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Size-asymmetric root competition in deep,nutrient-poor soil

Journal of Plant Ecology 2019年第1期12卷 78-88页

作者： Camilla Ruø Rasmussen Anne Nygaard Weisbach kristian Thorup-Kristensen Jacob Weiner Department of Plant and Environmental Sciences University of CopenhagenHøjbakkegaard Allé13Taastrup DK-2630Denmark Department of Plant and Environmental Sciences University of CopenhagenThorvaldsensvej 40Frederiksberg DK-1871Denmark

Aims There is much evidence that plant competition below ground is size symmetric,*** competing plants share contested resources in proportion to their *** researchers have hypothesized that a patchy distribution of soil nutrients could result in size-asymmetric root *** tested this *** In a greenhouse experiment,Triticum aestivum(wheat)individ-uals of different initial sizes were grown alone or with below-ground competition from one neighbour,in 1 m tall,narrow containers in a nitrogen-poor field soil with(i)no added nitro-gen,(ii)nitrogen fertilizer mixed into the upper 50 cm,and(iii)the same amount of fertilizer mixed into a 20-30 cm deep *** measured total leaf length throughout the experiment,and above-ground biomass and nitrogen concentration at *** also measured root depth and frequency over time in a subset of *** Findings Competing plants were half the size of non-competing plants,meaning that root competition was very *** competition was size-asym-metric to some degree in all soil *** larger than the target plant showed a greater per-unit-size effect on target growth than neighbours smaller than the *** variation increased over time for competing individuals,but decreased for non-competing *** to expectations,the presence of a high-nutrient patch reduced the strength and size asymmetry of competition *** asym-metry in poor,deep soils may result from directionality in resource interception as roots compete for limited nutrients by growing deeper into soil layers that have not yet been *** competition can be size asymmetric,but not to the same degree as competition for light.

关键词： below-ground competition resource pre-emption size inequality size advantage Triticum aestivum

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Intercropping effect on root growth and nitrogen uptake at different nitrogen levels

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Journal of Plant Ecology 2015年第4期8卷 380-389页

作者： Javier Ramirez-Garcia Helle J.Martens Miguel Quemada kristian Thorup-Kristensen Dpto.Producción Vegetal:Fitotecnia ETSI AgrónomosAvd.Complutense s/nUniversidad Politécnica de Madrid28040 MadridSpain Department of Plant and Environmental Sciences University of CopenhagenHøjbakkegaards Alle 13DK-2630TaastrupDenmark

Aims Intercropping legumes and non-legumes may affect the root growth of both components in the mixture,and the non-legume is known to be strongly favored by increasing nitrogen(N)*** knowledge of how root systems affect the growth of the individual species is useful for understanding the interactions in intercrops as well as for planning cover cropping *** aim of this work was(i)to determine if different levels of N in the topsoil influence root depth(rD)and intensity of barley and vetch as sole crops or as an inter-cropped mixture and(ii)to test if the choice of a mixture or the N availability in the topsoil will influence the N uptake by deep *** In this study,we combined rhizotron studies with root extraction and species identification by microscopy with studies of growth,N uptake and 15N uptake from deeper soil layers,for studying the root interactions of root growth and N foraging for barley(Hordeum vul-gare l.)and vetch(Vicia sativa l.),frequently grown in mixtures as cover crops.N was added at 0(N0),50(N1)and 150(N2)kg N ha−*** roots discrimination relying on the anatomical and morphologi-cal differences observed between dicots and monocots proved to be a reliable method providing valuable data for the *** Findingsthe intercrop and the barley attained slightly higher root intensity(rI)and rD than the vetch,with values around 150 crosses m−1 and 1.4 m,respectively,compared to 50 crosses m−1 and 0.9 m for the *** deep soil layers,intercropping showed slightly larger rI values compared to the sole-cropped *** barley and the intercropping had larger root length density(r D)values(200-600 m m−3)than the vetch(25-130)at 0.8-1.2 m *** topsoil N supply did not show a clear effect on the rI,rD or r D;however,increasing topsoil N favored the proliferation of vetch roots in the intercropping at deep soil layers,with the barley:vetch root ratio ranging from 25 at N0 to 5 at *** N uptake of the barley was

关键词： grasses legumes cover crops crop mixture root discrimination labeled N

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Mass effect,aneurysms and flow diverters:Is the pipeline embolization device the Lone Virtuoso?Commentary on‘Pipeline embolization device for intracranial aneurysms presenting with mass effect:a large Chinese cohort’by Zhao et al

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Stroke & Vascular Neurology 2024年第4期9卷 457-458页

作者： Alexander Sirakov Georgi Vladev Kristina Sirakova kristian Ninov Krasimir Minkin Vasil Karakostov Stanimir Sirakov Interventional Radiology University Hospital St Ivan RilskiSofiaBulgaria Medical University of Sofia SofiaBulgaria

In the treatment of symptomatic intracranial aneurysms,the study by Zhao et al stands as a notable addition to the growing body of literature.^(1) Their investigation regarding the Pipeline Embolisation Device’s(PED,Covi-dien/Medtronic,Irvine,California,USA)effi-cacy in alleviating mass effect offers valuable insights that further contribute to the evolving landscape of neurointerventional *** applaud the authors for their dedicated efforts in tackling an essential facet of aneu-rysm *** with studies involving extensive cohorts is always enlight-ening,as they ignite discussions and open avenues for fresh research opportunities.

关键词： aneurysm Irvine intracranial

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Two-dimensional ferroelectrics from high throughput computational screening

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npj Computational Materials 2023年第1期9卷 1901-1911页

作者： Mads Kruse Urko Petralanda Morten N.Gjerding Karsten W.Jacobsen kristian S.Thygesen Thomas Olsen CAMD Department of PhysicsTechnical University of DenmarkDK-2800 Kongens LyngbyDenmark

We report a high throughput computational search for two-dimensional ferroelectric *** starting point is 252 pyroelectric materials from the computational 2D materials database(C2DB)and from these we identify 63 *** particular we find 49 materials with in-plane polarization,8 materials with out-of-plane polarization and 6 materials with coupled in-plane and out-of-plane *** of the known 2D ferroelectrics are recovered by the screening and the far majority of the predicted ferroelectrics are known as bulk van der Waals bonded compounds,which makes them accessible by direct *** roughly 25%of the materials we find a metastable state in the non-polar structure,which may imply a first order transition to the polar ***,we list the magnetic pyroelectrics extracted from the C2DB and focus on the case of VAgP2Se6,which exhibits a three-state switchable polarization vector that is strongly coupled to the magnetic excitation spectrum.

关键词： materials polarization plane

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Exploring and machine learning structural instabilities in 2D materials

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npj Computational Materials 2023年第1期9卷 2016-2025页

作者： Simone Manti Mark Kamper Svendsen Nikolaj R.Knøsgaard Peder M.Lyngby kristian S.Thygesen CAMD Computational Atomic-Scale Materials DesignDepartment of PhysicsTechnical University of Denmark2800 Kgs.LyngbyDenmark Center for Nanostructured Graphene(CNG) Department of PhysicsTechnical University of DenmarkDK-2800 Kongens LyngbyDenmark

We address the problem of predicting the zero-temperature dynamical stability (DS) of a periodic crystal without computing its fullphonon band structure. Here we report the evidence that DS can be inferred with good reliability from the phonon frequencies atthe center and boundary of the Brillouin zone (BZ). This analysis represents a validation of the DS test employed by theComputational 2D Materials Database (C2DB). For 137 dynamically unstable 2D crystals, we displace the atoms along an unstablemode and relax the structure. This procedure yields a dynamically stable crystal in 49 cases. The elementary properties of these newstructures are characterized using the C2DB workflow, and it is found that their properties can differ significantly from those of theoriginal unstable crystals, e.g., band gaps are opened by 0.3 eV on average. All the crystal structures and properties are available inthe C2DB. Finally, we train a classification model on the DS data for 3295 2D materials in the C2DB using a representation encodingthe electronic structure of the crystal. We obtain an excellent receiver operating characteristic (ROC) curve with an area under thecurve (AUC) of 0.90, showing that the classification model can drastically reduce computational efforts in high-throughput studies.

关键词： structure unstable structural

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Cellulose synthesis in land plants

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Molecular Plant 2023年第7期16卷 206-231页

作者： Gustav B.Pedersen Leonard Blaschek kristian E.H.Frandsen Lise C.Noack Staffan Persson Copenhagen Plant Science Center(CPSC) Department of Plant&Environmental SciencesUniversity of CopenhagenThorvaldsensvej 401871Frederiksberg CDenmark Joint International Research Laboratory of Metabolic&Developmental Sciences State Key Laboratory of Hybrid RiceSJTU-University of Adelaide Joint Centre for Agriculture and HealthSchool of Life Sciences and BiotechnologyShanghai Jiao Tong UniversityShanghaiChina

All plant cells are surrounded by a cell wall that provides cohesion,protection,and a means of directional growth to *** microfibrils contribute the main biomechanical scaffold for most of these *** biosynthesis of cellulose,which typically is the most prominent constituent of the cell wall and therefore Earth’s most abundant biopolymer,is finely attuned to developmental and environmental *** understanding of the machinery that catalyzes and regulates cellulose biosynthesis has substantially improved due to recent technological advances in,for example,structural biology and ***,we provide a comprehensive overview of the structure,function,and regulation of the cellulose synthesis machinery and its regulatory *** aim to highlight important knowledge gaps in the field,and outline emerging approaches that promise a means to close those gaps.

关键词： plant cell wall cellulose microfibrils cellulose synthases membrane proteins cytoskeleton protein interaction

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Beyond the RPA and GW methods with adiabatic xc-kernels for accurate ground state and quasiparticle energies

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npj Computational Materials 2019年第1期5卷 202-224页

作者： Thomas Olsen Christopher E.Patrick Jefferson E.Bates Adrienn Ruzsinszky kristian S.Thygesen Computational Atomic-Scale Materials Design(CAMD) Department of PhysicsTechnical University of DenmarkKongens LyngbyDenmark Department of Physics University of WarwickCoventry CV47ALUK A.R.Smith Department of Chemistry and Fermentation Sciences Appalachian State UniversityBooneNC 28607USA Department of Physics Temple UniversityPhiladelphiaPA 19122USA Center for Nanostructured Graphene(CNG) Department of PhysicsTechnical University of DenmarkKongens LyngbyDenmark

We review the theory and application of adiabatic exchange–correlation(xc)-kernels for ab initio calculations of ground state energies and quasiparticle excitations within the frameworks of the adiabatic connection fluctuation dissipation theorem and Hedin’s equations,*** different xc-kernels,which are all rooted in the homogeneous electron gas,are introduced but hereafter we focus on the specific class of renormalized adiabatic kernels,in particular the rALDA and *** kernels drastically improve the description of short-range correlations as compared to the random phase approximation(RPA),resulting in significantly better correlation *** effect greatly reduces the reliance on error cancellations,which is essential in RPA,and systematically improves covalent bond energies while preserving the good performance of the RPA for dispersive *** quasiparticle energies,the xc-kernels account for vertex corrections that are missing in the GW *** this context,we show that the short-range correlations mainly correct the absolute band positions while the band gap is less affected in agreement with the known good performance of GW for the *** renormalized xc-kernels offer a rigorous extension of the RPA and GW methods with clear improvements in terms of accuracy at little extra computational cost.

关键词： adiabatic kernels quasi

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Which Central and Eastern European country has the greatest potential for housing market recovery？

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Journal of Modern Accounting and Auditing 2010年第11期6卷 25-33页

作者： kristian Kahre Tallinn School of Economics and Business Administration Tallinn University of Technology Tallinn 10125 Estonia

This paper is concentrated on analyzing the CEE （Central and Eastern European） countries housing and lending market development in 2002-2009. These countries experienced real estate boom and bust phases during that time and the aim of this paper is to understand which of these countries have the greatest potential for housing market recovery. The study has conducted comparable analysis of these countries and their real estate and lending market. The data was collected from central banks, national statistic offices and real estate companies. The results suggest that countries with higher housing debt had stronger real estate booms and the current bust-cycle has caused much steeper decline in prices. This paper attempts to look at the CEE housing markets from the developer＇s or investor＇s point of view and may be useful for banks and other financial institutions which are related to housing market and lending.

关键词： housing price-to-income ratio housing boom Central and Eastern Europe

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A Comparative Study of the Effect of Gold Seed Particle Preparation Method on Nanowire Growth

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Nano Research 2010年第7期3卷 506-519页

作者： Maria E.Messing Karla Hillerich Jessica Bolinsson kristian Storm Jonas Johansson Kimberly A.Dick Knut Deppert Solid State Physics Lund UniversityBox 118S-22100 LundSweden Polymer&Materials Chemistry Lund UniversityBox 124S-22100 LundSweden

Highly controlled particle-assisted growth of semiconductor nanowires has been performed for many years,and a number of novel nanowire-based devices have been *** control of the epitaxial growth is required to optimize the performance of devices,and gold seed particles are known to provide the most controlled *** nanowire growth from gold particles generated and deposited by various different methods has been reported,but no investigation has yet been performed to compare the effects of gold particle generation and deposition methods on nanowire *** this article we present a direct comparative study of the effect of the gold particle creation and deposition methods on nanowire growth characteristics and nanowire crystal structure,and investigate the limitations of the different generation and deposition methods used.

关键词： Nanowire growth nanoparticles gold epitaxy electron microscopy

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Shift current photovoltaic efficiency of 2D materials

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npj Computational Materials 2023年第1期9卷 1991-1999页

作者： Mikkel Ohm Sauer Alireza Taghizadeh Urko Petralanda Martin Ovesen kristian Sommer Thygesen Thomas Olsen Horia Cornean Thomas Garm Pedersen Department of Materials and Production Aalborg University9220 AalborgØstDenmark Department of Mathematical Sciences Aalborg University9220 AalborgØstDenmark Center for Nanostructured Graphene(CNG) 9220 AalborgØstDenmark Computational Atomic-scale Materials Design(CAMD) Department of PhysicsTechnical University of Denmark2800 Kgs.LyngbyDenmark Department of Physics University of the Basque Country(UPV/EHU)Apartado 644Bilbao 48080Spain Center for Nanostructured Graphene(CNG) 2800 Kgs.LyngbyDenmark

Shift current photovoltaic devices are potential candidates for future cheap,sustainable,and efficient electricity *** the present work,we calculate the solar-generated shift current and efficiencies in 326 different 2D materials obtained from the computational database *** apply,as metrics,the efficiencies of monolayer and multilayer *** monolayer efficiencies are generally found to be low,while the multilayer efficiencies of infinite stacks show great ***,the out-of-plane shift current response is considered,and material candidates for efficient out-of-plane shift current devices are *** the screened materials,MXY Janus and MX_(2) transition metal dichalchogenides(TMDs)constitute a prominent subset,with chromium based MXY Janus TMDs holding particular ***,in order to explain the band gap dependence of the PV efficiency,a simple gapped graphene model with a variable band gap is established and related to the calculated efficiencies.

关键词： Shift database multilayer

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