分类： 其他 >> 综合 提交时间： 2024-06-13 合作期刊: 《高校图书馆工作》
摘要： “新融合”作为《情报学与情报工作发展南京共识》(简称《南京共识》)中大情报观的重要论点,成为 中国特色情报学学科体系、学术体系及话语体系构建与发展的核心要义,也对情报人才的定位和培养提出了 新的思路与方向。本文旨在突破传统情报人才培养模式,依托全情报能力框架探索构建应用型高层次情报 人才培养新模式。文章采用文献研究、定量与定性相结合、对比及类比等分析方法,对《南京共识》发布前后 国内情报人才培养相关文献进行动态分析研究,再从全情报能力框架出发,结合国内外人才培养先进经验及 政策发展轨迹,总结提炼应用通路,探索构建全情报能力人才培养体系。新融合视域下的全情报能力人才培 养体系着重在课程设置、学科体系、应用领域、关键技术及关联资源等方面实现跨主体、跨时空、跨基础的多 维度合作,以期形成良性反哺效应,在新技术、新思想共同影响下,快速全面发挥全情报能力人才“ 耳目尖兵 参谋”作用。
分类： 其他 >> 综合 提交时间： 2024-06-13 合作期刊: 《高校图书馆工作》
摘要： 针对新文科背景下信息资源管理课程教学效果不佳的问题,将BOPPPS 教学模式引入信息资源管 理的教学中,推动信息资源管理课程教学改革。通过构建基于BOPPPS 的信息资源管理课程教学模式理论框 架,并应用到福州大学信息资源管理课程的具体教学实践中,以信息资源内容管理的信息检索小节为例,详 细阐述了BOPPPS 教学模式在课前、课中及课后的应用。研究发现,采用BOPPPS 教学模式的信息资源管理 课程教学效果较好。文章对基于BOPPPS 的信息资源管理课程教学模式进行反思,提出了完善课程教学的 建议。
分类： 其他 >> 综合 提交时间： 2024-06-13 合作期刊: 《高校图书馆工作》
摘要： 读屏时代传统纸质阅读受到巨大冲击,高校图书馆文献流通率趋于下降,提升文献流通率成为业内 关注的焦点,开展读屏时代高校图书馆文献流通率的研究具有一定的理论和实践价值。文章采用文献研究 法、社会调查法、比较研究法等,深入分析“ 读纸” “ 读屏” 的社会认知以及“ 读屏” 对高校馆藏文献流通的影 响,指出高校图书馆文献流通面临的困境。基于 “读屏”“读纸” 两种阅读方式及其影响,文章指出,“读屏时 代”改变的是阅读载体和读者获取信息的方式,读者对目标信息的需求仍旧不变,“读纸”“读屏”两者可以共 存共融发展。构建文献资源适宜性评价体系、增加文献资源有效供给和合理引导读者需求是“读屏时代” 高 校图书馆提升文献流通率的重要路径。
分类： 其他 >> 综合 提交时间： 2024-06-13 合作期刊: 《高校图书馆工作》
摘要： 在推进全民阅读和乡村文化振兴的当下,鼓励和引导农村居民参与阅读,推进乡村阅读高质量发展 备受业界关注。近年来,政府、社会对农村阅读设施的建设投入和服务力度不断加大。但不可否认的是,农 村阅读设施利用率普遍偏低,农村居民的阅读参与率仍然不高。文章通过调研我国农村公共阅读现状,分析 面临的问题,介绍了浙江省平湖市农民读书会促进乡村阅读发展的个案,从农民读书会的定位、组织架构、具 体做法、产生的社会效益和发展效果评估等多方面阐述,为全国各地推广基层阅读提供经验和借鉴。
分类： 其他 >> 综合 提交时间： 2024-06-13 合作期刊: 《高校图书馆工作》
摘要： 国际图联始终致力于引领和推动全球图书馆事业的发展。2022 年底,《国际图联2021 年度报告》正 式发布,以“图书馆和信息行业的全球声音”为主题,从增强图书馆的全球话语权、引领和加强专业实践、连接 和赋能行业领域、优化组织结构4 个方面总结了国际图联在2021 年的主要贡献。文章通过解析《国际图联 2021 年度报告》的主要内容,为我国图书馆未来发展及更好融入世界舞台提供了相应启示,即:继续强化图书 馆的社会责任、更多体现图书馆服务的专业性、增强图书馆之间的连接、不断提升馆员的技能与优势。
分类： 其他 >> 综合 提交时间： 2024-06-13 合作期刊: 《高校图书馆工作》
摘要： 空间再造是高校图书馆适应用户需求所进行的转型升级。通过网络调研以及问卷调研的方式,以 教育部发布的第一轮42 所“双一流” 高校图书馆为主要研究对象,从空间种类、空间服务功能、空间设备配 置、空间预约形式、空间使用规则、空间开放时间等方面,对“双一流”高校图书馆空间再造的服务现状进行分 析。研究发现目前“双一流”高校图书馆空间再造服务取得了一定的成效,但仍存在宣传推广不足、服务功能 不够丰富、设备配置有待优化、管理制度不够完善等问题。基于用户需求,文章提出加强宣传推广、完善管理 制度、加强服务团队建设、丰富空间服务内容以及注重用户需求与体验等改善策略。
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： Simple climate models have been around for more than a century but have recently come back into fashion: they are useful for explaining global warming and the habitability of extrasolar planets. The Climate App (https://www.climateapp.ca) is an interactive web-based application that describes the radiative transfer governing planetary climate. The App is currently available in French and English and is suitable for teaching high-school through college students, or public outreach. The beginner version can be used to explore the greenhouse effect and planetary albedo, sufficient for explaining anthropogenic climate change, the Faint Young Sun Paradox, the habitability of TRAPPIST planets and other simple scenarios. There is also an advanced option with more atmospheric layers and incorporating the absorption and scattering of shortwave radiation for students and educators wishing a deeper dive into atmospheric radiative transfer. A number of pedagogical activities are being beta tested and rolled out.
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
Baiyang Bi
Miquel Barcelo
Christian Bauer
Faical Ait Benkhali
Jacqueline Catalano
Sebastian Diebold
Christian Föhr
Stefan Funk
Gianluca Giavitto
German Hermann
Jim Hinton
Ira Jung-Richardt
Oleg Kalekin
Ruben Kankanyan
Thomas Kihm
Fabian Leuschner
Marc Pfeifer
Gerd Pühlhofer
Olaf Reimer
Simon Sailer
摘要： In October 2019, the central 28 m telescope of the H.E.S.S. experiment has been upgraded with a new camera. The camera is based on the FlashCam design which has been developed in view of a possible future implementation in the Medium-Sized Telescopes of the Cherenkov Telescope Array (CTA), with emphasis on cost and performance optimization and on reliability. The fully digital design of the trigger and readout system makes it possible to operate the camera at high event rates and to precisely adjust and understand the trigger system. The novel design of the front-end electronics achieves a dynamic range of over 3,000 photoelectrons with only one electronics readout circuit per pixel. Here we report on the performance parameters of the camera obtained during the first year of operation in the field, including operational stability and optimization of calibration algorithms.
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.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We simulate the gravitational dynamics of a massive object interacting with Ultralight / Fuzzy Dark Matter (ULDM/FDM), non-relativistic quantum matter described by the Schrodinger-Poisson equation. We first consider a point mass moving in a uniform background, and then a supermassive black hole (SMBH) moving within a ULDM soliton. After replicating simple dynamical friction scenarios to verify our numerical strategies, we demonstrate that the wake induced by a moving mass in a uniform medium may undergo gravitational collapse that dramatically increases the drag force, albeit in a scenario unlikely to be encountered astrophysically. We broadly confirm simple estimates of dynamical friction timescales for a black hole at the center of a halo but see that a large moving point mass excites coherent "breathing modes" in a ULDM soliton. These can lead to "stone skipping" trajectories for point masses which do not sink uniformly toward the center of the soliton, as well as stochastic motion near the center itself. These effects will add complexity to SMBH-ULDM interactions and to SMBH mergers in a ULDM universe.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： To quantitatively study the driving mechanisms of magnetospheric convection in the magnetotail lobes on a global scale, we utilize data from the ARTEMIS spacecraft in the deep tail and the Cluster spacecraft in the near tail. Previous work demonstrated that, in the lobes near the Moon, we can estimate the convection by utilizing ARTEMIS measurements of lunar ions velocity. In this paper, we analyze these datasets with machine learning models to determine what upstream factors drive the lobe convection in different magnetotail regions and thereby understand the mechanisms that control the dynamics of the tail lobes. Our results show that the correlations between the predicted and test convection velocities for the machine learning models (>0.75) are much better than those of the multiple linear regression model (~ 0.23 - 0.43). The systematic analysis reveals that the IMF and magnetospheric activity play an important role in influencing plasma convection in the global magnetotail lobes.
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