UV-induced chlorophyll (ChlFUV) and blue-green (BGF) fluorescences emitted by leaves have been proposed as useful indicators of plant physiological status under stress conditions. In this report, we investigated the effects of nitrogen (N) deficiency on ChlFUV and BGF emissions of leaf sections in relation to plant growth inhibition and accumulation of phenolic metabolites in barley leaves. Plants in a growth chamber were supplied with one of five different NO3 concentrations (0.8, 1.6, 5.0, 8.0, or 16 mmol/L) for a 2-week period. Total fresh biomass decreased with decreasing N supply, whereas leaf content of soluble phenolic compounds increased. This increase in leaf phenolic compounds observed with limiting N supply was accompanied by large increases of the BGF intensity and BGF/ChlFUV ratio of leaf sections and, to a lower extent, by a decrease of the leaf epidermal transmittance of UV radiation (as estimated by the ratio of ChlF intensities induced by UV and blue excitation). Interestingly, we observed a negative correlation (r2 = 0.975) between fresh biomass of plants and BGF intensity of leaf sections. By interpreting, in a context of stress physiology, the changes of UV-induced fluorescences, our results support their potential use as a sensitive tool for the rapid assessment of a plant's nutrient status.Key words: blue-green fluorescence, chlorophyll fluorescence, flavonoids, growth inhibition, nitrogen deficiency, phenolic compounds.
Background: Skin and soft-tissue infections are very common among persons who inject drugs. They occur when microbes pass under the protective layer of the skin and proliferate. This happens when harm reduction recommendations such as skin aseptia before injection and sterile injection equipment usage are not properly followed.
IMPORTANCEGiven limited COVID-19 vaccine availability early in the pandemic, optimizing immunization strategies was of paramount importance. Ring vaccination has been used successfully to control transmission of other airborne respiratory viruses. OBJECTIVE To assess the association of a ring vaccination intervention on COVID-19 spread in the initial epicenter of SARS-CoV-2 Alpha variant transmission in Montreal, Canada. DESIGN, SETTING, AND PARTICIPANTS This cohort study compared COVID-19 daily disease risk in 3 population-based groups of neighborhoods in Montreal, Canada, defined by their interventionspecific vaccine coverage at the neighborhood level: the primary intervention group (500 or more vaccinated persons per 10 000 persons), secondary intervention group (95 to 499), and control group (0 to 50). The groups were compared within each of 3 time periods: before intervention
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