scholarly journals Rapid estimation of photosynthetic leaf traits of tropical plants in diverse environmental conditions using reflectance spectroscopy

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258791
Author(s):  
Julien Lamour ◽  
Kenneth J. Davidson ◽  
Kim S. Ely ◽  
Jeremiah A. Anderson ◽  
Alistair Rogers ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Maximum Rate ◽  
Reflectance Spectroscopy ◽  
Training Dataset ◽  
Utilization Rate ◽  
Tropical Species ◽  
Least Squares Regression ◽  
Sampled Data ◽  
Wide Range ◽  
Photosynthetic Traits

Tropical forests are one of the main carbon sinks on Earth, but the magnitude of CO2 absorbed by tropical vegetation remains uncertain. Terrestrial biosphere models (TBMs) are commonly used to estimate the CO2 absorbed by forests, but their performance is highly sensitive to the parameterization of processes that control leaf-level CO2 exchange. Direct measurements of leaf respiratory and photosynthetic traits that determine vegetation CO2 fluxes are critical, but traditional approaches are time-consuming. Reflectance spectroscopy can be a viable alternative for the estimation of these traits and, because data collection is markedly quicker than traditional gas exchange, the approach can enable the rapid assembly of large datasets. However, the application of spectroscopy to estimate photosynthetic traits across a wide range of tropical species, leaf ages and light environments has not been extensively studied. Here, we used leaf reflectance spectroscopy together with partial least-squares regression (PLSR) modeling to estimate leaf respiration (Rdark25), the maximum rate of carboxylation by the enzyme Rubisco (Vcmax25), the maximum rate of electron transport (Jmax25), and the triose phosphate utilization rate (Tp25), all normalized to 25°C. We collected data from three tropical forest sites and included leaves from fifty-three species sampled at different leaf phenological stages and different leaf light environments. Our resulting spectra-trait models validated on randomly sampled data showed good predictive performance for Vcmax25, Jmax25, Tp25 and Rdark25 (RMSE of 13, 20, 1.5 and 0.3 μmol m-2 s-1, and R2 of 0.74, 0.73, 0.64 and 0.58, respectively). The models showed similar performance when applied to leaves of species not included in the training dataset, illustrating that the approach is robust for capturing the main axes of trait variation in tropical species. We discuss the utility of the spectra-trait and traditional gas exchange approaches for enhancing tropical plant trait studies and improving the parameterization of TBMs.

Use of reflectance spectroscopy to estimate the organic carbon and CaCO3 contents of soils

2012 ◽  
Vol 61 (2) ◽  
pp. 277-290 ◽  
Author(s):  
Ádám Csorba ◽  
Vince Láng ◽  
László Fenyvesi ◽  
Erika Michéli
Keyword(s):  
Organic Carbon ◽  
Least Squares ◽  
Partial Least Squares ◽  
Partial Least Squares Regression ◽  
Mean Squared Error ◽  
Reflectance Spectroscopy ◽  
Least Squares Regression ◽  
Root Mean Squared Error ◽  
Squared Error

Napjainkban egyre nagyobb igény mutatkozik olyan technológiák és módszerek kidolgozására és alkalmazására, melyek lehetővé teszik a gyors, költséghatékony és környezetbarát talajadat-felvételezést és kiértékelést. Ezeknek az igényeknek felel meg a reflektancia spektroszkópia, mely az elektromágneses spektrum látható (VIS) és közeli infravörös (NIR) tartományában (350–2500 nm) végzett reflektancia-mérésekre épül. Figyelembe véve, hogy a talajokról felvett reflektancia spektrum információban nagyon gazdag, és a vizsgált tartományban számos talajalkotó rendelkezik karakterisztikus spektrális „ujjlenyomattal”, egyetlen görbéből lehetővé válik nagyszámú, kulcsfontosságú talajparaméter egyidejű meghatározása. Dolgozatunkban, a reflektancia spektroszkópia alapjaira helyezett, a talajok ösz-szetételének meghatározását célzó módszertani fejlesztés első lépéseit mutatjuk be. Munkánk során talajok szervesszén- és CaCO3-tartalmának megbecslését lehetővé tévő többváltozós matematikai-statisztikai módszerekre (részleges legkisebb négyzetek módszere, partial least squares regression – PLSR) épülő prediktív modellek létrehozását és tesztelését végeztük el. A létrehozott modellek tesztelése során megállapítottuk, hogy az eljárás mindkét talajparaméter esetében magas R2értéket [R2(szerves szén) = 0,815; R2(CaCO3) = 0,907] adott. A becslés pontosságát jelző közepes négyzetes eltérés (root mean squared error – RMSE) érték mindkét paraméter esetében közepesnek mondható [RMSE (szerves szén) = 0,467; RMSE (CaCO3) = 3,508], mely a reflektancia mérési előírások standardizálásával jelentősen javítható. Vizsgálataink alapján arra a következtetésre jutottunk, hogy a reflektancia spektroszkópia és a többváltozós kemometriai eljárások együttes alkalmazásával, gyors és költséghatékony adatfelvételezési és -értékelési módszerhez juthatunk.

Inhibition kinetics for propionate degradation using propionate-enriched mixed cultures

1998 ◽  
Vol 38 (8-9) ◽  
pp. 443-451 ◽  
Author(s):  
S. H. Hyun ◽  
J. C. Young ◽  
I. S. Kim
Keyword(s):  
Phase I ◽  
Competitive Inhibition ◽  
Gas Production ◽  
Phase Iii ◽  
Utilization Rate ◽  
Inhibition Kinetics ◽  
Wide Range ◽  
Propionate Degradation ◽  
Acetate Utilization ◽  
Velocity Coefficient

To study propionate inhibition kinetics, seed cultures for the experiment were obtained from a propionate-enriched steady-state anaerobic Master Culture Reactor (MCR) operated under a semi-continuous mode for over six months. The MCR received a loading of 1.0 g propionate COD/l-day and was maintained at a temperature of 35±1°C. Tests using serum bottle reactors consisted of four phases. Phase I tests were conducted for measurement of anaerobic gas production as a screening step for a wide range of propionate concentrations. Phase II was a repeat of phase I but with more frequent sampling and detailed analysis of components in the liquid sample using gas chromatography. In phase III, different concentrations of acetate were added along with 1.0 g propionate COD/l to observe acetate inhibition of propionate degradation. Finally in phase IV, different concentrations of propionate were added along with 100 and 200 mg acetate/l to confirm the effect of mutual inhibition. Biokinetic and inhibition coefficients were obtained using models of Monod, Haldane, and Han and Levenspiel through the use of non-linear curve fitting technique. Results showed that the values of kp, maximum propionate utilization rate, and Ksp, half-velocity coefficient for propionate conversion, were 0.257 mg HPr/mg VSS-hr and 200 mg HPr/l, respectively. The values of kA, maximum acetate utilization rate, and KsA, half-velocity coefficient for acetate conversion, were 0.216 mg HAc/mg VSS-hr and 58 mg HAc/l, respectively. The results of phase III and IV tests indicated there was non-competitive inhibition when the acetate concentration in the reactor exceeded 200 mg/l.

scholarly journals TEMPERATURE - GERMINATION RESPONSES OF SUNFLOWER (Helianthus annuus L.) GENOTYPES / GERMINACION COMO REACCION A LA TEMPERATURA EN LOS GENOTIPOS DEL GIRASOL (Helianthus annuus L.) / GERMINATION - RÉACTION À LA TEMPÉRATURE DANS LES GÉNOTYPES DE TOURNESOL (Helianthus annuus L.)

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 97-104
Author(s):  
F.M. Khalifa ◽  
A.A. Schneiter ◽  
E.I. El Tayeb
Keyword(s):  
Seed Germination ◽  
Helianthus Annuus ◽  
Maximum Rate ◽  
Germination Rate ◽  
Thermal Time ◽  
Large Temperature ◽  
Climatic Zones ◽  
Helianthus Annuus L ◽  
Wide Range ◽  
Cardinal Temperature

SUMMARY Seed germination of six sunflower (Helianthus annuus L.) hybrids was investigated across a range of eleven constant temperatures between 5°C and 45°C. Large temperature differences in germination rate 1/t (d-1), cardinal temperature (°C) and thermal time θ (°cd) were observed among hybrids. Base temperatures (Tb) varied between 3.3°C and 6.7°C whereas maximum germination temperatures (Tm) varied between 41.7°C and 48.9°C. Final germination fraction was attained at 15°C - 25°C whereas the maximum rate of germination was attained at 30.4°C - 35.6°C. The maximum germination rate of hybrid USDA 894, the cultivar with the slowest germination rate, was only 50% of that of hybrid EX 47. The low Tb and high Tm of sunflower appear to be one of the factors which explain the successful adaptation of sunflower to a wide range of temperature. These findings are discussed in relation to the origin of the crop and its wide adaptations in diverse habitats and climatic zones.

scholarly journals Lack of Informations about COVID-19 Vaccine: From Implications to Intervention for Supporting Public Health Communications in COVID-19 Pandemic

2021 ◽  
Vol 18 (11) ◽  
pp. 6141
Author(s):  
Silva Guljaš ◽  
Zvonimir Bosnić ◽  
Tamer Salha ◽  
Monika Berecki ◽  
Zdravka Krivdić Dupan ◽  
...  
Keyword(s):  
Vaccine Efficacy ◽  
Health Belief ◽  
Ordinary Least Squares ◽  
Vaccine Hesitancy ◽  
Equal Proportion ◽  
Least Squares Regression ◽  
Online Questionnaire ◽  
Demographic Groups ◽  
Population Immunity ◽  
Wide Range

Lack of knowledge and mistrust towards vaccines represent a challenge in achieving the vaccination coverage required for population immunity. The aim of this study is to examine the opinion that specific demographic groups have about COVID-19 vaccination, in order to detect potential fears and reasons for negative attitudes towards vaccination, and to gain knowledge on how to prepare strategies to eliminate possible misinformation that could affect vaccine hesitancy. The data collection approach was based on online questionnaire surveys, divided into three groups of questions that followed the main postulates of the health belief theory—a theory that helps understanding a behaviour of the public in some concrete surrounding in receiving preventive measures. Ordinary least squares regression analyses were used to examine the influence of individual factors on refusing the vaccine, and to provide information on the perception of participants on the danger of COVID-19 infection, and on potential barriers that could retard the vaccine utility. There was an equal proportion of participants (total number 276) who planned on receiving the COVID-19 vaccine (37%), and of those who did not (36.3%). The rest (26.7%) of participants were still indecisive. Our results indicated that attitudes on whether to receive the vaccine, on how serious consequences might be if getting the infection, as well as a suspicious towards the vaccine efficacy and the fear of the vaccine potential side effects, may depend on participants’ age (<40 vs. >40 years) and on whether they are healthcare workers or not. The barriers that make participants‘ unsure about of receiving the vaccine, such as a distrust in the vaccine efficacy and safety, may vary in different socio-demographic groups and depending on which is the point of time in the course of the pandemic development, as well as on the vaccine availability and experience in using certain vaccine formulas. There is a pressing need for health services to continuously provide information to the general population, and to address the root causes of mistrust through improved communication, using a wide range of policies, interventions and technologies.

Biogeographical Patterns of Light Use efficiency?

2021 ◽  
Author(s):  
David Sandoval ◽  
Iain Colin Prentice
Keyword(s):  
Maximum Rate ◽  
Spatial Organization ◽  
Gross Primary Production ◽  
Incident Light ◽  
Direct Consequence ◽  
Theoretical Explanation ◽  
Light Use Efficiency ◽  
Mountain Regions ◽  
Use Efficiency ◽  
Photosynthetic Traits

&lt;p&gt;The emergent spatial organization of ecosystems in elevational gradients suggest that some ecosystem processes, important enough to shape morphological traits, must show similar patterns.&lt;/p&gt;&lt;p&gt;The most important of these processes, gross primary production (GPP), usually (albeit with some exceptions) decreases with elevation. This was previously thought to be a direct consequence either of the decrease in temperature, or the decrease of incident light due to cloud cover. However, some recent developments in photosynthetic theory, plus the unprecedented availability of ecophysiological data, support the hypothesis that plants acclimate (optimize) their photosynthetic traits to the environment. In this new theoretical context, the temperature is no longer considered as a major constraining factor, except when either freezing or excessively high temperatures inhibit plant function generally.&lt;/p&gt;&lt;p&gt;Two of the most important photosynthetic traits, the maximum rate of carboxylation (V&lt;sub&gt;CMAX&lt;/sub&gt;) and the intrinsic quantum efficiency (&amp;#966;&lt;sub&gt;o&lt;/sub&gt;), vary in opposite directions with increasing elevation. Plants tend to increase V&lt;sub&gt;CMAX&lt;/sub&gt; to compensate for a decrease in the ratio leaf-internal to ambient partial pressures of CO&lt;sub&gt;2&lt;/sub&gt;, while &amp;#966;&lt;sub&gt;o&lt;/sub&gt; increases with temperature up to a plateau. To explore how these different responses, documented at leaf level, converge in emergent spatial patterns at ecosystem scale we considered how elevation shape light use efficiency (defined as the ratio of CO&lt;sub&gt;2&lt;/sub&gt; assimilated over light absorbed) over mountain regions worldwide. We used data from eddy-covariance flux towers, from different networks, located in mountain regions around the world, adding up to 618 station-years of record. To complement our analysis, we included theoretical predictions using an optimality model (P-model) and evaluated changes in the spatial pattern with simulation experiments.&lt;/p&gt;&lt;p&gt;Empirically we found an asymptotic response of LUE to the average daytime temperature during the growing season with increasing elevation, and a small, but globally consistent effect of elevation on LUE. We propose a theoretical explanation for the observation that temperature differences have little impact on the biogeographical pattern of LUE, but we also find that different assumptions on the acclimation of the maximum rate of electron transport (J&lt;sub&gt;MAX&lt;/sub&gt;) and &amp;#966;&lt;sub&gt;o&lt;/sub&gt; change this pattern.&lt;/p&gt;

High-frequency ventilation

1984 ◽  
Vol 64 (2) ◽  
pp. 505-543 ◽  
Author(s):  
J. M. Drazen ◽  
R. D. Kamm ◽  
A. S. Slutsky
Keyword(s):  
Experimental Data ◽  
Gas Exchange ◽  
Dead Space ◽  
Gas Transport ◽  
Physical Models ◽  
High Frequency Ventilation ◽  
General Description ◽  
Wide Range ◽  
Dead Space Volume ◽  
Space Volume

Complete physiological understanding of HFV requires knowledge of four general classes of information: 1) the distribution of airflow within the lung over a wide range of frequencies and VT (sect. IVA), 2) an understanding of the basic mechanisms whereby the local airflows lead to gas transport (sect. IVB), 3) a computational or theoretical model in which transport mechanisms are cast in such a form that they can be used to predict overall gas transport rates (sect. IVC), and 4) an experimental data base (sect. VI) that can be compared to model predictions. When compared with available experimental data, it becomes clear that none of the proposed models adequately describes all the experimental findings. Although the model of Kamm et al. is the only one capable of simulating the transition from small to large VT (as compared to dead-space volume), it fails to predict the gas transport observed experimentally with VT less than equipment dead space. The Fredberg model is not capable of predicting the observed tendency for VT to be a more important determinant of gas exchange than is frequency. The remaining models predict a greater influence of VT than frequency on gas transport (consistent with experimental observations) but in their current form cannot simulate the additional gas exchange associated with VT in excess of the dead-space volume nor the decreased efficacy of HFV above certain critical frequencies observed in both animals and humans. Thus all of these models are probably inadequate in detail. One important aspect of these various models is that some are based on transport experiments done in appropriately scaled physical models, whereas others are entirely theoretical. The experimental models are probably most useful in the prediction of pulmonary gas transport rates, whereas the physical models are of greater value in identifying the specific transport mechanism(s) responsible for gas exchange. However, both classes require a knowledge of the factors governing the distribution of airflow under the circumstances of study as well as requiring detail about lung anatomy and airway physical properties. Only when such factors are fully understood and incorporated into a general description of gas exchange by HFV will it be possible to predict or explain all experimental or clinical findings.

scholarly journals Evaluation of statistical methods for quantifying fractal scaling in water-quality time series with irregular sampling

2018 ◽  
Vol 22 (2) ◽  
pp. 1175-1192 ◽  
Author(s):  
Qian Zhang ◽  
Ciaran J. Harman ◽  
James W. Kirchner
Keyword(s):  
Water Quality ◽  
Time Series ◽  
Irregular Sampling ◽  
Quality Data ◽  
Sampled Data ◽  
Spectral Slope ◽  
Water Quality Data ◽  
Fractal Scaling ◽  
Wide Range ◽  
Irregularly Sampled Data

Abstract. River water-quality time series often exhibit fractal scaling, which here refers to autocorrelation that decays as a power law over some range of scales. Fractal scaling presents challenges to the identification of deterministic trends because (1) fractal scaling has the potential to lead to false inference about the statistical significance of trends and (2) the abundance of irregularly spaced data in water-quality monitoring networks complicates efforts to quantify fractal scaling. Traditional methods for estimating fractal scaling – in the form of spectral slope (β) or other equivalent scaling parameters (e.g., Hurst exponent) – are generally inapplicable to irregularly sampled data. Here we consider two types of estimation approaches for irregularly sampled data and evaluate their performance using synthetic time series. These time series were generated such that (1) they exhibit a wide range of prescribed fractal scaling behaviors, ranging from white noise (β  =  0) to Brown noise (β  =  2) and (2) their sampling gap intervals mimic the sampling irregularity (as quantified by both the skewness and mean of gap-interval lengths) in real water-quality data. The results suggest that none of the existing methods fully account for the effects of sampling irregularity on β estimation. First, the results illustrate the danger of using interpolation for gap filling when examining autocorrelation, as the interpolation methods consistently underestimate or overestimate β under a wide range of prescribed β values and gap distributions. Second, the widely used Lomb–Scargle spectral method also consistently underestimates β. A previously published modified form, using only the lowest 5 % of the frequencies for spectral slope estimation, has very poor precision, although the overall bias is small. Third, a recent wavelet-based method, coupled with an aliasing filter, generally has the smallest bias and root-mean-squared error among all methods for a wide range of prescribed β values and gap distributions. The aliasing method, however, does not itself account for sampling irregularity, and this introduces some bias in the result. Nonetheless, the wavelet method is recommended for estimating β in irregular time series until improved methods are developed. Finally, all methods' performances depend strongly on the sampling irregularity, highlighting that the accuracy and precision of each method are data specific. Accurately quantifying the strength of fractal scaling in irregular water-quality time series remains an unresolved challenge for the hydrologic community and for other disciplines that must grapple with irregular sampling.

Adjustment of Serum Total Calcium for Albumin Concentration: Values Change with Age in Women but Not in Men

1996 ◽  
Vol 33 (1) ◽  
pp. 59-62 ◽  
Author(s):  
R B Payne ◽  
J H Barth
Keyword(s):  
Serum Albumin ◽  
Albumin Concentration ◽  
Least Squares Regression ◽  
Total Calcium ◽  
Computer Data ◽  
Younger Women ◽  
Serum Total Calcium ◽  
Wide Range ◽  
Computer Data Base ◽  
Low Prevalence

A total of 669 women and 609 men were selected from a laboratory computer data base in such a way that they would be expected to have a low prevalence of disturbances of calcium homeostasis but a wide range of serum albumin concentrations. The least squares regression coefficients of total calcium on albumin did not differ between men and women, nor did they differ at different ages. Mean serum albumin-adjusted calcium concentrations did not change with age in men from 1 to 90 years, and values were similar in women aged 1–20 years. However, adjusted calcium concentrations were significantly lower in women aged 21–50 and higher in women aged 61–90 than in younger women and all men. The differences were small and are unlikely to affect clinical interpretation.

scholarly journals Woody species do not differ in dormancy progression: differences in time to budbreak due to forcing and cold hardiness

2021 ◽  
Author(s):  
Al Kovaleski
Keyword(s):  
Maximum Rate ◽  
Path Length ◽  
Cold Hardiness ◽  
Woody Species ◽  
Two Dimensions ◽  
Spring Phenology ◽  
Wide Range ◽  
The Difference ◽  
Response To Temperature ◽  
Phenological Phases

AbstractBudbreak is one of the most observed and studied phenological phases in perennial plants. Two dimensions of exposure to temperature are generally used to model budbreak: accumulation of time spent at low temperatures (chilling); and accumulation of heat units (forcing). These two effects have a well-established negative correlation: the more chilling, the less forcing required for budbreak. Furthermore, temperate plant species are assumed to vary in amount of chilling required to complete endodormancy and begin the transition to breaking bud. Still, prediction of budbreak remains a challenge. The present work demonstrates across a wide range of species how bud cold hardiness must be accounted for to study dormancy and accurately predict time to budbreak. Cold hardiness defines the path length to budbreak, meaning the difference between the cold hardiness buds attain during the winter, and the cold hardiness at which deacclimated buds are predicted to open. This distance varies among species and throughout winter within a species. Increases in rate of cold hardiness loss (deacclimation) measured throughout winter show that chilling controls deacclimation potential – the proportion of the maximum rate response attained at high chill accumulation – which has a sigmoid relationship to chilling accumulation. For forcing, rates of deacclimation increase non-linearly in response to temperature. Comparisons of deacclimation potential show a dormancy progresses similarly for all species. This observation suggests that comparisons of physiologic and genetic control of dormancy requires an understanding of cold hardiness dynamics and the necessity for an update of the framework for studying dormancy and its effects on spring phenology.

scholarly journals Technical note: GUARD – An automated fluid sampler preventing sample alteration by contamination, evaporation and gas exchange, suitable for remote areas and harsh conditions

2018 ◽  
Author(s):  
Arno Hartmann ◽  
Marc Luetscher ◽  
Ralf Wachter ◽  
Philipp Holz ◽  
Elisabeth Eiche ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Field Experiments ◽  
Hydrological Cycle ◽  
Technical Note ◽  
Production Costs ◽  
Environmental Research ◽  
Remote Areas ◽  
Wide Range ◽  
Public And Private Sector

Abstract. Automated water sampling devices adapted to field operation have proven highly useful for environmental research as well as in the public and private sector, where natural or artificial waters need to be tested regularly for compliance with environmental and health regulations. Such autosamplers are already available on the market in slightly differing versions, but none of these devices are capable of sealing the collected samples to prevent sample alteration by contamination, evaporation or gas exchange. In many sampling cases, however, this feature is essential, for instance for studying the hydrological cycle based on isotopes in rainwater, or for monitoring waters contaminated with toxic gases or other volatile compounds detrimental to biota and human health. Therefore, we have developed a new mobile autosampler, which injects water samples directly into airtight vials, thus preventing any sample alteration. Further advantages include low production costs, compact dimensions and low weight allowing for easy transport, a wide range of selectable sampling intervals as well as a low power consumption, which make it suitable for long-term applications even in remote areas and harsh (outdoor) conditions due to its heavy-duty water-proof casing. In this paper, we demonstrate (1) the sampler's mechanical functioning, (2) the long-term stability of the collected samples with regard to evaporation and gas exchange and (3) the potential of our device in a wide variety of applications drawing on laboratory and field experiments in different karst caves, which represent one of the most challenging sampling environments.

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