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Abstract: Forest structural diversity was estimated for an ecological province in the north-central region of the United States of America using data for nearly 350 000 trees observed on >12 [...]

The classical zero-shifting technique is generalized to cover extraction of complex transmission zeros (TZs) in the form of fourth-order LC sections whereby the j[omega]-and [alpha]-axis TZs appear as special cases. Using this approach, bandpass filters can be synthesized in direct coupled resonator forms by pole placement instead of designing them through low-pass prototypes. By using circuit transformations, the resulting direct coupled resonator filter circuits can then be transformed into a variety of cross-coupled forms like a fully cross-coupled form or cascaded N-tuplet form. It is shown that one or more finite j[omega]-axis, [alpha]-axis, or complex TZs can be extracted as direct coupled resonator circuit blocks, which can be converted into cross-coupled triplets, quadruplets, or other N-tuplets of resonators. In particular, it is shown that a cascaded quadruplet section can be used to realize a complex TZ quadruplet [s.sub.i] = [+ or -] [[sigma].sub.i] [+ or] j[omega]i, as well as two pairs of j[omega]-axis TZs, [s.sub.i] = [+ or -] j[[omega].sub.i] and [s.sub.k] = [+ or -] j[omega].sub.k]. Index Terms--Cross-coupled, filters, linear phase, synthesis.

Forests in tropical and sub-tropical countries face severe pressures due to a combination of poverty and environment degradation. To be effective, measures to protect these forests must therefore consider both economic and ecological dimensions synergistically. The purpose of this paper was to synthesize our long-term work (1994-2015) on a Ginkgo (Ginkgo biloba L.) agroforestry system and demonstrate its potential for achieving both goals, and discuss its wider application in tropical and sub-tropical countries. The performance of various ecological, economic, and social indicators was compared among five Ginkgo agroforestry systems. Two additional indicators, Harmony Degree (HD) and Development Degree (DD), were also used to show the integrated performance of these indicators. Ginkgo-Wheat-Peanut (G+W+P) and Ginkgo-Rapeseed-Peanut (G+R+P) are the best systems when compared to pure and mixed Ginkgo plantations, or pure agricultural crops. Results demonstrate that it is possible to achieve both economic development and environmental protection through implementation of sustainable agroforestry systems in sub-tropical regions. [ABSTRACT FROM AUTHOR]