Metasurface base on uneven layered fractal elements for ultra-wideband RCS reduction

A novel metasurface based on uneven layered fractal elements is designed and fabricated for ultra-wideband radar cross section (RCS) reduction in this paper. The proposed metasurface consists of two fractal subwavelength elements with different layer thickness. The reflection phase difference of 180◦ (±37◦) between two unit cells covers an ultra-wide frequency range. Ultra-wideband RCS reduction results from the phase cancellation between two local waves produced by these two unit cells. The diffuse scattering of electromagnetic (EM) waves is caused by the randomized phase distribution, leading to a low monostatic and bistatic RCS simultaneously. This metasurface can achieve -10dB RCS reduction in an ultra-wide frequency range from 6.6 to 23.9 GHz with a ratio bandwidth (fH/fL) of 3.62:1 under normal incidences for both x- and y-polarized waves. Both the simulation and the measurement results are consistent to verify this excellent RCS reduction performance of the proposed metasurface

Health status of the population in Naqu, Tibet and its latent class analysis: a cross-sectional survey

BackgroundThrough a survey and analysis of the population’s present state of health, it is possible to give data support for improving the health status of inhabitants in Naqu, Tibet. Additionally, it is possible to provide specific recommendations for the development of medical and healthcare facilities in Tibet.MethodsThe health scores of the participants were based on their responses to the four main sections of the questionnaire: dietary habits, living habits, health knowledge, and clinical disease history, and the variability of health status among groups with different characteristics was analyzed based on the scores. The four major sections were used to create classes of participants using latent class analysis (LCA). Using logistic regression, the factors influencing the classification of latent classes of health status were investigated.ResultsA total of 995 residents from 10 counties in Naqu were selected as the study subjects. And their demographic characteristics were described. The mean health score of residents after standardization was 81.59 ± 4.68. With the exception of gender, health scores differed between groups by age, education level, different occupations, marital status, and monthly income. The health status in Naqu, Tibet, was divided into two groups (entropy = 0.29, BLRT = 0.001, LMRT = 0.001) defined as the “good health group” and the “general health group.” A monthly income of more than ¥5000 adverse to good health in Naqu, Tibet.DiscussionSingle, well-educated young adults in Naqu, Tibet, have outstanding health. The vast majority of people in Tibet’s Naqu region were in good health. Furthermore, the population’s latent health status was divided into two classes, each with good dietary and living habits choices, low health knowledge, and a history of several clinical diseases. Univariate and multivariate logistic regression analysis showed that monthly income more than ¥5000 was an independent risk factor for poor health status

Disconnection between plant–microbial nutrient limitation across forest biomes

11 páginas.- 7 figuras.- 1 tabla.- 41 referencias.- Additional supporting information can be found online in the Supporting Information section at the end of this article..- Read the free Plain Language Summary for this article on the Journal blog.Nitrogen (N) and phosphorus (P) are essential elements limiting plant–microbial growth in forest ecosystems. However, whether the pattern of plant–microbe nutrient limitation is consistent across forest biomes and the associated potential mechanisms remain largely unclear, limiting us to better understand the biogeochemical processes under future climate change. Here, we investigated patterns of plant–microbial N/P limitation in forests across a wide environmental gradient and biomes in China to explore the divergence of plant–microbial N/P limitation and the driving mechanisms. We revealed that 42.6% of the N/P limitation between plant–microbial communities was disconnected. Patterns in plant–microbial N/P limitations were consistent only for 17.7% of N and 39.7% of P. Geospatially, the inconsistency was more evident at mid-latitudes, where plants were mainly N limited and microbes were mainly P limited. Furthermore, our findings were consistent with the ecological stoichiometry of plants and microbes themselves and their requirements. Whereas plant N and P limitation was more strongly responsive to meteorological conditions and atmospheric deposition, that of microbes was more strongly responsive to soil chemistry, which exacerbated the plant–microbe N and P limitation divergence. Our work identified an important disconnection between plant and microbial N/P limitation, which should be incorporated into future Earth System Model to better predict forest biomes–climate change feedback. Read the free Plain Language Summary for this article on the Journal blog. © 2023 The Authors. Functional Ecology © 2023 British Ecological SocietyNational Natural Science Foundation of China, Grant/Award Number: 42207107; Catalan Government Grant, Grant/Award Number: SGR2017-1005; Fundación Ramón Areces grant, Grant/Award Number: CIVP20A6621; National Key Research and Development Program of China, Grant/Award Number: 2021YFD1901205; Open Fund of Key Laboratory of Agro-Ecological Processes in Subtropical Region, Chinese Academy of Sciences, Grant/Award Number: ISA2021101; Spanish Government, Grant/Award Number: PID2019-110521GB-I00 and PID2020-115770RB-I00; Strategic Priority Research Program of Chinese Academy of Sciences, Grant/Award Number: XDB40020202Peer reviewe

Deciphering microbiomes dozens of meters under our feet and their edaphoclimatic and spatial drivers

24 páginas.- 7 figuras.- referenciasMicrobes inhabiting deep soil layers are known to be different from their counterpart in topsoil yet remain under investigation in terms of their structure, function, and how their diversity is shaped. The microbiome of deep soils (>1 m) is expected to be relatively stable and highly independent from climatic conditions. Much less is known, however, on how these microbial communities vary along climate gradients. Here, we used amplicon sequencing to investigate bacteria, archaea, and fungi along fifteen 18-m depth profiles at 20-50-cm intervals across contrasting aridity conditions in semi-arid forest ecosystems of China's Loess Plateau. Our results showed that bacterial and fungal α diversity and bacterial and archaeal community similarity declined dramatically in topsoil and remained relatively stable in deep soil. Nevertheless, deep soil microbiome still showed the functional potential of N cycling, plant-derived organic matter degradation, resource exchange, and water coordination. The deep soil microbiome had closer taxa-taxa and bacteria-fungi associations and more influence of dispersal limitation than topsoil microbiome. Geographic distance was more influential in deep soil bacteria and archaea than in topsoil. We further showed that aridity was negatively correlated with deep-soil archaeal and fungal richness, archaeal community similarity, relative abundance of plant saprotroph, and bacteria-fungi associations, but increased the relative abundance of aerobic ammonia oxidation, manganese oxidation, and arbuscular mycorrhizal in the deep soils. Root depth, complexity, soil volumetric moisture, and clay play bridging roles in the indirect effects of aridity on microbes in deep soils. Our work indicates that, even microbial communities and nutrient cycling in deep soil are susceptible to changes in water availability, with consequences for understanding the sustainability of dryland ecosystems and the whole-soil in response to aridification. Moreover, we propose that neglecting soil depth may underestimate the role of soil moisture in dryland ecosystems under future climate scenarios.This project was supported by the Joint Key Funds of the National Natural Science Foundation of China (U21A20237), the Strategic Priority Research Program of Chinese Academy of Sciences (XDB40020202). M.D.-B. acknowledges support from TED2021-130908B-C41/AEI/10.13039/501100011033/Unión Europea NextGenerationEU/PRTR and from the Spanish Ministry of Science and Innovation for the I + D + i project PID2020-115813RA-I00 funded by MCIN/AEI/10.13039/501100011033. R.O.H. was funded by the Ramón y Cajal program of the MICINN (RYC-2017 22032), by the R&D Project of the Ministry of Science and Innovation PID2019-106004RA-I00 funded by MCIN/AEI/10.13039/501100011033, and by the European Agricultural Fund for Rural Development (EAFRD) through the “Aid to operational groups of the European Association of Innovation (AEI) in terms of agricultural productivity and sustainability,” Reference: GOPC-CA-20-0001Peer reviewe

Ecoenzymatic stoichiometry reveals widespread soil phosphorus limitation to microbial metabolism across Chinese forests

8 páginas.- 4 figuras.- 57 referencias.- Supplementary information The online version contains supplementary material available at https://doi.org/10.1038/s43247-022-00523-5Forest soils contain a large amount of organic carbon and contribute to terrestrial carbon sequestration. However, we still have a poor understanding of what nutrients limit soil microbial metabolism that drives soil carbon release across the range of boreal to tropical forests. Here we used ecoenzymatic stoichiometry methods to investigate the patterns of microbial nutrient limitations within soil profiles (organic, eluvial and parent material horizons) across 181 forest sites throughout China. Results show that, in 80% of these forests, soil microbes were limited by phosphorus availability. Microbial phosphorus limitation increased with soil depth and from boreal to tropical forests as ecosystems become wetter, warmer, more productive, and is affected by anthropogenic nitrogen deposition. We also observed an unexpected shift in the latitudinal pattern of microbial phosphorus limitation with the lowest phosphorus limitation in the warm temperate zone (41-42 degrees N). Our study highlights the importance of soil phosphorus limitation to restoring forests and predicting their carbon sinks. Phosphorus limitation of soil microbial communities in forests is widespread, increases with soil depth, and is enhanced under wetter and warmer climates and elevated anthropogenic nitrogen deposition, according to ecoenzymatic stoichiometric analyses across 181 forests in China.This study was financially supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB40000000), Funds for International Cooperation and Exchange of National Natural Science Foundation of China (32061123007), National Natural Science Foundation of China (41977031), Program of State Key Laboratory of Loess and Quaternary Geology CAS (SKLLQGZR1803). Contributions from Dr. Chen are funded by H2020 Marie Skłodowska-Curie Actions (No. 839806). M.D.-B. acknowledges support from the Spanish Ministry of Science and Innovation for the I+D+i project PID2020-115813RA-I00 funded by CIN/AEI/10.13039/501100011033. M.D.-B. is also supported by a project of the Fondo Europeo de Desarrollo Regional (FEDER) and the Consejería de Transformación Económica, Industria, Conocimiento y Universidades of the Junta de Andalucía (FEDER Andalucía 2014-2020 Objetivo temático “01–Refuerzo de la investigación, el desarrollo tecnológico y la innovación”) associated with the research project P20_00879 (ANDABIOMA).Peer reviewe

Microbial communities in terrestrial surface soils are not widely limited by carbon

18 páginas.- 5 figuras.- referencias.- Additional supporting information can be found online in the Supporting Information section at the end of this article https://doi.org/10.1111/gcb.16765Microbial communities in soils are generally considered to be limited by carbon (C), which could be a crucial control for basic soil functions and responses of microbial heterotrophic metabolism to climate change. However, global soil microbial C limitation (MCL) has rarely been estimated and is poorly understood. Here, we predicted MCL, defined as limited availability of substrate C relative to nitrogen and/or phosphorus to meet microbial metabolic requirements, based on the thresholds of extracellular enzyme activity across 847 sites (2476 observations) representing global natural ecosystems. Results showed that only about 22% of global sites in terrestrial surface soils show relative C limitation in microbial community. This finding challenges the conventional hypothesis of ubiquitous C limitation for soil microbial metabolism. The limited geographic extent of C limitation in our study was mainly attributed to plant litter, rather than soil organic matter that has been processed by microbes, serving as the dominant C source for microbial acquisition. We also identified a significant latitudinal pattern of predicted MCL with larger C limitation at mid- to high latitudes, whereas this limitation was generally absent in the tropics. Moreover, MCL significantly constrained the rates of soil heterotrophic respiration, suggesting a potentially larger relative increase in respiration at mid- to high latitudes than low latitudes, if climate change increases primary productivity that alleviates MCL at higher latitudes. Our study provides the first global estimates of MCL, advancing our understanding of terrestrial C cycling and microbial metabolic feedback under global climate change.This study was financially supported by the National Natural Science Foundation of China (32101378) and Project funded by the China Postdoctoral Science Foundation (2022M710004)Peer reviewe

Metasurface base on uneven layered fractal elements for ultra-wideband RCS reduction

A novel metasurface based on uneven layered fractal elements is designed and fabricated for ultra-wideband radar cross section (RCS) reduction in this paper. The proposed metasurface consists of two fractal subwavelength elements with different layer thickness. The reflection phase difference of 180◦ (±37◦) between two unit cells covers an ultra-wide frequency range. Ultra-wideband RCS reduction results from the phase cancellation between two local waves produced by these two unit cells. The diffuse scattering of electromagnetic (EM) waves is caused by the randomized phase distribution, leading to a low monostatic and bistatic RCS simultaneously. This metasurface can achieve -10dB RCS reduction in an ultra-wide frequency range from 6.6 to 23.9 GHz with a ratio bandwidth (fH/fL) of 3.62:1 under normal incidences for both x- and y-polarized waves. Both the simulation and the measurement results are consistent to verify this excellent RCS reduction performance of the proposed metasurface

Use of montmorillonite-enriched siltstone for improving water condition and plant growth in sandy soil

Revegetation in arid and semi-arid regions is restricted by soil water shortage. Improvement of sandy soil properties, especially for soil water related properties, is therefore vital for successful revegetation. In this study, montmorillonite-enriched siltstone (MS), a type of fine particle soil material, was used to improve sandy soil in a field experiment with four volume proportions: 0% (M-0%), 25% (M-25%), 75% (M-75%), and 100% (M-100%) of MS, which was then planted with alfalfa (Medicago sativa) for 3 years. The objective was to investigate the improvement effect of MS on the physical properties of sandy soil and its support for plant growth. The results showed that the addition of MS significantly increased the soil physical quality (SPQ) indicators, such as available water capacity (AWC), which increased from 7.39% (M-0%) to 10.18% (M-100%), while hydraulic conductivity (Ks) decreased by 34.1% (M-25%) and 57.5% (M-75%), and bulk soil air capacity (ACB) decreased by 12.6% (M-25%) and 39.4% (M-75%). These results were mainly related to the high content of fine particles in MS, such as montmorillonite, a 2:1 clay mineral. The average profile soil water content (SWC) increased from 9.20% to 14.08% (M-25%) and 24.62% (M-75%). The temporal stability of SWC was also significantly increased by MS addition, while drainage was significantly decreased. Both above-ground biomass (ABG) and water use efficiency (WUE) increased by approximately two times in M-25% and M-75% in 2015 and five times in M-25% and M-75% in 2016. This result verified the positive effect of MS addition on sandy soil properties. However, more than 75% MS addition (such as M-100%) in sandy soil decreased ACB to less than 15% and decreased ABG by 75.3% compared with that of M-75%. This study gives a new strategy for improving sandy soil using local finer materials with a high content of montmorillonite. Considering the improvement effects and engineering cost, a 25% volume proportion of MS was recommended

Randomized study of singledose, three-day, and seven-day treatment of cystitis in

We evaluated the following five treatment regimens for acute cystitis in nonpregnant women: cefadroxil, 1,000 mg single-dose; cefadroxil, 500 mg twice a day for three days; cefadroxil, 500 mg twice a day for seven days; trimethoprim-sulfamethoxazole (TMP-SMZ), 320-1,600 mg single-dose, and TMP-SMZ, 160-800 mg twice a day for three days. At four week