Gemeten actuele verdamping voor twaalf locaties in Nederland

Stowa heeft Alterra de opdracht gegeven jaarreeksen van actuele dagelijkse verdamping af te leiden voor twaalf meetlocaties in Nederland. Daarbij is gebruik gemaakt van bestaande (micro)meteorologische meetgegevens. De meetgegevens zijn gecontroleerd op kwaliteit en continuïteit en ontbrekende dagtotalen zijn aangevuld met door een Artificieel Neuraal Netwerk gesimuleerde gegevens. De onzekerheid in de jaartotalen van de bepaalde actuele verdamping ligt tussen de 10 en 15%

Use of a mobile platform for assessing urban heat stress in Rotterdam

In this study, an assessment of the intensity of the urban heat island (UHI) in Rotterdam was carried out using an innovative mobile bio-meteorological measuring platform mounted on a cargo bicycle. The goal was to assess whether or not heat stress is currently or likely to become a critical issue. Physiological equivalent temperatures were calculated directly from the measurements. Preliminary results show how effective urban parks and greenery are in reducing the UHI. The maximum UHI was about 7 K warmer than the rural area, whereas greener urban configurations were under 3 K warmer. City parks show marked cooling effects during daytime. The preliminary results clearly demonstrate the presence of a considerable UHI in Rotterdam, which is expected to be found in other Dutch cities, and confirms the important role of green spaces in mitigating urban heat stress

Verdamping van kale grond in de winter

Traditioneel is door hydrologen en micrometeorologen aan verdamping in de zomer meer aandacht gegeven dan aan verdamping in de winter. Dit is te verklaren uit het grote belang dat de landbouw heeft bij het juist voorspellen van vochttekorten in de zomer in verband met mogelijke opbrengstdalingen. De winter is echter de belangrijkste periode voor aanvulling van grondwater. Bovendien bepaalt de hydrologische balans van de winter in hoge mate de voorjaarsgrondwaterstand, die weer grote invloed heeft op het mogelijke voorkomen van plantensoorten in de natuur. Daarnaast geven berekeningen met regionale hydrologische modellen in de winter vaak een te hoge afvoer te zien. Een van de mogelijke redenen hiervoor is dat de verdamping tijdens de winterperiode onderschat word

Hydrologie en waterhuishouding van bosgebieden in Nederland; fase 2: meetopzet en eerste resultaten

Verdampings-, voelbarewarmte- en impulsflux, bodemvochtgehalte, weervariabelen en doorval zijn op vier boslocaties (populier, lariks, grove den, gemengd naald- en loofbos) in 1995 nagenoeg continu gemeten. In de zomer nam het interceptieverlies als percentage van de brutoneerslag af in de volgorde lariks (32,2%), populier (26,7%) en grove den (21,5%). De transpiratie nam af in de volgorde populier (422 mm), lariks (375 mm) en grove den (283 mm). Dit is een eerste schatting uit de metingen van de totale verdamping en interceptie voor het groeiseizoen van dag 120 tot en met dag 275. Het totale waterverbruik van populier (655 mm) en lariks (651 mm) is vrijwel gelijk, en hoger dan dat van grove den (539 mm)

De waterbalans van grove den op de Veluwe 1995

De interceptiepercentages van douglasspar zijn twee keer zo hoog als in 1995 voor grove den is gemeten. De transpiratie voor grove den is 100 mm lager dan die berekend voor douglasspar. Verlovingsscenarios voor de Veluwe, waarbij de totale oppervlaktewordt verondersteld uit douglasspar te bestaan, geven dus een vertekend beeld van de regionale waterbalans. Het verdampingsverlies van grove den komt meer overeen met dat van eikenbos. De verdamping van drie opstanden populieren, grove den en lariks verschilt nauwelijks in de winter van 1995. In de hydrologisch belangrijke winterperiode zal er weinig verschil in de grondwatertoelevering van deze drie opstanden bestaan

Net ecosystem exchange of carbon dioxide and water of far eastern Siberian Larch (Larix cajanderii) on permafrost.

Observations of the net ecosystem exchange of water and CO₂ were made during two seasons in 2000 and 2001 above a Larch forest in Far East Siberia (Yakutsk). The measurements were obtained by eddy correlation. There is a very sharply pronounced growing season of 100 days when the forest is leaved. Maximum half hourly uptake rates are 18 &micro;mol m^-2 s^-1; maximum respiration rates are 5 &micro;mol m^-2 s^-1. Net annual sequestration of carbon was estimated at 160 gCm^-2 in 2001. Applying no correction for low friction velocities added 60 g C m^-2. The net carbon exchange of the forest was extremely sensitive to small changes in weather that may switch the forest easily from a sink to a source, even in summer. June was the month with highest uptake in 2001. <P style='line-height: 20px;'> The average evaporation rate of the forest approached 1.46 mm day^-1 during the growing season, with peak values of 3 mm day^-1 with an estimated annual evaporation of 213 mm, closely approaching the average annual rainfall amount. 2001 was a drier year than 2000 and this is reflected in lower evaporation rates in 2001 than in 2000. <P style='line-height: 20px;'> The surface conductance of the forest shows a marked response to increasing atmospheric humidity deficits. This affects the CO₂ uptake and evaporation in a different manner, with the CO₂ uptake being more affected. There appears to be no change in the relation between surface conductance and net ecosystem uptake normalized by the atmospheric humidity deficit at the monthly time scale. The response to atmospheric humidity deficit is an efficient mechanism to prevent severe water loss during the short intense growing season. The associated cost to the sequestration of carbon may be another explanation for the slow growth of these forests in this environment

Diagnostic Value of Microbial Cell-free DNA Sequencing for Suspected Invasive Fungal Infections:A Retrospective Multicenter Cohort Study

Background: An early diagnosis and treatment of invasive fungal disease (IFD) is associated with improved outcome, but the moderate sensitivity of noninvasive diagnostic tests makes this challenging. Invasive diagnostic procedures such as bronchoalveolar lavage (BAL) have a higher yield but are not without risk. The detection and sequencing of microbial cell-free DNA (mcfDNA) may facilitate a noninvasive diagnosis. Materials: In a prospective observational study, we collected plasma in the 120 hours preceding or following a BAL in patients with hematological malignancies suspected for a pulmonary IFD. The EORTC/MSGERC2020 criteria were used for IFD classification. Sequencing was performed by Karius (Redwood City, CA) using their Karius Test (KT) on plasma and a "research use only test"on BAL fluid if available. Cases with a probable/proven IFD were identified based on standard diagnostic tests on serum and BAL (microscopy, polymerase chain reaction, galactomannan, culture) and used to calculate the sensitivity, specificity, and additional diagnostic value of the KT. Results: Of 106 patients enrolled, 39 (37%) had a proven/probable invasive aspergillosis, 7 (7%) a non-Aspergillus IFD, and 4 (4%) a mixed IFD. The KT detected fungal mcfDNA in 29 (28%) patients. Compared with usual diagnostic tests, the sensitivity and specificity were 44.0% (95% confidence interval [CI], 31.2-57.7) and 96.6% (95% CI, 88.5%-99.1%). Sensitivity of the KT was higher in non-Aspergillus IFD (Mucorales:2/3, Pneumocystis jirovecii: 3/5). On BAL, the sensitivity was 72.2% (95% CI, 62.1-96.3), and specificity 83.3% (95% CI, 49.1-87.5). Conclusions: Sequencing of mcfDNA may facilitate a noninvasive diagnosis of IFD in particular non-Aspergillus IFD. However, on plasma and similar to currently available diagnostics, it cannot be used as a "rule-out"test.</p

Curved Tails in Polymerization-Based Bacterial Motility

The curved actin ``comet-tail'' of the bacterium Listeria monocytogenes is a visually striking signature of actin polymerization-based motility. Similar actin tails are associated with Shigella flexneri, spotted-fever Rickettsiae, the Vaccinia virus, and vesicles and microspheres in related in vitro systems. We show that the torque required to produce the curvature in the tail can arise from randomly placed actin filaments pushing the bacterium or particle. We find that the curvature magnitude determines the number of actively pushing filaments, independent of viscosity and of the molecular details of force generation. The variation of the curvature with time can be used to infer the dynamics of actin filaments at the bacterial surface.Comment: 8 pages, 2 figures, Latex2