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Lipschitz-continuity of Spherically Convex Functions

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Acta Mathematica Sinica,English Series 2023年第2期39卷 363-374页

作者： Yin ZHANG Qi Guo Department of Mathematics Suzhou University of Science and TechnologySuzhou215009China

In this article,some basic and important properties of spherically convex functions,such as the Lipschitz-continuity,are investigated.It is shown that,under a weaker condition,every family of spherically convex functions is equi-Lipschitzian on each closed spherically convex subset contained in the relative interior of their common domain,and from which a powerful result is derived:the pointwise convergence of a sequence of spherically convex functions implies its uniform convergence on each closed spherically convex subset contained in the relative interior of their common domain.

关键词： Spherically convex set spherically convex function Lipschitz-continuity uniform convergence

Predicting Supermassive Black Hole Mass with Machine Learning Methods

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Research in Astronomy and Astrophysics 2022年第8期22卷 182-190页

作者： Yi He Qi Guo Shi Shao Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China

It is crucial to measure the mass of supermassive black holes(SMBHs)in understanding the co-evolution between the SMBHs and their host galaxies.Previous methods usually require spectral data which are expensive to obtain.We use the AGN catalog from the Sloan Digital Sky Survey project Data Release 7(DR7)to investigate the correlations between SMBH mass and their host galaxy properties.We apply the machine learning algorithms,such as Lasso regression,to establish the correlation between the SMBH mass and various photometric properties of their host galaxies.We find an empirical formula that can predict the SMBH mass according to galaxy luminosity,colors,surface brightness,and concentration.The root-mean-square error is 0.5 dex,comparable to the intrinsic scatter in SMBH mass measurements.The 1σscatter in the relation between the SMBH mass and the combined galaxy properties relation is 0.48 dex,smaller than the scatter in the SMBH mass versus galaxy stellar mass relation.This relation could be used to study the SMBH mass function and the AGN duty cycles in the future.

关键词： (galaxies:)quasars:supermassive black holes galaxies:evolution methods:data analysis

New materials and designs for 2D-based infrared photodetectors

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Nano Research 2023年第2期16卷 3074-3103页

作者： Huitian guo Weihong qi State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Shandong Laboratory of Yantai Advanced Materials and Green Manufacturing Yantai 264006China

Infrared photodetectors have attracted much attention considering their wide civil and military applications.Two-dimensional(2D)materials offer new opportunities for the development of costless,high-level integration and high-performance infrared photodetectors.With the advent of a broad investigation of infrared photodetectors based on graphene and transition metal chalcogenides(TMDs)exhibiting unique properties in recent decades,research on the better performance of 2D-based infrared photodetectors has been extended to a larger scale,including explorations of new materials and artificial structure designs.In this review,after a brief background introduction,some major working mechanisms,including the photovoltaic effect,photoconductive effect,photogating effect,photothermoelectric effect and bolometric effect,are briefly offered.Then,the discussion mainly focuses on the recent progress of three categories of 2D materials beyond graphene and TMDs.Noble transition metal dichalcogenides,black phosphorus and arsenic black phosphorous and 2D ternary compounds are great examples of explorations of mid-wavelength or even long-wavelength 2D infrared photodetectors.Then,four types of rational structure designs,including type-II band alignments,photogating-enhanced designs,surface plasmon designs and ferroelectric-enhanced designs,are discussed to further enhance the performance via diverse mechanisms,which involve the narrower-bandgap-induced interlayer exciton transition,gate modulation by trapped carriers,surface plasmon polaritons and ferroelectric polarization in sequence.Furthermore,applications including imaging,flexible devices and on-chip integration for 2D-based infrared photodetectors are introduced.Finally,a summary of the state-of-the-art research status and personal discussion on the challenges are delivered.

关键词： two-dimensional(2D)materials infrared photodetectors noble transition metal dichalcogenides black phosphorus layered ternary compounds structure designs

Atrial fibrillation and frailty

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Journal of Geriatric Cardiology 2020年第2期17卷 105-109页

作者： Qi Guo Xin DU Chang-Sheng MA Department of Cardiology Beijing Anzhen HospitalCapital Medical UniversityNational Clinical Research Center for Cardiovascular DiseasesBeijing Advanced Innovation Center for Big Data-Based Precision Medicine for Cardiovascular Diseases

Both the prevalence of atrial fibrillation(AF)and frailty are increasing with age,and they often occur simultaneously,leading them to become the central concerns in this aging society.The incidence of frailty in patients with AF is highly variable,ranging from 4.4%to 75.4%,depending on different evaluating instruments used.Moreover,the incidence of frailty among patients with AF is on the rise,which indicated that patients with AF are more prone to frailty compared to patients without AF.The relationship between AF and frailty is complicated.Frailty elevates the risk of stroke and mortality in AF patients and is also associated with longer hospitalizations.On the other hand,it may reduce the appropriate anticoagulation in AF patients.However,the evidence of the effects of frailty on anti-arrhythmic and interventional therapy in patients with AF is scarce.Frailty affects both the management and the prognosis of AF in the geriatric population.Vice versa,AF could worsen the frail state and may represent a marker of frailty.However,there are still questions need to be resolved,for example,the impact of frailty on the interventional therapy of patients with AF.Therefore,the geriatric assessment of frailty should be considered when planning individualized management of AF in older patients.

关键词： Atrial fibrillation Epidemiology Frailty Management Prognosis

The Halo Concentration and Mass Relation Traced by Satellite Galaxies

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Research in Astronomy and Astrophysics 2022年第12期22卷 292-298页

作者： qing Gu Qi Guo Tianchi Zhang Wenting Wang Quan guo Liang Gao Key Laboratory for Computational Astrophysics National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Beijing Planetarium Beijing Academy of Science and TechnologyBeijing 100044China Department of Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai 200240China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Institute of Computational Cosmology Department of PhysicsUniversity of DurhamScience LaboratoriesSouth RoadDurham DH13LEUK

We study the relation between halo concentration and mass(c-M relation) using galaxy catalogs of the Seventh and Eighth Data Releases of the Sloan Digital Sky Survey(SDSS DR7 and DR8). Assuming that the satellite galaxies follow the distribution of dark matter, we derive the halo concentration by fitting the satellite radial profile with a Nararro Frank and White(NFW) format. The derived c-M relation covers a wide halo mass range from10^(11.6)to 10^(14.1)M_(⊙). We confirm the anti-correlation between the halo mass and concentration as predicted in cosmological simulations. Our results are in good agreement with those derived using galaxy dynamics and gravitational lensing for halos of 10^(11.6)– 10^(12.9)M_(⊙), while they are slightly lower for halos of 10^(12.9)– 10^(14.1)M_(⊙).This is because blue satellite galaxies are less concentrated, especially in the inner regions. Instead of using all satellite galaxies, red satellites could be better tracers of the underlying dark matter distribution in galaxy groups.

关键词： galaxies:halos galaxies:evolution galaxies:abundances

Review on microbial metabolomics of probiotics and pathogens:Methodologies and applications

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BIOCELL 2023年第1期47卷 91-107页

作者： XIN MENG XUE LI LIANRONG YANG RUI YIN LEHUI qi Qi Guo School of Pharmacy Heilongjiang University of Chinese MedicineHarbin150040China

In recent years,microbial metabolomics,a new field that has attracted wide attention,provides a map of metabolic pathways and clarifies the interaction mechanism between microorganisms and hosts.Many microorganisms are found in the human intestine,oral cavity,vagina,etc.Probiotics could maintain the good health of the host,while pathogens and an imbalance of bacterial flora lead to a series of diseases of the body and mind.Metabolomics is a science for qualitative and quantitative analysis of all metabolites in an organism or biological system,which could provide key information to understand the related metabolic pathways and associated changes.This approach analyzes the final products of cellular regulatory processes,the level of which can be regarded as the ultimate response of the biological system to genetic or environmental changes.Microbial metabolomics has been widely used in different research fields,such as microbial phenotypic classification,mutant screening,metabolic pathways,microbial metabolic engineering,fermentation engineering monitoring and optimization,microbial environmental pollution,and so on.However,there are only a few reviews on microbial metabolomics of probiotics and pathogens.This review summarizes the main methodologies,including sample preparation,identification of metabolites,data processing,and analysis.Recent applications in microbial metabolomics of probiotics and pathogens are also described.This paper first summarized the research progress and application of microbial metabolomics from two aspects:probiotics and pathogenic bacteria.Probiotics and pathogenic bacteria do not exist independently most of the time;hence,these were reviewed in the research field of coexistence of probiotics and pathogenic bacteria,which was subdivided into important microbial research fields closely related to human health,including the human gut,oral cavity,food,and nutrition-related microorganisms.Then,the main problems and trends associated with microbial metabolomics are discussed.

关键词： Probiotics Pathogens Microbial metabolomics Methodology Application

Multiplicity of Periodic Bouncing Solutions for Sublinear Damped Variation Systems via Nonsmooth Variational Methods

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Acta Mathematica Sinica,English Series 2023年第7期39卷 1332-1350页

作者： Si qi WANG Fei guo School of Mathematics Tianjin UniversityTianjin 300354China Tianjin Key Laboratory of Brain-Inspired Intelligence Technology Tianjin 300354China

Two results about the multiplicity of nontrivial periodic bouncing solutions for sublinear damped vibration systems-x=g(t)x+f(t,x) are obtained via the Generalized Nonsmooth Saddle Point Theorem and a technique established by Wu Xian and Wang Shaomin.Both of them imply the condition "f≥0" required in some previous papers can be weakened,furthermore,one of them also implies the condition about ■F(t,x)/■t required in some previous papers,such as "|■F(t,x)/■t|=σ_(0)F(t,x)" and "|■F(t,x)/■t|≤C(1+F(t,x))", is unnecessary,where F(t,x):=∫_(0)~xf(t,x)ds,and σ_(0),C are positive constants.

关键词： Damped vibration systems generalized Nonsmooth Saddle Point Theorem sublinear conditions periodic bouncing solutions multiplicity

Rescue to the Curse of universality

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Science China(Information Sciences) 2023年第9期66卷 134-150页

作者： Yongwei ZHAO Zidong DU Qi Guo Zhiwei XU Yunji CHEN State Key Lab of Processors Institute of Computing Technology Chinese Academy of Sciences Beijing Academy of Artificial Intelligence University of Chinese Academy of Sciences

From the very beginning of computers, universality has been the core focus in the building of computing machines, such as the universal Turing machine, von Neumann architecture, random-access machines, and universal circuits. Academia has taken universality as the primary principle ever since. However,the Curse of universality, implied from L.G.Valiant’s Universal Circuit, states that computers based on logic circuits cannot be both universal and efficient, as the cost of universality is Ω(n log2n). Though the Curse has been hidden by the rapid advancement of semiconductor technologies, it has been wielding its effects noticeably in recent years. Due to the ending of Dennard scaling and Moore’s law, general-purpose processors leave less room for improvement. Therefore, domain-specific architectures(DSAs), such as deep learning processors, have been exploding, leading to the new golden age of computer architectures. For DSAs, universality is traded off for optimal efficiency. However, we predict that universality will once again be a major concern for post-golden-age computers. In this paper, we discuss how much universality could an efficient computer keep. As a rescue to the Curse, we define and discuss quasi-universal architectures. Quasi-universal architectures can solve any computable problem and are efficient for a wide range of problems. The proposed Recursive-Encapsulated(RENC) architecture achieves maximal universality while keeping optimal efficiency as found in specialized architectures. The discovery of RENCsuggests that current golden-age architectures are not Pareto optimal.

关键词： universality general-purpose architecture specialized architecture deep learning processor universal circuit

Tuning Charge Transport of Oligopeptide Junctions via Interfacial Amino Acids

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Chinese Journal of Chemistry 2023年第17期41卷 2113-2118页

作者： Jiaxin guo Pan qi Yongkang Zhang Cunlan guo College of Chemistry and Molecular Sciences Wuhan UniversityWuhanHubei 430072China

Comprehensive Summary,The charge transport through peptides can imitate the corresponding processes in more complicated proteins,enabling us to develop high-performance bioelectronic devices and to understand the mechanisms of biomolecular recognition and information transfer.While charge transport modulation through individual peptides has been achieved via various covalent strategies,the intermolecular modulation is still very challenging,which may capture the charge transport between proteins.To tackle this challenge,we used well-defined self-assembled monolayers(SAMs)of oligopeptides as a model to imitate the interface of proteins and explored an interfacial amino acid strategy for charge transport modulation.We showed that non-covalently interfaced charged amino acids(e.g.,arginine)effectively attenuated the charge transport of glutamic acid terminated polyglycine peptide SAMs.By analyzing the relationship of the charge transport with the molecular frontier orbital relative to the Fermi energy level of the electrode,the molecule-electrodes coupling(Γ),and the trends in skewness and kurtosis with voltage and the dielectric constant(εr),we showed that the attenuation was from the decreasedΓand the reduced polarizability.We present an efficient strategy to modulate the charge transport of oligopeptide-SAM junctions by intermolecular interactions,which will advance our understanding of charge transport in biological systems and facilitate developing future electronics.

关键词： Charge transport modulation Molecular electronics Molecular junctions Interfaces Weak intermolecular interactions