Self-Report Scale (ASRS-CSV), addressing the need for culturally appropriate diagnostic tools for Attention-Deficit Hyperactivity Disorder (ADHD) in the Chinese adult population.Methods: Utilizing a combination of intergroup difference analysis, factor analysis, and network analysis, we identified core ADHD symptoms pertinent to the Chinese cultural context. The study involved two samples: a vocational and technical school sample (N=1144) and an internet sample (N=1654), comprising adults aged 16-25 years. Reliability, validity, and diagnostic efficacy of the ASRS-CSV were assessed through psychometric testing.Results: The ASRS-CSV demonstrated high internal consistency (Cronbach’s alpha > 0.9) and robust convergent validity (AVE > 0.7). The scale’s diagnostic cutoff points were optimized, revealing high sensitivity and specificity for ADHD screening. Cross-cultural analysis highlighted differences in core ADHD symptoms between Chinese and Western populations, underscoring the scale’s cultural sensitivity.Conclusion: The ASRS-CSV is a reliable, valid, and efficient tool for screening ADHD in Chinese adults, reflecting the socio-cultural nuances of ADHD symptomatology. Its development marks a significant advancement in the field of psychiatry, offering a tailored approach for ADHD assessment in China and contributing to the global discourse on cross-cultural psychiatric diagnosis.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Whispering gallery mode (WGM) cavity is important for exploring physics of strong light-matter interaction. Yet it suffers from the notorious radiation loss universally due to the light tunneling effect through the curved boundary. In this work, we propose and demonstrate an optical black hole (OBH) cavity based on transformation optics. The radiation loss of all WGMs in OBH cavity is completely inhibited by an infinite wide potential barrier. Besides, the WGM field outside the cavity is revealed to follow $1/r^\alpha$ decay rule based on conformal mapping, which is fundamentally different from the conventional Hankel-function distributions in a homogeneous cavity. Experimentally, a truncated OBH cavity is achieved based on the effective medium theory, and both the Q-factor enhancement and tightly confined WGM field are measured in the microwave spectra which agree well with the theoretical results. The circular OBH cavity is further applied to the arbitrary-shaped cavities including single-core and multi-core structures with high-Q factor via the conformal mapping. The OBH cavity design strategy can be generalized to resonant modes of various wave systems, such as acoustic and elastic waves, and finds applications in energy harvesting and optoelectronics.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： By modulating the intensity of laser light before the rotating groundglass, the well-known pseudothermal light source can be modified into superbunching pseudothermal light source, in which the degree of second-order coherence of the scattered light is larger than 2. With the modulated intensities following binary distribution, we experimentally observed the degree of second- and third-order coherence equaling 20.45 and 227.07, which is much larger than the value of thermal or pseudothermal light, 2 and 6, respectively. Numerical simulation predicts that the degree of second-order coherence can be further improved by tuning the parameters of binary distribution. It is also predicted that the quality of temporal ghost imaging can be improved with this superbunching pseudothermal light. This simple and efficient superbunching pseudothermal light source provides an interesting alternative to study the second- and higher-order interference of light in these scenarios where thermal or pseudothermal light source were employed.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Nanoscale materials usually can trap light and strongly interact with it leading to many photonic device applications. The light-matter interactions are commonly probed by optical spectroscopy, which, however, have some limitations such as diffraction-limited spatial resolution, tiny momentum transfer and non-continuous excitation/detection. In this work, using scanning transmission electron microscopy-electron energy loss spectroscopy (STEM-EELS) with ultra-wide energy and momentum match and sub-nanometer spatial resolution, we study the optical microcavity resonant spectroscopy in a single SiC nanowire. The longitudinal Fabry-Perot (FP) resonating modes and the transverse whispering-gallery modes (WGMs) are simultaneously excited and detected, which span from near-infrared (~ 1.2 {\mu}m) to ultraviolet (~ 0.2 {\mu}m) spectral regime and the momentum transfer can be ranging up to 108 cm{^{-1}}. The size effects on the resonant spectra of nanowires are also revealed. Moreover, the nanoscale decay length of resonant EELS is revealed, which is contributed by the strongly localized electron-photon interactions in the SiC nanowire. This work provides a new alternative technique to investigate the optical resonating spectroscopy of a single nanowire structure and to explore the light-matter interactions in dielectric nanostructures, which is also promising for modulating free electrons via photonic structures.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Due to the complex of mixed spectral point spread function within memory effect range, it is unreliable and slow to use speckle correlation technology for non-invasive imaging through scattering medium under broadband illumination. The contrast of the speckles will drastically drop as the light source's spectrum width increases. Here, we propose a method for producing the optical transfer function with several speckle frames within memory effect range to image under broadband illumination. The method can be applied to image amplitude and color objects under white LED illumination. Compared to other approaches of imaging under broadband illumination, such as deep learning and modified phase retrieval, our method can provide more stable results with faster convergence speed, which can be applied in high speed scattering imaging under natural light illumination.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Shuanghao Zhang
Huaibin Zheng
Gao Wang
Hui Chen
Jianbin Liu
Yu Zhou
Yuchen He
Sheng Luo
Yanyan Liu
Zhuo Xu
摘要： Stronger light intensity fluctuations are pursued by related applications such as optical resolution, image enhancement, and beam positioning. In this paper, an Nth-order light intensity fluctuation amplifier is proposed, which was demonstrated by a four-wave mixing process with different statistical distribution coupling lights. Firstly, its amplification mechanism is revealed both theoretically and experimentally. The ratio $R$ of statistical distributions and the degree of second-order coherence ${g^{(2)}}(0)$ of beams are used to characterize the affected modulations and the increased light intensity fluctuations through the four-wave mixing process. The results show that the amplification of light intensity fluctuations is caused by not only the fluctuating light fields of incident coupling beams, but also the fluctuating nonlinear coefficient of interaction. At last, we highlight the potentiality of applying such amplifier to other N-order nonlinear optical effects.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Qian-Hui Chen
Kathryn Grasha
Andrew J. Battisti
Lisa J. Kewley
Barry F. Madore
Mark Seibert
Jeff A. Rich
Rachael L. Beaton
摘要： Bars play an important role in mixing material in the inner regions of galaxies and stimulating radial migration. Previous observations have found evidence for the impact of a bar on metallicity gradients but the effect is still inconclusive. We use the TYPHOON/PrISM survey to investigate the metallicity gradients along and beyond the bar region across the entire star-forming disk of five nearby galaxies. Using emission line diagrams to identify star-forming spaxels, we recover the global metallicity gradients ranging from -0.0162 to -0.073 dex/kpc with evidence that the galactic bars act as an agent in affecting in-situ star formation as well as the motions of gas and stars. We observe cases with a `shallow-steep' metallicity radial profile, with evidence of the bar flattening the metallicity gradients inside the bar region (NGC~5068 and NGC~1566) and also note instances where the bar appears to drive a steeper metallicity gradient producing `steep-shallow' metallicity profiles (NGC~1365 and NGC~1744). For NGC~2835, a `steep-shallow' metallicity gradient break occurs at a distance $\sim$ 4 times the bar radius, which is more likely driven by gas accretion to the outskirt of the galaxy instead of the bar. The variation of metallicity gradients around the bar region traces the fluctuations of star formation rate surface density in NGC~1365, NGC~1566 and NGC~1744. A larger sample combined with hydrodynamical simulations is required to further explore the diversity and the relative importance of different ISM mixing mechanisms on the gas-phase metallicity gradients in local galaxies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Alex M. Garcia
Paul Torrey
Z. S. Hemler
Lars Hernquist
Lisa J. Kewley
Erica J. Nelson
Kathryn Grasha
Henry R. M. Zovaro
Qian-Hui Chen
摘要： We present radial gas-phase metallicity profiles, gradients, and break radii at redshift $z = 0 - 3$ from the TNG50-1 star-forming galaxy population. These metallicity profiles are characterized by an emphasis on identifying the steep inner gradient and flat outer gradient. From this, the break radius, $r_{\rm Break}$, is defined as the region where the transition occurs. We observe the break radius having a positive trend with mass that weakens with redshift. When normalized by the stellar half-mass radius, the break radius has a weaker relation with both mass and redshift. To test if our results are dependent on the resolution or adopted physics of TNG50-1, the same analysis is performed in TNG50-2 and Illustris-1. We find general agreement between each of the simulations in their qualitative trends; however, the adopted physics between TNG and Illustris differ and therefore the breaks, normalized by galaxy size, deviate by a factor of $\sim$2. In order to understand where the break comes from, we define two relevant time-scales: an enrichment time-scale and a radial gas mixing time-scale. We find that $r_{\rm Break}$ occurs where the gas mixing time-scale is $\sim$10 times as long as the enrichment time-scale in all three simulation runs, with some weak mass and redshift dependence. This implies that galactic disks can be thought of in two-parts: a star-forming inner disk with a steep gradient and a mixing-dominated outer disk with a flat gradient, with the break radius marking the region of transition between them.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yifeng Xiong
Yushu Wang
Runze Zhu
Haotian Xu
Chenhui Wu
Jin-hui Chen
Yang Ma
Yuan Liu
Ye Chen
K. Watanabe
T. Taniguchi
Mengzhu Shi
Xianhui Chen
Yanqing Lu
Peng Zhan
Yufeng Hao
Fei Xu
摘要： The real-time, in-line analysis of light polarization is critical in optical communication networks, which suffers from the complex systems with numerous bulky opto-electro-mechanical elements tandemly arranged along optical path. Here, we propose a fiber-integrated polarimeter with nano-thickness by vertically stacking three two-dimensional (2D) materials based photodetection units. We demonstrate a self-power-calibrated, ultrafast, unambiguous detection of linear (LP) and circular polarized (CP) light according to the symmetry broken induced linear photogalvanic effects (LPGE) and circular photogalvanic effects (CPGE) in black phosphorous (BP) units, which are twistedly stacked to substitute traditional mechanical rotation of polarizers. As a demonstration, we achieve Hadamard single-pixel polarimetric imaging by the polarimeter to recognize the polarization distributions, showing potential in high-speed polarization-division-multiplexed imaging and real-time polarized endoscopy. This work provides a new strategy for next-generation ultracompact optical and optoelectronic systems, and guides a way for developing high-resolution arrayed devices with multifunctional pixels.
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