The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
K. Nozaki - One of the best experts on this subject based on the ideXlab platform.
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Threshold of carbonate saturation state determined by a CO2 Control Experiment
Biogeosciences Discussions, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies suggest that carbonate dissolution will occur in polar regions and in the deep-sea oceans where saturation state with respect to carbonate minerals (Ω) will be <1 by 2100. However, carbonate in coral reefs distributed in tropical zones will not dissolve because the major carbonate in such reefs is aragonite, and the saturation state with respect to aragonite (Ω_a) is >1. Recent reports demonstrated nocturnal carbonate dissolution reefs, despite Ω_a > 1, probably relate to the dissolution of the minor reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined, and it is unknown whether these dissolution processes actually occur under natural conditions. This work describes the measurement of the dissolution rates of coral aragonite and Mg calcite excreted by marine organisms under conditions of Ω_a > 1 with Controlled seawater pCO2. Laboratory Experimental data of the present study show that bulk carbonate sediments sampled from a coral reef start to dissolve when Ω_a = 3.7, and dissolution rates increase with falling Ω_a. Mg-calcite derived from foraminifera and coralline algae dissolved when Ω_a reached 3.4, whereas coralline aragonite started to dissolve when Ω_a was almost 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminifera and coralline algae in reef sediment.
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Threshold of carbonate saturation state determined by CO2 Control Experiment
Biogeosciences, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies have suggested that carbonate dissolution will occur in polar regions and in the deep sea where saturation state with respect to carbonate minerals (Ω) will be 1. This is probably related to the dissolution of reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined. We designed an Experimental dissolution system with conditions mimicking those of a natural coral reef, and measured the dissolution rates of aragonite in corals, and of Mg-calcite excreted by other marine organisms, under conditions of Ωa > 1, with Controlled seawater pCO2. The Experimental data show that dissolution of bulk carbonate sediments sampled from a coral reef occurs at Ωa values of 3.7 to 3.8. Mg-calcite derived from foraminifera and coralline algae dissolves at Ωa values between 3.0 and 3.2, and coralline aragonite starts to dissolve when Ωa = 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminiferans and coralline algae in reef sediments.
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threshold of carbonate saturation state determined by co 2 Control Experiment
Biogeosciences, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies have suggested that carbonate dissolution will occur in polar regions and in the deep sea where saturation state with respect to carbonate minerals (Ω) will be 1. This is probably related to the dissolution of reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined. We designed an Experimental dissolution system with conditions mimicking those of a natural coral reef, and measured the dissolution rates of aragonite in corals, and of Mg-calcite excreted by other marine organisms, under conditions of Ωa > 1, with Controlled seawater pCO2. The Experimental data show that dissolution of bulk carbonate sediments sampled from a coral reef occurs at Ωa values of 3.7 to 3.8. Mg-calcite derived from foraminifera and coralline algae dissolves at Ωa values between 3.0 and 3.2, and coralline aragonite starts to dissolve when Ωa = 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminiferans and coralline algae in reef sediments.
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Threshold of carbonate saturation state determined by a CO<sub>2</sub> Control Experiment
Biogeosciences Discussions, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. Kato, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies suggest that carbonate dissolution will occur in polar regions and in the deep-sea oceans where saturation state with respect to carbonate minerals (Ω) will be <1 by 2100. However, carbonate in coral reefs distributed in tropical zones will not dissolve because the major carbonate in such reefs is aragonite, and the saturation state with respect to aragonite (Ω_a) is >1. Recent reports demonstrated nocturnal carbonate dissolution reefs, despite Ω_a > 1, probably relate to the dissolution of the minor reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined, and it is unknown whether these dissolution processes actually occur under natural conditions. This work describes the measurement of the dissolution rates of coral aragonite and Mg calcite excreted by marine organisms under conditions of Ω_a > 1 with Controlled seawater pCO2. Laboratory Experimental data of the present study show that bulk carbonate sediments sampled from a coral reef start to dissolve when Ω_a = 3.7, and dissolution rates increase with falling Ω_a. Mg-calcite derived from foraminifera and coralline algae dissolved when Ω_a reached 3.4, whereas coralline aragonite started to dissolve when Ω_a was almost 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminifera and coralline algae in reef sediment.
Toshiharu Sugie - One of the best experts on this subject based on the ideXlab platform.
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development and Control Experiment of the trident snake robot
IEEE-ASME Transactions on Mechatronics, 2010Co-Authors: Masato Ishikawa, Yuki Minami, Toshiharu SugieAbstract:This paper is concerned with the development of the trident snake robot , a new example of nonholonomic mobile robot proposed by the authors. The robot has three-pointed shape composed of a center block and three branches, each of which has a passive nonslide wheel. It is modeled as a nonnilpotent driftless system with two generators; its Control is a challenging problem, not only because it cannot be treated by continuous Control law, but because it cannot be converted to any easy class of nonholonomic systems such as chained form. In this paper, we realized the one-link trident snake robot and applied a periodic Control algorithm based on Lie bracket motion. Effectiveness of the proposed algorithm is examined with Control Experiments.
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development and Control Experiment of the trident snake robot
Conference on Decision and Control, 2006Co-Authors: Masato Ishikawa, Yuki Minami, Toshiharu SugieAbstract:This paper is concerned with development of the trident snake robot, a new example of nonholonomic mobile robot proposed by the authors. The robot has three-pointed shape composed of a center block and three branches, each of which has a passive non-slide wheel. It is modeled as a non-nilpotent driftless system with two generators; its Control is a challenging problem, not only because it cannot be treated by continuous Control law, but because it cannot be converted to any easy class of nonholonomic systems such as chained form. In this paper, we realized the 1-link trident snake robot and applied a periodic Control algorithm based on Lie bracket motion. Effectiveness of the proposed algorithm is examined with Control Experiments.
Yawen Tang - One of the best experts on this subject based on the ideXlab platform.
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prevalence of tidal interactions among local seyfert galaxies the Control Experiment
The Astrophysical Journal, 2008Co-Authors: Yawen Tang, C Y Kuo, Jeremy LimAbstract:We test whether there is a relation between the observed tidal interactions and Seyfert activity by imaging in atomic hydrogen (H I 27) inactive galaxies at the same spatial resolution and detection threshold as the Seyfert sample. This Control sample of inactive galaxies was closely matched in Hubble type, range in size, and inclination and has roughly comparable galaxy optical luminosity to the Seyfert galaxies. We find that only ~15% of the galaxies in our Control sample are disturbed in H I, whereas the remaining ~85% show no disturbances whatsoever in H I. Even at a spatial resolution of ~10 kpc, none of the latter galaxies show appreciable H I disturbances reminiscent of tidal features. In a companion paper we report results from the first systematic imaging survey of Seyfert galaxies in H I gas. We find that only ~28% of the 18 Seyfert galaxies in that sample are visibly disturbed in optical starlight. By contrast, ~94% of the same Seyfert galaxies are disturbed spatially and usually also kinematically in H I gas on galactic scales of 20 kpc. In at least ~67% and up to perhaps ~94% of cases, the observed disturbances can be traced to tidal interactions with neighboring galaxies detected also in H I. The dramatic contrast between the observed prevalence of H I disturbances in the Seyfert and Control samples implicates tidal interactions in initiating events that lead to luminous Seyfert activity in a large fraction of local disk galaxies.
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prevalence of tidal interactions among local seyfert galaxies the Control Experiment
arXiv: Astrophysics, 2008Co-Authors: Yawen Tang, C Y Kuo, Jeremy LimAbstract:We test whether there is a relation between the observed tidal interactions and Seyfert activity by imaging in HI twenty inactive galaxies at the same spatial resolution and detection threshold as the Seyfert sample. This Control sample of inactive galaxies were closely matched in Hubble type, range in size and inclination, and have roughly comparable galaxy optical luminosity to the Seyfert galaxies. We find that only ~15% of the galaxies in our Control sample are disturbed in HI, whereas the remaining ~85% show no disturbances whatsoever in HI. Even at a spatial resolution of ~10 kpc, none of the latter galaxies show appreciable HI disturbances reminiscent of tidal features. In a companion paper (Kuo et al. 2008), we report results from the first systematic imaging survey of Seyfert galaxies in atomic hydrogen (HI) gas. We find that only ~28% of the eighteen Seyfert galaxies in that sample are visibly disturbed in optical starlight. By contrast, ~94% of the same Seyfert galaxies are disturbed spatially and usually also kinematically in HI gas on galactic scales of >~20 kpc. In at least ~67% and up to perhaps ~94% of cases, the observed disturbances can be traced to tidal interactions with neighboring galaxies detected also in HI. The dramatic contrast between the observed prevalence of HI disturbances in the Seyfert and Control samples implicates tidal interactions in initiating events that lead to luminous Seyfert activity in a large fraction of local disk galaxies.
S Yamamoto - One of the best experts on this subject based on the ideXlab platform.
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Threshold of carbonate saturation state determined by a CO2 Control Experiment
Biogeosciences Discussions, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies suggest that carbonate dissolution will occur in polar regions and in the deep-sea oceans where saturation state with respect to carbonate minerals (Ω) will be <1 by 2100. However, carbonate in coral reefs distributed in tropical zones will not dissolve because the major carbonate in such reefs is aragonite, and the saturation state with respect to aragonite (Ω_a) is >1. Recent reports demonstrated nocturnal carbonate dissolution reefs, despite Ω_a > 1, probably relate to the dissolution of the minor reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined, and it is unknown whether these dissolution processes actually occur under natural conditions. This work describes the measurement of the dissolution rates of coral aragonite and Mg calcite excreted by marine organisms under conditions of Ω_a > 1 with Controlled seawater pCO2. Laboratory Experimental data of the present study show that bulk carbonate sediments sampled from a coral reef start to dissolve when Ω_a = 3.7, and dissolution rates increase with falling Ω_a. Mg-calcite derived from foraminifera and coralline algae dissolved when Ω_a reached 3.4, whereas coralline aragonite started to dissolve when Ω_a was almost 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminifera and coralline algae in reef sediment.
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Threshold of carbonate saturation state determined by CO2 Control Experiment
Biogeosciences, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies have suggested that carbonate dissolution will occur in polar regions and in the deep sea where saturation state with respect to carbonate minerals (Ω) will be 1. This is probably related to the dissolution of reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined. We designed an Experimental dissolution system with conditions mimicking those of a natural coral reef, and measured the dissolution rates of aragonite in corals, and of Mg-calcite excreted by other marine organisms, under conditions of Ωa > 1, with Controlled seawater pCO2. The Experimental data show that dissolution of bulk carbonate sediments sampled from a coral reef occurs at Ωa values of 3.7 to 3.8. Mg-calcite derived from foraminifera and coralline algae dissolves at Ωa values between 3.0 and 3.2, and coralline aragonite starts to dissolve when Ωa = 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminiferans and coralline algae in reef sediments.
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threshold of carbonate saturation state determined by co 2 Control Experiment
Biogeosciences, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies have suggested that carbonate dissolution will occur in polar regions and in the deep sea where saturation state with respect to carbonate minerals (Ω) will be 1. This is probably related to the dissolution of reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined. We designed an Experimental dissolution system with conditions mimicking those of a natural coral reef, and measured the dissolution rates of aragonite in corals, and of Mg-calcite excreted by other marine organisms, under conditions of Ωa > 1, with Controlled seawater pCO2. The Experimental data show that dissolution of bulk carbonate sediments sampled from a coral reef occurs at Ωa values of 3.7 to 3.8. Mg-calcite derived from foraminifera and coralline algae dissolves at Ωa values between 3.0 and 3.2, and coralline aragonite starts to dissolve when Ωa = 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminiferans and coralline algae in reef sediments.
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Threshold of carbonate saturation state determined by a CO<sub>2</sub> Control Experiment
Biogeosciences Discussions, 2011Co-Authors: S Yamamoto, M. Terai, A. Watanabe, Hajime Kayanne, A. Negishi, K. Kato, K. NozakiAbstract:Abstract. Acidification of the oceans by increasing anthropogenic CO2 emissions will cause a decrease in biogenic calcification and an increase in carbonate dissolution. Previous studies suggest that carbonate dissolution will occur in polar regions and in the deep-sea oceans where saturation state with respect to carbonate minerals (Ω) will be <1 by 2100. However, carbonate in coral reefs distributed in tropical zones will not dissolve because the major carbonate in such reefs is aragonite, and the saturation state with respect to aragonite (Ω_a) is >1. Recent reports demonstrated nocturnal carbonate dissolution reefs, despite Ω_a > 1, probably relate to the dissolution of the minor reef carbonate (Mg-calcite), which is more soluble than aragonite. However, the threshold of Ω for the dissolution of natural sediments has not been clearly determined, and it is unknown whether these dissolution processes actually occur under natural conditions. This work describes the measurement of the dissolution rates of coral aragonite and Mg calcite excreted by marine organisms under conditions of Ω_a > 1 with Controlled seawater pCO2. Laboratory Experimental data of the present study show that bulk carbonate sediments sampled from a coral reef start to dissolve when Ω_a = 3.7, and dissolution rates increase with falling Ω_a. Mg-calcite derived from foraminifera and coralline algae dissolved when Ω_a reached 3.4, whereas coralline aragonite started to dissolve when Ω_a was almost 1.0. We show that nocturnal carbonate dissolution of coral reefs occurs mainly by the dissolution of foraminifera and coralline algae in reef sediment.
Jeremy Lim - One of the best experts on this subject based on the ideXlab platform.
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prevalence of tidal interactions among local seyfert galaxies the Control Experiment
The Astrophysical Journal, 2008Co-Authors: Yawen Tang, C Y Kuo, Jeremy LimAbstract:We test whether there is a relation between the observed tidal interactions and Seyfert activity by imaging in atomic hydrogen (H I 27) inactive galaxies at the same spatial resolution and detection threshold as the Seyfert sample. This Control sample of inactive galaxies was closely matched in Hubble type, range in size, and inclination and has roughly comparable galaxy optical luminosity to the Seyfert galaxies. We find that only ~15% of the galaxies in our Control sample are disturbed in H I, whereas the remaining ~85% show no disturbances whatsoever in H I. Even at a spatial resolution of ~10 kpc, none of the latter galaxies show appreciable H I disturbances reminiscent of tidal features. In a companion paper we report results from the first systematic imaging survey of Seyfert galaxies in H I gas. We find that only ~28% of the 18 Seyfert galaxies in that sample are visibly disturbed in optical starlight. By contrast, ~94% of the same Seyfert galaxies are disturbed spatially and usually also kinematically in H I gas on galactic scales of 20 kpc. In at least ~67% and up to perhaps ~94% of cases, the observed disturbances can be traced to tidal interactions with neighboring galaxies detected also in H I. The dramatic contrast between the observed prevalence of H I disturbances in the Seyfert and Control samples implicates tidal interactions in initiating events that lead to luminous Seyfert activity in a large fraction of local disk galaxies.
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prevalence of tidal interactions among local seyfert galaxies the Control Experiment
arXiv: Astrophysics, 2008Co-Authors: Yawen Tang, C Y Kuo, Jeremy LimAbstract:We test whether there is a relation between the observed tidal interactions and Seyfert activity by imaging in HI twenty inactive galaxies at the same spatial resolution and detection threshold as the Seyfert sample. This Control sample of inactive galaxies were closely matched in Hubble type, range in size and inclination, and have roughly comparable galaxy optical luminosity to the Seyfert galaxies. We find that only ~15% of the galaxies in our Control sample are disturbed in HI, whereas the remaining ~85% show no disturbances whatsoever in HI. Even at a spatial resolution of ~10 kpc, none of the latter galaxies show appreciable HI disturbances reminiscent of tidal features. In a companion paper (Kuo et al. 2008), we report results from the first systematic imaging survey of Seyfert galaxies in atomic hydrogen (HI) gas. We find that only ~28% of the eighteen Seyfert galaxies in that sample are visibly disturbed in optical starlight. By contrast, ~94% of the same Seyfert galaxies are disturbed spatially and usually also kinematically in HI gas on galactic scales of >~20 kpc. In at least ~67% and up to perhaps ~94% of cases, the observed disturbances can be traced to tidal interactions with neighboring galaxies detected also in HI. The dramatic contrast between the observed prevalence of HI disturbances in the Seyfert and Control samples implicates tidal interactions in initiating events that lead to luminous Seyfert activity in a large fraction of local disk galaxies.