44,955 research outputs found
Refilling of embolized vessels in young stems of Laurus nobilis L.: do we need a new paradigm?
No full textHydraulic limits on tree performance: Transpiration, carbon gain and growth of trees
No full textAn overview of the relationship between plant gas exchange, the potential hydraulic gradient, the size of the plant and its hydraulic conductance is presented. Key references are used to exemplify arguments of whole-plant optimality and to explain the origin and development of the dominant paradigm for interpreting the nature of water use and growth in plants.Resource /Energy Economics and Policy,
Hydraulic conductance of peach trees grafted on rootstocks with differing size-controlling potentials
No full textThe objective of this study was to evaluate the hydraulic conductance in various components of peach trees grown on rootstocks with contrasting size-controlling potentials. The experiment was conducted on `Crimson Lady' peach trees grafted onto two rootstocks: a semi-dwarfing rootstock, K-146-44 (P. salicina.3.P. persica hybrid) and a vigorous rootstock, Nemaguard (seed-propagated Prunus persica.3.P. davidiana hybrid). Hydraulic conductance of leaves, stems, trunk, graft union, and root system was measured in the scion/rootstocks with a high-pressure flow meter. Total leaf area and dry-matter partitioning into main tree components were also determined. The above and below ground portions of trees grown on Nemaguard rootstock were 393% and 299% larger, respectively, than trees grown on K-146-44 rootstock. Whether trees were grafted on Nemaguard or K-146-44, the root system accounted for most of the resistance to water flow through the tree. When hydraulic conductance was expressed per unit leaf area, trees on K-146-44 rootstock had significantly lower root conductance than trees on Nemaguard rootstock. Rootstocks had no effect on hydraulic conductance through the scion or the graft union. Trees on K-146-44 also partitioned relatively more dry matter to roots and leaves and less to stems than trees on Nemaguard. The results suggest that high root resistance plays a central role in the dwarfing mechanism induced by the size-controlling rootstock
Plasticity of functional traits of tree of heaven is higher in exotic than in native habitats
No full textKey message: Novel features related to turgor loss adjustment and higher ability to modulate leaf-construction costs could improve A. altissima fitness in its invaded range. Abstract: Phenotypic plasticity has been recently proposed to play an important role in invasion process. More precisely, phenotypic plasticity of alien invasive species could be higher in their exotic rather than native habitat, probably because of the release from biotic or abiotic constraints. In this paper, several plant functional traits were analysed on Ailanthus altissima (Mill.) Swingle, a highly invasive species in Europe, aiming at providing a comparison among key functional traits measured on individuals growing in their native habitat and to test if values of functional traits and their related plasticity are higher in exotic habitats. Our analysis pinpointed that variability of functional traits in the native habitat was mainly driven by different irradiance, temperature and evaporative demand of the studied sites, in accordance to the traits trade-offs in the Leaf Economic Spectrum. Physiological traits related to drought tolerance were different between native and exotic habitats. In the native one, A. altissima relied on osmoregulation processes to adjust leaf turgor loss point (Ψ tlp ), as the osmotic potential at full turgor (π 0 ) were lower in drier sites. In the exotic habitat, individuals in drier sites had similar π 0 but lower wall elasticity (ε), suggesting that leaves had thinner cell walls. Moreover, plasticity in specific leaf area and ε were higher in the exotic habitat. The novel features related to Ψ tlp adjustment and the higher plasticity in traits related to leaf-construction costs could increase A. altissima fitness in response to different environmental conditions in its invasive range
Settling of finite-size particles in isotropically forced, homogeneous turbulence: interface-resolved simulations
No full textWe have simulated the gravity-induced settling of finite-size particles in a turbulent background flow which is forced in a statistically-stationary fashion. The simulations are accurately resolving the solid-fluid interface with the aid of an immersed boundary technique [1]. The parameters of the simulation are (apart from background turbulence) identical to those of reference [2], where particle clustering was observed at a Galileo number of 178 and a solid volume fraction of 0.005. In the present case, it is found that a relative turbulence intensity of 0.24 leads to the disappearance of the clusters; as a consequence, the increase in average particle settling velocity found in [2] also vanishes. [1] M. Uhlmann. An immersed boundary method with direct forcing for the simulation of particulate flows. J. Comput. Phys., 209(2):448–476, 2005. [2] M. Uhlmann and T. Doychev. Sedimentation of a dilute suspension of rigid spheres at intermediate Galileo numbers: the effect of clustering upon the particle motion. J. Fluid Mech., 752:310–348, 2014
Mesophilic-hydrothermal-thermophilic (M-H-T) digestion of green corn straw
No full textMesophilic-hydrothermal (80-160 degrees C, 30 min)-thermophilic (M-H-T) digestion and control tests of mesophilic (M), thermophilic (T), hydrothermal-mesophilic (H-M), and mesophilic-thermophilic digestion (M-T) of green corn straw were conducted for a 20-day fermentation period. The results indicate that M-H-T is an efficient method to improve methane production. A maximum methane yield of 371.74 mL/g volatile solid was obtained by the M (3 days)-H (140 degrees C)-T (17 days) process, which was 20.44%, 16.55%, 31.44%, and 14.31% higher than the yields of the M, T, 140-M, and M-T processes. The enhanced methane production was attributed to (1) the improved hemicellulose degradation and lignin disorganization; (2) prevention of the degradation of soluble sugar, easily hydrolyzed hemicellulose and cellulose into furfural and methylfurfural; and (3) lack of formation of Maillard reaction products during initial hydrothermal treatment. (C) 2015 Elsevier Ltd. All rights reserved
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
The maternal immune system during pregnancy and its influence on fetal development
No full textThe maternal immune system plays a critical role in the establishment, maintenance, and completion of a healthy pregnancy. However, the specific mechanisms utilized to achieve these goals are not well understood. Various cells and molecules of the immune system are key players in the development and function of the placenta and the fetus. Effector cells of the immune system act to promote and yet limit placental development. The T helper 1 (Th1)/T helper 2 (Th2) immune shift during pregnancy is well established. A fine balance between proinflammatory and anti-inflammatory influences is required. We herein review the evidence regarding maternal tolerance of fetal tissues and the underlying cell-mediated immune and humoral (hormones and cytokines) mechanisms. We also note the many unanswered questions in our understanding of these mechanisms. In addition, we summarize the clinical manifestations of an altered maternal immune system during pregnancy related to susceptibility to common viral, bacterial, and parasitic infections, as well as to autoimmune diseases.Peer reviewe
Erosie door open taludbekledingen. Samenvattend verslag + Bijlage A t/m D
No full textOpen taludbekledingen die bestaan uit in verband geplaatste betonblokken met gaten, bieden de mogelijkheid vegetatie te doen groeien, waardoor mogelijk een milieuvriendelijke oever kan worden verkregen. In het pioniersstadium van de vegetatie is het evenwel ongewenst dat de gatvulling uitspoelt. Teneinde de relatie tussen waterbeweging en erosie van de gatvulling vast te stellen, is door de Dienst Weg- en Waterbouwkunde van Rijkswaterstaat per brief d.d. 16 maart 1987 (kenmerk WB 570), opdracht verleend aan het Waterloopkundig Laboratorium tot het uitvoeren van onderzoek naar de erosie door open taludbekledingen. Het doel van het onderzoek is het ontwikkelen van ontwerprichtlijnen voor taludbekledingen met gaten die groter zijn dan de zand- of filterkorrels eronder. Hiertoe dient de kritieke waterbeweging bij een oever- of dijkbekleding te worden vastgesteld, waarbij nog toelaatbare erosie is te verwachten. De toelaatbare erosie mag daarbij maximaal gelijk zijn aan de hoeveelheid sediment in de gaten. Filter- of basismateriaal gelegen onder de elementen mag dus niet uitspoelen. Bij oeverbekledingen waar vegetatie een rol moet gaan spelen, is de toelaatbare erosie kleiner, dat wil zeggen in de gaten dient sediment achter te blijven.Steenzettingen - TAW/EN
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