286 research outputs found
Instrumentation of Flexible Buried Culvert Subjected to Rockfall Loading
Natural hazards, like avalanches and rock falls, will always be a major concern for infrastructure, i.e. roads and railways, in mountain areas. Several measures are available to protect this infrastructure, but especially in areas with steep slopes, rockfall- or avalanche galleries are commonly used. These structures, which are made to withstand high impact forces, can be made of reinforced/pre-stressed concrete culverts covered with soil. A possibly cheaper and equally safe alternative could be to use a buried corrugated steel culvert.
To investigate the use of buried corrugated steel culverts as rock fall protection structures an experimental study has been carried out. A 4.0 m span half arch corrugated steel culvert was buried in soil and instrumented during rockfall loading. Rock blocks with various weights have been dropped from different heights on a corrugated steel culvert covered with a cushion material. Tests were conducted with dense backfill in near zone and regular backfill in the cushion layer zone.
Measurements were made during both construction phase and during rockfall phase. During construction phase measurements were made to monitor culvert shape and culvert strains. During impact loading from rock blocks decelerations and transmitted accelerations were monitored together with change of culvert shape and deformations. Deceleration of the rock blocks was also documented with a high speed camera.
The goal of this study were to obtain knowledge which can be used in design codes in the future for flexible rockfall- and avalanche shelters
Managing Access to Biobanks:How Can We Reconcile Privacy and Public Interests in Genetic Research?
This article is concerned with the ultimate objectives of genetic biobanks set up to promote the public interestâbeing the sharing of samples and data for medical researchâand the consequences for personal privacy of realising them. Our aim is to chart the values, interests and principles in play, to consider the challenges of realizing biobanking objectives on a global scale, and to propose viable ways forward that ensure, as far as possible, that access provisions remain fit for purpose throughout the entire life of a biobank, while adequately protecting the privacy interests at stake. It is argued that key features in any robust access model must include mechanisms to (a) maintain participant trust in management of the resource and to measure and respond to participantsâ expectations, (b) facilitate and promote the sharing of benefits, and (c) respond timeously and effectively to new challenges
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Microstructural study of the deformation zones during cone penetration in silt at variable penetration rates
During conventional cone penetration testing in silt, the soil will normally be partially drained. If the penetration rate varies, time for drainage is altered and therefore the measured cone resistance and pore pressure will change. This paper studies the change in soil microstructure around the probe during cone penetration carried out at different penetration rates to investigate the failure mechanism and the processes controlling drainage in silt. Backscattered electron images of polished thin sections prepared from frozen samples at the end of penetration were used. Making use of advanced image processing techniques, the statistical distribution of particle orientations and the local porosity were investigated for the zones around the cone tip and the shaft. The spatial distribution of the measured microscale parameters in the region near the probe indicates that the soil deformation during CPTU in silt leads to the formation of both contractive and dilative zones. The macro response of the material, presented by the pore pressure and the cone penetration resistance measured during the test, results from the competition between these zones during penetration, which is shown to be dependent on the penetration rate
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Microstructural study of the deformation zones around a penetrating coned tip in silty soil
The change in soil microstructure around the penetrating probe during a cone penetration test is investigated. Backscattered electron images of polished thin sections prepared from frozen samples at the end of penetration are used. The images have a spatial resolution of 0.4 ”m/pixel that allow a clear identification of grains and pore spaces. The statistical distribution of the change of particles orientation is analyzed for the zones around the cone tip and the shaft. Quantitative analysis of the change in porosity near the penetrating object is investigated. An increase in porosity and a decrease in the anisotropy of particle orientations from the cone and further out confirm that the soil deformation during CPTU in silt is a combination of compaction and dilative behavior that might influence the pore pressure distribution during penetration
Research in and application of modern automatic control theory to nuclear rocket dynamics and control, volume I Semiannual status report
Linear optimal feedback control theory for nuclear rocket dynamics and control problem
A Bayesian approach to linking archaeological, paleoenvironmental and documentary datasets relating to the settlement of Iceland (LandnĂĄm)
YesIcelandic settlement (LandnĂĄm) period farmsteads offer opportunities to explore the nature and timing of anthropogenic activities and environmental impacts of the first Holocene farming communities. We employ Bayesian statistical modelling of archaeological, paleoenvironmental and documentary datasets to present a framework for improving chronological robustness of archaeological events. Specifically, we discuss events relevant to the farm HrĂsbrĂș, an initial and complex settlement site in southwest Iceland. We demonstrate that tephra layers are key in constraining reliable chronologies, especially when combined with related datasets and treated in a Bayesian framework. The work presented here confirms earlier interpretations of the chronology of the site while providing increased confidence in the robustness of the chronology. Most importantly, integrated modelling of AMS radiocarbon dates on Hordeum vulgare grains, palynological data, documented evidence from textual records and typologically diagnostic artefacts yield increased dating reliability. The analysis has also shown that AMS radiocarbon dates on bone collagen need further scrutiny. Specifically for the HrĂsbrĂș farm, first anthropogenic footprint palynomorph taxa are estimated to around AD 830â881 (at 95.4% confidence level), most likely before the tephra fall out of AD 877 ± 1 (the LandnĂĄm tephra layer), demonstrating the use of arable fields before the first known structures were built at HrĂsbrĂș (AD 874â951) and prior to the conventionally accepted date of the settlement of Iceland. Finally, we highlight the importance of considering multidisciplinary factors for other archaeological and paleoecological studies of early farming communities of previously uninhabited island areas
Real-world comparison of the effects of etanercept and adalimumab on well-being in non-systemic juvenile idiopathic arthritis: a propensity score matched cohort study
Background: Etanercept (ETN) and adalimumab (ADA) are considered equally efective biologicals in the treatâ
ment of arthritis in juvenile idiopathic arthritis (JIA) but no studies have compared their impact on patient-reported
well-being. The objective of this study was to determine whether ETN and ADA have a diferential efect on patientreported well-being in non-systemic JIA using real-world data.
Methods: Biological-naive patients without a history of uveitis were selected from the international Pharmachild
registry. Patients starting ETN were matched to patients starting ADA based on propensity score and outcomes were
collected at time of therapy initiation and 3â12 months afterwards. Primary outcome at follow-up was the improveâ
ment in Juvenile Arthritis Multidimensional Assessment Report (JAMAR) visual analogue scale (VAS) well-being score
from baseline. Secondary outcomes at follow-up were decrease in active joint count, adverse events and uveitis
events. Outcomes were analyzed using linear and logistic mixed efects models.
Results: Out of 158 eligible patients, 45 ETN starters and 45 ADA starters could be propensity score matched resultâ
ing in similar VAS well-being scores at baseline. At follow-up, the median improvement in VAS well-being was 2 (interâ
quartile range (IQR): 0.0 â 4.0) and scores were signifcantly better (P=0.01) for ETN starters (median 0.0, IQR: 0.0 â 1.0)
compared to ADA starters (median 1.0, IQR: 0.0 â 3.5). The estimated mean diference in VAS well-being improvement
from baseline for ETN versus ADA was 0.89 (95% CI: -0.01 â 1.78; P=0.06). The estimated mean diference in active
joint count decrease was -0.36 (95% CI: -1.02 â 0.30; P=0.28) and odds ratio for adverse events was 0.48 (95% CI: 0.16
â1.44; P=0.19). One uveitis event was observed in the ETN group.
Conclusions: Both ETN and ADA improve well-being in non-systemic JIA. Our data might indicate a trend towards a
slightly stronger efect for ETN, but larger studies are needed to confrm this given the lack of statistical signifcance
A survey of national and multi-national registries and cohort studies in juvenile idiopathic arthritis: Challenges and opportunities
Background: To characterize the existing national and multi-national registries and cohort studies in juvenile idiopathic arthritis (JIA) and identify differences as well as areas of potential future collaboration. Methods: We surveyed investigators from North America, Europe, and Australia about existing JIA cohort studies and registries. We excluded cross-sectional studies. We captured information about study design, duration, location, inclusion criteria, data elements and collection methods. Results: We received survey results from 18 studies, including 11 national and 7 multi-national studies representing 37 countries in total. Study designs included inception cohorts, prevalent disease cohorts, and new treatment cohorts (several of which contribute to pharmacosurveillance activities). Despite numerous differences, the data elements collected across the studies was quite similar, with most studies collecting at least 5 of the 6 American College of Rheumatology core set variables and the data needed to calculate the 3-variable clinical juvenile disease activity score. Most studies were collecting medication initiation and discontinuation dates and were attempting to capture serious adverse events. Conclusion: There is a wide-range of large, ongoing JIA registries and cohort studies around the world. Our survey results indicate significant potential for future collaborative work using data from different studies and both combined and comparative analyses
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