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Investigating space allocation patterns of plant secondary xylem along a latitudinal gradient is useful to evaluate structure-function tradeoffs in woody angiosperm xylem. An anatomical dataset including 700 woody angiosperm species across China was compiled together with latitudinal and climate data for each species. The relative tissue fractions of vessels, fibers, and parenchyma (including ray and axial parenchyma) in xylem were analyzed to determine the effect of latitudinal differences and phylogeny on anatomical variation. The analyses revealed a trade-off between vessel and non-vessel fraction across latitude, with tissue fraction trade-offs mainly occurring between vessels and fibers, and between fibers and total parenchyma. Among 13 climate variables, thermal indices generally had greater explanatory power than moisture indices in bi-variate models for all cell types, while mean annual temperature, mean temperature of the coldest month, and annual actual evapotranspiration were included in the top multi-variate models explaining variance of different tissue fractions. Phylogeny and climate together explained 57–73% of the total variation in xylem space occupancy, with phylogeny alone accounting for over 50% of the variation. These results contribute to our knowledge of wood structure-function and are relevant to better understand forest response to climate change.

In this paper, a dual-polarized frequency selective rasorber (FSR) with two independent transmission windows and three absorption bands is designed and characterized. The proposed FSR is composed of the resistive sheet and the bandpass frequency selective surface (FSS), which are separated by the air spacer. At the top resistive sheet, two concentric modified square loops with different lengths are inserted into the square loop with four lumped-resistor-loaded legs, which provides two independent transmission windows. The bottom bandpass FSS, consisting of the combination of the square slot and the four-leg arrow shaped slot, is adopted to realize the same transmission bands as the upper resistive sheet. Performance of the proposed FSR is investigated via its equivalent circuit model and full-wave simulations. The simulated results exhibit dual-band frequency response, which has two independent transmission windows within three absorption bands. The two pass-bands operate at 8.5GHz and 13GHz with insertion loss of 0.31dB and 0.48dB, respectively. And the three absorption bands are in the range of 4. , respectively. Also, the band with reflection coefficient lower than -10dB covers from 4.2 GHz to 19.6GHz and the fractional bandwidth is up to 129.4%. Furthermore, prototype of the FSR is fabricated and measured. Good agreements between the measured and the simulated results can be observed.

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