Suchergebnisse

Abstract. Heavy rains spread over some interval preceding large landslides in sensitive glaciomarine clay in eastern Canada are often noted as a triggering or causative factor in case studies or research reports for individual landslides, although the quantity or duration of the triggering rain event has never been characterized adequately. We selected five large landslide events that occurred in the glaciomarine clay in eastern Canada, and calculated cumulative antecedent precipitation for intervals ranging between one and 365 days preceding each event. We also calculated the antecedent precipitation values for every other day in the record, and computed the relative rank of the landslide day within the complete record. Our results show that several intervals for each landslide event are highly ranked – including those preceding a presumably earthquake-triggered landslide – but overall the rankings were highly variable, ranging between 99% and 6%. The set of highest-ranking intervals are unique for each event, including both short and long-term cumulative precipitation. All of the landslides occurred in the spring months, and the release of sequestered surface and ground water during the spring ground thaw may be related to the timing of the large landslides, so that the evolution of ground frost in the early winter may be of interest for landslide prediction. We found no simple precipitation threshold for triggering large landslides in sensitive glaciomarine clay in eastern Canada, suggesting that some complex temporal and spatial combination of pre-conditions, external energy (e.g. earthquakes), precipitation triggers and other factors such as ground frost formation and thaw are required to trigger a landslide.

Abstract. Rockfall presents an ongoing challenge to the safe
operation of transportation infrastructure, creating hazardous conditions
which can result in damage to roads and railways, as well as loss of life.
Rockfall risk assessment frameworks often involve the determination of
rockfall runout in an attempt to understand the likelihood that rockfall
debris will reach an element at risk. Rockfall modelling programs which
simulate the trajectory of rockfall material are one method commonly used to
assess potential runout. This study aims to demonstrate the effectiveness of
a rockfall simulation prototype which uses the Unity 3D game engine. The
technique is capable of simulating rockfall events comprised of many mobile
fragments, a limitation of many industry standard rockfall modelling
programs. Five fragmental rockfalls were simulated using the technique, with
slope and rockfall geometries constructed from high-resolution terrestrial
laser scans. Simulated change detection was produced for each of the events
and compared to the actual change detection results for each rockfall as a
basis for testing model performance. In each case the simulated change
detection results aligned well with the actual observed change in terms of
location and magnitude. An example of how the technique could be used to
support the design of rockfall catchment ditches is shown. Suggestions are
made for future development of the simulation technique with a focus on
better informing simulated rockfall fragment size and the timing of
fragmentation.

Abstract. Rockfall is a complex natural process that can present risks to
the effective operation of infrastructure in mountainous terrain. Remote
sensing tools and techniques are rapidly becoming the state of the practice in
the characterization, monitoring and management of these geohazards. The aim
of this study is to address the methods and implications of how the
dimensions of three-dimensional rockfall objects, derived from sequential
terrestrial laser scans (TLSs), are measured. Previous approaches are
reviewed, and two new methods are introduced in an attempt to standardize
the process. The approaches are applied to a set of synthetic rockfall
objects generated in the open-source software package Blender. Fifty
rockfall events derived from sequential TLS monitoring in the White Canyon,
British Columbia, Canada, are used to demonstrate the application of the
proposed algorithms. This study illustrates that the method used to
calculate the rockfall dimensions has a significant impact on how the shape
of a rockfall object is classified. This has implications for rockfall
modelling as the block shape is known to influence rockfall runout.

Abstract. Remote sensing techniques can be used to gain a more detailed understanding
of hazardous rock slopes along railway corridors that would otherwise be
inaccessible. Multiple datasets can be used to identify changes over time,
creating an inventory of events to produce magnitude–frequency relationships
for rockfalls sourced on the slope. This study presents a method for using
the remotely sensed data to develop inputs to rockfall simulations, including
rockfall source locations and slope material parameters, which can be used to
determine the likelihood of a rockfall impacting the railway tracks given its
source zone location and volume. The results of the simulations can be
related to the rockfall inventory to develop modified magnitude–frequency
curves presenting a more realistic estimate of the hazard. These methods were
developed using the RockyFor3D software and lidar and photogrammetry data
collected over several years at White Canyon, British Columbia, Canada,
where the Canadian National (CN) Rail main line runs along the base of the slope. Rockfalls
sourced closer to the tracks were more likely to be deposited on the track or
in the ditch, and of these, rockfalls between 0.1 and 10 m3 were
the most likely to be deposited. Smaller blocks did not travel far enough to
reach the bottom of the slope and larger blocks were deposited past the
tracks. Applying the results of the simulations to a database of over 2000
rockfall events, a modified magnitude–frequency can be created, allowing the
frequency of rockfalls deposited on the railway tracks or in ditches to be
determined. Suggestions are made for future development of the methods
including refinement of input parameters and extension to other modelling
packages.

Article ; Copyright © 2015 The Authors. Arthritis & Rheumatology is published by Wiley Periodicals, Inc. on behalf of the American College of Rheumatology. ; Objective: Bronchiectasis (BR) is a risk factor for rheumatoid arthritis (RA). Here we examine the potential of BR in generating rheumatoid factors (RFs) and anti-citrullinated peptide antibodies (ACPA) in patients with BR alone and in patients with BR and RA (BRRA). Methods: We studied 122 patients with BR alone, 50 BRRA, 50 RA without lung disease, with 87 asthma and 79 healthy subjects as controls. RFs were measured by an automated analyzer, and ACPA using CCP2. Fine specificities to citrullinated α-enolase (CEP-1), citrullinated vimentin (cVim) and fibrinogen (cFib) with their arginine control peptides (REP-1, Vim and Fib) measured by ELISA. Results: In the BR patients 39% were ever smokers compared to 42% of the controls. Serum samples from BR patients had an increased frequency of RF (25%; p< 0.05) and 5% to CCP2, 7% to CEP-1, 7% to cVIM (all p=ns) and 12% cFib (p <0.05). There was also a corresponding increase in antibodies to the arginine-containing control peptides in the BR patients; REP-1, 19% (p< 0.01) and Vim, 16% (p<0.05), demonstrating that the ACPA response in BR is not citrulline-specific. Lack of citrulline specificity was further confirmed by absorption studies. In BRRA all ACPA specificities were highly citrulline-specific. Conclusion: Bronchiectasis is an unusual but potent model for the induction of autoimmunity in RA by bacterial infection in the lung. Our study suggests that in the early stages of tolerance breakdown, the ACPA response is not citrulline-specific, but becomes more so in those patients with BR that develop BRRA. ; Arthritis Research UK ; European Union ; IMI project BTCure ; 7th Framework Programme project Gums and Joints