Experiences of a “semantics smackdown”     

Adam M. Leadbetter  Adam Shepherd  Robert Arko  Cynthia Chandler  Yanning Chen  Nkemdirim Dockery  Renata Ferreira  Linyun Fu  Robert Thomas  Patrick West  Stephan Zednik 《Earth Science Informatics》2016,9(3):355-363

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A novel technique for detection of the toxic dinoflagellate, Karenia brevis, in the Gulf of Mexico from remotely sensed ocean color data     

Jennifer P. Cannizzaro  Kendall L. Carder  F. Robert Chen  Cynthia A. Heil  Gabriel A. Vargo 《Continental Shelf Research》2008

Karenia brevis, a toxic dinoflagellate that blooms regularly in the Gulf of Mexico, frequently causes widespread ecological and economic damage and can pose a serious threat to human health. A means for detecting blooms early and monitoring existing blooms that offers high spatial and temporal resolution is desired. Between 1999 and 2001, a large bio-optical data set consisting of spectral measurements of remote-sensing reflectance (R_rs(λ)), absorption (a(λ)), and backscattering (b_b(λ)) along with chlorophyll a concentrations and K. brevis cell counts was collected on the central west Florida shelf (WFS) as part of the Ecology and Oceanography of Harmful Algal Blooms (ECOHAB) and Hyperspectral Coastal Ocean Dynamics Experiment (HyCODE) programs. Reflectance model simulations indicate that absorption due to cellular pigmentation is not responsible for the factor of ∼3–4 decrease observed in R_rs(λ) for waters containing greater than 10⁴ cells l⁻¹ of K. brevis. Instead, particulate backscattering is responsible for this decreased reflectivity. Measured particulate backscattering coefficients were significantly lower when K. brevis concentrations exceeded 10⁴ cells l⁻¹ compared to values measured in high-chlorophyll (>1.5 mg m⁻³), diatom-dominated waters containing fewer than 10⁴ cells l⁻¹ of K. brevis. A classification technique for detecting high-chlorophyll, low-backscattering K. brevis blooms is developed. In addition, a method for quantifying chlorophyll concentrations in positively flagged pixels using fluorescence line height (FLH) data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) is introduced. Both techniques are successfully applied to Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and MODIS data acquired in late August 2001 and validated using in situ K. brevis cell concentrations.  相似文献   

The application of in situ permeable reactive (zero-valent iron) barrier technology for the remediation of chromate-contaminated groundwater: a field test   总被引：2，自引：0，他引：2  

Robert W. Puls  Cynthia J. Paul  Robert M. Powell 《Applied Geochemistry》1999,14(8):572

A small-scale field test was initiated in September 1994 to evaluate the in situ remediation of groundwater contaminated with chromate using a permeable reactive barrier composed of a mixture of zero-valent Fe, sand and aquifer sediment. The site used was an old chrome-plating facility located on a U.S. Coast Guard air base near Elizabeth City, North Carolina. Dissolved chromate concentrations were reduced to less than 0.01 mg/L via reduction from Cr(VI) to Cr(III) as a result of the corrosion of the Fe. As the Fe corrodes, pH increases, oxidation-reduction potential declines, dissolved oxygen is consumed, and Fe(II) is generated. Mineral phases formed as a result of the Fe corrosion include ferrous sulfides and various Fe oxides, hydroxides, and oxyhydroxides.  相似文献   

Temporal and spatial patterns of trace elements in the Patuxent River: A whole watershed approach   总被引：1，自引：0，他引：1  

Gerhardt F. Riedel  Sherry A. Williams  Georgia S. Riedel  Cynthia C. Gilmour  James G. Sanders 《Estuaries and Coasts》2000,23(4):521-535

Trace element distributions, partitioning, and speciation were examined at 15 sites in the Patuxent River watershed from May 1995 through October 1997 to determine possible sources of trace elements to the river and estuary, to examine the relationship of the trace element discharges to freshwater discharges as well as to land use and geographic region, to validate previous estimates of loadings to the river, and to provide baseline data for trace elements in the Patuxent River watershed and estuary. Six freshwater sites were examined, representing different basins and geographic provinces, and nine sites along the estuarine salinity gradient. Subregions within the watershed varied considerably in concentrations and areal yields for some elements. Concentrations of As, Cd, Ni, Pb, and Zn were elevated in the Coastal Plain sites compared to the Piedmont sites, while Cu and Hg were more evenly distributed. Cadmium, Cu, Hg, Ni, Pb, and Zn showed overall positive correlations with river flow while As and methylHg (meHg) showed negative correlations with river flow. Concentrations of trace elements in the estuarine portion of the river were generally low, and consistent with mixing between Patuxent River water with elevated concentrations and the lower concentrations of the Chesapeake Bay. Interesting features included a local Cd maximum in the low salinity region of the estuary, probably caused by desorption from suspended sediments, and a significant input of water containing high As concentrations from the Chesapeake Bay and from As being released from bottom sediments in summer. Comparisons between the estimated annual flux of trace elements and the estimates of suspected source terms (atmospheric deposition, urban runoff, and known point sources) suggest that, except for Hg, direct atmospheric deposition is small compared to fluvial loads. Current estimates of trace element inputs from point sources or from urban runoff are inadequate for comparison with other sources, because of inappropriate techniques and/or unacceptably high detection limits. A complete examination of trace element dynamics in the Patuxent River (and in other coastal systems) will require better data for these potential sources.  相似文献   

Naïve Simplicity: The Overlooked Piece of the Complexity‐Simplicity Paradigm          下载免费PDF全文

Franklin W. Schwartz  Ganming Liu  Pradeep Aggarwal  Cynthia M. Schwartz 《Ground water》2017,55(5):703-711

Concepts of simplicity and complexity in modeling have been explored in papers, editorials, and talks. The concept is not well understood because there are at least two flavors of simplicity. Modelers envision simplicity (i.e., elegant simplicity) as the sought‐after goal in modeling, but naïve simplicity, which is the focus of this paper, is commonly unrecognized and dangerous. The problem is that naïve or simple ideas are often mistaken for settled science and come with the prospect of being more wrong than right. The concept of the so‐called simplicity cycle, in relation to classical problems of carbon‐14 age and salinity in closed‐basin lakes, is used to illustrate these points. The emerging problems of water‐mosquitoes‐diseases show the value of mapping new problems to the simplicity cycle. Researchers can “know what they do not know” and avoid the dangers of naïve simplicity.  相似文献   

An interdisciplinary approach to HIV/AIDS stigma and discrimination in Belize: the roles of geography and ethnicity     

Cynthia K. Pope  Gerald Shoultz 《GeoJournal》2012,77(4):489-503

Belize experiences the highest rates of HIV/AIDS in Central America, ranging between 2.1 and 3.2% (World Health Organization 2008). To add to the limited literature on HIV/AIDS Stigma and Discrimination (HASD) in Belize, the authors conducted a study to assess whether stigma and discrimination is related to geography and ethnicity. One-hundred forty participants were interviewed using a structured survey instrument at three different parts of the country, and the results were analyzed quantitatively. These places were Cayo District on the western border with Guatemala, Belize City, and two cayes (Caye Caulker and Ambergris Caye). Respondents in Belize City generally held the lowest rates of stigmatizing and discriminatory attitudes towards individuals living with HIV/AIDS, highlighting a possible relationship between geography and ethnicity. Concurrently, self-identifying Afro-Belizeans and Creoles reported lower rates of HASD attitudes in some contexts than other ethnic groups. The results show that there may a relation between geography, ethnicity, and HASD, and that a randomized, controlled study is an important next step in determining the strength of that relation.  相似文献   

Understanding the evolution of a disaster��a Framework for Assessing Crisis in a System Environment (FACSE)     

Cynthia Chen  Dave Neal  Mengchu Zhou 《Natural Hazards》2013,65(1):407-422

To understand the evolution of a disaster, we propose a Framework for Assessing Crisis in a System Environment (FACSE). FACSE is set in a multi-system environment, containing the human system as well as the various natural and technological systems that interact with people. We take a lifecycle perspective, via which we quantify rhythms of life exhibited in multiple systems, across different scales, at different times. The lifecycle perspective also implies a relative approach in that rhythms of life during time t can be compared against those during t-1. We illustrate how rhythms of life in the human system can be measured at different scales. We propose a new concept??the degree of disaster, which is a composite score that encompasses the various measurements of rhythms of life from multiple systems, across different scales. We conclude the paper by discussing the potential offered by FACSE in disaster research as well as the limitations.  相似文献   

Earth observations during space shuttle flight STS‐31: The earth from 600 km     

Cynthia A. Evans  Mark A. Chambers  Michael R. Helfert  Kamlesh P. Lulla  Charles A. Wood  Loren J. Shriver 《国际地球制图》2013,28(3):99-111

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Earth observations during space shuttle flight STS‐46: Atlantis ’ mission to planet earth (July 31‐August 8, 1992)     

Kamlesh Lulla  David Amsbury  M. Justin Wilkinson  Cynthia Evans  Steve Ackleson  Loren J. Shriver Commander 《国际地球制图》2013,28(3):67-80

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Using social media data to understand and assess disasters   总被引：4，自引：1，他引：3  

Xiangyang Guan  Cynthia Chen 《Natural Hazards》2014,74(2):837-850

This paper contributes to the understanding of disasters from the perspective of social media activities. We develop a measure based on Twitter activities that can be used to quantify the evolution of disasters and thus demonstrate temporal–spatial patterns of Twitter activities particularly near the coastline and in large urban areas during Hurricane Sandy. We also show a close relationship between hurricane damages and Twitter activities. Our findings suggest the potential of using social media activities for rapid damage assessment.  相似文献