%% Calculate significant beta
e = [zeros(size(Q_xy,1)-size(B,2), size(B,2)); eye(size(B,2))];
V_beta0 = e'*(Q_xy\e);

% mean_e = mean(e);
mean_e = mean(B);

sd_e = [mean_e - sqrt(diag(V_beta0))'; mean_e; mean_e + sqrt(diag(V_beta0))']