Functional neuroimaging is becoming a valuable tool in cognitive research and clinical applicatio... more Functional neuroimaging is becoming a valuable tool in cognitive research and clinical applications. The clinical context brings specific constraints that include the requirement of a high channel count to cover the whole head, high sensitivity for single event detection, and portability for long-term bedside monitoring. For epilepsy and stroke monitoring, the combination of electroencephalography (EEG) and functional near-infrared spectroscopy (NIRS) is expected to provide useful clinical information, and efforts have been deployed to create prototypes able to simultaneously acquire both measurement modalities. However, to the best of our knowledge, existing systems lack portability, NIRS sensitivity, or have low channel count. We present a battery-powered, portable system with potentially up to 32 EEG channels, 32 NIRS light sources, and 32 detectors. Avalanche photodiodes allow for high NIRS sensitivity and the autonomy of the system is over 24 h. A reduced channel count prototype with 8 EEG channels, 8 sources, and 8 detectors was tested on phantoms. Further validation was done on five healthy adults using a visual stimulation protocol to detect local hemodynamic changes and visually evoked potentials. Results show good concordance with literature regarding functional activations and suggest sufficient performance for clinical use, provided some minor adjustments were made.
This paper investigates the impact of social-network based political connections on firm value. W... more This paper investigates the impact of social-network based political connections on firm value. We focus on the networks of university classmates and alumni among directors of U.S. public firms and congressmen. Comparing firms connected to elected versus defeated politicians in the Regression Discontinuity Design of close elections from 2000 to 2008, we provide evidence that political connections enhance firm value. However, the value of political connections varies in a more complex way than expected. While connections to powerful members of the Senate generate strong positive impact on firm value, connections to newly elected congressmen are less valuable to firms than connections to state-level politicians defeated in those elections. As a result, a director's connection to an elected congressman causes a Weighted Average Treatment Effect on Cumulative Abnormal Returns of-2.65% surrounding the election date. Our results are robust and consistent through various specifications, parametric and nonparametric, with different outcome measures and social network definitions, and across many subsamples. Overall, our study identifies the value of political connections through social networks, uncovers its variation across different politicians' backgrounds, and stresses the importance of state-level political connections.
Functional neuroimaging is becoming a valuable tool in cognitive research and clinical applicatio... more Functional neuroimaging is becoming a valuable tool in cognitive research and clinical applications. The clinical context brings specific constraints that include the requirement of a high channel count to cover the whole head, high sensitivity for single event detection, and portability for long-term bedside monitoring. For epilepsy and stroke monitoring, the combination of electroencephalography (EEG) and functional near-infrared spectroscopy (NIRS) is expected to provide useful clinical information, and efforts have been deployed to create prototypes able to simultaneously acquire both measurement modalities. However, to the best of our knowledge, existing systems lack portability, NIRS sensitivity, or have low channel count. We present a battery-powered, portable system with potentially up to 32 EEG channels, 32 NIRS light sources, and 32 detectors. Avalanche photodiodes allow for high NIRS sensitivity and the autonomy of the system is over 24 h. A reduced channel count prototype with 8 EEG channels, 8 sources, and 8 detectors was tested on phantoms. Further validation was done on five healthy adults using a visual stimulation protocol to detect local hemodynamic changes and visually evoked potentials. Results show good concordance with literature regarding functional activations and suggest sufficient performance for clinical use, provided some minor adjustments were made.
This paper investigates the impact of social-network based political connections on firm value. W... more This paper investigates the impact of social-network based political connections on firm value. We focus on the networks of university classmates and alumni among directors of U.S. public firms and congressmen. Comparing firms connected to elected versus defeated politicians in the Regression Discontinuity Design of close elections from 2000 to 2008, we provide evidence that political connections enhance firm value. However, the value of political connections varies in a more complex way than expected. While connections to powerful members of the Senate generate strong positive impact on firm value, connections to newly elected congressmen are less valuable to firms than connections to state-level politicians defeated in those elections. As a result, a director's connection to an elected congressman causes a Weighted Average Treatment Effect on Cumulative Abnormal Returns of-2.65% surrounding the election date. Our results are robust and consistent through various specifications, parametric and nonparametric, with different outcome measures and social network definitions, and across many subsamples. Overall, our study identifies the value of political connections through social networks, uncovers its variation across different politicians' backgrounds, and stresses the importance of state-level political connections.
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Papers by Dang Nguyen