128 research outputs found

    Stem emissions of monoterpenes, acetaldehyde, and methanol from Scots pine (Pinus sylvestris L.) affected by tree water relations and cambial growth

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    Abstract Tree stems are an overlooked source of volatile organic compounds (VOCs). Their contribution to ecosystem processes and total VOC fluxes is not well studied, and assessing it requires better understanding of stem emission dynamics and their driving processes. To gain more mechanistic insight into stem emission patterns, we measured monoterpene, methanol, and acetaldehyde emissions from the stems of mature Scots pines (Pinus sylvestris L.) in a boreal forest over three summers. We analysed the effects of temperature, soil water content, tree water status, transpiration, and growth on the VOC emissions, and used generalized linear models to test their relative importance in explaining the emissions. We show that Scots pine stems are considerable sources of monoterpenes, methanol, and acetaldehyde, and their emissions are strongly regulated by temperature. However, even small changes in water availability affected the emission potentials: increased soil water content increased the monoterpene emissions within a day, whereas acetaldehyde and methanol emissions responded within two to four days. This lag corresponded to their transport time in the xylem sap from the roots to the stem. Moreover, the emissions of monoterpenes, methanol, and acetaldehyde were influenced by the cambial growth rate of the stem with six- to ten-day lags. This article is protected by copyright. All rights reserved.Peer reviewe

    Predictive analytics in facilities management: A pilot study for exploring environmental comfort using wireless sensors

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    Purpose: Advancements in wireless sensor technology and building modelling techniques have enabled facilities managers to understand the environmental performance of the workplace in more depth than ever before. However, it is unclear to what extent this data can be used to predict subjective environmental comfort. Thus, the aim of this study was to pilot test a methodological framework for integrating real-time environmental data with subjective ratings of environmental comfort. Design/Methodology/Approach: An open-plan office was fitted with environmental sensors to measure key indoor environmental quality parameters (carbon dioxide, temperature, humidity, illumination, and sound pressure level). Additionally, building modelling techniques were used to calculate two spatial metrics (‘workspace integration’ and workspace density) for each workspace within the study area. 15 employees were repeatedly sampled across an 11-day study period, providing 78 momentary assessments of environmental comfort. Multilevel models were used to explore the extent to which the objective environmental data predicted subjective environmental comfort. Findings: Higher carbon dioxide levels were associated with more negative ratings of air quality, higher ‘workspace integration’ was associated with higher levels of distractions, and higher workspace density was associated with lower levels of social interactions. Originality/Value: To our knowledge, this is the first field study to directly explore the relationship between physical environment data collected using wireless sensors and subjective ratings of environmental comfort. The study provides proof-of-concept for a methodological framework for the integration of building analytics and human analytics

    An evidence-based assessment of the past distribution of Golden and White-tailed Eagles across Wales

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    Two species of eagles (Golden and White‐tailed) bred in Wales during prehistoric and historic times and became regionally extinct as breeding species in the mid‐1800s. They are iconic and charismatic, and discussions about reintroducing them back into the Welsh landscape have been ongoing for years. Reintroductions, however, can be risky, costly and/or contentious. To address these concerns, and to judge whether it is appropriate to reintroduce a regionally extinct species; the “International Union for Conservation of Nature (IUCN)” have produced criteria by which a proposed reintroduction can be assessed. A key criterion is that the potential reintroduction location lies within the former range of the species. In this study, we addressed this criterion by assessing the past distributions of Golden and White‐tailed Eagles within Wales. Using historic observational data, fossil/archaeological records and evidence from place‐names in the Welsh language, we demonstrated strong evidence for the presence of both of these eagle species in Wales in pre‐historic and historic times. We used kernel density functions to model the likely core distributions of each species within Wales. The resulting core distributions encompassed much of central and west‐north Wales for both species, with the White‐tailed Eagle exhibiting a wider core distribution extending into south Wales. Our results fill knowledge gaps regarding the historic ranges of both species in Britain, and support the future restoration of either or both species to Wales

    Effect of temperature on pollen germination for several Rosaceae species: influence of freezing conservation time on germination patterns

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    [EN] Between February 2018 and April 2018, flowers were collected from eight Rosaceae species. Flowers were kept in a freezer at -20 degrees C for three freezing times (Treatment 1, two months; Treatment 2, four months; Treatment 3, six months). After extracting pollen, in vitro germination was induced in a culture medium and incubated at six different temperatures for 72 h. The percentage of pollen germination, average pollen tube length and maximum pollen tube length were measured. Pollen germination was maximum for all species between 15 degrees C and 30 degrees C. Cydonia oblonga, Malus sylvestris, Prunus avium, Prunus domestica, Prunus dulcis, Prunus persica and Pyrus communis obtained 30-52% pollen germination between 15 degrees C and 20 degrees C. Prunus cerasifera had 40% pollen germination at 30 degrees C. All species studied reached the maximum pollen tube length between 10 degrees C and 25 degrees C. Germination did not change significantly for any of the species with freezing time, but we found significant differences in the three parameters measured between treatments. The highest germination percentages were obtained in Treatment 2 (four months frozen at -20 degrees C), while the maximum pollen tube length was reached in Treatment 1 (two months frozen at -20 degrees C). According to our results, freezing time affected the germination-temperature patterns. This could indicate that studies on the effect of temperature on pollen germination should always be carried out with fresh pollen to obtain more conclusive data.This work was supported by the Asociacion Club de Variedades Vegetales Protegidas as a part of a project with the Universitat Politecnica de Valencia (UPV 20170673). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.BeltrĂĄn, R.; Valls, A.; CebriĂĄn, N.; Zornoza, C.; GarcĂ­a-Breijo, F.; Reig Armiñana, J.; Garmendia, A.... (2019). Effect of temperature on pollen germination for several Rosaceae species: influence of freezing conservation time on germination patterns. PeerJ. 7:1-18. https://doi.org/10.7717/peerj.8195S1187Acar, I., & Kakani, V. G. (2010). The effects of temperature on in vitro pollen germination and pollen tube growth of Pistacia spp. Scientia Horticulturae, 125(4), 569-572. doi:10.1016/j.scienta.2010.04.040Boavida, L. C., & McCormick, S. (2007). TECHNICAL ADVANCE: Temperature as a determinant factor for increased and reproducible in vitro pollen germination in Arabidopsis thaliana. The Plant Journal, 52(3), 570-582. doi:10.1111/j.1365-313x.2007.03248.xBrewbaker, J. L., & Kwack, B. H. (1963). THE ESSENTIAL ROLE OF CALCIUM ION IN POLLEN GERMINATION AND POLLEN TUBE GROWTH. American Journal of Botany, 50(9), 859-865. doi:10.1002/j.1537-2197.1963.tb06564.xBurke, J. J., Velten, J., & Oliver, M. J. (2004). In Vitro Analysis of Cotton Pollen Germination. Agronomy Journal, 96(2), 359-368. doi:10.2134/agronj2004.3590CastĂšde, S., Campoy, J. A., GarcĂ­a, J. Q., Dantec, L., Lafargue, M., Barreneche, T., 
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    Longitudinal maturation of auditory cortical function during adolescence

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    Cross-sectional studies have demonstrated that the cortical auditory evoked potential (CAEP) changes substantially in amplitude and latency from childhood to adulthood, suggesting that these aspects of the CAEP continue to mature through adolescence. However, no study to date has longitudinally followed maturation of these CAEP measures through this developmental period. Additionally, no study has examined the trial-to-trial variability of the CAEP during adolescence. Therefore, we longitudinally tracked changes in the latency, amplitude, and variability of the P1, N1, P2, and N2 components of the CAEP in 68 adolescents from age 14 years to age 17 years. Latency decreased for N1 and N2, and did not change for P1 or P2. Amplitude decreased for P1 and N2, increased for N1, and did not change for P2. Variability decreased with age for all CAEP components. These findings provide longitudinal support for the view that the human auditory system continues to mature through adolescence. Continued auditory system maturation through adolescence suggests that CAEP neural generators remain plastic during this age range and potentially amenable to experience-based enhancement or deprivation
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