Clusters of Nonmedical Exemptions to Vaccination in Illinois K–12 Schools

Vaccination rates in Illinois schools are decreasing as more parents opt for nonmedical exemptions (NMEs). At the local scale, higher levels of exemptions affect herd immunity levels. Few studies have previously conducted or proposed methods to conduct local-scale spatial and temporal cluster pattern analysis. This study used vaccination exemption data from the Illinois School Board of Education’s annual Immunization School Survey for the 2003–2004 and 2013–2014 academic years. The Getis–Ord General G statistic was used to identify cluster detection by individual vaccine at the school level. The Getis–Ord Gi* statistic was used with two different parameter models to identify hot and cold spots. This study found that NMEs are highly clustered. More clusters of high and low NMEs were identified for the 2013–2014 academic year than for 2003–2004. The percentages of schools that were neither hot nor cold averaged 94.0 percent for the 2003–2004 school year and 78.7 percent for the 2013–2014 school year. NME rates in Illinois are rising. The increase in hot and cold spots is evidence that the polarity of vaccination choice is growing. As vaccination exemption rates continue to polarize U.S. society, it is essential for public health efforts to monitor and conduct local-level studies. Key Words: antivaccination, hot spot analysis, medical geography, nonmedical exemption, spatial statistics.     

Trends in Interdiurnal Temperature Variation for the Central United States, 1945–1985

Temporal variation in the absolute value of interdiurnal variability (AIDV) of January maximum temperatures is examined for the period 1945–1985 in the central United States (90°–105°W). AIDV indicates the magnitude of day-to-day changes in the maximum temperature. Five-year running-mean AIDV values decreased significantly throughout the period. This trend was apparent for the region overall and for the 10 of the 20 study sites analyzed individually. Temporal variation in AIDV values was significantly related to mid-tropospheric flow patterns over the central United States. Meridional circulation was associated with smaller AIDV values in all sites except those in the northwestern and southeastern corners of the study area, whereas zonal flow was linked to larger interdiurnal temperature change. The analysis of selected individual years indicated that mid-tropospheric circulation patterns were more persistent with meridional flow, and surface cyclones and their associated surface fronts tracked through the study area less frequently than in years with zonal flow. Analysis at a daily temporal resolution revealed an added dimension of trends in temperature variability beyond those apparent with a coarser monthly resolution. These results emphasize the importance of finer temporal resolution in the analysis of both past and projected climate change; regionally summarized monthly temperature values mask important variation in temperature trends apparent at shorter temporal and more local spatial scales.     

A Typology of U.S. Shrinking Cities

The literature on shrinking cities has significantly grown in recent years. Little work, however, has been done toward the development of a shrinking city typology, which could help inform solutions and strategies to address problems associated with population loss. With a focus on central cities, this article identifies 367 shrinking cities within the United States and categorizes them using a geographic information system to identify seven types of shrinking cities in the United States: (1) large shrinking central cities, (2) inner-ring suburbs of shrinking central cities, (3) outer-ring suburbs of shrinking central cities, (4) inner-ring suburbs of growing central cities, (5) outer-ring suburbs of growing central cities, (6) small shrinking central cities in small Metropolitan Statistical Areas, and (7) small shrinking cities in small Micropolitan Statistical Areas. The empirically generated clusters, combined with associated social and demographic information, identify separate but sometimes interrelated shrinking city types and provide a new perspective for addressing the problems faced by U.S. shrinking cities. Key Words: population decline, shrinking cities, typology, urban population.     

Geography and Planning: Some Perspectives

This paper analyzes the migration of Puerto Rican-born women from the United States to Puerto Rico using longitudinal data. We hypothesize that sojourn length in the United States is a function of both structural (macro-level economic and cultural factors) and behavioral (micro-level life-cycle experiences and personal attributes) variables. We test these hypotheses by estimating a proportional hazards model. The parameter estimates of this model indicate that sojourn length in the United States, and thus the decision to return to Puerto Rico, is a function of wage trends and community characteristics on the mainland plus a number of individual attributes that include education, marriage, and childbirth.     

Preliminary Analysis of the Temporal Patterns of Heavy Rainfall across the Southeastern United States

This paper examines trends in heavy rainfall events across the southeastern United States over the past century. Time series of the number of annual storm events over a 76.2 mm threshold were used for analysis. Significant trends that had some spatial coherence were identified. Increasing trends were detected in a region extending from northeastern Texas to the Appalachians, with a weaker signal of decreasing events along the East Coast. These patterns may be linked to fluctuations in the strength and migration of the Bermuda High.     

Modeling River Connectivity Using the Barrier Assessment Tool and Available Data on Registered Dams in the Guadalupe–San Antonio River System,Texas

The rate of dam building has declined in the United States, but dam building is still considered an integral part of water supply management, particularly in arid and semiarid regions. Understanding how dams affect river connectivity is a key component of river basin management. This study analyzed the spatial and temporal patterns of fragmentation in the Guadalupe–San Antonio River System (GSARS) and how these patterns were related to dam size, age, and purpose. Using a shapefile of registered dams and the National Hydrography Dataset High Resolution (NHD-HR) as input data for the Barrier Assessment Tool (BAT), six successive connectivity models were created. The average length of functional river networks (FRNs) decreased over time but the number of FRNs over 100?km stayed relatively stable. Fragmentation in the GSARS was concentrated around urban centers, and the majority of fragmentation occurred gradually as dams separated small FRNs along tributaries and headwaters. This gradual decline in longitudinal connectivity was punctuated by sporadically large separations of river networks by particular dams based on their location and time of commissioning. The methodology presented here provides a way to analyze both the extent and the temporal evolution of fragmentation in a river system. Key Words: Barrier Assessment Tool (BAT), fragmentation, functional river networks, river connectivity.     

INCIDENTS OF TERRORISM IN THE UNITED STATES, 1997–2005

ABSTRACT. The geography of terrorism remains underexplored. By focusing on the spatial patterns of terrorist attacks, the settings and land uses in which attacks occur, and the methods used to perpetrate violence, this analysis helps build a theory of terrorism geography. Between 1 January 1997 and 11 September 2005, 178 terrorist incidents occurred in the United States. Analysis of these incidents suggests three insights. At the national scale, terrorism in the United States clustered in large urban areas, with regional differentiation of terrorist motives and targets. At the scale of individual attack sites, terrorist motivations pinpointed offices, clinics, and public spaces; right‐wing violence, military, government, and infrastructural targets; and religious terrorism, commercial and special land uses. At the scale of individual interactions, terrorists crossed paths with victims in various ways. For example, the 2001 anthrax‐attack letters and lone‐wolf terrorism created alternative intersections of perpetrators with victims.     

Temporal Point Pattern Analysis of Human Activities Using GIS Methods: A Case Study of Library Visiting Activities in Chengdu City,China

This article aims to develop a new type of temporal pattern analysis—temporal point pattern analysis (TPPA)—by treating the distribution of activities as a point pattern on a two-dimensional plane using the start time and end time of activities as axes. Geographic information systems (GIS) methods, which are originally used in spatial point pattern analysis in GIS, are introduced to support TPPA. This article presents a case study to understand the temporal patterns of the library visiting activities of university students using a four-week smart card data set in Chengdu City, China. Several methods from GIS are applied, including the measurement of mean centers, kernel density, nearest neighbor distances, and optimized hot spot analysis. Results show that the GIS methods can reveal a lot of information on the temporal pattern of activities, thereby proving the reasonability of the proposed TPPA of activities. Key Words: GIS, human activities, library visiting, smart card data, visualization.     

A rain on snow climatology and temporal analysis for the eastern United States

ABSTRACT

Rain-on-snow (ROS) has the potential to produce devastating floods by enhancing runoff from snowmelt. Although a common phenomenon across the eastern United States, little research has focused on ROS in this region. This study used a gridded observational snow dataset from 1960–2009 to establish a comprehensive seasonal climatology of ROS for this region. Additionally, different rain and snow thresholds were compared while considering temporal trends in ROS occurrence at four grid cells representing individual locations. Results show most ROS events occur in MAM (March-April-May). ROS events identified with rainfall >1 cm are more frequent near the east coast and events identified with >1 cm snow loss are more common in higher latitudes and/or elevations. Decreasing trends in DJF (December-January-February) ROS events were identified near the coastal areas, with increasing trends in the northern portion of the domain. Significant decreasing trends in MAM ROS are likewise present on a regional scale. Factors playing a role in snowpack depth and rainfall, such as movement of storm tracks in this region, should be considered with future work to discern mechanisms causing the changes in ROS frequency.     

Constraints of Housing Age and Migration on Residential Mobility

This paper investigates the role of housing age in constraining residential mobility, measured as the percent of households that have moved into their homes in the past 15 months. The leading explanation for why mobility rates differ so much among regions of the United States has been the overall level of growth. The present analysis shows that the growth effect operates through both the newness of population (migration) and the newness of housing available for occupancy by all local residents. The posited explanation for this housing age effect is that progressively older units contain increasingly settled occupants, yielding fewer opportunities for in-movers in areas with older housing. It is empirically demonstrated that households in older housing have lower likelihood of recent mobility even after controlling for age, tenure, migration status, and state location of residence. The analysis reveals the temporal interdependency of mobility, migration, person age, and housing age.     

中美巴印过去300年耕地时空变化的比较研究

本文利用长时间序列数据,对中、美、巴、印四国过去300 年耕地时空变化特征及驱动因素进行了比较分析。结果表明:①四国耕地总量在过去300 年均呈持续增长态势。中国和印度土地垦殖历史悠久,其中,中国在1700-1980s 耕地面积增加了68.21×10⁴ km²,印度在1700-2000 年增加了131.28×10⁴ km²,为中国的1.92 倍;美国和巴西虽然农业起步较晚,但发展迅猛,其中,美国在1700-1950 年的250 年间耕地面积增长了190.87×10⁴ km²,分别是中国、印度增量的2.80 倍和1.46 倍;巴西在1700-2000 年增加了64.57×10⁴ km²,其中近百年的增量为62.82×10⁴ km²,超过了同期其他三国的增加量。②从空间格局变化特征看,近300 年来,中国和印度均是在已有耕地分布格局的基础上向高原及山地丘陵地区扩展;而美国在“西进运动”的影响下,耕地大规模向中西部拓殖;巴西随着向北西部开发的推进,北部、西部地区的耕地急剧增加。③过去300 年推动四国土地垦殖发展最直接的驱动因素是国家政策,但就根本驱动因素而言,中国和印度是人口,而美国和巴西则是国家财政;在农技发展取向方面,中国和印度选择了精耕细作以提高土地生产率;而美国和巴西则选择了机械化以提高劳动生产率。     

中国对美国州层面直接投资时空演变与驱动因素探究——以得克萨斯州为例

改革开放以来,中国的外商直接投资经历了从“引进来”到“走出去”的发展历程。2016与2017年,中国对外直接投资（COFDI）流量与存量先后跃升至全球第二位,由外商直接投资吸收国转变为世界主要对外直接投资国之一。在中美双方经贸合作伙伴关系持续深入背景下,美国已成为中国对外直接投资首位东道国。投资是落于具体地域的,不同尺度地域投资环境的差异性是导致中国对美直接投资时空分异的重要原因。立足于中国（投资母国）视角,以美国州内各选区为研究地域尺度,利用空间自相关等方法,对美国典型州——得克萨斯州的中国对外直接投资的时空格局与演变特征进行了探讨,同时引入面板数据计量模型对COFDI在得州内各选区间投资驱动因素进行了实证分析。结果表明：(1)得州内COFDI存量持续增长,但阶段性特征明显;(2)得州内COFDI以国有企业并购为主,且主要集中在能源产业;(3)COFDI州内集聚程度较弱,局部选区间多呈现出相异属性集聚特征;(4)市场规模、劳工人数、交通通达性、华人移民数对COFDI具有正向促进作用,劳动成本、教育水平、税率、经济密度对COFDI具有不同程度的负向作用。研究结果可为中国政府、跨国企业在...     

Defining the Historical Northeastern Forested Boundary of the Great Plains Grasslands in the United States

The Great Plains is the grasslands of the central United States, but precise delineation of this region has evaded agreement due to the transition between Great Plains grasslands and forests of the eastern United States. After comparing Great Plains delineations in readily available geographic information system layers, I established a northeastern boundary using evidence from historical tree surveys during the 1800s. Additionally, I described tree presence within the Great Plains over time and potential drivers of change. The definition documented here diverges from others by including most of Iowa and part of Illinois, and even small sections in Indiana and Wisconsin, but excluding Missouri due to regular tree presence overall at landscape scales of ecological subsections. In this definition, the Great Plains had an extent of 2.29 million km² in fifteen states, including Indiana and Wisconsin, and 2.19 million km² after removal of open forests in Oklahoma and Texas. Tree presence occurs within the Great Plains and tree encroachment is not a new process; however, tree encroachment is increasing in the Great Plains, which causes a decrease in the grasslands region. Nevertheless, clarifying the historical eastern boundary provides a solution to the problem of competing versions of the Great Plains region. Key Words: ecotone, prairie, savanna, tree encroachment.     

Temporal and spatial trends of precipitation and river flow in the Yangtze River Basin, 1961–2000

The suspected impact of climate warming on precipitation distribution is examined in the Yangtze River Basin. Daily precipitation data for 147 meteorological stations from 1961–2000 and monthly discharge data for three stations in the basin have been analyzed for temporal and spatial trends. The methods used include the Mann–Kendall test and simple regression analysis. The results show (1) a significant positive trend in summer precipitation at many stations especially for June and July, with the summer precipitation maxima in the middle and lower Yangtze River basin in the 1990s; (2) a positive trend in rainstorm frequency that is the main contributor to increased summer precipitation in the basin; and (3) a significant positive trend in flood discharges in the middle and lower basin related to the spatial patterns and temporal trends of both precipitation and individual rainstorms in the last 40 years. The rainstorms have aggravated floods in the middle and lower Yangtze River Basin in recent decades. The observed trends in precipitation and rainstorms are possibly caused by variations of atmospheric circulation (weakened summer monsoon) under climate warming.     

Exploring the Impact of Contextual Information on Student Performance and Interest in Open Humanitarian Mapping

The opportunity to engage university students in authentic, open humanitarian mapping raises important questions about how to guide the quality and productivity of volunteer spatial contributions while providing a valuable learning experience. It presents the unique chance to pique new mappers’ interest, satisfaction, and confidence in spatial technologies in particular, and technology in general, as well as pique their interest in the people and places that are served by the humanitarian mapping projects. This article shares the findings of a study that explores the importance of sharing authentic contextual information about the purpose of the humanitarian mapping task. Two groups of beginner mappers were given mapping tasks, with only one group being provided details on the purpose. Comparisons were made on their respective performance and changes in affective response to a series of questions about technology, education, good citizenship, and empathy. Measures of the quantity and quality of spatial data produced; their respective levels of interest, satisfaction, and confidence in technology; and affective responses before and after mapping show the relative effects of contextual information. Results provide insights about the potential effectiveness of authentic instruction on the performance of mapping as well as the potential effect on mappers themselves. Key Words: citizenship, data quality, empathy, humanitarian mapping, volunteered geographic information.     

An exploratory spatial data analysis of low birth weight prevalence in Georgia

Low birth weight (LBW), defined as a live birth weighing less than 2500 g, is a significant public health problem in the United States, but the complex nature of the etiology of this problem is not fully understood. Moreover, significant disparities in LBW prevalence are well documented among certain populations, particularly in minority and underserved communities. The identification of spatial patterns of LBW prevalence is a critical first step in a more complete understanding of the epidemiology of this public health challenge and these techniques are instrumental in designing valid observational and analytical studies to more fully study the problem. This paper examines the spatial patterns of LBW prevalence, as well as the presence of spatial clusters in the State of Georgia at both the county and census tract levels. Unadjusted and empirical Bayes smoothed LBW rates were mapped to visualize the spatial variation of LBW rates, and the Moran’s I statistic and the Local Indicator of Spatial Association (LISA) statistic were computed to assess the degree of spatial dependence in the LBW rates. Results revealed marked geographical variation in LBW prevalence in Georgia in 2000. In addition, these data validate the significant disparity (two-fold difference) between white and black racial subgroups as documented in the literature. Trends associated with positive and negative spatial autocorrelations illustrated variation with respect to race. Limitations of data and methods, as well as plans for utility of the results of this study for further investigation were discussed.     

Spatial spillover and the socio-ecological determinants of diabetes-related mortality across US counties

The spatial structure of diabetes-related mortality in US counties is evident from previous studies. However, it is not clear if spatial variation in diabetes-related mortality is associated with spatial variation in socioecological factors. We analyze the spatial spillover effect of changes in socioeconomic gradients (education, employment, household income), retail food environments, and access to health care, on diabetes-related mortality rates across the United States. Seven-year aggregates of multiple cause mortality data from the CDC WONDER compressed mortality database were merged with several sources of county-level data to examine mortality clusters, factors associated with the clusters, and spatial spillover effects in 3109 continuous US counties. The results suggest that high diabetes-related mortality cluster counties are located throughout the Southern Plains, Southeastern, and Appalachian regions. Lower socioeconomic status, a high density of fast food restaurants, a lack of access to grocery stores, a high proportion of Blacks, and low physical activity characterize high diabetes-related mortality rates clusters. The impacts from improvements in socioeconomic gradients and the retail food environment in neighboring counties spill over, and reduce the diabetes-related mortality rate in a particular county. This result implies that improvements in socioeconomic status and access to healthy food would significantly reduce diabetes-related mortality rates in contiguous US counties.     

Network Topology and City Accessibility of the Commercial Internet

The rapid growth in this decade of World Wide Web access through the Internet is supported by a complex matrix of telecommunications infrastructure. This paper presents an overview of the history of the Internet and recent efforts to measure its structure and performance, and examines the spatial organization of the commercial Internet backbone. The research presented in this paper differs from previous Internet measurement work in that we apply network analysis methods to evaluate Internet connectivity. Transportation network analysis techniques are applied to measure 1) connectivity of individual service provider networks and 2) accessibility of cities to Internet service. The results reveal many different strategies implemented by service providers in network design as well as large differences in levels of accessibility of cities and regions in the United States. There is also an apparent disparity between population and city accessibility to the Internet.     

中美科技竞争力比较研究

在界定国家科技竞争力内涵的基础上,从科技人力资源竞争力、科技财力资源竞争力、科学研究竞争力、技术创新竞争力和科技国际化竞争力五个方面建构了国家科技竞争力评价指标体系,从而详细对比了中美两国在科技发展上的差异。研究发现,无论是整体竞争力还是科技投入、科学研究、技术创新、科技国际化等单项竞争力,中国都与美国都存在不小差距,中国科技竞争力虽然加速提升,但仍显著落后于美国,中国科技发展任重道远。基于中美两国科技竞争力的现状对比及趋势研判,本文认为：中国进一步提升科技竞争力,加快建设世界科技强国,既需要对标先进、参照一流,进一步深化开放式创新,充分学习和借鉴美国等科技强国的成功经验,更需要立足自身、正视短板,坚持科技创新与制度创新双轮驱动、发展速度和创新质量有机统一、自主创新与开放创新相互促进,着力推动以质量和效益为核心的创新战略,加强基础科学研究,突破关键核心技术,集聚高端科创人才,以实现国家科技竞争力的持续稳步增强。     

高速公路流的距离衰减模式与空间分异特征——基于福建省高速公路收费站数据的实证研究

交通流是社会经济空间联系的直观反映,其距离衰减规律对空间秩序的形成与演化意义重大。利用2016年10月份的福建省高速公路收费站数据,以县区为基本单位,识别高速公路流O-D矩阵;在此基础上,利用空模型法模拟省和县区2个尺度上高速公路流的距离衰减规律,并结合空间分析和相关分析法,探讨高速公路流距离衰减规律的空间分异特征与规律。结果显示,①高速公路流主要集中在0~200 km与0~200 min区段,较好地契合了公路运输的经济半径与交通流的时空断裂特征;②省域层面上,高速公路流随距离的增加有显著的衰减趋势,当采用路网距离、幂律型衰减函数时,距离衰减系数为2.674,显著高于常规所选数值2;③不同县区高速公路流的距离衰减速度在空间上呈显著的圈层模式,与高速公路流的空间分布形成较好的耦合关系;④距离衰减规律内生于社会经济空间联系格局,不仅影响空间秩序的形成与演化,也会受空间秩序演化的影响,一定条件下,节点的对外社会经济空间联系强度会随节点规模、人口与经济密度的提高以及区位条件的优化形成自我加速的反馈过程,形成循环累积效应。