67 research outputs found

    Extremal problems for disjoint graphs

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    For a simple graph FF, let EX(n,F)\mathrm{EX}(n, F) and EXsp(n,F)\mathrm{EX_{sp}}(n,F) be the set of graphs with the maximum number of edges and the set of graphs with the maximum spectral radius in an nn-vertex graph without any copy of the graph FF, respectively. Let FF be a graph with ex(n,F)=e(Tn,r)+O(1)\mathrm{ex}(n,F)=e(T_{n,r})+O(1). In this paper, we show that EXsp(n,kF)⊆EX(n,kF)\mathrm{EX_{sp}}(n,kF)\subseteq \mathrm{EX}(n,kF) for sufficiently large nn. This generalizes a result of Wang, Kang and Xue [J. Comb. Theory, Ser. B, 159(2023) 20-41]. We also determine the extremal graphs of kFkF in term of the extremal graphs of FF.Comment: 23 pages. arXiv admin note: text overlap with arXiv:2306.1674

    Spectral extremal graphs for edge blow-up of star forests

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    The edge blow-up of a graph GG, denoted by Gp+1G^{p+1}, is obtained by replacing each edge of GG with a clique of order p+1p+1, where the new vertices of the cliques are all distinct. Yuan [J. Comb. Theory, Ser. B, 152 (2022) 379-398] determined the range of the Tur\'{a}n numbers for edge blow-up of all bipartite graphs and the exact Tur\'{a}n numbers for edge blow-up of all non-bipartite graphs. In this paper we prove that the graphs with the maximum spectral radius in an nn-vertex graph without any copy of edge blow-up of star forests are the extremal graphs for edge blow-up of star forests when nn is sufficiently large.Comment: 22. arXiv admin note: text overlap with arXiv:2208.0655

    Rapid assessment of sustainability in Mainland China

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    This paper presents an approach for rapid assessment of sustainability for Mainland China based on a multilayer index system. Efficient assessment is conducted with the basic mapping units at county and city levels. After evaluating a comprehensive sustainable development index, SDI, for each unit, five rankings of sustainability are determined, and a zonation map produced. Regional characteristics and differences are interpreted through macro-analysis of the spatial variation in SDI. A sensitivity analysis is performed by which the weights of the sub-indices are altered by +/- 20%, and SDI re-evaluated; the resulting grades remain the same, thus confirming the robustness of the technique. Moreover, the accuracy of the proposed approach is indirectly validated by comparison with assessment results from an alternative systems analysis method. It is found that major conurbations such as Beijing have relatively high levels of sustainability, whereas provinces in central and western China require investment to improve their sustainability. (C) 2009 Elsevier Ltd. All rights reserved

    Consecutive Slides on Axial View Is More Effective Than Transversal Diameter to Differentiate Mechanisms of Single Subcortical Infarctions in the Lenticulostriate Artery Territory

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    Objective: Lipohyalinosis or atherosclerosis might be responsible for single subcortical infarctions (SSIs); however, ways of differentiating between the two clinically remain uncertain. We aimed to investigate whether consecutive slides on axial view or transversal diameter is more effective to differentiate mechanisms by comparing their relationships with white matter hyperintensities (WMHs).Methods: All the participants from the Standard Medical Management in Secondary Prevention of Ischemic stroke in China (SMART) cohort who had SSIs in the lenticulostriate artery territory were included and categorized according to consecutive slides on axial view (≄4 consecutive slices or not) and transversal diameter (≄15 mm or not). The associations between the severity of WMHs and the different categories were analyzed.Results: Among the 3,821 patients of the SMART study, 281 had diffusion-weighted image-proven SSIs in the lenticulostriate artery territory. When classified by consecutive slides on axial view, SSIs on ≄4 slices were significantly associated with the severity of the WMHs, both in deep WMH (DWMH) (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.11–0.97; p = 0.04) and periventricular hyperintensity (PVH) (OR, 0.37; 95% CI, 0.17–0.78; p = 0.01). No such association was found on the basis of the transversal diameter (p > 0.1).Conclusion: Consecutive slides on axial view (≄4 consecutive slices) might be more effective than transversal diameter to identify the atherosclerotic mechanisms of SSIs in the lenticulostriate artery territory.Clinical Trial Registration:http://www.clinicaltrials.gov. Unique identifier: NCT0066484

    Assessment of flooding impacts in terms of sustainability in mainland China

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    An understanding of flood impact in terms of sustainability is vital for long-term disaster risk reduction. This paper utilizes two important concepts: conventional insurance related flood risk for short-term damage by specific flood events, and long-term flood impact on sustainability. The Insurance Related Flood Risk index, IRFR, is defined as the product of the Flood Hazard Index (FHI) and Vulnerability. The Long-term Flood Impact on Sustainability index. LFIS, is the ratio of the flood hazard index to the Sustainable Development Index (SDI). Using a rapid assessment approach, quantitative assessments of IRFR and LFIS are carried out for 2339 counties and cities in mainland China. Each index is graded from 'very low' to 'very high' according to the eigenvalue magnitude of cluster centroids. By combining grades of FHI and SDI, mainland China is then classified into four zones in order to identify regional variations in the potential linkage between flood hazard and sustainability. Zone I regions, where FHI is graded 'very low' or low' and SDI is 'medium' to 'very high', are mainly located in western China. Zone II regions, where FHI and SDI are 'medium' or 'high', occur in the rapidly developing areas of central and eastern China. Zone III regions, where FHI and SDI are 'very low' or 'low', correspond to the resource-based areas of western and north-central China. Zone IV regions, where FHI is 'medium' to 'very high' and SDI is 'very low' to 'low', occur in ecologically fragile areas of south-western China. The paper also examines the distributions of IRFR and LFIS throughout mainland China. Although 57% of the counties and cities have low IRFR values, 64% have high LFIS values. The modal values of LFIS are ordered as Zone I < Zone II approximate to Zone III < Zone IV; whereas the modal values of IRFR are ordered as Zone I < Zone III < Zone IV < Zone II. It is recommended that present flood risk policies be altered towards a more sustainable flood risk management strategy in areas where LFIS and IRFR vary significantly, with particular attention focused on Zone IV regions, which presently experience poverty and a deteriorating eco-system. (C) 2010 Elsevier Ltd. All rights reserved

    Risk factors and prediction model of sleep disturbance in patients with maintenance hemodialysis: A single center study

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    ObjectivesThis study aimed to explore the risk factors and develop a prediction model of sleep disturbance in maintenance hemodialysis (MHD) patients.MethodsIn this study, 193 MHD patients were enrolled and sleep quality was assessed by Pittsburgh Sleep Quality Index. Binary logistic regression analysis was used to explore the risk factors for sleep disturbance in MHD patients, including demographic, clinical and laboratory parameters, and that a prediction model was developed on the basis of risk factors by two-way stepwise regression. The final prediction model is displayed by nomogram and verified internally by bootstrap resampling procedure.ResultsThe prevalence of sleep disturbance and severe sleep disturbance in MHD patients was 63.73 and 26.42%, respectively. Independent risk factors for sleep disturbance in MHD patients included higher 0.1*age (OR = 1.476, 95% CI: 1.103–1.975, P = 0.009), lower albumin (OR = 0.863, 95% CI: 0.771–0.965, P = 0.010), and lower 10*calcium levels (OR = 0.747, 95% CI: 0.615–0.907, P = 0.003). In addition, higher 0.1*age, lower albumin levels, and anxiety were independently associated with severe sleep disturbance in MHD patients. A risk prediction model of sleep disturbance in MHD patients showed that the concordance index after calibration is 0.736, and the calibration curve is approximately distributed along the reference line.ConclusionsOlder age, lower albumin and calcium levels are higher risk factors of sleep disturbance in MHD, and the prediction model for the assessment of sleep disturbance in MHD patients has excellent discrimination and calibration

    Facile Synthesis of High Quality Graphene Nanoribbons

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    Graphene nanoribbons have attracted attention for their novel electronic and spin transport properties1-6, and because nanoribbons less than 10 nm wide have a band gap that can be used to make field effect transistors. However, producing nanoribbons of very high quality, or in high volumes, remains a challenge. Here, we show that pristine few-layer nanoribbons can be produced by unzipping mildly gas-phase oxidized multiwalled carbon nanotube using mechanical sonication in an organic solvent. The nanoribbons exhibit very high quality, with smooth edges (as seen by high-resolution transmission electron microscopy), low ratios of disorder to graphitic Raman bands, and the highest electrical conductance and mobility reported to date (up to 5e2/h and 1500 cm2/Vs for ribbons 10-20 nm in width). Further, at low temperature, the nanoribbons exhibit phase coherent transport and Fabry-Perot interference, suggesting minimal defects and edge roughness. The yield of nanoribbons was ~2% of the starting raw nanotube soot material, which was significantly higher than previous methods capable of producing high quality narrow nanoribbons1. The relatively high yield synthesis of pristine graphene nanoribbons will make these materials easily accessible for a wide range of fundamental and practical applications.Comment: Nature Nanotechnology in pres

    The morphometry of soft tissue insertions on the tibial plateau: Data acquisition and statistical shape analysis

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    This study characterized the soft tissue insertion morphometrics on the tibial plateau and their inter-relationships as well as variabilities. The outlines of the cruciate ligament and meniscal root insertions along with the medial and lateral cartilage on 20 cadaveric tibias (10 left and 10 right knees) were digitized and co-registered with corresponding CT-based 3D bone models. Generalized Procrustes Analysis was employed in conjunction with Principal Components Analysis to first create a geometric consensus based on tibial cartilage and then determine the means and variations of insertion morphometrics including shape, size, location, and inter-relationship measures. Step-wise regression analysis was conducted in search of parsimonious models relating the morphometric measures to the tibial plateau width and depth, and basic anthropometric and gender factors. The analyses resulted in statistical morphometric representations for Procrustes-superimposed cruciate ligament and meniscus insertions, and identified only a few moderate correlations (R 2: 0.37-0.49). The study provided evidence challenging the isometric scaling based on a single dimension frequently employed in related morphometric studies, and data for evaluating cruciate ligament reconstruction strategies in terms of re-creating the native anatomy and minimizing the risk of iatrogenic injury. It paved the way for future development of computer-aided personalized orthopaedic surgery applications improving the quality of care and patient safety, and biomechanical models with a better population or average representation

    2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales.

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    Correction to: 2021 Taxonomic update of phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales. Archives of Virology (2021) 166:3567–3579. https://doi.org/10.1007/s00705-021-05266-wIn March 2021, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by four families (Aliusviridae, Crepuscuviridae, Myriaviridae, and Natareviridae), three subfamilies (Alpharhabdovirinae, Betarhabdovirinae, and Gammarhabdovirinae), 42 genera, and 200 species. Thirty-nine species were renamed and/or moved and seven species were abolished. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.This work was supported in part through Laulima Government Solutions, LLC prime contract with the US National Institute of Allergy and Infectious Diseases (NIAID) under Contract No. HHSN272201800013C. J.H.K. performed this work as an employee of Tunnell Government Services (TGS), a subcontractor of Laulima Government Solutions, LLC under Contract No. HHSN272201800013C. This work was also supported in part with federal funds from the National Cancer Institute (NCI), National Institutes of Health (NIH), under Contract No. 75N91019D00024, Task Order No. 75N91019F00130 to I.C., who was supported by the Clinical Monitoring Research Program Directorate, Frederick National Lab for Cancer Research. This work was also funded in part by Contract No. HSHQDC-15-C-00064 awarded by DHS S&T for the management and operation of The National Biodefense Analysis and Countermeasures Center, a federally funded research and development center operated by the Battelle National Biodefense Institute (V.W.); and NIH contract HHSN272201000040I/HHSN27200004/D04 and grant R24AI120942 (N.V., R.B.T.). S.S. acknowledges partial support from the Special Research Initiative of Mississippi Agricultural and Forestry Experiment Station (MAFES), Mississippi State University, and the National Institute of Food and Agriculture, US Department of Agriculture, Hatch Project 1021494. Part of this work was supported by the Francis Crick Institute which receives its core funding from Cancer Research UK (FC001030), the UK Medical Research Council (FC001030), and the Wellcome Trust (FC001030).S
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