Remote thermal detection of exfoliation sheet deformation.

A growing body of research indicates that rock slope failures, particularly from exfoliating cliffs, are promoted by rock deformations induced by daily temperature cycles. Although previous research has described how these deformations occur, full three-dimensional monitoring of both the deformations and the associated temperature changes has not yet been performed. Here we use integrated terrestrial laser scanning (TLS) and infrared thermography (IRT) techniques to monitor daily deformations of two granitic exfoliating cliffs in Yosemite National Park (CA, USA).

The three-stage rock failure dynamics of the Drus (Mont Blanc massif, France) since the June 2005 large event.

Since the end of the Little Ice Age, the west face of the Drus (Mont Blanc massif, France) has been affected by a retrogressive erosion dynamic marked by large rockfall events. From the 1950s onwards, the rock failure frequency gradually increased until the large rockfall event (292,680 m) of June 2005, which made the Bonatti Pillar disappear. Aiming to characterize the rock failure activity following this major event, which may be related to permafrost warming, the granitic rock face was scanned each autumn between October 2005 and September 2016 using medium- and long-range terrestrial laser scanners.

Toward community predictions: Multi-scale modelling of mountain breeding birds' habitat suitability, landscape preferences, and environmental drivers.

Across a large mountain area of the western Swiss Alps, we used occurrence data (presence-only points) of bird species to find suitable modelling solutions and build reliable distribution maps to deal with biodiversity and conservation necessities of bird species at finer scales. We have performed a multi-scale method of modelling, which uses distance, climatic, and focal variables at different scales (neighboring window sizes), to estimate the efficient scale of each environmental predictor and enhance our knowledge on how birds interact with their complex environment. To identify the best radius for each focal variable and the most efficient impact scale of each predictor, we have fitted univariate models per species.

Detection of rock bridges by infrared thermal imaging and modeling.

Characterization of rock discontinuities and rock bridges is required to define stability conditions of fractured rock masses in both natural and engineered environments. Although remote sensing methods for mapping discontinuities have improved in recent years, remote detection of intact rock bridges on cliff faces remains challenging, with their existence typically confirmed only after failure. In steep exfoliating cliffs, such as El Capitan in Yosemite Valley (California, USA), rockfalls mainly occur along cliff-parallel exfoliation joints, with rock bridges playing a key role in the stability of partially detached exfoliation sheets.

Cratering response during droplet impacts on granular beds.

This experimental work focuses on the cratering response of granular layers induced by liquid droplet impacts. A droplet impact results in severe granular layer deformation, crater formation and deposits in the vicinity of the impact center. High-precision three-dimensional imaging of the granular layer surface revealed important characteristics of liquid impacts on granular matter, such as singular asymmetric deformations of the layer.

Low number of fixed somatic mutations in a long-lived oak tree.

Because plants do not possess a defined germline, deleterious somatic mutations can be passed to gametes, and a large number of cell divisions separating zygote from gamete formation may lead to many mutations in long-lived plants. We sequenced the genome of two terminal branches of a 234-year-old oak tree and found several fixed somatic single-nucleotide variants whose sequential appearance in the tree could be traced along nested sectors of younger branches. Our data suggest that stem cells of shoot meristems in trees are robustly protected from the accumulation of mutations.

Improved predictive mapping of indoor radon concentrations using ensemble regression trees based on automatic clustering of geological units.

Purpose: According to estimations around 230 people die as a result of radon exposure in Switzerland. This public health concern makes reliable indoor radon prediction and mapping methods necessary in order to improve risk communication to the public. The aim of this study was to develop an automated method to classify lithological units according to their radon characteristics and to develop mapping and predictive tools in order to improve local radon prediction.

Predictive analysis and mapping of indoor radon concentrations in a complex environment using kernel estimation: an application to Switzerland.

Purpose: The aim of this study was to develop models based on kernel regression and probability estimation in order to predict and map IRC in Switzerland by taking into account all of the following: architectural factors, spatial relationships between the measurements, as well as geological information.

Methods: We looked at about 240,000 IRC measurements carried out in about 150,000 houses. As predictor variables we included: building type, foundation type, year of construction, detector type, geographical coordinates, altitude, temperature and lithology into the kernel estimation models.

Major influencing factors of indoor radon concentrations in Switzerland.

Purpose: In Switzerland, nationwide large-scale radon surveys have been conducted since the early 1980s to establish the distribution of indoor radon concentrations (IRC). The aim of this work was to study the factors influencing IRC in Switzerland using univariate analyses that take into account biases caused by spatial irregularities of sampling.

Methods: About 212,000 IRC measurements carried out in more than 136,000 dwellings were available for this study.