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Exploring the factors affecting carbon and nutrient concentrations in tree biomass components in natural forests,forest plantations and short rotation forestry

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Forest Ecosystems 2018年第4期5卷 498-515页

作者： Roque Rodriguez-Soalleiro Cristina Eimil-Fraga Esteban Gomez-Garda Juan Daniel Garcia-Villabrille Alberto Rojo-Alboreca Fernando Munoz Nerea Oliveira Hortensia Sixto cesar perez-cruzado Sustainable Forest Management Unit (UXFS) Department of Plant Production and Engineering ProjectsUniversidade de Santiago de Compostela (USC)Rua Benigno LedoCampus Terra27002 LugoSpain Centro de Investigacion Forestal de Lourian Xunta de Galicia.Carretera de Marin km 3.536153 PontevedraSpain Sustainable Forest Management Unit (UXFS) Department of Agroforestry EngineeringUniversldade de Santiago de Compostela (USC)LugoSpain Universidad de Concepcion Facultad de Ciencias ForestalesVlctona631 ConcepcionChile Forest Systems and Resources Department Centre for Forest ResearchINIACrta. de la Coruna km 7.528040MadridSpain

Background: Coupling biomass models with nutrient concentrations can provide sound estimations of carbon and nutrient contents, enabling the improvement of carbon and nutrient balance in forest ecosystems. Although nutrient concentrations are often assumed to be constant for some species and specific tree components, at least in mature stands,the concentrations usually vary with age, site index and even with tree density. The main objective of this study was to evaluate the sources of variation in nutrient concentrations in biomass compartments usually removed during harvesting operations, covering a range of species and management conditions: semi-natural forest, conventional forest plantations and short rotation forestry(SRF). Five species(Betula pubescens, Quercus robur, Eucalyptus globulus, Eucalyptus nitens and Populus spp.) and 14 genotypes were considered. A total of 430 trees were sampled in 61 plots to obtain 6 biomass components:leaves, twigs, thin branches, thick branches, bark and wood. Aboveground leafless biomass was pooled together *** concentrations of C, N, K, P, Ca, Mg, S, Fe, Mn, Cu, Zn and B were measured and the total biomass of each sampled tree and plot were determined. The data were analysed using boosted regression trees and conventional ***: The main sources of variation in nutrient concentrations were biomass component > > genotype(species) ≈ age >tree diameter. The concentrations of Ca, Mg and K were most strongly affected by genotype and age. The concentrations of P, K, Ca, Mg, S and Cu in the wood component decreased with age, whereas C concentrations increased, with a trend to reach 50% in the older trees. In the SRF, interamerican poplar and P. trichocarpa genotypes were comparatively more efficient in terms of Ca and K nutrient assimilation index(NAI)(+65-85%) than eucalypts, mainly because leafless biomass can be removed. In the conventional eucalypt plantations(rotation 15 years), debarking the wood at logg

关键词： Nutrient removal Biomass crops Poplar genotypes Eucolyptus Oak Birch Plantation sustainability

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In vitro germination and shoot proliferation of the threatened species Cinchona officinalis L(Rubiaceae).

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Journal of Forestry Research 2016年第6期27卷 1229-1236页

作者： Rosa Armijos-Gonzalez cesar perez-Ruiz Departamento de Ciencias Naturales Universidad Tecnica Particular de LojaCP 1101 608 LojaEcuador Departamento de Biotecnologia y Biologia Vegetal E.T.S.Ingenieros AgronomosUniversidad Politecnica de MadridCP 728040 MadridSpain

Cinchona officinalis （Rubiaceae） is an endemic species of the Loja Valley in southern Ecuador with medicinal uses. Because of over-exploitation in the nine- teenth century and more recent disturbances to its ecosystem, C. officinalis populations are threatened. Currently, natural regeneration of the populations is low, despite its high plant regeneration and seed formation capacity. In the present study, an efficient protocol for germination, shoot proliferation and plantlets regeneration was developed for this species. Phenolic content and germination rate of C. officinalis seeds were compared with a control species, C. pubescens. Nodal segments from seedlings of C. officinalis were cultured on Gamborg medium supplemented with different combinations of plant growth regulators. Because the phenol content is high in C. officinalis, the phenolic should be removed with hydrogen peroxide or water washes to stimulate germination. Shoots and callus developed from nodal segments within 45 days using most of the tested combinations of plant growth regulators. The best rates of shoot proliferation, callus formation and adventitious buds were obtained in medium supplemented with 5.0 mg L^-1 6-benzyl-aminopurine and 3.0 mg L^-1 indole- 3-butyfic acid.

关键词： Callus Cinchona officinalis Germination Phenols Rubiaceae Shoot

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FANET and MANET, a Support and Composition Relationship

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Computers, Materials & Continua 2025年第2期82卷 1699-1732页

作者： Carlos Andrés Tavera Romero Jesús Hamilton Ortiz Luis Carlos Rodríguez Timaná Fernando Vélez Varela Andrés Hernando Aristizábal Montufar Javier Gamboa-cruzado COMBA R&D Laboratory Faculty of EngineeringUniversidad Santiago de CaliCali76001Colombia Development Department Closemobile R&D Telecommunications LSMadrid28070Spain GIEIAM Research Group Faculty of EngineeringUniversidad Santiago de CaliCali76001Colombia Faculty of Engineering Universidad LibreCali760031Colombia Faculty of Systems and Informatics Engineering Universidad Nacional Mayor de San MarcosLima15001Perú

This study investigates the design and implementation of Flying Ad Hoc Networks(FANETs),a network architec-ture inspired by the Mobile Ad Hoc Network(MANET)model,specifically tailored to support unmanned aerial vehicles(UAVs).As UAVs increasingly contribute to diverse fields,from surveillance to delivery,FANETs have emerged as essential in ensuring stable,dynamic communication channels among drones in *** research adopts a dual approach,combining rigorous theoretical analysis with detailed practical simulations to assess the performance,adaptability,and efficiency of FANETs in varying *** findings emphasize the ability of FANETs to manage network congestion effectively in densely populated areas,a critical feature for maintaining reliable communications in complex ***,FANETs demonstrate high potential to support critical applications,such as emergency response,disaster management,and public safety operations,where quick and coordinated action is *** study also underscores the importance of establishing a hierarchical structure among nodes within the network,which allows for more efficient data exchange and helps optimize the overall network *** this work,significant insights are offered into the design principles that can enhance UAV communication networks,providing a foundation for the development of more resilient,scalable,and efficient technological *** advancements could accelerate the deployment of UAVs across a variety of sectors,including logistics,agriculture,environmental monitoring,and *** such,this study not only contributes to the field of ad hoc networking but also holds potential for transformative impacts across industries where UAVs play an increasingly central role,promoting greater integration and operational success.

关键词： Ad hoc FANET MANET network UAV

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A review of GaN RF devices and power amplifiers for 5G communication applications

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Fundamental Research 2025年第1期5卷 315-331页

作者： Lu, Hao Zhang, Meng Yang, Ling Hou, Bin Martinez, Rafael perez Mi, Minhan Du, Jiale Deng, Longge Wu, Mei Chowdhury, Srabanti Ma, Xiaohua Hao, Yue School of Microelectronics Xidian University Xi'an 710071 China Department of Electrical Engineering Stanford University Stanford 94305 CA United States

In the emerging 5G and beyond 5G (B5G) era, the spotlight is sharply focused on the power amplifier, a critical component with stringent specification requirements that dictates the performance of the transmitter. The gallium nitride (GaN) device, with its superior inherent properties, is surfacing as a front-runner for power amplifier applications. The increasing demand for high frequency, high linearity, and cost-effective GaN power amplifiers is driven by anticipated traffic surges and the need for extensive 5G deployment. This paper offers a thorough review and future perspective on research developments in RF GaN device technology. It encompasses critical issues in advanced device and circuit technology, with a focus on high frequency, high linearity, cost-effective GaN-on-Si high electron mobility transistors (HEMTs), and compact modeling. This work aims to serve as a guide for the utilization of GaN HEMTs in 5G communication applications. © 2023

关键词： 5G Gallium nitride GaN-on-Si HEMTs High frequency High linearity

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奇妙的萤火虫魅力十足又对科学深具价值的萤火虫,未来却充满变数

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空中英语教室(高级版.彭蒙惠英语) 2025年第3期 32-34,49,50页

作者： Adriana perez 不详

对于许多在密西西比河以东长大的人来说,黄色的闪烁光芒点缀着如梦如幻的童年回忆。在新英格兰长大的人叫它们萤火虫,但从美国中西部到南方的人们称它们为“闪烁虫”(译注1)。不管它们在不同区域叫什么名字,它们都是温暖夏夜的常客。

关键词：新英格兰萤火虫美国中西部密西西比河童年回忆闪烁

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Occasional Tillage in a Field Established under Conservation Agriculture for Tomato Cropping

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Agricultural Sciences 2025年第1期16卷 31-47页

作者： Roberto Botelho Ferraz Branco Bruno cesar Ananias Andréia Cristina Silva Hirata Humberto Sampaio de Araújo Jane Maria de Carvalho Silveira Agronomic Institute So Paulo Agency of Agribusiness Technology (IAC/APTA) Centre of Horticulture Ribeiro Preto Brazil Syngenta Crop Protection So Paulo Brazil So Paulo Agency of Agribusiness Technology (APTA) Presidente Prudente Brazil So Paulo Agency of Agribusiness Technology (APTA) Andradina Brazil Agronomic Institute So Paulo Agency of Agribusiness Technology (IAC/APTA) Centre of Agricultural Biosystems and Post Harvest Campinas Brazil

The Conservation Agriculture (CA) is a current concept drives to save natural resources for agricultural production based on the minimum soil disturbance or no-tillage, crop rotation and permanent maintenance of straw on soil surface. The increasing in soil density is a problem to achieve great copping yield under CA, so occasional one-time tillage is considered as an alternative to continuous no-tillage. In this way, this experiment was carried out to compare occasional tillage and no-tillage interacting with cover crops in a field established under conservation agriculture. Thus, the experimental treatments were set up by two tillage methods, conventional tillage and no-tillage and two cover crops, white lupin and millet setting in a randomized blocks with split plot design with four replications. The traits evaluated in the research were soil fertility, soil resistance to penetration, soil moisture and tomato agronomic performance. No-tillage was more efficient to preserve soil moisture;however soil fertility, soil resistance to penetration and tomato yield were favored by conventional tillage. Regarding to cover crops white lupin increased the soil K concentration and enhanced the tomato growth. Although occasional tillage had better performance to the soil fertility and tomato yield, we highlighted that CA is the better way to increase soil health and soil and water conservation along the time leading to so desired regenerative agriculture.

关键词： No Tillage Crop Rotation Cover Crops Solanum lycopersicum L.

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A Theoretical Model of the Water Vapor Diffusion through the Surface of Cloud Droplets

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Journal of Earth Science and Engineering 2015年第8期5卷 520-523页

作者： Raul cesar perez Lihando Ceds. Department of Subjects Basics National Technological University Regional Mendoza Faculty Rodriguez 257.Mendoza Argentina

In order to understand better the dynamics of formation, growth and evaporation process of the cloud drops, it had developed a mathematical and physics model, using the equation of the vapor diffusion law get cross its surface, taken into consideration that it has a spherical form. When the spherical drop is formed, its time of live will depend on its radio value a; so, on the one hand, if the a value is bigger than critical radio value, then the drop growth because the condensation process win to the evaporation process, on the other hand, if the a value is less than critical radio value, then the cloud drop will be evaporated. To case the drop growth, the condensation process to the vapor diffusion gets cross its surface government the phenomenal dynamical. This important process is theoretically modeling in order to get a bigger understanding to design more efficient method of modifying them in a benefit way.

关键词： Drop diffusion model water vapor.

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Study of the Influence of Critical Radius on the Cloud Drops Formation in the Seeding Operations

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Journal of Environmental Science and Engineering(A) 2012年第5期1卷 616-619页

作者： Rauil cesar perez Department of Civil Engineering National Technology University Mendoza 5500 Argentina

In the seeding operations in order to mitigate the climatic changes or to intervene beneficently on the precipitations process, it is very important to know the roll of the critical radius size of the cloud drops formation and its posterior evolution. In the seeding operations programs, the fundament is to determinate the critical radius in order to obtain efficient results. So, it must consider （a） the critical radius size necessary in order to get the better results; （b） the atmospheric conditions that determine it. In order to get a methodology to calculate the critical radius in each atmospheric condition, the present work has been developed. And with them, it can estimate the nuclei size necessary in order to assure good seeding. The authors had obtained approximate values that were good enough to the goals.

关键词： Critical radius precipitation modification cloud seeding.

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China's Global Shipping Connectivity:Internal and External Dynamics in the Contemporary Era(1890–2016)

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Chinese Geographical Science 2018年第2期28卷 202-216页

作者： cesar DUCRUET WANG Liehui French National Center for Scientific Research UMR 8504 Geographie-citesParis F-75006France The Center for Modern Chinese City Studies East China Normal UniversityShanghai 200062China School of Urban and Regional Science East China Normal UniversityShanghai 200241China

China's global shipping connectivity had been somewhat overlooked as the bulk of related studies predominantly focused on the throughput volume of its own port cities. This article tackles such lacunae by providing a relational perspective based on the extraction of vessel movement archives from the Lloyd's List corpus. Two complementary analyses are proposed: long-term dynamics with all ships included(1890–2008) and medium-term dynamics focusing on container flows(1978–2016). Each analysis examines China's maritime connectivity in various ways and on different spatial scales, from the global to the local, in terms of concentration, vulnerability, and expansion. The main results underline the influence of technological, economic, and political factors on the changing distribution of connectivity internally and externally. In particular, China has managed to reduce its dependence upon external transit hubs, to increase the internal connectivity of its own port system, and to strengthen its dominance towards an increasing number of foreign nodes and trade partners through the maritime network.

关键词： China connectivity maritime network port system vessel movements

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Calorimetry is not color-blind. Molecular insights on association processes in surfactant-polymer mixtures derived from calorimetric experiments

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Science China Chemistry 2011年第12期54卷 2024-2027页

作者： LOH Watson BRINATTI cesar Institute of Chemistry Universidade Estadual de Campinas(UNICAMP)

This comment will review and discuss recent results obtained with the use of calorimetry in assessing molecular information from complex phenomena such as association in surfactant/polymer mixtures. These examples were selected to support the view that it is possible to ally the great sensitivity of modem calorimeters with carefully planned experiments and, sometimes, ancillary techniques in order to derive detailed information on molecular interactions.

关键词： calorimetry polymer-surfatant interaction self-assembly

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