教育元宇宙支持下的深度学习路径研究

现阶段,深度学习存在情境相对孤立和简化、学习者间缺乏交流沟通、学习资源片面化、学习方式固定化、评价机制不完善等问题。教育元宇宙具有的多元融合技术、独有特征,可以为改变深度学习现状提供更多的可能性,并为深度学习开辟新兴发展道路。教育元宇宙支持下的深度学习聚焦新时代教育理念、强化教育政策变革、推动信息科技与教育教学深度融合。鉴于此,依托多重底层技术建构由境脉系统与资源系统组成,具有沉浸式、全方位、多元化、开放性、创造性、探究性的深度学习场域。在此基础上,秉承“以学习者为中心”理念,在教师的指导下和多元智能化评价反馈系统支持下,为实现学习者的自我反思与创新,构建包含体验、发现问题(任务)、分析对话、实践(验证)、迁移五种类型的多模态个性化学习方式。学习者在此过程中掌握学科专业知识、提高解决问题能力、把握高阶思维、形成正确的价值观与核心素养、主动进行自我反思,最终成为推动新时代社会历史发展的人才。

Triangulation of red sprites observed above a mesoscale convective system in North China

The triangulation of red sprites was obtained, based on concurrent observations over a mesoscale convective system(MCS) in North China from two stations separated by about 450 km. In addition, broadband sferics from the sprite-producing lightning were measured at five ground stations, making it possible to locate and identify the individual causative lightning discharges for different elements in this dancing sprite event. The results of our analyses indicate that the sprites were produced above the trailing stratiform region of the MCS, and their parent strokes were located mainly in the peripheral area of the stratiform. The lateral offset between sprites and causative strokes ranges from a few km to more than 50 km. In a particularly bright sprite, with a distinct halo feature and streamers descending down to an altitude of approximately 48 km, the sprite current signal identified in the electric sferic, measured at a range of about 1,110 km, peaked at approximately 1 ms after the return stroke.

Freeze-thaw processes of active-layer soils in the Nanweng'he River National Natural Reserve in the Da Xing'anling Mountains,northern Northeast China

The active-layer soils overlying the permafrost are the most thermodynamically active zone of rock or soil and play important roles in the earth-atmosphere energy system. The processes of thawing and freezing and their associated complex hydrothermal coupling can significantly affect variation in mean annual temperatures and the formation of ground ice in permafrost regions. Using soil-temperature and-moisture data obtained from the active layer between September 2011 and October 2014 in the permafrost region of the Nanweng'he River in the Da Xing'anling Mountains, the freeze-thaw characteristics of the permafrost were studied. Based on analysis of ground-temperature variation and hydrothermal transport characteristics, the thawing and freezing processes of the active layer were divided into three stages:(1) autumn-winter freezing,(2) winter freeze-up, and(3) spring-summer thawing. Variations in the soil temperature and moisture were analyzed during each stage of the freeze-thaw process, and the effects of the soil moisture and ground vegetation on the freeze-thaw are discussed in this paper. The study's results show that thawing in the active layer was unidirectional, while the ground freezing was bidirectional(upward from the bottom of the active layer and downward from the ground surface).During the annual freeze-thaw cycle, the migration of soil moisture had different characteristics at different stages. In general, during a freezing-thawing cycle, the soil-water molecules migrate downward, i.e., soil moisture transports from the entire active layer to the upper limit of the permafrost. In the meantime, freeze-thaw in the active layer can be significantly affected by the soil-moisture content and vegetation.

Selective Adsorption of Ag(I) from Electronic Waste Leachate Using Modified Silk Sericin

A novel biosorbent was synthesized by grafting bisthiourea(BTU)on a silk sericin(SS)matrix.This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy(FTIR),zeta potential measurements,elemental analysis,and X-ray photoelectron spectroscopy(XPS).As revealed by the adsorption experiments,both BTU-SS and SS showed low affinity towards coexisting base metallic ions in Ag(I)-Cu(II)-Zn(II)-Ni(II)-Pb(II)electronic waste leachate mixtures,while their adsorption capacities towards Ag(I)reached 30.5 and 10.4 mg∙g-1 at a pH of 5.0,respectively.BTU-SS showed higher selectivity towards Ag(I)than SS,as revealed by the Ag(I)partition coefficients between the biosorbents and the leachate(16634.6 and 403.3,respectively).As further demonstrated by column experiments,BTU-SS allowed the separation of Ag(I)from an electronic waste leachate.Thermodynamic studies showed that the adsorption of Ag(I)was exothermic and spontaneous,while adsorption kinetic experiments revealed that chemisorption dominated the adsorption process with activation energies of 47.67 and 53.27 kJ∙mol-1 for BTU-SS and SS,respectively.FTIR and XPS analyses of fresh and Ag(I)-loaded BTU-SS further revealed an adsorption mechanism mainly involving electrostatic and coordination interactions.

Study on Efficient Multiplication of Blueberry(Vaccinium corymbosum)Plantlets in Swinging type Temporary Immersion Bioreactors System(S-TIBs)

The swinging type temporary immersion bioreactors system （S-TTBs） is a kind of new and advanced method of tissue culture. The efficient multiplica- tion technology of blueberry （ Vaccinium corymbosum） plantlets in S-TTBs was systematically studied through L9 （3^4） orthogonal experiment with three factors （culture medimn volmne, swing angle, and inoculation density） and completely randomized experiment with two factors （swing frequency and immersion time）. The results showed that the optimal culture parameters were set as follows： the culture medium volume of 250 nil/bottle, the swing angle at 45 ° , and the inoculation density of 60 plantlets/bottle. The optimal swing frequency was 1 time/6 h, and the immersion time was set as 60 s.

819份不同痰标本来源分枝杆菌培养结果分析

目的分析涂阳培阴及涂阳培养污染的原因分析,为了解决降低涂阳培阴率及涂阳培养污染率提出更合理的操作流程。方法 2013年8月-2014年12月实验室共接收各区实验室耐多药可疑患肺结核涂阳的痰标本和本单位的门诊及住院确诊肺结核病人涂阳的痰标本共819份,进行分离培养。对分离培养阴性及污染结果进行分析。结果 819份痰涂片阳性标本分离培养结果:分离培养阳性709份,占86.57%(709/819);培养阴性77份,占9.47%(77/819);培养污染33份,占4.03%(33/819);总涂阳培阴77份痰标本中:1条-8条23份占29.87%(23/77);1+42份占54.54%(42/77);2+10份占12.98%(10/77);3+1份占1.29%(1/77);4+1份占1.29%(1/77)。结论涂阳培阴标本涂片痰菌量分布在1+>8和条>2+之间,B组比A组患者痰标本出现涂阳培阴率和污染率高,应注意各个步骤操作流程细节。

On the upper bounds of (1,0)-super solutions for the regular balanced random (k,2s)-SAT problem

This paper explores the conditions which make a regular balancedrandom(k,2s)-CNFformula(1,O)-unsatisfiable with high probability.The conditions also make a random instance of the regular balanced(k-1,2(k-1)s)-SAT problem unsatisfiable with high probability,where the instance obeys a distribution which differs from the distribution obeyed by a regular balanced random(k-1,2(k-1)s)-CNF formula.Let F be a regular balanced random(k,2s)-CNF formula where k≥3,then there exists a number so such that F is(1,O)-unsatisfiable with high probability if s>so.A numerical solution of the number so when k e(5,6,...,14)is given to conduct simulated experiments.The simulated experiments verify the theoretical result.Besides,the experiments also suggest that F is(1,O)-satisfiable with high probability if s is less than a certain value.

铂–镍双原子分散在具有新型(NiPt)-N_(4)C_(2)构型的氮掺杂碳纳米结构上用于协同电催化析氢反应

单原子催化剂具有原子利用率高、活性中心明确、催化中心原子配位数低等优点,有望提高电催化性能.具有相邻杂原子的双原子催化剂(DAC)有望发挥两个原子的协同作用,从而进一步提高活性.在本文中,我们报道了一种PtNi-NC催化剂,该催化剂由固定在氮掺杂碳基底上的PtNi双原子构成,该基底采用原子层沉积技术合成.X射线吸收光谱证实了Pt–Ni双原子的存在.所制备的PtNi-NC催化剂具有优异的催化活性,在10 m A cm^(-2)的电流密度下,酸性介质中析氢反应(HER)的过电位为30 m V,与市售20 wt%Pt/C相当.特别值得注意的是,PtNi-NC具有比20 wt%Pt/C更高的质量活性,约为其21倍.密度泛函理论计算表明,Pt–Ni双原子通过调节局部电子结构和优化电荷分布产生协同效应,有助于优化吸附性能和增强电催化性能.这项工作为DAC的制备提供了新途径,揭示了它们在电催化HER等领域的应用潜力.

Clinical characteristics of radiation-induced optic neuropathy:A single-center retrospective study

Purpose:To observe the clinical and imaging characteristics of radiation-induced optic neuropathy(RION).Methods:We retrospectively reviewed the clinical data of 43 patients(69 eyes)who were diagnosed with RION at the Chinese PLA General Hospital from 2010 to 2021.Results:The latency from radiotherapy to onset of visual loss ranged from 1 to 132(36.33±30.48)months.Optic disc pallor and optic disc edema were found in 27.0%(10/37)and 8.1%(3/37)of the eyes,respectively,within 2 months.After treatment,the best corrected visual acuity(BCVA)was restored in 24.6%(17/69)of the eyes and the final BCVA improved in 13.0%(9/69)of the eyes.An 82.5%(33/40)of the eyes with magnetic resonance imaging(MRI)showed enhancement of the affected optic nerve,mostly(69.7%)in the intracranial segment,and 36.4%(12/33)of the eyes with expansion and T2-high signals also showed enhancement of the affected optic nerve.The superior retinal nerve fiber layer(RNFL)and the outer circle superior quadrant(OS)of the inner limiting membrane to retinal pigment epithelium(ILM-RPE)layer thinned significantly during the first month.The center of the ILM-RPE layer thickened significantly during the first two months and the inner circle temporal quadrant(IT)of the ILM-RPE layer thickened significantly from the third to sixth month.The RNFL thinned significantly after 6 months except for the temporal quadrant,and the average inner circle superior quadrant(IS)and outer circle of the ILM-RPE layer thinned significantly after 6 months.There was no significant difference between hyperbaric oxygen therapy(HBOT)and high-dose intravenous methylprednisolone(IVMP)therapy in improving BCVA recovery or final BCVA(P>0.05).Conclusions:The structural damage of the RNFL and ILM-RPE layer occurred during the first month,the RNFL showed progressive thinning during the follow-up period,while the ILM-RPE layer showed thinning during the first month,thickening from the third to sixth month,and thinning after 6 months.There was a discrete region of enhancement of the optic nerve,often with expansion and high-T2 signals on MRI.HBOT and high-dose IVMP therapy were hardly effective for treating RION in the non-acute stage.

Vertical diversity of sediment bacterial communities in two different trophic states of the eutrophic Lake Taihu, China

Vertical diversity of sediment bacterial communities in 2 different trophic states （macrophyte-dominated and algae-dominated） of the large shallow eutrophic Lake Taihu, China, were investigated using denaturing gradient gel electropfioresis （DGGE） and 16S rRNA sequence analysis. Clustering analysis of DGGE profiles showed that different clusters were recognized in different depths of sediment cores in the 2 lake trophic states. Analyses of the bacterial diversity, as estimated by the Shannon index （H＇）, showed that different sediment layers of the macrophyte-dominated state had higher diversity than the algae-dominated state. In addition, bacterial diversity of the sediment in the macrophyte-dominated state changed abruptly throughout the layers, but bacterial diversity of the algae-dominated state decreased gradually with sediment depth. Phylogenetic analysis showed that Proteobacteria was the most abundant phylum in the middle sediment of the 2 lake trophic states. In the macrophyte-dominated state, clone sequences related to Betaproteobacteria （50.0%） were the most abundant, followed by Epsilonproteobacteria （21.1%）, Acidobacteria （7.9%）, Deltaproteobacteria （7.9%）, Chloroflexi （7.9%）, and Bacteroidetes （5.3%）; whereas in the algae-dominated state, sequences affiliated with Betaproteobacteria （84.4%） were predominant, followed by Deltaproteobacteria （12.5%） and Acidobacteria （3.1%）. Canonical correspondence analysis showed that organic matter and pH play key roles in driving the vertical changes of bacterial community composition.

Phytoplankton community from Lake Taihu,China,has dissimilar responses to inorganic and organic nutrients

To evaluate the response of phytoplankton from Lake Taihu to different types of nutrients, the phytoplankton responses were measured after adding inorganic nitrogen （N） and phosphorus （P） or decomposed algal scum （Microcystis spp.） into the lake water. Both types of nutrients promoted an increase in phytoplankton biomass as determined by chlorophyll a and algal wet weight. The addition of decomposed algal scum resulted in a significantly greater phytoplankton response than the addition of inorganic N and P alone. The dissolved inorganic N and P in the inorganic nutrient treatment were found not limit phytoplankton growth. The higher algal biomass obtained in the treatment with decomposed algal scum indicated the importance of other organic nutrients besides N and P such as trace elements, as well as the importance of the form of N since the levels of ammonia nitrogen （NH4^＋-N） from the decomposed algal treatment were actually higher than that of the inorganic N and P addition. Microcystis spp. （Cyanobacteria）, Scenedesmus spp. （Chlorophyta） and Synechocystis spp. （Cyanobacteria） were the dominant taxa in the control, inorganic N and P treatment, and the decomposed algal scum treatment, respectively. Microcystis never bloomed in response to both types of nutrient additions indicating that the bloom propagation is not solely related to nutrient additions, but may be related to the absence of selective grazing from zooplankton.

Properties of the satisfiability threshold of the strictly d-regular random(3,2s)-SAT problem

A k-CNF(conjunctive normal form)formula is a regular(k,s)-CNF one if every variable occurs s times in the formula,where k≥2 and s>0 are integers.Regular(3,s)-CNF formulas have some good structural properties,so carry-ing out a probability analysis of the structure for random formulas of this type is easier than conducting such an analysisfor random 3-CNF formulas.Some subclasses of the regular(3,s)-CNF formula have also characteristics of intractabilitythat differ from random 3-CNF formulas.For this purpose,we propose strictly d-regular(k,2s)-CNF formula,which is aregular(k,2s)-CNF formula for which d≥0 is an even num-ber and each literal occurs s-d/2 or s+d/2 times(the literals from a variable x are x and-x,where x is positive and-x isnegative).In this paper,we present a new model to generatestrictly d-regular random(k,2s)-CNF formulas,and focuson the strictly d-regular random(3,2s)-CNF formulas.Let F be a strictly d-regular random(3,2s)-CNF formula suchthat 2s>d.We show that there exists a real number so suchthat the formula F is unsatisfiable with high probability whens>so,and present a numerical solution for the real numberso.The result is supported by simulated experiments,and isconsistent with the existing conclusion for the case of d=0.Furthermore,we have a conjecture:for a given d,the strictlyd-regular random(3,2s)-SAT problem has an SAT-UNSAT(satisfiable-unsatisfiable)phase transition.Our experimentssupport this conjecture.Finally,our experiments also showthat the parameter d is correlated with the intractability of the 3-SAT problem.Therefore,our research maybe helpful for generating random hard instances of the 3-CNF formula.

PtHAK5, a candidate for mediating high-affinity K^+ uptake in the halophytic grass, Puccinellia tenuiflora

Puccinellia tenuiflora is a typical salt-excluding halophytic grass with strong salt-tolerance, which enhances tolerance by restricting Na^+influx as well as having a strong selectivity for K^+ over Na^+. The HAK5 K^+ transporters generally modulate effective K^+acquisition in plants, especially under low K^+ condition. In this study,Pt HAK5 from P. tenuiflora was isolated by RT-PCR and characterized using yeast complementation. The results showed Pt HAK5 consisted of 784 amino acids and shared over 80% homology with the identified high-affinity K^+ transporter HAK5 from other higher plants. The expression of PtHAK5 rescued the K^+ -uptake-defective phenotype of yeast strain CY162. In conclusion, PtHAK5 is a candidate for mediating high-affinity K^+ uptake under low K^+ conditions.

Differences in the involved sites among different types of demyelinating optic neuritis in traditional MRI examination:A systematic review and meta-analysis

Background:Magnetic resonance imaging(MRI)plays a significant role in assessing optic neuropathy and providing more detailed information about the lesion of the visual pathway to help differentiate optic neuritis from other visual disorders.This study aims to systematically review the literature and verify if there is a real difference in lesion location among different demyelinating optic neuritis(DON)subtypes.Methods:A systematic search was conducted including 8 electronic databases and related resources from the establishment of the database to August 25th,2020.We classified DON into 5 subtypes and divided the visual pathways into five segments mainly comparing the differences in the involved visual pathway sites of different subtypes.Results:Fifty-five studies were included in the analysis,and the abnormal rate was as high as 92%during the acute phase(within 4 weeks of symptom onset).With respect to lesion location,the orbital segment of the optic nerve was the most frequently involved(87%),whereas optic tract involvement was very rare.Involvement of the orbital segment was more common in myelin oligodendrocyte glycoprotein antibody-related optic neuritis(MOGON)(78%)and chronic relapsing inflammatory optic neuropathy(CRION)(81%),while the lesion was found to be located more posteriorly in neuromyelitis optica spectrum disorder-related optic neuritis(NMOSD-ON).With respect to lesion length,approximately 77%of MOG-ON patients had lesions involving more than half of the optic nerve length.Conclusions:MRI examination is recommended for DON patients in the acute phase.In MOG-ON,anterior involvement is more common and the involved length is mostly more than 1/2 of the optic nerve length,whereas posterior involvement,intracranial segment,optic chiasm,or optic tract,is more common in NMOSD-ON.

The clinical application of critical flicker fusion frequency in demyelinating optic neuritis

Purpose:To investigate the application of critical flicker fusion frequency(CFF)in demyelinating optic neuritis(DON).Methods:A cross-sectional study.A total of 127 eyes in 69 DON patients and 63 eyes in 33 healthy control(HC)groups were included between January 2021 to September 2021 from Department of Ophthalmology,PLA General Hospital.Patients underwent best-corrected visual acuity(BCVA),visual field,optical coherence tomography(OCT),flash visual evoked potential(F-VEP),and CFF examinations.The affected eyes were divided into aquaporins 4(AQP4-),myelin oligodendrocyte glycoprotein(MOG-),and double negative DON according to serum antibody;mild,moderate,severe degree visual impairment according to BCVA
0.5,0.1-0.5,<0.1;and 4 groups:<1,1~<3,3~<6 and>6 months according to time interval from onset to CFF examination.One-way ANOVA was used to perform above subgroup analysis.The correlations between CFF and F-VEP peak time,peak value,BCVA and mean visual filed defect(MD)were analyzed in order via Pearson correlation analysis.Results:he trichromatic values of red,green,and yellow in DON affected eyes were 21.83±9.03,23.66±10.21,24.09±10.77 Hz,respectively,which was significantly reduced compared with the HC group(t=-14.82,-14.22,-14.00;P<0.001).The subgroup analysis showed no significant difference between different antibody subtypes(P=0.914<0.848<0.604),whereas,a significant decrease of CFF trichromatic value was found in severe visual acuity impairment group(P<0.001).There was a significant difference in CFF-trichromatic values at different time points(P<0.001),to be specific,CFF fluctuated under 20Hz within 3 months after onset and tended to be stable around 24-28Hz.Correlation analysis showed that the peak time of F-VEP(r=-0.486,-0.515,-0.526;P<0.001),BVCA(r=-0.640,-0.659,-0.642;P<0.001),were negatively correlated with CFF trichromatic values,MD and CFF were positively correlated(r=0.486,0.453,0.476;P=0.003,0.006,0.004).Conclusions:A significant decrease of CFF value was found in DON-affected eyes,and it has a good correlation with BCVA,MD and latency of F-VEP,and can better reflect the impairment of visual function.