Methodology for Validating Artifact Removal Techniques for Physiological Signals

Artifact removal from physiological signals is an essential component of the biosignal processing pipeline. The need for powerful and robust methods for this process has become particularly acute as healthcare technology deployment undergoes transition from the current hospital-centric setting toward a wearable and ubiquitous monitoring environment. Currently, determining the relative efficacy and performance of the multiple artifact removal techniques available on real world data can be problematic, due to incomplete information on the uncorrupted desired signal. The majority of techniques are presently evaluated using simulated data, and therefore, the quality of the conclusions is contingent on the fidelity of the model used. Consequently, in the biomedical signal processing community, there is considerable focus on the generation and validation of appropriate signal models for use in artifact suppression. Most approaches rely on mathematical models which capture suitable approximations to the signal dynamics or underlying physiology and, therefore, introduce some uncertainty to subsequent predictions of algorithm performance. This paper describes a more empirical approach to the modeling of the desired signal that we demonstrate for functional brain monitoring tasks which allows for the procurement of a ground truth signal which is highly correlated to a true desired signal that has been contaminated with artifacts. The availability of this ground truth, together with the corrupted signal, can then aid in determining the efficacy of selected artifact removal techniques. A number of commonly implemented artifact removal techniques were evaluated using the described methodology to validate the proposed novel test platform. © 2012 IEEE.

Gazing at Ground Zero: Tourism, Voyeurism and Spectacle

This essay uses the temporary viewing platform at the site of the former World Trade Center to explore our fascination with violence, conflict and disaster. It illustrates how discourses of voyeurism and authenticity promote a desire for sites of horror, and examines how that desire both disrupts and reinforces our prevailing interpretations of global politics. The viewing platform at Ground Zero was initially constructed to manage the thousands of people who traveled to New York in response to the shocking media images of 11 September. However, their desire to escape mediation and touch "the real" had the opposite effect - it transformed Ground Zero into a tourist attraction. Using Ground Zero as a starting point, this essay theorizes discourses of voyeurism and authenticity through the work of Baudrillard, Debord and Bauman in an effort to position the tourist as a significant political subject.

Searching for the IRA 'disappeared': Ground-penetrating radar investigation of a churchyard burial site, Northern Ireland

A search for the body of a victim of terrorist abduction and murder was made in a graveyard on the periphery of a major conurbation in Northern Ireland. The area is politically sensitive and the case of high profile. This required non-invasive, completely non-destructive and rapid assessment of the scene. A MALA RAMAC ground-penetrating radar system was used to achieve these objectives. Unprocessed and processed 400MHz data shows the presence of a collapse feature above and around a known 1970s burial with no similar collapse above the suspect location. In the saturated, clay-rich sediments of the site, 200MHz data offered no advantage over 400MHz data. Unprocessed 100MHz data shows a series of multiples in the known burial with no similar features in the suspect location. Processed 100MHz lines defined the shape of the collapse around the known burial to 2m depth, together with the geometry of the platform (1m depth) the gravedigger used in the 1970s to construct the site. In addition, processed 100MHz data showed both the dielectric contrast in and internal reflection geometry of the soil imported above the known grave. Thus the sequence, geometry, difference in infill and infill direction of the grave was reconstructed 30 years after burial. The suspect site showed no evidence of shallow or deep inhumation. Subsequently, the missing person������¢���¯���¿���½���¯���¿���½s body was found some distance from this site, vindicating the results and interpretation from ground-penetrating radar. The acquisition, processing, collapse feature and sequence stratigraphic interpretation of the known burial and empty (suspect) burial site may be useful proxies for other, similar investigations. GPR was used to evaluate this site within 3 hours of the survey commencing, using unprocessed data. An additional day of processing established that the suspect body did not reside here, which was counter to police and community intelligence.

Environmental Isotopes as Indicators for Ground Water Recharge to Fractured Granite

To assess the contribution of accumulated winter precipitation and glacial meltwater to the recharge of deep ground water flow systems in fracture crystalline rocks, measurements of environmental isotope ratios, hydrochemical composition, and in situ parameters of ground water were performed in a deep tunnel. The measurements demonstrate the significance of these ground water recharge components for deep ground water flow systems in fractured granites of a high alpine catchment in the Central Alps, Switzerland. Hydrochemical and in situ parameters, as well as d18O in ground water samples collected in the tunnel, show only small temporal variations. The precipitation record of d18O shows seasonal variations of ~14‰ and a decrease of 0.23‰ ± 0.03‰ per 100 m elevation gain. d2H and d18O in precipitation are well correlated and plot close to the meteoric water line, as well as d2H and d18O in ground water samples, reflecting the meteoric origin of the latter. The depletion of 18O in ground water compared to 18O content in precipitation during the ground water recharge period indicates significant contributions from accumulated depleted winter precipitation to ground water recharge. The hydrochemical composition of the encountered ground water, Na-Ca-HCO3-SO4(-F), reflects an evolution of the ground water along the flowpath through the granite body. Observed tritium concentrations in ground water range from 2.6 to 16.6 TU, with the lowest values associated with a local negative temperature anomaly and anomalous depleted 18O in ground water. This demonstrates the effect of local ground water recharge from meltwater of submodern glacial ice. Such localized recharge from glaciated areas occurs along preferential flowpaths within the granite body that are mainly controlled by observed hydraulic active shear fractures and cataclastic faults.

Distribution of Uranium Contamination in Weathered Fractured Saprolite/Shale and Ground Water

The objective of this study was to determine how structure, stratigraphy, and weathering influence fate and transport of contaminants (particularly U) in the ground water and geologic material at the Department of Energy (DOE) Environmental Remediation Sciences Department (ERSD) Field Research Center (FRC). Several cores were collected near four former unlined adjoining waste disposal ponds. The cores were collected, described, analyzed for U, and compared with ground water geochemistry from surrounding multilevel wells. At some locations, acidic U-contaminated ground water was found to preferentially flow in small remnant fractures weathering the surrounding shale (nitric acid extractable U [UNA] usually <50 mg kg–1) into thin (

Electrical Characterisation of SOI Substrates Incorporating WSix Ground Planes

Silicon-on-insulator (SOI) substrates incorporating tungsten silicide ground planes (GPs) have been shown to offer the lowest reported crosstalk figure of merit for application in mixed signal integrated circuits. The inclusion of the silicide layer in the structure may lead to stress or defects in the overlying SOI layers and resultant degradation of device performance. It is therefore essential to establish the quality of the silicon on the GPSOI substrate. MOS capacitor structures have been employed in this paper to characterize these GPSOI substrates for the first time. High quality MOS capacitor characteristics have been achieved with minority carrier lifetime of similar to 0.8 ms. These results show that the substrate is suitable for device manufacture with no degradation in the silicon due to stress or metallic contamination resulting from the inclusion of the underlying silicide layer.

Revealing the effect of angular correlation in the ground-state He wavefunction: a coincidence study of the transfer ionization process

A joint theoretical-experimental study of the transfer ionization process p + He -> H-0 + He2+ + e(-) is presented. For the first time all particles in the final state have been detected in triple coincidence. This fully differential measurement is in good agreement with a theoretical model where the target is described by a wavefunction containing both radial and angular correlation terms.