分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 随着现代科技的发展，重力学与地震学、地质学、基础物理学、地球动力学、水文学、海洋学和天文 学等众多学科交叉融合并蓬勃发展，是服务国家测绘基准、资源勘探、军事安全及灾害监测等战略需求和基 础地球科学问题研究的关键学科，因此掌握重力学的核心技术是国家核心竞争力的重要体现。文章在分析我 国重力学学科发展的历史、现状、机遇与挑战的基础上，提出了重力学学科未来发展方向与重点思考内容， 涉及海陆天空一体化的立体重力观测技术，海陆天空统一的大地测量重力基准网，地球系统质量迁移与青藏 高原动力学问题研究，面向国防安全与太空的重力学，以及发展人工智能等新技术在重力学研究中的应 用等。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 生命科学发展日新月异，伴随着大量实验技术的更新，生物大数据逐渐产生并在生命科学研究中扮演 着日益重要的角色。首先，生物大数据具有多样性和复杂性，包括基因组数据、表观基因组数据、蛋白质组 数据等多种类型。这些数据为研究人员提供了更全面的信息，有助于揭示生命现象背后的规律。其次，数据 驱动的生命科学新发展和应用涵盖了基因编辑、精准医疗、药物研发等诸多领域，为人类健康和生命质量提 供了前所未有的可能性。然而，生命科学研究大数据时代也面临着包括数据存储、数据共享、隐私保护等多 方面的问题，以及如何将海量数据转化为可靠的科学发现等挑战。文章简要概括了生物数据推动生命科学的 发展规律，梳理了生物大数据组成、特点及来源，阐述并讨论了数据驱动的生命科学研究新范式下的共性问 题和我国面临的挑战。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 新药研发是医药创新发展的关键环节，是新一轮生命科技革命和生物经济变革的核心领域，对引领科 技创新、带动经济发展、提升人民健康福祉具有战略意义。当前，前沿技术不断革新、学科跨域融合、数字 深度赋能驱动新药研发领域创新日趋活跃，国内外创新性小分子药物、抗体药物、免疫细胞治疗、基因治疗 与核酸药物等密集获批上市，为未满足的临床需求提供更多选择。文章深入分析新药研发领域发展趋势、全 球新药批准情况，以及我国新药研发发展现状与态势，提出发展启示与建议，以期为新药研发领域发展提供 参考。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 纳米酶代表了一类新型人工酶和生物催化剂，打破了无机与有机生命的界限。它既有纳米材料的理化 特性，也有独特的类酶催化活性。同时，这些理化特性有可能会调控催化活性，使得纳米酶跟天然酶、传统 的模拟酶和化学催化剂区别开来。纳米酶有比较好的稳定性、耐高温、低温、耐酸碱、活性可调且多功能， 目前受到了广泛关注，在生物医药、环境治理、绿色农业、新能源等领域展现出巨大的应用前景，并初步形 成了相应的学科框架。为了更好地推动纳米酶的发展，拓展对纳米酶的认识，文章回顾了纳米酶发现，分析 凝练了纳米酶的学科特点及其结构，综述了纳米酶的应用，并展望了未来的发展趋势。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 以智能科技为核心技术、智能算力为生产力的智能时代再次把脑科学推向世界科学与技术前沿。脑科 学是研究人、动物和机器的认知与智能的本质和规律的科学。对神经系统结构和功能联结规律进行全面解析 将最终绘制成脑功能联结图谱，近10 多年来神经科学研究致力于系统性地解析神经系统的神经元类型和神经 结构连接，在单细胞转录组分析、神经网络结构示踪等技术推动下取得了阶段性进展。解析人类大脑这一最 为复杂的信息和智能系统，会启迪类脑智能理论和类脑智能技术，即脑科学/神经科学启发的智能理论和技 术。在智能时代，脑科学研究的多学科交叉研究范式促使脑机接口、类脑智能计算等类脑智能研究领域加入 脑科学。脑机接口的神经解码和编码技术为绘制人脑功能神经网络图谱提供了重要的功能研究技术和方法， 并且可探索在脑疾病临床诊治上的应用。类脑计算正成为脑科学研究的一种新范式，借鉴脑处理信息和学习 的基本原理发展高能效、高速和智能的新型类脑计算系统，利用发展的类脑计算系统可以加速发展脑模拟和 数字大脑，促进理解大脑运行机制和治疗脑疾病，发展数字脑科学和脑医学。新近出现的脉冲神经网络智能 处理器为构建大规模类脑智能计算系统奠定了基础，未来类脑超级算力极可能超过人类大脑算力，影响智能 科技变革和人类社会发展。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 实现17 项联合国可持续发展目标（SDGs） 是世界各国在2016—2030 年的重要任务，但近期评估显示 有半数目标进展停滞甚至倒退，并且到2030 年世界各国可能无法实现大多数目标。文章在回顾全球及中国实 现17 项SDGs进展的基础上，总结了影响SDGs实现的5 项主要挑战，包括：数据缺失和监测能力不足，不同 SDGs间相互联系的高度复杂性，区域差异和负外部性影响，科学、政策和社会联系不足，以及全球变化对 SDGs实现的不确定性影响。同时，文章从加强政策一致性、聚焦优先目标、强化基础理论研究、提升数据 获取能力4个方面提出了加快中国实现SDGs的对策建议。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 世纪之交的“人类基因组计划”开启了生命大科学的研究新时代，形成了以整体性高通量研究为特征 的各种生命组学。最初的组学研究主要在分子层次上展开，如基因组学、转录组学、蛋白质组学等，表现出 数据驱动的研究新范式。随着研究技术的发展，组学研究上升到介观层次，其核心是2017 年启动的“人类细 胞图谱”计划。目前，研究者已经能够在组织器官乃至个体水平开展组学研究，通过整合不同层次的组学数 据来认识生命复杂系统。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 新质生产力是一个战略性的概念，可以将其定义为所有能够促进基于技术进步之上提高单位产品科技 含量和附加值的经济活动。讨论新质生产力必须要正确理解基于技术进步之上的产业升级，避免“一刀切”， 将新质生产力限制在特定发展领域，认为新质生产力是技术决定论。发展新质生产力要关注基础研究、应用 技术、金融系统3 个核心生产要素，同时通过推动制度型高水平开放、营造良好的营商环境、打造开放的国 际化人才体系，提供一个有效的发展新质生产力的支持环境。
分类： 统计学 >> 社会统计学 提交时间： 2024-06-28 合作期刊: 《中国科学院院刊》
摘要： 基于生态系统的海洋管理是海洋生态文明建设的重要手段。我国当前的海洋生态分类分区工作通过全 面梳理海洋生态系统类型和自然地理特征，将我国近海按照不同尺度划分为若干等级的生态空间单元，有效 刻画了海洋生物群落及其栖息地的地理分布特征，对于支撑基于生态系统的海洋管理具有重要作用。文章分 析了海洋生态分类分区的现实意义，回顾了国内外海洋生态分类分区研究和发展历程，介绍了我国海洋生态 分类分区的实践经验和应用前景，并对基于生态系统的海洋管理实现路径提出建议。
分类： 医学、药学 >> 临床医学 提交时间： 2024-06-28 合作期刊: 《中国全科医学》
摘要： 背景 腹腔感染是引起脓毒症的常见病因，老年腹腔脓毒症患者死亡率高，正确评估其预后具有重要意义。目前基于计算机断层扫描（CT）评估骨骼肌量成为研究热点，但骨骼肌量对老年腹腔脓毒症患者预后的预测价值鲜见报道。目的 探讨第 3 腰椎（L3）中点平面骨骼肌指数（SMI）联合序贯器官衰竭评估（SOFA）评分、急性生理与慢性健康评分Ⅱ（APACHE Ⅱ）评分对老年腹腔脓毒症患者院内死亡的预测价值。方法 选取 2022-01-01—07-31 就诊于首都医科大学附属北京朝阳医院急诊医学中心的老年腹腔脓毒症患者 335 例为研究对象。依据患者住院期间是否存活分为生存组（250 例）与死亡组（85 例），比较两组的临床资料及基于腹部 CT 的 L3 SMI 水平。利用多因素 Logistic 回归分析探究老年腹腔脓毒症患者院内死亡的影响因素。分别绘制 L3 SMI、SOFA 评分、APACHE Ⅱ评分及联合指标预测患者院内死亡风险的受试者工作特征（ROC）曲线，计算曲线下面积（AUC）并进行比较。结果 335例老年腹腔脓毒症患者的院内病死率为 25.4%（85/335）。两组患者年龄、BMI、白蛋白、肌酐、降钙素原、L3 SMI、营养风险筛查 2002（NRS2002）、脓毒性休克占比、SOFA 评分、APACHE Ⅱ评分比较，差异有统计学意义（P<0.05）。多因素 Logistic 回归分析结果显示，低 L3 SMI（OR=0.924，95%CI=0.886~0.964，P<0.001）、高 NRS2002 评分（OR=1.312，95%CI=1.086~1.585，P=0.005）、高 SOFA评分（OR=1.170，95%CI=1.053~1.300，P=0.004）、高 APACHE Ⅱ评分（OR=1.052，95%CI=1.003~1.103，P=0.038）是老年腹腔脓毒症患者院内死亡的独立危险因素。L3 SMI、SOFA 评分、APACHE Ⅱ评分预测患者院内死亡风险的 AUC 分别为 0.711、0.740、0.742。L3 SMI 联合 SOFA 评分或 APACHE Ⅱ评分将提高其预测效能，AUC 分别为 0.795、0.792。结论 低 L3 SMI 是老年腹腔脓毒症患者院内死亡的独立危险因素，基于腹部 CT的骨骼肌量联合危重症评分系统可有效评估其预后。
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We measure for the first time the outermost edges of the Milky Way (MW) halo in terms of the depletion and turnaround radii. The inner depletion radius, $r_\mathrm{id}$, identified at the location of maximum infall velocity, separates a growing halo from the draining environment, while the turnaround radius, $r_\mathrm{ta}$, marks the outermost edge of infalling material towards the halo, both of which are located well outside the virial radius. Using the motions of nearby dwarf galaxies within $3\mathrm{Mpc}$, we obtain a marginal detection of the infall zone around the MW with a maximum velocity of $v_\mathrm{inf, max}=-46_{-39}^{+24}\mathrm{km s^{-1}}$. This enables us to measure $r_\mathrm{id}=559\pm 107 \mathrm{kpc}$ and $r_\mathrm{ta}=839\pm 121 \mathrm{kpc}$. The measured depletion radius is about 1.5 times the MW virial radius ($R_\mathrm{200m}$) measured from internal dynamics. Compared with halos in the cosmological simulation Illustris TNG100, the factor 1.5 is consistent with that of halos with similar masses and dynamical environments to the MW but slightly smaller than typical values of Local Group analogs, potentially indicating the unique evolution history of the MW. These measurements of halo edges directly quantify the ongoing evolution of the MW outer halo and provide constraints on the current dynamical state of the MW that are independent from internal dynamics.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The Solar System's orbital structure is thought to have been sculpted by an episode of dynamical instability among the giant planets. However, the instability trigger and timing have not been clearly established. Hydrodynamical modeling has shown that while the Sun's gaseous protoplanetary disk was present the giant planets migrated into a compact orbital configuration in a chain of resonances. Here we use dynamical simulations to show that the giant planets' instability was likely triggered by the dispersal of the gaseous disk. As the disk evaporated from the inside-out, its inner edge swept successively across and dynamically perturbed each planet's orbit in turn. The associated orbital shift caused a dynamical compression of the exterior part of the system, ultimately triggering instability. The final orbits of our simulated systems match those of the Solar System for a viable range of astrophysical parameters. The giant planet instability therefore took place as the gaseous disk dissipated, constrained by astronomical observations to be a few to ten million years after the birth of the Solar System. Terrestrial planet formation would not complete until after such an early giant planet instability; the growing terrestrial planets may even have been sculpted by its perturbations, explaining the small mass of Mars relative to Earth.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A general covariant local field theory of the holographic dark energy model is presented. It turns out the low energy effective theory of the holographic dark energy is the massive gravity theory whose graviton has 3 polarisations, including one scalar mode and two tensor modes. The Compton wavelength is the size of the future event horizon of the universe. The UV-IR correspondence in the holographic dark energy model stems from the scalar graviton's strong coupling at the energy scale that marks the breaking down of the effective field theory.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Thermoelastic loss is one of the main energy dissipation mechanisms in resonant systems. A careful analysis of the thermoelastic loss is critical to design low-noise resonators for high-precision applications, such as gravitational-wave detectors. This paper presents an analytical solution to the thermoelastic loss in multimaterial coated finite substrates with realistic assumptions on the model structure and the elastic fields. The mechanism responsible for thermoelastic loss is taken as a function of material properties, operating temperature and frequency, and other design parameters. We calculate the thermoelastic loss for specific applications over a wide range of frequencies (1 Hz to 10 GHz) and temperatures (1 K to 300 K), and for a variety of substrate and coating materials. The result is relevant for gravitational-wave detectors and for experiments sensitive to mechanical dissipation.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Building accurate and predictive models of the underlying mechanisms of celestial motion has inspired fundamental developments in theoretical physics. Candidate theories seek to explain observations and predict future positions of planets, stars, and other astronomical bodies as faithfully as possible. We use a data-driven learning approach, extending that developed in Lu et al. ($2019$) and extended in Zhong et al. ($2020$), to a derive stable and accurate model for the motion of celestial bodies in our Solar System. Our model is based on a collective dynamics framework, and is learned from the NASA Jet Propulsion Lab's development ephemerides. By modeling the major astronomical bodies in the Solar System as pairwise interacting agents, our learned model generate extremely accurate dynamics that preserve not only intrinsic geometric properties of the orbits, but also highly sensitive features of the dynamics, such as perihelion precession rates. Our learned model can provide a unified explanation to the observation data, especially in terms of reproducing the perihelion precession of Mars, Mercury, and the Moon. Moreover, Our model outperforms Newton's Law of Universal Gravitation in all cases and performs similarly to, and exceeds on the Moon, the Einstein-Infeld-Hoffman equations derived from Einstein's theory of general relativity.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Presolar grains are microscopic dust grains that formed in the stellar winds or explosions of ancient stars that died before the formation of the solar system. The majority (~90% in number) of presolar silicon carbide (SiC) grains, including types mainstream (MS), Y, and Z, came from low-mass C-rich asymptotic giant branch (AGB) stars, which is supported by the ubiquitous presence of SiC dust observed in the circumstellar envelope of AGB stars and the signatures of slow neutron-capture process preserved in these grains. Here, we review the status of isotope studies of presolar AGB SiC grains with an emphasis on heavy-element isotopes and highlight the importance of presolar grain studies for nuclear astrophysics. We discuss the sensitives of different types of nuclei to varying AGB stellar parameters and how their abundances in presolar AGB SiC grains can be used to provide independent, detailed constraints on stellar parameters, including 13C formation, stellar temperature, and nuclear reaction rates.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The Messenger Interface Monte-Carlo Mappings V (M^3) is a photoionization code adopting the fully self-consistent Monte-Carlo radiative transfer technique, which presents a major advance over previous photoionization models with simple geometries. M^3 is designed for modeling nebulae in arbitrary three-dimensional geometries. In this paper, we describe the Monte-Carlo radiative transfer technique and the microphysics implemented in M^3, including the photoionization, collisional ionization, the free-free and free-bound recombination, and two-photon radiation. We put M^3 through the Lexington/Meudon benchmarks to test the reliability of the new code. We apply M^3 to three HII region models with fiducial geometries, demonstrating that M^3 is capable of dealing with nebulae with complex geometries. M^3 is a promising tool for understanding emission-line behavior in the era of SDSS-V/LVM and JWST, which will provide high-quality data of spatially-resolved nearby HII regions and highly turbulent local and high-redshift HII regions.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The exchange of a pair of neutrinos between two objects, seperated by a distance $r$, leads to a long-range effective potential proportional to $1/r_{}^5$, assuming massless neutrinos and four-fermion contact interactions. In this paper, we investigate how this known form of neutrino-mediated potentials might be altered if the distance $r$ is sufficiently short, corresponding to a sufficiently large momentum transfer which could invalidate the contact interactions. We consider two possible scenarios to open up the contact interactions by introducing a $t$-channel or an $s$-channel mediator. We derive a general formula that is valid to describe the potential in all regimes as long as the external particles remain non-relativistic. In both scenarios, the potential decreases as $1/r_{}^5$ in the long-range limit as expected. In the short-range limit, the $t$-channel potential exhibits the Coulomb-like behavior (i.e. proportional to $1/r$), while the $s$-channel potential exhibits $1/r_{}^4$ and $1/r_{}^2$ behaviors.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We show that the gravitational wave signals from primordial black hole (PBH) binaries at high redshift can be detected. The detectability of PBH binaries is enhanced by redshift bias and more PBH binaries at high redshift. The initial clustering of PBHs is also included and enhances the effectively detectable mass ranges of PBHs at high redshift. Future observations on the gravitational wave at high redshift by space-based detectors such as LISA and SKA can constrain the fraction of PBHs in dark matter and PBHs initial distribution.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Inverse mass cascade is a key feature of statistically steady state for self-gravitating collisionless dark matter flow (SG-CFD). Continuous mass transfer from small to large mass scales (inverse) is formulated. Direct effect of mass cascade on halo mass function is presented. Mass cascade is local, two-way, and asymmetric in mass space. Halos inherit/pass their mass from/to halos of similar size. Two regimes are identified: a propagation range with scale-independent rate of mass transfer and a deposition range with cascaded mass consumed to grow halos. Dimensional analysis leads to a power-law mass function in propagation range with a geometry exponent ${\lambda}$. A fundamental merging frequency $f_0{\sim}m_p^{\lambda-1}a^{-1}$ is identified, where $a$ is scale factor. Particle mass $m_p$ can be determined if that frequency is known. Rate of mass transfer ${\epsilon}_m{\sim}a^{-1}$ is independent of halo mass, a key feature of propagation range. Typical halos grow as $m_h{\sim}a^{3/2}$ and halo lifespan scales as ${\sim}m_h^{-\lambda}$. Chain reaction of mass cascade provides non-equilibrium dark matter flow a mechanism to continuously release energy and maximize entropy. Continuous injection of mass ("free radicals") at the smallest scale is required to sustain the everlasting inverse mass cascade such that total halo mass $M_h$ increases as $a^{1/2}$. These "radicals" might be directly generated at the smallest Planck scale or by a direct cascade from large to small scales. Entire mass cascade can be formulated by random walk in mass space, where halos migrate with an exponential distribution of waiting time. This results in a heterogeneous diffusion model, where Press-Schechter mass function can be fully derived without relying on any specific collapse models. A double-$\lambda$ mass function is proposed with different $\lambda$ for two ranges and agrees with N-body simulations.
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