分类： 医学、药学 >> 临床医学 提交时间： 2024-07-29 合作期刊: 《中国全科医学》
摘要： 背景根据中医藏象学说中“肺与大肠相表里”理论，前期研究发现自拟中药清肺化瘀通腑方对脓毒症相关急性呼吸窘迫综合征（ARDS）具有积极治疗作用，但目前关于清肺化瘀通腑方治疗时机对脓毒症相关 ARDS患者临床疗效及预后影响的研究较少。目的 探索中药方剂清肺化瘀通腑方治疗脓毒症相关 ARDS 的最佳切入时机及其对治疗效果和预后的影响。方法 回顾性选择 2021—2023 年江苏省中医院重症医学科诊断为脓毒症相关 ARDS 且治疗过程中联合中药汤剂清肺化瘀通腑方治疗的 208 例患者。按照中药首次使用时间，确诊脓毒症相关 ARDS 48 h 内（包括 48 h）开始服用清肺化瘀通腑方患者为早期干预组；48 h 后开始服用清肺化瘀通腑方患者为晚期干预组。最终早期干预组 109 例，晚期干预组 85 例，失访患者 14 例。比较两组患者的临床疗效及预后。结果 早期干预组 28 d 全因病死率为 13.8%，低于晚期干预组的 29.4%（P=0.0014），且晚期干预组死亡风险为早期干预组的 2.11 倍（HR=2.11，95%CI=1.13~3.91，P=0.019）。早期干预组机械通气天数中位数为 12（8，23）d，少于晚期干预组的 27（13，35）d（P=0.035）。两组组内对比，治疗后氧合指数均较治疗前有所改善（P<0.001），C 反应蛋白、降钙素原、白细胞与本组治疗前比较均下降（P<0.05）。两组治疗后早期干预组氧合指数均数为（319.87±95.32），大于晚期干预组的（259.55±99.72）（P<0.001）。两组治疗后早期干预组 C 反应蛋白中位数为 19.39（8.16，44.47） mg/L，低于晚期干预组的 38.01（17.53，86.05） mg/L（P<0.001）。两组治疗后早期干预组降钙素原中位数为 0.175（0.089，0.75） ng/mL，低于晚期干预组的0.46（0.143，1.85） ng/mL（P=0.004）。结论 早期（确诊后 48 h 内）合理给予中药治疗脓毒症相关 ARDS 可减少患者 28 d 全因病死率及机械通气天数，改善患者氧合指数，减轻炎性反应。
分类： 医学、药学 >> 预防医学与公共卫生学 提交时间： 2024-07-29 合作期刊: 《中国全科医学》
摘要： 全科医生的定位是社区的健康守门人，对签约及辖区内居民的健康情况有全面和持续的了解。全科医生不但需要有处理常见疾病的能力，也需要有识别和管理非常见疾病的能力。对于非常见疾病，全科医生面临两种挑战：一是部分非常见疾病的临床症状无特异性，当同时伴随基础疾病时，容易被社区全科医师漏诊。二是，罹患非常见疾病患者在上级医院诊治后回到社区时，全科医生对此类疾病知之甚少，缺乏综合管理的能力。作为全科医生，应该学会从生物、心理、社会、家庭等多种层面综合评估患者，促进疾病诊治及管理更加完善和全面。本文通过一例罕见的原发中枢神经系统淋巴瘤病例，该患者起病隐匿，通过全科医学科主导的多科室联合诊疗，经过手术、术后康复、疼痛管理和营养评定等逐渐好转，并制定家庭管理和后续治疗策略后离院，分享全科医学科通过“全专结合”管理非常见疾病的经验，以提升全科医生综合管理能力。
分类： 医学、药学 >> 临床医学 提交时间： 2024-07-29 合作期刊: 《中国全科医学》
摘要： 背景卡瑞利珠单抗是我国自主研发的一种 PD-1 抑制剂，目前已在食管癌治疗中获批适应证，但其在临床实践中的有效性及安全性数据仍旧缺乏。目的评估基于卡瑞利珠单抗的方案在真实世界中治疗局部晚期及转移性食管癌的有效性和安全性；探索在不同的治疗背 景下，反应性毛细血管增生症（reactive cutaneous capillary endothelial proliferation，RCCEP）能否预测卡瑞利珠单抗的疗效。方法回顾性收集 2019-11-01 至 2022-05-31 于河北医科大学第四医院接受卡瑞利珠单抗治疗的局部晚期及转移性食管癌患者临床资料。评估无进展生存期（PFS）、总生存期（OS）、客观缓解率（ORR）、疾病控制率（DCR）和不良反应发生情况。比较 RCCEP 组患者和无 RCCEP组患者的生存函数。结果在纳入研究的 70 例局部晚期及转移性食管癌患者中，疗效评价为完全缓解（CR）11 例（15.7%），部分缓解（PR）35 例（50.0%），疾病稳定（SD）17 例（24.3%），疾病进展（PD）7 例（10%），ORR65.7%（46/70），DCR 90.0%（63/70）。其中，接受一线至三线治疗的 47 例患者的中位 PFS 为 8.1 个月（95%CI=6.46~9.74个月），1 年 PFS 率为 34.0%；中位 OS 未达到，1 年 OS 率为 76.3%。接受新辅助治疗的 23 例患者均都达到 R0 切除，6 例患者达到病理完全缓解（pCR）（26.1%）。RCCEP（65.7%）、恶心 / 呕吐（42.8%）、贫血（37.1%）、乏力（37.1%）和脱发（34.2%）是常见的不良反应类型。≥ 3 级的不良反应发生率为 21.4%（15/70），主要为白细胞计数减低（5.7%）、中性粒细胞计数减低（5.7%）以及血小板计数减低（4.3%）。4 例患者发生了≥ 3 级的免疫相关不良反应，包括 3 级心肌炎 1 例，3 级肺炎 1 例，3 级皮疹 1 例以及 4 级肾炎 1 例。所有患者经对症和（或）糖皮质激素治疗后均得到缓解，没有发生治疗相关的死亡。RCCEP 与卡瑞利珠单抗的疗效相关，RCCEP 组患者的 ORR（76.1% vs 45.8%，P=0.01）和DCR（97.8% vs 75.0%，P=0.009）高于无 RCCEP 组患者，RCCEP 组患者较无 RCCEP 组患者的中位 PFS（18 个月 vs 7.4个月，P=0.015）及 OS（未达到 vs 15.7 个月，P=0.000）显著延长。结论在真实世界中，基于卡瑞利珠单抗的治疗方案能够为局部晚期及转移性食管癌患者带来一定的生存获益，不良反应可耐受；在不同的治疗背景下，RCCEP 能够预测卡瑞利珠单抗的疗效。
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： 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 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： 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： Measuring the Cosmic X-ray Background (CXB) is a key to understand the Active Galactic Nuclei population, their absorption distribution and their average spectra. However, hard X-ray instruments suffer from time-dependent backgrounds and cross-calibration issues. The uncertainty of the CXB normalization remain of the order of 20%. To obtain a more accurate measurement, the Monitor Vsego Neba (MVN) instrument was built in Russia but not yet launched to the ISS (arXiv:1410.3284). We follow the same ideas to develop a CXB detector made of four collimated spectrometers with a rotating obturator on top. The collimators block off-axis photons below 100 keV and the obturator modulates on-axis photons allowing to separate the CXB from the instrumental background. Our spectrometers are made of 20 mm thick CeBr$_{3}$ crystals on top of a SiPM array. One tube features a $\sim$20 cm$^2$ effective area and more energy coverage than MVN, leading to a CXB count rate improved by a factor of $\sim$10 and a statistical uncertainty $\sim$0.5% on the CXB flux. A prototype is being built and we are seeking for a launch opportunity.
分类： 医学、药学 >> 预防医学与公共卫生学 提交时间： 2024-07-29 合作期刊: 《中国全科医学》
摘要： 背景我国经济与卫生事业协同作用随着发展逐渐凸显。基层卫生健康工作是保障人民群众健康的最前线，而提升基层医疗卫生服务能力是我国十四五时期乃至今后卫生事业的主要任务。2015—2020 年宁夏农村经济保持快速增长态势，对基层医疗卫生机构的投入力度不断加大。目的 研究宁夏基层医疗服务能力与区域经济发展的耦合协调及空间分布，并探索其驱动力。方法 通过构建宁夏基层医疗服务能力和区域经济发展评价指标体系，采用熵值法、耦合协调模型、地理探测器等对 2015—2020 年宁夏 22 个县（区）203 个乡镇卫生院服务能力与区域经济发展之间的协调性进行研究。结果宁夏区域经济综合评价指数高于基层医疗服务能力综合评价指数；两子系统的耦合协调度在时间序列上呈现上升态势，在空间布局上呈由南向北逐渐下降的分布格局；卫生资源、医疗服务量等因子成为驱动两系统协调发展的重要因子，区域经济因子逐渐弱化。结论宁夏基层医疗服务能力与区域经济的耦合协调度有较大的提升空间，区域间差异显著，需从加大卫生投入、强化医防融合等方面持续提升基层医疗服务能力；以区域经济高质量发展为着力点，逐步强化基层医疗服务水平，推动两系统协同发展。
分类： 医学、药学 >> 预防医学与公共卫生学 提交时间： 2024-07-29 合作期刊: 《中国全科医学》
摘要： 社区康复与基本公共卫生服务有着许多共通之处。基层医疗卫生机构在为辖区居民做好基本公共卫生服务的同时，若能将康复服务精准对接至有需求的人群，减轻其功能障碍程度，提升其生活质量，实现“康复在基层”的功能定位，将具有重要意义。本文聚焦社区康复与基本公共卫生服务协同发展的对策思考，提出基层机构在服务提供上可推进个体健康管理与临床康复无缝衔接，在服务协作上可建立全科医生模式下的社区康复、组建“康复 - 公卫”联盟、制订个性化家医签约服务包等协作机制，在服务筹资上可充分探讨现有筹资来源的整合支付，以期为基层机构康复职能的拓展提供参考，助力实现全人群健康水平持续提升、国民医疗经济负担持续降低的长远目标。
分类： 医学、药学 >> 预防医学与公共卫生学 提交时间： 2024-07-29 合作期刊: 《中国全科医学》
摘要： 背景高血压作为危险因素能够显著增加城乡居民心脑血管疾病的发病率与死亡率，有效控制高血压是防治心脑血管疾病的重中之重。目的全面收集我国不同高血压管理模式效果评价方面的文献，评价不同模式的管理效果，为进一步优化高血压管理模式提供参考依据。方法 使用统计软件 StataSE-64，以血压控制率为评价指标，对纳入的 18 篇高血压管理模式文献涉及医院 - 社区联合管理、常规社区管理、常规医院治疗管理、一般管理、“互联网＋”管理五种模式进行网状 Meta 分析。结果 相对于作为空白对照的一般管理模式，医院 - 社区联合管理、常规社区管理、常规医院管理、“互联网＋”管理四种模式对高血压控制都具有一定效果。总体效果排序为医院 - 社区联合管理≈“互联网＋”管理 > 常规医院治疗管理 > 常规社区管理 > 空白对照。其中医院 - 社区联合管理模式对高血压控制效果显著；医院 - 社区联合管理模式与“互联网 +”管理模式效果相近；常规医院管理比常规社区管理效果好。结论为完善基层高血压管理模式，应推进基层医疗卫生机构医院 - 社区 - 家庭管理模式建设，引导慢性病管理模式与“互联网 + 医疗”模式结合，加强慢性病全生命全周期管理。
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Salvatore Ferrone
Paola Di Matteo
Alessandra Mastrobuono-Battisti
Misha Haywood
Owain N. Snaith
Marco Montouri
Sergey Khoperskov
David Valls-Gabaud
摘要： We present the e-TidalGCs Project which aims at modeling and predicting the extra-tidal features surrounding all Galactic globular clusters for which 6D phase space information, masses and sizes are available (currently 159 globular clusters). We focus the analysis and presentation of the results on the distribution of extra-tidal material on the sky, and on the different structures found at different heliocentric distances. We emphasize the wide variety of morphologies found: beyond the canonical tidal tails, our models reveal that the extra-tidal features generated by globular clusters take a wide variety of shapes, from thin and elongated shapes, to thick, and complex halo-like structures. We also compare some of the most well studied stellar streams found around Galactic globular clusters to our model predictions, namely those associated to the clusters NGC 3201, NGC 4590, NGC 5466 and Pal 5. Additionally, we investigate how the distribution and extension in the sky of the simulated streams vary with the Galactic potential by making use of three different models, containing or not a central spheroid, or a stellar bar. Overall, our models predict that the mass lost by the current globular cluster population in the field from the last 5 Gyrs is between $0.3-2.1\times10^{7}M_{\odot}$, an amount comparable between 7-55 % of current mass. Most of this lost mass is found in the inner Galaxy, with the half-mass radius of this population being between 4-6 kpc. The outputs of the simulations will be publicly available, at a time when the ESA Gaia mission and complementary spectroscopic surveys are delivering exquisite data to which these models can be compared.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Dark radiation (DR) is generally predicted in new physics scenarios that address fundamental puzzles of the Standard Model or tensions in the cosmological data. Cosmological data has the sensitivity to constrain not only the energy density of DR, but also whether it is interacting. In this paper, we present a systematic study of five types of interacting DR (free-streaming, fluid, decoupling, instantaneous decoupling, and recoupling DR) and their impact on cosmological observables. We modify the Boltzmann hierarchy to describe all these types of interacting DR under the relaxation time approximation. We, for the first time, robustly calculate the collision terms for recoupling scalar DR and provide a better estimation of the recoupling transition redshift. We demonstrate the distinct features of each type of DR on the CMB and matter power spectra. We perform MCMC scans using the Planck 2018 data and BAO data. Assuming no new physics in the SM neutrino sector, we find no statistically significant constraints on the couplings of DR, although there is a slight preference for a late transition redshift for instantaneous decoupling DR around recombination, and for the fluid-like limit of all the cases. The $\Delta N_{\rm eff}$ constraint varies marginally depending on the type of DR.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Compact Obscured Nuclei (CONs) account for a significant fraction of the population of luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs). These galaxy nuclei are compact, with radii of 10-100~pc, with large optical depths at submm and far-infrared wavelengths, and characterized by vibrationally excited HCN emission. It is not known what powers the large luminosities of the CON host galaxies because of the extreme optical depths towards their nuclei. CONs represent an extreme phase of nuclear growth, hiding either a rapidly accreting supermassive black hole or an abnormal mode of star formation. Here we apply principal component analysis (PCA) tomography to high-resolution (0.06$^{\prime\prime}$) ALMA observations at frequencies 245 to 265~GHz of the nearby CON (59~Mpc) IC~860. PCA is a technique to unveil correlation in the data parameter space, and we apply it to explore the morphological and chemical properties of species in our dataset. The leading principal components reveal morphological features in molecular emission that suggest a rotating, infalling disk or envelope, and an outflow analogous to those seen in Galactic protostars. One particular molecule of astrochemical interest is methanimine (CH$_2$NH), a precursor to glycine, three transitions of which have been detected towards IC 860. We estimate the average CH$_2$NH column density towards the nucleus of IC~860 to be $\sim10^{17}$cm$^{-2}$, with an abundance exceeding $10^{-8}$ relative to molecular hydrogen, using the rotation diagram method and non-LTE radiative transfer models. This CH$_2$NH abundance is consistent with those found in hot cores of molecular clouds in the Milky Way. Our analysis suggests that CONs are an important stage of chemical evolution in galaxies, that are chemically and morphologically similar to Milky Way hot cores.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Christopher J. White
Patrick D. Mullen
Yan-Fei Jiang
Shane W. Davis
James M. Stone
Viktoriya Morozova
Lizhong Zhang
摘要： We extend the general-relativistic magnetohydrodynamics (GRMHD) capabilities of Athena++ to incorporate radiation. The intensity field in each finite-volume cell is discretized in angle, with explicit transport in both space and angle properly accounting for the effects of gravity on null geodesics, and with matter and radiation coupled in a locally implicit fashion. Here we describe the numerical procedure in detail, verifying its correctness with a suite of tests. Motivated in particular by black hole accretion in the high-accretion-rate, thin-disk regime, we demonstrate the application of the method to this problem. With excellent scaling on flagship computing clusters, the port of the algorithm to the GPU-enabled AthenaK code now allows the simulation of many previously intractable radiation-GRMHD systems.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： Supernova (SN) cosmology is based on the assumption that the width-luminosity relation (WLR) and the color-luminosity relation (CLR) in the type Ia SN luminosity standardization would not show {absolute magnitude differences} with progenitor age. Unlike this expectation, recent age datings of stellar populations in host galaxies have shown significant correlations between progenitor age and Hubble residual (HR). Here we show that this correlation originates from a strong progenitor age dependence of the zero-points of the WLR and the CLR, in the sense that SNe from younger progenitors are fainter each at given light-curve parameters $x_1$ and $c$. This $4.6\sigma$ result is reminiscent of Baade's discovery of the zero-point variation of the Cepheid period-luminosity relation with age, and, as such, causes a serious systematic bias with redshift in SN cosmology. Other host properties show substantially smaller and insignificant offsets in the WLR and CLR for the same dataset. We illustrate that the differences between the high-$z$ and low-$z$ SNe in the WLR and CLR, and in HR after the standardization, are fully comparable to those between the correspondingly young and old SNe at intermediate redshift, indicating that the observed dimming of SNe with redshift may well be an artifact of over-correction in the luminosity standardization. When this systematic bias with redshift is properly taken into account, there is little evidence left for an accelerating universe, in discordance with other probes, urging the follow-up investigations with larger samples at different redshift bins.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We develop a framework for using clustering-based redshift inference (cluster-$z$) to measure the evolving galaxy luminosity function (GLF) and galaxy stellar mass function (GSMF) using WISE W1 ($3.4\mu m$) mid-infrared photometry and positions. We use multiple reference sets from the Galaxy And Mass Assembly (GAMA) survey, Sloan Digital Sky Survey (SDSS) and Baryon Oscillation Spectroscopic Survey (BOSS). Combining the resulting cluster-$z$s allows us to enlarge the study area, and by accounting for the specific properties of each reference set, making best use of each reference set to produce the best overall result. Thus we are able to measure the GLF and GSMF over $\sim 7500\, \mathrm{deg}^2 $ of the Northern Galactic Cap (NGC) up to $z<0.6$. Our method can easily be adapted for new studies with fainter magnitudes, which pose difficulties for the derivation of photo-$z$s. The measurement of the GSMF is currently limited by the models for k-corrections and mass-to-light ratios, rather than more complicated effects tied to the evolution of the differential galaxy bias. With better statistics in future surveys this technique is a strong candidate for studies with new emerging data from, e.g. the Vera C. Rubin Observatory, the Euclid mission or the Nancy Grace Roman Space Telescope.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The dynamics of magnetic reconnection in the solar current sheet (CS) is studied by high-resolution 2.5-dimensional MHD simulation. With the commence of magnetic reconnection, a number of magnetic islands are formed intermittently and move quickly upward and downward along the CS. When colliding with the semi-closed flux of flare loops, the downflow islands cause a second reconnection with a rate even comparable with that in the main CS. Though the time-integrated magnetic energy release is still dominated by the reconnection in main CS, the second reconnection can release substantial magnetic energy, annihilating the main islands and generating secondary islands with various scales at the flare loop top. The distribution function of the flux of the second islands is found to follow a power-law varying from $f\left(\psi\right)\sim\psi^{-1}$ (small scale) to $\psi^{-2}$ (large scale), which seems to be independent with background plasma $\beta$ and if including thermal conduction. However, the spatial scale and the strength of the termination shocks driven by main reconnection outflows or islands decrease if $\beta$ increases or thermal conduction is included. We suggest that the annihilation of magnetic islands at the flare loop top, which is not included in the standard flare model, plays a non-negligible role in releasing magnetic energy to heat flare plasma and accelerate particles.
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