Modeling Spatial Accessibility of Immigrants to Culturally Diverse Family Physicians     

Lu Wang  Deborah Roisman 《The Professional geographer》2013,65(1):73-91

This article uses accessibility as an analytical tool to examine health care access among immigrants in a multicultural urban setting. It applies and improves on two widely used accessibility models—the gravity model and the two-step floating catchment area model—in measuring spatial accessibility by Mainland Chinese immigrants in the Toronto Census Metropolitan Area. Empirical data on physician-seeking behaviors are collected through two rounds of questionnaire surveys. Attention is focused on journey to physician location and utilization of linguistically matched family physicians. Based on the survey data, a two-zone accessibility model is developed by relaxing the travel threshold and distance impedance parameters that are traditionally treated as a constant in the accessibility models. General linear models are used to identify relationships among spatial accessibility, geography, and socioeconomic characteristics of Mainland Chinese immigrants. The results suggest a spatial mismatch in the supply of and demand for culturally sensitive care, and residential location is the primary factor that determines spatial accessibility to family physicians. The article yields important policy implications.  相似文献   

Beyond “Lawn People”: The Role of Emotions in Suburban Yard Management Practices     

Edmund M. Harris  Deborah G. Martin  Colin Polsky  Lillian Denhardt  Abigail Nehring 《The Professional geographer》2013,65(2):345-361

Many recent studies have applied satellite remote sensing data to large-scale hydrologic and biospheric modeling. It is widely accepted that the thermal infrared observations from the Advanced Very High Resolution Radiometer (AVHRR) have the potential to estimate land surface conditions, such as surface temperature, near surface air temperature, and near surface water vapor. In this study, algorithms to estimate all three variables are presented and applied to an area covering the state of Oklahoma for a six day period in August, 1994. The results were validated using ground observations from the 111 station Oklahoma Mesonet. Validation of the remote sensing algorithms with Mesonet observations produced comparable results to previous validation studies. In addition, the validation process revealed inadequacies in thermal modeling that had not been detected in previous validation studies leading to the development of a new approach to estimate atmospheric water vapor.  相似文献   

Securing the Neoliberal City: Discourses of Creativity and Priority Neighborhoods in Toronto,Canada     

Deborah Leslie  Mia Hunt 《Urban geography》2013,34(8):1171-1192

This paper examines the convergence between the discourse of the creative city and the discourse on priority neighborhoods within urban policy imaginaries in Toronto, Canada. In particular, it examines the development of a number of arts programs targeted at low-income neighborhoods in the city. The twin objectives of these programs are to (a) foster creative and entrepreneurial subjectivities among “at-risk” youth, and (b) reduce the risk of violence that is presumed to be associated with youths living in poor neighborhoods. The paper analyzes how these two discourses are intertwined in a neoliberal politics devoted to enhancing regional quality-of-life competitiveness and to branding Toronto as an attractive creative-class destination. [Key words: creative city, poverty, low-income neighborhoods, neoliberalism, Toronto.]  相似文献   

GLACIAL GEOMORPHOLOGY OF THE WHITE MOUNTAINS,CALIFORNIA AND NEVADA: ESTABLISHMENT OF A GLACIAL CHRONOLOGY     

Deborah L. Elliott-Fisk 《自然地理学》2013,34(4):299-323

The White Mountains, astride the California-Nevada stateline, are the highest and westernmost of the Great Basin ranges. This range was extensively glaciated during the Quaternary Period. Glacial landforms and scattered erratics were identified in the field using primarily morpho-and lithostratigraphic criteria, and mapped on aerial photographs and topographic maps. Topographic characteristics of the glacial deposits were analyzed using standard statistical procedures. A sequence of glacial deposits was identified in terms of six glacial stages, these glaciations named according to type site, and relative ages inferred. With the exception of perched Stage I (early) deposits along the range crest, reconstructed equilibrium-line altitudes and elevation of the glacier termini increase to the present, with glacier length and inferred size decreasing through time. Preliminary data suggest that weathering and pedogenesis are also progressive, though environmental gradients mask some of these distinctions between deposits. It is hypothesized that the White Mountains have a similar glacial chronology to the adjacent Sierra Nevada, but that with the intensification of the Sierran rainshadow during the Quaternary, the extent of glaciation in the White Mountains apparently decreased through time owing to regional tectonic uplift. This had led to the preservation of a more complete sequence of glacial deposits than in the Sierra Nevada, making the delineation of multiple mid-Quaternary events possible in many valleys. Further radiometric and chronometric dating of these deposits is in progress. [Key words: Glaciation, Quaternary, glacial geomorphology, White Mountains, California, Nevada.  相似文献   

Evidence of microbially mediated arsenic mobilization from sediments of the Aquia aquifer, Maryland, USA     

Christine A. PearcyDarren A. Chevis  T. Jade HaugHolly A. Jeffries  Ningfang YangJianwu Tang  Deborah A. GrimmKaren H. Johannesson 《Applied Geochemistry》2011,26(4):575-586

Sediments from the Aquia aquifer in coastal Maryland were collected as part of a larger study of As in the Aquia groundwater flow system where As concentration are reported to reach levels as high as 1072 nmol kg⁻¹, (i.e., ∼80 μg/L). To test whether As release is microbially mediated by reductive dissolution of Fe(III) oxides/oxyhydroxides within the aquifer sediments, the Aquia aquifer sediment samples were employed in a series of microcosm experiments. The microcosm experiments consisted of sterilized serum bottles prepared with aquifer sediments and sterilized (i.e., autoclaved), artificial groundwater using four experimental conditions and one control condition. The four experimental conditions included the following scenarios: (1) aerobic; (2) anaerobic; (3) anaerobic + acetate; and (4) anaerobic + acetate + AQDS (anthraquinone-2,6-disulfonic acid). AQDS acts as an electron shuttle. The control condition contained sterilized aquifer sediments kept under anaerobic conditions with an addition of AQDS. Over the course of the 27 day microcosm experiments, dissolved As in the unamended (aerobic and anaerobic) microcosms remained constant at around ∼28 nmol kg⁻¹ (2 μg/L). With the addition of acetate, the amount of As released to the solution approximately doubled reaching ∼51 nmol kg⁻¹ (3.8 μg/L). For microcosm experiments amended with acetate and AQDS, the dissolved As concentrations exceeded 75 nmol kg⁻¹ (5.6 μg/L). The As concentrations in the acetate and acetate + AQDS amended microcosms are of similar orders of magnitude to As concentrations in groundwaters from the aquifer sediment sampling site (127-170 nmol kg⁻¹). Arsenic concentrations in the sterilized control experiments were generally less than 15 nmol kg⁻¹ (1.1 μg/L), which is interpreted to be the amount of As released from Aquia aquifer sediments owing to abiotic, surface exchange processes. Iron concentrations released to solution in each of the microcosm experiments were higher and more variable than the As concentrations, but generally exhibited similar trends to the As concentrations. Specifically, the acetate and acetate + AQDS amended microcosm typically exhibited the highest Fe concentrations (up to 1725 and 6566 nmol kg⁻¹, respectively). The increase in both As and Fe in the artificial groundwater solutions in these amended microcosm experiments strongly suggests that microbes within the Aquia aquifer sediments mobilize As from the sediment substrate to the groundwaters via Fe(III) reduction.  相似文献   

Spatial Patterns in Water Quality Associated with Submersed Plant Beds     

Renee K. Gruber  Deborah C. Hinkle  W. Michael Kemp 《Estuaries and Coasts》2011,34(5):961-972

This study describes the influence of submersed plant beds on spatial distributions of key water quality variables. An on-board flow-through water sampling system was used to investigate patterns in turbidity, chlorophyll-a, temperature, dissolved oxygen, and pH across a robust stand of the submersed plant Stuckenia pectinata. Spatially interpolated maps show that water quality conditions were significantly altered within this plant bed, especially during months of peak biomass, and that reduction of suspended particles focused at the bed’s edge. Comparison with a suite of submersed plant beds indicated that patterns were related to canopy height, shoot density, and cross-shore bed width. Wide and dense stands with tall canopies showed reduced turbidity and increased light penetration, while smaller sparser beds often showed elevated within-bed turbidity. These results suggest that bed effects on water quality conditions vary seasonally with plant canopy architecture and bed size, providing tentative guidelines for restoring self-sustaining beds.  相似文献   

Uranium and Thorium Concentration and Isotopic Composition in Five Glass (BHVO‐2G,BCR‐2G,NKT‐1G,T1‐G,ATHO‐G) and Two Powder (BHVO‐2, BCR‐2) Reference Materials     

Kathryn A. Matthews  Michael T. Murrell  Steven J. Goldstein  Andrew J. Nunn  Deborah E. Norman 《Geostandards and Geoanalytical Research》2011,35(2):227-234

Here we report uranium and thorium isotopic ratios and elemental concentrations measured in solid reference materials from the USGS (BHVO‐2G, BCR‐2G, NKT‐1G), as well as those from the MPI‐DING series (T1‐G, ATHO‐G). Specifically created for microanalysis, these naturally‐sourced glasses were fused from rock powders. They cover a range of compositions, elemental concentrations and expected isotopic ratios. The U‐Th isotopic ratios of two powdered source materials (BCR‐2, BHVO‐2) were also characterised. These new measurements via multi‐collector thermal ionisation mass spectrometry and multi‐collector inductively coupled plasma‐mass spectrometry can now be used to assess the relative performance of techniques and facilitate comparison of U‐Th data amongst laboratories in the geoscience community for in situ and bulk analyses.  相似文献   

North American terrestrial CO2 uptake largely offset by CH4 and N2O emissions: toward a full accounting of the greenhouse gas budget     

Hanqin Tian  Guangsheng Chen  Chaoqun Lu  Xiaofeng Xu  Daniel J. Hayes  Wei Ren  Shufen Pan  Deborah N. Huntzinger  Steven C. Wofsy 《Climatic change》2015,129(3-4):413-426

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Nonplanar Faults: Mechanics of Slip and Off-fault Damage     

James H. Dieterich  Deborah Elaine Smith 《Pure and Applied Geophysics》2009,166(10-11):1799-1815

Stress interactions and sliding characteristics of faults with random fractal waviness in a purely elastic medium differ both qualitatively and quantitatively from those of faults with planar surfaces. With nonplanar fault models, solutions for slip diverge as resolution of the fractal features increases, and the scaling of fault slip with fault rupture dimension becomes nonlinear. We show that the nonlinear scaling of slip and divergence of solutions arise because stresses from geometric interactions at irregularities along nonplanar faults grow with increasing slip and produce backstresses that progressively impede slip. However, in real materials with finite strength, yielding will halt the growth of the interaction stresses, which will profoundly affect slip of nonplanar faults. We infer that in the brittle seismogenic portion of the Earth’s crust, off-fault yielding occurs on pervasive secondary faults. Predicted rates of stress relaxation with distance from major faults with random fractal roughness follow a power-law relationship that is consistent with reported clustering of background seismicity up to 15 kilometers from faults.  相似文献   

Suzaku observation of NGC 3516: complex absorption and the broad and narrow Fe K lines     

A. Markowitz  J. N. Reeves  P. Serlemitsos  T. Yaqoob  H. Awaki  A. Fabian  L. Gallo  R. E. Griffiths  H. Kunieda  G. Miniutti  R. Mushotzky  T. Okajima 《Astronomische Nachrichten》2006,327(10):1087-1090

We present preliminary results from a 150 ks Suzaku observation of the Seyfert 1 galaxy NGC 3516. Suzaku 's wide bandpass has enabled us to deconvolve the broadband emitting and absorbing components in this object, breaking model degeneracies inherent in previous, smaller‐bandpass spectra. The primary power‐law continuum is absorbed by an ionized absorber as well as a partial‐covering absorber; the column density of the ionized absorber has increased by a factor of ∼3 since XMM‐Newton observations in 2001. We detect a soft power‐law component which may be scattered emission. We confirm the presence of the broad Fe line, finding a eV equivalent width line that indicates emission extending down to a few Schwarzschild radii. Models which exclude either the broad line or the partial‐covering absorber are rejected. Suzaku 's high effective area and low background near 6 keV also allow us to resolve the narrow Fe K emission line; we find a FWHM velocity width near 4000 km s^–1, commensurate with Broad Line Region velocities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献