Uncertainties in the geographic context of health behaviors: a study of substance users’ exposure to psychosocial stress using GPS data     

Mei-Po Kwan  Jue Wang  Matthew Tyburski  David H. Epstein  William J. Kowalczyk  Kenzie L. Preston 《International journal of geographical information science》2019,33(6):1176-1195

ABSTRACT

This study examined how contextual areas defined and operationalized differently may lead to different exposure estimates. Substance users’ exposures to environmental stress (in terms of two variables: community social economic status and crime) were assessed from global positioning systems (GPS) data. Participants were 47 outpatients with substance use disorders admitted for methadone maintenance at a research clinic in Baltimore, Maryland. From 35.2 million GPS tracking points, we compared 7 different methods for defining activity space. The different methods yielded different exposure estimates, which would lead to different conclusions in studies using only one method. These results have important implications for future research on the effect of contextual influences on health behaviors and outcomes: whether a study observes any significant influence of an environmental factor on health may depend on what contextual units are used to assess individual exposure.  相似文献   

A rigorous probabilistic seismic hazard model for Southeast China: a case study of Hong Kong     

J. W. Pappin  R. C. H. Koo  H. Jiang  J. S. H. Kwan  Y. B. Yu  M. M. L. So  Y. K. Shiu  K. K. S. Ho  W. K. Pun 《Bulletin of Earthquake Engineering》2015,13(12):3597-3623

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A Benthic Terrain Classification Scheme for American Samoa     

Emily R. Lundblad  Dawn J. Wright  Joyce Miller  Emily M. Larkin  Ronald Rinehart  David F. Naar 《Marine Geodesy》2013,36(2):89-111

Coral reef ecosystems, the most varied on earth, continually face destruction from anthropogenic and natural threats. The U.S. Coral Reef Task Force seeks to characterize and map priority coral reef ecosystems in the U.S./Trust Territories by 2009. Building upon NOAA Biogeography shallow-water classifications based on Ikonos imagery, presented here are new methods, based on acoustic data, for classifying benthic terrain below 30 m, around Tutuila, American Samoa. The result is a new classification scheme for American Samoa that extends and improves the NOAA Biogeography scheme, which, although developed for Pacific island nations and territories, is only applicable to a maximum depth of 30 m, due to the limitations of satellite imagery. The scheme may be suitable for developing habitat maps pinpointing high biodiversity around coral reefs throughout the western Pacific.  相似文献   

Using GIS and perceived distance to understand the unequal geographies of healthcare in lower-income urban neighbourhoods   总被引：2，自引：0，他引：2  

Hawthorne TL  Kwan MP 《The Geographical journal》2012,178(1):18-30

Geographers play important roles in public health research, particularly in understanding healthcare accessibility, utilisation, and individual healthcare experiences. Most accessibility studies have benefited from the increased sophistication of geographic information systems (GIS). Some studies have been enhanced with semi-structured in-depth interviews to understand individual experiences of people as they access healthcare. However, few accessibility studies have explicitly utilised individual in-depth interview data in the construction of new GIS accessibility measures. Using mixed methods including GIS analysis and individual data from semi-structured in-depth interviews, we offer satisfaction-adjusted distance as a new way of conceptualising accessibility in GIS. Based on fieldwork in a predominantly lower-income community in Columbus, Ohio (USA), we find many residents felt neighbourhood healthcare facilities offered low-quality care, which suggested an added perceived distance as they attempt to access high-quality healthcare facilities. The satisfaction-adjusted distance measure accounts for the perceived distance some residents feel as they search for high-quality healthcare in lower-income urban neighbourhoods. In moving beyond conventional GIS and re-conceptualising accessibility in this way, we offer a more realistic portrayal of the issues lower-income urban residents face as they attempt to access high-quality healthcare facilities. The work has theoretical implications for conceptualising healthcare accessibility, advances the mixed-methodologies literature, and argues for a more equitable distribution of high-quality healthcare in urban neighbourhoods.  相似文献   

Use of plants in the European Palaeolithic: A review of the evidence     

Joyce A. Tyldesley  Paul G. Bahn 《Quaternary Science Reviews》1983,2(1):53-81

The varied evidence available for the different uses to which plant materials were put during the European Palaeolithic is summarised. Actual remains of plants are more abundant than is generally realised, while the indirect clues provided by tools, human teeth and artistic depictions help to fill out the picture.  相似文献   

Rare earth and trace element geochemistry of a fragment of jurassic seafloor,Point Sal,California     

Martin Menzies  Douglas Blanchard  Joyce Brannon  Randy Korotev 《Geochimica et cosmochimica acta》1977,41(10):1419-1430

A suite of rocks from the Point Sal ophiolite, California, were analyzed for rare earth elements (REE), Sc, Co, Na₂O, Cr, Zn and FeO. The lavas all have either flat or slightly light REE (LREE) depleted profiles relative to chondrites. The lavas contain smectite or greenschist facies mineralogy and some have radiogenically enriched ${}^{87}\text{Sr}{}^{86}\text{Sr}$ ratios. This is interpreted as evidence of basaltseawater interaction (Hopsonet al., 1975; Davis and Lass, 1975). The smectite and zeolite bearing lavas that have been exposed to seawater for prolonged periods have anomalous Ce abundances. At higher grades of metamorphism, the lavas show no marked changes in light REE. The plutonic igneous rocks vary from early cumulus dunite to late stage, noncumulus diorite. All the plutonic rocks are light REE depleted with total REE abundance varying by a factor of 100 × between the dunites and diorites. Analyses of clinopyroxene and hornblende separates indicate that these two minerals strongly influence the REE characteristics of the early cumulates and late stage fractionates, respectively.In general, REE contents are: hornblende > clinopyroxene > plagioclase > orthopyroxene > olivine. Estimates of the REE compositions of parental lavas were obtained by calculating the REE contents of liquids in equilibrium with early cumulate clinopyroxenes. This reveals that the parent to the stratiform sequence was more depleted in light REE than the parent to the lava pile.  相似文献   

Major,minor, and trace element compositions of peridotitic and basaltic komatiites from the precambrian crust of Southern Africa     

A. Günter Herrmann  Douglas P. Blanchard  Larry A. Haskin  Jeffrey W. Jacobs  Doris Knake  Randy L. Korotev  Joyce C. Brannon 《Contributions to Mineralogy and Petrology》1976,59(1):1-12

Major and trace element compositional data are reported for nine mafic and ultramafic rock samples from the Barberton greenstone belt. Rocks from this province are among the oldest fragments of the Earth's crust (3.5 b.y.). The data are consistent with an oceanic crust related origin for these rocks. The high abundances of Ni in these samples make their origin by fractional crystallization of a primitive magma unlikely but are consistent with their generation by partial melting of an upper mantle source. The basaltic samples from the Komati formation can be related by small degrees of partial melting of a primitive upper mantle source to the peridotitic komatiite which probably derived from much more extensive partial melting of a similar source. REE and especially Ni abundances limit the proportion of olivine that is permitted in the residue.  相似文献   

TBT toxicity on the marine microalga Nannochloropsis oculata   总被引：1，自引：0，他引：1  

Sidharthan M  Young KS  Woul LH  Soon PK  Shin HW 《Marine pollution bulletin》2002,45(1-12):177-180

Commercial antifouling formulations containing TBT are the major source of organotin contamination in coastal waters. In view of the persisting TBT residues (13 ng Sn l⁻¹) in the coastal waters of South Korea, an attempt has been made to evaluate the growth response and biochemical composition of laboratory-cultured Nannochloropsis oculata to TBT toxicity. It is evident that the persisting concentration level of TBT is high enough to cause adverse effect on the microalgal species. The EC₅₀ (24 h) was found to be at 0.89 nM level of TBT for this marine eustigmatophyte N. oculata. Photosynthetic pigment content was significantly affected. At elevated TBT concentrations of 1.0 nM, especially pronounced changes in biochemical composition was found. TBT tolerance of N. oculata and its growth as well as biochemical responses are discussed.  相似文献   

Productivity response of climax temperate forests to elevated temperature and carbon dioxide: a north american comparison between two global models     

A. D. McGuire  L. A. Joyce  D. W. Kicklighter  J. M. Melillo  G. Esser  C. J. Vorosmarty 《Climatic change》1993,24(4):287-310

We assess the appropriateness of using regression- and process-based approaches for predicting biogeochemical responses of ecosystems to global change. We applied a regression-based model, the Osnabruck Model (OBM), and a process-based model, the Terrestrial Ecosystem Model (TEM), to the historical range of temperate forests in North America in a factorial experiment with three levels of temperature (+0 °C, +2 °C, and +5 °C) and two levels of CO₂ (350 ppmv and 700 ppmv) at a spatial resolution of 0.5° latitude by 0.5° longitude. For contemporary climate (+0 °C, 350 ppmv), OBM and TEM estimate the total net primary productivity (NPP) for temperate forests in North America to be 2.250 and 2.602 × 10¹⁵ g C ? yr^?1, respectively. Although the continental predictions for contemporary climate are similar, the responses of NPP to altered climates qualitatively differ; at +0 °C and 700 ppmv CO₂, OBM and TEM predict median increases in NPP of 12.5% and 2.5%, respectively. The response of NPP to elevated temperature agrees most between the models in northern areas of moist temperate forest, but disagrees in southern areas and in regions of dry temperate forest. In all regions, the response to CO₂ is qualitatively different between the models. These differences occur, in part, because TEM includes known feedbacks between temperature and ecosystem processes that affect N availability, photosynthesis, respiration, and soil moisture. Also, it may not be appropriate to extrapolate regression-based models for climatic conditions that are not now experienced by ecosystems. The results of this study suggest that the process-based approach is able to progress beyond the limitations of the regression-based approach for predicting biogeochemical responses to global change.  相似文献   

Spatiotemporal modelling of rainfall-induced landslides using machine learning     

Ng  C. W. W.  Yang  B.  Liu  Z. Q.  Kwan  J. S. H.  Chen  L. 《Landslides》2021,18(7):2499-2514

Landslides - Natural terrain landslides are mainly triggered by rainstorms in Hong Kong, which pose great threats to life and property. To mitigate landslide risk, building a prediction model which...  相似文献