Irreversible diameter change of wood segments correlates with other methods for estimating frost tolerance of living cells in freeze-thaw experiment: a case study with seven urban tree species in Helsinki

International audienceAbstractKey messageWe assessed tree frost tolerance using electrolyte leakage and a method based on irreversible diameter change of branches. It was shown that irreversible diameter change correlates with electrolyte leakage and USDA hardiness rating and is a good indicator of frost tolerance.ContextThe number of potential tree species for urban green planning is low in northern latitudes where cold tolerance is a critical factor. High cost of urban tree establishment calls for reliable and preferably non-destructive methods for determining their cold tolerance.AimsWe studied the cellular damage occurring during freezing and thawing in branches of seven broadleaved tree species using electrolyte leakage and a method based on branch diameter changes.MethodsCellular damage in branches was studied during the cold-hardy stage in winter and the dehardening stage in early spring in laboratory conditions using both monitoring of frost-induced diameter changes and the common electrolyte leakage method during temperature decrease to −25 °C.ResultsFrost-induced irreversible diameter shrinkage correlated positively with electrolyte leakage. Out of the seven studied species, Quercus palustris and Crataegus monogyna had the highest frost tolerance during the dehardening stage in early spring, whereas Pterocarya fraxinifolia was the least frost tolerant.ConclusionIrreversible shrinkage of branch diameter due to freezing stress is a good and non-destructive method to indicate frost tolerance. It also correlates well with the USDA plant hardiness rating that is based on the minimum temperature range in which the studied species prevail in the USA

Differences Between Familial and Sporadic Celiac Disease

Background It is not known if genetic background, characteristics at diagnosis, physical and psychological well-being, and adherence to a gluten-free diet are comparable between patients with familial or sporadic celiac disease. These issues were investigated in a follow-up study. Methods Altogether 1064 patients were analyzed for celiac disease-associated serology, predisposing HLA-DQ, and non-HLA genotypes. Medical data were collected from patient records and supplementary interviews. Current symptoms and quality of life were further evaluated with the Gastrointestinal Symptom Rating Scale (GSRS), the Psychological General Well-Being questionnaire (PGWB), and Short Form 36 (SF-36) questionnaires. Results Familial and sporadic groups differed (P <0.001) in the reason for diagnosis and clinical presentation at diagnosis, familial patients being more often screen-detected (26% vs. 2%,P <0.001) and having less often gastrointestinal (49% vs. 69%) and severe symptoms (47% vs. 65%). The groups were comparable in terms of histological damage, frequency of malabsorption, comorbidities, childhood diagnoses, and short-term treatment response. At the time of the study, familial cases reported fewer symptoms (21% vs. 30%,P = 0.004) and lower prevalence of all (78% vs. 86%,P = 0.007), neurological (10% vs. 15%,P = 0.013), and dermatological (9% vs. 17%,P = 0.001) comorbidities. Dietary adherence and GSRS scores were comparable, but familial cases had better quality of life according to PGWB and SF-36. High-risk genotype HLA-DQ2.5/DQ2.5 was more frequent among familial cases, and four non-HLA SNPs were associated with familial celiac disease. Conclusions Despite the greater proportion of high-risk genotypes, familial cases had milder symptoms at presentation than did sporadic cases. Worse experience of symptoms and poorer quality of life in sporadic disease indicate a need for intensified support.Peer reviewe

Tree Water Status Affects Tree Branch Position

Physiological processes cause movements of tree stems and branches that occur in a circadian rhythm and over longer time periods, but there is a lack of quantitative understanding of the cause-and-effect relationships. We investigated the movement of tree branches in a long-term drought experiment and at a circadian time scale using time-series of terrestrial laser scanning measurements coupled with measurements of environmental drivers and tree water status. Our results showed that movement of branches was largely explained by leaf water status measured as leaf water potential in a controlled environment for both measured trees (R2 = 0.86 and R2 = 0.75). Our hypothesis is that changes in leaf and branch water status would cause branch movements was further supported by strong relationship between vapor pressure deficit and overnight branch movement (R2 = [0.57–0.74]). Due to lower atmospheric water demand during the nighttime, tree branches settle down as the amount of water in leaves increases. The results indicate that the quantified movement of tree branches could help us to further monitor and understand the water relations of tree communities

Tree Water Status Affects Tree Branch Position

Physiological processes cause movements of tree stems and branches that occur in a circadian rhythm and over longer time periods, but there is a lack of quantitative understanding of the cause-and-effect relationships. We investigated the movement of tree branches in a long-term drought experiment and at a circadian time scale using time-series of terrestrial laser scanning measurements coupled with measurements of environmental drivers and tree water status. Our results showed that movement of branches was largely explained by leaf water status measured as leaf water potential in a controlled environment for both measured trees (R2 = 0.86 and R2 = 0.75). Our hypothesis is that changes in leaf and branch water status would cause branch movements was further supported by strong relationship between vapor pressure deficit and overnight branch movement (R2 = [0.57–0.74]). Due to lower atmospheric water demand during the nighttime, tree branches settle down as the amount of water in leaves increases. The results indicate that the quantified movement of tree branches could help us to further monitor and understand the water relations of tree communities

Silver birch ability to refill fully embolised xylem conduits under tension

Peer reviewe

Koulunkäynti, opetus ja hyvinvointi kouluyhteisössä koronaepidemian aikana : Tuloksia syksyn 2020 aineistonkeruusta

Tämä väliraportti esittelee syksyllä 2020 toteutetun kyselytutkimuksen tuloksia. Syksyn aineistonkeruu on osa keväällä 2020 käynnistettyä valtakunnallista tutkimushanketta, jossa selvitetään koronapandemian vaikutuksia koulunkäyntiin, opetukseen sekä oppilaiden, huoltajien ja koulun henkilökunnan hyvinvointiin. Tutkimusta toteuttavat yhteistyössä Helsingin ja Tampereen yliopistot. Raportti on muodostettu teemoittain siten, että kunkin teeman yhteyteen on koottu teemaa koskevat tulokset usean eri vastaajaryhmän osalta. Syksyn aineistonkeruu toteutettiin marraskuun 2020 aikana. Aineistonkeruun ensimmäinen kierros oli 9.-22.11.2020. Kouluille, jotka eivät tänä aikana olleet vastanneet, lähetettiin muistutusviesti ja heille annettiin mahdollisuus osallistua tutkimukseen 24.-30.11.20. Kuten keväällä, aineistoa kerättiin samanaikaisesti viideltä eri vastaajaryhmältä (oppilaat, huoltajat, opettajat, rehtorit sekä oppilashuoltohenkilöstö ja koulun muu henkilöstö). Tarkempia tietoja vastaajaryhmittäin on koottu seuraavalle sivulle. Tutkimuksen tulokset on raportoitu pääosin eri vastaajaryhmien vastauksia esittävinä jakaumina. Kuvaukset aineiston analyysissa käytetyistä monimutkaisemmista tilastollisista menetelmistä löytyvät raportin lopussa olevasta menetelmäliitteestä

Koulunkäynti, opetus ja hyvinvointi kouluyhteisössä koronaepidemian aikana: tuloksia kevään 2021 aineistonkeruusta : Väliraportti syksy 2021

Valtakunnallinen Koulunkäynti, opetus ja hyvinvointi kouluyhteisössä koronaepidemian aikana -tutkimushanke käynnistyi keväällä 2020 opetus- ja kulttuuriministeriön toimeksiannosta. Tampereen yliopiston ja Helsingin yliopiston yhteistyössä toteuttaman tutkimuksen puitteissa on toteutettu nyt yhteensä kolme valtakunnallista aineistonkeruuta: toukokuussa 2020, marraskuussa 2020 sekä huhti-toukokuussa 2021. Kussakin aineistonkeruussa pandemian vaikutuksia on kysytty erikseen viideltä eri vastaajaryhmältä: oppilailta, opettajilta, rehtoreilta, oppilashuoltohenkilökunnalta sekä oppilaiden huoltajilta. Tämä väliraportti esittelee tutkimuksen tuloksia erityisesti kevään 2021 aineistonkeruukierrokselta. Lisäksi raportti sisältää kootusti seurantatietoja koko tutkimushankkeen ajalta. Raportin rakenne on seuraava: OSA 1 KESKEISET TULOKSET JA TOIMENPIDESUOSITUKSET OSA 2 TUTKIMUSRAPORTTI OSA 3 VALMISTEILLA OLEVAT TIETEELLISET JULKAISU

Low apoplastic water potential in trees : dehydration stress on living cells and embolism in xylem

Low apoplastic water potentials can affect trees by decreasing the hydraulic conductivity of xylem due to embolism and by causing dehydration stress in living cells. Low apoplastic water potentials regularly occur in trees during summer and winter. These can either be caused by loss of water due to transpiration or by freezing due to the chemical properties of ice. In this thesis the effects of low apoplastic water potential on trees were studied by causing low water potentials with three different methods: desiccation, freezing and by adjusting the osmotic concentration of xylem sap. Tree responses in this thesis were measured with stem diameter changes, leaf gas exchange, tree temperature and xylem water potential. Living parenchyma cells are thought to have negligible effect on xylem diameter changes but this thesis shows that the role of parenchyma can, in fact, be much more significant. Evidence for the major role of parenchyma cells in the diameter changes of frozen xylem also supported the theory of extracellular freezing. Furthermore, mesophyll cells were shown to react to freezing with a rapid depression of photosynthesis. It was also studied how a pressure increase in the xylem conduits, resulting from low water potentials, affects tree water relations during embolism formation and ice propagation. A gas burst was detected emerging from the tree stem during freezing. A decrease in the amount of gases in the xylem conduit can benefit trees in avoiding winter embolism. It was also experimentally confirmed that the formation of embolism in trees can temporarily even help relieve water stress due to the so called ´capacitive effect´. Low apoplastic water potential affects both the xylem and living cells in trees, and the interconnectedness of these responses are also shown in this thesis

A 21st Century Breakdown? The Development of Capital Market Anomalies and Market Turnover in Finland

This thesis studies the existence and development of capital market anomalies in Finland during the 21st century. In theory, factors that reduce trading frictions should lead to more efficient markets and thus attenuating anomaly returns. I study whether the changes in market turnover has the kind of effect on seven capital market anomalies. Three of the seven anomalies are statistically significant during the time period. I do not find evidence of the anomalies decreasing over time. Furthermore, I find that the market turnover in Finland has had a negative trend during the 21st century. I find weak evidence of anomalies having an inverse trend with market turnover and by using the quantile regression method I find more extreme values of the anomalies having a stronger reaction to changes in market turnover