Woody plant species richness and productivity relationship in a subtropical forest: The predominant role of common species.

A long-standing key issue for examining the relationships between biodiversity and ecosystem functioning (BEF), such as forest productivity, is whether ecosystem functions are influenced by the total number of species or the properties of a few key species. Compared with controlled ecosystem experiments, the BEF relationships in secondary forest remain unclear, as do the effects of common species richness and rare species richness on the variation in ecosystem functions. To address this issue, we conducted field surveys at five sampling sites (1 ha each) with subtropical secondary evergreen broad-leaved forest vegetation. We found (1) a positive correlation between species richness and standing aboveground biomass (AGB); (2) that common species were primarily responsible for the distribution patterns of species abundance and dominance; although they accounted for approximately 25% of the total species richness on average, they represented 86-91% of species abundance and 88-97% of species dominance; and (3) that common species richness could explain much more of the variation in AGB than total species richness (common species plus rare species) at both the site and plot scales. Because rare species and common species were not equivalent in their ability to predict productivity in the biodiversity-ecosystem productivity model, redundant information should be eliminated to obtain more accurate results. Our study suggested that woody plant species richness and productivity relationship in subtropical forest ecosystem can be explained and predicted by a few common species.

Anti-resonant fiber with high-resistivity silicon for THz wave transmission.

A novel anti-resonant fiber for low-loss terahertz waveguides is proposed and analyzed. The terahertz fiber uses high-resistivity silicon as the bulk material and nine nested double-layer concentric circular tubes in the cladding to reduce propagation losses. The effects of the geometric parameters on the propagation characteristics are analyzed by the finite element method. The result indicates that an ultra-low total loss of 4.9×10-4 d B/m is achieved at f=1T H z. The low-loss propagation window is 0.48 THz ranging from 0.6 to 1.4 THz. In addition, the influence of mechanical bending on the propagation loss is investigated and the bending loss can be maintained at less than 7.3×10-3 d B/m at f=1T H z even if the bending radius is larger than 60 cm. The properties of this anti-resonant fiber are significantly superior to those of previously reported structures and the fiber thus has large commercial potential.

Surface plasmon resonance sensor composed of a D-type photonic crystal fiber with a three-layer coating.

A surface plasmon resonance sensor composed of photonic crystal fibers (PCF-SPR) with an A u-T i O 2-A u triple layer is designed for refractive index (RI) sensing and analyzed theoretically by the finite element method. The sensor exhibits enhanced resonance coupling between the core mode and surface plasmon polariton (SPP) mode as well as better sensitivity than the structure with a single gold coating. Furthermore, the A u-T i O 2-A u tri-layer structure narrows the linewidth of the loss spectrum and improves the figure of merit (FOM). In the analyte RI range of 1.30-1.42, the maximum wavelength sensitivity is 20,300 nm/RIU, resolution is 4.93×10-6, amplitude sensitivity is 6427R I U -1, and FOM is 559R I U -1. The results provide insights into the design of high-performance PCF-SPR sensors.

Highly sensitive dual-core photonic quasicrystal fiber methane sensor based on surface plasmon resonance.

A highly sensitive dual-core photonic quasicrystal fiber methane sensor based on surface plasmon resonance is designed and analyzed. In this sensor, cryptophane E is doped with polysiloxane and Ag and used as the sensitive film and plasma medium, respectively, for sensitive detection of methane. The influence of the structural parameters on the sensor properties is analyzed by the finite element method. The optimized dual-quasi-D-shape structure has excellent methane-sensing properties such as maximum and average wavelength sensitivities of 14 and 10.98 nm/%, respectively, in the methane concentration range of 0%-3.5%. The sensitivity is better than that of similar sensors reported previously.

Identifying Excessive Intake of Oil and Salt to Prevent and Control Hypertension: A Latent Class Analysis.

Introduction: To identify health hazard behaviors and provide a basis for targeted management and intervention for patients with hypertension, we classified their health-related behaviors. Methods: A multi-stage random sampling method was used to conduct an on-site questionnaire survey among residents aged ≥15 years in a certain urban area of Taiyuan City, Shanxi Province, China. A latent class analysis was used to classify the lifestyle behaviors of patients with hypertension. The lifestyle behavior characteristics of different types of patients with hypertension and their awareness of hypertension were assessed. Results: The prevalence of hypertension in Taiyuan City was 19.5%. Patients with hypertension were classified into three clusters according to their lifestyle patterns: smoking and drinking (13.35%), excessive edible oil and salt intake (68.27%), and healthy behavior (18.38%). Comparing the three latent classes of lifestyle, the distribution of age, sex, marital status, and education level was different (P < 0.05). The awareness of hypertension and the rate of control among the three classes were also different (P < 0.05). Conclusion: The lifestyle behaviors of patients with hypertension have evident classification characteristics. Approximately two-thirds of the patients with hypertension have an excessive intake of oil and salt. Therefore, targeted and precise intervention measures should be taken to control the intake of oil and salt in this cohort.

High-sensitivity methane sensor composed of photonic quasi-crystal fiber based on surface plasmon resonance.

A photonic quasi-crystal fiber (PQF) methane sensor based on surface plasmon resonance (SPR) is designed and described. The double-side polished six-fold photonic quasi-crystal fiber coated with a silver film produces enhanced SPR effects and sensitivity. A nanostructured thin film with cryptophane-E-doped polysiloxane is deposited on silver as the methane-sensitive surface layer and to mitigate oxidation of silver. The sensor is analyzed and optimized numerically by the full-vector finite element method. For methane concentrations in the range of 0% to 3.5%, the maximum sensitivity of the sensor is 8 nm/%, and the average sensitivity is 6.643 nm/%. Compared to traditional gas sensors, this sensor provides accurate sensing of methane besides offering advantages such as the low cost, miniaturized size, online monitoring, and immunity to electromagnetic field interference.

Enhancement of unidirectional forward scattering and suppression of backward scattering in hollow silicon nanoblocks.

Manipulating the light scattering direction and enhancing directivity are important research areas in integrated nanophotonic devices. Herein, a novel, to the best of our knowledge, nanoantenna composed of hollow silicon nanoblocks is designed to allow directional emission manipulation. In this device, forward scattering is enhanced and backward scattering is restrained substantially in the visible region. Owing to electric dipole resonance and magnetic dipole resonance in this nanoantenna, Kerker's type conditions are satisfied, and the directionality of forward scattering GFB reaches 44.6 dB, indicating good characteristics in manipulating the light scattering direction.

Surface plasmon resonance sensor based on U-shaped photonic quasi-crystal fiber.

A high-sensitivity surface plasmon resonance (SPR) sensor is designed and analyzed numerically. The sensor is constructed on the eightfold U-shaped photonic quasi-crystal fiber (PQF) and coated with indium tin oxide (ITO). The coupling between the core mode and surface plasmon polariton mode is enhanced due to shortening of the distance between the core and the ITO layer, so that the PQF-SPR sensor exhibits high refractive index (RI) sensitivity in the near-infrared region. The maximum wavelength sensitivity and the corresponding resolution of this sensor are 42,000 nm/RIU and 2.38×10-6RIU, respectively. The average wavelength sensitivity is 12,750 nm/RIU in the refractive index range of 1.306-1.386. This advanced sensor is suitable for the determination of RIs in the near-infrared region.

High-sensitivity SPR sensor based on the eightfold eccentric core PQF with locally coated indium tin oxide.

A highly sensitive surface plasmon resonance (SPR) sensor comprising an eccentric core photonic quasi-crystal fiber (PQF) coated with indium tin oxide is designed and numerically analyzed. The novel, to the best of our knowledge, structure with an eccentric core layout and local coating not only strengthens coupling between the core mode and surface plasmon polariton mode but also provides higher refractive index sensitivity in the near-infrared region. Analysis based on the finite element method to assess the performance of the sensor and optimize the structural parameters reveals that the maximum wavelength sensitivity and resolution are 96667 nm/RIU and 1.034×10-6RIU in the sensing range between 1.380 and 1.413, respectively. Meanwhile, the average sensitivity is enhanced to 25458 nm/RIU. The sensor is expected to have broad applications in environmental monitoring, biochemical sensing, food safety testing, and related applications due to the ultrahigh sensitivity and resolution.

Surface plasmon resonance sensor based on eccentric core photonic quasi-crystal fiber with indium tin oxide.

A sensing device composed of an eccentric core photonic quasi-crystal fiber based on surface plasmon resonance is designed using indium tin oxide (ITO) as the sensitive materials. The ITO film is deposited on the outside surface of the fiber to excite plasmonic interactions and facilitate refractive index (RI) detection. This eccentric core structure makes the evanescent field coupled effectively with analyte to achieve higher sensitivity. The influence of RI and structural parameters of different analytes on sensor performance was calculated by the finite-element method. In the analyte RI range between 1.33 and 1.39, the wavelength sensitivity reaches 21,100 nm/RIU, and the average sensitivity of 8750 nm/RIU is achieved at a resolution of 4.739×10-6 RIU. The sensor has large potential in the detection of unknown RI analytes in the near-infrared region.

Spatially destabilising effect of woody plant diversity on forest productivity in a subtropical mountain forest.

We used geographically weighted regression to investigate the relationship between biodiversity and the spatial stability of forest productivity (SSFP) in a subtropical mountain forest. We examined the effect of elevation on this relationship and on its spatial non-stationarity. We found that higher woody plant diversity reduced SSPF. Higher woody plant diversity strengthened the asynchrony of species responses to spatial heterogeneity of forest habitats, which contributed to SSFP, but reduced two factors that enhanced SSFP: species dominance and the spatial stability of the dominant species. The percentage of variation in SSFP explained by diversity measures was highest for the Shannon-Wiener index, lowest for functional dispersion, and intermediate for species richness. The correlations of woody plant diversity with SSFP became stronger with elevation and varied among plots, indicating that the spatial non-stationarity existed in the biodiversity-SSFP relationship. These correlations became weaker in most cases after controlling for elevation. Our results suggest that in the subtropical mountain forest higher woody plant diversity has a spatially destabilising effect on forest productivity, particularly at higher elevations.

Topography-associated thermal gradient predicts warming effects on woody plant structural diversity in a subtropical forest.

Understanding global warming effects on forest ecosystems will help policy-makers and forest managers design forest management and biodiversity conservation strategies. We examined the change in woody plant structural diversity in response to topography-associated thermal gradients in a subtropical forest with diverse abundance patterns. We found that energy distribution in a warming trend across slopes had significant effects on woody plant structural diversity. Except for total basal area of the adult trees, plant structural diversity significantly decreased with the increase of heat load. Heat load is significantly and negatively correlated with number of stems, number of species, and the number of stems of the most abundant species (Nmax) for seedlings, saplings, and individuals of all sizes. For the adult trees, heat load is significantly and positively correlated with number of stems and Nmax, and negatively but not significantly with number of species, indicating that large trees may not be as sensitive as seedlings and saplings to warming. Partial correlation analysis, having controlled for elevation, strengthened those relations in most cases. Our results reveal that warming will increase community productivity by enhancing the growth of large trees, but decrease species diversity and inhibit the regeneration of tree seedlings and saplings.