Prediction error aggregation behaviour for remote sensing augmented forest inventory approaches

In this study we investigated the behaviour of aggregate prediction errors in a forest inventory augmented with multispectral Airborne Laser Scanning and airborne imagery. We compared an Area-Based Approach (ABA), Edge-tree corrected ABA (EABA) and Individual Tree Detection (ITD). The study used 109 large 30 × 30 m sample plots, which were divided into four 15 × 15 m subplots. Four different levels of aggregation were examined: all four subplots (quartet), two diagonal subplots (diagonal), two edge-adjacent subplots (adjacent) and subplots without aggregation. We noted that the errors at aggregated levels depend on the selected predictor variables, and therefore, this effect was studied by repeating the variable selection 200 times. At the subplot level, EABA provided the lowest mean of root mean square error ($\overline{\mathrm{RMSE}}$) values of 200 repetitions for total stem volume (EABA 21.1 percent, ABA 23.5 percent, ITD 26.2 percent). EABA also fared the best for diagonal and adjacent aggregation ($\overline{\mathrm{RMSE}}$: 17.6 percent, 17.4 percent), followed by ABA ($\overline{\mathrm{RMSE}}$: 19.3 percent, 18.2 percent) and ITD ($\overline{\mathrm{RMSE}}$: 21.8, 21.9 percent). Adjacent subplot errors of ABA were less correlated than errors of diagonal subplots, which resulted also in clearly lower RMSEs for adjacent subplots. This appears to result from edge tree effects, where omission and commission errors cancel for trees leaning from one subplot into the other. The best aggregate performance was achieved at the quartet level, as expected from fundamental properties of variance. ABA and EABA had similar RMSEs at the quartet level ($\overline{\mathrm{RMSE}}$ 15.5 and 15.3 percent), with poorer ITD performance ($\overline{\mathrm{RMSE}}$ 19.4 percent).

Ground and Excited Electronic Energy Surfaces of the MnS4 Cluster in ZnS:Mn2+

Gaussian-based Self Consistent Field (SCF) MOs are obtained at various nuclear geometries for the MnS4 cluster in the external potential of cubic ZnS. Electronic relaxation and d-shell electron correlation effects are then included. For Td symmetry, quartet d-d excitation energies calculated as functions of R(Mn-S) qualitatively resemble the simple CF diagram. While separations between successive quartet levels agree closely with experiment, the threshold is about 0.5 eV high; much of this discrepancy is removed by including additional correlation effects from charge-transfer states. Large Jahn-Teller (JT) splittings of 4T1 and 4T2 levels are found with D2d distortion. Difficulty in accurately evaluating force constants interferes with predicting the corresponding deformations and stabilization energies. Estimates, encorporating the observed Stokes'; shift and JT stabilization energy, are that R(Mn-S) decreases by ∼0.1 Å and the S-Mn-S dihedral angle increases by 7sim;8°, in the lowest quartet level.

Hyperfine structure and isotope shift of the 6s6p 2 4 P ½ level of Tl I

The h. f. s. splittings and isotope shifts have been measured for the transition 6s 2 6p 2 P 0 ½ –6s 6p 2 4 P ½ in Tl 203 , Tl 205 . These are the largest splittings occurring in the levels of Tl I. The results agree in order of magnitude with splittings and shifts to be expected theoretically. The quartet level perturbs the n = 10 member of the 6s 2 ns 2 S ½ series, which consequently acquires a large splitting and a measurable shift.