Added multi-shot dynamic rat kidney data

sample_data/Rat Kidneys Dynamic MRS/demo_dynamic_mrs_multishot_fit.m

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+% fit slab dynamic MRS data from repeated injections ("shots") in a single rat
+% as an example, does a kPL fit only (ignores alanine, bicarb)
+
+% Data and studies described in
+% Hu, Simon, Peder E Z Larson, Mark Vancriekinge, Andrew M Leach, Ilwoo Park, Christine Leon,  et al. 
+% “Rapid Sequential Injections of Hyperpolarized [1-¹³C]pyruvate in Vivo Using a Sub-Kelvin, Multi-Sample DNP Polarizer.” 
+% Magn Reson Imaging 31, no. 4 (May 2013): 490–96. 
+% https://doi.org/10.1016/j.mri.2012.09.002.
+
+clear all
+plot_flag = 1;
+int_range = 25;
+
+for ratnum = 1:4;
+
+    switch ratnum
+        case 1
+            Nshots = 4;
+            lac_center = 970;
+            pyr_hyd_center = 1020;
+            ala_center = 1056;
+            pyr_center = 1130;
+            bicarb_center = 1262;
+        case 2
+            Nshots = 3;
+            lac_center = 967;
+            pyr_hyd_center = 1018;
+            ala_center = 1053;
+            pyr_center = 1128;
+            bicarb_center = 1260;
+        case 3
+            Nshots = 3;
+            lac_center = 968;
+            pyr_hyd_center = 1019;
+            ala_center = 1054;
+            pyr_center = 1129;
+            bicarb_center = 1260;
+        case 4
+            Nshots = 3;
+
+            lac_center = 876;
+            pyr_hyd_center = 927;
+            ala_center = 963;
+            pyr_center = 1037;
+            bicarb_center = 1168;
+
+        case 5
+            Nshots = 3;
+            lac_center = 875;
+            pyr_hyd_center = 926;
+            ala_center = 961;
+            pyr_center = 1036;
+            bicarb_center = 1168;
+    end
+
+
+    clear params_fixed params_est params_fit kPL
+    R1P_est = 1/30; R1L_est = 1/25;  kPL_est = 0.01;
+    params_fixed.R1P = R1P_est; params_fixed.R1L = R1L_est;
+    params_est.kPL = kPL_est;
+
+    for n = 1:Nshots
+        load(sprintf('rat%d/shot%d',ratnum,n));
+        pyr = real(sum(spectra_dynamic(pyr_center+[-int_range:int_range],:),1));
+        lac = real(sum(spectra_dynamic(lac_center+[-int_range:int_range],:),1));
+        [params_fit Sfit] = fit_kPL([pyr;lac] , TR, repmat(flip, [2 length(pyr)]), params_fixed, params_est, [], plot_flag);
+        kPL(n) = params_fit.kPL;
+    end
+
+    disp(['Rat #' int2str(ratnum) ' kPL fits: ' num2str(kPL) ' 1/s'])
+end