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Structural cerebral MRI analysis in patients with neurological diseases usually requires T1-weighted datasets for tissue segmentation. For this purpose, synthetic T1-weighted images which are constructed from quantitative maps of the underlying tissue parameters such as the T1 relaxation time and the proton density (PD) may provide advantages over conventional datasets. However, in some cases synthetic images may suffer from specific artifacts, hampering accurate tissue segmentation. The goal was to improve a previously described method for the calculation of synthetic magnetization-prepared rapid gradient-echo (MP-RAGE) datasets from quantitative T1 and PD maps. Improvements comprise a B0-correction for the water-selective excitation pulses employed in T1-mapping and the use of T1-based pseudo-PD maps. Synthetic T1-weighted MP-RAGE datasets were calculated, using the standard and the improved algorithm, for 10 patients with focal epilepsy (caused by focal cortical dysplasia in 9), 10 patients with multiple sclerosis and 10 healthy control subjects and segmented with the Freesurfer toolbox. Visual inspection disclosed that segmentation of the standard synthetic datasets was inaccurate in 6 out of 10 patients with epilepsy, 7 out of 10 patients with multiple sclerosis and 7 out of 10 healthy control subjects, while the improved synthetic datasets resulted in adequate segmentation outcomes in the majority of cases. Only for one patient with multiple sclerosis and one with epilepsy, segmentation in basal temporal regions was not sufficient. Furthermore, data based on the standard algorithm showed strong signal non-uniformities in basal regions. This effect was not present in the improved synthetic datasets.

This work presents the first experimental results obtained with a single stage absorption heat transformer (AHT), which was operated with the working fluid water/ionic liquid. The ionic liquid (IL) used in this work was 1-ethyl-3-methyl-imidazolium methanesulfonate (EMIM OMs). Several sets of experiments were conducted by varying the inlet temperatures of the external circuits and the internal flow rates. The coefficient of performance (COP) decreases with increasing high temperature and decreasing medium temperature. At higher internal flow rates, the COP increases due to the improved efficiency of the solution heat exchanger and higher heat flows in the apparatuses. The comparison of the experimental results with simulation results shows a good agreement at low temperature lifts. At higher temperature lifts and lower heat flows in the apparatuses, the influences of heat losses, pump duties and uncertainties let the experimental results diverge from the simulated ones. The highest experimental COP was 0.43 at a heat flow of 5.5 kW in the absorber and a temperature lift of 18.5 K. The highest temperature lift was 47 K. The corresponding COP was 0.27 and the heat flow in the absorber 1.7 kW.

Objective Patients with temporal lobe epilepsy caused by autoimmune limbic encephalitis (AI-TLE) clinically resemble patients with temporal lobe epilepsy with non-autoimmune etiologies (NAI-TLE) but have a different prognosis and require specific adjusted therapies. The objective of this study was to investigate whether patients with these forms of TLE can be discerned by means of neuropsychological assessment. Methods Data from 103 patients with TLE (n = 39 with AI-TLE and n = 64 with NAI-TLE, including n = 39 with hippocampal sclerosis [HS] and n = 25 with low-grade epilepsy-associated tumors [LEAT]) and 25 healthy controls who underwent comprehensive neuropsychological assessments were analyzed retrospectively. The neuropsychological characteristics (mean z-scores) were compared between groups using one-way ANOVA, independent-samples t-tests, and discriminant function analysis (DFA). Results The groups of patients with TLE showed significantly lower performance in attentional, visuospatial, verbal memory, and nonverbal memory functions compared to the healthy controls. Solely in the domain of executive functions, patients with AI-TLE showed significantly lower performance compared to patients with NAI-TLE regarding cognitive flexibility (p = 0.002) and verbal fluency (p = 0.018). Moreover, the DFA identified cognitive flexibility to be most appropriate to differentiate between patients with AI-TLE and patients with HS. Group membership was correctly predicted through neuropsychological assessment alone in 66.7% of the patients using cross-validation. Significance We were able to identify specific neuropsychological features in our sample of patients with AI-TLE. While all groups of patients with TLE showed the expected TLE-typical memory impairments, significant differences between patients with AI-TLE and NAI-TLE were present only in the cognitive domain of executive functions. This finding facilitates the choice of suitable psychometric tests in clinical routine and, thus, the clinical differential diagnosis between these entities.

Purpose Firstly, to evaluate the validity of a neuropsychological test battery in epilepsy patients, i.e. whether its tests sufficiently allow the assessment of the required cognitive domains in this specific group. Secondly, to examine its ability to differentiate between cognitive profiles of different subgroups of focal epilepsy. Methods The test battery suggested by the German ILAE Chapter was performed on 207 epilepsy patients, and its factor structure was investigated by principal component analysis (PCA). To further examine its accuracy in two matched subgroups of patients with temporal lobe epilepsy (TLE, n = 35) and frontal lobe epilepsy (FLE, n = 35), a discriminant function analysis (DFA) was used. Results PCA revealed eleven interpretable factors, accounting for 69.1% of total variance: Divided Attention, Reaction Time, Verbal Learning, Verbal Memory, Contextual Memory, Short-term- and Working Memory, Visuospatial Functioning, Space Perception, Verbal Fluency, Response Monitoring and Cognitive Flexibility. DFA identified six test to be most appropriate to discern TLE from FLE: WMS-IV Logical Memory, recognition; WMS-R Digit Span, backwards; VLMT, repetitions; VOSP Silhouettes; VLMT, delayed recall; and RWT Phonemic verbal fluency. Group membership was correctly predicted for 78.6% of patients using cross-validation. Conclusions As neuropsychological assessments are central in clinical decision-making in presurgical work-up of epilepsy patients, the appropriateness of the test battery in use is essential. The majority of cognitive domains are sufficiently measurable by the test battery and it is highly sensitive to differentiate between the cognitive profiles of TLE and FLE. However, the selection of tests assessing nonverbal memory functions requires further improvement.

Since two decades, water + ionic liquids (ILs) are considered as new working pairs for absorption cycles. To estimate the performance of the cycles, thermophysical properties, and especially the vapor liquid equilibrium (VLE) behavior has to be known. Therefore, the vapor pressure of the possible working pairs water + 1-ethyl-3-methylimidazolium methanesulfonate ([EMIM][OMs]), water + 1-ethyl-3-methylpyridinium methanesulfonate ([E3MPy][OMs]) and water + 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf]) have been measured over the whole concentration range and in the temperature range of T = (293.15–353.15) K. The vapor pressure data have been compared with the ones of the three binary mixtures water + diethylmethylammonium methanesulfonate ([DEMA][OMs]), water + diethylmethylammonium trifluoromethanesulfonate ([DEMA][OTf]) and water + 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]). The results indicate that the anion is essential for the vapor pressure reduction of an IL. The water affinity decreases in the following order [OAc]− > [OMs]− > [OTf]−. As the performance of an absorption cycle is mainly affected by a high vapor pressure reduction, this result leads to a first selection of possible absorbents. The vapor pressure measurements were used to estimate temperature-dependent NRTL coefficients. These parameters have been employed to predict the excess molar enthalpies of the binary mixtures. A comparison with experimental data found in literature shows a good agreement. Besides the thermodynamic suitability, the thermal stability of the working pair is essential for the possible use in absorption cycles. Therefore thermogravimetric analyses (TGA) are also presented and indicate that water + [EMIM][OMs] and water + [E3MPy][OMs] could be considered as new working pairs in absorption heat transformers.

Human subjects were trained with neurofeedback (NFB) to enhance the power of narrow-band gamma oscillations in circumscribed regions of early visual cortex. To select the region and the oscillation frequency for NFB training, gamma oscillations were induced with locally presented drifting gratings. The source and frequency of these induced oscillations were determined using beamforming methods. During NFB training the power of narrow band gamma oscillations was continuously extracted from this source with online beamforming and converted into the pitch of a tone signal. We found that seven out of ten subjects were able to selectively increase the amplitude of gamma oscillations in the absence of visual stimulation. One subject however failed completely and two subjects succeeded to manipulate the feedback signal by contraction of muscles. In all subjects the attempts to enhance visual gamma oscillations were associated with an increase of beta oscillations over precentral/frontal regions. Only successful subjects exhibited an additional marked increase of theta oscillations over precentral/prefrontal and temporal regions whereas unsuccessful subjects showed an increase of alpha band oscillations over occipital regions. We argue that spatially confined networks in early visual cortex can be entrained to engage in narrow band gamma oscillations not only by visual stimuli but also by top down signals. We interpret the concomitant increase in beta oscillations as indication for an engagement of the fronto-parietal attention network and the increase of theta oscillations as a correlate of imagery. Our finding support the application of NFB in disease conditions associated with impaired gamma synchronization.

New working pairs of room-temperature ionic liquids (RTILs) and water offer an opportunity to replace the highly corrosive and partly immiscible working pair of lithium bromide (LiBr) and water in absorption cycles like the absorption chiller. To estimate the suitability of these working pairs, the knowledge of thermophysical properties is inevitable. Due to the lack of literature data the following properties of two RTIL–water mixtures will be presented in this paper. Vapor–liquid equilibria (VLE) of the binary mixture of water + diethylmethylammonium trifluoromethanesulfonate ([DEMA][OTf]) and the ternary mixture of water + [DEMA][OTf] + diethylmethylammonium methanesulfonate ([DEMA][OMs]) were measured in the temperature range T = (293.15 to 353.15) K. The VLE measurements were carried out by Fourier transform infrared (FTIR) spectroscopy in a dynamic cell. The experimental VLE data were fitted with the nonrandom two-liquid (NRTL) model. Heat capacities, densities, and viscosities of the binary mixture...

This work details the results of a study into the relationship between pressure drop and liquid saturation in mist (or coalescing) filters. Liquid saturation (clogging) in mist filters is of critical importance as it is directly related to filter efficiency and flow resistance. Experiments were conducted to determine steady-state saturation and pressure drop values in commonly used oleophillic fibrous filter media, using a range of different combinations of face velocity and number of layers of media within the filter element. Several empirical relationships for saturation and pressure drop were derived based on the relationships found. In addition, a capillary-based saturation model has been described and fitted to the experimental data. A good agreement between the model and data was obtained when an empirically fitted term was added. Equations were developed which allow such variables to be determined from known parameters.

Neurofeedback (NFB) became a popular tool during the last decades, and seems to prove the brain’s ability to influence its own activity level when internal processes are made accessible. A rich literature indicates that humans and animals are able to learn to influence diverse brain parameters, oscillatory patterns as well as the BOLD signal. Even though there is much known about oscillatory processes, it is still unclear how the brain manages to influence its own oscillatory activity. We developed a novel MEG technique for the real-time analysis of MEG source data to investigate that question. Our method extracts the power of ongoing oscillatory activity from a region of interest at the source, not at the sensor level, using the weighted information of all 275 MEG sensors in a real-time Beamforming procedure. The extracted power of oscillations in a particular frequency range is then used as the feedback signal. To examine whether and how the brain can control the level of oscillatory activity in the high frequency band (>40 Hz, gamma band) we converted the gamma power into the pitch of a tone and trained subjects to modulate the pitch. Subsequent periods with and without feedback training were compared and the spectral and spatial parameters of oscillatory brain activity determined. Our pilot study includes 5 healthy subjects that all completed nine sessions of NFB training, each lasting about 50 minutes. The data suggests that 4 subjects were able to change high frequency oscillations in visual cortex in particular frequency bands. The distances between the region of interest and task related changes are less than 2 cm in the successful subjects. The task related changes vary between participants. Some frequency patterns could resemble those modulated under focused attention.