检索结果-南通市图书馆

Changes in physical activity and sleep following the COVID-19 pandemic on a university campus:Perception versus reality

引用

Sports Medicine and Health Science 2024年第3期6卷 246-251页

作者： Bryce T.Daniels Samantha Robinson Ivan Vargas Jamie I.Baum Erin K.Howie university of Arkansas FayettevilleARUnited States Rush university Medical Center ChicagoIllinoisUnited States1 university of Arkansas System Division of Agriculture FayettevilleARUnited States

It has been hypothesized that key lifestyle behaviors of physical activity and sleep worsened in response to the Coronavirus disease(COVID-19)***,there have been inconsistencies in findings of changes in these key lifestyle behaviors across populations likely due to the wide variety of assessment *** purpose of the study was to compare physical activity and sleep before and after the COVID-19 pandemic using accelerometers and self-reported behaviors.A longitudinal follow-up was conducted on students,faculty,and staff at a university campus in the United *** the periods before March 2020(covering the academic years of 2018–2019 or 2019–2020)and again in April–June 2021,participants completed surveys to evaluate their physical activity and sleep behaviors and wore an accelerometer.A total of 44 participants completed the survey at both timepoints and 32 completed accelerometer assessment at both ***-seven percent of participants reported a perceived decline in physical activity,while 30%reported a worsening in *** selfreported data,overall physical activity did not change,but there was a decrease in active transport(p<0.001)and increase in domestic physical activity(p?0.012).Sleep quality decreased as evidenced by an increase in Pittsburgh Sleep Quality Index scores(p?0.045).There were no changes in accelerometer measured physical activity or *** were no changes in physical or mental *** perceptions of physical activity declined from prior to the COVID-19 pandemic,there were no changes in device-measured physical activity,and changes in self-reported physical activity differed by domain.

关键词： Movement Longitudinal Measurement

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

No Reference Image Sharpness Assessment Based on Global Color Difference Variation

引用

Chinese Journal of Electronics 2024年第1期33卷 293-302页

作者： Chenyang SHI Yandan LIN School of Artificial Intelligence Anhui Polytechnic University School of Mechanical Engineering Anhui Polytechnic University Department of Light Sources and Illuminating Engineering Fudan University Academy for Engineering & Technology Fudan University

Image quality assessment(IQA) model is designed to measure the image quality in consistent with subjective ratings by computational models. In this research, a valid no reference IQA(NR-IQA) model for color image sharpness assessment is proposed based on local color difference map in a color space. In the proposed model, the absolute color difference variation and relative color difference variation are combined to evaluate sharpness in YIQ color space(a color coordinate system for the development of the United States color television system). The difference between sharpest and blurriest spot of an image is represented by the absolute color difference variation, and relative color difference variation expresses the variation in the image content. Extensive experiments are performed on five publicly available benchmark synthetic blur databases and two real blur databases, and the results prove that the proposed model work better than the other state-of-the-art and latest NR-IQA models for the prediction accuracy on blurry images. Besides, the model maintains the lowest computational complexity.

关键词： Image quality TV Image color analysis Databases Computational modeling Color Predictive models

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Adaptive coupled-sliding-variable-based finite-time control of composite formation for multi-robot systems

引用

Science China(Information Sciences) 2024年第10期67卷 244-260页

作者： Xinru MA Hengyu LI Jun LIU Yueying WANG Shaorong XIE Jun LUO School of Mechatronic Engineering and Automation Shanghai University School of Mathematics and Computer Application Technology Jining University School of Computer Science Shanghai University College of Mechanical and Vehicle Engineering Chongqing University

This paper focuses on the finite-time control(FTC) of the composite formation consensus(CFC)problems for multi-robot systems(MRSs). The CFC problems are firstly proposed for MRSs under the complex network topology of cooperative or cooperative-competitive networks. Regarding the problems of FTC and CFC on multiple Lagrange systems(MLSs), coupled sliding variables are introduced to deal with the robustness and consistent convergence. Then, the adaptive finite-time protocols are given based on the displacement approaches. With the premised FTC, tender-tracking methods are further developed for the problems of tracking information disparity. Stability analyses of those MLSs mentioned above are clarified with Lyapunov candidates considering the coupled sliding vectors, which provide new verification for tender-tracking systems. Under the given coupled-sliding-variable-based finite-time protocols, MLSs distributively adjust the local formation error to achieve global CFC and perform uniform convergence in time-varying tracking. Finally, simulation experiments are conducted while providing practical solutions for the theoretical results.

关键词： composite formation time-vary tracking information disparity tender-tracking finite-time control nonlinear robots complex networks symmetry consensus

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Multicolor circularly polarized phosphorescence of axially chiral binuclear platinum(Ⅱ) complexes

引用

Science China Chemistry 2024年第11期67卷 3757-3766页

作者： Jintong Song Rui Zeng Hui Xiao Hailiang Ni Zong-Xiang Xu Haifeng Xiang College of Chemistry and Materials Science Sichuan Normal University Department of Chemistry Southern University of Science and Technology College of Chemistry Sichuan University

D-A charge transfer, including through-bond charge transfer and through-space charge transfer between two different electron donors（D） and electron acceptors（A）, is a fundamental and powerful tool to tune the optical properties of organic dyes. Herein,we demonstrate a unique strategy to tune phosphorescence and circularly polarized luminescence properties of axially chiral binuclear Pt（Ⅱ） complexes through long-range charge transfer, even though these molecules have two totally identical segments on either side of the chiral core. The presence of axial chirality would break not only the symmetry of molecular structure and π-conjugation system but also the symmetry of charge distribution for long-range charge transfer. These binaphthyl-based Pt（Ⅱ）complexes bearing coordinated atoms far away from chiral axis exhibit no Pt-Pt interactions but colorful concentrationdependent phosphorescence with quantum yield up to 86.4% and could be applied as emitters in highly efficient solutionprocessed organic light-emitting diodes to achieve luminance, luminance efficiency, power efficiency, external quantum efficiency, and asymmetry factor up to 8.94 × 10～3cd m-2, 41.9 cd A-1, 18.8 lm W-1, 12.6% and 2.98 × 10-3, respectively. Therefore,the present work affords a new and simple way to utilize the inherently asymmetric advantage of chirality for the design of D-Abased organic dyes.

关键词： Pt(II) complexes organic light-emitting diodes circularly polarized phosphorescence axial chirality

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Fe3O4/Fe/FeS Tri-Heterojunction Node Spawning N-Carbon Nanotube Scaffold Structure for High-Performance Sodium-Ion Battery

引用

Energy & Environmental Materials 2024年第4期7卷 143-152页

作者： Yuan Liu Qing Lin Xiaocui Chen Xufeng Meng Baoxiu Hou Haiyan Liu Shuaihua Zhang Ningzhao Shang Zheng Wang Chaoyue Zhang Jianjun Song Xiaoxian Zhao Department of Chemistry College of Science Hebei Agricultural University College of Chemistry and Chemical Engineering Qingdao University College of Physics Qingdao University

The Fe-based anode of sodium-ion batteries attracts much attention due to the abundant source,low-cost,and high specific ***,the low electron and ion transfer rate,poor structural stability,and shuttle effect of NaS2intermediate restrain its further ***,the Fe3O4/Fe/FeS tri-heterojunction node spawned N-carbon nanotube scaffold structure（FHNCS） was designed using the modified MIL-88B（Fe） as a template followed by catalytic growth and sulfidation process.

关键词： anode core-shell heterojunction hollow structure sodium ion batteries

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

CToMP: a cycle-task-oriented memory protection scheme for unmanned systems

引用

Science China(Information Sciences) 2024年第6期67卷 399-417页

作者： Chengyan MA Ning XI Di LU Yebo FENG Jianfeng MA School of Cyber Engineering Xidian University School of Computer Science and Technology Xidian University Department of Computer and Information Science University of Oregon

Memory corruption attacks(MCAs) refer to malicious behaviors of system intruders that modify the contents of a memory location to disrupt the normal operation of computing systems, causing leakage of sensitive data or perturbations to ongoing processes. Unlike general-purpose systems, unmanned systems cannot deploy complete security protection schemes, due to their limitations in size, cost and *** in unmanned systems are particularly difficult to defend against. Furthermore, MCAs have diverse and unpredictable attack interfaces in unmanned systems, severely impacting digital and physical sectors. In this paper, we first generalize, model and taxonomize MCAs found in unmanned systems currently, laying the foundation for designing a portable and general defense approach. According to different attack mechanisms,we found that MCAs are mainly categorized into two types — return2libc and return2shellcode. To tackle return2libc attacks, we model the erratic operation of unmanned systems with cycles and then propose a cycle-task-oriented memory protection(CToMP) approach to protect control flows from tampering. To defend against return2shellcode attacks, we introduce a secure process stack with a randomized memory address by leveraging the memory pool to prevent Shellcode from being executed. Moreover, we discuss the mechanism by which CTo MP resists the return-oriented programming(ROP) attack, a novel variant of return2libc attacks. Finally, we implement CTo MP on CUAV V5+ with Ardupilot and Crazyflie. The evaluation and security analysis results demonstrate that the proposed approach CTo MP is resilient to various MCAs in unmanned systems with low footprints and system overhead.

关键词： unmanned system memory corruption attack memory protection system security randomized memory address

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Customized heat treatment process enabled excellent mechanical properties in wire arc additively manufactured Mg-RE-Zn-Zr alloys

引用

International Journal of Extreme Manufacturing 2024年第4期6卷 276-289页

作者： Dong Ma Chunjie Xu Shang Sui Yuanshen Qi Can Guo Zhongming Zhang Jun Tian Fanhong Zeng Sergei Remennik Dan Shechtman School of Materials Science and Engineering Xi'an University of TechnologyXi'anShaanxi 710048People's Republic of China Xi'an Shechtman Nobel Prize New Materials Institute Xi'an 710048People's Republic of China Xi'an Key Laboratory of Advanced Magnesium Alloy Additive Manufacturing and Precision Forming Xi'anShaanxi 710048People's Republic of China Department of Materials Science and Engineering and Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion Guangdong Technion—Israel Institute of TechnologyShantou 515063People's Republic of China MGM Nobel Prize New Materials Co. LtdTongchuan 727100People's Republic of China Department of Materials Science and Engineering Technion-Israel Institute of TechnologyHaifa 32000Israel Center for Nanoscience&Nanotechnology Hebrew University of JerusalemEdmond J.Safra CampusJerusalem 91904Israel

Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials,especially for alloys with complex phase constituents and heterogenous ***,the interrelated evolutions of different microstructure features make it difficult to establish optimal heat treatment ***,we proposed a method for customized heat treatment process exploration and establishment to overcome this challenge for such kind of alloys,and a wire arc additively manufactured(WAAM)Mg-Gd-Y-Zn-Zr alloy with layered heterostructure was used for feasibility *** this method,the optimal microstructures(fine grain,controllable amount of long period stacking ordered(LPSO)structure and nano-scaleβ'precipitates)and the corresponding customized heat treatment processes(520°C/30 min+200°C/48 h)were obtained to achieve a good combination of a high strength of 364 MPa and a considerable elongation of 6.2%,which surpassed those of other state-of-the-art WAAM-processed Mg ***,we evidenced that the favorable effect of the undeformed LPSO structures on the mechanical properties was emphasized only when the nano-scaleβ'precipitates were *** is believed that the findings promote the application of magnesium alloy workpieces and help to establish customized heat treatment processes for additively manufactured materials.

关键词： wire arc additive manufacturing heat treatment Mg-RE-Zn-Zr alloys LPSO structure mechanical properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The great catastrophe: causes of the Permo-Triassic marine mass extinction

引用

National Science Review 2024年第1期11卷 37-50页

作者： Paul B.Wignall David P.G.Bond School of Earth & Environment University of Leeds School of Environmental Sciences University of Hull

The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos(e.g. brachiopods, corals, bryozoans, foraminifers,ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ～55 kyr interval straddling the Permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. Decreased ocean ventilation coincides with rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high *** kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation(burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the Permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes(

关键词： ocean anoxia ocean acidification siltation productivity collapse volcanic winter

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Vascular medicine in the 21st century:Embracing comprehensive vasculature evaluation and multidisciplinary treatment

引用

World Journal of Clinical Cases 2024年第27期12卷 6032-6044页

作者： Yoram Chaiter Daniel Lyon Fink Yossy Machluf The Israeli Center for Emerging Technologies in Hospitals and Hospital-Based Health Technology Assessment Shamir(Assaf Harofeh)Medical CenterZerifin 7030100Israel Department of Pediatric Cardiology Unit HaEmek Medical CenterAfula 1834111Israel Shamir Research Institute University of HaifaKazerin 1290000Israel

The field of vascular medicine has undergone a profound transformation in the 21st century,transforming our approach to assessment and ***-sclerosis,a complex inflammatory disease that affects medium and large arteries,presents a major challenge for researchers and healthcare *** condition,characterized by arterial plaque formation and narrowing,poses sub-stantial challenges to vascular health at individual,national,and global *** repercussions are far-reaching,with clinical outcomes including ischemic heart disease,ischemic stroke,and peripheral arterial disease—conditions with esca-lating global *** detection of vascular changes caused by athero-sclerosis is crucial in preventing these conditions,reducing morbidity,and averting *** article underscored the imperative of adopting a holistic approach to grappling with the intricacies,trajectories,and ramifications of *** stresses the need for a thorough evaluation of the vasculature and the implementation of a multidisciplinary treatment *** consi-dering the entire vascular system,healthcare providers can explore avenues for prevention,early detection,and effective management of this condition,ultima-tely leading to improved patient *** discussed current practices and proposed new directions made possible by emerging diagnostic modalities and treatment ***,we considered healthcare expenditure,resour-ce allocation,and the transformative potential of new innovative treatments and technologies.

关键词： Vascular medicine Vasculature assessment Holistic approach Prevention avenues Healthcare transformation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advancements in synthetic and electrocatalytic exploitation of guest-host intercalated 2D materials

引用

Progress in Natural Science:Materials International 2024年第3期34卷 454-469页

作者： Qian Yang Kun Wang Meiling Zhang Feihong Du Jiayang Li Chen Zheng Jinyang Li School of Chemistry Southwest Jiaotong University Yibin Institute of Southwest Jiaotong university

The emergence and development of layered materials have shown great promise for many applications, especially in recent years, the effective modulation of the physicochemical properties of layered materials by intercalation chemistry has led to great potential in material design. In this paper, we review the reaction mechanisms of different guest species(metal atoms/ions, organic molecules/ions, inorganic molecules and inorganic ions)intercalated into the host layered materials as well as the recent progress. It is also reviewed that layered intercalated materials with controllable structure and tunable physicochemical properties can be prepared through the occurrence of interactions between different subjects and guests. The specific applications of intercalation chemistry in the field of electrocatalysis, such as the hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction and other electrocatalytic reactions, are then discussed, with emphasis on the mechanism of the improved catalytic activity and stability of the layered materials after guest intercalation.

关键词： Electrocatalysis Guest species Intercalation chemistry Layered materials

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：