Search results for "LIGHT"
showing 10 items of 3575 documents
Diurnal and Seasonal Solar Induced Chlorophyll Fluorescence and Photosynthesis in a Boreal Scots Pine Canopy
2019
Solar induced chlorophyll fluorescence has been shown to be increasingly an useful proxy for the estimation of gross primary productivity (GPP), at a range of spatial scales. Here, we explore the seasonality in a continuous time series of canopy solar induced fluorescence (hereafter SiF) and its relation to canopy gross primary production (GPP), canopy light use efficiency (LUE), and direct estimates of leaf level photochemical efficiency in an evergreen canopy. SiF was calculated using infilling in two bands from the incoming and reflected radiance using a pair of Ocean Optics USB2000+ spectrometers operated in a dual field of view mode, sampling at a 30 min time step using custom written …
Validating an apple dry matter production model with whole canopy gas exchange measurements in the field
1999
The simplified apple dry matter production model developed by Lakso and Johnson (1990) was modified by inputing tree-specific parameters from a study of seasonal growth and gas exchange of 4-year-old Empire/M.9 apple trees, and light and temperature response curves developed for Empire apple organs. Measurements of the seasonal trend of diurnal net C02 and canopy water vapor exchange were made at intervals on three four-year-old 'Empire'/M.9 slender spindle apple trees in the orchard from 10 days after bloom until 25 days after harvest. The tree canopies were enclosed in clear plastic "balloon- type" chambers (similar to Corelli and Magnanini, 1993) that was monitored continuously for more …
Influence of row orientation on the canopy temperature of Sicilian vineyards
2021
Row orientation can have significant effects on grape quality as it directly affects the exposure of the fruits with indirect consequences on wine quality. In this study, a Flir i7 thermal camera was used to measure the temperature of both canopy sides of a ‘Sauvignon blanc’ vineyard trained to vertical shoot position and with north-south (NS) and east-west (EW) row orientations. Photosynthetically active radiation (PAR) measurements using a 0.8-m sensor bar were taken along with the thermal imaging camera measurements. Considering both row orientations, south and east canopy sides were those that intercepted the greatest radiant energy during the day, 57.7 and 47.5%, respectively. The EW r…
Bidirectional sun-induced chlorophyll fluorescence emission is influenced by leaf structure and light scattering properties : a bottom-up approach
2015
Abstract Sun-induced chlorophyll fluorescence (SIF) at leaf level is emitted in both upward and downward directions in the red and far-red part of the spectrum (650–850 nm) when a leaf is illuminated from the upper leaf surface. Hence, total SIF is represented by the sum of the upward and downward emission components. Nevertheless, the downward component of leaf SIF is often not considered despite that downward fluorescence yield (↓FY) can amount up to 40% of the total fluorescence yield (FYtot). Downward SIF is mainly emitted in the far-red, since this part of fluoresced light is highly scattered within leaves, unlike red Chl fluorescence, which is mostly reabsorbed. While total FY can be …
Manganese carbonyl terpyridyl complexes: their synthesis, characterization and potential application as CO-release molecules
2014
MnI carbonyl terpyridyl complexes have been synthesized and characterized. The tricarbonyl derivative exhibits interesting behaviors for controlled CO-release by both thermal and photosynthetic pathways.
Reconstitution of bacteriorhodopsin and ATP synthase from Micrococcus luteus into liposomes of the purified main tetraether lipid from Thermoplasma a…
1995
The archaebacterium Thermoplasma acidophilum is cultivated at 59 degrees C in a medium containing sulfuric acid of pH 2. The purified bipolar membrane spanning main phospholipid (MPL) of this organism can be used to produce stable liposomes of 100-500 nm in diameter either using a French pressure cell detergent dialysis or sonication. Despite a potassium diffusion potential of 186 mV very low ionic permeability of sonicated MPL liposomes was measured using the potassium binding fluorescent indicator benzofuran isophthalate PBF1, which measures net K+ uptake. The latter also remained very low, in the presence of the K(+) ionophore valinomycin and palmitic acid. Addition of valinomycin and th…
Human HepG2 and rat Fao hepatic-derived cell lines show different responses to ciprofibrate, a peroxisome proliferator: analysis by flow cytometry.
1996
Abstract Peroxisome proliferators, and especially hypolipidemic drugs such as ciprofibrate, are known to be hepatocarcinogens in rodents, but their effect in humans is controversial. In an attempt to investigate the effects of ciprofibrate at a cellular level, the analysis of individual whole cells was performed by flow cytometry on samples from two hepatic-derived cell lines: the rat Fao cell line and the human HepG2 cell line. The increase of light scatter signals in rat Fao cells treated for 3 days with ciprofibrate at 250 μMwas related to modifications of intrinsic cellular parameters, such as size and cytoplasmic granularity. Conversely, no variations appeared in human HepG2-treated ce…
ChemInform Abstract: A Light-Induced Vinylogous Nazarov-Type Cyclization.
2016
The title reaction is incorporated in a three-step cascade transformation providing novel tetracyclic ring structures containing a seven-membered ring.
Gradientu pastiprināšanas algoritmu salīdzinājums un mainīgo būtiskuma analīze
2020
Šajā darbā tiek izpētīti un salīdzināti trīs no jaunākiem un plaši izmantotiem gradienta pastiprināšanas algoritmiem - XGBoost, LightGBM un CatBoost. Šie algoritmi tiek salīdzināti pēc to ātrdarbības, kā arī tendences uz pārpielāgošānos treniņa datiem. Tiek analizēta arī šo algoritmu spēja izmantot modelēšanā kategoriskus mainīgos. Papildus tiek izpētīti algoritmu hiperparametri un to ietekme uz algoritma pārpielāgošanos un modeļa precizitātes rādītājiem. Balstoties uz rezultātiem, tiek sniegti ieteikumi par hiperparametru skaņošanu. Otrajā eksperimenta daļā tiek izpētīta uz spēļu teorijas Šaplī vērtību balstītā metode mainīgo būtiskuma noteikšanai. Iegūtiem rādītājiem ar būtstrapa metodes …
Near-infrared imaging and structured light ranging for automatic catheter insertion
2006
Vein localization and catheter insertion constitute the first and perhaps most important phase of many medical procedures. Currently, catheterization is performed manually by trained personnel. This process can prove problematic, however, depending upon various physiological factors of the patient. We present in this paper initial work for localizing surface veins via near-infrared (NIR) imaging and structured light ranging. The eventual goal of the system is to serve as the guidance for a fully automatic (i.e., robotic) catheterization device. Our proposed system is based upon near-infrared (NIR) imaging, which has previously been shown effective in enhancing the visibility of surface vein…