Epilepsy investigated non-invasively using Elecroencephalography (EEG) and Magnetoencephalography (MEG)

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Volume conductor modeling of the human head for electroencephalography (EEG) used in epilepsy

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Visualizing simulated electrical fields from electroencephalography and transcranial electric brain stimulation: a comparative evaluation

pre-printElectrical activity of neuronal populations is a crucial aspect of brain activity. This activity is not measured directly but recorded as electrical potential changes using head surface electrodes (electroencephalogram - EEG). Head surface electrodes can also be deployed to inject electrical currents in order to modulate brain activity (transcranial electric stimulation techniques) for therapeutic and neuroscientific purposes. In electroencephalography and noninvasive electric brain stimulation, electrical fields mediate between electrical signal sources and regions of interest (ROI). These fields can be very complicated in structure, and are influenced in a complex way by the conductivity profile of the human head. Visualization techniques play a central role to grasp the nature of those fields because such techniques allow for an effective conveyance of complex data and enable quick qualitative and quantitative assessments. The examination of volume conduction effects of particular head model parameterizations (e.g., skull thickness and layering), of brain anomalies (e.g., holes in the skull, tumors), location and extent of active brain areas (e.g., high concentrations of current densities) and around current injecting electrodes can be investigated using visualization. Here, we evaluate a number of widely used visualization techniques, based on either the potential distribution or on the current-flow. In particular, we focus on the extractability of quantitative and qualitative information from the obtained images, their effective integration of anatomical context information, and their interaction. We present illustrative examples from clinically and neuroscientifically relevant cases and discuss the pros and cons of the various visualization techniques

Realistic flight conditions on ground: new research facility for cabin ventilation

A new full-scale test bench was developed and set up at the German Aerospace Center in Göttingen to experimentally analyze novel ventilation approaches for aircraft under realistic thermodynamic boundary conditions. The new ground-based test rig represents a modern twin-aisle cabin layout characteristic for long-haul airliners. In addition to having a realistic cabin geometry, it also facilitates the experimental simulation of thermodynamic boundary conditions to study the performance of alternative ventilation concepts for different fight phases (e.g., climbing or cruising). The implemented fuselage elements as well as the foor are temperature controllable. Using this kind of mantle heating/cooling system allows dynamic changes of inner surface temperatures in a range covering the operationally relevant temperature and time scales. With this experimental set-up, a complete fight scenario (i.e., taxiing, climbing, cruising and descent) can be simulated thermodynamically.Thermal manikins were used during the studies to simulate the passenger's heat impact experimentally. Latest measurement techniques comprising the acquisition of fow velocities, fuid temperatures as well as surface temperatures were used. Based on these data, integral quantities like the mean temperature stratifcation and mean velocity levels near the manikins, the heat removal efciency as well as the predicted mean vote and the percentage of dissatisfed passengers were calculated to score the ventilation concepts in terms of passenger comfort for two diferent operational scenarios under steady boundary conditions

Side Differences of Thigh Muscle Cross-Sectional Areas and Maximal Isometric Muscle Force in Bilateral Knees with the Same Radiographic Disease Stage, but Unilateral Frequent Pain – Data from the Osteoarthritis Initiative

Objective To determine whether anatomical thigh muscle cross-sectional areas (MCSAs) and strength differ between osteoarthritis (OA) knees with frequent pain compared with contra-lateral knees without pain, and to examine the correlation between MCSAs and strength in painful vs painless knees. Methods Forty-eight subjects (31 women; 17 men; age 45–78 years) were drawn from 4,796 Osteoarthritis Initiative (OAI) participants, in whom both knees displayed the same radiographic stage (KLG2 or 3), one with frequent pain (most days of the month within the past 12 months) and the contra-lateral one without pain. Axial MR images were used to determine MCSAs of extensors, flexors and adductors at 35% femoral length (distal to proximal) and in two adjacent 5 mm images. Maximal isometric extensor and flexor forces were used as provided from the OAI database. Results Painful knees showed 5.2% lower extensor MCSAs (P = 0.00003; paired t-test), and 7.8% lower maximal extensor muscle forces (P = 0.003) than contra-lateral painless knees. There were no significant differences in flexor forces, or flexor and adductor MCSAs (P > 0.39). Correlations between force and MCSAs were similar in painful and painless OA knees (0.44 < r < 0.66). Conclusions Knees with frequent pain demonstrate lower MCSAs and force of the quadriceps (but not of other thigh muscles) compared with contra-lateral knees without knee pain with the same radiographic stage. Frequent pain does not appear to affect the correlations between MCSAs and strength in OA knees. The findings suggest that quadriceps strengthening exercise may be useful in treating symptomatic knee OA