SPOC论坛交互行为模式挖掘与学习成效分析

论坛是正式学习的辅助工具之一,可用来促进各成员之间的学习交流,学习者在论坛中表现与其学习成效强相关,然而在具体教学实践中存在交互缺失、交互参与度不高等现象。以“教育技术学研究方法”混合课堂中的SPOC论坛数据为研究对象,对其交互行为模式进行挖掘,并通过量化研究探究其对学习成效的影响。首先,采用文献分析法对国内外研究现状进行分析与总结。其次,采用社会网络分析法对SPOC论坛中参与交互的学习者进行特征刻画,并结合机器学习方法对学习者的交互模式进行聚类分析,将学习者分为活跃者、追随者和沉默者,并将该三类学习者在论坛中的交互特征与其学习成绩进行量化建模分析。最后,采用语义分析法对学习者的情感进行建模,并将不同类型学习者的情感与其学习成绩进行相关性分析。研究表明,在混合课堂中,不同类型学习者的交互频次与其学习成效间无相关性影响,而SPOC论坛中情绪词语出现的频次与其课程成绩间存在显著相关性,进而提出三条针对性的学习策略,旨在为提升混合式课堂学习质量提供借鉴。

城乡融合发展:实现共同富裕的实践路径和制度框架

城乡二元体制的刚性和系统性,是我国在创造史无前例经济奇迹的同时,产生的中等收入群体增长相对较缓、贫富差距相对较大的重大结构性问题,在某种程度上也是推进共同富裕必须突破的中心所在。在今天和未来构建以国内大循环为主体、国内国际双循环相互促进的新发展格局中,实现农民真正市民化和自主选择、城乡基本公共服务均等化、城市偏好政策的全面取消等,缩小城乡差距乃至使其消失,是深入推进城乡融合发展的必然要求,也是实现全体人民共同富裕的前提。本文围绕深化城乡融合发展、促进共同富裕这一中心命题,尝试从制度创新、农村农业产业升级、基本民生保障、社会公共需求、农业财政制度和城乡治理体制六个方面提出一套实践路径和制度框架。

Single‐atomic Co‐B_(2)N_(2)sites anchored on carbon nanotube arrays promote lithium polysulfide conversion in lithium-sulfur batteries

Due to low cost,high capacity,and high energy density,lithium–sulfur(Li–S)batteries have attracted much attention;however,their cycling performance was largely limited by the poor redox kinetics and low sulfur utilization.Herein,predicted by density functional theory calculations,single‐atomic Co‐B2N2 site‐imbedded boron and nitrogen co‐doped carbon nanotubes(SA‐Co/BNC)were designed to accomplish high sulfur loading,fast kinetic,and long service period Li–S batteries.Experiments proved that Co‐B2N2 atomic sites can effectively catalyze lithium polysulfide conversion.Therefore,the electrodes delivered a specific capacity of 1106 mAh g−1 at 0.2 C after 100 cycles and exhibited an outstanding cycle performance over 1000 cycles at 1 C with a decay rate of 0.032%per cycle.Our study offers a new strategy to couple the combined effect of nanocarriers and single‐atomic catalysts in novel coordination environments for high‐performance Li–S batteries.

细胞自噬调控在肿瘤中作用的研究进展

自噬是溶酶体介导的细胞自行消化,其构成了一个被损坏的细胞器和长寿命蛋白质的循环动态途径,在机体内环境稳态和肿瘤发生机制中发挥着重大作用,以保证细胞在营养不足、肿瘤微环境等应激条件下可获得持续利用的能量,并以此来维持体内平衡及生存能力。自噬不仅依赖于肿瘤中的环境、细胞种类和阶段,而且还受肿瘤细胞与微环境之间相互串扰的调节。自噬在肿瘤的早期阶段能抑制肿瘤发生,然而肿瘤晚期阶段自噬促进肿瘤发生,并增加肿瘤细胞生长和转移。本文将就自噬机制及其在肿瘤细胞增殖发展中的作用进行综述,深入研究自噬在癌症生物学中作用,有助于针对自噬相关靶点抗肿瘤的新药设计和临床转化研究。

Analysis of Strategy for Extending Patent Protection of Rucaparib

As a knowledge-intensive and promising strategic emerging industry, the biomedical industry has high entry thresholds, large R&D investment, long cycle, high risk and high return. In all technical fields, the biomedical industry has the highest dependence on intellectual property rights, and the protection of pharmaceutical intellectual property rights by domestic and foreign biomedical enterprises also runs through the whole process of drug research and development. Extending the patent protection period of drugs as well as forming and strengthening patent fortresses requires a patent network that surrounds drugs to maximize the value of intellectual property protection, which is also the focus of every pharmaceutical company with patent rights. By analyzing the patent portfolio of Clovis Oncology Company in the United States on Rucaparib and the patent portfolio of other companies or applicants on Rucaparib, we can have a clearer understanding of the strategy of extending the patent protection period of a new drug product.

Research on Dispersion Compensation of 40 GB/s Optical Duo-Binary Coded Transmission System

A 40 Gb/s high speed optical transmission system is designed, and the different dispersion compensation schemes are adopted to realize the transmission of the optical duo-binary (ODB) signals over 120 km optical fiber. Optical duo-binary signals are generated by using a precoder, two low- pass filters (LPF) and one mach-zehnder modulator (MZM). Through combination of dispersion compensation fiber (DCF) and single mode fiber (SMF) in the transmission link, four different dispersion compensation schemes (pre-compensation, post-compensation and hybrid compensation (pre+ post) and hybrid compensation (post+ pre)) were compared. Analyzing Q factor, BER, eye diagrams and receiver sensitivity in several dispersion compensation schemes, the simulation results are: the cut-off frequency of LPF affects the transmission performance, and the hybrid compensation (post+ pre) scheme is the optimal dispersion compensation method.

PAPR Influence Analysis in 8QAM-OFDM Optical Access Systems

In this article, the peak to average power ratio (PAPR) performance of 8 quadrature amplitude modulation-orthogonal frequency division multiplexing (8QAM-OFDM) optical signals has been researched in broadband optical access system. The complementary cumulative distribution functions (CCDFs) are analyzed of two different 8QAM-OFDMsignals with 16, 32, 64, 128, 256, 512 sub- carriers by simulation. The simulation results show that, with the increase of the number of subcarrier, the PAPR value becomes higher. When the numbers of subcarrier are16 and 512, the PAPR of 8QAM-OFDM optical signals are smaller than 5.2 dB and 5.3 dB respectively. Hence, the number of sub-carriers should be chosen according to practical application.

A 16PSK-OFDM-FSO Communication System under Complex Weather Conditions

Free Space Optical (FSO) communication is one of the most promising access methods. But, the different weather conditions will affect the transceiver performance. In this paper, we build a FSO communication system with 16-ary phase shift key-orthogonal frequency division multiplexing (16PSK-OFDM) downstream signals. We analyze the transmission performance of 16PSK-OFDM optical signals under five different weather conditions (sunny, light rain, moderate rain, snow, and fog). The optical spectral diagrams, constellation diagrams, and bit error rate (BER) of the received signals are simulation measured and analyzed. The results show that the constellation diagram under sunny condition is clear, and the value of BER is about 10?4.2 after 16PSK-OFDM optical signals pass through 500 m FSO link. Note that, the constellation points are dispersed under the other weather conditions.

Application Research on Two Types of 8QAM-OFDM Optical Access Signals

In this paper, the downstream transmission performance of two types of 8QAM-OFDM optical signals in broadband optical access system has been analyzed. After modulation and coding, two types of 10 Gbit/s 8QAM-OFDM optical access signals are downstream transmitted over 1 km, 10 km, 20 km and 40 km single mode fibers (SMFs) and received successfully. Different transmission distances impact on the bit error rate (BER) of the received signal is analyzed by simulation, while the signal to noise ratio (SNR) is 20 dB. The results show that, while the transmission distance is shorter than 10 km, the BER values of two types of 8QAM-OFDM optical signals are smaller than 10?10. As the above optical access signals are transmitted over 40 km SMF, the BER value of the first type of 8QAM-OFDM signals is bigger than 10?6, and the BER of the other type of 8QAM-OFDM signals is smaller than 10?6.

Optical 64QAM-OFDM Transmission Systems with Different Sub-Carriers

In this paper, the transceiver performance of optical 64QAM-OFDM signals with different sub-car- riers is studied. Firstly, we build a 40Gbit/s optical coherent 64QAM-OFDM transmission system. 64QAM-OFDM optical signals with 16, 32, 64, 64, 128, 256 and 512 sub-carriers are transmitted over 100 km single mode fiber (SMF). Then, the optical spectrum diagrams before and after transmission, the bit error rate (BER) and constellation diagrams of received signals were compared. The simulation results show that, with the number of sub-carriers increasing, the value of PAPR will gradually increase and the quality of the received optical signals will deteriorate. Moreover, with the number of sub-carriers increasing, the computational complexity will increase when digital signal processing (DSP) is used. Therefore, we should choose the optimal number of sub-carriers, and the PAPR influence and BER are also considered for achieving effective transmission.

微小RNA-29a-3p调节卷曲蛋白4表达影响高脂血症大鼠种植体骨整合的实验研究

目的研究microRNA-29a-3p(miR-29a-3p)对高脂环境下大鼠骨髓间充质干细胞(BMSCs)成骨分化和高脂血症大鼠种植体骨整合的影响及其作用位点。方法 1)体外实验:对BMSCs分别进行普通和高脂成骨诱导,通过逆转录实时定量聚合酶链反应和Western blot检测miR-29a-3p及成骨相关因子碱性磷酸酶(ALP)、Runt相关基因2(Runx2)的基因和蛋白质表达;高脂培养的BMSCs分别转染miR-29a-3p模拟物、抑制物及阴性对照(NC)质粒,RT-qPCR检测miR-29a-3p、ALP及Runx2基因表达情况,Western blot检测ALP、Runx2蛋白表达情况。通过靶基因预测软件(Target Scan、MiRNA.org等)预测miR-29a-3p与成骨相关的靶基因为卷曲蛋白4(Fzd4),双荧光素酶报告检测miR-29a-3p与Fzd4的相互作用关系。2)体内实验:高脂血症大鼠为实验组,普通大鼠为对照组,两组分别植入种植体,检测种植体周围骨组织中miR-29a-3p、ALP、Runx2的表达差异;行种植体-骨组织的硬组织切片,亚甲基蓝-酸性品红染色,进行组织学观察。分别将miR-29a-3p过表达慢病毒载体及空白对照慢病毒载体注射入高脂血症大鼠,种植体植入后3、10 d检测种植体周围骨组织中ALP、Runx2的表达变化以研究miR-29a-3p对高脂血症大鼠成骨的作用。结果高脂组与普通组相比,ALP、Runx2和miR-29a-3p表达下调,BMSCs成骨分化能力下降。miR-29a-3p模拟物组与抑制物组相比,ALP、Runx2表达升高,BMSCs成骨分化能力增强。体内实验也得到了相似结果。双荧光素酶报告基因分析证实miR29a-3p通过直接结合3’-UTR抑制Fzd4表达。结论miR-29a-3p对高脂环境下大鼠BMSCs成骨分化起正向调节作用,可直接与Fzd4结合调节成骨分化;mi R-29a-3p能够促进高脂血症大鼠种植体周围成骨标志基因的表达,有利于骨整合。

Joint Design of Coalition Formation and Semi-Blind Channel Estimation in Fog Radio Access Networks

Coordinated signal processing can obtain a huge transmission gain for Fog Radio Access Networks(F-RANs).However,integrating into large scale,it will lead to high computation complexity in channel estimation and spectral efficiency loss in transmission performance.Thus,a joint cluster formation and channel estimation scheme is proposed in this paper.Considering research remote radio heads(RRHs)centred serving scheme,a coalition game is formulated in order to maximize the spectral efficiency of cooperative RRHs under the conditions of balancing the data rate and the cost of channel estimation.As the cost influences to the necessary consumption of training length and estimation error.Particularly,an iterative semi-blind channel estimation and symbol detection approach is designed by expectation maximization algorithm,where the channel estimation process is initialized by subspace method with lower pilot length.Finally,the simulation results show that a stable cluster formation is established by our proposed coalition game method and it outperforms compared with full coordinated schemes.

Measurement of the remnant magnetic-field in Lorentz mode using permalloy

A novel method was reported to measure the remnant magnetic field in Lorentz mode in a FEI Tecnai F20 transmission electron microscope equipped with a Lorentz lens. The movement of the circle Bloch line of the cross-tie wall in Permalloy is used to measure the remnant magnetic field by tilting the specimen and adjusting the objective lens current. The remnant magnetic field is estimated to be about 17 Oe, in a direction opposite to that of the objective lens magnetic field. The remnant magnetic field can be compensated by adjusting the value of the objective lens current.

Speech Resampling Detection Based on Inconsistency of Band Energy

Speech resampling is a typical tempering behavior,which is often integrated into various speech forgeries,such as splicing,electronic disguising,quality faking and so on.By analyzing the principle of resampling,we found that,compared with natural speech,the inconsistency between the bandwidth of the resampled speech and its sampling ratio will be caused because the interpolation process in resampling is imperfect.Based on our observation,a new resampling detection algorithm based on the inconsistency of band energy is proposed.First,according to the sampling ratio of the suspected speech,a band-pass Butterworth filter is designed to filter out the residual signal.Then,the logarithmic ratio of band energy is calculated by the suspected speech and the filtered speech.Finally,with the logarithmic ratio,the resampled and original speech can be discriminated.The experimental results show that the proposed algorithm can effectively detect the resampling behavior under various conditions and is robust to MP3 compression.

Combining single-cell RNA sequencing with spatial transcriptome analysis reveals dynamic molecular maps of cambium differentiation in the primary and secondary growth of trees

Primary and secondary growth of the tree stem are responsible for corresponding increases in trunk height and diameter.However,our molecular understanding of the biological processes that underlie these two types of growth is incomplete.In this study,we used single-cell RNA sequencing and spatial transcriptome sequencing to reveal the transcriptional landscapes of primary and secondary growth tissues in the Populus stem.Comparison between the cell atlas and differentiation trajectory of primary and secondary growth revealed different regulatory networks involved in cell differentiation from cambium to xylem precursors and phloem precursors.These regulatory networks may be controlled by auxin accumulation and distribution.Analysis of cell differentiation trajectories suggested that vessel and fiber development followed a sequential pattern of progressive transcriptional regulation.This research provides new insights into the processes of cell identity and differentiation that occur throughout primary and secondary growth of tree stems,increasing our understanding of the cellular differentiation dynamics that occur during stemgrowth in trees.

高压氧联合纳美芬对弥漫性轴索损伤的临床应用效果

目的探讨高压氧(HBO)联合纳美芬对弥漫性轴索损伤(DAI)患者促醒治疗的临床效果。方法选取南通大学第二附属医院神经外科和急诊科自2012年8月至2019年8月收治的160例DAI患者,按照随机数字表法将患者分为常规治疗组、HBO治疗组、纳美芬治疗组和HBO联合纳美芬治疗组,各40例。随访3个月,采用GOS评分评定治疗效果,比较4组患者的预后良好率。结果HBO联合纳美芬治疗组的预后良好率较常规治疗组有所提高,差异有统计学意义(P<0.05)。结论HBO联合纳美芬对DAI昏迷患者能促进意识恢复,加速苏醒,改善生活状态。

A review of concentrated photovoltaic-thermal(CPVT) hybrid solar systems with waste heat recovery(WHR)

In conventional photovoltaic(PV) systems, a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%. As the dissipated heat can be recovered for various applications, the wasted heat recovery concentrator PV/thermal(WHR CPVT) hybrid systems have been developed. They can provide both electricity and usable heat by combining thermal systems with concentrator PV(CPV) module, which dramatically improves the overall conversion efficiency of solar energy.This paper systematically and comprehensively reviews the research and development of WHR CPVT systems. WHR CPVT systems with innovative design configurations, different theoretical evaluation models and experimental test processes for several implementations are presented in an integrated manner. We aim to provide a global point of view on the research trends, market potential, technical obstacles, and the future work which is required in the development of WHR CPVT technology. Possibly, it will offer a generic guide to the investigators who are interested in the study of WHR CPVT systems.

Experiment study of a quartz tube falling particle receiver

This paper presents an experimental evaluation of a specially designed falling particle receiver. A quartz tube was used in the design, with which the particles would not be blown away by wind. Concentrated solar radiation was absorbed and converted into thermal energy by the solid particles flowed inside the quartz tube. Several experiments were conducted to test the dynamic thermal performance of the receiver on solar furnace system. During the experiments, the maximum particle temperature rise is 212~C, with an efficiency of 61.2%, which shows a good thermal performance with a falling distance of 0.2 m in a small scale particle receiver. The average outlet particle temperature is affected by direct normal irradiance （DNI） and other factors such as wind speed. The solid particles obtain a larger viscosity with a higher temperature while smaller solid particles are easier to get stuck in the helix quartz tube. The heat capacity of the silicon carbide gets larger with the rise of particle temperature, because as the temperature of solid particles increases, the temperature rise of the silicon carbide decreases.

Fighting Against COVID-19 at the Community Level—Wuhan City,Hubei Province,China,2020

Since December 2019,an increasing number of cases of pneumonia with unknown etiology(PUE)—later named as coronavirus disease 2019(COVID-19)by the World Health Organization(WHO)—was identified in Wuhan(1–3),a large city of 11 million people in central China,and the basic reproductive number(R0)was estimated to be 2.2(95%CI:1.4 to 3.9)(4).On March 11,2020,the WHO formally announced COVID-19 a worldwide pandemic based on the alarming levels of spread and severity and by the alarming levels of inaction(5).Although there is neither a vaccine nor specific medication available,the pandemic was well contained in China by the strict introduction of nonpharmacological interventions(NPIs)(6).

The von Kries chromatic adaptation transform and its generalization

Most viable modern chromatic adaptation transforms(CATs),such as CAT16 and CAT02,can trace their roots both conceptually and mathematically to a simple model formulated from the hypotheses of Johannes von Kries in 1902,known as the von Kries transform/model.However,while the von Kries transform satisfies the properties of symmetry and transitivity,most modern CATs do not satisfy these two important properties.In this Letter,we propose a generalized von Kries transform,which satisfies the symmetry and transitivity properties in addition to improving the fit to most available experimental visual datasets on corresponding colors.