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31.
通过对安徽省A县城乡教师交流政策实施情况的叙事探究,反映出城乡教师交流政策的制定对基层声音聆听不够,政策执行中利益主体各言其妙,政策评价参与主体各有说法,配套政策保障乏力、折扣兑现.只有正视问题,牢记政策目标,把好事做好,才能逐步实现城乡义务教育高水平均衡发展. 相似文献
32.
秦梓华 《中国科技资源导刊》2010,42(2)
农业信息网络建设是农业信息化建设的重点,是解决欠发达地区农业信息获取的关键之一.首先对目前欠发达地区农业信息网络建设现状进行分析,认为缺乏建设农业信息化的内源动力,资金、人才和网络设施等都制约了欠发达地区农业信息网络的建设,不利于农业信息化效果的提高和发展瓶颈的解决.最后提出政府宏观调控下的农村信息合作组织模式可以积极推动欠发达地区农业信息建设和农业科技数据库的建设. 相似文献
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34.
"网络电视风暴"背后--兼论数字新媒体开发制度安排的重要性与紧迫性 总被引：1，自引：0，他引：1
高子华 《中国广播电视学刊》2005,(7):28-29
2004年的岁尾,一场由网络电视激起的新媒体风暴平地起波澜,传统广播电视面对新兴媒体挑战应对无力所暴露的“体制弊端”,引起了业内外的普遍关注。这场“网络电视风暴”再次告诉我们,媒体生态环境已经发生改变,强大竞争对手正在同台竞争。在新媒体产业领域,广播电视已不再享有原先的政策保护和市场垄断优势。因此,与市场接轨的企业制度安排至关重要,否则,我们就会丧失基本竞争力,就不可能占领这一新兴市场,就会失去这一重要的舆论阵地。 相似文献
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对国际乒联施行新竞赛规则带来的变化进行了分析,结果表明：新规则实施后,乒乓球运动的速度、旋转、力量三者的关系发生了质的变化;新规则缩短了比赛进程;增大了比赛胜负的偶然性,提高了比赛的激烈程度;把隐蔽式发球变成了一项“开放性”技术。因此,我国乒乓球技战术指导思想内涵需作相应的调整和补充。 相似文献
36.
高校基层学术组织承担着人才培养、科学研究与社会服务的职能,对于保障人才培养质量意义重大.目前,高校基层学术组织面临权限虚化,职能定位不清,组织过于分化的困境.新形势下,我国高校基层学术组织的变革之路需从自主权重获,加强内涵建设提升人员素质,规范组织构建等方面进行,真正选择契合的并有助于提升人才培养质量的路径. 相似文献
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池子华 《上海师范大学学报(哲学社会科学版)》2015,(3):131-144
申新三厂的福利改革即"劳工事业",最大的亮点就是被誉为"树国内工业界模范"的劳工自治区之设,"凡工人自出生至老死,均已顾及"。从"打工妹"的角度而言,涉及住宿管理、教育设施、医院之设、合作事业、兴建多功能大礼堂等诸多方面。申新三厂的福利改革成效显著:保证了出勤率,在给"打工妹"提供便利的同时,也使工业生产得以正常运转;激发了"打工妹"的积极性,提高了生产效率;增强了企业抵御市场风险的能力;缓和劳资矛盾,改善劳资关系;促进社会风气的改良。但改革也使"打工妹"付出了代价:一些"打工妹"失业而成为改革的"牺牲品";"打工妹"行动自由受限;增加了"打工妹"的经济负担。尽管申新三厂劳工自治区的福利改革存在不尽如人意之处,但成效也显而易见。尤其是在没有政府扶助的情况下,自愿投资建设较为系统的福利设施,组织具有一定民主色彩的劳工自治,这种敢为天下先的精神值得肯定。 相似文献
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Xin Hua Matthew J. Marshall Yijia Xiong Xiang Ma Yufan Zhou Abigail E. Tucker Zihua Zhu Songqin Liu Xiao-Ying Yu 《Biomicrofluidics》2015,9(3)
A vacuum compatible microfluidic reactor, SALVI (System for Analysis at the Liquid Vacuum Interface), was employed for in situ chemical imaging of live biofilms using time-of-flight secondary ion mass spectrometry (ToF-SIMS). Depth profiling by sputtering materials in sequential layers resulted in live biofilm spatial chemical mapping. Two-dimensional (2D) images were reconstructed to report the first three-dimensional images of hydrated biofilm elucidating spatial and chemical heterogeneity. 2D image principal component analysis was conducted among biofilms at different locations in the microchannel. Our approach directly visualized spatial and chemical heterogeneity within the living biofilm by dynamic liquid ToF-SIMS.Mapping how metabolic pathways are interconnected and controlled at the subcellular scale within dynamic living systems continues to present a grand scientific challenge. Biofilms, consisting of aggregations of bacterial cells and extracellular polymeric substance (EPS), present an important avenue for deciphering complex microbial communities. During biofilm formation, cells assemble in a secreted polymer milieu of polysaccharides, proteins, glycolipids, and DNA.1,2 Microfluidics provides unprecedented control over flow conditions, accessibility to real-time observation, high-throughput testing, and mimics in vivo biological environments.3 An understanding of the mechanism underlying biofilm formation and the design of advanced microfluidic experiments could address challenges such as interpreting microbial community interactions, biofouling, and resistance to antimicrobial chemicals. However, only a handful of biofilm studies used microfluidic approaches that provided hydrated chemical imaging at high spatial resolution.4–7 Most studies utilized confocal microscopy,4 FTIR spectroscopy,5 or other approaches (e.g., high density interdigitated capacitors7) for biofilm monitoring. Imaging mass spectrometry has been demonstrated in biofilm studies.8,9 A coupled microfluidic-imaging mass spectrometry approach would provide the chemical molecular spatial mapping needed to better address the scientific challenge of biofilms.Recently, we developed a portable microfluidic reactor, System for Analysis at the Liquid Vacuum Interface (SALVI),10,11 which overcame the grand challenge of studying liquids with high volatility and liquid interfaces using surface sensitive vacuum instruments. SALVI enables direct imaging of liquid surfaces using electron or ion/molecular based vacuum techniques. Our microfluidic approach used a polydimethylsiloxane (PDMS) microchannel fully enclosed with a thin silicon nitride (SiN) membrane (100 nm thick). For visualization, 2 μm diameter holes were opened in the SiN membrane in vacuo. These detection windows were dynamically drilled using the time-of-flight secondary ion mass spectrometry (ToF-SIMS) primary ion beam (e.g., Bi+).12Unlike liquid sample holders for transmission electron microscopy and scanning transmission electron microscopy, SALVI is self-contained and portable.13 As a result, it can potentially be used in many finely focused analytical tool with minimal adaptation.10 The analytical performance of SALVI has been demonstrated with a variety of analytes ranging from biology to material sciences.14,15 Unlike most microfluidic applications that are only suitable under ambient conditions (e.g., separations, cell and small amount sample manipulation, and thermal flow-sensors),16–18 SALVI is compatible with both in situ ambient and in vacuo spectroscopy analysis and imaging.19 Biofilms have been successfully cultivated inside the microfluidic channel and imaged using correlative confocal laser scanning microscopy (CLSM) and ToF-SIMS.20Our approach opens a new avenue to study biological sample in their natural state. Although ToF-SIMS has been widely used for providing molecular signatures of organic and biological molecules in complex biological systems21,22 or lipid spatial mapping,23 the vacuum-based ToF-SIMS generally requires solid (either dried24 or cryo treated25) samples. Here, we report ToF-SIMS two dimensional (2D) and three dimensional (3D) chemical images of hydrated biofilms. In situ time and space-resolved identifications of fatty acid (FA) fragments characteristic of Shewanella are illustrated by 3D images reconstructed from the ToF-SIMS depth profile time series. Principal component analysis (PCA) further elucidates biofilm chemical and spatial heterogeneity and shows the key chemical component at different depth and location of the biofilm including the biofilm-surface attachment interface.For all growth experiments, two samples were cultured simultaneously. At days 5 and 6, one sample was harvested for immediate analysis, respectively, using a ToF-SIMS V spectrometer (IONTOF GmbH, Münster, Germany). Similar results were obtained from both samples, because the biofilm-attachment surface was probed. For consistency, only day 6 data are shown here, while additional data are provided in the supplementary material.28 2D and 3D image visualizations were obtained using the IONTOF instrument software. PCA was performed using MATLAB R2012a (MathWorks, Inc., Natick, MA, USA). 2D images of .bif format were converted and integrated into a matrix. Data were pretreated by normalization to total ions, square root transformation, and then mean centering.26 For m/z spectra PCA, unit mass peaks from m/z 199 to m/z 255 were used (see Figure S-228). Unit mass peaks from m/z 1–300 were also used and results are comparable (see Figure S-328). Five characteristic FA peaks (m/z 199, 213, 227, 241, and 255, corresponding to C12, C13, C14, C15, and C16 FAs) were used in image PCA.27 Images representing each PC were reconstructed from the score matrix using the red, green, and blue (RGB) color scale.Using depth profiling, we drilled through the SiN membrane and collected depth-resolved images of the live biofilm (Figure 1(a)). Our analysis of the negative ToF-SIMS spectra after SiN punch-through showed Shewanella FA fragments in the m/z 195–255 range.20 From the depth profile time series, we selected five regions (highlighted as I, II, III IV, and V) within the FA m/z range to visualize 2D spatially resolved images collected for 46 s (1000 scans) before (I), during (II), or after (III, IV, V) SiN membrane punch-through.20 When false color 2D images of FA fragments characteristic of Shewanella biofilms were selected from the dynamic depth profiling data, differences were observed (Figure 1(b)) among the five regions. Furthermore, the biofilm images after SiN membrane punch-through (III, IV, V) displayed variations across the 2 μm diameter surfaces, with C12 (m/z 199) being distributed across regions III, IV, and V and C15 (m/z 241) FAs mostly in region V (see Figure S-4 for additional FA images28). This suggested that depth-resolved chemical heterogeneities were present in the biofilm. To illustrate, we reconstructed the 2D images from depth profiling data within the biofilm region (from the beginning of III through the end of V) and show spatially resolved 3D chemical images within the entire sample (Figure 1(c) and movies S1-S328). The reconstructed 3D images revealed the heterogeneous spatial distribution overlay for C12 (red) and C15 (green) FAs during 302 s biofilm depth profiling from day 5 (Figure S-528) and day 6 (Figure 1(c)).Open in a separate windowFIG. 1.(a) ToF-SIMS depth profiling of the day 6 biofilm attached to the SiN membrane in the microfluidic channel. Five regions representing sample before SiN punch-through (I) during punch-through (II) or within the biofilm region (III, IV, and V) are illustrated. (b) 2D false color images of day 6 biofilm FAs at the five time regions highlighted in (a). (c) Reconstructed 3D day 6 biofilm images showing FA fragment distributions within the entire biofilm region (III–V, 302 s). The time axis represents depth profiling from near the SiN surface into the biofilm. (d) Spectra PCA score plot of day 6 biofilm showing the differences and similarities among selected five regions (m/z 199–255). A 95% confidence limit for each region was defined by an ellipse with the same color to the corresponding region clusters. (e) Loadings of PC1 and PC2 corresponding to (d) and the plot of PC variance contributions.Spectral PCA was used to analyze the m/z spectra. The deepest region (V) into the biofilm was the most different from the other two biofilm regions (III and IV), further confirming the heterogeneities observed in the 2D images (e.g., C12 and C15 FA fragments) contributing most to this spatial difference. In addition, C12 FA fragments played a key role in the biofilms imaged near the SiN membrane attachment surface (III and IV). When inspected individually, C12 FAs were observed throughout the entire biofilm region, suggesting that C12 FA fragments may play a role in biofilm attachment to a surface and they may be main components of EPS throughout the biofilm. In contrast, C15 FAs were more abundant deeper within the biofilm, indicating that they may be more relevant to bacteria cells themselves.Uniform sputtering rate was assumed during depth profiling. To better determine the depth and shape of the SIMS ionization crater, AFM measurements were collected using an agarose sample in the SALVI reactor as a proxy for the biofilms (Figure S-628). The AFM results showed that the 100 nm SiN was drilled through and confirmed that the biofilm interface was probed by ToF-SIMS. Ideally, real-time correlative AFM and ToF-SIMS measurements will be needed due to the self-healing property of biofilms. However, such capability is currently under development.To further analyze chemical differences within biofilms, we performed ToF-SIMS depth profiling at three locations along the microchannel; namely, the inlet, center, and outlet as illustrated in Figure S-1(b).28 At each location, we defined the five regions described in Figure 1(a), and 2D image PCA analysis was conducted on the biofilm region (from the beginning of III through the end of V) to visualize the chemical distributions on day 6. Figure 2(a) shows the loading plots for the m/z peaks that contribute to each PC image (Figure 2(b)). The first three PCs explained 93.79% of the variance within the data. For PC1, the strongest positive loading fragments were C12 and C15 FAs, which are the bright red areas in three PC1 images. The C12 FAs were the main contributor to the green regions in the PC2 image. The strongest loading for PC3 in blue was C14 FAs. Compared to PC1 and PC2, PC3 played a limited contribution to the overall spatial distribution discrimination. The merged images give a demonstration of chemical spatial distribution of key components of biofilms in the liquid microenvironment.Open in a separate windowFIG. 2.(a) Image PCA loading plots illustrating the contribution of each FA peak in the day 6 biofilm at three locations within the microfluidic channel. The variance contributions of each PC are shown at the bottom. (b) Reconstructed false-color 2D PCA images in RGB corresponding to each PC scores at these locations along the microfluidic channel. The RGB composite images of the three key PCs are depicted in the bottom. Only data within the 2 μm diameter circle were considered in analysis.Our results show that SALVI and liquid ToF-SIMS studies of live biofilms offer dynamic, depth-resolved chemical mapping and produce 2D and 3D visualizations of spatial heterogeneity within a biofilm. Chemical imaging of biofilms near the attachment interface can enhance our understanding of biofilm formation in environmental, medical, and industrial settings. Our approach provides a universal portable platform and enables in situ probing of complex living biological systems potentially across multiple time and space scales. Because of the portability and vacuum compatibility, SALVI offers a valuable linkage with proteomic mass spectrometry via microfluidics and a nondestructive package for integrative in situ analysis of live biological systems in system biology. 相似文献
39.
Maintenance of cellular homeostasis and genome integrity is a critical responsibility of DNA double-strand break(DSB)signaling.P53-binding protein 1(53BP1)plays a critical role in coordinating the DSB repair pathway choice and promotes the non-homologous end-joining(NHEJ)-mediated DSB repair pathway that rejoins DSB ends.New insights have been gained into a basic molecular mechanism that is involved in 53BP1 recruitment to the DNA lesion and how 53BP1 then recruits the DNA break-responsive effectors that promote NHEJ-mediated DSB repair while inhibiting homologous recombination(HR)signaling.This review focuses on the up-and downstream pathways of 53BP1 and how 53BP1 promotes NHEJ-mediated DSB repair,which in turn promotes the sensitivity of poly(ADP-ribose)polymerase inhibitor(PARPi)in BRCA1-deficient cancers and consequently provides an avenue for improving cancer therapy strategies. 相似文献
40.
论体育科技写作的类别、特点与主要作用 总被引：2，自引：2，他引：0
体育科技写作有别于一般的中文写作,它是一门文理渗透的交叉学科,不仅涉及体育科学的专业知识,还涉及写作学、逻辑学、情报学、心理学、方法论等知识。着重探讨了体育科技写作的基本特点与主要作用 相似文献