Summary
Created from Tikz source, then manually combined into one page:
\documentclass{standalone}
\usepackage{tikz}
\usepackage{pgfplots}
\usepgfplotslibrary{fillbetween}
\tikzset{
font={\fontsize{16pt}{12}\selectfont}}
\begin{document}
\begin{tikzpicture}[baseline]
\begin{axis}[
ticks=none,
no marks,
axis lines=none,
xmin=-0.1,xmax=1.1,
ymin=-0.5,ymax=0.5,
]
\addplot+[smooth,blue,name path=A,domain=0:1,samples=500] {1/2 * sqrt(abs((sin(deg(5*pi*x))+2) * (1/4 - (x - 1/2)^2)))};
\addplot+[smooth,blue,name path=B,domain=0:1,samples=500] {x * ln(x)};
\addplot+[blue!50] fill between[of=A and B,soft clip={domain=-4:4}];
\node[label={45:{$x$}},circle,fill,inner sep=2pt] at (axis cs:0.1,0) {};
\draw (axis cs:0.1, -1) -- (axis cs:0.1, 1);
\draw (axis cs:-1, 0) -- (axis cs:2, 0);
\node[label={0:$L_x$}] at (axis cs:0.1,0.4) {};
\node[color=blue] at (axis cs:.9,.4) {$\Omega$};
\end{axis}
\end{tikzpicture}
\hspace{1em}
\begin{tikzpicture}[baseline]
\begin{axis}[
ticks=none,
no marks,
axis lines=none,
xmin=-0.1,xmax=1.1,
ymin=-0.5,ymax=0.5,
]
\addplot+[smooth,red,name path=A,domain=0:1,samples=500] {1/2 * (1/2 * sqrt(abs((sin(deg(5*pi*x))+2) * (1/4 - (x - 1/2)^2))) - x*ln(x))};
\addplot+[smooth,red,name path=B,domain=0:1,samples=500] {-1/2 * (1/2 * sqrt(abs((sin(deg(5*pi*x))+2) * (1/4 - (x - 1/2)^2))) - x*ln(x))};
\addplot+[red!50] fill between[of=A and B,soft clip={domain=-4:4}];
\draw (axis cs:-1, 0) -- (axis cs:2, 0);
\node[color=red] at (axis cs:.9,.4) {$\mathrm{St}(\Omega)$};
\end{axis}
\end{tikzpicture}
\end{document}
Licensing
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http://creativecommons.org/publicdomain/zero/1.0/deed.en CC0 Creative Commons Zero, Public Domain Dedication false false
English A set Omega together with its Steiner symmetrization