Spatial-temporal

时空
  • 文章类型: Journal Article
    自动估价模型(AVM)被金融机构广泛用于估计住宅抵押贷款的财产价值。从AVM获得的定价误差分布通常显示为肥尾(Pender2016;Demiroglu和JamesManagementScience,64(4),1747-17602018)。尾部的极端事件通常被称为“黑天鹅”(Taleb2010)在金融和他们的存在复杂的金融风险管理,评估,和监管。我们通过理论证明,蒙特卡罗实验,以及一个经验例子,即定价误差的非正态与房屋定价模型的拟合优度之间存在直接关系。具体来说,我们提供了一个使用美国住房价格的实证例子,其中我们证明了学生t分布的估计自由度与具有空间和时空依赖性的复杂评估模型的拟合优度之间几乎完美的线性关系。
    Automated valuation models (AVMs) are widely used by financial institutions to estimate the property value for a residential mortgage. The distribution of pricing errors obtained from AVMs generally show fat tails (Pender 2016; Demiroglu and James Management Science, 64(4), 1747-1760 2018). The extreme events on the tails are usually known as \"black swans\" (Taleb 2010) in finance and their existence complicates financial risk management, assessment, and regulation. We show via theory, Monte Carlo experiments, and an empirical example that a direct relation exists between non-normality of the pricing errors and goodness-of-fit of the house pricing models. Specifically, we provide an empirical example using US housing prices where we demonstrate an almost perfect linear relation between the estimated degrees-of-freedom for a Student\'s t distribution and the goodness-of-fit of sophisticated evaluation models with spatial and spatialtemporal dependence.
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  • 文章类型: Journal Article
    COVID-19大流行是一种新现象,已经在许多方面影响了人们的生活方式,例如恐慌性购买(所谓的“仓鼠购物”),采用家庭办公室,和零售购物的下降。对于运输规划师和运营商,在COVID-19封锁期间,即封锁前,分析POI(兴趣点)在需求模式中的空间因素作用是很有趣的。
    这项研究说明了POI访问率或受欢迎程度数据以及其他公开可用数据的用例,用于分析像COVID-19这样的高度动态和破坏性事件期间的需求模式和空间因素。我们通过使用锁定(治疗)作为虚拟变量,开发回归模型来分析空间和非空间属性与慕尼黑COVID-19锁定之前和期间POI流行程度的相关性,具有主要和相互作用的影响。
    在我们针对慕尼黑的案例研究中,在解释受欢迎程度时,我们发现停止距离和星期几等特征的一致行为。仅在非线性模型中发现停车区域是相关的。锁定与POI类型的相互作用,停止距离,一周中的一天被发现非常重要。由于存在不同的城市特定因素,结果可能无法转移到其他城市。
    我们案例研究的结果提供了限制对POI的影响的证据,并显示了POI类型和停止距离与POI流行度的显着相关性。这些结果表明,由于限制,影响的局部和时间变化,这可能会影响城市如何在未来的破坏性事件中适应不同的需求和由此产生的交通模式。
    UNASSIGNED: The COVID-19 pandemic is a new phenomenon and has affected the population\'s lifestyle in many ways, such as panic buying (the so-called \"hamster shopping\"), adoption of home-office, and decline in retail shopping. For transportation planners and operators, it is interesting to analyze the spatial factors\' role in the demand patterns at a POI (Point of Interest) during the COVID-19 lockdown viz-a-viz before lockdown.
    UNASSIGNED: This study illustrates a use-case of the POI visitation rate or popularity data and other publicly available data to analyze demand patterns and spatial factors during a highly dynamic and disruptive event like COVID-19. We develop regression models to analyze the correlation of the spatial and non-spatial attributes with the POI popularity before and during COVID-19 lockdown in Munich by using lockdown (treatment) as a dummy variable, with main and interaction effects.
    UNASSIGNED: In our case-study for Munich, we find consistent behavior of features like stop distance and day-of-the-week in explaining the popularity. The parking area is found to be correlated only in the non-linear models. Interactions of lockdown with POI type, stop-distance, and day-of-the-week are found to be strongly significant. The results might not be transferable to other cities due to the presence of different city-specific factors.
    UNASSIGNED: The findings from our case-study provide evidence of the impact of the restrictions on POIs and show the significant correlation of POI-type and stop distance with POI popularity. These results suggest local and temporal variability in the impact due to the restrictions, which can impact how cities adapt their transport services to the distinct demand and resulting mobility patterns during future disruptive events.
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  • 文章类型: Journal Article
    我们研究视频绘画,其目的是从损坏的帧恢复逼真的纹理。通过将其他帧作为参考,从而可以将相关纹理转移到损坏的帧,从而取得了最新进展。然而,现有的视频修复方法忽略了模型提取信息和重建内容的能力,导致无法重建应准确转移的纹理。在本文中,我们提出了一种新颖有效的时空纹理变换网络(STTTN)用于视频修补。STTTN由六个紧密相关的模块组成,这些模块针对视频修补任务进行了优化:特征相似性度量,以实现更准确的帧预修复,具有强大信息提取能力的编码器,用于查找相关性的嵌入模块,粗低频特征传递,精化高频特征传递,和解码器具有准确的内容重建能力。这样的设计鼓励跨输入和参考帧的联合特征学习。为了证明该模型的先进性和有效性,我们通过使用标准的固定掩模和更真实的移动对象掩模,对多个数据集进行全面的消融学习和定性和定量实验。良好的实验结果证明了STTTN的真实性和可靠性。
    We study video inpainting, which aims to recover realistic textures from damaged frames. Recent progress has been made by taking other frames as references so that relevant textures can be transferred to damaged frames. However, existing video inpainting approaches neglect the ability of the model to extract information and reconstruct the content, resulting in the inability to reconstruct the textures that should be transferred accurately. In this paper, we propose a novel and effective spatial-temporal texture transformer network (STTTN) for video inpainting. STTTN consists of six closely related modules optimized for video inpainting tasks: feature similarity measure for more accurate frame pre-repair, an encoder with strong information extraction ability, embedding module for finding a correlation, coarse low-frequency feature transfer, refinement high-frequency feature transfer, and decoder with accurate content reconstruction ability. Such a design encourages joint feature learning across the input and reference frames. To demonstrate the advancedness and effectiveness of the proposed model, we conduct comprehensive ablation learning and qualitative and quantitative experiments on multiple datasets by using standard stationary masks and more realistic moving object masks. The excellent experimental results demonstrate the authenticity and reliability of the STTTN.
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  • 文章类型: Journal Article
    COVID-19大流行对人类健康和社会经济产生了重大影响。一些研究检查了与COVID-19相关的健康风险因素的时空格局,但尚未充分考虑人口流动溢出效应。在本文中,开发了基于人口流的时空特征向量滤波模型(FLOW-ESTF),以同时考虑时空模式和人口流连通性。提出的FLOW-ESTF方法有效地提高了模型预测精度,这可以帮助政府了解感染风险水平并制定适当的控制政策。选定的人口流动时空特征向量对建模贡献最大,相应特征向量集的可视化有助于探索潜在的时空模式和大流行传播节点。模型系数可以反映健康风险因素如何有助于建立州级COVID-19每周增加病例的模型,以及它们的影响如何随时间变化,这可以帮助人们和政府更好地意识到潜在的健康风险,并在不同阶段调整控制措施。提取的人口流动时空特征向量不仅代表了人口流动的影响及其溢出效应,而且还代表了一些可能被忽略的健康风险因素。这可以为解决COVID-19建模中的空间和时间自相关问题提供有效的途径,并且可以直观地发现潜在的空间模式,这将部分弥补潜在风险变量考虑不足和数据缺失的问题。
    The COVID-19 pandemic has had great impact on human health and social economy. Several studies examined spatial and temporal patterns of health risk factors associated with COVID-19, but population flow spillover effect has not been sufficiently considered. In this paper, a population flow-based spatial-temporal eigenvector filtering model (FLOW-ESTF) was developed to consider spatial-temporal patterns and population flow connectivity simultaneously. The proposed FLOW-ESTF method efficiently improved model prediction accuracy, which could help the government aware of the infection risk level and to make suitable control policies. The selected population flow spatial-temporal eigenvector contributed most to modeling and the visualization of corresponding eigenvector set helped to explore the underlying spatial-temporal patterns and pandemic transmission nodes. The model coefficients could reflect how health risk factors contribute the modeling of state-level COVID-19 weekly increased cases and how their influence changed through time, which could help people and government to better aware the potential health risks and to adjust control measures at different stage. The extracted population flow spatial-temporal eigenvector not only represents influence of population flow and its spillover effects but also represents some possible omitted health risk factors. This could provide an efficient path to solve the problem of spatial and temporal autocorrelation in COVID-19 modeling and an intuitive way to discover underlying spatial patterns, which will partially compensate for the problems of insufficient consideration of potential risk variables and missing data.
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  • 文章类型: Journal Article
    目的:这是一项长期的回顾性研究,为了解武威市1995-2016年肝硬化的时空变化趋势,找出高发地区。为制定武威市肝硬化综合防治策略提供理论依据。方法:这里,我们提取了在武威市12家哨点医院接受治疗的肝硬化患者的病历数据。我们使用SAS和Joinpoint回归程序进行数据分析,SaTScan9.4软件,用于聚类区域检测,和ArcGIS10.2软件进行地理分布制图。结果:3308例肝硬化患者(平均年龄,55.34年)纳入本研究,15.9%的人年龄在50-54岁之间。大多数是男性(2716,65.8%),性别比为1.92:1,按职业划分的农民(1369,60.3%)。基本社会医疗保险制度覆盖了1271名患者(63%)的医疗费用。1995-2016年进行的Joinpoint回归分析显示,在2010年,2013年和2016年,标准化肝硬化率[平均年度变化百分比(AAPC)=16.7%(95%CI,10.2-23.5%)]增加了三个连接点。1995年至2010年的年度百分比变化(APC)为11.13%(95%CI:6.5-16.0),2010年至2013年的APC为66.48%(95%CI:16.0-138.9);相反,从2013年到2016年,APC为4.4%(95%CI,-7.5-17.8%).洪沙岗镇平均发病率最高。2010年以后,各乡镇的发病率逐渐上升。结果显示,在每个乡镇,肝硬化发病率有一定的空间聚集性,且是非随机的.武威市75个乡镇有4个肝硬化集群。数据收集自2011年至2016年。结论:1995-2016年武威市肝硬化发病率仍呈逐年上升趋势,但自2013年以来增速放缓。在武威,女性患者的肝硬化标准化率稳步上升,并且比男性患者快。有必要加强诊断,治疗,预防,肝硬化相关疾病的防治措施。空间扫描的结果,基本空间分布,聚合时间,和时间趋势分析是一致的。
    Objectives: This was a long-term retrospective study, aiming to understand the temporal and spatial trend of cirrhosis in Wuwei from 1995 to 2016, explore its spatio-temporal aggregation, and find out the high incidence areas. To provide theoretical basis for the formulation of comprehensive prevention and treatment strategy of cirrhosis in Wuwei. Methods: Herein, we extracted data of cirrhosis patients who were treated in 12 sentinel hospitals in Wuwei from their medical records. We used SAS and Joinpoint Regression Program for data analysis, SaTScan 9.4 software for clustering area detection, and ArcGIS 10.2 software for geographical distribution mapping. Results: Among 3308 patients with liver cirrhosis (average age, 55.34 years) included in this study, 15.9% were aged 50-54 years. The majority were men (2716, 65.8%), with a sex ratio of 1.92:1 and peasants by occupation (1369, 60.3%). The basic social medical insurance system covered the healthcare costs of 1271 patients (63%). A Joinpoint regression analysis done for 1995-2016 revealed an increase in the standardized cirrhosis rate [average annual percent change (AAPC) = 16.7% (95% CI, 10.2-23.5%)] with three joinpoints in 2010, 2013, and 2016. The annual percent change (APC) from 1995 to 2010 was 11.13% (95% CI: 6.5-16.0), and APC from 2010 to 2013 was 66.48% (95% CI:16.0-138.9); conversely, from 2013 to 2016, APC was 4.4% (95% CI, -7.5-17.8%). Hongshagang Town showed the highest average incidence. Each township showed a gradual increase in the incidence after 2010. The results revealed that in each township, liver cirrhosis incidence had some spatial aggregation and was nonrandom. Four liver cirrhosis clusters were noted in 75 townships in Wuwei. Data were gathered from 2011 to 2016. Conclusions: From 1995 to 2016, the incidence of cirrhosis in Wuwei still showed an increasing trend, but the growth rate slowed down since 2013. In Wuwei, the rate of standardization of cirrhosis in female patients increased steadily and faster than in male patients. It is necessary to strengthen the diagnosis, treatment, prevention, and control measures of cirrhosis-related diseases. The results of spatial scanning, basic spatial distribution, aggregation time, and time trend analysis were consistent.
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  • 文章类型: Journal Article
    Artificial intelligence (AI) has served humanity in many applications since its inception. Currently, it dominates the imaging field-in particular, image classification. The task of image classification became much easier with machine learning (ML) and subsequently got automated and more accurate by using deep learning (DL). By default, DL consists of a single architecture and is termed solo deep learning (SDL). When two or more DL architectures are fused, the result is termed a hybrid deep learning (HDL) model. The use of HDL models is becoming popular in several applications, but no review of these uses has been designed thus far. Therefore, this study provides the first narrative HDL review by considering all facets of image classification using AI.
    Our review employs a PRISMA search strategy using Google Scholar, PubMed, IEEE, and Elsevier Science Direct, through which 127 relevant HDL studies were considered. Based on the computer vision evolution, HDLs were subsequently classified into three categories (spatial, temporal, and spatial-temporal). Each study was then analyzed based on several attributes, including continent, publisher, hybridization of two DL or ML, architecture layout, application type, data set type, dataset size, feature extraction methodology, connecting classifier, performance evaluation metrics, and risk-of-bias.
    The HDL models have shown stable and superior performance by taking the best aspects of two or more solo DL or fusion of DL with ML models. Our findings indicate that HDL is being applied aggressively to several medical and non-medical applications. Furthermore, risk-of-bias is highly debatable for DL and HDL models.
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  • 文章类型: Journal Article
    基于骨架的人体动作识别已经取得了很大的进展,特别是随着图卷积网络(GCN)的发展。最重要的工作是ST-GCN,从骨架序列中自动学习空间和时间模式。然而,这种方法仍然存在一些缺陷:只有短程相关性得到重视,由于图卷积的接受场有限。然而,长期依赖对于识别人类行为至关重要。在这项工作中,我们建议使用时空相对变换器(ST-RT)来克服这些缺陷。通过引入中继节点,ST-RT避免了变压器架构,打破了空间上固有的骨架拓扑和时间维度上骨架序列的顺序。此外,我们挖掘运动中包含的不同尺度的动态信息。最后,四个ST-RT,从四种骨架序列中提取时空特征,融合形成最终模型,多流时空相对变换器(MSST-RT),以提高性能。广泛的实验在基于骨架的动作识别的三个基准上评估了所提出的方法:NTURGBD,NTURGB+D120和UAV-Human。结果表明,MSST-RT在性能方面与SOTA相当。
    Skeleton-based human action recognition has made great progress, especially with the development of a graph convolution network (GCN). The most important work is ST-GCN, which automatically learns both spatial and temporal patterns from skeleton sequences. However, this method still has some imperfections: only short-range correlations are appreciated, due to the limited receptive field of graph convolution. However, long-range dependence is essential for recognizing human action. In this work, we propose the use of a spatial-temporal relative transformer (ST-RT) to overcome these defects. Through introducing relay nodes, ST-RT avoids the transformer architecture, breaking the inherent skeleton topology in spatial and the order of skeleton sequence in temporal dimensions. Furthermore, we mine the dynamic information contained in motion at different scales. Finally, four ST-RTs, which extract spatial-temporal features from four kinds of skeleton sequence, are fused to form the final model, multi-stream spatial-temporal relative transformer (MSST-RT), to enhance performance. Extensive experiments evaluate the proposed methods on three benchmarks for skeleton-based action recognition: NTU RGB+D, NTU RGB+D 120 and UAV-Human. The results demonstrate that MSST-RT is on par with SOTA in terms of performance.
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  • 文章类型: Journal Article
    Physical activity (PA), associated with all-cause mortality, morbidity, and healthcare costs, improves vitamin D absorption, immune response, and stress when completed outdoors. Rural communities, which experience PA inequities, rely on trails to meet PA guidelines. However, current trail audit methods could be more efficient and accurate, which geospatial video may support. Therefore, the study purpose was (1) to identify and adopt validated instruments for trail audit evaluations using geospatial video and a composite score and (2) to determine if geospatial video and a composite score motivate (influence the decision to use) specific trail selection among current trail users. Phase 1 used a mixed-method exploratory sequential core design using qualitative data, then quantitative data for the development of the Spatial-temporal Trail Audit Tool (STAT). Geospatial videos of two Northeast Ohio trails were collected using a bicycle-mounted spatial video camera and video analysis software. The creation of STAT was integrated from Neighborhood Environment Walkability Scale (NEWS), Walk Score, and Path Environment Audit Tool (PEAT) audit tools based on four constructs: trail accessibility, conditions, amenities, and safety. Scoring was determined by three independent reviewers. Phase 2 included a mixed-method convergent core design to test the applicability of STAT for trail participant motivation. STAT has 20 items in 4 content areas computing a composite score and was found to increase trail quality and motivation for use. STAT can evaluate trails for PA using geospatial video and a composite score which may spur PA through increased motivation to select and use trails.
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  • 文章类型: Journal Article
    人类偏肺病毒(HMPV)和呼吸道合胞病毒(RSV)是儿童病毒性严重急性呼吸道疾病的主要原因。这两种病毒都属于Pneumoviridae家族,并显示重叠的临床,流行病学和传播特征。然而,目前尚不清楚这两种病毒是否具有相似的地理传播模式,这可能有助于设计和评估其流行病控制措施。
    我们使用从5个国家获得的232个HMPV和842个RSV附着(G)糖蛋白基因序列,进行了比较系统发育和系统地理学分析,以探索非洲HMPV和RSV的时空格局(冈比亚,赞比亚,马里,南非,和肯尼亚),2011年8月至2014年1月。
    系统地理分析经常发现RSV和HMPV的传播模式相似。病毒序列通常按区域聚集,即,西非(马里,Gambia),东非(肯尼亚)和南部非洲(赞比亚,南非),在邻国之间观察到相似的基因型优势模式。HMPV和RSV国家流行均以多种基因型的共同循环为特征。来自不同非洲次区域的序列(东部,西非和南部非洲)分为不同的集群,散布着来自全球其他国家的序列。
    在我们的分析中观察到的病毒序列的空间聚类模式和基因型优势模式表明了强烈的区域联系和主要的局部传播。地理集群进一步表明,从全球范围内独立引入非洲的HMPV和RSV变体,和地方区域多样化。
    Human metapneumovirus (HMPV) and respiratory syncytial virus (RSV) are leading causes of viral severe acute respiratory illnesses in childhood. Both the two viruses belong to the Pneumoviridae family and show overlapping clinical, epidemiological and transmission features. However, it is unknown whether these two viruses have similar geographic spread patterns which may inform designing and evaluating their epidemic control measures.
    We conducted comparative phylogenetic and phylogeographic analyses to explore the spatial-temporal patterns of HMPV and RSV across Africa using 232 HMPV and 842 RSV attachment (G) glycoprotein gene sequences obtained from 5 countries (The Gambia, Zambia, Mali, South Africa, and Kenya) between August 2011 and January 2014.
    Phylogeographic analyses found frequently similar patterns of spread of RSV and HMPV. Viral sequences commonly clustered by region, i.e., West Africa (Mali, Gambia), East Africa (Kenya) and Southern Africa (Zambia, South Africa), and similar genotype dominance patterns were observed between neighbouring countries. Both HMPV and RSV country epidemics were characterized by co-circulation of multiple genotypes. Sequences from different African sub-regions (East, West and Southern Africa) fell into separate clusters interspersed with sequences from other countries globally.
    The spatial clustering patterns of viral sequences and genotype dominance patterns observed in our analysis suggests strong regional links and predominant local transmission. The geographical clustering further suggests independent introduction of HMPV and RSV variants in Africa from the global pool, and local regional diversification.
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  • 文章类型: Journal Article
    Geographic and temporal variation in positive surgical margins (PSM) for prostate cancer after radical prostatectomy (RP) has been observed. However, it is unclear how much of this variation could be attributed to patient, surgeon, institution, or socioeconomic-related factors and the impact of PSM on death among localized prostate cancer patients.
    This study aimed to assess the independent and relative contribution of the patient, surgeon, institution and area-level risk factors on geographic and temporal variation of PSM and evaluate the impact of PSM on five-year all-cause and prostate cancer-specific mortality among localized prostate cancer patients. Within the hierarchical-related regression approach, we utilised Bayesian spatial-temporal multi-level models to study individual and area-level predictors with the outcomes, while accounting for geographically structured and unstructured correlation and non-linear trends.
    Individual-level data included 10,075 localized prostate cancer cases with RP reported to the Prostate Cancer Outcomes Registry Victoria between 2009 and 2018. Area-level data comprised socio-economic disadvantage and remoteness data at the local government area level in Victoria, Australia. 26 % of patients had PSM, and the rates varied across areas by years. This variation was mainly associated with NCCN risk, followed by RP techniques, surgical institution type, surgeon volume and socio-economic disadvantage. Intermediate (Odds ratio/OR = 1.21,95 % credible interval/Crl = 1.05-1.41), high/very-high risk groups (OR = 2.24,95 % Crl = 1.91-2.64) and public surgical institution (OR = 1.64, 95 % Crl = 1.46-1.84) were independently associated with a higher likelihood of PSM. Robot-assisted (OR = 0.61, 95 % Crl = 0.55-0.68), laparoscopic RP (OR = 0.76, 95 % Crl = 0.62-0.93), high-volume surgeon (OR = 0.84, 95 % Crl = 0.76-0.93) and socio-economically least disadvantaged status (OR = 0.78, 95 % Crl = 0.64-0.94) showed a lower likelihood of PSM. PSM was also independently associated with a higher five-year all-cause and prostate cancer-specific mortality.
    Aggressive tumour characteristics and RP techniques were the main contributors to the likelihood of PSM following RP. Reducing the prevalence of PSM will generally improve prostate cancer-specific and all-cause mortality.
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