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986 results for “exchange”
Data from: Gas exchange and leaf anatomy of a C3-CAM hybrid, Yucca gloriosa (Asparagaceae)
While the majority of plants use the typical C3 carbon metabolic pathway, ~6% of angiosperms have adapted to carbon limitation as a result of water stress by employing a modified form of photosynthesis known as Crassulacean acid metabolism (CAM). CAM plants concentrate carbon in the cells by temporally separating atmospheric carbon acquisition from fixation into carbohydrates. CAM has been studied for decades, but the evolutionary progression from C3 to CAM remains obscure. In order to better understand the morphological and physiological characteristics associated with CAM photosynthesis, phenotypic variation was assessed in Yucca aloifolia, a CAM species, Yucca filamentosa, a C3 species, and Yucca gloriosa, a hybrid species derived from these two yuccas exhibiting intermediate C3–CAM characteristics. Gas exchange, titratable leaf acidity, and leaf anatomical traits of all three species were assayed in a common garden under well-watered and drought-stressed conditions. Yucca gloriosa showed intermediate phenotypes for nearly all traits measured, including the ability to acquire carbon at night. Using the variation found among individuals of all three species, correlations between traits were assessed to better understand how leaf anatomy and CAM physiology are related. Yucca gloriosa may be constrained by a number of traits which prevent it from using CAM to as high a degree as Y. aloifolia. The intermediate nature of Y. gloriosa makes it a promising system in which to study the evolution of CAM.
Data from: New insights into carbon acquisition and exchanges within the coral-dinoflagellate symbiosis under NH4+ and NO3- supply
Anthropogenic nutrient enrichment affects the biogeochemical cycles and nutrient stoichiometry of coastal ecosystems and is often associated with coral reef decline. However, the mechanisms by which dissolved inorganic nutrients, and especially nitrogen forms (ammonium versus nitrate) can disturb the association between corals and their symbiotic algae are subject to controversial debate. Here, we investigated the coral response to varying N : P ratios, with nitrate or ammonium as a nitrogen source. We showed significant differences in the carbon acquisition by the symbionts and its allocation within the symbiosis according to nutrient abundance, type and stoichiometry. In particular, under low phosphate concentration (0.05 µM), a 3 µM nitrate enrichment induced a significant decrease in carbon fixation rate and low values of carbon translocation, compared with control conditions (N : P = 0.5 : 0.05), while these processes were significantly enhanced when nitrate was replaced by ammonium. A combined enrichment in ammonium and phosphorus (N : P = 3 : 1) induced a shift in nutrient allocation to the symbionts, at the detriment of the host. Altogether, these results shed light into the effect of nutrient enrichment on reef corals. More broadly, they improve our understanding of the consequences of nutrient loading on reef ecosystems, which is urgently required to refine risk management strategies.
Data from: Leafing patterns and leaf exchange strategies of a cerrado woody community
The deciduousness of tropical trees and communities depend on ecosystems characteristics such as plant species diversity, and strength of the dry season. Based on seven-years of phenological observations we provide the first long-term description of leafing patterns of a woody cerrado community, aiming to investigate: (1) the leaf exchange strategies considering the inter-annual variation on the degree of deciduousness of individuals and species and quantify the community deciduousness; (2) the relationship between inter-annual patterns of leaf fall and leaf flush according to the species` leaf exchange strategies and climate; (3) the onset of cerrado growing season and its relation to climate seasonality. To detect seasonality and leafing onset we applied circular statistics and to understand the relationships between environmental predictors and leaf exchange strategies, we used generalized additive models. From 106 species observed, we classified 69 as deciduous (26 species), semi-deciduous (25) or evergreen (18) and defined the studied cerrado as a semi-deciduous vegetation. Leaf phenology was markedly seasonal, and similar among years. Leaf fall peaked in the dry season, and leaf flush in the dry-to-wet transition. Leaf fall patterns related to temperature and leaf flush to day length and rainfall. Semi-deciduous and deciduous species were more constrained by climate then the evergreen ones. The cerrado growing season started in the dry-to-wet season transition. Inter-annual variations in rainfall and temperature affected the individuals' and, consequently, species' degree of deciduousness, highlighting individual and species variability, and suggesting that cerrado leafing patterns is likely susceptible to future climate change scenarios.
Data from: Kin discrimination and outer membrane exchange in Myxococcus xanthus: a comparative analysis among natural isolates
Genetically similar cells of the soil bacterium Myxococcus xanthus cooperate at multiple social behaviours, including motility and multicellular development. Another social interaction in this species is outer-membrane exchange (OME), a behaviour of unknown primary benefit in which cells displaying closely related variants of the outer-membrane protein TraA transiently fuse and exchange membrane contents. Functionally incompatible TraA variants do not mediate OME, which led to the proposal that TraA incompatibilities determine patterns of intercellular cooperation in nature, but how this might occur remains unclear. Using natural isolates from a centimetre-scale patch of soil, we analyse patterns of TraA diversity and ask whether relatedness at TraA is causally related to patterns of kin discrimination in the form of both colony-merger incompatibilities (CMIs) and inter-strain antagonisms. A large proportion of predicted TraA functional diversity documented among global isolates is contained within the cm-scale population. We find evidence of balancing selection on the PA14-portion of TraA and extensive transfer of traA alleles across genomic backgrounds. CMIs are shown to be common among strains identical at TraA, suggesting that CMI kin discrimination is not generally caused by TraA dissimilarity. Finally, it has been proposed that inter-strain antagonisms might be caused by OME-mediated toxin transfer. However, we find that most strain pairs exhibiting strong antagonisms are predicted to be incapable of OME due to TraA dissimilarity. Overall, our results suggest that documented patterns of kin discrimination in a defined natural population of M. xanthus are not causally related to the degree of TraA relatedness among interactants.
Data from: Localizing FST outliers on a QTL map reveals evidence for large genomic regions of reduced gene exchange during speciation-with-gene-flow
Populations that maintain phenotypic divergence in sympatry typically show a mosaic pattern of genomic divergence, requiring a corresponding mosaic of genomic isolation (reduced gene flow). However, mechanisms that could produce the genomic isolation required for divergence-with-gene-flow have barely been explored, apart from the traditional localized effects of selection and reduced recombination near centromeres or inversions. By localizing FST outliers from a genome scan of wild pea aphid host races on a Quantitative Trait Locus (QTL) map of key traits, we test the hypothesis that between-population recombination and gene exchange are reduced over large 'divergence hitchhiking' (DH) regions. As expected under divergence hitchhiking, our map confirms that QTL and divergent markers cluster together in multiple large genomic regions. Under divergence hitchhiking, the nonoutlier markers within these regions should show signs of reduced gene exchange relative to nonoutlier markers in genomic regions where ongoing gene flow is expected. We use this predicted difference among nonoutliers to perform a critical test of divergence hitchhiking. Results show that nonoutlier markers within clusters of FST outliers and QTL resolve the genetic population structure of the two host races nearly as well as the outliers themselves, while nonoutliers outside DH regions reveal no population structure, as expected if they experience more gene flow. These results provide clear evidence for divergence hitchhiking, a mechanism that may dramatically facilitate the process of speciation-with-gene-flow. They also show the power of integrating genome scans with genetic analyses of the phenotypic traits involved in local adaptation and population divergence.
Data from: Evolutionary inferences from the analysis of exchangeability
Evolutionary inferences are usually based on statistical models that compare mean genotypes and phenotypes (or their frequencies) among populations. An alternative is to use the actual distribution of genotypes and phenotypes to infer the "exchangeability" of individuals among populations. We illustrate this approach by using discriminant functions on principal components to classify individuals among paired lake and stream populations of threespine stickleback in each of six independent watersheds. Classification based on neutral and non-neutral microsatellite markers was highest to the population of origin and next-highest to populations in the same watershed. These patterns are consistent with the influence of historical contingency (separate colonization of each watershed) and subsequent gene flow (within but not between watersheds). In comparison to this low genetic exchangeability, ecological (diet) and morphological (trophic and armor traits) exchangeability was relatively high – particularly among populations from similar habitats. These patterns reflect the role of natural selection in driving parallel changes adaptive changes when independent populations colonize similar habitats. Importantly, however, substantial non-parallelism was also evident. Our results show that analyses based on exchangeability can confirm inferences based on statistical analyses of means or frequencies, while also refining insights into the drivers of – and constraints on – evolutionary diversification.
Data from: Dynamic pore structure evolution of the ion adsorbed rare earth ore during the ion exchange process
<p><span>During the leaching process of the ion adsorbed rare earth ore, the pore structure evolution of the ore body plays a vital role in the seepage of the leaching solution. To investigate the evolution of the pore structure during the leaching process, experiments have been carried out with remodeled rare earth ore samples based on physical characteristics of in-situ ores. The seepage rate difference between deionized water leaching solution and 2% NH<sub>4</sub>Cl leaching solution during the active leaching period are analyzed. The porosity and the dynamic pore size evolution of pore structures in the ore body are discussed. Results indicate that along with ion exchange between the rare earth ore and the leaching solution, the porosity of the sample remains constant and the pore structure shows a decreasing trend in the first part and an increasing trend in the second part. Specifically, during the ion exchange process, the number of minimal pores (0~5μm), small pores (5~10μm), and medium pores (10~25μm) increases significantly and the number of medium-large pores (25~60μm), large pores (60~120μm), and mega pores (>120μm) decreases dramatically. Along with the completion of the ion exchange process, the evolution of porous structure shows an opposite trend. The mechanism study reveals that the evolution of pore structure is induced by the difference of ionic strength in the leaching solution during the ion exchange process, where the rare earth ore microparticles will be absorbed or desorbed on to the solid phase.</span></p>
Data from: Reconciling extremely strong barriers with high levels of gene exchange in annual sunflowers
In several cases, estimates of gene flow between species appears to be higher than predicted given the strength of interspecific barriers. However, as far as we are aware, detailed measurements of reproductive isolation have not previously been compared with a coalescent-based assessment of gene flow. Here, we contrast these two measures in two species of sunflower, Helianthus annuus and Helianthus petiolaris. We quantified the total reproductive barrier strength between these species by compounding the contributions of the following prezygotic and postzygotic barriers: ecogeographic isolation, reproductive asynchrony, immigrant inviability, pollen competition, hybrid seed formation, hybrid seed germination, hybrid pollen fertility, and hybrid seed set. The estimated probabilities that a reproductively successful hybrid is produced: range from 10^-4 to 10^-6 depending on the direction of the cross and the degree of independence among reproductive barriers. Population genetic estimates of gene flow estimated between these sunflower species (N_e m = 0.34-0.76) are due mainly to their large effective population sizes (N_e >10^6). The interspecific migration rate (m) is very small (<10^-7) and an order of magnitude lower than that expected based on our reproductive barrier strength estimates. Thus, even high levels of reproductive isolation (> 0.999) may produce genomic mosaics.
Data from: High tolerance of tropical sapling growth and gas exchange to moderate warming
The effects of global warming on tropical forest growth and carbon storage are uncertain. While observations on canopy trees indicate negative correlations between temperature and growth, some seedling studies suggest the opposite. These contrasting results may reflect ontogenetic differences in temperature responses, or differences between the performance of potted plants under controlled conditions and plants under more variable conditions in the field. To try to bridge the gap between highly-controlled experiments on small seedlings and field observations on canopy trees we conducted two sets of outdoor experiments on saplings up to 2.5 m tall; one set to study the effects of night warming, and another set on the effects of day warming. To test the hypothesis that night warming would reduce growth in tropical saplings through stimulation of respiration, we grew the early-successional species Ochroma pyramidale in large 380-liter soil containers under ambient nighttime temperature and ambient +4.5°C. To test the hypothesis that day warming would reduce growth by reducing photosynthesis we compared plants in multi-species and single-species mesocosms rooted in the ground under ambient and passively warmed daytime conditions. In all experiments we monitored growth and measured foliar physiology and plant biomass allocation. Neither night warming nor day warming significantly affected biomass accumulation and allocation. Height growth increased with night warming in Ochroma pyramidale, but decreased with day warming in late-successional species. Night warming resulted in acclimation of dark respiration. Day warming resulted in acclimation of photosynthesis in early-successional species, but warming decreased photosynthesis in late-successional tree species. The seedling-to-sapling transition is a critical stage in the life of trees. We found no evidence that in this juvenile growth phase moderate increases in mean temperature reduce the performance of tropical trees, although increases in peak daytime temperature may negatively impact photosynthesis, especially in late-successional species.
Data from: Mangrove outwelling is a significant source of oceanic exchangeable organic carbon
Exchangeable dissolved organic carbon (EDOC) makes up a significant proportion of the oceanic dissolved organic carbon (DOC) pool, yet EDOC sources to the coastal ocean are poorly constrained. We measured the exchange of EDOC and concentrations of EDOC and DOC in mangrove waters over a 26° latitudinal gradient. A clear latitudinal trend was observed, with the highest EDOC concentrations in the tropics. EDOC exports to the coastal ocean were 4.7 ± 1.9 mmol m−2 d−1, equivalent to 11% of DOC exports (42.1 ± 6.7 mmol m−2 d−1). Pore-water and groundwater exchange were minor sources of EDOC. EDOC concentrations were equal to 13% ± 4% of DOC concentrations. Based on previous global DOC export estimates, and our EDOC : DOC ratios, mangroves outwell 3.1 Tg C yr−1 as EDOC, equivalent to ∼ 60% of the global EDOC flux from the ocean to the atmosphere. However, seasonality of mangrove EDOC cycling requires further research.
Data from: Repeatable, continuous and real-time estimates of coupled nitrogenase activity and carbon exchange at the whole-plant scale
1. Symbiotic nitrogen fixation (SNF) by higher plants and their bacterial symbionts is a globally important input of nitrogen. Our understanding of the mechanisms that control SNF and the timescales over which they operate has been constrained by limitations of the existing methods for measuring SNF. One method, Acetylene Reduction Assays by Cavity-ring down laser Absorption Spectroscopy (ARACAS), seems promising, as it is highly sensitive and gives rapid, continuous, repeatable and real-time measurements of nitrogenase activity. ARACAS has been used to study nitrogen fixation in lichens, mosses and asymbiotic bacteria, but adapting it to higher plants poses challenges because acetylene and ethylene can influence plant function. 2. Here we report modifications to ARACAS that allow it to be used on higher plants in an environmentally-controlled incubation chamber. The modifications include lower concentrations of acetylene (2%) and ethylene and concurrent measurements of whole chamber CO2 exchange, H2O exchange and nitrogenase activity, linking nitrogenase activity to whole-plant rates of photosynthesis and respiration. 3. After propagating the error terms from all sources, we establish the following parameters of the method: (A) The detection limit of our method was 2-3 ppbv C2H4 hr-1, although it rose substantially when we used tank-derived acetylene, which has much higher ethylene contamination; (B) Repeated measures at a frequency of 3 days or longer did not diminish nitrogenase activity or photosynthesis, although daily measurements diminished nitrogenase activity; (C) This method can detect changes at timescales as short as seconds; (D) Continuous measurement of nitrogenase activity is maintained above 90% of the maximum rate for 7.0 ± 1.3 (mean ± SD) hours. 4. This method has the potential to improve our understanding of the controls over SNF and therefore how SNF and global nitrogen and carbon cycling are likely to be affected by global change.
Ericsson LM private branch telephone exchange
Like the Siemens & Halske AG company in Germany, Lars Magnus Ericsson benefited significantly from the negligence of Alexander Graham Bell, the inventor of the telephone, regarding patents. As early as the 1870s, Ericsson established a company to produce and repair LM Ericsson telephone equipment. His factory supplied high quality telephone equipment to the Scandinavian markets at prices below those of the Bell Telephone Company. LM Ericsson six-number private branch exchange was used for handling an internal telephone network, for example at home, or in an office or small company. The exchange was not designed to work with the city network, although it operated in the central battery (CB) system, i.e., from an external power supply instead of its own inductor, as is typical for exchanges with a similar purpose. Manufacturer: Ericsson LM, ca. 1910 Inv. No.: MIM1097/VIII-36 Model prepared on the basis of photogrammetric measurements Licence: CC BY-NC-SA Source: Objaverse 1.0 / Sketchfab
Accurate exchange-correlation energies for the warm dense electron gas
<p>Raw density matrix quantum Monte Carlo data for the spin polarised uniform electron at finite temperatures.</p>
Data for MWR article "The consequences of surface-exchange coefficient uncertainty on an otherwise highly predictable major hurricane"
<p>This repository contains the model code, initial and boundary conditions and the namelist settings needed to reproduce the results of "The consequences of surface-exchange coefficient uncertainty on an otherwise highly predictable major hurricane".</p>
Three-layer exchange flow patterns driven by differential stratification in a micro-tidal fjord
<p>The datasets show transects at the mouth and along the Swedish Gullmar Fjord. They are taken from a realistic 3D model and were used to investigate three-layer exchange flows at the sill of the fjord.</p>
222Rn tracing groundwater–lake water exchange in the transitional lake
<p>There are three tables including continuous monitoring data, profile radon activity data and sediments experiment data. The continuous monitoring table includes the time of continuous monitoring, radon in the profile, lake water temperature, and wind speed. Lake water volume, sediment mass, overlying water radon activity, wet density, porosity, pore water radon activity, and radon released per unit volume of sediment are listed in the sediment experimental data table.</p>
A New and less corrosive Method for the Activation of Cation Exchange Membranes used in tubular PEM Electrolyzers
<p>Data presented in the article with the same title</p>
Introducing a transition domain for describing the solute exchange between macropores/fractures and matrix in dual-permeability system
<p>出口 1 至 5 的浓度值和出口处的总浓度记录在"实验数据"中。图 8 至 10 中的仿真结果数据记录在"仿真结果"中。构建数值模型的方法记录在"数值模拟"中,需要 COMSOL Multiphysics 将其打开。</p>
Code and Data for Salish Exchange Dynamics paper
<p>This is a compressed (zipped) folder containing all the data files, python code, and output files associated with the manuscript "Estuarine Exchange Flow in the Salish Sea" by Parker MacCready and W. Rockwell Geyer, submitted to Journal of Geophysical Research - Oceans.</p>
Validating the simulation of beam-ion charge exchange in MAST Upgrade
<p>The data that support the findings of the scientific article: P. Ollus et al. (2023) "Validating the simulation of beam-ion charge exchange in MAST Upgrade", Plasma Phys. Control. Fusion.</p>
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.