The Experts below are selected from a list of 230493 Experts worldwide ranked by ideXlab platform
Philippe Schoeneich - One of the best experts on this subject based on the ideXlab platform.
-
Evaluating the Destabilization susceptibility of active rock glaciers in the French Alps
The Cryosphere, 2019Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:Abstract. In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorphological features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A Destabilization rating was assigned by taking into account the evolution of these mapped Destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This Destabilization rating then served as input to model the occurrence of rock glacier Destabilization in relation to terrain attributes and to spatially predict the susceptibility to Destabilization at a regional scale. Significant evidence of Destabilization could be observed in 46 rock glaciers, i.e. 10 % of the total active rock glaciers in the region. Based on our susceptibility model of Destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 ∘ C isotherm (2700–2900 m a.s.l.), on north-facing slopes, steep terrain (25 to 30 ∘ ) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of Destabilization. About 3 km 2 of creeping permafrost, or 10 % of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Considering we observed that only half of these areas of creep are currently showing Destabilization evidence, we suspect there is a high potential for future rock glacier Destabilization within the French Alps.
-
Evaluating the Destabilization susceptibility of active rock glaciers in the French Alps
The Cryosphere, 2019Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorpho-logical features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A Destabilization rating was assigned by taking into account the evolution of these mapped Destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This Destabilization rating then served as input to model the occurrence of rock glacier Destabilization in relation to terrain attributes and to spatially predict the susceptibility to Destabilization at a regional scale. Significant evidence of Destabilization could be observed in 46 rock glaciers, i.e. 10% of the total active rock glaciers in the region. Based on our susceptibility model of Destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 degrees C isotherm (2700-2900ma. s.l.), on north-facing slopes, steep terrain (25 to 30 ffi) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of Destabilization. About 3 km(2) of creeping permafrost, or 10% of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Considering we observed that only half of these areas of creep are currently showing Destabilization evidence, we suspect there is a high potential for future rock glacier Destabilization within the French Alps.
-
Inferring the Destabilization susceptibility of mountain permafrostin the French Alps using an inventory of destabilized rock glaciers
2018Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:Abstract. Knowing the extent of degrading permafrost is a key issue in the context of emerging risks linked to climate change. In the present study we propose a methodology to estimate the spatial distribution of this phenomenon, focusing on the French Alps. At first, using recent orthoimages (2000 to 2013) covering the study region, we mapped the geomorphological features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps). This database was then used as support tool to rate rock glaciers Destabilization. The Destabilization rating was assigned also taking into account the surface deformation patterns of the rock glacier, observable by comparing the orthoimages. The Destabilization rating served as database to model the occurrence of Destabilization in relation to terrain attributes and to predict the susceptibility to Destabilization at the regional scale. Potential Destabilization could be observed in 58 rock glaciers, i.e. 12 of the total active rock glaciers in the region. Potentially destabilized rock glaciers were found to be more prone to strong acceleration than stable rock glaciers within the period 2000–2013. Modelling the occurrence of Destabilization suggested that this phenomenon is more likely to occur in elevations around the 0 °C isotherm (2700–2900 m.s.l.), on north-exposed, steep (up to 30°) and flat to slightly convex topographies. Model performances were good (AUROC: 0.76) and the susceptibility map reproduced well the observable patterns. About 3 km 2 of creeping permafrost, i.e. 10 % of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Only half of this surface is currently showing Destabilization evidence, suggesting that a significant amount of rock glaciers are candidates for future Destabilization.
Marco Marcer - One of the best experts on this subject based on the ideXlab platform.
-
Evaluating the Destabilization susceptibility of active rock glaciers in the French Alps
The Cryosphere, 2019Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:Abstract. In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorphological features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A Destabilization rating was assigned by taking into account the evolution of these mapped Destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This Destabilization rating then served as input to model the occurrence of rock glacier Destabilization in relation to terrain attributes and to spatially predict the susceptibility to Destabilization at a regional scale. Significant evidence of Destabilization could be observed in 46 rock glaciers, i.e. 10 % of the total active rock glaciers in the region. Based on our susceptibility model of Destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 ∘ C isotherm (2700–2900 m a.s.l.), on north-facing slopes, steep terrain (25 to 30 ∘ ) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of Destabilization. About 3 km 2 of creeping permafrost, or 10 % of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Considering we observed that only half of these areas of creep are currently showing Destabilization evidence, we suspect there is a high potential for future rock glacier Destabilization within the French Alps.
-
Evaluating the Destabilization susceptibility of active rock glaciers in the French Alps
The Cryosphere, 2019Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorpho-logical features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A Destabilization rating was assigned by taking into account the evolution of these mapped Destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This Destabilization rating then served as input to model the occurrence of rock glacier Destabilization in relation to terrain attributes and to spatially predict the susceptibility to Destabilization at a regional scale. Significant evidence of Destabilization could be observed in 46 rock glaciers, i.e. 10% of the total active rock glaciers in the region. Based on our susceptibility model of Destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 degrees C isotherm (2700-2900ma. s.l.), on north-facing slopes, steep terrain (25 to 30 ffi) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of Destabilization. About 3 km(2) of creeping permafrost, or 10% of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Considering we observed that only half of these areas of creep are currently showing Destabilization evidence, we suspect there is a high potential for future rock glacier Destabilization within the French Alps.
-
Rock glacier Destabilization in the French Alps : insights from regional and local scale assessments
2018Co-Authors: Marco MarcerAbstract:As occurring to several geosystems on our planet, mountain permafrost is threatened by climate change as prolonged warming may compromise the geotechnical properties of the frozen ground. As result, increasing occurrence of rockfall activity, thermokarst formation and rock glacier acceleration was observed in the past decades. Rock glacier Destabilization, a process that compromises the structural integrity of these landforms, seems to be linked to atmospheric warming, gaining interest in the past years. The Destabilization, which may be triggered by warming permafrost or mechanical stress, is characterized by an anomalous acceleration of the landform and the occurrence of specific features such as cracks and crevasses on its surface. Although the occurrence of these processes is mostly transitory, determining a textit{crisis} phase of the landform, in exceptional cases it may lead the rock glacier to structural collapse.This PhD thesis provided an assessment on the occurrence and related processes of rock glacier Destabilization in the French Alps. At first, the spatial occurrence of debris permafrost was assessed in order to provide the permafrost distribution map of the French Alps, a tool that was necessary to evaluate permafrost conditions at rock glaciers sites. The second step consisted in an identification of destabilized rock glaciers in the region, which was done by multiple orthoimages interpretation aimed to identify features typically observable on destabilized rock glacier. Once identified the destabilized rock glaciers it was possible to analyse the typical topographical settings in which Destabilization occurs and to to spot those landforms that are susceptible to experience this phenomenon. After these efforts at the regional scale, the focus was shifted towards local scale investigations at the Lou rock glacier, a partially destabilized landform that, due to frontal failure, in August 2015 triggered a debris flow that caused significant damages to buildings. The analysis aimed to better define the circumstances of this event, focusing on preconditioning, preparatory and triggering factors and their interaction with the Destabilization process.The results provided interesting insights on the issue of destabilizing rock glaciers in the region. Permafrost distribution modeling demonstrated the large extents of the periglacial zone in the region as it can be found in debris slopes above 2300 - 2900 m.a.s.l. depending upon solar exposure and regional precipitation characteristics. Rock glacier Destabilization was observed on 46 landforms, i.e. the 12% of the active rock glaciers. Destabilization was found to be more likely to occur in specific local topo-climatic conditions, consisting of north facing, steep and convex slopes at the lower margins of the permafrost zone. A large number of rock glaciers currently not showing Destabilization was found to be located in these conditions and suggested to be susceptible to future Destabilization. As demonstrated by the Lou rock glacier analysis, Destabilization was found to be a relevant phenomena in the context of permafrost hazards. At this site, rock glacier Destabilization was linked to a rapid frontal advance towards a torrential gully. This process seemed to have increased the site predisposition to frontal failure as a mild rainstorm was sufficient to trigger the event.Despite methodological uncertainties, results indicated that Destabilization occurrence is widespread and it may rise the hazard level of a site connected to human infrastructures. Therefore, it is suggested that, where it has been modelled and where stakes may be at risk downslope, rock glacier Destabilization deserves to be more carefully investigated. In this sense further efforts should focus towards a better understanding of the Destabilization process by site monitoring as well as towards a comprehensive hazard assessment linked to this phenomenon.
-
Inferring the Destabilization susceptibility of mountain permafrostin the French Alps using an inventory of destabilized rock glaciers
2018Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:Abstract. Knowing the extent of degrading permafrost is a key issue in the context of emerging risks linked to climate change. In the present study we propose a methodology to estimate the spatial distribution of this phenomenon, focusing on the French Alps. At first, using recent orthoimages (2000 to 2013) covering the study region, we mapped the geomorphological features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps). This database was then used as support tool to rate rock glaciers Destabilization. The Destabilization rating was assigned also taking into account the surface deformation patterns of the rock glacier, observable by comparing the orthoimages. The Destabilization rating served as database to model the occurrence of Destabilization in relation to terrain attributes and to predict the susceptibility to Destabilization at the regional scale. Potential Destabilization could be observed in 58 rock glaciers, i.e. 12 of the total active rock glaciers in the region. Potentially destabilized rock glaciers were found to be more prone to strong acceleration than stable rock glaciers within the period 2000–2013. Modelling the occurrence of Destabilization suggested that this phenomenon is more likely to occur in elevations around the 0 °C isotherm (2700–2900 m.s.l.), on north-exposed, steep (up to 30°) and flat to slightly convex topographies. Model performances were good (AUROC: 0.76) and the susceptibility map reproduced well the observable patterns. About 3 km 2 of creeping permafrost, i.e. 10 % of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Only half of this surface is currently showing Destabilization evidence, suggesting that a significant amount of rock glaciers are candidates for future Destabilization.
Frederic Gaucheron - One of the best experts on this subject based on the ideXlab platform.
-
Ser2 from Serratia liquefaciens L53: A new heat stable protease able to destabilize UHT milk during its storage
Food Chemistry, 2017Co-Authors: François Baglinière, Gaëlle Tanguy, Rafael Locatelli Salgado, Marielle Harel-oger, Benoît Robert, Julien Jardin, Maria Cristina Dantas Vanetti, Florence Rousseau, Frederic GaucheronAbstract:Abstract The heat-stable protease Ser2 is secreted by the species Serratia liquefaciens, a psychrotrophic bacteria frequently found in raw milk. To understand the physicochemical modifications of casein micelles induced by Ser2 and to confirm its implication in UHT milk Destabilization, the enzyme was purified and added to microfiltered raw milk before UHT treatment. UHT milk Destabilization was investigated during 90 days of storage. A visual Destabilization appeared after 8 days of storage with the presence of sediment. Zeta potential increase and formation of aggregates were observed during the storage. Using tandem mass spectrometry, numerous released peptides from the four caseins were identified at the end of storage. Caseins were hydrolyzed in the preferential order β- > αs1- > κ- > αs2. No specific peptidic hydrolysed bond was detected. The present study confirmed that the presence of the protease Ser2 in raw milk can be one of the main causes of UHT milk Destabilization.
-
Proteolytic Destabilization of casein micelle in UHT-milk during storage: impact of different strains of Pseudomonas fluorescens
2011Co-Authors: François Baglinière, Benoît Robert, Florence Rousseau, Gaelle Tanguy-sai, Frederic GaucheronAbstract:UHT sterilization combined with an aseptic packaging provides drinking milk that is microbiologically safe and can be stored at ambient temperature for several months. In some cases, commercial UHT milk can be destabilized by formation of a gel or sediment. Different studies have shown that residual activities of heat-resistant proteases of Pseudomonas fluorescens modify physico-chemical properties of casein micelles and lead to Destabilization of UHT-milk. In our previous study, Destabilization happened due to one strain of Pseudomonas fluorescens. In this present work, a wider range of strains were tested to explore further their impact on the quality of UHT-milk and to highlight the phenomena that cause proteolysis of casein micelles. Nine strains of Pseudomonas fluorescens secreting the heat-resistant protease aprX were selected as a function of their proteolytic potential. Each strain was inoculated in microfiltered milk, heat-treated at 140°C for 4 seconds and stored 90 days at 20°C. The physico-chemical characteristics of casein micelles were appreciated by evaluating their aggregation and measuring their size, zeta potential and hydration. In parallel, global proteolysis was determined by evaluating non casein nitrogen (NCN) and non protein nitrogen (NPN) contents. After 90 days of storage, Destabilization of UHT-milks contaminated with the strains of Pseudomonas fluorescens was visual with presence of aggregates. Moreover, physico-chemical characteristics of casein micelles showed roughly the same evolution. Zeta potential, size, NCN and NPN contents increased whereas hydration decreased. The higher proteolytic activity was, the faster Destabilization of milk happened. These results confirm that Destabilization of UHT-milk occurs due to proteolysis of casein micelles. It suggests also that the heat-resistant protease aprX causes this proteolysis. To check this assumption, an experiment with inoculation of the purified enzyme in microfiltered milk is planned. Identification of cleavage sites is also a future project.
B Hernandez - One of the best experts on this subject based on the ideXlab platform.
-
kinetics of secondary carbides precipitation in a high chromium white iron
Journal of Materials Engineering and Performance, 2003Co-Authors: A Bedollajacuinde, L Arias, B HernandezAbstract:This work analyzes the rate of secondary carbides precipitation during the Destabilization heat treatment of a 17% Cr white iron. The experimental iron was characterized in the as-cast conditions to have comparable parameters with the heat treated samples. Destabilization heat treatments were undertaken at temperatures of 900, 1000, and 1150 °C for between 5 min and 8 h; each sample was water quenched immediately after being taken out of the furnace. Characterization was carried out by optical and electron microscopy, image analysis, and energy dispersive spectroscopy (EDS) microanalysis; hardness and microhardness were also evaluated. It was found that most of the secondary carbides that precipitate (between 2–30% of the matrix volume) precipitated in less than 2 h for the lowest Destabilization temperature (900 °C). The secondary carbides volume fraction was found to increase for lower Destabilization temperatures and large soaking times. A very low carbide precipitation along with a stabilization of the austenite phase occurred for heat treatments at 1150 °C. The results are discussed in terms of the solubility of chromium and carbon in the austenite phase at the different treatment temperatures.
Alexander Brenning - One of the best experts on this subject based on the ideXlab platform.
-
Evaluating the Destabilization susceptibility of active rock glaciers in the French Alps
The Cryosphere, 2019Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:Abstract. In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorphological features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A Destabilization rating was assigned by taking into account the evolution of these mapped Destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This Destabilization rating then served as input to model the occurrence of rock glacier Destabilization in relation to terrain attributes and to spatially predict the susceptibility to Destabilization at a regional scale. Significant evidence of Destabilization could be observed in 46 rock glaciers, i.e. 10 % of the total active rock glaciers in the region. Based on our susceptibility model of Destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 ∘ C isotherm (2700–2900 m a.s.l.), on north-facing slopes, steep terrain (25 to 30 ∘ ) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of Destabilization. About 3 km 2 of creeping permafrost, or 10 % of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Considering we observed that only half of these areas of creep are currently showing Destabilization evidence, we suspect there is a high potential for future rock glacier Destabilization within the French Alps.
-
Evaluating the Destabilization susceptibility of active rock glaciers in the French Alps
The Cryosphere, 2019Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:In this study, we propose a methodology to estimate the spatial distribution of destabilizing rock glaciers, with a focus on the French Alps. We mapped geomorpho-logical features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps) using orthoimages taken from 2000 to 2013. A Destabilization rating was assigned by taking into account the evolution of these mapped Destabilization geomorphological features and by observing the surface deformation patterns of the rock glacier, also using the available orthoimages. This Destabilization rating then served as input to model the occurrence of rock glacier Destabilization in relation to terrain attributes and to spatially predict the susceptibility to Destabilization at a regional scale. Significant evidence of Destabilization could be observed in 46 rock glaciers, i.e. 10% of the total active rock glaciers in the region. Based on our susceptibility model of Destabilization occurrence, it was found that this phenomenon is more likely to occur in elevations around the 0 degrees C isotherm (2700-2900ma. s.l.), on north-facing slopes, steep terrain (25 to 30 ffi) and flat to slightly convex topographies. Model performance was good (AUROC = 0.76), and the susceptibility map also performed well at reproducing observable patterns of Destabilization. About 3 km(2) of creeping permafrost, or 10% of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Considering we observed that only half of these areas of creep are currently showing Destabilization evidence, we suspect there is a high potential for future rock glacier Destabilization within the French Alps.
-
Inferring the Destabilization susceptibility of mountain permafrostin the French Alps using an inventory of destabilized rock glaciers
2018Co-Authors: Marco Marcer, Charlie Serrano, Alexander Brenning, Xavier Bodin, Jason Goetz, Philippe SchoeneichAbstract:Abstract. Knowing the extent of degrading permafrost is a key issue in the context of emerging risks linked to climate change. In the present study we propose a methodology to estimate the spatial distribution of this phenomenon, focusing on the French Alps. At first, using recent orthoimages (2000 to 2013) covering the study region, we mapped the geomorphological features that can be typically found in cases of rock glacier Destabilization (e.g. crevasses and scarps). This database was then used as support tool to rate rock glaciers Destabilization. The Destabilization rating was assigned also taking into account the surface deformation patterns of the rock glacier, observable by comparing the orthoimages. The Destabilization rating served as database to model the occurrence of Destabilization in relation to terrain attributes and to predict the susceptibility to Destabilization at the regional scale. Potential Destabilization could be observed in 58 rock glaciers, i.e. 12 of the total active rock glaciers in the region. Potentially destabilized rock glaciers were found to be more prone to strong acceleration than stable rock glaciers within the period 2000–2013. Modelling the occurrence of Destabilization suggested that this phenomenon is more likely to occur in elevations around the 0 °C isotherm (2700–2900 m.s.l.), on north-exposed, steep (up to 30°) and flat to slightly convex topographies. Model performances were good (AUROC: 0.76) and the susceptibility map reproduced well the observable patterns. About 3 km 2 of creeping permafrost, i.e. 10 % of the surface occupied by active rock glaciers, had a high susceptibility to Destabilization. Only half of this surface is currently showing Destabilization evidence, suggesting that a significant amount of rock glaciers are candidates for future Destabilization.
