The phenomenology of pareidolia in healthy subjects and patients with left- or right-hemispheric stroke.

Pareidolia are perceptions of recognizable images or meaningful patterns where none exist. In recent years, this phenomenon has been increasingly studied in healthy subjects and patients with neurological or psychiatric diseases. The current study examined pareidolia production in a group of 53 stroke patients and 82 neurologically healthy controls who performed a natural images task. We found a significant reduction of absolute pareidolia production in left- and right-hemispheric stroke patients, with right-hemispheric patients producing overall fewest pareidolic output. Responses were categorized into 28 distinct categories, with 'Animal', 'Human', 'Face', and 'Body parts' being the most common, accounting for 72% of all pareidolia. Regarding the percentages of the different categories of pareidolia, we found a significant reduction for the percentage of "Body parts" pareidolia in the left-hemispheric patient group as compared to the control group, while the percentage of this pareidolia type was not significantly reduced in right-hemispheric patients compared to healthy controls. These results support the hypothesis that pareidolia production may be influenced by local-global visual processing with the left hemisphere being involved in local and detailed analytical visual processing to a greater extent. As such, a lesion to the right hemisphere, that is believed to be critical for global visual processing, might explain the overall fewest pareidolic output produced by the right-hemispheric patients.

Feasibility to Measure Tissue Oxygen Saturation Using Textile-Integrated Polymer Optical Fibers.

Tissue oxygen saturation (StO2) is a crucial factor in the aetiology of pressure injury (PI), since hypoxia leads to necrotization. Pressure on the tissue occludes blood circulation and reduces the StO2, resulting in hypoxia. PI causes severe suffering, heals slowly and is expensive to treat. Hence it is important to prevent PI by detecting hypoxia, e.g., by near-infrared spectroscopy (NIRS) monitoring of StO2. For this, the NIRS device has to be wearable for a long time and it is crucial that it provokes no pressure itself. An integration of optical fibres into a textile achieves this. The aim was to investigate the feasibility of such a textile NIRS device.Knots and loops were tested as textile light emitters (LEs) or detectors (LDs) on a phantom. The light coupling efficiency of the LEs and LDs was investigated.Results show that knots perform similarly to loops. More loops per fibre increase efficiency both in LEs and in LDs. The best trade-off is at 3 loops. LEs are slightly more efficient than LDs, with an average attenuation from baseline of about -2 dB for loops of 0.5 mm diameter. Adding fibres multiplies the signal by the number of fibres. Inclusions mimicking hypoxia in phantoms were successfully identified. In-vivo arm occlusion tests showed the expected decrease in StO2. This shows feasibility of optical fibres in a textile to prevent PI.

Numerical Optimisation of a NIRS Device for Monitoring Tissue Oxygen Saturation.

The present work aims to develop a wearable, textile-integrated NIRS-based tissue oxygen saturation (StO2) monitor for alerting mobility-restricted individuals - such as paraplegics - of critical tissue oxygen de-saturation in the regions such as the sacrum and the ischial tuberosity; these regions are proven to be extremely susceptible to the development of pressure injuries (PI).Using a combination of numerical methods including finite element analysis, image reconstruction, stochastic gradient descent with momentum (SGDm) and genetic algorithms, a methodology was developed to define the optimal combination of wavelengths and source-detector geometry needed for measuring the StO2 in tissue up to depths of 3 cm. The sensor design was optimised to account for physiologically relevant adipose tissue thicknesses (ATT) between 1 mm and 5 mm. The approach assumes only a priori knowledge of the optical properties of each of the three tissue layers used in the model (skin, fat, muscle) based on the absorption and scattering coefficients of four chromophores (O2Hb, HHb, H2O and lipid).The results show that the selected wavelengths as well as the source-detector geometries and number of sources and detectors depend on ATT and the degree and volume of the hypoxic regions. As a result of a genetic algorithm used to combine the various optimised designs into a single sensor layout, a group of four wavelengths was chosen, coinciding with the four chromophores and agreeing very well with literature. The optimised number of source points and detector points and their geometry resulted in good reconstruction of the StO2 across a wide range of layer geometries.

Materials used to simulate physical properties of human skin.

BACKGROUND: For many applications in research, material development and testing, physical skin models are preferable to the use of human skin, because more reliable and reproducible results can be obtained. PURPOSE: This article gives an overview of materials applied to model physical properties of human skin to encourage multidisciplinary approaches for more realistic testing and improved understanding of skin-material interactions. METHODS: The literature databases Web of Science, PubMed and Google Scholar were searched using the terms 'skin model', 'skin phantom', 'skin equivalent', 'synthetic skin', 'skin substitute', 'artificial skin', 'skin replica', and 'skin model substrate.' Articles addressing material developments or measurements that include the replication of skin properties or behaviour were analysed. RESULTS: It was found that the most common materials used to simulate skin are liquid suspensions, gelatinous substances, elastomers, epoxy resins, metals and textiles. Nano- and micro-fillers can be incorporated in the skin models to tune their physical properties. CONCLUSION: While numerous physical skin models have been reported, most developments are research field-specific and based on trial-and-error methods. As the complexity of advanced measurement techniques increases, new interdisciplinary approaches are needed in future to achieve refined models which realistically simulate multiple properties of human skin.

CO2 and O2 concentrations in integral motorcycle helmets.

Inhaling air which contains excess CO2 and/or is oxygen-deficient is known to present health risks and to diminish human cognitive abilities. The average CO2 concentrations relevant to a motorcyclist wearing an integral helmet were measured 20 years ago and found to be alarmingly large. The purpose of the present study was to examine gas concentrations typically inhaled by a motorcyclist. Average concentrations of CO2 near the upper lip for persons (n = 4) wearing integral motorcycle helmets were measured in the laboratory and the field to facilitate comparison to previous work, and similarly high average concentrations were found: above 2% when stationary, well below 1% for speeds of 50 km/h or more. Very good agreement was obtained between laboratory and field measurements. Detailed measurements of the time-dependent CO2 concentrations passing through a mouthpiece for mouth-breathing showed inhaled levels slightly over half of the corresponding average concentrations, including 1.3+/-0.3% at standstill, though higher concentrations (4% or more) were inhaled at the beginning of each breath. Opening the visor at standstill had on average no effect. At a speed of 50 km/h the inhaled CO2 concentration resembles that for a person without a helmet in still air, at about 0.2%. The oxygen deficiency is generally equal to the CO2 concentration, and could also contribute negatively to a motorcyclist's cognitive abilities.

Determination of the ultraviolet protection factor of textile materials:measurement precision.

BACKGROUND: There is much interest in the use of textiles for sun protection. In vitro test methods are frequently used to assess the degree of protection to solar ultraviolet radiation of textile materials. It is, however, of paramount importance that methods are clearly described and that the precision of these methods is determined such that comparison between laboratories can be performed. An in vitro method for the determination of the Ultraviolet Protection Factor (UPF) is described in a new European Standard and is referred to as prEN 13758. Thirty experts from 11 European member states, forming a working group of the European Standardization Commission (CEN), have developed this method in consensus. In this paper the reliability of this test method for the determination of the UPF of textiles worn in close proximity to the skin and in a relaxed and dry state is studied. METHODS: For the determination of the precision of the test method, eight laboratories, using nine different measuring devices located in five different countries, have measured 14 textile materials of various types of construction and levels of UVR protection. Statistical analysis of the results has been performed according to ISO 5725. RESULTS: The repeatability standard deviation of the described method is independent of the UPF in the range 1-70 and is 1.36. The reproducibility standard deviation, however, clearly increases with the level of UPF. CONCLUSIONS: For high UPF values, differences between laboratories, due to factors such as different operators, equipment and calibration, can become important. This makes classification of high UPF materials questionable.

Spatial variability of different fractions of particulate matter within an urban environment and between urban and rural sites.

The spatial variability of different fractions of particulate matter (PM) was investigated in the city of Basel, Switzerland, based on measurements performed throughout 1997 with a mobile monitoring station at six sites and permanently recorded measurements from a fixed site. Additionally, PM10 measurements from the following year, which were concurrently recorded at two urban and two rural sites, were compared. Generally, the spatial variability of PM4, PM10, and total suspended particulates (TSP) within this Swiss urban environment (area = 36 km2) was rather limited. With the exception of one site in a street canyon next to a traffic light, traffic density had only a weak tendency to increase the levels of PM. Mean PM10 concentration at six sites with different traffic densities was in the range of less than +/- 10% of the mean urban PM10 level. However, comparing the mean PM levels on workdays to that on weekends indicated that the impact of human activities, including traffic, on ambient PM levels may be considerable. Differences in the daily PM10 concentrations between urban and more elevated rural sites were strongly influenced by the stability of the atmosphere. In summer, when no persistent surface inversions exist, differences between urban and rural sites were rather small. It can therefore be concluded that spatial variability of annual mean PM concentration between urban and rural sites in the Basel area may more likely be caused by varying altitude than by distance to the city center.

Arotinoid ethyl ester (Ro 13-6298): a long term pilot study in various dermatoses.

The arotinoid ethyl ester Ro 13-6298 is a third generation retinoid shown to be thousand-fold more potent than etretinate (Tigason, Tegison) in animal testing and in human therapy. In an open uncontrolled trial, we treated 57 patients suffering from psoriasis (32) and various severe skin disorders (25) with daily doses ranging from 20 to 150 micrograms, during 1 to 130 weeks (mean = 12 weeks). Four patients were treated for 1 year or more. Given in micrograms per kg range, Ro 13-6298 showed a spectrum of clinical activity and mucocutaneous side effects similar to that of etretinate given in mg per kg range. One patient developed diffuse idiopathic skeletal hyperostosis after 2 years of continuous therapy. No increase in either serum triglycerides or cholesterol levels was observed, even in patients treated for 33 to 130 weeks. This might prove to be an advantage of this new retinoid. Furthermore, this series suggests that potent mucocutaneous (therapeutical and side) effects are not necessarily linked to all other signs of retinoid toxicity.

Cellular retinoic acid- but not cellular retinol-binding protein is elevated in psoriatic plaques.

Cellular retinoid binding proteins are thought to be involved in the molecular action of retinoids, a family of compounds successfully used in the treatment of psoriasis. Therefore, both cellular retinol (CRBP)- and retinoic acid (CRABP)-binding proteins were analyzed in psoriatic skin. Three facts emerged from our study: both CRABP and CRBP are detectable in the skin of psoriatic patients; qualitatively, they both appear similar to the corresponding proteins of normal human skin, in terms of their elution profile and apparent Kd; and quantitatively, only CRABP was found to be 3 times higher in psoriatic plaques as compared to either nonlesional skin of psoriatic patients or the skin of normal subjects. Since psoriatic plaques are particularly responsive to systemic retinoids, specifically to retinoic acid analogues, our results suggest for the first time a link between the levels of CRABP and the responsiveness of a nonneoplastic hyperproliferative tissue to systemic administration of retinoids in the human.