Meta-analysis of the detection of plant pigment concentrations using hyperspectral remotely sensed data

Passive optical hyperspectral remote sensing of plant pigments offers potential for understanding plant ecophysiological processes across a range of spatial scales. Following a number of decades of research in this field, this paper undertakes a systematic meta-analysis of 85 articles to determine whether passive optical hyperspectral remote sensing techniques are sufficiently well developed to quantify individual plant pigments, which operational solutions are available for wider plant science and the areas which now require greater focus. The findings indicate that predictive relationships are strong for all pigments at the leaf scale but these decrease and become more variable across pigment types at the canopy and landscape scales. At leaf scale it is clear that specific sets of optimal wavelengths can be recommended for operational methodologies: total chlorophyll and chlorophyll a quantification is based on reflectance in the green (550–560nm) and red edge (680–750nm) regions; chlorophyll b on the red, (630–660nm), red edge (670–710nm) and the near-infrared (800–810nm); carotenoids on the 500–580nm region; and anthocyanins on the green (550–560nm), red edge (700–710nm) and near-infrared (780–790nm). For total chlorophyll the optimal wavelengths are valid across canopy and landscape scales and there is some evidence that the same applies for chlorophyll a

Sequential application of hyperspectral indices for delineation of stripe rust infection and nitrogen deficiency in wheat

© 2015, Springer Science+Business Media New York. Nitrogen (N) fertilization is crucial for the growth and development of wheat crops, and yet increased use of N can also result in increased stripe rust severity. Stripe rust infection and N deficiency both cause changes in foliar physiological activity and reduction in plant pigments that result in chlorosis. Furthermore, stripe rust produce pustules on the leaf surface which similar to chlorotic regions have a yellow color. Quantifying the severity of each factor is critical for adopting appropriate management practices. Eleven widely-used vegetation indices, based on mathematic combinations of narrow-band optical reflectance measurements in the visible/near infrared wavelength range were evaluated for their ability to discriminate and quantify stripe rust severity and N deficiency in a rust-susceptible wheat variety (H45) under varying conditions of nitrogen status. The physiological reflectance index (PhRI) and leaf and canopy chlorophyll index (LCCI) provided the strongest correlation with levels of rust infection and N-deficiency, respectively. When PhRI and LCCI were used in a sequence, both N deficiency and rust infection levels were correctly classified in 82.5 and 55 % of the plots at Zadoks growth stage 47 and 75, respectively. In misclassified plots, an overestimation of N deficiency was accompanied by an underestimation of the rust infection level or vice versa. In 18 % of the plots, there was a tendency to underestimate the severity of stripe rust infection even though the N-deficiency level was correctly predicted. The contrasting responses of the PhRI and LCCI to stripe rust infection and N deficiency, respectively, and the relative insensitivity of these indices to the other parameter makes their use in combination suitable for quantifying levels of stripe rust infection and N deficiency in wheat crops under field conditions

A Belief System's Organization Based on a Computational Model of the Dynamic Context: First Approximation

In this article we present a model of organization of a belief system based on a set of binary recursive functions that characterize the dynamic context that modifies the beliefs. The initial beliefs are modeled by a set of two-bit words that grow, update, and generate other beliefs as the different experiences of the dynamic context appear. Reason is presented as an emergent effect of the experience on the beliefs. The system presents a layered structure that allows a functional organization of the belief system. Our approach seems suitable to model different ways of thinking and to apply to different realistic scenarios such as ideologies

THE SPECTRAL CONTRIBUTION OF CAROTENOIDS TO LIGHT ABSORPTION AND REFLECTANCE IN GREEN LEAVES

Absorbance and reflectance spectra in the visible and near infrared range of the spectrum, acquired for maple (Acer platanoides L.) leaves were studied. Standard deviation of absorbance spectra showed that in yellow to green leaves, with chlorophyll content at least up to 30 nmol/cm2, there is a spectral feature at 520 nm attributable to carotenoids. Reflectance around 520 nm also correlates closely with carotenoids content in yellow to green leaves. Thus, this spectral feature at 520 nm could be used as a measure of carotenoids content in green leaves and plants

Thermal-based modeling of coupled carbon, water, and energy fluxes using nominal light use efficiencies constrained by leaf chlorophyll observations

Recent studies have shown that estimates of leaf chlorophyll content (Chl), defined as the combined mass of chlorophyll a and chlorophyll b per unit leaf area, can be useful for constraining estimates of canopy light use efficiency (LUE). Canopy LUE describes the amount of carbon assimilated by a vegetative canopy for a given amount of absorbed photosynthetically active radiation (APAR) and is a key parameter for modeling land-surface carbon fluxes. A carbonenabled version of the remote-sensing-based two-source energy balance (TSEB) model simulates coupled canopy transpiration and carbon assimilation using an analytical submodel of canopy resistance constrained by inputs of nominal LUE (βn), which is modulated within the model in response to varying conditions in light, humidity, ambient CO2 concentration, and temperature. Soil moisture constraints on water and carbon exchange are conveyed to the TSEB-LUE indirectly through thermal infrared measurements of landsurface temperature. We investigate the capability of using Chl estimates for capturing seasonal trends in the canopy βn from in situ measurements of Chl acquired in irrigated and rain-fed fields of soybean and maize near Mead, Nebraska. The results show that field-measured Chl is nonlinearly related to βn, with variability primarily related to phenological changes during early growth and senescence. Utilizing seasonally varying βn inputs based on an empirical relationship with in situ measured Chl resulted in improvements in carbon flux estimates from the TSEB model, while adjusting the partitioning of total water loss between plant transpiration and soil evaporation. The observed Chl– βn relationship provides a functional mechanism for integrating remotely sensed Chl into the TSEB model, with the potential for improved mapping of coupled carbon, water, and energy fluxes across vegetated landscapes

The behaviour of repeat visitors to museums: Review and empirical findings

This study presents a theoretical and operational framework for analysing repeat visit to museums. Starting from the literature on repeat visit in tourism, the specificities of these cultural attractions are made explicit through a review of theoretical and applied works. Consistently with previous contributors, the paper suggests that the analysis of actual past behaviours has to be preferred to the one of attitudes. The application of proper econometric models is also remarked in order to put into account individual profiles. Information coming from three techniques is then used in an integrated way in order to provide a more comprehensive view of the phenomenon. Evidence from an ad hoc survey suggests the necessity to give a greater attention to perceived cultural value during the visit, promoting cultural events during the week and addressed to children, and taking care of those visitors that come from far places also through an integrated tourist supply. © 2013 Springer Science+Business Media Dordrecht

Estimating foliar nitrogen in Eucalyptus using vegetation indexes

ABSTRACT Nitrogen (N) has commonly been applied in Eucalyptus stands in Brazil and it has a direct relation with biomass production and chlorophyll content. Foliar N concentrations are used to diagnose soil and plant fertility levels and to develop N fertilizer application rates. Normally, foliar N is obtained using destructive methods, but indirect analyses using Vegetation Indexes (VIs) may be possible. The aim of this work was to evaluate VIs to estimate foliar N concentration in three Eucalyptus clones. Lower crown leaves of three clonal Eucalyptus plantations (25 months old) were classified into five color patterns using the Munsell Plant Tissue Color Chart. For each color, N concentration was determined by the Kjeldahl method and foliar reflectance was measured using a CI-710 Miniature Leaf Spectrometer. Foliar reflectance data were used to obtain the VIs and the VIs were used to estimate N concentrations. In the visible region, the relationship between N concentration and reflectance percentage was negative. The highest correlations between VIs and N concentrations were obtained by the Inflection Point Position (IPP, r = 0.97), Normalized Difference Red-Edge (reNDVI, r = 0.97) and Modified Red-Edge Normalized Difference Vegetation Index (mNDI, r = 0.97). Vegetation indexes on the red edge region provided the most accurate estimates of foliar N concentration. The reNDVI index provided the best N concentration estimates in leaves of different colors of Eucalyptus urophylla × grandis and Eucalyptus urophylla × urophylla (R2 = 0.97 and RMSE = 0.91 g kg−1)

Роль сугаммадекса при эндоваскулярных вмешательствах на сосудах головного мозга

Highlights. The article discusses the features of general anesthesia in patients with cerebrovascular diseases using the relaxant binding agent sugammadex.Aim. To evaluate the effectiveness of sugammadex in endovascular management of cerebrovascular diseases.Methods. The study included 57 patients who underwent endovascular treatment of cerebrovascular disease under general anesthesia. The experimental group included 29 patients who were injected with sugammadex - a selective relaxant binding agent for reversal of neuromuscular block induced by rocuronium. The comparison group included 28 patients who did not undergo decurarization (n = 13), or it was performed with neostigmine (n = 15). Acceleromyography was used to monitor the state of neuromuscular function.Result. Onset of action and duration of action of rocuronium at a dose of 0.9 mg/kg did not differ between the groups. The neuromuscular recovery time was 2.14 [1.67; 2.59] minutes after administration of sugammadex, compared with spontaneous 35.8 [31.5; 40.4] minutes and neostigmine-induced 22.1 [16.8; 27.3] minutes (p<0.001). No adverse or allergic reactions were noted after administration of the relaxant binding agent.Conclusion. Using a specific antidote sugammadex to eliminate the effect of rocuronium helps to restore neuromuscular function within 2–3 minutes and assess the neurological status of patients immediately after the endovascular treatment of cerebrovascular disease.Основные положения. В статье обсуждаются особенности проведения общей анестезии пациентам с сосудистыми заболеваниями головного мозга с использованием релаксант-связывающего агента сугаммадекса.Цель. Оценка эффективности сугаммадекса при эндоваскулярных вмешательствах на сосудах головного мозга.Материалы и методы. В исследование включены 57 пациентов, которым выполнено рентгенэндоваскулярное вмешательство на сосудах головного мозга в условиях общей анестезии. В исследуемую группу вошли 29 больных, которым вводили сугаммадекс – релаксант-связывающий агент рокурония. Группу сравнения составили 28 пациентов, которым декураризация не выполнена (n = 13) или проведена с помощью неостигмина (n = 15). Для контроля состояния нейромышечной функции использован метод акcелерометрического мониторинга.Результаты. Время начала действия и клиническая продолжительность действия рокурония в дозе 0,9 мг/кг не различались в группах. Время восстановления нейромышечной проводимости после введения сугаммадекса составило 2,14 [1,67; 2,59] мин в сравнении с 35,8 [31,5; 40,4] мин при спонтанном восстановлении и 22,1 [16,8; 27,3] мин при восстановлении, индуцированным неостигмином (p<0,001). Не зафиксировано каких-либо побочных и аллергических реакций после введения релаксант-связывающего агента.Заключение. Использование специфического антидота сугаммадекса для устранения эффекта рокурония позволяет в течение 2–3 мин полностью восстановить нейромышечное проведение и оценить неврологический статус пациентов сразу после окончания эндоваскулярного вмешательства на сосудах головного мозга

Temporal dynamics of spectral reflectance and vegetation indices during canola crop cycle in southern Brazil

ABSTRACT: The objective of this study was to characterize the variability of spectral reflectance and temporal profiles of vegetation indices associated with nitrogen fertilization, crop cycle periods, and weather conditions of the growing season in canola canopies in southern Brazil. An experiment was carried out during the 2013 and 2014 canola growing seasons at EMBRAPA Trigo, Passo Fundo, state of Rio Grande do Sul, Brazil. The experiment was conducted in a randomized block design with four replications. Five doses of nitrogen top dressing were used as treatments: 10, 20, 40, 80, and 160kg ha-1. Measurements were obtained with the spectroradiometer positioned above the canopy, to construct spectral reflectance curves for canola and establish temporal profiles for several vegetation indices (SR, NDVI, EVI, SAVI, and GNDVI). In addition, data on shoot dry matter were obtained and phenological stages were determined. The spectral reflectance curves of canola were reported to change with canopy growth and development. Temporal profiles of vegetation indices showed two maximum peaks, one before flowering and other after flowering. The indices SR, NDVI, EVI, SAVI, and GNDVI were able to characterize changes in the canola canopy over time, as a function of phenological phases, weather conditions, and nitrogen fertilization, throughout the development cycle. Plant growth and development, variations in crop management, and environmental conditions affect the spectral response of canola