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Klaus Wallmann - One of the best experts on this subject based on the ideXlab platform.
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A new look at the multi-G Model for orGanic carbon deGradation in surface marine sediments for coupled benthic-pelaGic simulations of the Global ocean
Biogeosciences, 2018Co-Authors: Konstantin Stolpovsky, Andrew W. Dale, Klaus WallmannAbstract:Abstract. The kinetics of particulate orGanic carbon (POC) mineralization in marine surface sediments is not well constrained. This creates considerable uncertainties when benthic processes are considered in Global bioGeochemical or Earth system circulation Models to simulate climate–ocean interactions and bioGeochemical tracer distributions in the ocean. In an attempt to improve our understandinG of the rate and depth distribution of orGanic carbon mineralization in bioturbated (0–20 cm) sediments at the Global scale, we parameterized a 1-D diaGenetic Model that simulates the mineralization of three discrete POC pools (a multi-G Model). The rate constants of the three reactive classes (hiGhly reactive, reactive, refractory) are fixed and determined to be 70, 0.5 and ∼ 0.001 yr−1, respectively, based on the Martin curve Model for pelaGic POC deGradation. In contrast to previous approaches, however, the reactivity of the orGanic material deGraded in the seafloor is continuous with, and set by, the apparent reactivity of material sinkinG throuGh the water column. Despite the simplifications of describinG POC remineralization usinG G-type approaches, the Model is able to simulate a Global database (185 stations) of benthic oxyGen and nitrate fluxes across the sediment–water interface in addition to porewater oxyGen and nitrate distributions and orGanic carbon burial efficiencies. It is further consistent with deGradation experiments usinG fresh phytoplankton reported in a previous study. We propose that an important yet mostly overlooked consideration in upscalinG approaches is the proportion of the reactive POC classes reachinG the seafloor in addition to their reactivity. The approach presented is applicable to both steady-state and non-steady state scenarios, and links POC deGradation kinetics in sedimentary environments to water depth and the POC rain rate to the seafloor.
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A new look at the multi-G Model for orGanic carbon deGradation in surface marine sediments for coupled benthic-pelaGic simulations of the Global ocean
2017Co-Authors: Konstantin Stolpovsky, Andrew W. Dale, Klaus WallmannAbstract:Abstract. The kinetics of particulate orGanic carbon (POC) mineralization in marine surface sediments is not well constrained. This creates considerable uncertainties when benthic processes are considered in Global bioGeochemical or Earth system circulation Models to simulate climate-ocean interactions and bioGeochemical tracers in the ocean. In an attempt to improve our understandinG of the rate and depth distribution of orGanic carbon mineralization in bioturbated (0–10 cm) sediments, we parameterized a 1-D diaGenetic Model that simulates the reactivity of three discrete POC pools at Global scale (a multi-G Model). The rate constants of the three reactive classes (hiGhly reactive, reactive, refractory) are fixed and determined to be 70 yr−1, 0.5 yr−1, and ~0.001 yr−1, respectively, based on the Martin curve Model for pelaGic POC deGradation. In contrast to previous approaches, the reactivity of the orGanic material deGraded in the seafloor is continuous with, and set by, the apparent reactivity of material sinkinG throuGh the water column. The Model is able to simulate a Global database (185 stations) of benthic oxyGen and nitrate fluxes across the sediment-water interface in addition to porewater oxyGen and nitrate distributions and orGanic carbon burial efficiencies. It is further consistent with deGradation experiments of fresh phytoplankton. We propose that an important yet mostly overlooked consideration in previous upscalinG approaches is the proportion of the relative reactive POC classes reachinG the seafloor in addition to their reactivity. The approach presented is applicable to both steady-state and non-steady state scenarios, and links POC deGradation kinetics in sedimentary environments to water depth and the POC rain rate to the seafloor.
Hossein Nadeb - One of the best experts on this subject based on the ideXlab platform.
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Stochastic Comparisons between the Extreme Claim Amounts from Two HeteroGeneous Portfolios in the Case of Transmuted-G Model
North American Actuarial Journal, 2020Co-Authors: Hossein Nadeb, Hamzeh Torabi, Ali DolatiAbstract:Let Xλ1,…,Xλn be independent and non-neGative random variables belonG to the transmuted-G Model and let Yi=IpiXλi,i=1,…,n, where Ip1,…,Ipn are independent Bernoulli random variables independent of ...
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Preservation properties of stochastic orders by transformation to the transmuted-G Model
Communications in Statistics - Theory and Methods, 2019Co-Authors: Hossein Nadeb, Hamzeh TorabiAbstract:The transmuted-G Model is a useful technique to construct some new distributions by addinG a parameter. This paper considers stochastic comparisons in the transmuted-G family with different paramet...
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Stochastic comparisons between the extreme claim amounts from two heteroGeneous portfolios in the case of transmuted-G Model
arXiv: Applications, 2018Co-Authors: Hossein Nadeb, Hamzeh Torabi, Ali DolatiAbstract:Let $X_{\lambda_1}, \ldots , X_{\lambda_n}$ be independent non-neGative random variables belonG to the transmuted-G Model and let $Y_i=I_{p_i} X_{\lambda_i}$, $i=1,\ldots,n$, where $I_{p_1}, \ldots, I_{p_n}$ are independent Bernoulli random variables independent of $X_{\lambda_i}$'s, with ${\rm E}[I_{p_i}]=p_i$, $i=1,\ldots,n$. In actuarial sciences, $Y_i$ corresponds to the claim amount in a portfolio of risks. In this paper we compare the smallest and the larGest claim amounts of two sets of independent portfolios belonGinG to the transmuted-G Model, in the sense of usual stochastic order, hazard rate order and dispersive order, when the variables in one set have the parameters $\lambda_1,\ldots,\lambda_n$ and the variables in the other set have the parameters $\lambda^{*}_1,\ldots,\lambda^{*}_n$. For illustration we apply the results to the transmuted-G exponential and the transmuted-G Weibull Models.
Hamzeh Torabi - One of the best experts on this subject based on the ideXlab platform.
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Stochastic Comparisons between the Extreme Claim Amounts from Two HeteroGeneous Portfolios in the Case of Transmuted-G Model
North American Actuarial Journal, 2020Co-Authors: Hossein Nadeb, Hamzeh Torabi, Ali DolatiAbstract:Let Xλ1,…,Xλn be independent and non-neGative random variables belonG to the transmuted-G Model and let Yi=IpiXλi,i=1,…,n, where Ip1,…,Ipn are independent Bernoulli random variables independent of ...
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Preservation properties of stochastic orders by transformation to the transmuted-G Model
Communications in Statistics - Theory and Methods, 2019Co-Authors: Hossein Nadeb, Hamzeh TorabiAbstract:The transmuted-G Model is a useful technique to construct some new distributions by addinG a parameter. This paper considers stochastic comparisons in the transmuted-G family with different paramet...
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Stochastic comparisons between the extreme claim amounts from two heteroGeneous portfolios in the case of transmuted-G Model
arXiv: Applications, 2018Co-Authors: Hossein Nadeb, Hamzeh Torabi, Ali DolatiAbstract:Let $X_{\lambda_1}, \ldots , X_{\lambda_n}$ be independent non-neGative random variables belonG to the transmuted-G Model and let $Y_i=I_{p_i} X_{\lambda_i}$, $i=1,\ldots,n$, where $I_{p_1}, \ldots, I_{p_n}$ are independent Bernoulli random variables independent of $X_{\lambda_i}$'s, with ${\rm E}[I_{p_i}]=p_i$, $i=1,\ldots,n$. In actuarial sciences, $Y_i$ corresponds to the claim amount in a portfolio of risks. In this paper we compare the smallest and the larGest claim amounts of two sets of independent portfolios belonGinG to the transmuted-G Model, in the sense of usual stochastic order, hazard rate order and dispersive order, when the variables in one set have the parameters $\lambda_1,\ldots,\lambda_n$ and the variables in the other set have the parameters $\lambda^{*}_1,\ldots,\lambda^{*}_n$. For illustration we apply the results to the transmuted-G exponential and the transmuted-G Weibull Models.
Konstantin Stolpovsky - One of the best experts on this subject based on the ideXlab platform.
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A new look at the multi-G Model for orGanic carbon deGradation in surface marine sediments for coupled benthic-pelaGic simulations of the Global ocean
Biogeosciences, 2018Co-Authors: Konstantin Stolpovsky, Andrew W. Dale, Klaus WallmannAbstract:Abstract. The kinetics of particulate orGanic carbon (POC) mineralization in marine surface sediments is not well constrained. This creates considerable uncertainties when benthic processes are considered in Global bioGeochemical or Earth system circulation Models to simulate climate–ocean interactions and bioGeochemical tracer distributions in the ocean. In an attempt to improve our understandinG of the rate and depth distribution of orGanic carbon mineralization in bioturbated (0–20 cm) sediments at the Global scale, we parameterized a 1-D diaGenetic Model that simulates the mineralization of three discrete POC pools (a multi-G Model). The rate constants of the three reactive classes (hiGhly reactive, reactive, refractory) are fixed and determined to be 70, 0.5 and ∼ 0.001 yr−1, respectively, based on the Martin curve Model for pelaGic POC deGradation. In contrast to previous approaches, however, the reactivity of the orGanic material deGraded in the seafloor is continuous with, and set by, the apparent reactivity of material sinkinG throuGh the water column. Despite the simplifications of describinG POC remineralization usinG G-type approaches, the Model is able to simulate a Global database (185 stations) of benthic oxyGen and nitrate fluxes across the sediment–water interface in addition to porewater oxyGen and nitrate distributions and orGanic carbon burial efficiencies. It is further consistent with deGradation experiments usinG fresh phytoplankton reported in a previous study. We propose that an important yet mostly overlooked consideration in upscalinG approaches is the proportion of the reactive POC classes reachinG the seafloor in addition to their reactivity. The approach presented is applicable to both steady-state and non-steady state scenarios, and links POC deGradation kinetics in sedimentary environments to water depth and the POC rain rate to the seafloor.
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A new look at the multi-G Model for orGanic carbon deGradation in surface marine sediments for coupled benthic-pelaGic simulations of the Global ocean
2017Co-Authors: Konstantin Stolpovsky, Andrew W. Dale, Klaus WallmannAbstract:Abstract. The kinetics of particulate orGanic carbon (POC) mineralization in marine surface sediments is not well constrained. This creates considerable uncertainties when benthic processes are considered in Global bioGeochemical or Earth system circulation Models to simulate climate-ocean interactions and bioGeochemical tracers in the ocean. In an attempt to improve our understandinG of the rate and depth distribution of orGanic carbon mineralization in bioturbated (0–10 cm) sediments, we parameterized a 1-D diaGenetic Model that simulates the reactivity of three discrete POC pools at Global scale (a multi-G Model). The rate constants of the three reactive classes (hiGhly reactive, reactive, refractory) are fixed and determined to be 70 yr−1, 0.5 yr−1, and ~0.001 yr−1, respectively, based on the Martin curve Model for pelaGic POC deGradation. In contrast to previous approaches, the reactivity of the orGanic material deGraded in the seafloor is continuous with, and set by, the apparent reactivity of material sinkinG throuGh the water column. The Model is able to simulate a Global database (185 stations) of benthic oxyGen and nitrate fluxes across the sediment-water interface in addition to porewater oxyGen and nitrate distributions and orGanic carbon burial efficiencies. It is further consistent with deGradation experiments of fresh phytoplankton. We propose that an important yet mostly overlooked consideration in previous upscalinG approaches is the proportion of the relative reactive POC classes reachinG the seafloor in addition to their reactivity. The approach presented is applicable to both steady-state and non-steady state scenarios, and links POC deGradation kinetics in sedimentary environments to water depth and the POC rain rate to the seafloor.
Ali Dolati - One of the best experts on this subject based on the ideXlab platform.
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Stochastic Comparisons between the Extreme Claim Amounts from Two HeteroGeneous Portfolios in the Case of Transmuted-G Model
North American Actuarial Journal, 2020Co-Authors: Hossein Nadeb, Hamzeh Torabi, Ali DolatiAbstract:Let Xλ1,…,Xλn be independent and non-neGative random variables belonG to the transmuted-G Model and let Yi=IpiXλi,i=1,…,n, where Ip1,…,Ipn are independent Bernoulli random variables independent of ...
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Stochastic comparisons between the extreme claim amounts from two heteroGeneous portfolios in the case of transmuted-G Model
arXiv: Applications, 2018Co-Authors: Hossein Nadeb, Hamzeh Torabi, Ali DolatiAbstract:Let $X_{\lambda_1}, \ldots , X_{\lambda_n}$ be independent non-neGative random variables belonG to the transmuted-G Model and let $Y_i=I_{p_i} X_{\lambda_i}$, $i=1,\ldots,n$, where $I_{p_1}, \ldots, I_{p_n}$ are independent Bernoulli random variables independent of $X_{\lambda_i}$'s, with ${\rm E}[I_{p_i}]=p_i$, $i=1,\ldots,n$. In actuarial sciences, $Y_i$ corresponds to the claim amount in a portfolio of risks. In this paper we compare the smallest and the larGest claim amounts of two sets of independent portfolios belonGinG to the transmuted-G Model, in the sense of usual stochastic order, hazard rate order and dispersive order, when the variables in one set have the parameters $\lambda_1,\ldots,\lambda_n$ and the variables in the other set have the parameters $\lambda^{*}_1,\ldots,\lambda^{*}_n$. For illustration we apply the results to the transmuted-G exponential and the transmuted-G Weibull Models.
