How to Coadd Images.Ⅱ.Anti-aliasing and PSF Deconvolution

We have developed a novel method for co-adding multiple under-sampled images that combines the iteratively reweighted least squares and divide-and-conquer algorithms.Our approach not only allows for the anti-aliasing of the images but also enables Point-Spread Function(PSF)deconvolution,resulting in enhanced restoration of extended sources,the highest peak signal-to-noise ratio,and reduced ringing artefacts.To test our method,we conducted numerical simulations that replicated observation runs of the China Space Station Telescope/the VLT Survey Telescope(VST)and compared our results to those obtained using previous algorithms.The simulation showed that our method outperforms previous approaches in several ways,such as restoring the profile of extended sources and minimizing ringing artefacts.Additionally,because our method relies on the inherent advantages of least squares fitting,it is more versatile and does not depend on the local uniformity hypothesis for the PSF.However,the new method consumes much more computation than the other approaches.

Coupling effects of temperature,confining pressure,and pore pressure on permeability and average pore size of Longmaxi shale

The evolution due to temperature and pressure of shale reservoir permeability affects the productivity evaluation and development decision of shale gas reservoirs,which is very important for the exploration and development of unconventional gas reservoirs.This study analyzed the coupling effects of temperature(25,50,and 75°C),effective stress(15 and 30 MPa),and pore pressure(0.5,2.0,4.0,and 8.0 MPa)on the permeability of the shale sample in the Longmaxi Formation.As the temperature and pressure increased,the apparent permeability exhibited a downward trend,and the absolute permeability decreased with the rise of temperature or effective stress.An in‐depth analysis of the gas slippage factors under the conditions of different temperature and pressure was conducted to evaluate the trend of the average pore width with temperature and pressure.The results were then verified by scanning electron microscopy(SEM).The results provide new insights into evaluating the permeability of the Longmaxi shale and can be used to enhance the gas recovery rate of deep shale gas reservoirs.

Anisotropic strength,deformation and failure of gneiss granite under high stress and temperature coupled true triaxial compression

The anisotropic mechanical behavior of rocks under high-stress and high-temperature coupled conditions is crucial for analyzing the stability of surrounding rocks in deep underground engineering.This paper is devoted to studying the anisotropic strength,deformation and failure behavior of gneiss granite from the deep boreholes of a railway tunnel that suffers from high tectonic stress and ground temperature in the eastern tectonic knot in the Tibet Plateau.High-temperature true triaxial compression tests are performed on the samples using a self-developed testing device with five different loading directions and three temperature values that are representative of the geological conditions of the deep underground tunnels in the region.Effect of temperature and loading direction on the strength,elastic modulus,Poisson’s ratio,and failure mode are analyzed.The method for quantitative identification of anisotropic failure is also proposed.The anisotropic mechanical behaviors of the gneiss granite are very sensitive to the changes in loading direction and temperature under true triaxial compression,and the high temperature seems to weaken the inherent anisotropy and stress-induced deformation anisotropy.The strength and deformation show obvious thermal degradation at 200℃due to the weakening of friction between failure surfaces and the transition of the failure pattern in rock grains.In the range of 25℃ 200℃,the failure is mainly governed by the loading direction due to the inherent anisotropy.This study is helpful to the in-depth understanding of the thermal-mechanical behavior of anisotropic rocks in deep underground projects.

Overview of the Third Global Forum

Computer science continues to grow at a rapid pace,raising the issue of how universities can best adapt to this trend.At the third Global Forum on the Development of Computer Science(GFDCS),five heads of departments of computer science from Asia,Europe,and North America came together to exchange ideas under the theme Challenges and Opportunities of Computer Science in the New Era.Through the discussions,a number of new challenges were explored,including how to meet the growing demand for computer science education,how to manage increased teaching loads,how to foster collaboration between computer science and other disciplines,how to raise ethical awareness,and how to support new“transdisciplinary”modes of education and research.At the same time,there was a consensus on the need to strengthen the role of computer science in other departments,the importance of industrial collaboration,and the need for more scalable approaches to teaching.The evolving role of computer science within the context of broader science was also discussed.

Assessing current stocks and future sequestration potential of forest biomass carbon in Daqing Mountain Nature Reserve of Inner Mongolia, China

Assessment of regional forest carbon stocks and underlying controls is critical for guiding forest management in the context of carbon sequestration. We investigated the variations in tree biomass carbon stocks relating to forest types, and estimated the total tree biomass carbon stocks and projected gains through natural stand development by 2020 and 2050 in the Daqing Mountain Nature Reserve based on Category II data of the Forest Inventory of Inner Mongolia for the period ending 2008. Over a total area of 388,577 ha,this nature reserve currently stores an estimated 2221 Gg C in tree aboveground biomass alone, with potential to grow by more than 30 % to reach 2938 Gg C by 2020 and nearly double to 4092 Gg C by 2050 through natural development of the existing forest stands. The tree biomass carbon density and potential gain in tree biomass carbon stocks vary markedly among forest types and with stand development.The variations in the potential change of tree biomass carbon density for the periods 2008–2020 and 2008–2050 among forest types partly reflect the varying relationships of tree biomass carbon density with stand age for different tree species, and partly are attributable to variations in the stand age structure among different forest types. Of the major forest types, the ranking of projected changes in tree biomass carbon density are not consistent with variations in the relationship between tree biomass carbon density and stand age, neither are they explainable by variations in stand age structures, implying the interactive effect between forest type and stand dynamics on temporal changes in tree biomass carbon density. Birch rank highest for future biomass carbon sequestration because of its dominance in cover area and better age structure for potential gain in tree biomass carbon stocks. Poplar and larch were out-performers compared to other forest types given their greater contribution to total tree biomass carbon stocks relative to their distributional areas. Findings in this study illustrate that protection and proper management of under-aged forests can deliver marked gains in biomass carbon sequestration. This is of great importance to policy-makers as well as to scientific communities in seeking effective solutions for adaptive forest management and mitigation of anthropogenic greenhouse gases emissions using forest ecosystems.

Unveiling the Underlying Mechanism of Transition Metal Atoms Anchored Square Tetracyanoquinodimethane Monolayers as Electrocatalysts for N_(2) Fixation

We for the first time systematically studied the structures and electrochemical nitrogen reduction reaction properties of two-dimensional single transition-metal anchored square tetracyanoquinodimethane monolayers(labeled as:TM-sTCNQ,TM=3d,4d,5d series transition metals)by employing density functional theory method.Through highthroughput screenings and full reaction path researches,two promising electrochemical nitrogen reduction reaction catalysts Nb-sTCNQ and MosTCNQ have been obtained.The nitrogen reduction reaction onset potential on Nb-sTCNQ is as low as−0.48 V.Furthermore,the Nb-sTCNQ catalyst can quickly desorb NH3 produced with a free energy of 0.65 eV,giving Nb-sTCNQ excellent catalytic cycle performance.The high catalytic activity of the two materials might be attributed to the effective charge transfer between the active center and adsorbed N_(2),which enables the active center to adsorb and activate inert N_(2) molecules well,and the reduction processes require small energy input(i.e.,the maximum free energy changes are small).This work provides insights for finding highly efficient,stable,and low-cost nitrogen reduction reaction electrocatalysts.We hope our results can promote further experimental and theoretical research of this field.

Wernicke encephalopathy Clinical presentation and MR images in two nonalcoholic patients

The aim of the present study was to investigate the importance of and correlation between clinical presentations and magnetic resonance imaging （MRI） of two different cases of nonalcoholic Wernicke encephalopathy. Case l ： A 63-year-old man with a diagnosis of incomplete mechanical intestinal obstruction. His abdominal symptoms were improved by gastrointestinal decompression, but blurred vision, hypoacusis, dizziness, and unsteady gait were noted. His illness deteriorated to confusion on day seven. MRI showed hyperintense lesions in the medial thalami, tectum of the midbrain, and the periaqueduct region on T2- and diffusion-weighted images. Thiamine therapy was commenced immediately with good results. Case 2： A 22-year-old woman was admitted for sudden-onset confabulation and unsteady gait after hyperemesis gravidarum. She had no history of alcohol or any medication. Brain MRI was normal. The patient experienced relief after Vitamin B1 treatment. These results suggest that brain MRI can define characteristic abnormalities in Wernicke encephalopathy, and that diffusion-weighted imaging may improve the diagnosis sensitivity. In addition, the MRI images may be correlated to the clinical stage and severity of the disease. Nevertheless, the clinical features are essential for correct diagnosis.

The Chromatic Point-spread Function of Weak Lensing Measurement in the Chinese Space Station Survey Telescope

Weak gravitational lensing is a powerful tool in modern cosmology.To accurately measure the weak lensing signal,one has to control the systematic bias on a small level.One of the most difficult problems is how to correct the smearing effect of the Point-Spread Function(PSF)on the shape of the galaxies.The chromaticity of PSF for a broad-band observation can lead to new subtle effects.Since the PSF is wavelength-dependent and the spectrum energy distributions between stars and galaxies are different,the effective PSF measured from the star images will be different from those that smear the galaxies.Such a bias is called color bias.We estimate it in the optical bands of the Chinese Space Station Survey Telescope from simulated PSFs,and show the dependence on the color and redshift of the galaxies.Moreover,due to the spatial variation of spectra over the galaxy image,another higher-order bias exists:color gradient bias.Our results show that both color bias and color gradient bias are generally below 0.1%in CSST.Only for small-size galaxies,one needs to be careful about the color gradient bias in the weak lensing analysis using CSST data.

Theoretical Analysis of Random Scattering Induced by Microlensing

Theoretical investigations into the deflection angle caused by microlenses offer a direct path to uncovering principles of the cosmological microlensing effect.This work specifically concentrates on the the probability density function(PDF)of the light deflection angle induced by microlenses.We have made several significant improvements to the widely used formula from Katz et al.First,we update the coefficient from 3.05 to 1.454,resulting in a better fit between the theoretical PDF and our simulation results.Second,we developed an elegant fitting formula for the PDF that can replace its integral representation within a certain accuracy,which is numerically divergent unless arbitrary upper limits are chosen.Third,to facilitate further theoretical work in this area,we have identified a more suitable Gaussian approximation for the fitting formula.

Forecast of Observing Time Delay of Strongly Lensed Quasars with the Muztagh-Ata 1.93m Telescope

As a completely independent method,the measurement of time delay of strongly lensed quasars(TDSL)are crucial to resolve the Hubble tension.Extensive monitoring is required but so far limited to a small sample of strongly lensed quasars.Together with several partner institutes,Beijing Normal University is constructing a 1.93 m reflector telescope at the Muztagh-Ata site in west China,which has the world class observing conditions with median seeing of 082 and median sky brightness of 21.74 mag arcsec-2 in V-band during the dark time.The telescope will be equipped with both a three-channel imager/photometer which covers 3500–11,000?wavelength band,and a low-medium resolution(λ/δλ=500/2000/7500)spectrograph.In this paper,we investigate the capability of the Muztagh-Ata 1.93 m telescope in measuring time delays of strongly lensed quasars.We generate mock strongly lensed quasar systems and light curves with microlensing effects based on five known strongly lensed quasars,i.e.,RX J1131-1231,HE 0435-1223,PG 1115+080,WFI 2033-4723 and SDSS 1206+4332.In particular,RX J1131-1231 is generated based on the lens modeling results of Suyu et al.Due to the lack of enough information,the other four systems are calculated by a simple analytical approximation.According to simulations,for RX J1131-like systems(wide variation in time delay between images)the TDSL measurement can be achieved with the precision aboutΔt=0.5 day with four seasons campaign length and 1 day cadence.This accuracy is comparable to the up-coming TDCOSMO project.And it would be better when the campaign length keeps longer and with high cadence.As a result,the capability of the Muztagh-Ata 1.93 m telescope allows it to join the network of TDSL observatories.It will enrich the database for strongly lensed quasar observations and make more precise measurements of time delays,especially considering the unique coordinate of the site.

物理化学课程思政教学设计与实践

推进专业课程与思政教育融合是落实高校立德树人的根本。物理化学作为化学类核心专业基础课程,对学生的培养起着至关重要的作用。依据课程思政内涵,结合物理化学课程教学目标,从学科发展史、科学家简介、经典理论和方法、学科交叉、科学发展前沿以及物理化学在生产生活中的应用等6个方面挖掘梳理课程蕴含的思政教育要点,并进行相应的教学设计。同时给出了课程思政教学实践模式和评价方法。

Do Antineoplastic Drugs Play an Additional Role in the Progression of Non-Compaction Cardiomyopathy? A Case Report

Non-compaction cardiomyopathy is a rare form of cardiomyopathy;its most common clinical manifestations are heart failure (HF), ventricular arrhythmia, thromboembolism, and sudden cardiac death. We report a rare case of a 63-year-old man with chest tightness, worsening lower leg edema, dyspnea, and decreased exercise tolerance. He had a medical history of gastric cancer treated with subtotal gastrectomy and post-operative chemotherapy with paclitaxel and fluorouracil three years ago. At that time, he was diagnosed with non-compaction cardiomyopathy, and the thickened and reticulated trabecular muscle was exclusively confined to left ventricular apex. Five months ago, he was admitted to our hospital with heart failure and treated for dilated cardiomyopathy, echocardiography revealed severe trabecular noncompact myocardium in both ventricles, which was confirmed by cardiac magnetic resonance imaging (CMR). It is generally accepted that non-compacted myocardium forms in the early embryonic stage, which raises a question in our case whether acquired factors, such as antineoplastic drugs, potentially accelerate the pathological progression of non-compaction cardiomyopathy. Considering there are disparities between current screening tools such as echocardiography and CMR regarding diagnostic criteria, multi-detector CT may be an alternative examination method that could provide a new perspective for diagnosis.

Genome-wide prediction in a hybrid maize population adapted to Northwest China

Genome-wide prediction is a promising approach to boost selection gain in hybrid breeding.Our main objective was to evaluate the potential and limits of genome-wide prediction to identify superior hybrid combinations adapted to Northwest China.A total of 490 hybrids derived from crosses among 119 inbred lines from the Shaan A and Shaan B heterotic pattern were used for genome-wide prediction of ten agronomic traits.We tested eight different statistical prediction models considering additive(A)effects and in addition evaluated the impact of dominance(D)and epistasis(E)on the prediction ability.Employing five-fold cross validation,we show that the average prediction ability ranged from 0.386 to 0.794 across traits and models.Six parametric methods,i.e.ridge regression,LASSO,Elastic Net,Bayes B,Bayes C and reproducing kernel Hilbert space(RKHS)approach,displayed a very similar prediction ability for each trait and two non-parametric methods(random forest and support vector machine)had a higher prediction performance for the trait rind penetrometer resistance of the third internode above ground(RPR_TIAG).The models of A+D RKHS and A+D+E RKHS were slightly better for predicting traits with a relatively high non-additive variance.Integrating trait-specific markers into the A+D RKHS model improved the prediction ability of grain yield by 3%,from 0.528 to 0.558.Of all 6328 potential hybrids,selection of the top 44 hybrids would lead to a 6%increase in grain yield compared with Zhengdan 958,a commercially successful hybrid variety.In conclusion,our results substantiate the value of genome-wide prediction for hybrid breeding and suggest dozens of promising single crosses for developing high-yielding hybrids for Northwest China.

Association of a single nucleotide polymorphism at 6q25.1, rs2046210, with endometrial cancer risk among Chinese women

A recent genome-wide association study identified a new susceptibility locus for breast cancer, rs2046210, which is a single nucleotide polymorphism (SNP) located upstream of the estrogen receptor α (ESR1) gene on chromosome 6q25.1. Given that endometrial cancer shares many risk factors with breast cancer and both are related to estrogen exposure and that rs2046210 is in close proximity to the ESR1 gene, we evaluated the association of SNP rs2046210 with endometrial cancer risk among 953 cases and 947 controls in a population-based, case-control study conducted in Shanghai, China. Logistic regression models were used to derive odds ratios (ORs) and 95% confidence intervals (95% CIs) after adjusting for potential confounders. We found that the A allele of rs2046210, linked to an increased risk of breast cancer, was associated with increased but not statistically significant risk of endometrial cancer (OR = 1.16, 95% CI = 0.96-1.41 for the GA and AA genotypes compared with the GG genotype); the association was stronger among post-menopausal women (OR = 1.28, 95% CI = 1.00-1.65). The association tended to be stronger among women with higher or longer estrogen exposure than among women with relatively lower or shorter exposure to estrogen. Our study suggests that rs2046210 may play a role in the etiology of endometrial cancer. Additional studies are needed to confirm our findings.

Overview of the Second Global Forum on Development of Computer Science

To explore the nature of computer science and promote the development of the computer science discipline,Tsinghua University organized a global forum during the 60th anniversary of the Department of Computer Science and Technology at Tsinghua.The forum aimed to bring together leaders of the top computer science departments in the world to discuss the fundamentals of computer science,improve the quality of talent cultivation,and promote the development of the global computer science discipline.

Identification of a male-specific region(MSR)in Spinacia oleracea

Dioecy,the presence of male and female individual,has evolved independently from hermaphroditism in multiple flowering plant lineages.Spinach,an important leafy vegetable crop worldwide,is a dioecious species with an XY sex-determination system.Although some markers that are fully linked to male-determination locus were identified,the male-specific region(MSR)remained unclear.In this research,five male individuals and five female lines were resequenced to identify the male-specific region.We identified a region(∼21 kb)on chromosome 4(putative sex chromosome)where the five females had a low reads coverage,while the five males had high coverage.A KASP marker,SponR,developed from a single nucleotide polymorphism(SNP)closely linked to the MSR was co-segregating with the sex determination gene in the population of 958 individuals,suggesting that the MSR might be specifically present in male spinach plants.

The Physiological Basis of Heterosis for Potassium Uptake of Hybrid Millet

Hybrid millet Zhang and its parental cultivars were studied for their potassium (K) uptake and accumulation characteristics and related physiological mechanisms. Hydroponic culture was performed with two K levels (i.e., high and low) set up. At high K level, hybrid millet showed heterobeltiosis in K accumulation and leaf K content, and it also had higher H+-ATPase activity, respiration rate, root oxidant activity and root K+ influx rate than its parental cultivars. All these lay the physiological foundation of heterosis for potassium uptake of hybrid millet. At low K level, the hybrid millet had a lower H+-ATPase activity and a higher K efflux rate than its parental cultivars, thus heterobeltiosis in K accumulation or leaf K content was not observed. Therefore, high level K fertilizer application is recommended for hybrid millet cultivation as it is favorable for hybrid millet to display heterosis in K uptake and K accumulation.

An Open Invitation to Join the International Brugada Electrocardiographic Indices Registry

Background:The Brugada Electrocardiographic Indices Registry is a comprehensive data registry composed of patients with Brugada patterns on the electrocardiogram(ECG).The aim is to test the hypotheses that(i)ECG indices combining both depolarization and repolarization abnormalities can better predict spontaneous ventricular arrhythmias than existing ECG markers in Brugada syndrome and(ii)that serial ECG measurements will provide additional information for risk stratifi cation,especially in asymptomatic patients.Methods:Patients with both Brugada pattern ECGs and Brugada syndrome are eligible for inclusion in this registry.Baseline characteristics and ECG variables refl ecting depolarization and repolarization will be determined.The primary outcome is spontaneous ventricular tachycardia/ventricular fi brillation or sudden cardiac death.Secondary outcomes are inducible ventricular tachycardia/ventricular fi brillation and syncope.Results:As of November 15,2019,39 investigators from 32 cities in 18 countries had joined this registry.As of December 15,2019,1383 cases had been enrolled.Conclusions:The Brugada Electrocardiographic Indices Registry will evaluate the disease life course,risk factors,and prognosis in a large series of Brugada patients.It will therefore provide insights for improving risk stratification.

Behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations on J-TEXT tokamak

The behavior of multiple modes before and during minor disruption with the external resonant magnetic perturbations(RMPs)has been studied on a J-TEXT tokamak.The main component of RMPs is m/n=2/1,where m and n are the numbers of the poloidal and toroidal modes,respectively.During the mode-locking caused by RMPs,it is found that before a minor or a major disruption(if there is no minor disruption),strong oscillations in both electron temperature and density occur if the edge safety factor q_(a)>3.The analysis shows that the oscillations are caused by the m/n=3/1 mode.In addition,using the ECE,Mirnov coils and 2D electron cyclotron emission imaging diagnostic systems,it is found that a thermal collapse occurs on the inner side of the 2/1magnetic island during the minor disruption,and before the collapse,a 3/2 island increases,after the collapse,the 3/2 island may disappear.Moreover,the study also shows that these 3/1,2/1 and 3/2modes play roles in the thermal collapse of disruptions.

Running with Face Masks or Respirators Can Be Detrimental to the Respiratory and Cardiovascular Systems

Since the fi rst cases of coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coro-navirus 2(SARS-CoV-2)were reported at the end of 2019,this infection has spread around the globe,becoming a pandemic.The use of face masks and respirators is an important public health measure to reduce or prevent transmission of SARS-CoV-2.Here we discuss the hypothetical mechanisms by which exercise with face masks or respirators can induce detrimental effects on the cardiovascular system,potentially explaining adverse events such as cardiac arrhythmias and spontaneous pneumothorax.Although sudden death associated with the wearing of a face mask during running is a rare event,the risk is higher especially in those with existing cardiac comorbidities.In such cases,a mask designed specifi cally for runners with no or few side effects of oxygen defi ciency should be considered instead.