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  1. Article: Attributing health effects to apportioned components and sources of particulate matter: An evaluation of collective results

    Stanek, Lindsay Wichers / Sacks, Jason D / Dutton, Steven J / Dubois, Jean-Jacques B

    Atmospheric environment. 2011 Oct., v. 45, no. 32

    2011  

    Abstract: It has been hypothesized that the composition of particulate matter (PM) may be a better predictor of health effects than PM mass alone. The regional differences in PM composition and the heterogeneity in PM risk estimates in large multi-city ... ...

    Abstract It has been hypothesized that the composition of particulate matter (PM) may be a better predictor of health effects than PM mass alone. The regional differences in PM composition and the heterogeneity in PM risk estimates in large multi-city epidemiologic studies are consistent with this hypothesis. Since 2005, efforts have been made to relate apportioned components and sources of PM with human health outcomes in epidemiology, controlled human exposure and toxicology studies. We reviewed published studies that: 1) focused on short-term exposure to PM; 2) included at least five components of PM; 3) grouped them into factors or sources; and 4) used quantitative methods to examine the relationship between the factors or sources and health effects. We then examined whether specific groups of PM components or sources of PM are consistently linked to specific health effects across studies. Collectively, these studies suggest that cardiovascular effects may be associated with PM₂.₅ from crustal or combustion sources, including traffic, but at this time, no consistent relationships have emerged. Fewer studies evaluated respiratory health effects, and the evidence for associations was limited. Apportionment methods have linked a variety of health effects to multiple groups of PM components and sources of PM, but the collective evidence has not yet isolated factors or sources that would be closely and unequivocally related to specific health outcomes.
    Keywords atmospheric chemistry ; combustion ; epidemiological studies ; human health ; humans ; particulates ; quantitative analysis ; risk estimate ; toxicology ; traffic
    Language English
    Dates of publication 2011-10
    Size p. 5655-5663.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 216368-8
    ISSN 0004-6981 ; 1352-2310
    ISSN 0004-6981 ; 1352-2310
    DOI 10.1016/j.atmosenv.2011.07.023
    Database NAL-Catalogue (AGRICOLA)

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  2. Article: Optimizing the statistical estimation of the parameters of the Farquhar-von Caemmerer-Berry model of photosynthesis.

    Dubois, Jean-Jacques B / Fiscus, Edwin L / Booker, Fitzgerald L / Flowers, Michael D / Reid, Chantal D

    The New phytologist

    2007  Volume 176, Issue 2, Page(s) 402–414

    Abstract: The model of Farquhar, von Caemmerer and Berry is the standard in relating photosynthetic carbon assimilation and concentration of intercellular CO(2). The techniques used in collecting the data from which its parameters are estimated have been the ... ...

    Abstract The model of Farquhar, von Caemmerer and Berry is the standard in relating photosynthetic carbon assimilation and concentration of intercellular CO(2). The techniques used in collecting the data from which its parameters are estimated have been the object of extensive optimization, but the statistical aspects of estimation have not received the same attention. The model segments assimilation into three regions, each modeled by a distinct function. Three parameters of the model, namely the maximum rate of Rubisco carboxylation (V(c max)), the rate of electron transport (J), and nonphotorespiratory CO(2) evolution (R(d)), are customarily estimated from gas exchange data through separate fitting of the component functions corresponding to the first two segments. This disjunct approach is problematic in requiring preliminary arbitrary subsetting of data into sets believed to correspond to each region. It is shown how multiple segments can be estimated simultaneously, using the entire data set, without predetermination of transitions by the investigator. Investigation of the number of parameters that can be estimated in the two-segment model suggests that, under some conditions, it is possible to estimate four or even five parameters, but that only V(c max), J, and R(d), have good statistical properties. Practical difficulties and their solutions are reviewed, and software programs are provided.
    MeSH term(s) Carbon Dioxide/metabolism ; Models, Biological ; Nonlinear Dynamics ; Photosynthesis ; Plants/metabolism ; Ribulose-Bisphosphate Carboxylase/metabolism
    Chemical Substances Carbon Dioxide (142M471B3J) ; Ribulose-Bisphosphate Carboxylase (EC 4.1.1.39)
    Language English
    Publishing date 2007-09-11
    Publishing country England
    Document type Journal Article
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2007.02182.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Optimizing the statistical estimation of the parameters of the Farquhar-von Caemmerer-Berry model of photosynthesis

    Dubois, Jean-Jacques B / Fiscus, Edwin L / Booker, Fitzgerald L / Flowers, Michael D / Reid, Chantal D

    New phytologist. 2007 Oct., v. 176, no. 2

    2007  

    Abstract: The model of Farquhar, von Caemmerer and Berry is the standard in relating photosynthetic carbon assimilation and concentration of intercellular CO₂. The techniques used in collecting the data from which its parameters are estimated have been the object ... ...

    Abstract The model of Farquhar, von Caemmerer and Berry is the standard in relating photosynthetic carbon assimilation and concentration of intercellular CO₂. The techniques used in collecting the data from which its parameters are estimated have been the object of extensive optimization, but the statistical aspects of estimation have not received the same attention. The model segments assimilation into three regions, each modeled by a distinct function. Three parameters of the model, namely the maximum rate of Rubisco carboxylation (Vc max), the rate of electron transport (J), and nonphotorespiratory CO₂ evolution (Rd), are customarily estimated from gas exchange data through separate fitting of the component functions corresponding to the first two segments. This disjunct approach is problematic in requiring preliminary arbitrary subsetting of data into sets believed to correspond to each region. It is shown how multiple segments can be estimated simultaneously, using the entire data set, without predetermination of transitions by the investigator. Investigation of the number of parameters that can be estimated in the two-segment model suggests that, under some conditions, it is possible to estimate four or even five parameters, but that only Vc max, J, and Rd, have good statistical properties. Practical difficulties and their solutions are reviewed, and software programs are provided.
    Keywords assimilation (physiology) ; photosynthesis ; ribulose-bisphosphate carboxylase ; carboxylation ; electron transport chain ; mathematical models ; nonlinear models ; regression analysis
    Language English
    Dates of publication 2007-10
    Size p. 402-414.
    Publisher Blackwell Publishing Ltd
    Publishing place Oxford, UK
    Document type Article
    ZDB-ID 208885-x
    ISSN 1469-8137 ; 0028-646X
    ISSN (online) 1469-8137
    ISSN 0028-646X
    DOI 10.1111/j.1469-8137.2007.02182.x
    Database NAL-Catalogue (AGRICOLA)

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    In stock of ZB MED Bonn / Germany

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  4. Article: Carbon Dioxide Enhancement Effects in Container- versus Ground-Grown Soybean at Equal Planting Densities

    Fiscus, Edwin L / Booker, Fitzgerald L / Dubois, Jean-Jacques B / Rufty, Thomas W / Burton, Joseph W / Pursley, Walter A

    Crop science. 2007 Nov., v. 47, no. 6

    2007  

    Abstract: Prior work showed that CO enhancement ratios (ER) were similar for plants grown in open-top chambers (OTCs) whether grown in the ground or in insulated containers aboveground. Per plant comparisons were suspect since the ground-grown plants were ... ...

    Abstract Prior work showed that CO enhancement ratios (ER) were similar for plants grown in open-top chambers (OTCs) whether grown in the ground or in insulated containers aboveground. Per plant comparisons were suspect since the ground-grown plants were cultivated in rows at normal densities making it difficult to separate the effects of plant competition from the variables of interest. Soybean [ (L.) Merr. cv. Essex] was grown in the ground and in aboveground containers in OTCs in ambient and elevated CO at equal planting densities. The hypothesis was that at equal densities, container- and ground-grown plants would exhibit both equivalent ERs and equivalent per plant yields. Although the only differences in net photosynthetic rate (A:μmol m s) and conductance to water vapor (g:mol m s) were due to CO and container- and ground-grown plants had similar ERs (mean = 20%), per plant yields were still less in the container-grown plants at both levels of CO (mean = −17%). Reproductive measures, except mass per seed, as well as total stem biomass were significantly reduced in the containers. High CO increased seed oil concentration and the level of fatty acid saturation. The only observed environmental difference was higher daytime root zone temperatures in containers (2–6°C). The robust ERs suggest that neither above- nor below-ground resource limitations was the cause of the yield discrepancies.
    Keywords Glycine max ; soybeans ; carbon dioxide ; elevated atmospheric gases ; plant growth ; container-grown plants ; plant density ; environmental factors ; plant competition ; photosynthesis ; water vapor ; leaf conductance ; crop yield ; plant reproduction ; lipid content ; saturated fatty acids ; root zone temperature ; North Carolina
    Language English
    Dates of publication 2007-11
    Size p. 2486-2494.
    Publishing place Crop Science Society of America
    Document type Article
    Note epub
    ZDB-ID 2785315-9
    ISSN 1435-0653
    ISSN 1435-0653
    DOI 10.2135/cropsci2006.12.0755
    Database NAL-Catalogue (AGRICOLA)

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  5. Article: Attributing health effects to apportioned components and sources of particulate matter: An evaluation of collective results

    Stanek, Lindsay Wichers / Sacks, Jason D. / Dutton, Steven J. / Dubois, Jean-Jacques B.

    Atmospheric environment

    Volume v. 45,, Issue no. 3

    Abstract: It has been hypothesized that the composition of particulate matter (PM) may be a better predictor of health effects than PM mass alone. The regional differences in PM composition and the heterogeneity in PM risk estimates in large multi-city ... ...

    Abstract It has been hypothesized that the composition of particulate matter (PM) may be a better predictor of health effects than PM mass alone. The regional differences in PM composition and the heterogeneity in PM risk estimates in large multi-city epidemiologic studies are consistent with this hypothesis. Since 2005, efforts have been made to relate apportioned components and sources of PM with human health outcomes in epidemiology, controlled human exposure and toxicology studies. We reviewed published studies that: 1) focused on short-term exposure to PM; 2) included at least five components of PM; 3) grouped them into factors or sources; and 4) used quantitative methods to examine the relationship between the factors or sources and health effects. We then examined whether specific groups of PM components or sources of PM are consistently linked to specific health effects across studies. Collectively, these studies suggest that cardiovascular effects may be associated with PM₂.₅ from crustal or combustion sources, including traffic, but at this time, no consistent relationships have emerged. Fewer studies evaluated respiratory health effects, and the evidence for associations was limited. Apportionment methods have linked a variety of health effects to multiple groups of PM components and sources of PM, but the collective evidence has not yet isolated factors or sources that would be closely and unequivocally related to specific health outcomes.
    Keywords human health ; traffic ; risk estimate ; quantitative analysis ; toxicology ; humans ; atmospheric chemistry ; epidemiological studies ; combustion ; particulates
    Language English
    Document type Article
    ISSN 1352-2310
    Database AGRIS - International Information System for the Agricultural Sciences and Technology

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