共查询到20条相似文献，搜索用时 31 毫秒
1.
Kasto 《The Indonesian journal of geography》1980,10(39):17-25
This study elaborates on Indonesian fertility differentials based on the average number of children ever born or late births per woman. Other studies have shown that the relationship between fertility and economic class does not show a consistent pattern, being sometimes negative and sometimes positive. In the areas of Mojolama and Kedung Miri, characteristics such as occupation and economic status differ, but the relationship between age and economic status of the family was positive in both. In general, socioeconomic conditions in Majolama were better than in Kedung Miri but fertility levels were about the same at 3.6 children ever born/ever married woman in Mojolama and 3.5 in Kejung Miri, while the average of completed family size was the same, 4.8. There was a finding that women in higher economic classes tend to have a higher average number of children compared to those in lower economic classes. 相似文献
2.
《Urban geography》2013,34(7):724-738
Determining an accurate depiction of population distribution for urban areas in order to develop an improved "denominator" is important for the calculation of higher-precision rates in GIS analyses, particularly when exploring the spatial dynamics of disease. Rather than using data aggregated by arbitrary administrative boundaries such as census tracts, we developed the Cadastral-Based Expert Dasymetric System (CEDS), an interpolation method using ancillary information to delineate areas of homogeneous values. This method uses cadastral data, land-use filters, modeling by expert system routines, and validation against various census enumeration units and other data. The CEDS method is presented through a case study of asthma hospitalizations in the borough of the Bronx in New York City, in relation to proximity buffers constructed around major sources of air pollution. The analysis using CEDS shows that asthma hospitalization risk due to proximity to pollution sources is greater than previously calculated using traditional disaggregation methods. 相似文献
3.
The geomorphology of the martian valley networks is examined from a hydrological perspective for the compatibility with an origin by rainfall, globally higher heat flow, and localized hydrothermal systems. Comparison of morphology and spatial distribution of valleys on geologic surfaces with terrestrial fluvial valleys suggests that most martian valleys are probably not indicative of a rainfall origin, nor are they indicative of formation by an early global uniformly higher heat flow. In general, valleys are not uniformly distributed within geologic surface materials as are terrestrial fluvial valleys. Valleys tend to form either as isolated systems or in clusters on a geologic surface unit leaving large expanses of the unit virtually untouched by erosion. With the exception of fluvial valleys on some volcanoes, most martian valleys exhibit a sapping morphology and do not appear to have formed along with those that exhibit runoff morphology. In contrast, terrestrial sapping valleys form from and along with runoff valleys. The isolated or clustered distribution of valleys suggests localized water sources were important in drainage development. Persistent groundwater outflow driven by localized, but vigorous hydrothermal circulation associated with magmatism, volcanism, impacts, or tectonism is, however, consistent with valley morphology and distribution. Snowfall from sublimating ice-covered lakes or seas may have provided an atmospheric source of water for the formation of some valleys in regions where the surface is easily eroded and where localized geothermal/hydrothermal activity is sufficient to melt accumulated snowpacks. 相似文献
4.
Gregory A. Pope 《The Professional geographer》1995,47(4):375-387
Quartz is regarded as one of the minerals most resistant to chemical weathering. Nevertheless, quartz does weather under certain conditions. Several geographic phenomena, including downstream sorting of fluvial sediments, the distribution of loess, and the absence of silica in tropical soils, may be directly or indirectly related to quartz weathering. Weathering may impact the use of quartz in geographic applications of geochronology and paleoenvironmental analysis. This paper defines the molecular-scale mechanisms of chemical weathering in quartz, and presents the first examination of quartz weathering in the terrestrial environment using high resolution transmission electron microscopy (HRTEM). HRTEM images illustrate crystalline disintegration, or amorphization, of exterior surfaces and internal fractures of quartz sand grains collected from tills of the Eastern Sierra Nevada, California. Of several alternative mechanisms, in situ hydration of the crystalline matrix is the most plausible for quartz amorphization. Scale and mineral structure appear to be prominent factors in quartz amorphization; microenvironment and weathering rates may also be significant, but data are insufficient to make more precise generalizations. 相似文献
5.
6.
Rushdoony HA 《The Journal of geography》1978,77(6):221-224
Purpose of this paper is to present a model for teaching fourth grade children some aspects of the population geography of California from a nontextual approach. The objective is to interest and instruct children in the mobility of the people, and on the reasons why so many families have moved to California from other states. Students should be alerted not only to internal migration problems, but to the excess of births over deaths. Materials necessary for the lessons are transparencies, overhead projector, marking pencils, chalk and chalkboard. After showing the students that California population has approximately doubled every 20 years, the students should be encouraged to find reasons explaining why people have moved to the state, should be able to categorize those reasons under the terms industrial/manufacturing, agricultural, urban or recreational, should learn how to plot population distribution on a California regional outline map, and should attempt to explain why certain parts of California are more popular than others. The teaching model described in this paper may be replicated with modfications for any grade level and area of study. 相似文献
7.
This study investigates the diversity of immigrant populations and their spatial residential patterns at the census tract level within twenty‐nine counties of the Atlanta Metropolitan Statistical Area (MSA), using 2013 American Community Survey (ACS) five‐year estimates summary data from 2008–2012. Correlations coefficient analyses with local job opportunities, education level, and English proficiency and the presence of foreign‐born populations are also discussed. We find that immigrants have different patterns of settlement depending on their place of birth and region of origin. Local job opportunities, dominant language at home, and education levels also relate to the distribution of foreign‐born populations. Further research opportunities concerning differential settlement are discussed. 相似文献
8.
Fabrice R. Fontaine Guilhem Barruol réa Tommasi Götz H. R. Bokelmann 《Geophysical Journal International》2007,170(3):1262-1288
Upper-mantle flow beneath the South Pacific is investigated by analysing shear wave splitting parameters at eight permanent long-period and broad-band seismic stations and 10 broad-band stations deployed in French Polynesia from 2001 to 2005 in the framework of the Polynesian Lithosphere and Upper Mantle Experiment (PLUME). Despite the small number of events and the rather poor backazimuthal coverage due to the geographical distribution of the natural seismicity, upper-mantle seismic anisotropy has been detected at all stations except at Tahiti where two permanent stations with 15 yr of data show an apparent isotropy. The median value of fast polarization azimuths (N67.5°W) is parallel to the present Pacific absolute plate motion direction in French Polynesia (APM: N67°W). This suggests that the observed SKS fast polarization directions result mainly from olivine crystal preferred orientations produced by deformation in the sublithospheric mantle due to viscous entrainment by the moving Pacific Plate and preserved in the lithosphere as the plate cools. However, analysis of individual measurements highlights variations of splitting parameters with event backazimuth that imply an actual upper-mantle structure more complex than a single anisotropic layer with horizontal fast axis. A forward approach shows that a two-layer structure of anisotropy beneath French Polynesia better explains the splitting observations than a single anisotropic layer. Second-order variations in the measurements may also indicate the presence of small-scale lateral heterogeneities. The influence of plumes or fracture zones within the studied area does not appear to dominate the large-scale anisotropy pattern but may explain these second-order splitting variations across the network. 相似文献
9.
Joseph R. Oppong Curtis J. Denton Patrick K. Moonan Stephen E. Weis 《The Professional geographer》2007,59(4):478-491
Regardless of destination, immigrants arrive with health profiles typical of people in their previous surroundings. Thus, immigrants change the epidemiological profile of destination communities, and immigrant neighborhoods may represent islands of infectious disease. Genotyping has emerged as a useful surveillance tool to track the spread of disease at the molecular level. Yet the spatial distribution of infectious disease at the molecular level associated with migration and immigrant neighborhoods has received little attention. Using molecular genotyping to characterize M. tuberculosis isolated from tuberculosis cases, this article analyzes spatial variations of unique molecular M. tuberculosis strains by zip code in Tarrant County, Texas. The results suggest that immigrant neighborhoods have higher rates of unique isolates of tuberculosis (suggestive of remote transmission) compared to neighborhoods occupied by the native‐born. Neighborhoods dominated by the native‐born have higher rates of clustered isolates (suggestive of recent transmission). Therefore, in addition to being culturally distinct, immigrant neighborhoods may also be pathogenically distinct from surrounding neighborhoods. 相似文献
10.
中国民间抱养行为由来已久,家庭送养的决策将完全改变儿童的生存和发展的轨迹。囿于送养的隐蔽性和复杂性,且相关研究匮乏,亟需系统性的剖析。文章基于公益平台寻亲数据,运用社会网络、空间分析、数理统计以及地理探测器的方法,探究1981—2010年家庭送养的时空分异特征,并进一步归纳送养决策的流程及原因机制。结果表明：1）送养主体为未满1周岁女童。2）送养人数在时间上呈现“先增后减”的倒“U”型分布,在空间上主要分布在中国东部、中部以及川渝地区。3）家庭送养原因以经济贫困为主,违反生育政策的影响次之。当家庭面临狭小的生育空间时,重男轻女的思想会被强化。4）地理探测器结果揭示,人口因素是影响送养空间分异最主要的原因,自然灾害、计划生育和经济因素在不同时期产生较大影响。5）基于理性选择理论提出了多尺度下的家庭送养的影响机制,认为家庭在作理性送养决策时,往往遵循生存理性、经济理性、制度理性以及社会理性的原则。 相似文献
11.
Quantitative geomorphological analysis of drumlins in the Peterborough drumlin field,Ontario, Canada
John C. Maclachlan Carolyn H. Eyles 《Geografiska Annaler: Series A, Physical Geography》2013,95(2):125-144
Drumlins are enigmatic subglacial landforms that have been interpreted to form by a number of processes, including incremental accumulation of till, erosion of previously deposited sediment, catastrophic meltwater floods, and sediment deformation. However, relatively little is known about the controls on drumlin formation, such as spatially variable glacial processes or substrate characteristics, and how these controls may be identified from variations in drumlin morphology within a single drumlin field. This paper explores a computational method that allows identification of drumlins and extraction of their morphological characteristics from existing topographic digital data for a portion of the Peterborough drumlin field in Ontario, Canada. Spatial and non‐spatial analysis of the form and distribution of drumlins across the study area identifies drumlin characteristics such as size, elongation ratio, symmetry and long axis orientation and shows that drumlins are not randomly distributed across the region and their form characteristics have distinct regional trends. Kernel density analysis is used to identify the regional trends in drumlin characteristics. Factors that appear to influence the form and distribution of drumlins in the study area include sediment thickness, length of time beneath the ice, ice velocity and direction of ice movement. The distribution of particularly well developed asymmetric and elongate drumlins coincides with the location of a broad bedrock low and is interpreted to identify the former location of a fast‐flowing ice stream. 相似文献
12.
C2C服装店铺信用等级的规模分布及其影响因素——以江浙沪地区为例 总被引：1，自引：0，他引：1
通过搜集与计算得到江浙沪地区各城市淘宝男装、女装、童装及服装店铺整体的信用等级,同时借助集中程度分析、位序—规模法则及回归分析,探讨了该地区淘宝服装店铺信用等级的规模分布特征及其影响因素。结果表明：1）除童装外,江浙沪地区淘宝服装店铺整体及男装、女装店铺,其信用等级的位序—规模分布满足齐夫法则;2）江浙沪地区淘宝服装店铺信用等级的空间分布形态满足对数正态分布模式;3）淘宝服装店铺信用等级的无标度区涵盖了江浙沪地区绝大部分城市,其规模分布结构相对优化;4）淘宝服装店铺的信用等级受信息化水平、物流指数、基础规模实力、文化教育水平、经济发展水平和区位优势度等因素的综合影响,但当地服装产业的工业集中度未能影响淘宝服装店铺的信用等级。 相似文献
13.
Summary. Palaeomagnetic data relating to secular variation, westward drift, non-dipole field scatter, field intensities and polarity transitions are considered together in an attempt to improve our understanding of the geodynamo. An attempt is then made to interpret these data in the light of magnetohydrodynamic theory. It is suggested that polarity transitions are not characterized by significant periods of convection stasis but that dynamic processes appear to be acting throughout. Phenomena such as variable westward drift rates are explained in terms of non-linear effects relating to the magnetic field intensity. Several lines of evidence suggest that the Lorentz force is a significant body force within the Earth's core and cannot be treated as a perturbation. However, it is also suggested that the Lorentz force may become insignificant during polarity transitions, particularly during that part of a transition when the intensity is reduced and the magnetic field is predominantly non-dipolar. 相似文献
14.
Cardiovascular diseases (CVDs) are a leading cause of mortality in the US. Rates of mortality vary spatially and demographically, influenced not only by individual patient characteristics but also by levels of accessibility to hospital services and facilities. In 2000, Kentucky ranked third in the nation for heart-related deaths. The purpose of this paper is to assess geographical accessibility and service utilization related to ambulatory care sensitive CVDs in Kentucky. This study utilizes the Kentucky Hospital Discharge Database to evaluate service utilization and the Compressed Mortality File to examine mortality related to CVDs. A spatial statistical comparison of the geographical distribution of service usage and travel time to hospitals assists in assessing the relationship between accessibility and health. Our findings suggest that the distribution of utilization and mortality is geographically variable. People living in rural areas travel further to services; populations residing more than 45 min from health facilities are more likely to be socially and economically marginalized. Spatial clustering of high rates of hospital utilization occurs in areas with lower accessibility. 相似文献
15.
利用1961~2010年吉林省雾日统计资料,对吉林省雾日的时空分布特征、变化趋势进行了详细分析,并分析了雾日变化的原因。结果表明：近50 a来,吉林省年和四季雾日的空间分布均呈东南部地区多、西部地区少的分布特征;雾日季节变化特征表现为8~9月多,10月至次年5月少,西部和中部地区雾日数月季变化呈现双峰型,东南部和东部地区呈现单峰型;雾大多数开始于夜间21时至次日早晨09时,结束于夜间22时至次日午后13时,持续时间多在6 h以下。近50 a来,除了春季雾日没有明显变化外,全省平均及各区域年和四季雾日均呈减少趋势;在2000年前后雾日数发生了一次明显的突变。雾日空间分布与海拔高度有密切关系;雾日趋于减少有人类活动导致的“热岛效应”、“干岛效应”、气溶胶密度加大等原因,也有气候趋于暖干化的自然原因。 相似文献
16.
17.
18.
本文根据1966—1975,5—9月候降水资料,对夏季风期间我国候降水的区域分布及季节变化进行分析,主要结果如下:1.候平均10毫米等雨量线的南北位移,随着夏季风进退而变化,此线在7—8月位置与夏季风北界基本一致。2.大雨区自南向北位移,只有两个时段明显,7月1候以前大雨区位于30°N以南,7月5候大雨区北移至40°N,这种现象仅在我国东部地区明显,西部地区不明显。3.根据我国各地区候降水分布特征,可将降水分为五个类型。 相似文献
19.
利用1961-2010年吉林省雾日统计资料,对吉林省雾日的时空分布特征、变化趋势进行了详细分析,并分析了雾日变化的原因。结果表明：近50 a来,吉林省年和四季雾日的空间分布均呈东南部地区多、西部地区少的分布特征;雾日季节变化特征表现为8-9月多,10月至次年5月少,西部和中部地区雾日数月季变化呈现双峰型,东南部和东部地区呈现单峰型;雾大多数开始于夜间21时至次日早晨09时,结束于夜间22时至次日午后13时,持续时间多在6 h以下。近50 a来,除了春季雾日没有明显变化外,全省平均及各区域年和四季雾日均呈减少趋势;在2000年前后雾日数发生了一次明显的突变。雾日空间分布与海拔高度有密切关系;雾日趋于减少有人类活动导致的“热岛效应”、“干岛效应”、气溶胶密度加大等原因,也有气候趋于暖干化的自然原因。 相似文献
20.
以自行研制的恒流式静态应变仪(中国专利号:88212764.0)为主机的HP-2型滑坡遥测系统,用作测值远传和分散设点集中遥测数据。本系统配接PC-1500A或IBM PC/XT计算机,可构成滑坡监测系统;它既能控制多点巡回检测、定点检测和通道号显示,亦可控制应变仪作半桥或全桥测量,又能控制采样时间等。1987—1990年运行结果表明,本遥测系统相当稳定可靠。 相似文献