Improved image-based deformation measurement for geotechnical applications

This paper describes and benchmarks a new implementation of image-based deformation measurement for geotechnical applications. The updated approach combines a range of advances in image analysis algorithms and techniques best suited to geotechnical applications. Performance benchmarking of the new approach has used a series of artificial images subjected to prescribed spatially varying displacement fields. An improvement by at least a factor of 10 in measurement precision is achieved relative to the most commonly used particle image velocimetry (PIV) approach for all deformation modes, including rigid-body displacements, rotations, and strains (compressive and shear). Lastly, an example analysis of a centrifuge model test is used to demonstrate the capabilities of the new approach. The strain field generated by penetration of a flat footing and an entrapped sand plug into an underlying clay layer is computed and compared for both the current and updated algorithms. This analysis demonstrates that the enhanced measurement precision improves the clarity of the interpretation. </jats:p

Measurement of matric suction using tensiometric and axis translation techniques

Experimental equipment for the measurement of matric suction in unsaturated soils using hydraulic tensiometers and the axis translation technique share a common working principle; that is, the measurement of a pressure differential across a high air entry porous ceramic. In this paper, the current state of the art in these two suction measurement techniques is presented and discussed together with the underlying physics thereby giving the reader the necessary basis to use and interpret the results obtained from those two techniques

Human T-lymphotropic virus type 1 (HTLV-1) prevalence and quantitative detection of DNA proviral load in individuals with indeterminate/positive serological results

BACKGROUND: HTLV-1 infection is currently restricted to endemic areas. To define the prevalence of HTLV-1 infection in patients living in Italy, we first carried out a retrospective serological analysis in a group of people originating from African countries referred to our hospital from January 2003 to February 2005. We subsequently applied a real time PCR on peripheral blood mononuclear cells from subjects with positive or indeterminate serological results. METHODS: All the sera were first analysed by serological methods (ELISA and/or Western Blotting) and then the peripheral blood mononuclear cells from subjects with positive or inconclusive serological results were analyzed for the presence of proviral DNA by a sensitive SYBR Green real time PCR. In addition, twenty HTLV-I ELISA negative samples were assayed by real time PCR approach as negative controls. RESULTS: Serological results disclosed serum reactivity by ELISA (absorbance values equal or greater than the cut-off value) in 9 out of 3408 individuals attending the Sexually Transmitted Diseases Clinic and/or Oncology Department, and 2 out 534 blood donors enrolled as a control population. Irrespective of positive or inconclusive serological results, all these subjects were analyzed for the presence of proviral DNA in peripheral blood mononuclear cells by SYBR real time PCR. A clear-cut positive result for the presence of HTLV-1 DNA was obtained in two subjects from endemic areas. CONCLUSION: SYBR real time PCR cut short inconclusive serological results. This rapid and inexpensive assay showed an excellent linear dynamic range, specificity and reproducibility readily revealing and quantifying the presence of virus in PBMCs. Our results highlight the need to monitor the presence of HTLV-1 in countries which have seen a large influx of immigrants in recent years. Epidemiological surveillance and correct diagnosis are recommended to verify the prevalence and incidence of a new undesirable phenomenon