Browsing by Subject "LIGHT"

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  • Kassamakov, Ivan; Lecler, Sylvain; Nolvi, Anton; Leong-Hoi, Audrey; Montgomery, Paul; Haeggström, Edward (2017)
    We present quantitative three dimensional images of grooves on a writable Blu-ray Disc based on a single objective Mirau type interferometric microscope, enhanced with a microsphere which is considered as a photonic nanojet source. Along the optical axis the resolution of this microsphere assisted interferometry system is a few nanometers while the lateral resolution is around 112 nm. To understand the physical phenomena involved in this kind of imaging we have modelled the interaction between the photonic jet and the complex disc surface. Agreement between simulation and experimental results is demonstrated. We underline that although the ability of the microsphere to generate a photonic nanojet does not alone explain the resolution of the interferometer, the nanojet can be used to try to understand the imaging process. To partly explain the lateral super-resolution, the potential role of coherence is illustrated. The presented modality may have a large impact on many fields from bio-medicine to nanotechnology.
  • Hepojoki, Satu; Nurmi, Visa; Vaheri, Antti; Hedman, Klaus; Vapalahti, Olli; Hepojoki, Jussi (2014)
  • Matlashov, Mikhail E.; Shcherbakova, Daria M.; Alvelid, Jonatan; Baloban, Mikhail; Pennacchietti, Francesca; Shemetov, Anton A.; Testa, Ilaria; Verkhusha, Vladislav V. (2020)
    Bright monomeric near-infrared (NIR) fluorescent proteins (FPs) are in high demand as protein tags for multicolor microscopy and in vivo imaging. Here we apply rational design to engineer a complete set of monomeric NIR FPs, which are the brightest genetically encoded NIR probes. We demonstrate that the enhanced miRFP series of NIR FPs, which combine high effective brightness in mammalian cells and monomeric state, perform well in both nanometer-scale imaging with diffraction unlimited stimulated emission depletion (STED) microscopy and centimeter-scale imaging in mice. In STED we achieve -40nm resolution in live cells. In living mice we detect -10(5) fluorescent cells in deep tissues. Using spectrally distinct monomeric NIR FP variants, we perform two-color live-cell STED microscopy and two-color imaging in vivo. Having emission peaks from 670nm to 720nm, the next generation of miRFPs should become versatile NIR probes for multiplexed imaging across spatial scales in different modalities.
  • Sievänen, Risto; Raumonen, Pasi; Perttunen, Jari; Nikinmaa, Eero Heikki; Kaitaniemi, Pekka Juhani (2018)
    Background and Aims: Functional-structural plant models (FSPMs) allow simulation of tree crown development as the sum of modular (e.g. shoot-level) responses triggered by the local environmental conditions. The actual process of space filling by the crowns can be studied. Although the FSPM simulations are at organ scale, the data for their validation have usually been at more aggregated levels (whole-crown or whole-tree). Measurements made by terrestrial laser scanning (TLS) that have been segmented into elementary units (internodes) offer a phenotyping tool to validate the FSPM predictions at levels comparable with their detail. We demonstrate the testing of different formulations of crown development of Scots pine trees in the LIGNUM model using segmented TLS data. Methods: We made TLS measurements from four sample trees growing in a forest on a relatively poor soil from sapling size to mature stage. The TLS data were segmented into intenodes. The segmentation also produced information on whether needles were present in the internode. We applied different formulations of crown development (flushing of buds and length of growth of new internodes) in LIGNUM. We optimized the parameter values of each formulation using genetic algorithms to observe the best fit of LIGNUM simulations to the measured trees. The fitness function in the estimation combined both tree-level characteristics (e.g. tree height and crown length) and measures of crown shape (e.g. spatial distribution of needle area). Key Results: Comparison of different formulations against the data indicates that the Extended Borchert- Honda model for shoot elongation works best within LIGNUM. Control of growth by local density in the crown was important for all shoot elongation formulations. Modifying the number of lateral buds as a function of local density in the crown was the best way to accomplish density control. Conclusions: It was demonstrated how segmented TLS data can be used in the context of a shoot-based model to select model components.
  • Stepanenko, Olesya V.; Baloban, Mikhail; Bublikov, Grigory S.; Shcherbakova, Daria M.; Stepanenko, Olga V.; Turoverov, Konstantin K.; Kuznetsova, Irina M.; Verkhusha, Vladislav Vitaliyevich (2016)
    Fluorescent proteins (FPs) engineered from bacterial phytochromes attract attention as probes for in vivo imaging due to their near-infrared (NIR) spectra and use of available in mammalian cells biliverdin (BV) as chromophore. We studied spectral properties of the iRFP670, iRFP682 and iRFP713 proteins and their mutants having Cys residues able to bind BV either in both PAS (Cys15) and GAF (Cys256) domains, in one of these domains, or without these Cys residues. We show that the absorption and fluorescence spectra and the chromophore binding depend on the location of the Cys residues. Compared with NIR FPs in which BV covalently binds to Cys15 or those that incorporate BV noncovalently, the proteins with BV covalently bound to Cys256 have blue-shifted spectra and higher quantum yield. In dimeric NIR FPs without Cys15, the covalent binding of BV to Cys256 in one monomer allosterically inhibits the covalent binding of BV to the other monomer, whereas the presence of Cys15 allosterically promotes BV binding to Cys256 in both monomers. The NIR FPs with both Cys residues have the narrowest blue-shifted spectra and the highest quantum yield. Our analysis resulted in the iRFP713/Val256Cys protein with the highest brightness in mammalian cells among available NIR FPs.
  • Ren, Hao; Yang, Peng; Winnik, Francoise M. (2020)
    Azo dyes, such as azobenzene, are able to convert absorbed light into motion or deformation on the macroscopic scale on the basis of their remarkable ability to undergo repeatedly and in 100% yield reversibletrans-to-cisphotoisomerization. Current needs for multiresponsive and fast photoswitches have led to the development of heteroaryl azo dyes, such as azopyridine. This remarkable azo compound combines the photoresponse of the azo chromophore with the chemistry of the pyridine ring, in particular its responsiveness to changes in pH and its ability to form hydrogen- and halogen-bonds. This mini-review summarizes key features of the photoisomerization of polymer-tethered azopyridine in aqueous media and describes a few recent research accomplishments in emerging areas that have benefited of the fast thermalcis-to-transrelaxation characteristics of azopyridinium or H-bonded azopyridine. It also discusses the effects of the photoisomerization of azopyridine on the thermoresponsive properties of azopyridine-tethered heat-sensitive polymers. Overall, azopyridine is a highly versatile actuator to consider when designing photo/multiresponsive polymeric materials.
  • Hontani, Yusaku; Shcherbakova, Daria M.; Baloban, Mikhail; Zhu, Jingyi; Verkhusha, Vladislav; Kennis, John T. M. (2016)
    Near-infrared fluorescent proteins (NIR FPs) engineered from bacterial phytochromes (BphPs) are of great interest for in vivo imaging. They utilize biliverdin (BV) as a chromophore, which is a heme degradation product, and therefore they are straightforward to use in mammalian tissues. Here, we report on fluorescence properties of NIR FPs with key alterations in their BV binding sites. BphP1-FP, iRFP670 and iRFP682 have Cys residues in both PAS and GAF domains, rather than in the PAS domain alone as in wild-type BphPs. We found that NIR FP variants with Cys in the GAF or with Cys in both PAS and GAF show blue-shifted emission with long fluorescence lifetimes. In contrast, mutants with Cys in the PAS only or no Cys residues at all exhibit red-shifted emission with shorter lifetimes. Combining these results with previous biochemical and BphP1-FP structural data, we conclude that BV adducts bound to Cys in the GAF are the origin of bright blue-shifted fluorescence. We propose that the long fluorescence lifetime follows from (i) a sterically more constrained thioether linkage, leaving less mobility for ring A than in canonical BphPs, and (ii) that pi-electron conjugation does not extend on ring A, making excited-state deactivation less sensitive to ring A mobility.
  • Annila, A. (2015)
    Spectrum of cosmic rays follows a broken power law over twelve orders of magnitude. Since ubiquitous power laws are manifestations of the principle of least action, we interpret the spectrum accordingly. Our analysis complies with understanding that low-energy particles originate mostly from rapidly receding sources throughout the cosmos. The flux peaks about proton rest energy whereafter it decreases because fewer and fewer receding sources are energetic enough to provide particles with high enough velocities to compensate for the recessional velocities. Above 10(15.6) eV the flux from the expanding Universe diminishes below the flux from the nearby nonexpanding part of the Universe. In this spectral feature, known as the "knee," we relate to a distance of about 1.3 Mpc where the gravitational potential tallies the energy density of free space. At higher energies particles decelerate in a dissipative manner to attain thermodynamic balance with the vacuum. At about 10(17.2) eV a distinct dissipative mechanism opens up for protons to slow down by electron-positron pair production. At about 10(19.6) eV a more effective mechanism opens up via pion production. All in all, the universal principle discloses that the broad spectrum of cosmic rays probes the structure of space from cosmic distances down to microscopic details.
  • Lihavainen, Heikki; Asmi, Eija; Aaltonen, Veijo; Makkonen, Ulla; Kerminen, Veli-Matti (2015)
    We used more than five years of continuous aerosol measurements to estimate the direct radiative feedback parameter associated with the formation of biogenic secondary organic aerosol (BSOA) at a remote continental site at the edge of the boreal forest zone in Northern Finland. Our upper-limit estimate for this feedback parameter during the summer period (ambient temperatures above 10 degrees C) was -97 +/- 66 mWm(-2) K-1 (mean +/- STD) when using measurements of the aerosol optical depth (f(AOD)) and -63 +/- 40 mWm(-2) K-1 when using measurements of the 'dry' aerosol scattering coefficient at the ground level (f(sigma)). Here STD represents the variability in f caused by the observed variability in the quantities used to derive the value of f. Compared with our measurement site, the magnitude of the direct radiative feedback associated with BSOA is expected to be larger in warmer continental regions with more abundant biogenic emissions, and even larger in regions where biogenic emissions are mixed with anthropogenic pollution.
  • Magney, Troy S.; Frankenberg, Christian; Kohler, Philipp; North, Gretchen; Davis, Thomas S.; Dold, Christian; Dutta, Debsunder; Fisher, Joshua B.; Grossmann, Katja; Harrington, Alexis; Hatfield, Jerry; Stutz, Jochen; Sun, Ying; Porcar-Castell, Albert (2019)
    Novel satellite measurements of solar-induced chlorophyll fluorescence (SIF) can improve our understanding of global photosynthesis; however, little is known about how to interpret the controls on its spectral variability. To address this, we disentangle simultaneous drivers of fluorescence spectra by coupling active and passive fluorescence measurements with photosynthesis. We show empirical and mechanistic evidence for where, why, and to what extent leaf fluorescence spectra change. Three distinct components explain more than 95% of the variance in leaf fluorescence spectra under both steady-state and changing illumination conditions. A single spectral shape of fluorescence explains 84% of the variance across a wide range of species. The magnitude of this shape responds to absorbed light and photosynthetic up/down regulation; meanwhile, chlorophyll concentration and nonphotochemical quenching control 9% and 3% of the remaining spectral variance, respectively. The spectral shape of fluorescence is remarkably stable where most current satellite retrievals occur (far-red, >740nm), and dynamic downregulation of photosynthesis reduces fluorescence magnitude similarly across the 670- to 850-nm range. We conduct an exploratory analysis of hourly red and far-red canopy SIF in soybean, which shows a subtle change in red:far-red fluorescence coincident with photosynthetic downregulation but is overshadowed by longer-term changes in canopy chlorophyll and structure. Based on our leaf and canopy analysis, caution should be taken when attributing large changes in the spectral shape of remotely sensed SIF to plant stress, particularly if data acquisition is temporally sparse. Ultimately, changes in SIF magnitude at wavelengths greater than 740 nm alone may prove sufficient for tracking photosynthetic dynamics. Plain Language Summary Satellite remote sensing provides a global picture of photosynthetic activity-allowing us to see when, where, and how much CO2 plants are assimilating. To do this, satellites measure a small emission of energy from the plants called chlorophyll fluorescence. However, this measurement is typically made across a narrow wavelength range, while the emission spectrum (650-850 nm) is quite dynamic. We show where, why, and to what extent leaf fluorescence spectra change across a diverse range of species and conditions, ultimately informing canopy remote sensing measurements. Results suggest that wavelengths currently used by satellites are stable enough to track the downregulation of photosynthesis resulting from stress, while spectral shape changes respond more strongly to dynamics in canopy structure and chlorophyll concentration.
  • Multia, Evgen; Tear, Crystal Jing Ying; Palviainen, Mari; Siljander, Pia R-M; Riekkola, Marja-Liisa (2019)
    A new, fast and selective immunoaffinity chromatographic method including a methacrylate-based convective interaction media (CIM (R)) disk monolithic column, immobilized with anti-human CD61 antibody, was developed for the isolation of CD61-containing platelet-derived extracellular vesicles (EVs) from plasma. The isolated EVs were detected and size characterized by asymmetrical flow field-flow fractionation (AsFlFFF) with multi-angle light-scattering (MALS) and dynamic light-scattering (DLS) detection, and further confirmed by nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM). The mean size of platelet-derived EV isolates from the anti-CD61 CIM (R) disk monolithic column were 174 nm (SD 60 nm) based on the NTA results. These results indicated a successful isolation of platelet-derived EVs, which was confirmed by Western blotting the isolates against the EV-specific markers CD9 and TSG101 together with transmission electron microscopy. Additional elucidation of MALS and DLS data provided detailed information of the size distribution of the isolated fractions, confirming the successful isolation of also small platelet-derived EVs ranging from 30 to 130 nm based on the hydrodynamic radii. The isolation procedure took only 19 min and the time can be even further decreased by increasing the flow rate. The same immunoaffinity chromatographic procedure, following AsFlFFF allowed also the isolation and characterization of platelet-derived EVs from plasma in under 60 min. Since it is possible to regenerate the anti-CD61 disk for multiple uses, the methodology developed in this study provides a viable substitution and addition to the conventional EV isolation procedures. (C) 2019 Elsevier B.V. All rights reserved.
  • Tossavainen, Marika; Ilyass, Usman; Ollilainen, Velimatti; Valkonen, Kalle; Ojala, Anne; Romantschuk, Martin (2019)
    Nitrogen limitation is considered a good strategy for enhancement of algal lipid production while conversely N repletion has been shown to result in biomass rich in proteins. In this study, the influence of long-term N limitation on Euglena gracilis fatty acid (FA), protein, chlorophyll a, and carotenoid concentrations was studied in N limited cultures. Biomass composition was analyzed from three-time points from N starved late stationary phase cultures, exposed to three different initial N concentrations in the growth medium. Total lipid content increased under N limitation in ageing cultures, but the low N content and prolonged cultivation time resulted in the formation of a high proportion of saturated FAs. Furthermore, growth as well as the production of proteins, chlorophyll a and carotenoids were enhanced in higher N concentrations and metabolism of these cellular components stayed stable during the stationary growth phase. Our findings showed that a higher N availability and a shorter cultivation time is a good strategy for efficient E. gracilis biomass production, regardless of whether the produced biomass is intended for maximal recovery of polyunsaturated FAs, proteins, or photosynthetic pigments. Additionally, we showed an increase of neoxanthin, beta-carotene, and diadinoxanthin as a response to higher N availability.
  • Kassamakov, Ivan; Ylitalo, Tuomo; Nolvi, Anton; Raatikainen, Pekka; Paananen, Riku; Haeggström, Edward (SPIE - the international society for optics and photonics, 2019)
    Proceedings of SPIE
    Photonic nanojet interferometry (PM) permits three dimensional (3D) label-free and super-resolution surface characterization. PM is based on coherence scanning interferometry (CSI), featuring Angstrom level vertical resolution. Being an optical far-field technique, CSI is diffraction limited and according to the Abbe criteria, can laterally resolve, points that are separated by a few hundred nanometers. We overcame this limitation by using dielectric microspheres that generate photonic nanojets. Now sub 100 nm features can laterally be resolved while preserving the vertical resolution of the CSI system. The microsphere material could be polymer or glass with a diameter between 8 and 12 mu m, which limits the field of view (FoV) of the PNI system to similar to 10 mu m(2). Here we present a method to increase the FoV of a PNI based device by stitching a sequence of adjacent 3D images. We imaged a recordable Blu-ray Disc (BR-D) using a custom built Mirau type scanning white light interferometer with enhanced lateral resolution. Four 3D super-resolution images with constant 80% overlap, were stitched together using in-house software. The resulting high fidelity image shows that 45% overlap and the above described procedure could be used to enlarge the FoV of label-free 3D super-resolution imaging systems.
  • Potes, M.; Salgado, R.; Costa, M. J.; Morais, M.; Bortoli, D.; Kostadinov, I.; Mammarella, I. (2017)
    The study of lake-atmosphere interactions was the main purpose of a 2014 summer experiment at Alqueva reservoir in Portugal. Near-surface fluxes of momentum, heat and mass [water vapour (H2O) and carbon dioxide (CO2)] were obtained with the new Campbell Scientific's IRGASON Integrated Open-Path CO2/H2O Gas Analyser and 3D Sonic Anemometer between 2 June and 2 October. On average, the reservoir was releasing energy in the form of sensible and latent heat flux during the study period. At the end of the 75 d, the total evaporation was estimated as 490.26 mm. A high correlation was found between the latent heat flux and the wind speed (R = 0.97). The temperature gradient between air and water was positive between 12 and 21 UTC, causing a negative sensible heat flux, and negative during the rest of the day, triggering a positive sensible heat flux. The reservoir acted as a sink of atmospheric CO2 with an average rate of -0.026 mg m(-2) s(-1). However, at a daily scale we found an unexpected uptake between 0 and 9 UTC and almost null flux between 13 and 19 UTC. Potential reasons for this result are further discussed. The net radiation was recorded for the same period and water column heat storage was estimated using water temperature profiles. The energy balance closure for the analysed period was 81%. In-water solar spectral downwelling irradiance profiles were measured with a new device allowing measurements independent of the solar zenith angle, which enabled the computation of the attenuation coefficient of light in the water column. The average attenuation coefficient for the photosynthetically active radiation spectral region varied from 0.849 +/- 0.025 m(-1) on 30 July to 1.459 +/- 0.007 m(-1) on 25 September.
  • Rajewicz, Paulina A.; Atherton, Jon; Alonso, Luis; Porcar-Castell, Albert (2019)
    Successful measurements of chlorophyll fluorescence (ChlF) spectral properties (typically in the wavelength range of 650-850 nm) across plant species, environmental conditions, and stress levels are a first step towards establishing a quantitative link between solar-induced chlorophyll fluorescence (SIF), which can only be measured at discrete ChlF spectral bands, and photosynthetic functionality. Despite its importance and significance, the various methodologies for the estimation of leaf-level ChlF spectral properties have not yet been compared, especially when applied to leaves with complex morphology, such as needles. Here we present, to the best of our knowledge, a first comparison of protocols for measuring leaf-level ChlF spectra: a custom-made system designed to measure ChlF spectra at ambient and 77 K temperatures (optical chamber, OC), the widely used FluoWat leaf clip (FW), and an integrating sphere setup (IS). We test the three methods under low-light conditions, across two broadleaf species and one needle-like species. For the conifer, we characterize the effect of needle arrangements: one needle, three needles, and needle mats with as little gap fraction as technically possible. We also introduce a simple baseline correction method to account for non-fluorescence-related contributions to spectral measurements. Baseline correction was found especially useful in recovering the spectra nearby the filter cut-off. Results show that the shape of the leaf-level ChlF spectra remained largely unaffected by the measurement methodology and geometry in OC and FW methods. Substantially smaller red/far-red ratios were observed in the IS method. The comparison of needle arrangements indicated that needle mats could be a practical solution to investigate temporal changes in ChlF spectra of needle-like leaves as they produced more reproducible results and higher signals.
  • Adam, J.; Brucken, E. J.; Chang, B.; Kim, D. J.; Mieskolainen, M. M.; Orava, R.; Rak, J.; Räsänen, S. S.; Snellman, T. W.; Trzaska, W. H.; Viinikainen, J.; The ALICE collaboration (2017)
    The azimuthal correlations of D mesons with charged particles were measured with the ALICE apparatus in pp collisions at root s = 7 TeV and p-Pb collisions at root sNN = 5.02 TeV at the Large Hadron Collider. D-0, D+, and D*+ mesons and their charge conjugates with transverse momentum 3 <pT <16 GeV/c and rapidity in the nucleonnucleon centre-of-mass system vertical bar y(cms)vertical bar <0.5 (pp collisions) and -0.96 <y(cms) <0.04 (p-Pb collisions) were correlated to charged particles with p(T) > 0.3 GeV/c. The yield of charged particles in the correlation peak induced by the jet containing the D meson and the peak width are compatible within uncertainties in the two collision systems. The data are described within uncertainties by Monte-Carlo simulations based on PYTHIA, POWHEG, and EPOS 3 event generators.
  • Kluger, Nicolas; Koskenmies, Sari; Jeskanen, Leila; Övermark, Meri; Saksela, Olli (2014)
  • Collett, Thomas; Montanari, Francesco; Räsänen, Syksy (2019)
    We present the first determination of the Hubble constant H-0 from strong lensing time delay data and type Ia supernova luminosity distances that is independent of the cosmological model. We also determine the spatial curvature model independently. We assume that light propagation over long distances is described by the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric and geometrical optics holds, but make no assumption about the contents of the Universe or the theory of gravity on cosmological scales. We find H-0 = 75.7(-4.4)(+4.5) km/s/Mpc and Omega(K0) = 0.12(-0.25)(+0.27). This is a 6% determination of H-0. A weak prior from the cosmic microwave background on the distance to the last scattering surface improves this to H-0 = 76.8(-3.8)(+4.2) km/s/Mpc and Omega(K0) = 0.18(-0.18)(+0.25). Assuming a zero spatial curvature, we get H-0 = 74.2(-2.9)(+3.0) km/s/Mpc, a precision of 4%. The measurements also provide a consistency test of the FLRW metric: we find no evidence against it.
  • Saajasto, Mika; Juvela, Mika; Malinen, Johanna (2018)
    Context. Regarding the evolution of dust grains from diffuse regions of space to dense molecular cloud cores, many questions remain open. Scattering at near-infrared wavelengths, or "cloudshine", can provide information on cloud structure, dust properties, and the radiation field that is complementary to mid-infrared "coreshine" and observations of dust emission at longer wavelengths. Aims. We examine the possibility of using near-infrared scattering to constrain the local radiation field and the dust properties, the scattering and absorption efficiency, the size distribution of the grains, and the maximum grain size. Methods. We use radiative transfer modelling to examine the constraints provided by the J, H, and K bands in combination with mid-infrared surface brightness at 3.6 mu m. We use spherical one-dimensional and elliptical three-dimensional cloud models to study the observable effects of different grain size distributions with varying absorption and scattering properties. As an example, we analyse observations of a molecular cloud in Taurus, TMC-1N. Results. The observed surface brightness ratios of the bands change when the dust properties are changed. However, even a change of +/- 10% in the surface brightness of one band changes the estimated power-law exponent of the size distribution gamma by up to similar to 30% and the estimated strength of the radiation field K-ISRF by up to similar to 60%. The maximum grain size A(max) and gamma are always strongly anti-correlated. For example, overestimating the surface brightness by 10% changes the estimated radiation field strength by similar to 20% and the exponent of the size distribution by similar to 15%. The analysis of our synthetic observations indicates that the relative uncertainty of the parameter distributions are on average A(max), gamma similar to 25%, and the deviation between the estimated and correct values Delta Q <15%. For the TMC-1N observations, a maximum grain size A(max) > 1.5 mu m and a size distribution with gamma > 4.0 have high probability. The mass weighted average grain size is <a(m)> = 0.113 mu m. Conclusions. We show that scattered infrared light can be used to derive meaningful limits for the dust parameters. However, errors in the surface brightness data can result in considerable uncertainties on the derived parameters.
  • Li, Xuefei; Schmid, Bernhard; Wang, Fei; Paine, C. E. Timothy (2016)
    Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species.