分类： 物理学 >> 普通物理:统计和量子力学,量子信息等 分类： 计算机科学 >> 计算机科学技术其他学科 提交时间： 2024-05-14
摘要： In his 1950 paper 11 , Turing proposed the notion of a thinking machine, namely a machine that can think. But a thinking machine has to follow a certain law of physics, provided it is realized physically. In this paper, we show that Turing’s thinking machine necessrily obeys ’t Hooft’s principle of superposition of states, which was presented by ’t Hooft 8 in 2016 beyond the usual one as described by Dirac 4 in the conventional quantum mechanics. Precisely, Turing’s thinking machine must be a quantum machine, while ’t Hooft’s principle characterizes its thinking behavior in a probabilistic way.
分类： 管理学 >> 管理理论 分类： 图书馆学、情报学 >> 情报资料的利用 分类： 其他 >> 综合 提交时间： 2024-05-12
摘要： 目的/意义 阿罗不可能定理是1972年诺贝尔经济学奖的获得者之一肯尼斯·约瑟夫·阿罗陈述和证明的，《新编经济金融词典》在定义阿罗不可能定理时把“一个合理的公共产品决定只能来自于一个可以胜任的公共权力机关”作为阿罗不可能定理的推论，这一推论关系在网络上广为传播，在课堂上广为传授，随着阿罗不可能定理而确立为正确的论断。但这种推论关系不严谨，甚至是错误的，会将我国公共选择学、公共经济学、福利经济学和行政法学等多学科的研究引入歧途，因此有必要正本清源，从学理上纠正，推动相关学科朝着正确的方向发展。 方法/过程 运用文献考证法，对该推论关系的起源和发展进行梳理，厘清相关概念在不同学科的内涵、外延、以及相关概念间关系的演变逻辑，考证阿罗不可能定理和公共产品决策之间的关系。 结果/结论 相关文献表明，一个合理的公共产品决定只能来自于一个可以胜任的公共权力机关的论断，最早是在《行政强制与公共利益的实现》一文中与阿罗不可能定理产生关联，后来被《新编经济金融词典》编写阿罗不可能定理的条目时摘录，成为阿罗不可能定理的推论,具有了只要阿罗不可能定理成立，公共产品只能由公共权力机关强加或者独裁的意义。在此过程中，公共产品和公共权力机关的概念内涵在不同学科语境中发生偏移，两者关系的逻辑基础也发生演变，因而把一个合理的公共产品决定只能来自于一个可以胜任的公共权力机关的论断作为阿罗不可能定理的推论不是很严谨。阿罗不可能定理的确会引起公共产品决策难题，但公共选择领域的研究并不认为这一决策难题应该交由公共权力机关强加或独裁，相反，他们致力于投票机制的制度设计，以确保公共产品提供是由公众来决定的。
分类： 药物科学 >> 其他 分类： 医学、药学 >> 药学 提交时间： 2024-05-10
Yingquan WEN
Ziyuan ZOU
Guanguan ZHAO
Mengjiao ZHANG
Yongxin ZHANG
Gaihong WANG
Jingjing SHI
Yuanyang WANG
Yeyu SONG
Huixia WANG
Ruyue CHEN
Dongxuan ZHENG
Xiaoqun DUAN
Yameng LIU
Frank J GONZALEZ
Jian-Gao FAN
Cen XIE
摘要： The progression of simple steatosis to non-alcoholic steatohepatitis (NASH) has emerged as a significant health concern. The activation of FXR shows promise in countering this transition and its detrimental consequences. However, the specific alterations within the NASH-related transcriptional network remain elusive, hindering the development of more precise and effective therapeutic strategies. Through a comprehensive analysis of liver RNA-seq data from human and mouse NASH samples, we identified central perturbations within the NASH-associated transcriptional network, including disrupted cellular metabolism and mitochondrial function, decreased tissue repair capability, and increased inflammation and fibrosis, thus shedding light on the complex molecular mechanisms underlying NASH progression. By employing integrated transcriptome profiling of diverse FXR agonists-treated mice, FXR liver-specific knockout mice, and publicly available human datasets, we determined that hepatic FXR activation effectively ameliorated NASH by reversing the dysregulated metabolic and inflammatory networks implicated in NASH pathogenesis. This mitigation encompassed resolving fibrosis, reducing immune infiltration, and creating an immune microenvironment that mirrors the positive trends observed in clinical disease progression. By understanding the core regulatory network of FXR, which is directly correlated with disease severity and treatment response, we identified approximately one-third of the patients who could potentially benefit from FXR agonist therapy. A similar analysis involving intestinal RNA-seq data from FXR agonists-treated mice and FXR intestine-specific knockout mice revealed that intestinal FXR activation attenuates intestinal inflammation, and has promise in attenuating hepatic inflammation and fibrosis. Collectively, our study uncovers the intricate pathophysiological features of NASH at a transcriptional level and highlights the complex interplay between FXR activation and both NASH progression and regression. These findings contribute to precise drug development, utilization, and efficacy evaluation, ultimately aiming to improve patient outcomes.
分类： 工程与技术科学 >> 物理学相关工程与技术 分类： 工程与技术科学 >> 仪器仪表技术 分类： 电子与通信技术 >> 电子技术 分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间： 2024-05-06
摘要： 本文提出了一种用于低温扫描隧道显微镜(CryoSTM)的跨阻放大器(TIA)设计方案。在CryoSTM中带有尖端样品成分的TIA称为CryoSTM-TIA。该CryoSTM-TIA的跨阻增益在1Gohm，而其带宽大于300kHz。所提出的CryoSTM-TIA的独特特点是其前置放大器由单个低温高电子迁移率晶体管(HEMT)制成，因此在100kHz时仪器等效输入噪声电流功率谱密度低于4(fA)2/Hz。此外，应用“偏置冷却法”可用于原位控制HEMT掺杂区冻结DX-中心的密度，改变其结构以降低器件噪声。利用该仪器，可以进行高能量分辨率的快速扫描隧道光谱测量。并且，它能够测量各种量子系统在原子尺度上的扫描隧道散粒噪声谱(STSNS)，即使散粒噪声非常低。它为通过测量STSNS来研究新的量子态提供了一个强大的工具，例如检测拓扑量子系统中马约拉纳束缚态的存在。
分类： 电子与通信技术 >> 电子技术 分类： 工程与技术科学 >> 仪器仪表技术 分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 分类： 物理学 >> 凝聚态:电子结构、电、磁和光学性质 提交时间： 2024-05-06
摘要： In this work, we design and fabricate the transimpedance Amplifier (TIA) following the design mentioned in Ref. cite{Liang2024}. In the TIA, the preamplifier (Pre-Amp) is made of a junction field effect transistor (JFET) that can work at 77 K. The post-amplifier is made of an operational amplifier (OPA). Cascade Pre-Amp and Post-Amp to form the inverting-amplifier (Inv-Amp). The gain-bandwidth product of Inv-Amp with the gain about 50,000 is higher than 10 GHz. With a 1.13 Gohm feedback network, the gain of TIA is 1.13 Gohm and its bandwidth is about 97 kHz. The equivalent input noise voltage power spectral density of TIA is not more than 9 (nV)2/Hz at 10 kHz and 4 (nV)2/Hz at 50kHz, and its equivalent input noise current power spectral density is about 26 (fA)2/Hz at 10 kHz and 240(fA)2/Hz at 50 kHz. The measured transport performances and noise performances of TIA are consistent with the simulations and calculations, verifying the feasibility for the design of low-noise large-bandwidth TIA proposed in Ref. 1 . And, TIA with various performances that meet various needs can be designed according to the design methods in Ref. 1,2 . With the same gain, the bandwidth of the TIA in this work is much larger than the present TIA and its noises are much lower than those of present ones. The TIA in this work is perfect for the cryogenic STM working at 77 K (i.e. liquid nitrogen temperature).
分类： 物理学 >> 核物理学 分类： 生物学 >> 放射生物学 提交时间： 2024-05-06
摘要： 我国载人航天和核技术应用正处于快速发展阶段，辐射与核安全仍将长期成为国家重大需求，持续开发新的辐射防护分子靶标和相关药物具有重要价值。先前的研究已发现电离辐射暴露后小鼠血液中的胰岛素样生长因子结合蛋白3（IGFBP-3）的水平显著上升，但是，IGFBP-3蛋白的功能及其血液水平的变化对小鼠辐射损伤的影响仍不清楚。本研究在小鼠肝脏巨噬细胞（Kupffer细胞，MKC）中建立了Igfbp3基因过表达和敲低细胞模型，利用CCK-8、EdU掺入、克隆形成和微球吞噬实验对碳离子照射后不同细胞模型的增殖活力、DNA复制活性和吞噬能力进行检测；在小鼠模型中，通过在照射前2小时尾静脉注射重组IGFBP-3蛋白提前升高血液IGFBP-3蛋白水平，检测致死剂量（5 Gy）碳离子全身照射后小鼠的生存曲线。结果显示，过表达IGFBP-3蛋白显著提高了MKC细胞在辐射暴露后的DNA复制活性、细胞活力、克隆形成率和对微球的吞噬能力，相反地，敲低IGFBP-3蛋白表达则降低了以上检测指标。碳离子辐射暴露前尾静脉注射IGFBP-3蛋白可以显著延缓急性放射损伤小鼠的死亡时间。以上结果从细胞和动物水平表明了IGFBP-3蛋白具有减轻辐射损伤的作用和作为辐射防护药靶的巨大潜力。通过增强小鼠体内Kupffer细胞的辐射抗性和吞噬能力来降低辐射暴露后的感染风险可能是IGFBP-3蛋白发挥辐射防护作用的机制之一。
分类： 医学、药学 >> 预防医学与公共卫生学 分类： 统计学 >> 生物与医学统计学 提交时间： 2024-05-06
摘要： 极端不平衡数据定义为自变量或因变量指标的取值呈现严重比例失衡的数据，例如病例-对照极度不平衡、疾病发病率极低、生存数据大量删失以及遗传位点为低频或罕见变异等。在此情境下，logistic回归模型、Cox比例风险模型等参数假设检验的经典统计量偏离正态分布，难以控制一类错误。近年来，随着超大型人群队列全基因组关联研究资源的日益共享与深度挖掘，高效准确处理独立或非独立样本极端不平衡数据的统计需求日益突出。为此，本文系统地进行了方法学概述。首先，综述常见经典统计量理论推导的原理；其次，阐述极端不平衡数据对统计量分布的影响；然后，介绍遗传统计学中常用的两种统计量校正方法：Firth校正和鞍点近似方法；最后，简介极端不平衡基因组学数据常用软件。本文为极端不平衡数据的统计分析提供理论参考和应用推荐。
分类： 物理学 >> 核物理学 分类： 核科学技术 >> 核探测技术与核电子学 提交时间： 2024-04-28
摘要： A charged particle array, named MATE-PA, which serves as an auxiliary detec#2;tor system to the Multi-purpose Active-target Time projection chamber for nuclear astrophysical and exotic beam Experiments (MATE) has been con#2;structed. The array is composed of twenty single-sided strip-silicon detectors, covering around 10% of the solid angle. It is dedicated for the detection of reaction-induced charged particles which penetrate the MATE active volume. The performance of MATE-PA has been experimentally studied using an alpha source, and a 36-MeV 14N beam injected into the chamber of MATE, filled with a mixture gas of 95% 4He and 5% CO2 under the pressure of 500 mbar, at the Radioactive Ion Beam Line in Lanzhou (RIBLL). The results demonstrate good separation of light charged particles with the forward double-layer silicon detectors of MATE-PA. The energy resolution of the Si detectors was deduced to be about 1% (σ) for an energy loss of about 10 MeV by the α particles. The inclusion of MATE-PA helps improve particle identification, and increases the dynamic range for the kinetic energy of charged particles, in particular that of α particles up to about 15 MeV.
分类： 其他 分类： 其他 提交时间： 2024-04-25
摘要： The Australia Telescope Large Area Survey (ATLAS) and the VLA survey in the XMM-LSS/VIDEO deep field provide deep ($\approx 15$ ${\mu}$Jybeam$^{-1}$) and high-resolution ($\approx$ 4.5--8 arcsec) radio coverage of the three XMM-SERVS fields (W-CDF-S, ELAIS-S1, and XMM-LSS). These data cover a total sky area of 11.3 deg$^2$ and contain $\approx 11000$ radio components. Furthermore, about 3~deg$^2$ of the XMM-LSS field also has deeper MIGHTEE data that achieve a median RMS of 5.6 ${\mu}$Jy beam$^{-1}$ and detect more than 20000 radio sources. We analyze all these radio data and find source counterparts at other wavebands utilizing deep optical and IR surveys. The nature of these radio sources is studied using radio-band properties (spectral slope and morphology), and the IR-radio correlation. %and spectral energy distribution. Radio AGNs are selected and compared with those selected using other methods (e.g. X-ray). We found 1656 new AGNs that were not selected using X-ray and/or MIR methods. We constrain the FIR-to-UV SEDs of radio AGNs using {\sc cigale} and investigate the dependence of radio AGN fraction upon galaxy stellar mass and star-formation rate.
分类： 其他 分类： 其他 提交时间： 2024-04-25
摘要： We present X-ray spectral and long-term variability analyses of an unbiased sample of 361 optically selected radio-loud quasars (RLQs) utilizing sensitive serendipitous X-ray data from the Chandra and XMM-Newton archives. The spectral and temporal properties of RLQs are compared with those of radio-quiet quasars (RQQs) matched in $L_\mathrm{2500A}$ and $z$. The median power-law photon index ($\Gamma$) of RLQs is $1.84^{+0.01}_{-0.01}$, which is close to that of matched RQQs ($1.90^{+0.02}_{-0.01}$). No significant correlations between $\Gamma$ and radio-loudness, $L_\mathrm{x}/L_\mathrm{x,rqq}$ (the X-ray luminosity over that expected from the $L_\mathrm{x}$-$L_\mathrm{uv}$ relation for RQQs), redshift, or Eddington ratio are found for our RLQs. The stacked X-ray spectra of our RLQs show strong iron-line emission and a possible Compton-reflection hump. The intrinsic X-ray variability amplitude is $\approx40$% for RLQs on timescales of months-to-years in the rest frame, which is somewhat smaller than for the matched RQQs ($\approx60$%) on similar timescales, perhaps due to the larger black-hole masses and lower Eddington ratios in our RLQ sample. The X-ray spectral and variability results for our RLQs generally support the idea that the X-ray emission of typical RLQs is dominated by the disk/corona, as is also indicated by a recent luminosity correlation study.
分类： 其他 分类： 其他 提交时间： 2024-04-25
摘要： Radio-loud quasars (RLQs) are known to produce excess X-ray emission, compared to radio-quiet quasars (RQQs) of the same luminosity, commonly attributed to jet-related emission. Recently, we found that the HeII EW and $\alpha_{\rm{ox}}$ in RQQs are strongly correlated, which suggests that their extreme-ultraviolet (EUV) and X-ray emission mechanisms are tightly related. Using 48 RLQs, we show that steep-spectrum radio quasars (SSRQs) and low radio-luminosity ($L_{\rm R}$) flat-spectrum radio quasars (FSRQs) follow the $\alpha_{\rm ox}$--HeII EW relation of RQQs. This suggests that the X-ray and EUV emission mechanisms in these types of RLQs is the same as in RQQs, and is not jet related. High-$L_{\rm R}$ FSRQs show excess X-ray emission given their HeII EW by a factor of $\approx$ 3.5, which suggests that only in this type of RLQ is the X-ray production likely jet related.
分类： 其他 分类： 其他 提交时间： 2024-04-25
摘要： Radio-loud quasars (RLQs) are more X-ray luminous than predicted by the X-ray-optical/UV relation (i.e. $L_\mathrm{x}\propto L_\mathrm{uv}^\gamma$) for radio-quiet quasars (RQQs). The excess X-ray emission depends on the radio-loudness parameter ($R$) and radio spectral slope ($\alpha_\mathrm{r}$). We construct a uniform sample of 729 optically selected RLQs with high fractions of X-ray detections and $\alpha_\mathrm{r}$ measurements.We find that steep-spectrum radio quasars (SSRQs; $\alpha_\mathrm{r}\le-0.5$) follow a quantitatively similar $L_\mathrm{x}\propto L_\mathrm{uv}^\gamma$ relation as that for RQQs, suggesting a common coronal origin for the X-ray emission of both SSRQs and RQQs. However, the corresponding intercept of SSRQs is larger than that for RQQs and increases with $R$, suggesting a connection between the radio jets and the configuration of the accretion flow. Flat-spectrum radio quasars (FSRQs; $\alpha_\mathrm{r}>-0.5$) are generally more X-ray luminous than SSRQs at given $L_\mathrm{uv}$ and $R$, likely involving more physical processes. The emergent picture is different from that commonly assumed where the excess X-ray emission of RLQs is attributed to the jets. We thus perform model selection to comparecritically these different interpretations, which prefers the coronal scenario with a corona-jet connection. A distinct jet component is likely important for only a small portion of FSRQs.The corona-jet, disk-corona, and disk-jet connections of RLQs are likely driven by independent physical processes. Furthermore, the corona-jet connection implies that small-scale processesin the vicinity of SMBHs, probably associated with the magnetic flux/topology instead of black-hole spin, are controlling the radio-loudness of quasars.
分类： 其他 分类： 其他 分类： 其他 提交时间： 2024-04-25
摘要： Fluxes emitted at different wavebands from active galactic nuclei (AGNs) fluctuate at both long and short timescales. The variation can typically be characterized by a broadband power spectrum, which exhibits a red-noise process at high frequencies. The standard method of estimating power spectral density (PSD) of AGN variability is easily affected by systematic biases such as red-noise leakage and aliasing, in particular, when the observation spans a relatively short period and is gapped. Focusing on the high-frequency PSD that is strongly distorted due to red-noise leakage and usually not significantly affected by aliasing, we develop a novel and observable normalized leakage spectrum (NLS), which describes sensitively the effects of leaked red-noise power on the PSD at different temporal frequencies. Using Monte Carlo simulations, we demonstrate how an AGN underlying PSD sensitively determines the NLS when there is severe red-noise leakage and thereby how the NLS can be used to effectively constrain the underlying PSD.
分类： 心理学 >> 发展心理学 分类： 心理学 >> 教育心理学 提交时间： 2024-04-23
摘要： 对185名二年级儿童进行历时20个月的两波次追踪，考察了二年级的家庭社会经济地位对二、三年级数学运算能力、逻辑思维能力和空间想象能力的预测作用，以及干扰抑制、反应抑制和工作记忆在其中的中介作用。研究发现：(1)二年级的家庭社会经济地位仅对二年级时的三种数学能力具有直接预测作用。(2)家庭社会经济地位可以通过工作记忆的中介作用间接预测二年级的数学运算能力和三年级的逻辑思维能力。这表明执行功能在家庭社会经济地位与数学能力关系中的作用会随执行功能成分类型、数学能力类型及测试时间点而发生变化。
分类： 计算机科学 >> 信息安全 分类： 计算机科学 >> 计算机应用技术 提交时间： 2024-04-23
摘要： Image steganography has become a focal point of interest for researchers due to its capacity for the covert transmission of sensitive data. Traditional diffusion models often struggle with image steganography tasks involving paired data, as their core principle of gradually removing noise is not directly suited for maintaining the correspondence between carrier and secret information. To address this challenge, this paper conducts an in-depth analysis of the principles behind diffusion models and proposes a novel framework for an image steganography diffusion model. The study begins by mathematically representing the steganography tasks of paired images, introducing two optimization objectives: minimizing the secrecy leakage function and embedding distortion function. Subsequently, it identifies three key issues that need to be addressed in paired image steganography tasks and, through specific constraint mechanisms and optimization strategies, enables the diffusion model to effectively handle paired data. This enhances the quality of the generated stego-images and resolves issues such as image clarity. Finally, on public datasets like CelebA, the proposed model is compared with existing generation model-based image steganography techniques, analyzing its implementation effects and performance parameters. Experimental results indicate that, compared to current technologies, the model framework proposed in this study not only improves image quality but also achieves significant enhancements in multiple performance metrics, including the imperceptibility and anti-detection capabilities of the images. Specifically, the PSNR of its stego-images reaches 93.14dB, and the extracted images’ PSNR reaches 91.23dB, an approximate improvement of 30% over existing technologies; the attack success rate is reduced to 2.4x10-38. These experimental outcomes validate the efficacy and superiority of the method in image steganography tasks.
分类： 计算机科学 >> 计算机软件 分类： 语言学及应用语言学 >> 语言学及应用语言学 提交时间： 2024-04-21
摘要： 此幻灯片从背景、动机、方法、效果、展望和致谢六方面讲述了《引导大语言模型生成计算机可解析内容》的研究。全文请参考：https://arxiv.org/abs/2404.05499
分类： 天文学 >> 天体力学 分类： 物理学 >> 地球物理学、天文学和天体物理学 提交时间： 2024-04-20
摘要： 本文简要介绍新的对称形式的质点动力学方程对天体动力学理论的系统性改进。 首先，对于开放的多体系统，无法找到近似程度非常高的惯性系，在传统理论中不得不引入惯性系的近似，而对称新方程因为可以直接适用于任意的平动参考系而避免了惯性系的近似，从而可以提高理论预言的精度。其次，对于束缚的多体系统，传统理论的动力学应用是先引入质心参考系，在质心参考系中应用牛顿第二定律，然后通过坐标变换再转化到实体参考系，比如太阳系的行星摄动方程。 但是，应用对称新方程则可以一步到位推导得到行星摄动方程。最后，如果进一步考虑行星受到临时推力或者冲击力，甚至为了进一步提高计算精度进而考虑来自束缚系统外的作用力，则一个可以叠加非微扰作用力的行星摄动的修正方程在本文得到了确立。
分类： 心理学 >> 实验心理学 分类： 心理学 >> 社会心理学 提交时间： 2024-04-20
摘要： 情绪能够强化记忆编码且对后续记忆编码也有增强效果。本研究探索复杂社会情绪（即民族危机感和自豪感）唤醒如何影响后续的记忆编码。在问卷调查的基础上，研究利用两个实验探索民族情绪唤醒如何选择性地增强记忆编码。实验2采用被试间设计，参与者被随机分配到危机感、自豪感及中性情绪组进行情绪唤醒，随后进行记忆编码。结果显示，民族危机感和自豪感的唤醒显著增强了记忆编码，但对同一时间窗内与民族情绪无关图片记忆无显著影响。实验3采用相同的设计，但更换记忆材料为数学统计概念，结果发现民族情绪唤醒不影响数学统计记忆编码。本研究深化了我们对复杂社会情绪与记忆交互作用的理解，同时为优化高校思想政治教育提供了实证基础。
分类： 图书馆学、情报学 >> 各种文献工作 分类： 图书馆学、情报学 >> 图书馆学 提交时间： 2024-04-18
摘要： 目的 知识可视化设计研究综述反映了人们对知识新形式的探索路径。 文献范围 国外文献来自Web of Science的核心合集数据库论文1377篇。国内文献来自知网518篇论文数据。 方法 研究借助文献计量分析工具Vosview、Citespace 以及自主梳理方法，以“知识可视化设计”为关键词对1985-2022年间国内外文献进行检索和分析，解析了知识可视化设计研究的辩证发展路径。 结果 发现目前可视化定义研究的局限，研究对知识可视化设计的本体论和认识论上缺乏思考，以及过于依赖单一的研究视角缺乏辩证思维。 局限 由于国内外数据库不统一较难用同种方法进行统一分析。 结论 中国知识可视化设计者和研究者应用唯物辩证法把握知识可视化设计领域研究脉络和规律，了解其辩证发展过程，找到中国知识可视化领域的发展道路。
分类： 心理学 >> 认知心理学 分类： 心理学 >> 心理统计 提交时间： 2024-04-17
摘要： 认知建模近年来在科学心理学获得广泛应用，而模型比较是认知建模中关键的一环：研究者需要通过模型比较来选择出最优模型，才能进行后续的假设检验或潜变量推断。模型比较不仅要考虑模型对数据的拟合（平衡过拟合与欠拟合），也需要考虑参数数据和数学形式的复杂度。然而，模型比较指标众多，纷繁复杂。将认知建模常用的模型比较的指标分为三大类，并介绍了其计算方法及优劣，包括拟合优度指标（包括均方误差、决定系数、ROC曲线等）、基于交叉验证的指标（包括AIC、DIC等）和基于边际似然的指标。结合正交Go /No-Go范式下的模拟数据和真实数据，展示各指标在R语言中如何实现。在此基础上，探讨各指标的适用情境，介绍模型平均等模型比较的新思路。
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