Comparison of electrohysterogram signal measured by surface electrodes with different designs: A computational study with dipole band and abdomen models

Non-invasive measurement of uterine activity using electrohysterogram (EHG) surface electrodes has been attempted to monitor uterine contraction. This study aimed to computationally compare the performance of acquiring EHG signals using monopolar electrode and three types of Laplacian concentric ring electrodes (bipolar, quasi-bipolar and tri-polar). With the implementation of dipole band model and abdomen model, the performances of four electrodes in terms of the local sensitivity were quantifed by potential attenuation. Furthermore, the efects of fat and muscle thickness on potential attenuation were evaluated using the bipolar and tri-polar electrodes with diferent radius. The results showed that all the four types of electrodes detected the simulated EHG signals with consistency. That the bipolar and tri-polar electrodes had greater attenuations than the others, and the shorter distance between the origin and location of dipole band at 20dB attenuation, indicating that they had relatively better local sensitivity. In addition, ANOVA analysis showed that, for all the electrodes with diferent outer ring radius, the efects of fat and muscle on potential attenuation were signifcant (all p<0.01). It is therefore concluded that the bipolar and tri-polar electrodes had higher local sensitivity than the others, indicating that they can be applied to detect EHG efectively

Spatiotemporally resolved imaging of streamer discharges in air generated in a wire-cylinder reactor with (sub)nanosecond voltage pulses

We use (sub)nanosecond high-voltage pulses to generate streamers in atmospheric-pressure air in a wire-cylinder reactor. We study the effect of reactor length, pulse duration, pulse amplitude, pulse polarity, and pulse rise time on the streamer development, specifically on the streamer distribution in the reactor to relate it to plasma-processing results. We use ICCD imaging with a fully automated setup that can image the streamers in the entire corona-plasma reactor. From the images, we calculate streamer lengths and velocities. We also develop a circuit simulation model of the reactor to support the analysis of the streamer development. The results show how the propagation of the high-voltage pulse through the reactor determines the streamer development. As the pulse travels through the reactor, it generates streamers and attenuates and disperses. At the end of the reactor, it reflects and adds to itself. The local voltage on the wire together with the voltage rise time determine the streamer velocities, and the pulse duration the consequent maximal streamer length

Sensitivity of MEG and EEG to Source Orientation

An important difference between magnetoencephalography (MEG) and electroencephalography (EEG) is that MEG is insensitive to radially oriented sources. We quantified computationally the dependency of MEG and EEG on the source orientation using a forward model with realistic tissue boundaries. Similar to the simpler case of a spherical head model, in which MEG cannot see radial sources at all, for most cortical locations there was a source orientation to which MEG was insensitive. The median value for the ratio of the signal magnitude for the source orientation of the lowest and the highest sensitivity was 0.06 for MEG and 0.63 for EEG. The difference in the sensitivity to the source orientation is expected to contribute to systematic differences in the signal-to-noise ratio between MEG and EEG.National Institutes of Health (U.S.) (Grant NS057500)National Institutes of Health (U.S.) (Grant NS037462)National Institutes of Health (U.S.) (Grant HD040712)National Center for Research Resources (U.S.) (P41RR14075)Mind Research Networ

HEAT CAPACITY OF FOUR MANGANESE DOUBLE CHLORIDES

Les chaleurs spécifiques de Cs3MnCl5, Cs2MnCl4.2 H2O, K4MnCl6 et α-Cs2MnCl4 ont été mesurées aux températures entre 0,05 et 3 °K. Pour chacun des quatre composés, la courbe de la chaleur spécifique montre une anomalie pointue. Des mesures des susceptibilités ont montré que ces anomalies sont causées par des transitions de phase antiferromagnétiques. En raison de l'état S de l'ion Mn2+, les résultats seront interprétés en terme du modèle Heisenberg.The heat capacities of Cs3MnCl5, Cs2MnCl4.2 H2O, K4MnCl6 and α-Cs2MnCl4 have been measured at temperatures between 0.05 and 3 °K. Each of the four salts shows a sharp anomaly in the heat capacity curve. Susceptibility measurements showed that these anomalies are due to antiferromagnetic phase transitions. In view of the S-state of the Mn2+ ion, the results will be explained in terms of the Heisenberg model

Vision Paper : Integrating VV&A methods and cost-effectiveness analysis in the acquisition process for training simulation solutions

Simulation is an important technology that enables NATO and its member nations to train their soldiers. The benefits of simulation-based training include saving of time, money, and even lives, when training for unsafe scenarios. Simulation also facilitates joint and combined training. Moreover, simulation-based training is capable of expanding the limits of live training, thus facilitating larger exercises. The acquisition of valid and cost-effective training simulation solutions is crucial to the mission-readiness of our armed forces, in particular when available funding and resources are limited. This paper presents our vision of the defence acquisition processes for simulation systems by integration with verification, validation and accreditation (VV&A) methods and cost-effectiveness analysis (CEA), in order to assure that a valid and cost-effective training simulation solution is acquired. We envision supporting the whole acquisition process (e.g., stating the need, training needs analysis, requirements analysis, evaluation and selection, and acceptance of assets), taking all other cost aspects of the training simulation solution lifecycle into account (e.g., deployment, maintenance, re-use, retirement). All three of the processes mentioned above include multiple activities and tasks, and they require large amounts of information. We propose to combine activities where possible and to ensure that inputs and outputs match. For example, a good set of requirements based on the user needs is input for the acquisition process, but also important as one of the starting points of VV&A, as well as for CEA. The authors hope to further develop the ideas presented in this vision paper. This future work should be performed in close cooperation with ministry of defence (MoD) procurement organizations and should also engage with the wider NATO research community, in particular the SAS panel and the NMSG. The presentation of the initial concept to the SAS-095 task-group on Cost-benefit Analysis of Military Training is seen as a first step in that direction

Oceanic carbon and water masses during the Mystery Interval: A model-data comparison study

The 'Mystery Interval' (17.5-14.5 ka BP) is characterized by a large decline in atmospheric Delta C-14 synchronous with an increase in atmospheric CO2. The most widely accepted hypothesis to explain these observed shifts involves the existence of an isolated 'old' ocean carbon reservoir that was subsequently ventilated. Here we use the UVic Earth System Climate Model to locate a potential carbon rich and Delta C-14 depleted water mass under 17.5 ka BP boundary conditions. We then investigate two mechanisms for the potential ventilation of such a reservoir, namely the weakening of the North Atlantic Meridional Overturning due to iceberg calving and latitudinal shifts in Southern Hemisphere Westerlies (SHW) due to southern hemispheric warming. We find that simulations derived from an equilibrium state forced with present-day SHW and moderate North Atlantic Deep Water (NADW) formation are in better agreement with atmospheric and ocean Delta C-14 reconstructions than simulations derived from an equilibrium state forced with a northward shifted SHW belt resulting in a shut-down of the Atlantic Meridional Overturning and formation of North Pacific Deep Water. For simulations with present-day SHW, the oldest water masses are found in the North Pacific, although the Southern Ocean cannot be ruled out as a potential 'Mystery Reservoir'. According to our simulations, the strength of Atlantic overturning is the dominant mechanism in increasing the ocean-atmosphere carbon flux, while shifting SHW results in a rearrangement of deep ocean carbon largely between the Atlantic and Pacific basins. In our 'best case' scenario, the model can account for 58% of the atmospheric CO2 increase and 48% of the atmospheric Delta C-14 decline. While the rate of ventilation and the age of ventilated water masses are comparable with observations, the ventilation in the model could not be sustained long enough to account for the full excursion seen in paleodata

HEAT CAPACITY MEASUREMENTS ON THE DILUTED ISING SYSTEM Cs3CopZn1-pCl5

Des mesures de la chaleur spécifique sur le système Cs3CopZn1-pCl5 montrent que TN dépend de p d'une manière qui correspond nettement avec les calculs sur le modèle d'Ising pour un réseau cubique simple et pour une dilution au hasard des ions magnétiques.Heat capacity measurements on the system Cs3CopZn1-pCl5 show a dependence of TN on p which agrees with calculations on the randomly diluted simple cubic (s. c.) Ising model