freeze-thaw induced embolism

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Characteristics of ultrasonic acoustic emissions from walnut branches during freeze–thaw-induced embolism formation

Characteristics of ultrasonic acoustic emissions from walnut branches during freeze–thaw-induced embolism formation

severe freezing stress in winter, some plants have developed increased cold-hardiness through adaptive processes (Sakai and Larcher, 1987; Larcher, 1995). To survive in cold areas, plants have improved the cold- hardiness of their living cells. However, the effects of freezing on living cells are not the only stresses on plants. Freezethaw cycles also induce embolism in water conduits, disturbing the water uptake of above-ground tissues and thus causing serious problems (Pratt et al., 2005). Continuity of the water column is essential to carry water from roots to leaves (the cohesion–tension hypothesis; Dixon, 1914). However, embo- lism generated by the formation of gas bubbles in water con- duits breaks this continuity, resulting in failure of the water transport system. In the field, freezethaw-induced embolism is a common event and has been observed in many tree spe- cies during winter and early spring (Ewers, 1985; Sperry et al., 1988; Sperry and Sullivan, 1992; Lo Gullo and Salleo, 1993; Hacke and Sauter, 1995; Cochard et al., 1997; Améglio et al., 2002; McCulloh et al., 2011). The failure of the water trans- port system during winter might restrict the availability of water for the resumption of growth in spring. Therefore, it is thought that vulnerability to freezethaw-induced embolism is a key factor determining the geographical distribution of trees in cold areas (Langan et al., 1997; Pockman and Sperry, 1997; Mayr et al., 2003, 2006, 2014; Charrier et al., 2013).
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Ultrasonic acoustic emissions: freezing pattern and relation with cavitation and freeze-thaw induced embolism in woody species.

Ultrasonic acoustic emissions: freezing pattern and relation with cavitation and freeze-thaw induced embolism in woody species.

Ul- trasonic acoustic emissions: freezing pattern and relation with cavitation and freeze-thaw induced embolism in woody species.. Xylem International Meeting, Sep 2015, Bordeaux, France[r]

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Freeze-Thaw Stress: Effects of Temperature on Hydraulic Conductivity and Ultrasonic Activity in Ten Woody Angiosperms

Freeze-Thaw Stress: Effects of Temperature on Hydraulic Conductivity and Ultrasonic Activity in Ten Woody Angiosperms

Xylem embolism is a limiting factor for plant sur- vival and distribution (Choat et al., 2012; Charrier et al., 2013). Two major factors can induce embolism in the xylem of plants: drought and freeze stress. Freeze- thaw-induced embolism is caused by bubbles formed during freezing that then expand on thawing (Lemoine et al., 1999; Hacke and Sperry, 2001; Cruiziat et al., 2002; Tyree and Zimmermann, 2002). As wider conduits con- tain more gas and form larger bubbles, which expand at less negative tension, conduit diameter and xylem sap tension are critical for the formation of freeze-thaw- induced embolism (Davis et al., 1999; Pittermann and Sperry, 2003). Accordingly, Mayr and Sperry (2010) observed a loss of conductivity only when samples were under critical tension during thawing. Under drought stress, tension in the xylem sap increases the sensitivity to embolism generated by successive freeze-thaw cycles (Mayr et al., 2003, 2007).
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Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze–thaw cycles

Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze–thaw cycles

Eucalyptus sp. UEs were continuously detected during the temperature decrease ( Fig.  7 , Table  1 ), as reported in previous stud- ies ( Mayr et  al., 2007 ; Mayr and Sperry, 2010 ; Mayr and Zublasing, 2010 ). We assume that cavitation events (air bubble formation, a prerequisite for embolism formation) occurred during freezing due to ice-induced high Ψ gradients ( Sevanto et al., 2012 ) and caused UEs, according to Charrier et al. (2014a , 2015a ) and Ponomarenko et al. (2014) . Hacker and Neuner (2008) and Pramsohler et al. (2012) reported that ice propagation started from the nucleation point and spread along the sample with a higher longitudinal than radial speed, and Charrier et  al. (2015b) reported that cavitation events occur at the ice front. Although the spatial resolution of our images was too low to detect whether air bubbles were already formed within vessels, such bubbles have been observed previ- ously within conifer xylem ( Sucoff, 1969 ; Robson et al., 1988 ) and angiosperms leaves ( Ball et al., 2006 ).
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Freeze/Thaw cycle monitoring using multi-scale SMAP products and hydrothermal modeling over the Canadian tundra: Final Research Report 2015-2019.

Freeze/Thaw cycle monitoring using multi-scale SMAP products and hydrothermal modeling over the Canadian tundra: Final Research Report 2015-2019.

proposed approaches B and C (Fig. 12c and Fig. 12d), where TB gradually decreases from south to north. The problem of low TB values observed along the north-west coastline boundaries is also solved. Freeze/Thaw cycle monitoring for Umiujaq pixel using SMAP-L1C brightness temperature was validated using the field data from the installed probes. The probes recorded the physical temperature of the soil at 5cm depth hourly from August 23, 2015, to August 18, 2016, at five core sites. Probes sites are selected based on area representativeness (land cover, topography and soil texture). F/T classification produced from radiometer data collected during the two daily overpasses at 6 AM and 6 PM was validated using probe data recorded at the same time. For validation, stations with a sol temperature less than -1 degree Celsius or greater than 1 degrees Celsius at 6 PM or 6 AM were classified respectively as frozen or thawed. Between -1 and 1 degrees Celsius, the soil has been considered in F/T or T/F transition states (Wang et al. 2017). Table 4 summarizes the validation results of the estimated SMAP F/T states at the Umiujaq pixel against in situ F/T classification based on five soil temperature sensors installed in different locations (see table 1) in the ~36km SMAP pixel. The over level of agreement was calculated for ascending (A) and descending (D) overpasses using as input original brightness temperature (∆NPR) and corrected values with approaches A (∆NPR A ), B
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Using available time series of passive and active microwave to develop smap freeze/thaw algorithms adapted for the Canadian Subarctic.

Using available time series of passive and active microwave to develop smap freeze/thaw algorithms adapted for the Canadian Subarctic.

Index Terms— Passive Microwave, Freeze-Thaw, Frozen Soil, SMOS, Remote Sensing, 1. INTRODUCTION This study was conducted in the context of the SMAP (Soil Moisture Active and Passive) mission of NASA to be launch on November 2014 which includes both a Radiometer and a Synthetic Aperture Radar operating at L- band (1.20-1.41 GHz). This band is promising for Freeze/Thaw (F/T) monitoring. This wavelength penetrates well through the atmosphere, and hence the instrument probes the earth surface emissivity. In fact, SMAP will have the capability to make coincident measurements of surface emission and backscatter at L-band, and this frequency has
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Impact of water stress-induced embolism on bud survival in Populus nigra sprouts

Impact of water stress-induced embolism on bud survival in Populus nigra sprouts

Barigah TS, M Bonhomme, D Lopez, A Traore, M Douris, J-S Venisse, H Cochard, E Badel, 2013 - Modulation of bud survival in Populus nigra sprouts in response to water stress-induced embolism. Tree Physiology, 33(3): 261-274. Reference Real-time PCR cycler

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Noninvasive measurement of vulnerability to drought-induced embolism by x-ray microtomography

Noninvasive measurement of vulnerability to drought-induced embolism by x-ray microtomography

CONCLUSION The results of microCT observations confirm that this technique is an excellent noninvasive method for the measurement of vulnerability to embolism, with the principal advantage that measurements can be made on intact plants. The high resolution of images allowed for the calculation of theoretical hydraulic conductivity based on xylem conduit dimensions. Therefore, we were able to estimate the impact of embolized vessels and tracheid on the hydraulic capacity of each sample. The fine spatial patterns of embolism spread within the xylem could also be followed, providing insight into the way cavitation is nucleated within the xylem. The results indicated that centrifuge techniques overestimated vulnerability to embolism in ring-porous Q. robur, consistent with previous reports suggesting that the centrifuge suffers from an open-vessel artifact when applied to long-vesseled species (Choat et al., 2010; Cochard et al., 2010; Torres-Ruiz et al., 2014). However, the centrifuge produced curves that were in excellent agreement with microCT observations for diffuse porous P. tremula 3 P. alba and the conifer P. pinaster. These results provide further evidence that the centri- fuge technique is a rapid and reliable method of assessing vulnerability to embolism in species with short vessels or tracheids but is prone to errors when a high proportion of vessels are cut open in the mea- surement sample. Caution is advised when applying this technique to species with vessel lengths that exceed the diameter of the rotor used in centrifuge methods.
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Drought-induced embolism in current-year shoots of two Mediterranean evergreen oaks

Drought-induced embolism in current-year shoots of two Mediterranean evergreen oaks

considered one of the major factors affecting plant productivity and survival ( Tyree and Sperry, 1988 ). Mediterranean-climate re- gions are characterised by recurrent droughts, with irregular/lim- ited rainfall and high evaporative demand. Climate change scenarios for the Western Mediterranean Basin foresee warmer air temperatures and an increase in the length and intensity of the seasonal summer drought ( Miranda et al., 2002 ). Trees cope with these seasonal water shortages by preventing water losses through stomatal closure and maximising the soil and groundwa- ter uptake by deep roots ( Canadell et al., 1996; David et al., 2007; Maherali et al., 2004 ). Under extreme drought, stomatal reg- ulation may not be enough to maintain leaf water potential above a critical threshold and catastrophic embolism may occur ( Sperry, 1986 ).
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Numerical simulations of coupled groundwater flow and heat transport incorporating freeze/thaw cycles and phase change in a continuous permafrost environment

Numerical simulations of coupled groundwater flow and heat transport incorporating freeze/thaw cycles and phase change in a continuous permafrost environment

iii Abstract At high northern latitudes, climate warming will induce permafrost degradation that will modify local and regional hydrogeological systems and ecosystem functionality, as well as increase the release of carbon and methane to the environment. Northern infrastructure, in particular roads and embankments, will also experience significant degradation. In this study, numerical simulations of coupled groundwater flow and heat transport have been developed to assess the effects of realistic combinations of hydrogeological parameters and surface conditions on the temporal and spatial evolution of permafrost degradation in a cold-region paved terrain, at the Iqaluit airport, Nunavut. A conceptual model is first developed for the site and a corresponding 2D numerical model is calibrated to the observed groundwater flow and thermal regime. Future climate warming impacts on the thermal regime and flow system, as well as thaw settlements are then simulated based on climate scenarios proposed by the IPCC (Intergovernmental Panel on Climate Change). Under climate warming, the surface snow cover is identified as the leading factor affecting permafrost degradation, and significantly contributes to positive feedback between the hydrogeological flow system and the frozen ground. In this case, advective heat transport plays a relatively minor, but non- negligible role compared to conductive heat transport, due to the significant extent of low- permeability soil close to surface. Conductive heat transport, which is strongly affected by the surface snow layer, controls the release of unfrozen water and the depth of the active layer as well as the magnitude of thaw settlement and frost heave.
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Recombination of vesicles during freeze-drying

Recombination of vesicles during freeze-drying

In order to understand these phenomena, it was decided to examine the state of the lipid dispersion at each stage of the manufacturing and freeze-drying process. Two methods were used. Firstly, the lipid dispersion was recovered from the freeze-drying equipment, diluted in water, and the size distribution of the vesicles was analyzed through Size Exclusion Chromatography (SEC) [14, 15]. Changes in the size distribution were taken as evidence of recombination events that occurred during freeze-drying. Secondly, the vesicle dispersion (or the freeze-dried powder) was again recovered from the freeze-drying equipment and examined without dilution through Small Angle Neutron Scattering (SANS). The interference patterns yielded the average center-center distance between vesicles, and hence the average mass of lipid per vesicle. Changes in this number indicated that recombination events had occurred. Moreover, the vesicle diameter and the separation between the surfaces of neighboring vesicles could be calculated according to a geometrical model for spherical vesicles. This made it possible to search for deviations from this model, which would indicate that the vesicles had changed shapes.
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Carbon dynamics in highly heterotrophic subarctic thaw ponds.

Carbon dynamics in highly heterotrophic subarctic thaw ponds.

tems, where bacterioplankton dominates the production of new carbon biomass in both summer and winter. 1 Introduction Traditional view of inland waters as sinks of carbon has changed during the past decades, and, at present, lakes and ponds are considered net sources of carbon to the atmosphere (Tranvik et al., 2009). Increasing attention has been given to thaw ponds and lakes after recognizing the cumulative effect of their high abundance and greenhouse gas (GHG) emis- sions on global warming (Kling et al., 1992; Walter et al., 2006; Laurion et al., 2010), especially when they emit old carbon thus having the potential to act as a positive feedback mechanism on climate (Walter Anthony et al., 2014). Thaw ponds and lakes are dominant in continuous and discontin- uous permafrost areas, for example in permafrost regions of Siberia where they represent 90 % of all lakes (Walter et al., 2006), but until recently little has been known on the limno- logical properties and microbial communities of this impor- tant freshwater ecosystem (Vonk et al., 2015).
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View of Haemodynamic consequences of pulmonary embolism

View of Haemodynamic consequences of pulmonary embolism

interactions between the pulmonary vascular anomalies, the function of the left and right ventricles and the coronary cir- culation reflect the haemodynamic changes seen at the diffe- rent stages of acute pulmonary embolism. Echocardiography allows the haemodynamic consequences of pulmonary embolism to be determined, as well as certain other scan indicators. Over the last few years, research has been focu- sed on patients at intermediate risk, i.e. not hypotensive but presenting with echocardiographic signs of right ventri- cular dysfunction, as well as an increase in myocardial markers (proBNP [brain natriuretic peptide], BNP and tro- ponin). The place for different symptomatic or etiological therapeutic treatments are discussed. To cite this journal: Réanimation 21 (2012).
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Pulmonary embolism diagnostics from the driver function

Pulmonary embolism diagnostics from the driver function

Methods: PE was induced in five pigs with cardiac measurements taken every 30 minutes. Pig-specific driver functions are estimated at each time point from aortic artery pressure waveforms. Increases over time in two validated model- based metrics indicate PE: 1) pulmonary artery resistance (Rpul); and 2) Right Ventricle Expansion Index (RVEI). Rpul and RVEI at each time point were paired to specific points on the right driver function that change as PE is induced. The significant points of interest are: 1) left-shoulder (LS) of the right driver function (correlated with the dead-space volume); 2) maximum pressure gradient (MPG) of the right driver function (related to
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Dikes on permafrost: predicting thaw and settlement

Dikes on permafrost: predicting thaw and settlement

Dikes on permafrost: predicting thaw and settlement Brown, W. G.; Johnston, G. H. https://publications-cnrc.canada.ca/fra/droits L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

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Freeze-Dried Ham Promotes Azoxymethane-Induced 
Mucin-Depleted Foci and Aberrant Crypt Foci in Rat Colon

Freeze-Dried Ham Promotes Azoxymethane-Induced Mucin-Depleted Foci and Aberrant Crypt Foci in Rat Colon

We speculated that free nitrosyl heme in processed meat is more toxic than native heme in fresh meat, which would explain why processed meat intake is more closely associated with the ri[r]

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Xylem embolism meter (Xyl'EM)

Xylem embolism meter (Xyl'EM)

Cochard H, Herbette S, Barigah T, Badel E, Ennajeh M, Vilagrosa A (2010) Does sample length influence the shape of xylem embolism vulnerability curves? A test with the Cavitron spinning technique. Plant Cell and Environment 33, 1543- 1552 Cruiziat P, Cochard H, Améglio T (2002) The hydraulic architecture of trees: main concepts and results. Annals of Forest

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Modulation of bud survival in Populus nigra sprouts in response to water stress-induced embolism

Modulation of bud survival in Populus nigra sprouts in response to water stress-induced embolism

Here, we hypothesized that bud behaviour was a key factor for tree survival during a drastic water stress. We investigated the behaviour of the buds during a drastic water stress of pop- lars for several weeks. We hypothesized that the rapid xylem embolism would break the hydraulic connections to the buds and that this process would lead to the interruption of the water and nutrient supply to the buds. These buds would rapidly become isolated, dry and die, preventing the tree from sprout- ing again. Assuming that a bud respiration decrease would be one of the first indicators predicting plant death, we investi- gated whether this loss of vitality might be related to the lack of availability of water for the bud. Thus we monitored the axillary bud metabolic activity by measuring respiration rate by micro- calorimetry. We investigated the local water distribution and sta- tus in buds and other surrounding bearer tissues using nuclear magnetic resonance (NMR) imaging. Moreover, we assessed
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Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site

Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site

from -5 to 4 °C at a thawing rate of +0.16 °C d -1 . In the unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the 14 C-hexadecane
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STUDYING WITH A FULL-FIELD MEASUREMENT TECHNIQUE THE LOCAL RESPONSE OF ASPHALT SPECIMENS SUBJECTED TO FREEZE- THAW CYCLES

STUDYING WITH A FULL-FIELD MEASUREMENT TECHNIQUE THE LOCAL RESPONSE OF ASPHALT SPECIMENS SUBJECTED TO FREEZE- THAW CYCLES

In this study, four Hot Mixtures Asphalt (HMA) specimens with 0%, 20%, 40% and 100% of RAP (Recycled Asphalt Pavement) content were considered. These materials were used in a previous study, which was devoted to the characterization of the effect of RAP on the local mechanical behavior of recycled asphalt pavements [6]. These RAP materials are composed of granite, basalt and gneiss. The virgin materials are constituted from limestone aggregates and a virgin bituminous binder. Freeze-thaw tests were carried out on these materials. They were performed in a climate chamber at

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