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@ -80,7 +80,9 @@
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\setbeamerfont{page number in head/foot}{size=\large}
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\setbeamerfont{page number in head/foot}{size=\large}
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\setbeamertemplate{footline}[frame number]
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%\setbeamertemplate{footline}[frame number] number in footer
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\setbeamertemplate{footline}{}
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\title[A new mathematical model for verifying the Navier-Stokes compatibility of 4D flow MRI data]{ A new mathematical model for verifying the Navier-Stokes compatibility of 4D flow MRI data}
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\title[A new mathematical model for verifying the Navier-Stokes compatibility of 4D flow MRI data]{ A new mathematical model for verifying the Navier-Stokes compatibility of 4D flow MRI data}
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@ -113,14 +115,21 @@ University of Groningen\\[0.5cm]
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\end{frame}
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\end{frame}
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\section{4D flow MRI}
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\section[4D flow MRI]{4D flow MRI}
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\begin{frame}
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\begin{frame}
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\frametitle{4D flow MRI}
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\frametitle{4D flow MRI}
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\begin{columns}[c]
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\begin{columns}[c]
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\column{.55\textwidth} % Left column and width
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\column{.55\textwidth} % Left column and width
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\footnotesize
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\footnotesize
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4D flow MRI has been shown potential in the assesment of blood flow dynamics in heart and large arteries, allowing wide variety of options for visualization and quantification.
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4D flow MRI has been shown potential in the assesment of blood flow dynamics in the heart and also large arteries, allowing wide variety of options for visualization and quantification.
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Some advantages respect others techniques:
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\begin{itemize}
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\item Full 3D coverage of the region of interest
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\item Retrospective plane positioning
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\item Rich post-proccesing: derived parameters
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\end{itemize}
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\column{.5\textwidth} % Right column and width
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\column{.5\textwidth} % Right column and width
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@ -145,7 +154,7 @@ We want to introduce a novel measure for quantify the quality of the 4D flow mea
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\end{frame}
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\end{frame}
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\section{The corrector field}
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\section[]{The corrector field}
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\begin{frame}
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\begin{frame}
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\frametitle{The corrector field}
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\frametitle{The corrector field}
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@ -157,22 +166,24 @@ We assume a perfect physical velocity field $\vec{u}$
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\end{eqnarray*}
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\end{eqnarray*}
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And a corrector field $\vec{w}$ which satisfies:
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And a corrector field $\vec{w}$ which satisfies:
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\begin{align}
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\begin{align}
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\vec{u} & \approx \vec{u}_{meas} + \vec{w} \quad \text{in} \quad \Omega \label{eq:corrector} \\
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\vec{u} & \approx \vec{u}_{meas} + \vec{w} \quad \text{in} \quad \Omega \label{eq:corrector} \\
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\nabla \cdot \vec w & = 0 \quad \text{in} \quad \Omega \label{eq:correctorDiv} \\
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\nabla \cdot \vec w & = 0 \quad \text{in} \quad \Omega \label{eq:correctorDiv} \\
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\vec w & = \vec 0 \quad \text{on} \quad \partial \Omega \label{eq:correctorBC}
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\vec w & = \vec 0 \quad \text{on} \quad \partial \Omega \label{eq:correctorBC}
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\end{align}
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\end{align}
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$\vec{w}$ measures the level of agreedment of the 4D flow measures respect to the Navier-Stokes equations.
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The corrector field $\vec{w}$ measures the level of agreedment of the 4D flow measures respect to the Navier-Stokes equations.
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\end{frame}
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\end{frame}
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\section[Synthetic data]{Experiments using synthetic data }
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\begin{frame}
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\begin{frame}
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\frametitle{Numerical tests}
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\frametitle{Numerical tests}
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\begin{columns}[c]
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\column{.6\textwidth} % Left column and width
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\footnotesize
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\footnotesize
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We tested the corrector using CFD simulations as a measurements, in the following testcases:
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We tested the corrector using CFD simulations as a measurements, in the following testcases:
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@ -180,25 +191,107 @@ We tested the corrector using CFD simulations as a measurements, in the followin
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\item Womersley flow in a cilinder
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\item Womersley flow in a cilinder
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\item Navier-Stokes simulations in an aortic mesh
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\item Navier-Stokes simulations in an aortic mesh
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\end{itemize}
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\end{itemize}
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Also perturbations were added into the measurements:
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Also perturbations were added into the measurements:
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\begin{itemize}
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\begin{itemize}
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\item velocity aliasing
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\item velocity aliasing (varying the $venc$ parameter)
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\item additive noise
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\item additive noise (setting SNR in decibels)
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\item simulated k-space undersampling
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\item simulated k-space undersampling (compressed sensing for the reconstruction)
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\end{itemize}
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\end{itemize}
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All simulations were done using a stabilized finite element method implemented in FEniCS. Afterwards, all numerical simulations were interpolated into a voxel-type structured mesh
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\end{frame}
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\begin{frame}
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\frametitle{Numerical tests: details}
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\begin{columns}[c]
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\column{.6\textwidth} % Left column and width
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\footnotesize
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\textbf{Channel:}
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\begin{itemize}
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\item Convective term was neglected
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\item Non-slip condition at walls
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\item Oscilatory pressure at $\Gamma_{inlet}$
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\end{itemize}
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\column{.5\textwidth} % Right column and width
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\column{.5\textwidth} % Right column and width
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\footnotesize
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\footnotesize
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\begin{figure}[!hbtp]
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\begin{figure}[!hbtp]
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\begin{center}
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\begin{center}
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\includegraphics[height=\textwidth]{images/aorta_blender.png}
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\includegraphics[height=0.3\textwidth]{images/cilinder_2.png}
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\caption{Aortic mesh }
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\end{center}
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\end{center}
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\end{figure}
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\end{figure}
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\end{columns}
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\end{columns}
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\begin{columns}[c]
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\column{.6\textwidth} % Left column and width
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\footnotesize
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\textbf{Aorta}
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\begin{itemize}
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\item a mild coartation was added in the descending aorta
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\item $u_{inlet}$ simulates a cardiac cycle
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\item 3-element Windkessel for the outlets
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\item Non-slip condition at walls
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\end{itemize}
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\column{.5\textwidth} % Right column and width
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\footnotesize
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\begin{figure}[!hbtp]
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\begin{center}
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\includegraphics[height=0.7\textwidth]{images/aorta_blender.png}
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\caption{\tiny{Channel mesh}}
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\end{center}
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\end{figure}
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\end{columns}
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\end{frame}
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\end{frame}
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\begin{frame}
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\frametitle{Results: aliasing and noise}
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\footnotesize
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For comparison we defined a perfect corrector field as: $\delta \vec u = \vec u_{ref} - \vec u_{meas}$
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\begin{figure}[!hbtp]
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\begin{center}
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\includegraphics[height=0.5\textwidth]{images/perturbation_pres.png}
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\caption{Different perturbation scenarios}
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\end{center}
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\end{figure}
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\end{frame}
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\begin{frame}
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\frametitle{Results: undersampling}
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\footnotesize
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\begin{figure}[!hbtp]
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\begin{center}
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\includegraphics[height=0.6\textwidth]{images/undersampling_final.png}
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\caption{Different perturbation scenarios}
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\end{center}
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\end{figure}
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\end{frame}
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\section[4D flow data]{Experiments using real 4D flow data }
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\begin{frame}
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\begin{frame}
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\frametitle{Experiments}
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\frametitle{Experiments}
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\footnotesize
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\footnotesize
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@ -211,15 +304,7 @@ Also perturbations were added into the measurements:
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\section{Results}
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\begin{frame}
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\frametitle{Results}
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\footnotesize
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results for the synthetic data. Comparison againts the perfect correction field: du.
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\end{frame}
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\begin{frame}
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\begin{frame}
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\frametitle{Results}
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\frametitle{Results}
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@ -230,14 +315,6 @@ results for experimental phantom
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\end{frame}
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\end{frame}
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\begin{frame}
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\frametitle{Results}
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\footnotesize
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results in healthy volunteers
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\end{frame}
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