Cutaneous nociceptive sensitization affects the directional discrimination – but not the 2-point discrimination

Background and aims Several pain conditions have been shown to reduce the discriminative abilities of external stimuli. The aim of this study was to investigate how cutaneous sensitization affects the tempo-spatial discrimination for both painful laser stimulation and mechanical stimulation. Methods Fifteen healthy subjects were presented with two different stimulation paradigms, a continuous line stimulation and a 2-point stimulation. Line stimulations were delivered in two different directions in lengths of 25, 50, 75, and 100 mm. Two-point distances from 0 to 100 mm were tested. The subjects reported the perceived intensity, and either direction (line stimulations) or number of perceived points (2-point stimulations). All stimuli were tested both before and after topical capsaicin (8% concentration) sensitization (30 min). Results All mechanical line stimulations were reported correctly before capsaicin and 3 stimulations (out of 240) were reported incorrectly after capsaicin. For the laser line stimulation, the directional discrimination threshold (DDT) was 69.5 mm before capsaicin and 76.3 mm after capsaicin. The 2-point discrimination threshold for laser stimulation was 70.3 mm before capsaicin and 68.0 mm after, for the mechanical stimuli it was 31.5 mm before capsaicin and 31.0 mm after capsaicin. The perceived intensities were increased for the laser line stimulations after capsaicin (linear mixed model (LMM), p < 0.001) and increased with stimulation length (LMM, p < 0.001). For mechanical stimuli, NRS was increased following capsaicin (LMM, p < 0.001). The intensities for both mechanical and laser 2-point stimuli increased after capsaicin and increased with distance between points (LMM, p < 0.01). Conclusions The findings show how cutaneous sensitization appears to affect directional discrimination to a larger extent than the 2-point discrimination. Implications This study is the first to investigate how directional discrimination is altered during sensitization. If such measures can be optimized they may provide a new method to probe the neural mechanisms in pain patients.

The Influence of Climate Change on CO2 and CH4 Concentration Near Closed Shaft – Numerical Simulations

Given the scientific consensus pointing to climate change, the more extreme weather events associated with this will lead to deeper pressure drops. As has already been stated, pressure drops are the main cause of gas flow from underground sites to the surface. This article presents the results of numerical simulations of the change in distribution of CO2 and CH4 near a closed mining shaft under the predicted baric tendency. Simulations have been undertaken by means of the FDS software package with the Pyrosim graphical interface – a CFD tool for fire and ventilation analysis. Assumptions have been based on previous results of in-situ measurements. The results (determined for a height of 1m above the ground) were compared to the following levels (later in the text comparison levels): for CO2 0.1%vol. according to Pettenkoffer’s scale and 2.5%vol. for CH4 as the half of Lower Explosive Limit (LEL). The results show that the deeper baric drops anticipated could lead to a wider spread of both greenhouse gases in the vicinity of the shaft, especially along the prevailing wind direction. According to the results obtained, CO2 and CH4 with concentrations above their comparison levels are expected at a distance greater than 50m from the shaft when wind is present for CO2 and at a distance of 4.5m for CH4. Subsequent analysis of the results enabled the determination of functions for describing the concentration of gases along the wind direction line under the projected pressure drop. The results relate to a particular case, although the model could easily be modified to any other example of gas emissions from underground sites.

Artificial moment method using attractive points for the local path planning of a single robot in complicated dynamic environments

SUMMARYA novel path planner is presented for the local path planning of a single robot (represented with R) in a complicated dynamic environment. Here a series of attractive points are computed based on attractive segments for guiding R to move along a shorter path. Each attractive segment is obtained by using the full environmental knowledge and will be used for several sampling times in general. A motion controller, which is designed based on artificial moments and a robot model that has a principal motion direction line(PMDline), makes R move closely to attractive points while away from obstacles. Attractive and repulsive moments are designed, which only make R's PMDline face toward attractive points and opposite to obstacles in general, as in most cases, R will move along its PMDline with its full speed. Because of the guidance of attractive points and R's full-speed motion, the global convergence is guaranteed. Simulations indicate that the proposed path planner meets the requirements of real-time property while can optimize R's traveling path.

Micro-Incremental Forming of Ti and Au Foils by Indentation Method

Ti and Au foils with a thickness of 10μm were formed by indenting at a place neighboring another indented place sequentially by means of a hemispherical diamond tool with a radius of 5μm. In this forming method, forming dies are not necessary and commercial equipments for nanoindentation can be used. Forming load and pitch were changed in single line forming and forming direction, line pitch and line number were changed in plural line forming, and bending angle was investigated. From the experimental results, bending angle of Ti foil was greater than that of Au one when same working conditions were employed. As the forming pitch increased, bending angle decreased. When the forming line pitch was changed, bending angle had the maximum peak at a pitch of 30μm by one-way forming path and 25μm by two-way forming path. Bending angle by one-way forming path was larger than that by two-way forming path. As forming line number increased, although bending angle increased, increment of them became smaller.