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\begin{center}
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\put(105,360){\circle{45}}                % gamma0 circle
\put(105,360){\makebox(0,0){\Large $\gamma_0$}}
\put(180,360){\circle{45}}               % gamma1 circle
\put(180,360){\makebox(0,0){\Large $\gamma_1$}}
\put(255,360){\circle{45}}               % phi circle
\put(255,360){\makebox(0,0){\Large $\phi$}}
\put(180,270){\circle{45}}                % alpha circle
\put(180,270){\makebox(0,0){\Large $\alpha$}}
\put(120.3,345.3){\line(1,-1){55}}      % arrow from gamma1 to alpha
\put(180,339){\line(0,-1){48}}       % arrow from gamma2 to alpha
\put(240,345){\line(-1,-1){55}}    % arrow from phi to alpha
\put(270,270){\circle{45}}                % beta circle
\put(270,270){\makebox(0,0){\Large $\beta$}}
\put(225,180){\circle{45}}                % s circle
\put(225,180){\makebox(0,0){\Large S}}
\put(191,253){\line(1,-2){27}}           % arrow from alpha to S
\put(259,252){\line(-1,-2){27}}          % arrow from beta to S
\put(225,90){\circle{45}}                % mu circle
\put(225,90){\makebox(0,0){\Large Y}}
\put(225,159){\line(0,-1){48}}        % arrow from S to Y
\put(150,180){\circle{45}}                % H circle
\put(150,180){\makebox(0,0){\Large H}}
\put(300,180){\circle{45}}                % lambda circle
\put(300,180){\makebox(0,0){\Large $\lambda$}}
\put(370,180){\circle{45}}                % C1 circle
\put(370,180){\makebox(0,0){\Large $C_0$}}
\put(150,90){\circle{45}}                % sigma^2 circle
\put(150,90){\makebox(0,0){\Large $\sigma^2$}}
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\put(285,165){\line(-3,-4){45}}         % arrow from lambda to Y
\put(358,164){\line(-3,-2){113}}       % arrow from I to Y
\put(171,90){\line(1,0){33}}         % arrow from sigma^2 to Y
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