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941.
The HIV/AIDS epidemic remains a major public health issue across the globe, and it is of particular concern in sub-Saharan Africa. Utilization of sexual and reproductive health (SRH) services can significantly impact HIV prevention, transmission, and treatment. SRH service utilization may be determined by individual characteristics, such as education and economic status, but also by the location and accessibility of health care facilities. Using population-based survey data, this study applies exploratory spatial analysis techniques to examine spatial patterns of SRH service utilization among rural married women in southern Mozambique. Clustering among those using services is found as are spatial associations, indicating significant spatial variability in the utilization of health services. The findings provide valuable insights for current and future health care program planning and configuration. 相似文献
942.
943.
Chih-Chieh Lu Jin-Hung Hwang C. Hsein Juang Chih-Sheng Ku Zhe Luo 《Engineering Geology》2009,108(1-2):24-35
This paper presents a framework for assessing the probability of exceeding a specified liquefaction-induced settlement at a given site in a given exposure time. This framework deals not only with the effect of liquefaction (in terms of settlement) but also with probabilistic characterization of all possible ground motions at a given site (in terms of a joint distribution of amax and Mw). Additionally, a new concept, referred to herein as liquefaction-induced settlement hazard curve, is introduced for assessing the annual rate of settlement exceedance at a given site. This settlement hazard curve concept has the potential to be a very useful tool in the field of geotechnical earthquake engineering. Satisfactory results are obtained in the demonstration examples analyzed with the proposed framework. Whereas the proposed framework is simple and effective, further refinements to this framework, especially on the treatment of epistemic uncertainty, are warranted. 相似文献
944.
Mark Chun Richard Wilson Remy Avila Tim Butterley Jose-Luis Aviles Don Wier Sam Benigni 《Monthly notices of the Royal Astronomical Society》2009,394(3):1121-1130
We present the results of an 18-month study to characterize the optical turbulence in the boundary layer and in the free atmosphere above the summit of Mauna Kea in Hawaii. This survey combined the Slope-Detection and Ranging (SLODAR) and Low-Layer SCIntillation Detection And Ranging (SCIDAR) (LOLAS) instruments into a single manually operated instrument capable of measuring the integrated seeing and the optical turbulence profile within the first kilometre with spatial and temporal resolutions of 40–80 m and 1 min (SLODAR) or 10–20 m and 5 min (LOLAS). The campaign began in the fall of 2006 and observed for roughly 50–60 h per month. The optical turbulence within the boundary layer is found to be confined within an extremely thin layer (≤80 m), and the optical turbulence arising within the region from 80 to 650 m is normally very weak. Exponential fits to the SLODAR profiles give an upper limit on the exponential scaleheight of between 25 and 40 m. The thickness of this layer shows a dependence on the turbulence strength near the ground, and under median conditions the scaleheight is <28 m. The LOLAS profiles show a multiplicity of layers very close to the ground but all within the first 40 m. The free-atmosphere seeing measured by the SLODAR is 0.42 arcsec (median) at 0.5 μm and is, importantly, significantly better than the typical delivered image quality at the larger telescopes on the mountain. This suggests that the current suite of telescopes on Mauna Kea is largely dominated by a very local seeing either from internal seeing, seeing induced by the flow in/around the enclosures, or from an atmospheric layer very close to the ground. The results from our campaign suggest that ground-layer adaptive optics can be very effective in correcting this turbulence and, in principle, can provide very large corrected fields of view on Mauna Kea. 相似文献
945.
C. Michael Costanzo 《The Professional geographer》1983,35(2):158-165
Concepts relevant to statistical inference testing are discussed within a framework which contrasts conventional methodology with current trends in statistics. The latter are emphasized as having the quality of being less restrictive than the former. To show this quality, randomization testing is described and an example presented. Also described is a nonparametric technique known as QAP, which is particularly versatile. Optimism is expressed about the potentiality of such procedures for geographic research. 相似文献
946.
Compositional data, consisting of vectors of proportions summing to unity such as the geochemical compositions of rocks, have proved difficult to analyze. Recently, the introduction of logistic and logratio transformations between the d-dimensional simplex and Euclidean space has allowed the use of familiar multivariate methods. The problem of how to model and analyze measurement errors in such data is approached through the concept of a perturbation of a composition. Such modeling allows investigation of the role of rescaling, quantification of measurement error, analysis of observor error, and assessment of the effect of measurement error on inferences. 相似文献
947.
948.
本文通过对NOAA-10,11两颗气象卫星1989年5月至1990年4月的云图资料,在作等经纬度投影处理和定标,定位订正的基础上,利用红外域值方法,对东经99°—104°,北纬23.5°—28.5°云南区域内31个天文台址侯选点的云量进行了统计和计算,得到几个云量最少的候选点。此外,我们还对卫星云图CC≤3的晴日晴夜和三十年地面气象观测资料中CC≤2的晴天数作了相关分析,发现它们之间具有很好的相关性。云图和地面资料综合分析表明:(1)永仁的俄尼刀博,姚安的老官山,元谋气象区的白露,祥云的大营后山,宾川的小鸡山,华坪的蘑菇山,宁蒗的他尔布子都是较理想的候选点。(2)俄尼刀博,老官山和白露可用夜(CC≤3)预计可超过250夜。因此应列为下一步选址的重点。 相似文献
949.
The study of localized failure under controlled conditions can be accomplished within a laboratory setting with the University of Minnesota plane-strain compression apparatus. The device provides an opportunity to observe shear faulting and to compare displacements from acoustic emission (AE) sources with global measurements. A biaxial compression test on a sandstone specimen was performed with monitoring of AE. The plane-strain test showed that the shear fault was not formed until after peak load. Compaction of the shear fault was observed from the axial and lateral measurements of displacement and the orientation of the failure plane. The AE events were modeled as displacement discontinuities. The complicated deconvolution process for the transducer transfer function was eliminated by using a simplified calibration procedure. The sources of the postpeak events were characterized as being caused predominantly by slip in the direction of the global failure plane, although components of displacement associated with closing were identified. To provide an order of magnitude estimate of the slip, the field observation of a 10−4 strain drop over the seismic area was assumed. The tangential displacement from 110 AE events was estimated to be 0.01 mm. During the same period of time, the displacement along the shear fault from global measurements was 0.03 mm. 相似文献
950.
J.L. Rodríguez-Zúñiga C. Ortiz-Alemán G. Padilla R. Gaulon 《Soil Dynamics and Earthquake Engineering》1997,16(3):223-234
Among the class of global optimization techniques, which includes Monte Carlo and simulated annealing methods, the Genetic Algorithms constitute a new class of methods to solve highly non-linear optimization problems. The issue has generated considerable interest in the field of artificial intelligence, and recently, in some multi-parameter optimization geophysical problems. In this study, we explore the applicability of genetic algorithms to the inversion of high resolution ground inclination measurements produced by known loads placed at known distances. Our objective is to find a model for dynamic properties of the subsoil such as shear and compressional wave velocities and depth distributions of the uppermost strata, which are related to elastic moduli. Three parameters are needed for describing elastic isotropic horizontally homogeneous media: mass density ρ and Lame constants λ and μ or mass density and P-wave and S-wave velocities. In general, the choice of parameters is not always a simple matter. In fact, although theoretically equivalent, if they are not adequately chosen, the numerical algorithms in the inversion can be inefficient.Ground inclination surveys were performed at the virgin Texcoco Lake, near Mexico City, and at the European Synchrotron radiation facility (ESRF) of Grenoble, France. From both sets of data we study the feasibility of applying genetic algorithms to rapidly and effectively explore the model space to find an optimal model for the shallow structure under study. Forward solution of vertical and radial displacements in a layered medium, under static loads, is calculated by means of the stiffness matrix approach (Kausel, E. & Roesett, J. M. Stiffness matrices for layered soil. Bulletin of the Seismological Society of America, 1981, 71(6), 1743–1761.) Comparisons with results from common established techniques such as seismic wave refraction profiles, cone resistance values and inversion of surface wave dispersion curves were used for validation purposes. Our procedure represents a fast and accurate alternative method to infer the shallow elastic parameters in surficial soils. 相似文献