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Exploring the physiological, neurophysiological and cognitive performance effects of elevated carbon dioxide concentrations indoors
Rationale: An accumulation of CO2 in occupied indoor spaces is correlated to negative impacts on
concentration, sleepiness and aspects of cognitive performance. However factors such as: (a) the
relative effect of CO2 itself compared to other pollutants; (b) the minimum necessary exposure time
for cognitive performance to be affected; and (c) the physiological drivers of cognitive performance
reductions due to increased indoor CO2 concentrations are not yet clear. Method: A within-subjects
counterbalanced study design was used to test cognitive performance, subjective and physiological
parameters of 31 volunteers during short (< 40 minutes) exposures to normal CO2 (830 ppm) and high
CO2 (2,700 ppm, raised by introducing pure CO2 alongside the occupant generated CO2). The study
was conducted in a small naturally ventilated office and EEG was used as an objective indicator of
sleepiness. Results: The addition of pure CO2 to the room resulted in the absence of an expected
learning effect in two cognitive performance test battery components without measurably affecting
any of the physiological, psychological, or reported comfort, sick building syndrome and health
variables measured. However participants who had slept less the previous night appeared more
susceptible to becoming sleepier as a result of the increased CO2. Contributions: The results suggest
(1) the addition of pure CO2 may influence aspects of cognitive performance after only short
exposures (2) these changes occur in the absence of clear physiological drivers, (3) lack of sleep may mediate people鈥檚 response to higher CO2 concentration
Effect of Water Activity on the Major Volatile? Produced in a Model System Approximating Cooked Meat
Seed vigor testing: an overview of the past, present and future perspective
The assessment of seed vigor has many important implications to the seed industry as a basic monitoring of seed physiological potential during different phases of seed production and a support for strategic decisions regarding the selection of high quality seedlots to meet the consumer demand. The potential attributes of seed vigor as a fundamental physiological seed characteristic and its association with field stand establishment and crop productivity has been worldwide recognized from the 1960s onward. This led to the diversification of research approaches involving the synchronization of different physiological characteristics and events that determine the potential for high performance during seed storage and after sowing. The basic objective of vigor testing is to provide a consistent identification of differences in physiological potential among seedlots of commercial value and this represents a more sensitive parameter than the germination test. There are various procedures to assess seed vigor including those that directly or indirectly evaluate seed metabolic state or identify seed tolerance to specific stress(es). At the same time, in more recent years, new knowledge has come from molecular biology, biotechnology, biophysics and seed and seedling imaging analyses; these approaches has been important complements to traditional seed research.. This text has the purpose to emphasize the role of Brazilian research in seed vigor, whose competence is internationally recognized, and to provide an overview of the evolution of knowledge also attempting to highlight events that contributed to the advancement of research on the subject