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The focus on transient engine operation will increase to fulfill future emission requirements in the commercial vehicle sector. Accordingly, the transient turbocharger matching process is becoming increasingly important. The one-dimensional fluid dynamics (1D-CFD) simulation is established as an important development tool for matching the exhaust gas turbocharger to a combustion engine. The optimization of the modeling methodology of the combustion process and the turbocharger modeling are two key parameters to improve the reliability of the dynamic engine process simulation. In this paper, the advanced turbocharger (TC) methodology is described. This includes the determination of the adiabatic turbocharger performance from conventional hot gas test stand (HGS) measurement data, the derivation of an one-dimensional (1D) turbocharger heat transfer model and a method to physically extend the turbine map range. The adiabatic efficiencies of the turbocharger are determined with a model-based heat transfer correction of the conventional measured efficiencies from HGS measurement data. These adiabatic efficiency maps were used as a baseline to extend the conventional TC model with a heat transfer model taking into account of the engine boundary conditions in terms of temperature, pressure and mass flow rate. To assess the temperature distribution and the thermal inertia of the TC main components, in both stationary and transient engine operations, the variable geometry turbine (VGT) turbocharger hardware, installed on a medium-duty diesel engine, was equipped with several thermocouples on all accessible surfaces to make comprehensive surface temperature surveys. A 1D lumped capacitance heat transfer model (HTM) of the VGT TC was developed and validated against the experimental data from the engine test bench. To complete the advanced TC modeling, the turbine map is extended using experimental measurement data, based on extended HGS measurements, in combination with mathematically supported extrapolation. The results from the advanced turbocharger simulation methodology significantly improves the prediction of the temperature drop over the turbine in comparison to the conventional adiabatic TC simulation methodology. The validated heat transfer model also allows the analysis of the heat flow breakdown of the turbocharger. Based on the advanced turbocharger model, a tool for the improved transient turbocharger-engine matching process is given.

Referenzwerte/-intervalle dienen in der Medizin generell einer diagnostischen Einordnung von am Patienten erhobenen Befunden. Fur die Schlafmedizin sind nach den Empfehlungen der American Academy of Sleep Medicine (AASM) eine Reihe von Variablen im Befundbericht einer polysomnographischen Untersuchung mitzuteilen. Dazu zahlen respiratorische Ereignisse, Bewegungsereignisse, kardiale Ereignisse, Arousalereignisse sowie Parameter der Schlafarchitektur. In der vorliegenden Arbeit werden Referenzwerte speziell fur Parameter zur Charakterisierung der Schlafarchitektur vorgestellt. Es werden methodische Aspekte der Konstruktion von Referenzwerten (statistische und Auswahl der Referenzstichprobe), Darstellungsmoglichkeiten (tabellarisch und grafisch) sowie Gultigkeitsbereiche (Verwendung unterschiedlicher Referenzwerte fur Daten, die nach dem Standard gemas Rechtschaffen und Kales und dem AASM-Standard erhoben und ausgewertet wurden) diskutiert.

Torsten Eggert, Hans Dorn, Heidi Danker-Hopfe Charité – Universitätsmedizin Berlin, Competence Centre of Sleep Medicine, Berlin, GermanyCorrespondence: Heidi Danker-Hopfe, Email heidi.danker-hopfe@charite.dePurpose: The quantitative sleep EEG has been considered as electroencephalographic “fingerprint”, ie, it is stable within but differs between individuals. So far, however, almost all studies addressing this aspect have been conducted in young men. It was therefore of interest to know whether the sleep EEG fingerprint concept holds true in older samples of both sexes.Patients and Methods: Data from three different subsamples of 30 healthy individuals each were reused for the present secondary analysis (young men (YM) = 25.6 ± 2.4 years, elderly men (EM) = 69.1 ± 5.5 years, elderly women (EW) = 67.8 ± 5.7 years). Individuals slept ten times in the sleep laboratory, resulting in a total of 900 study nights. However, to avoid misinterpretation due to intervention-related changes in sleep EEG power spectra, only the 3 sham nights without any intervention were included, reducing the datasets to 270. To determine stability of NREM sleep EEG power spectra between sham night pairs, within- and between-subject Manhattan distance measures were computed separately by sample.Results: Regardless of subsample and sham night pair, lowest distance measures, ie, largest similarity, were observed for within-subject power spectra comparisons (range of mean distance measures for EW from 3.82 to 4.06, for EM from 3.55 to 3.63, and for YM from 3.04 to 3.62). Moreover, intraindividual similarity did not differ substantially between samples. Between-subject power spectra distance measures were considerably larger (range of mean distance measures for EW from 12.95 to 13.15, for EM from 12.21 to 12.57, and for YM from 10.33 to 10.78) and varied significantly between young and elderly individuals.Conclusion: The present results support the view that the sleep EEG power spectrum is an individual trait-like characteristic that remains unique up until old age. This finding may help to increase the sensitivity in measuring intervention effects.Keywords: sleep EEG power spectra, aging and sleep, heritability of sleep EEG, electroencephalographic fingerprint, trait-like quantitative EEG characteristics, individuality of sleep EEG

The one-dimensional computational fluid dynamics (1D-CFD) simulation is an important development tool for improving the matching process of the exhaust gas turbocharger with a combustion engine. To meet future emission requirements of commercial vehicles, an increasing focus on transient operation conditions is given. For example, a faster boost pressure build-up allows higher exhaust gas recirculation rates during load steps—improving transient nitrogen oxides ($$\hbox {NO}_x$$) emissions. According to this, the matching process of the turbocharger focuses increasingly on the transient operation conditions of combustion engines. To increase the quality of the dynamic engine process simulation, the simulation model should be optimized with regard to the quality of the engine’s high-pressure process including emissions as well as the turbocharger modeling methodology. This paper focuses on the application of an approach that combines a data-based combustion model for the $$\hbox {NO}_x$$ and soot values and the high-pressure part of the working process with a physical description of the gas exchange. To generate the data for the combustion model, an extensive measurement campaign of all relevant parameters was carried out on a medium-duty diesel single-cylinder research engine. The developed model was integrated into a multi-cylinder engine (MCE) simulation environment and validated on the basis of corresponding MCE measurements. The sensitivities of the model were examined for the input parameters. The data-based combustion model demonstrates a high accuracy in emissions and high-pressure working process modeling both in the wide range of the engine map and under transient operating conditions as well as for different engine calibration strategies. As a result, a good baseline for the improved transient combustion simulation is provided.

Background The manipulation of specific brain oscillations by applying transcranial electrical stimulation techniques in order to enhance memory processes during sleep has become an intriguing field of research. A seminal study found a positive effect of slow-oscillatory transcranial direct current stimulation (so-tDCS) on sleep-dependent consolidation of declarative memories. Since then several studies have tried to replicate this result with inconsistent findings. Objective/Hypothesis This study aimed to reexamine effects of so-tDCS on declarative memory observed in young participants based on a previously described stimulation protocol used in elderly subjects. Methods 23 healthy participants (mean ± SD: 23.2 ± 1.9 years; 13 women) completed a word-pair test and a sequential finger tapping test before and after sleep. Participants received anodal so-tDCS bifrontaly at a frequency of 0.75 Hz or sham stimulation during NREM sleep N2, following a double-blind, placebo controlled, counterbalanced, randomized crossover design. Data were analyzed with respect to possible effects of stimulation on memory performances, sleep staging, spindle densities and EEG power in eight frequency bands. Results Stimulation had no significant effect on sleep dependent memory consolidation or on sleep macro- and microstructure. Independent of stimulation, procedural memory performances increased and declarative memory performances decreased overnight. This decline was less pronounced when participants had more than one learning opportunity. Fast parietal but not slow frontal spindle densities diminished from baseline to stimulation-free intervals under both stimulation conditions. Conclusion The present study could not reproduce the results of the seminal study in young subjects, but it is consistent with results observed in elderly subjects using the same protocol. Irrespective of stimulation, re-encoding opportunities in the word-pair test had an impact on memory strength and retrieval performance.

The results of studies on possible effects of radiofrequency electromagnetic fields (RF‐EMFs) on human waking electroencephalography (EEG) have been quite heterogeneous. In the majority of studies, changes in the alpha‐frequency range in subjects who were exposed to different signals of mobile phone‐related EMF sources were observed, whereas other studies did not report any effects. In this review, possible reasons for these inconsistencies are presented and recommendations for future waking EEG studies are made. The physiological basis of underlying brain activity, and the technical requirements and framework conditions for conducting and analyzing the human resting‐state EEG are discussed. Peer‐reviewed articles on possible effects of EMF on waking EEG were evaluated with regard to non‐exposure‐related confounding factors. Recommendations derived from international guidelines on the analysis and reporting of findings are proposed to achieve comparability in future studies. In total, 22 peer‐reviewed studies on possible RF‐EMF effects on human resting‐state EEG were analyzed. EEG power in the alpha frequency range was reported to be increased in 10, decreased in four, and not affected in eight studies. All reviewed studies differ in several ways in terms of the methodologies applied, which might contribute to different results and conclusions about the impact of EMF on human resting‐state EEG. A discussion of various study protocols and different outcome parameters prevents a scientifically sound statement on the impact of RF‐EMF on human brain activity in resting‐state EEG. Further studies which apply comparable, standardized study protocols are recommended. Bioelectromagnetics. 2019;40:291–318. © 2019 The Authors. Bioelectromagnetics Published by Wiley Periodicals, Inc.

Die Optimierung des Anpassungsprozesses des Abgasturboladers auf den Verbrennungsmotor wird zunehmend durch den Einsatz von eindimensionalen numerischen Simulationsmodellen unterstutzt. Um die Vorhersagegute der Motorprozesssimulation zu verbessern, mussen sowohl die Verbrennungsmodellierung als auch die Abgasturbolader–Simulationsmethodik optimiert werden. Hierzu wird in dieser Veroffentlichung ein Ansatz vorgestellt, welcher die Kombination einer datenbasierten Beschreibung des Hochdruck–Motorprozesses und des Emissionsverhaltens mit einer erweiterten physikalischen Ladungswechsel–Simulationsmethodik beinhaltet.

Studies have reported that exposure to radiofrequency electromagnetic fields (RF-EMF) emitted by mobile telephony might affect specific sleep features. Possible effects of RF-EMF emitted by Wi-Fi networks on sleep-dependent memory consolidation processes have not been investigated so far. The present study explored the impact of an all-night Wi-Fi (2.45 GHz) exposure on sleep-dependent memory consolidation and its associated physiological correlates. Thirty young males (mean �� standard deviation [SD]: 24.1 �� 2.9 years) participated in this double-blind, randomized, sham-controlled crossover study. Participants spent five nights in the laboratory. The first night was an adaptation/screening night. The second and fourth nights were baseline nights, each followed consecutively by an experimental night with either Wi-Fi (maximum: psSAR10g =

Background Although there are several human experimental studies on short-term effects of radiofrequency electromagnetic fields (RF-EMF) on sleep, the role of effect modification by sex or age in this context has not yet been considered. In an earlier study, we observed sex differences in RF-EMF effects in elderly subjects. The present study investigated possible RF-EMF effect modifications by age in men. Methods Data available for the present analysis come from three double-blind, randomized cross-over studies, in which effects of different RF-EMF exposure signals on sleep were investigated in young [sample 1: 25.3 (mean) ± 2.6 (SD) years; sample 2: 25.4 ± 2.6 years; n = 30, respectively] and older (69.1 ± 5.5 years; n = 30) healthy male volunteers. Studies comprised a screening/adaptation night followed by nine experimental nights at two-week intervals. RF-EMF exposure effect modifications by age were analysed for two different exposure signals (GSM900 at 2 W/kg, TETRA at 6 W/kg), each compared to a sham exposure. Polysomnography, during which the exposure signals were delivered by a head worn antenna, as well as sleep staging were performed according to the AASM standard. Four subjective and 30 objective sleep parameters were statistically analysed related to possible RF-EMF effects. Results Comparisons of sleep parameters observed under sham exposure revealed highly pronounced physiological differences between young and elderly men. A consistent exposure effect in both age groups was found for a shorter latency to persistent sleep under TETRA exposure reflecting a sleep-promoting effect. Exposure effect modifications by age were observed for two of the four self-reported sleep parameters following GSM900 exposure and for arousals during REM sleep under TETRA exposure. Conclusions As effects of a short-term all-night RF-EMF exposure on sleep occurred only sporadically in young and elderly men, it seems that age doesn't matter in this respect. However, as long as there are no corresponding data from young healthy women that would allow a comparison with the data from elderly women, this assumption cannot be conclusively verified. Nevertheless, the present results are not indicative of any adverse health effects.

The recording of slow pupillary oscillations in complete darkness is a promising approach for objective evaluation of daytime sleepiness at the physiological level. The aim of the present study was to analyze the magnitude of between- and within-subject variation of the pupillary unrest index (PUI) in a sample of healthy individuals. The present data were collected within the framework of a mobile phone study on possible effects of radiofrequency electromagnetic fields (RF-EMF) on the central nervous system. Pupillary behavior was monitored in 30 young healthy male volunteers (age 18–30 years) on ten non-consecutive experimental days at 11:00 a.m. and 04:00 p.m., using infrared video pupillography (compact integrated pupillograph, CIP). Since RF-EMF had no impact on the PUI, data were pooled for the present analysis. Mixed-model analyses of variance (ANOVAs) showed that the PUI was subject to higher interindividual variation as compared to intraindividual variation at both times of measurement. This resulted in intraclass correlation coefficients pointing to a substantial stability of these interindividual differences. A comparison of the PUI results with currently used cutoff values revealed that more than 50% of recordings from young, healthy, non-sleep-disturbed males showed values beyond the “normal” range. The significant interindividual variability implies that the PUI is not only a state marker. Evaluations of such measurements should therefore consider the PUI as a possible trait marker to ensure comparability and correct interpretation.

Background Results from human experimental studies investigating possible effects of radiofrequency electromagnetic fields (RF-EMF) on sleep are heterogeneous. So far, there is no study on possible sex-differences in RF-EMF effects. Objectives The present study aimed at analyzing differences in RF-EMF effects on the macrostructure of sleep between healthy elderly males and females. Methods With a double-blind, randomized, sham-controlled cross-over design effects of two RF-EMF exposures (GSM900 and TETRA) on sleep were investigated in samples of 30 elderly healthy male and 30 healthy elderly female volunteers. Participants underwent each of the three exposure conditions on three occassions following an individually randomized order resulting in a total of nine study nights per participant. Exposure was delivered for 30 min prior to sleep and for the whole night (7.5 h) by a head worn antenna specifically designed for the projects. The peak spatial absorption rate averaged over time in head tissues (psSAR10g) was 6 W/kg for TETRA and 2 W/kg for GSM900. Thirty variables characterising the macrostructure of sleep and arousals as well as four subjective sleep variables were considered for statistical analyses. Results Multivariate analyses revealed that exposure to GSM900 and/or TETRA resulted in a significant reduction in arousals, a shorter latency to sleep stage N3, and a shorter self-reported time awake after sleep in both males and females. Exposure effects depending on sex (significant interactions) were observed. Latency to sleep stage R was shorter in females and tended to be longer in males under both exposures. Latency to stage N3 was shorter in females under TETRA exposure and almost not affected in males. The time awake within the sleep period under TETRA exposure was shorter in females and only slightly longer in males. Under GSM exposure, the self-rated total sleep time tended to be longer in females and to be shorter in males. Finally, the number of awakenings was lower only in females and tended to be higher in males under GSM exposure. Discussion With regard to RF-EMF effects on human sleep it seems that gender matters since GSM900 and TETRA led to significantly more exposure effects in females. Regardless of gender, none of the observed changes is indicative of a sleep disturbing effect of RF-EMF exposure. Observed effects might be mediated by skin related thermoregulatory mechanisms.

A new head exposure system for double-blind provocation studies investigating possible effects of 2.45 GHz Wi-Fi exposure on human sleep was developed and dosimetrically analyzed. The exposure system includes six simultaneously radiating directional antennas arranged along a circle (radius 0.6 m) around the test subject's head, and enables a virtually uniform head exposure, i.e. without any preferred direction of incidence, during sleep. The system is fully computer-controlled and applies a real wireless local area network (WLAN) signal representing different transmission patterns as expected in real WLAN scenarios, i.e. phases of "beacon only" as well as phases of different data transmission rates. Sham and verum are applied in a double-blind crossover study design and all relevant exposure data, i.e. forward and reverse power at all six antenna inputs, are continuously recorded for quality control. For a total antenna input power (sum of all antennas) of 220 mW, typical specific absorption rate (SAR) in cortical brain regions is approximately 1-2 mW/kg (mass average SAR over respective brain region), which can be seen as a realistic worst-case exposure level in real WLAN scenarios. Taking into account variations of head positions during the experiments, the resulting exposure of different brain regions may deviate from the given average SAR levels up to 10 dB. Peak spatial 10 g average SAR in all brain and all head tissues is between 1.5-3.5 and 10.4-25 mW/kg, respectively. Bioelectromagnetics. © 2020 Bioelectromagnetics Society.

Background The use of wireless telecommunication systems such as wireless fidelity (Wi-Fi)-enabled devices has steadily increased in recent years. There are persistent concerns that radiofrequency electromagnetic field (RF-EMF) exposure might affect health. Possible effects of RF-EMF exposure on human sleep were examined with regard to mobile phones and base stations, but not with regard to Wi-Fi exposure. Objectives The present double-blind, sham-controlled, randomized, fully counterbalanced cross-over study addressed for the first time the question whether a whole night Wi-Fi exposure has an effect on sleep. Methods Thirty-four healthy young male subjects (mean ± SD: 24.1 ± 2.9 years) spent five nights in the sleep laboratory. A screening and adaptation night was followed by two experimental nights. Each of the experimental nights was preceded by a baseline night. Sleep was evaluated at the subjective level by a questionnaire and at the objective level (macro- and microstructure) by polysomnography. Either 2.45 GHz Wi-Fi (max psSAR10g of 6.4 mW/kg) or sham signals were delivered by a newly developed head exposure facility. Results Results showed no statistically significant acute effects of a whole-night Wi-Fi exposure on subjective sleep parameters as well as on parameters characterizing the macrostructure of sleep. Analyses of the microstructure of sleep revealed a reduction in global EEG power in the alpha frequency band (8.00–11.75 Hz) during NREM sleep under acute Wi-Fi exposure compared to sham. Discussion The results of the present human experimental study are well in line with several other neurophysiological studies showing that acute RF-EMF exposure has no effect on the macrostructure of sleep. The slight physiological changes in EEG power observed under Wi-Fi exposure are neither reflected in the subjective assessment of sleep nor at the level of objective measurements. The present results are not indicative of a sleep disturbing effect of Wi-Fi exposure.

Background Studies on effects of radio frequency-electromagnetic fields (RF-EMF) on the macrostructure of sleep so far yielded inconsistent results. This study investigated whether possible effects of RF-EMF exposure differ between individuals. Objective In a double-blind, randomized, sham-controlled cross-over study possible effects of electromagnetic fields emitted by pulsed Global System for Mobile Communications (GSM) 900 and Wideband Code-Division Multiple Access (WCDMA)/Universal Mobile Telecommunications System (WCDMA/UMTS) devices on sleep were analysed. Methods Thirty healthy young men (range 18–30 years) were exposed three times per exposure condition while their sleep was recorded. Sleep was evaluated according to the American Academy of Sleep Medicine standard and eight basic sleep variables were considered. Results Data analyses at the individual level indicate that RF-EMF effects are observed in 90% of the individuals and that all sleep variables are affected in at least four subjects. While sleep of participants was affected in various numbers, combinations of sleep variables and in different directions, showing improvements but also deteriorations, the only consistent finding was an increase of stage R sleep under GSM 900 MHz exposure (9 of 30 subjects) as well as under WCDMA/UMTS exposure (10 of 30 subjects). Conclusions The results underline that sleep of individuals can be affected differently. The observations found here may indicate an underlying thermal mechanism of RF-EMF on human REM sleep. Nevertheless, the effect of an increase in stage R sleep in one third of the individuals does not necessarily indicate a disturbance of sleep.

The purpose of the present analysis was to quantify the magnitude of intersubject and intrasubject variation of sleep spindle characteristics in a sample of healthy young males. A total of 32 volunteers (age range 20–30 years) participated in a crossover study aimed at investigating possible effects of Terrestrial Trunked Radio (TETRA) signals on cognitive performance and human brain activity during sleep and waking. Sleep was polysomnographically assessed on nine identically organized study nights per individual. The inter- and intraindividual variability of automatically detected stage 2 non-rapid eye movement (NREM) sleep spindle (11–16 Hz) characteristics (number, density, duration, frequency, amplitude) derived from C3-A2 was determined. Stability of individual differences and the underlying variations were quantified using intraclass correlation (ICC) and coefficients of variation (CV), respectively. Note that there was no significant exposure effect on the considered sleep spindle characteristics. All sleep spindle variables showed an ICC coefficient higher than 0.8, indicating almost perfect stability of interindividual differences. Interindividual variability differed strongly between the considered spindle parameters (CV range: 2–53 %). Intraindividual variability was for all parameters less pronounced (mean CV range: 1–24 %), but their ratios underline the high degree of individuality of each of the investigated parameters. The present analysis confirms the strong individual night-to-night stability of sleep spindle characteristics reported by previous studies. The results provide further evidence for treating sleep spindles as a possible trait, an issue which should be considered in studies relying on a parallel-group design. These data can also be used as reference values.

An experimental investigation of warming and warmth perception caused by handset EMF exposure was performed in order to examine its possible impact on blinding. Healthy male participants (15) were exposed to three different exposure conditions: sham and Terrestrial Trunked Radio (TETRA) handsets with maximum 10 g averaged SAR values of 1.5 and 6 W/kg each on three days. The study followed a randomized, double-blind design. TETRA signals simulated exposure from a handheld device consisting of a 385 MHz carrier modulated with a pulse length of 14.17 ms and a pulse period of 56.67 ms (i.e., duty cycle 25%; 17.65 Hz pulse modulation). A body worn antenna was used and fixed at the left ear. In addition to subjective ratings, skin temperatures at two locations close to the radiating element of the body-worn antenna were measured. The measurements revealed a temperature rise proportional to the supplied RF power with an average temperature increase measured at the two locations of 0.8 °C following the high exposure level of 6 W/kg. However, subjects were not able to distinguish between exposure conditions based on their subjective perception and thus the double-blinding was ensured. Bioelectromagnetics. 35:452–458, 2014. © 2014 Wiley Periodicals, Inc.

Background Studies have shown that exposure to radiofrequency electromagnetic fields (RF-EMF) in the mobile communication frequency range may induce physiological modifications of both spontaneous as well as event-related human electroencephalogram. So far, there are very few peer-reviewed studies on effects of Terrestrial Trunked Radio (TETRA), which is a digital radio communication standard used by security authorities and organizations in several European countries, on the central nervous system. Objectives To analyze the impact of simulated TETRA handset signals at 385 MHz on slow cortical potentials (SCPs). Methods 30 young healthy males (25.2±2.7 years) were exposed in a double-blind, counterbalanced, cross-over design to one of three exposure levels (TETRA with 10 g averaged peak spatial SAR: 1.5 W/kg, 6.0 W/kg and sham). Exposure was conducted with a body worn antenna (especially designed for this study), positioned at the left side of the head. Subjects had 9 test sessions (three per exposure condition) in which three SCPs were assessed: SCP related to a clock monitoring task (CMT), Contingent negative variation (CNV) and Bereitschaftspotential (BP). Results Neither behavioral measures nor the electrophysiological activity was significantly affected by exposure in the three investigated SCP paradigms. Independent of exposure, significant amplitude differences between scalp regions could be observed for the CMT-related SCP and for the CNV. Conclusions The present results reveal no evidence of RF-EMF exposure-dependent brain activity modifications investigated at the behavioral and the physiological level.

Optical pyrometers provide many advantages over intrusive measuring techniques in determining the spatial and time varying temperature distribution of fast rotating components in gas turbines. This paper describes the development and evaluation of a versatile high-resolution pyrometer system and its application to radial turbine rotor temperature mapping as has been done in a R&D project at the Technical University Berlin under funding from Siemens Power Generation (KWU). The development goal was a pyrometer system with a temporal resolution of 1 μs, a minimum field of view of 1 mm, and a measurement range from 600 to 1500°C. A prototype of the pyrometer system has been built and tested at the small gas turbine test facility of the Technical University Berlin. The system yielded excellent results with respect to measurement uncertainty, resolution, and reliability. Finally, measurement results obtained with the new system on a radial turbine rotor and on a heavy duty industrial gas turbine are compared with measurements conducted with a commercially available turbine pyrometer system.

Transcranial direct current stimulation (tDCS) is a method to stimulate the brain in a noninvasive manner leading either to an increased (anodal stimulation) or a decreased (cathodal stimulation) excitability of cortical neurons. Slow oscillations with a frequency below 1 Hz are assumed to be associated with sleep-dependent consolidation of declarative memories by exerting a temporal synchronizing influence on hippocampal reactivations and thalamic spindle activity. Many studies have revealed that offline consolidation during sleep varies with age showing better performances in the young compared to the elderly. A study in young subjects provided evidence of a beneficial impact of an anodal slow oscillation tDCS (0.75 Hz) during early SWS-rich on declarative memory but not on procedural memory. These results could not be confirmed in a study on elderly subjects (Eggert et al., 2013). The present study aims to replicate the results, which have been observed in younger subjects (Marshal et al., 2006). To be able to test an effect of 0.65 with a power of 0.8 and a double-sided alpha 2 ) is triggered after the first 8 consecutive epochs of NREM sleep 2 immediately before the first occurrence of slow wave sleep. The total 25 ′ 8 ″ stimulation period is divided into five 5 ′ 16 ″ intervals, each of them followed by 1 min break without stimulation. To test for a stimulation-dependent effect on offline consolidation during sleep a declarative memory task (word pair test) and a procedural memory task (finger-tapping) have to be completed before sleep and after awakening. Furthermore, sleep stages were scored and EEG power and spindle densities were computed. Statistical analysis was based upon comparisons between the tDCS and the sham stimulation condition. Currently 18 subjects (10 males and 8 females) are already enrolled. First results will be presented at the meeting.

Background TETRA (terrestrial trunked radio) is a digital radio communication standard, which has been implemented in several European countries and is used by public executives, transportation services, and by private companies. Studies on possible impacts on the users' health considering different exposure conditions are missing. Objectives To investigate possible acute effects of electromagnetic fields (EMF) of two different levels of TETRA hand-held transmitter signals on cognitive function and well-being in healthy young males. Methods In the present double-blind cross-over study possible effects of short-term (2.5 h) EMF exposure of handset-like signals of TETRA (385 MHz) were studied in 30 healthy male participants (mean±SD: 25.4±2.6 years). Individuals were tested on nine study days, on which they were exposed to three different exposure conditions (Sham, TETRA 1.5 W/kg and TETRA 6.0 W/kg) in a randomly assigned and balanced order. Participants were tested in the afternoon at a fixed timeframe. Results Attention remained unchanged in two out of three tasks. In the working memory significant changes were observed in two out of four subtasks. Significant results were found in 5 out of 35 tested parameters, four of them led to an improvement in performance. Mood, well-being and subjective somatic complaints were not affected by TETRA exposure. Conclusions The results of the present study do not indicate a negative impact of a short-term EMF-effect of TETRA on cognitive function and well-being in healthy young men.

An experimental investigation of warming and warmth perception caused by handset EMF exposure was performed in order to examine its possible impact on blinding. Healthy male participants (15) were exposed to three different exposure conditions: sham and Terrestrial Trunked Radio (TETRA) handsets with maximum 10 g averaged SAR values of 1.5 and 6 W/kg each on three days. The study followed a randomized, double-blind design. TETRA signals simulated exposure from a handheld device consisting of a 385 MHz carrier modulated with a pulse length of 14.17 ms and a pulse period of 56.67 ms (i.e., duty cycle 25%; 17.65 Hz pulse modulation). A body worn antenna was used and fixed at the left ear. In addition to subjective ratings, skin temperatures at two locations close to the radiating element of the body-worn antenna were measured. The measurements revealed a temperature rise proportional to the supplied RF power with an average temperature increase measured at the two locations of 0.8 °C following the high exposure level of 6 W/kg. However, subjects were not able to distinguish between exposure conditions based on their subjective perception and thus the double-blinding was ensured.

The state of California assumed a pioneering role in efforts to restrict toxic emissions emanating from motor vehicles. This development arises from the fact that the geography of large cities like Los Angeles prevents wind from dispersing exhaust gases, causing a blanket of fog that smothers the city. The resulting smog not only has damaging impacts on the health of city dwellers, but also impairs visibility severely.

Background: Studies in young healthy volunteers provided evidence of a beneficial impact of an anodal time-varied transcranial direct current stimulation (tDCS) during early slow wave rich sleep on declarative memory but not on procedural memory. Objective/hypothesis: The present study investigated whether sleep-dependent memory consolidation can also be affected by slow oscillating tDCS in a population of elderly subjects. Methods: 26 subjects (69.1 years ± 7.7 years) received bi-frontal anodal stimulation (max. current density: 0.331 mA/cm2) during early NREM sleep in a double-blind placebo-controlled randomized crossover study. Stimulation effects on offline consolidation were tested by using a declarative and a procedural memory task. Furthermore, sleep stages were scored, EEG power was analyzed and spindle densities were assessed. Results: Independently from stimulation condition, performance in both memory tasks significantly decreased overnight. Stimulation revealed no significant effect on sleep-dependent memory consolidation. Verum tDCS was accompanied by significantly more time awake and significantly less NREM stage 3 sleep during five 1-min stimulation free intervals. Conclusions: The results of the present study are in line with other studies showing that offline consolidation during sleep varies with age and is less pronounced in the elderly than in young or middle-aged subjects. Contrary to an almost identical positive study in young adults, slow oscillatory tDCS applied to the elderly failed to show a beneficial effect on memory consolidation in the present study.

Objectives: The Pupillographic Sleepiness Test (PST) measures the level of alertness based on spontaneous oscillations in pupillary size. Reference data are available for male and female adults within the age range 20–60 years. The aim of the present multicenter study was to extend the age range for reference data from 20 to 79 years. Methods: A total of 239 healthy subjects, selected from three different centers (Berlin, Regensburg, and Vienna), were administered the PST. Data were analyzed with respect to possible effects of age, gender, and time of day on the pupillary unrest index (PUI) and the pupil diameter (PD). Results: Reliable data were available in 85.8% of the entire study sample and in 82.4% of elderly subjects (60+ years). Age-related changes were identified for the PUI and PD. There was no effect of gender on pupillometric variables as revealed by univariate analysis. The PD was found to be smaller in the afternoon compared with the morning. However, if subjects aged 60+ years were excluded from the analyses, the age-related changes disappeared and a time-of-day effect regarding the PUI became apparent. Conclusions: PUI and PD were found to decrease with increasing age. In addition, the present data show that nonreliable PST data occur more frequently in the elderly probably because of dry eyes, inadequate testing conditions, and technical resolution limitations. Thus, the PST results obtained here from elderly subjects are limited and have to be interpreted with caution. Additional research on elderly specific assessment tools is needed. Am. J. Hum. Biol. 2012. © 2012Wiley Periodicals, Inc.

A new head exposure system for double-blind provocation studies investigating possible effects of terrestrial trunked radio (TETRA)-like exposure (385 MHz) on central nervous processes was developed and dosimetrically analyzed. The exposure system allows localized exposure in the temporal brain, similar to the case of operating a TETRA handset at the ear. The system and antenna concept enables exposure during wake and sleep states while an electroencephalogram (EEG) is recorded. The dosimetric assessment and uncertainty analysis yield high efficiency of 14 W/kg per Watt of accepted antenna input power due to an optimized antenna directly worn on the subject's head. Beside sham exposure, high and low exposure at 6 and 1.5 W/kg (in terms of maxSAR10g in the head) were implemented. Double-blind control and monitoring of exposure is enabled by easy-to-use control software. Exposure uncertainty was rigorously evaluated using finite-difference time-domain (FDTD)-based computations, taking into account anatomical differences of the head, the physiological range of the dielectric tissue properties including effects of sweating on the antenna, possible influences of the EEG electrodes and cables, variations in antenna input reflection coefficients, and effects on the specific absorption rate (SAR) distribution due to unavoidable small variations in the antenna position. This analysis yielded a reasonable uncertainty of

Optical pyrometers provide many advantages over intrusive measuring techniques in determining the spatial and time varying temperature distribution of fast rotating components in gas turbines. This paper describes the development and evaluation of a versatile high resolution pyrometer system and its application to radial turbine rotor temperature mapping as has been done in a R&D project at the Technical University Berlin under funding from Siemens Power Generation (KWU). The development goal was a pyrometer system with a temporal resolution of 1μs, a minimum field of view of 1 mm, and a measurement range from 600 to 1500°C. A prototype of the pyrometer system has been built and tested at the small gas turbine test facility of the Technical University Berlin. The system yielded excellent results with respect to measurement uncertainty, resolution, and reliability. Finally, measurement results obtained with the new system on a radial turbine rotor and on a heavy duty industrial gas turbine are compared with measurements conducted with a commercially available turbine pyrometer system.

The paper describes a test facility for small-scale gas turbines, which basically has been designed and assembled at the Institute of Combustion Engines of the Technical University Berlin. The facility exposes ceramic rotor components to the most significant loads that occur during real gas turbine operation in a clearly predefined manner (high circumferential velocities and highest turbine inlet temperatures). The test facility allows the investigation of bladed radial inflow turbine rotors, as well as — in a preceding step — geometrically simplified ceramic or coated metallic rotors. A newly designed, ceramically lined, variable geometry combustion chamber allows turbine inlet temperatures up to 1450°C (2640 F). A fast thermal shock unit (switching time of about 1s), which is integrated into the test facility between the combustion chamber and the turbine scroll, can be used to create, for example, severe transient temperature gradients within the rotor components to simulate gas turbine trip conditions. In order to generate steady state temperature gradients, especially during disk testing, the rotor components can be subjected to an impingement cooling of the rotor back face (uncoated in case of TBC-testing). The test facility is additionally equipped with a non-contact transient temperature measurement system (turbine radiation pyrometry) to determine the test rotor surface temperature distribution during operation. Apart from the possibilities of basic rotor material investigations, the test facility can also be used to automatically generate compressor and turbine performance characteristics maps. The latter might be used to assess the aerodynamic performance of bladed ceramic radial inflow or mixed flow turbine rotors with respect to manufacturing tolerances due to near-net-shape forming processes (e.g., gelcasting or injection molding).Copyright © 1998 by ASME