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973 results on '"Brandt, Martin"'

103. Electrical detection of spin echoes for phosphorus donors in silicon

Author

Huebl, Hans, Hoehne, Felix, Grolik, Benno, Stegner, Andre R., Stutzmann, Martin, and Brandt, Martin S.

Subjects
Quantum Physics
Abstract

The electrical detection of spin echoes via echo tomography is used to observe decoherence processes associated with the electrical readout of the spin state of phosphorus donor electrons in silicon near a SiO$_2$ interface. Using the Carr-Purcell pulse sequence, an echo decay with a time constant of $1.7\pm0.2 \rm{\mu s}$ is observed, in good agreement with theoretical modeling of the interaction between donors and paramagnetic interface states. Electrical spin echo tomography thus can be used to study the spin dynamics in realistic spin qubit devices for quantum information processing., Comment: 14 pages, 3 figures

Published
2007
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105. Phosphorus donors in highly strained silicon

Author

Huebl, Hans, Stegner, Andre R., Stutzmann, Martin, Brandt, Martin S., Vogg, Guenther, Bensch, Frank, Rauls, Eva, and Gerstmann, Uwe

Subjects
Condensed Matter - Materials Science
Abstract

The hyperfine interaction of phosphorus donors in fully strained Si thin films grown on virtual Si$_{1-x}$Ge$_x$ substrates with $x\leq 0.3$ is determined via electrically detected magnetic resonance. For highly strained epilayers, hyperfine interactions as low as 0.8 mT are observed, significantly below the limit predicted by valley repopulation. Within a Green's function approach, density functional theory (DFT) shows that the additional reduction is caused by the volume increase of the unit cell and a local relaxation of the Si ligands of the P donor., Comment: 12 pages, 3 figures

Published
2006
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106. Füllungssteuerung bei Ottomotoren

Author

Brandt, Martin, Grossmann, Alex, Deissler, Markus, Kirsten, Kurt, Bäuerle, Michael, Rauscher, Martin, Müller, Jochen, Samenfink, Wolfgang, Reif, Konrad, and Reif, Konrad, Series editor

Published
2017
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109. Satellite-observed pantropical carbon dynamics

Author

Fan, Lei, Wigneron, Jean-Pierre, Ciais, Philippe, Chave, Jérôme, Brandt, Martin, Fensholt, Rasmus, Saatchi, Sassan S., Bastos, Ana, Al-Yaari, Amen, Hufkens, Koen, Qin, Yuanwei, Xiao, Xiangming, Chen, Chi, Myneni, Ranga B., Fernandez-Moran, Roberto, Mialon, Arnaud, Rodriguez-Fernandez, N. J., Kerr, Yann, Tian, Feng, and Peñuelas, Josep

Published
2019
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113. Mega-cities dominate China’s urban greening

Author

Zhang, Xiaoxin, primary, Brandt, Martin, additional, Tong, Xiaoye, additional, Tong, Xiaowei, additional, Zhang, Wenmin, additional, Reiner, Florian, additional, Li, Sizhuo, additional, Tian, Feng, additional, Yue, Yuemin, additional, zhou, weiqi, additional, Chen, Bin, additional, Xiao, Xiangming, additional, and Fensholt, Rasmus, additional

Published
2023
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115. FAIR Data Cube, a FAIR data infrastructure for integrated multi-omics data analysis

Author

Liao, Xiaofeng, primary, Niehues, Anna, additional, de Visser, Casper, additional, Huang, Junda, additional, Doornbos, Cenna, additional, Ederveen, Thomas H.A., additional, Kulkarni, Purva, additional, van der Velde, K. Joeri, additional, Swertz, Morris A., additional, Brandt, Martin, additional, van Gool, Alain J., additional, and 't Hoen, Peter A.C., additional

Published
2023
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117. Global patterns and drivers of tropical aboveground carbon changes

Author

Feng, Yu, Ciais, Philippe, Wigneron, Jean-Pierre, Xu, Yidi, Ziegler, Alan D., van Wees, Dave, Fendrich, Arthur Nicolaus, Spracklen, Dominick V., Sitch, Stephen, Brandt, Martin, Li, Wei, Fan, Lei, Li, Xiaojun, Wu, Jie, and Zeng, Zhenzhong

Abstract

Tropical terrestrial ecosystems play an important role in modulating the global carbon balance. However, the complex dynamics and factors controlling tropical aboveground live biomass carbon (AGC) are not fully understood. Here, using remotely sensed observations, we find a moderate net AGC sink of 0.21 ± 0.06 PgC yr−1throughout the global tropics from 2010 to 2020. This arises from a gross loss of −1.79 PgC yr−1offset by a marked gain of 2.01 ± 0.06 PgC yr−1. Fire emissions in non-forested African shrubland/savanna biomes, coupled with post-fire carbon recovery, substantially dominated the interannual variability of tropical AGC. Fire radiative power was identified as the primary determinant of the spatial variability in AGC gains, with soil moisture also playing a crucial role in shaping trends. We highlight the dominant roles of anthropogenic and hydroclimatic determinants in orchestrating tropical land carbon dynamics and advocate for land management to conserve indispensable ecosystem services worldwide.

Published
2024
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122. FORMS: Forest Multiple Source height, wood volume, and biomass maps in France at 10 to 30 m resolution based on Sentinel-1, Sentinel-2, and Global Ecosystem Dynamics Investigation (GEDI) data with a deep learning approach.

Author

Schwartz, Martin, Ciais, Philippe, De Truchis, Aurélien, Chave, Jérôme, Ottlé, Catherine, Vega, Cedric, Wigneron, Jean-Pierre, Nicolas, Manuel, Jouaber, Sami, Liu, Siyu, Brandt, Martin, and Fayad, Ibrahim

Subjects
DEEP learning, ECOSYSTEM dynamics, ECOLOGICAL disturbances, CARBON sequestration in forests, WOOD, FOREST biomass, FOREST management
Abstract

The contribution of forests to carbon storage and biodiversity conservation highlights the need for accurate forest height and biomass mapping and monitoring. In France, forests are managed mainly by private owners and divided into small stands, requiring 10 to 50 m spatial resolution data to be correctly separated. Further, 35 % of the French forest territory is covered by mountains and Mediterranean forests which are managed very extensively. In this work, we used a deep-learning model based on multi-stream remote-sensing measurements (NASA's Global Ecosystem Dynamics Investigation (GEDI) lidar mission and ESA's Copernicus Sentinel-1 and Sentinel-2 satellites) to create a 10 m resolution canopy height map of France for 2020 (FORMS-H). In a second step, with allometric equations fitted to the French National Forest Inventory (NFI) plot data, we created a 30 m resolution above-ground biomass density (AGBD) map (Mg ha -1) of France (FORMS-B). Extensive validation was conducted. First, independent datasets from airborne laser scanning (ALS) and NFI data from thousands of plots reveal a mean absolute error (MAE) of 2.94 m for FORMS-H, which outperforms existing canopy height models. Second, FORMS-B was validated using two independent forest inventory datasets from the Renecofor permanent forest plot network and from the GLORIE forest inventory with MAE of 59.6 and 19.6 Mg ha -1 , respectively, providing greater performance than other AGBD products sampled over France. Finally, we compared FORMS-V (for volume) with wood volume estimations at the ecological region scale and obtained an R2 of 0.63 with an MAE of 30 m 3 ha -1. These results highlight the importance of coupling remote-sensing technologies with recent advances in computer science to bring material insights to climate-efficient forest management policies. Additionally, our approach is based on open-access data having global coverage and a high spatial and temporal resolution, making the maps reproducible and easily scalable. FORMS products can be accessed from 10.5281/zenodo.7840108 (Schwartz et al., 2023). [ABSTRACT FROM AUTHOR]

Published
2023
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123. Rural outmigration generates a carbon sink in South China karst.

Author

Chang, Jingyi, Yue, Yuemin, Tong, Xiaowei, Brandt, Martin, Zhang, Chunhua, Zhang, Xuemei, Qi, Xiangkun, and Wang, Kelin

Subjects
CARBON cycle, RURAL-urban migration, DESERTIFICATION, KARST, RURAL population, CITY dwellers, POPULATION statistics, GROUND vegetation cover, BIOMASS
Abstract

China karst is a global hotspot of increasing vegetation cover, with ecological conservation projects being considered as the main driver. New research using global datasets also indicates that rural outmigration has contributed to increasing biomass at national scale. However, the link between rural outmigration and vegetation cover increase has not been established at regional scale, and it remains unclear as to whether increases in biomass do, in fact, improve the environmental conditions. In this study, we use local field and statistical data on population density and rocky desertification areas to study population movements and changes in aboveground biomass in relation to rocky desertification in South China karst during 2000–2017. Our results show that the urban population in this region increased by 8.3 million people between 2005 and 2015, and the rural population decreased by 4.8 million people. We find that aboveground biomass increased most in rural areas with low human pressure, and that there was an almost linear relationship between increase in biomass and rural outmigration, with the highest increase in aboveground biomass density (1.5 MgC ha−1 yr−1) observed in areas where rural outmigration was highest, and the lowest increase in aboveground biomass density (1.1 MgC ha−1 yr−1) where rural outmigration was lowest. Rocky desertification areas decreased with a higher level of rural outmigration. Using local field data, our study confirmed that rural outmigration can generate a carbon sink at regional scale by reducing rocky desertification. [ABSTRACT FROM AUTHOR]

Published
2023
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125. FORMS: Forest Multiple Source height, wood volume, and biomass maps in France at 10 to 30 m resolution based on Sentinel-1, Sentinel-2, and GEDI data with a deep learning approach

Author

Schwartz, Martin, Ciais, Philippe, Truchis, Aurélien, Chave, Jérôme, Ottlé, Catherine, Vega, Cedric, Wigneron, Jean-Pierre, Nicolas, Manuel, Jouaber, Sami, Liu, Siyu, Brandt, Martin, and Fayad, Ibrahim

Abstract

The contribution of forests to carbon storage and biodiversity conservation highlights the need for accurate forest height and biomass mapping and monitoring. In France, forests are managed mainly by private owners and divided into small stands, requiring 10 to 50 m spatial resolution data to be correctly separated. Further, 35 % of the French forest territory is covered by mountains and Mediterranean forests which are managed very extensively. In this work, we used a deep-learning model based on multi-stream remote sensing measurements (NASA’s GEDI LiDAR mission and ESA’s Copernicus Sentinel 1 & 2 satellites) to create a 10 m resolution canopy height map of France for 2020 (FORMS-H). In a second step, with allometric equations fitted to the French National Forest Inventory (NFI) plot data, we created a 30 m resolution above-ground biomass density (AGBD) map (Mg ha-1) of France (FORMS-B). Extensive validation was conducted. First, independent datasets from Airborne Laser Scanning (ALS) and NFI data from thousands of plots reveal a mean absolute error (MAE) of 2.94 m for FORMS-H, which outperforms existing canopy height models. Second, FORMS-B was validated using two independent forest inventory datasets from the Renecofor permanent forest plot network and from the GLORIE forest inventory with MAE of 59.6 Mg ha-1 and 19.6 Mg.ha-1 respectively, providing greater performance than other AGBD products sampled over France. These results highlight the importance of coupling remote sensing technologies with recent advances in computer science to bring material insights to climate-efficient forest management policies. Additionally, our approach is based on open-access data having global coverage and a high spatial and temporal resolution, making the maps reproducible and easily scalable. FORMS products can be accessed from https://doi.org/10.5281/zenodo.7840108 (Schwartz et al., 2023).

Published
2023

126. Comments on Singh et al. (2022) 'Marine seismic surveys for hydrocarbon exploration: What's at stake?'

Author

Cawthra, Hayley C., Brandt, Martin B.C., Hicks, Nigel, and Khoza, David

Subjects
seismic surveys, climate change, CO2 capture and storage, just energy transition, marine life
Abstract

SIGNIFICANCE: We write this Commentary as a reply to Singh et al.(S Afr J Sci. 118(3/4), Art. #13420). We found that Singh et al.'s article did not adequately cover a rounded viewpoint on the topic, and we highlight a different perspective, calling for a balanced review in this regard. We base our argument on two premises. First, the literature study is incomplete, which creates a misleading perception that nothing is currently being done in South Africa to transition to a low carbon economy. Second, we comment on the statements made on seismic surveys. Herewith, we request that the authors consider a corrigendum that better reflects this research space, and call for more discussion on this topic.

Published
2023

129. Satellite passive microwaves reveal recent climate-induced carbon losses in African drylands

Author

Brandt, Martin, Wigneron, Jean-Pierre, Chave, Jerome, Tagesson, Torbern, Penuelas, Josep, Ciais, Philippe, Rasmussen, Kjeld, Tian, Feng, Mbow, Cheikh, Al-Yaari, Amen, Rodriguez-Fernandez, Nemesio, Schurgers, Guy, Zhang, Wenmin, Chang, Jinfeng, Kerr, Yann, Verger, Aleixandre, Tucker, Compton, Mialon, Arnaud, Rasmussen, Laura Vang, Fan, Lei, and Fensholt, Rasmus

Published
2018
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131. Deep learning enables image-based tree counting, crown segmentation, and height prediction at national scale

Author

Li, Sizhuo, primary, Brandt, Martin, additional, Fensholt, Rasmus, additional, Kariryaa, Ankit, additional, Igel, Christian, additional, Gieseke, Fabian, additional, Nord-Larsen, Thomas, additional, Oehmcke, Stefan, additional, Carlsen, Ask Holm, additional, Junttila, Samuli, additional, Tong, Xiaoye, additional, d’Aspremont, Alexandre, additional, and Ciais, Philippe, additional

Published
2023
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134. Biomass recovery after fires dominates the carbon sink of boreal forests over the last three decades

Author

Xu, Yidi, primary, Ciais, Philippe, additional, Li, Wei, additional, Saatchi, Sassan, additional, Santoro, Maurizio, additional, Cescatti, Alessandro, additional, Shchepashchenko, Dmitry, additional, He, Guojin, additional, Guido, Ceccherini, additional, He, Jiaying, additional, Fan, Lei, additional, Brandt, Martin, additional, Fensholt, Rasmus, additional, Wigneron, Jean-Pierre, additional, Kay, Heather, additional, Sitch, Stephen, additional, Bastos, Ana, additional, Bowing, Simon, additional, Ritter, François, additional, and Fayad, Ibrahim, additional

Published
2023
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137. Deep learning for mapping water bodies in the Sahel 

Author

de FLEURY, Mathilde, primary, Kergoat, Laurent, additional, Brandt, Martin, additional, Fensholt, Rasmus, additional, Kariryaa, Ankit, additional, Kovács, Gyula Mate, additional, Horion, Stéphanie, additional, and Grippa, Manuela, additional

Published
2023
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145. Füllungssteuerung

Author

Reif, Konrad, Brandt, Martin, Grossmann, Alex, Deissler, Markus, Bäuerle, Michael, Müller, Jochen, Samenfink, Wolfgang, Kirsten, Kurt, and Reif, Konrad, Series editor

Published
2014
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146. Füllungssteuerung

Author

Brandt, Martin, primary, Grossmann, Alex, additional, Deissler, Markus, additional, Kirsten, Kurt, additional, Bäuerle, Michael, additional, Rauscher, Martin, additional, Müller, Jochen, additional, Samenfink, Wolfgang, additional, and Reif, Konrad, additional

Published
2018
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149. The overlooked contribution of trees outside forests to tree cover and woody biomass across Europe.

Author

Siyu Liu, Brandt, Martin, Nord-Larsen, Thomas, Chave, Jerome, Reiner, Florian, Lang, Nico, Xiaoye Tong, Ciais, Philippe, Igel, Christian, Pascual, Adrian, Guerra-Hernandez, Juan, Sizhuo Li, Mugabowindekwe, Maurice, Saatchi, Sassan, Yuemin Yue, Zhengchao Chen, and Fensholt, Rasmus

Abstract

The article discusses the importance of accurately quantifying wood resources, especially trees outside closed canopy forests, at both national and local levels for sustainable forest management, carbon stock estimates, and various ecological and economic considerations. It highlights that many countries tend to focus their forest inventories on closed canopy forests leading to potential biases in national inventories and climate models.

Published
2023
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150. Nation-wide mapping of tree-level aboveground carbon stocks in Rwanda

Author

Mugabowindekwe, Maurice, primary, Brandt, Martin, additional, Chave, Jérôme, additional, Reiner, Florian, additional, Skole, David L., additional, Kariryaa, Ankit, additional, Igel, Christian, additional, Hiernaux, Pierre, additional, Ciais, Philippe, additional, Mertz, Ole, additional, Tong, Xiaoye, additional, Li, Sizhuo, additional, Rwanyiziri, Gaspard, additional, Dushimiyimana, Thaulin, additional, Ndoli, Alain, additional, Uwizeyimana, Valens, additional, Lillesø, Jens-Peter Barnekow, additional, Gieseke, Fabian, additional, Tucker, Compton J., additional, Saatchi, Sassan, additional, and Fensholt, Rasmus, additional

Published
2022
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