Do Minor Interactions Trigger Star Formation in Galaxy Pairs?

We analyze the galaxy pairs in a set of volume limited samples from the Sloan Digital Sky Survey to study the effects of minor interactions on the star formation rate(SFR)and color of galaxies.We carefully design control samples of isolated galaxies by matching the stellar mass and redshift of the minor pairs.The SFR distributions and color distributions in the minor pairs differ from their controls at>99%significance level.We also simultaneously match the control galaxies in stellar mass,redshift and local density to assess the role of the environment.The null hypothesis can be rejected at>99%confidence level even after matching the environment.Our analysis shows a quenching in the minor pairs where the degree of quenching decreases with the increasing pair separation and plateaus beyond 50 kpc.We also prepare a sample of minor pairs with Hαline information.We calculate the SFR of these galaxies using the Hαline and repeat our analysis.We observe a quenching in the Hαsample too.We find that the majority of the minor pairs are quiescent systems that could be quenched due to minor interactions.Combining data from the Galaxy Zoo and Galaxy Zoo 2,we find that only∼1%galaxies have a dominant bulge,4%–7%galaxies host a bar and 5%–10%of galaxies show active galactic nucleus(AGN)activity in minor pairs.This indicates that the presence of bulge,bar or AGN activity plays an insignificant role in quenching the galaxies in minor pairs.The more massive companion satisfies the criteria for mass quenching in most of the minor pairs.We propose that the stripping and starvation likely caused the quenching in the less massive companion at a later stage of evolution.

Determination of Distance,Extinction,Mass,and Age for Stars in LAMOST DR7

Large scale spectroscopic surveys such as that using Large-sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) have collected spectra of millions stars in the Milky Way.Utilizing this huge sample of stars to study the assembling history and structure of our Galaxy requires accurate estimates of distance,extinction,age,and mass for individual stars.Combining the parallax constraint from Gaia EDR3 with Bayesian inference,we have estimated the distance and extinction for stars observed in LAMOST DR7,as well as the stellar mass and age for evolved stars in this data release.We validated the accuracies of the stellar parameters by comparing our results against various measurements,including the star-pair technique,asteroseismology,globular clusters,and isochrone fits to main sequence stars and subgiants.This is a valuable catalog of stellar parameters under a Bayesian framework estimated using the data from Gaia EDR3 and LAMOST spectroscopic data.With this data set we explored the stellar population of the Galactic massive substructure Gaia-Sausage-Enceladus(GSE).The kinematically selected members of GSE have a median metallicity of [Fe/H] =-1.29 and a median age of 11.6 Gyr.

我国护理信息化发展现状及其局限性思考

从临床护理、护理管理、护理教育方面概述了我国护理信息化的发展现状,并对护理信息化存在的局限性进行分析,提出相关策略。

块体Pd_(82)Si_(18)非晶合金的制备及晶化行为研究

采用玻璃包覆 +水淬技术制备了块体Pd82 Si1 8非晶合金 .实验结果表明 ,净化对该熔体的非晶形成能力有很大的影响 .通过对深过冷Pd82 Si1 8合金的凝固行为研究发现 ,当过冷度大于 1 90K时 ,过冷熔体会出现液相分离现象 ,热力学分析表明这将降低该过冷熔体的非晶形成能力 .该非晶的晶化实验结果显示 ,与旋铸法制备的Pd82 Si1 8非晶条带不同 ,块体非晶的晶化过程中出现两个放热峰 ,同时玻璃转变温度、晶化温度、过冷液相区都有相应的变化 .通过分析可知Pd82 Si1

A Study of Binary Stellar Population Synthesis of Elliptical Galaxies

We determined the relative stellar ages and metallicities of about 80 elliptical galaxies in both low and high density environments using the latest binary stellar population （BSP） synthesis model and tested the predictions of a recent hierarchical formation model that adopted the new ACDM cosmology. The stellar ages and metallicities were estimated from two high-quality published spectra line indices, the Hβ and [MgFe] indices. The results show that the stellar populations of elliptical galaxies are older than 3.9 Gyr and more metal rich than 0.02. Most of our results are in agreement with the model predictions; （1） elliptical galaxies in denser environment are redder and have older populations than field galaxies; （2） elliptical galaxies with more massive stellar components are redder and have older and more metal rich populations than less massive ones; （3） the most massive galaxies have the oldest and most metal rich stars. However, some of our results differ from the model predictions on the metallicity distributions of low- and high-density elliptical galaxies and the dependence on the distance to the cluster center.

Numerical simulation of a possible origin of the positive radial metallicity gradient of the thick disk

We analyze the radial and vertical metallicity and [α/Fe] gradients of the disk stars of a disk galaxy simulated in a fully cosmological setting with the chemo- dynamical galaxy evolution code GCD＋. We study how the radial abundance gradients vary as a function of height above the plane and find that the metallicity （[α/Fe]） gra- dient becomes more positive （negative） with increasing height, changing sign around 1.5 kpc above the plane. At the largest vertical height （2 〈 丨z丨 〈 3 kpc）, our simulated galaxy shows a positive radial metallicity gradient. We find that the positive metallicity gradient is caused by the age-metallicity and age-velocity dispersion relation, where younger stars have higher metallicity and lower velocity dispersion. Due to the age- velocity dispersion relation, a greater fraction of younger stars reaches 丨z丨 〉 2 kpc at the outer region, because of the lower gravitational restoring force of the disk, i.e. flaring. As a result, the fraction of younger stars with higher metallicity due to the age-metallicity relation becomes higher at the outer radii, which makes the median metallicity higher at the outer radii. Combining this result with the recently observed age-metallicity and age-velocity dispersion relation for the Milky Way thick disk stars suggested by Haywood et al., we argue that the observed （small） positive radial metal- licity gradient at large heights of the Milky Way disk stars can be explained by flaring of the younger thick and/or thin disk stars.

Collapsing index:a new method to identify star-forming cores based on ALMA images

Stars form through the gravitational collapse of molecular cloud cores.Before collapsing,the cores are supported by thermal pressure and turbulent motions.A question of critical importance for the understanding of star formation is how to observationally discern whether a core has already initiated gravitational collapse or is still in hydrostatic balance.The canonical method to identify gravitational collapse is based on the observed radial density profile,which would change from Bonnor-Ebert type toward power laws as the core collapses.In practice,due to the projection effect,the resolution limit and other caveats,it has been difficult to directly reveal the dynamical status of cores,particularly in massive star forming regions.We here propose a novel,straightforward diagnostic,namely,the collapsing index(CI),which can be modeled and calculated based on the radial profile of the line width of dense gas.A meaningful measurement of CI requires spatially and spectrally resolved images of optically thin and chemically stable dense gas tracers.ALMA observations are making such data sets increasingly available for massive star forming regions.Applying our method to one of the deepest dense-gas spectral images ever taken toward such a region,namely,the Orion molecular cloud,we detect the dynamical status of selected cores.We observationally distinguished a collapsing core in a massive star forming region from a hydrostatical one.Our approach would help significantly improve our understanding of the interaction between gravity and turbulence within molecular cloud cores in the process of star formation.

Molecular Cores in Different Evolutionary Stages near Luminous IRAS Sources and UC HII Regions

We report the results of ^12CO of Ultra-Compact （UC） HII regions with and ^13CO J=1-0 observations of eight candidates the Purple Mountain Observatory （PMO） Qinghai 13.7 -m telescope, which resulted in revealing 11 molecular cores. Their masses range from 130 to 1.7 × 10^4 M⊙, with different spatial scales （1 - 6 pc）. Also presented are the relevant HCO＋ j=1-0 maps, which enabled us to investigate more detailed structures of these cores. Further comparisons show that four of the cores deviated from the centers of infrared （MIR） emission of Midcourse Space Experiment （MSX）, while others correspond either to bright MIR sources or diffuse MIR background. This indicates various evolutionary phases of the cores, including quite early ones for those without MIR sources.

Made-to-measure galaxy modelling utilising absorption line strength data

We enhance the Syer ＆ Tremaine made-to-measure （M2M） particle method of stellar dynamical modelling to model simultaneously both kinematic data and absorption line strength data, thus creating a ＇chemo-M2M＇ modelling scheme. We apply the enhanced method to four galaxies （NGC 1248, NGC 3838, NGC 4452, NGC 4551） observed using the SAURON integral-field spectrograph as part of the ATLAS3D programme. We are able to reproduce successfully the 2D line strength data achieving mean X2 per bin values of ≈ 1 with 〉 95% of particles having converged weights. Because M2M uses a 3D particle system, we are also able to examine the underlying 3D line strength distributions. The extent to which these dis- tributions are plausible representations of real galaxies requires further consideration. Overall, we consider the modelling exercise to be a promising first step in developing a ＇chemo-M2M＇ modelling system and in understanding some of the issues to be addressed. While the made-to-measure techniques developed have been applied to absorption line strength data, they are in fact general and may be of value in modelling other aspects of galaxies.

What is the right way to quench star formation in semi-analytic models of galaxy formation?

Semi-analytic models of galaxy formation are powerful tools to study the evolution of a galaxy population in a cosmological context. However, most models overpredict the number of low- mass galaxies at high redshifts and the colors of model galaxies are not right in the sense that low-mass satellite galaxies are too red and centrals are too blue. The recent version of the L-Galaxies model by Henriques et al. （H15） is a step forward to solve these problems by reproducing the evolution of stellar mass function and the overall fraction of red galaxies. In this paper we compare the two model predictions of L-Galaxies （the other is Guo et al., G13） to SDSS data in detail. We find that in the H15 model the red fraction of central galaxies now agrees with the data due to their implementation of strong AGN feedback, but the stellar mass of centrals in massive halos is now slightly lower than what is indicated by the data. For satellite galaxies, the red fraction of low-mass galaxies （log M./M~ 〈 10） also agrees with the data, but the color of massive satellites （10 〈 logM,/M~ 〈 11） is slightly bluer. The correct color of centrals and the bluer color of massive satellites indicate that quenching in massive satellites is not strong enough. We also find that there are too many red spirals and less bulge-dominated galaxies in both H15 and G13 models. Our results suggest that additional mechanisms, such as more minor mergers or disk instability, are needed to slightly increase the stellar mass of the central galaxy in massive galaxies, mainly in the bulge component, and bulge dominated galaxies will be quenched not only by minor mergers, but also by some other mechanisms.

HNCO： a molecule that traces low-velocity shocks

Using data from Millimetre Astronomy Legacy Team Survey at 90 GHz （MALT90）, we present a molecular line study of a sample of APEX Telescope Large Area Survey of the Galaxy （ATLASGAL） clumps. Twelve emission lines have been detected in all. We found that in most sources, emissions of HC3N, HN13C, CH3CN, HNCO and SiO show more compact distributions than those of HCO＋, HNC, HCN and N2H＋. By comparing with other molecular lines, we found that the abun- dance of HNCO （x（HNCO）） correlates well with other species such as HC3N, HNC, C2H, H13CO＋ and N2H＋. Previous studies indicate the HNCO abundance could be enhanced by shocks. However, in this study, we find the abundance of HNCO does not correlate well with that of SiO, which is also a good tracer of shocks. We suggest this may be because HNCO and SiO trace different parts of shocks. Our analysis indicates that the velocity of a shock traced by HNCO tends to be lower than that traced by SiO. In the low-velocity shocks traced by HNCO, the HNCO abundance increases faster than that of SiO. While in the relatively high-velocity shocks traced by SiO, the SiO abundance increases faster than that of HNCO. We suggest that in the infrared dark cloud MSXDC G331.71＋00.59, high-velocity shocks are destroying the molecule HNCO.

A Study of Star Formation in BRC18

Using the 13.7m radio telescope at Delingha, the millimeter-wave radioobservatory of Purple Mountain Observatory, we made mapping observations in ^(12)CO J = 1 - 0 linetowards IRAS 05417+0907, located in the bright-rimmed cloud (BRC) BRC18. We used a 7 x 7 grid with1' spacing, a finer and larger grid than the one used by Myers et al. Our results show that there isa bipolar outflow near IRAS 05417+0907. Combining with the observations at other wave bands, wefind that the star formation process in this region is triggered by radiation-driven implosion. Thesignificant difference between the masses of BRC18 and the cores and the relatively large ratio ofassociated source bolometric luminosity to the mass show that the star formation in BRC18 may betaking place in a sequence.

增强高师院校计算机文化基础教学的实效性

结合阜阳师院公共计算机文化基础课教学的实际情况,从适应教师教育信息化建设的要求出发,以培养高信息素质的末来教师为目标,对如何增强高师院校计算机文化基础教学的实效性进行了初步的探讨。

企业信息化平台的构建与精细化管理

企业信息化建设如果不能解决信息平台上各系统相对独立的信息孤岛问题,决策层和管理层便不能有效、快捷地获取生产经营管理的实时数据信息,影响决策和管理的准确性与时效性。通过运用科学的决策和分析方法,建立全息化"生产经营分析与预测体系",是提升企业精细化管理水平的有效手段,企业实践也已证明其对经营管理具有极大的推动作用。阐述整体信息化架构和全息化生产经营分析与预测体系的构建、实施方法和取得的效果。

公安基层应用视频侦查技术的现状及展望

"四侦一化"是现代刑事案件侦破的重要技术支撑,其中视频侦查技术应用越来越广泛。视频侦查技术具有特殊的应用价值,发挥着重要的作用。当前基层公安视频侦查工作仍存在一些问题。未来需要关注人脸识别、视频结构化、异常行为分析、数据挖掘、深度学习模型、人工智能等六个方面技术的应用。

以信息化带动工业化的着力点与政策整合

"以信息化带动工业化"内涵三层要求:实现信息化与工业化重合并进、以信息化赋予工业化现代的内涵、以信息化推进、加快工业化进程。"以信息化带动工业化"应以大力发展信息产业、利用信息技术,提升传统产业、加强信息基础设施建设为着力点。同时综合运用产业政策、税收政策、投资政策,实现信息化带动工业化的政策整合。

Cs-Mg-H合金的形成能力与成键机制研究

采用基于密度泛函理论第一性原理的Vienna Abinitio Simulation Package(VASP)软件研究了CsMgH3,Cs4Mg3H10和Cs2MgH4氢化物的晶体结构、反应焓和电子结构.结果表明CsMgH3,Cs4Mg3H10和Cs2MgH4都能直接由单质Cs和Mg在H2中反应生成,其中Cs4Mg3H10的形成能力最强;态密度和电荷密度的分析与讨论表明了Mg和H的成键机制为离子键伴随着显著的共价键.

信息产业化与产业信息化互动研究

通过分析不同产业之间的各自所需,建立相应的产业互动模型,从而实现产业共同升级的目的,同时也使信息产业化和产业信息化的目标得以实现。