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Coastal seas are under increasing pressure from extreme weather events and sea level rise, resulting in impacts such as changing hydrodynamic conditions, coastal erosion, and marine heat waves. To monitor changes in coastal marine habitats, such as reefs and macrophytes meadows, which add to the resilience of our coasts, consistent, medium- to long-term seafloor observations are needed. This project aims to deliver repeated, high-frequency sonar surveys on a stationary seabed mooring of a specific target area over a period of up to several months. A new stand-alone subsea system, the Sonarlogger, based on a battery pack, low-power logger and a high-resolution scanning sonar, was developed. It allows for long-term deployments with a customisable battery pack, WI-FI download and configurable sleep state. The system has been tested for over 130 days in dynamic coastal environments off the Belgian coast. Combined with auxiliary sensors, such as for measuring currents, waves and turbidity, this system enables comprehensive studies of morphologic changes and changing benthic ecosystems. Moreover, this system has the capacity to provide measurements of coastal environments during storms, where conventional systems may fall short, providing insights into event-based changes of the seafloor.

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Exposure to ultrafine particles has a significant influence on human health. In regions with large commercial airports, air traffic and ground operations can represent a potential particle source. The particle number concentration was measured in a low-traffic residential area about 7 km from Frankfurt Airport with a Condensation Particle Counter in a long-term study. In addition, the particle number size distribution was determined using a Fast Mobility Particle Sizer. The particle number concentrations showed high variations over the entire measuring period and even within a single day. A maximum 24 h-mean of 24,120 cm-3 was detected. Very high particle number concentrations were in particular measured when the wind came from the direction of the airport. In this case, the particle number size distribution showed a maximum in the particle size range between 5 and 15 nm. Particles produced by combustion in jet engines typically have this size range and a high potential to be deposited in the alveoli. During a period with high air traffic volume, significantly higher particle number concentrations could be measured than during a period with low air traffic volume, as in the COVID-19 pandemic. A large commercial airport thus has the potential to lead to a high particle number concentration even in a distant residential area. Due to the high particle number concentrations, the critical particle size, and strong concentration fluctuations, long-term measurements are essential for a realistic exposure analysis.

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Plasma-enhanced atomic layer deposition (PEALD) is utilized to improve the barrier properties of an organic chip-film patch (CFP) when it is used as an implant to prevent moisture and ions from migrating into the embedded electronic circuits. For this purpose, surface condition and material properties of eight modifications of Al2O3-TiO2 nanolaminates sequentially deposited on polyimide PI-2611 films are evaluated in detail. The effect of stress-induced warpage of the deposited Al2O3-TiO2 on the wafer level is calculated with the Stoney equation and reveals higher tensile stress values while increasing the thickness of Al2O3-TiO2 nanolaminates from 20 up to 80 nm. Contact angle measurement and atomic force microscopy are used to investigate the surface energy and wettability, as well as the surface morphology of polyimide-Al2O3-TiO2 interfaces. We show that plasma treatment of pristine polyimide leads to an enhanced adhesion force of the PEAL-deposited layer by a factor of 1.3. The water vapor transmission rate (WVTR) is determined by exposing the coated polyimide films to 85% humidity and 23 °C and yields down to 1.58 × 10-3 g(H2O)/(m2 d). The data obtained are compared with alternative coating processes using the polymers parylene-C and benzocyclobutene (BCB). The latter shows higher WVTR values of 1.2 × 10-1 and 1.7 × 10-1 g(H2O)/(m2 d) compared to the PEALD-PI-2611 systems, indicating lower barrier properties. Two Al2O3-TiO2 modifications with low WVTR values have been chosen for encapsulating the CFP substrates and exposing them in a long-time experiment to chemical and mechanical loads in a chamber filled with phosphate-buffered saline at 37 °C, pH 7.3, and a cyclically applied pressure of 160 mbar (∼120 mm Hg). The electrical leakage behavior of the CFP systems is measured and reveals reliable electrical long-term stability far beyond 11 months, highlighting the great potential of PEALD-encapsulated CFPs.

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The measurement of the CO2 concentration has a wide range of applications. Traditionally, it has been used to assess air quality, with other applications linked to the experimental assessment of occupancy patterns and air renewal rates. More recently, the worldwide dissemination of COVID-19 establishing a relationship between infection risk and the mean CO2 level has abruptly led to the measurement of the CO2 concentration in order to limit the spread of this respiratory disease in the indoor environment. Therefore, the extensive application of this measurement outside of traditional air quality assessment requires an in-depth analysis of the suitability of these sensors for such modern applications. This paper discusses the performance of an array of commercial wall-mounted CO2 sensors, focusing on their application to obtain occupancy patterns and air renovation rates. This study is supported by several long-term test campaigns conducted in an in-use office building located in south-eastern Spain. The results show a spread of 19-101 ppm, with a drift of 28 ppm over 5 years, an offset of 2-301 ppm and fluctuations up to 80 ppm in instantaneous measurements not related to concentration changes. It is proposed that values averaged over 30 min, using a suitable reference value, be used to avoid erroneous results when calibration is not feasible.

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The rapid growth of the wireless communication industry has resulted in the installation of numerous of base stations, everywhere in our surroundings. The population is exposed to Radio Frequency Electromagnetic Fields of varying frequency and strength. This, and introduction of new systems have risen public concerns regarding potential health effects from this RF-EMF exposure. The purpose of this project is to get an overview of any changes in exposure when new technologies are introduced. From June 2013 to October 2019, measurements were made at 16 measurement points in Kristiansand and surrounding areas in the same order, on the same day of the week and at the same time of day. The measurements are performed on the frequency bands 390, 450, 800, 900, 1800, 2100, 2400, and 2600 MHz. When we summed up the exposure for all the frequency bands relative to the limit values in a measuring point, the total values per measuring point showed that the exposure outdoors in most cases is less than 1‰ of the limit value. In 2017, a temporary increase was registered for most measurement points, but during 2018 the levels returned to the levels registered before 2017. During the increase, the levels were still low, around 3‰ of the limit values. The increase may be due to the fact that two mobile operators during this period made a comprehensive reconfiguration of their networks. The measurements presented in this report show that the exposure of the population is low, thousandths of the limit values, and relatively constant over time even though new technologies are introduced.

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The effect of road traffic noise in urban environments is an issue of social and scientific interest, due to its public health and economic impacts. Scientific literature showed a decrease in the level of tyre/road noise generated as temperature increases, but usually under standardised traffic conditions in non-urban environments. Based on a wide network for the hourly monitoring of road traffic flow, air temperature and noise levels across the city of Madrid (Spain), this work proposes and applies a new experimental methodology for studying the dependence of urban road traffic noise on temperature. This study was conducted under real-world traffic conditions involving a wide variability in urban configurations and in the type and state of preservation of vehicles, tires and pavements. From the analysis of data for a whole year, a time interval was identified (from Tuesday to Thursday and between 8 a.m. and 8 p.m.) in which the variability in road traffic flow for the whole city of Madrid was stable enough to allow for a linear regression study between temperature and noise levels from urban road traffic. The relationships found were highly significant (p ≤ 0.001) for data from all the noise monitoring stations, with values of higher than 20% and up to 42% for the explanation of the variability in the measured noise levels by temperature at most of the measurement points. The values of the slope coefficients at the noise monitoring stations ranged from -0.036 to -0.125 dB/°C, with an average value of -0.090 ± 0.011 dB/°C. These results are within the range of values reported in the scientific literature for experimental tests conducted under conditions of controlled or free-flowing traffic.

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Objective.Microstimulation via electrodes that penetrate the visual cortex creates visual perceptions called phosphenes. Besides providing electrical stimulation to induce perceptions, each electrode can be used to record the brain signals from the cortex region under the electrode which contains brain state information. Since the future visual prosthesis interfaces will be implanted chronically in the visual cortex of blind people, it is important to study the long-term stability of the signals acquired from the electrodes. Here, we studied the changes over time and the repercussions of electrical stimulation on the brain signals acquired with an intracortical 96-channel microelectrode array implanted in the visual cortex of a blind volunteer for 6 months.Approach.We used variance, power spectral density, correlation, coherence, and phase coherence to study the brain signals acquired in resting condition before and after the administration of electrical stimulation during a period of 6 months.Main results.Variance and power spectral density up to 750 Hz do not show any significant trend in the 6 months, but correlation coherence and phase coherence significantly decrease over the implantation time and increase after electrical stimulation.Significance.The stability of variance and power spectral density in time is important for long-term clinical applications based on the intracortical signals collected by the electrodes. The decreasing trends of correlation, coherence, and phase coherence might be related to plasticity changes in the visual cortex due to electrical microstimulation.

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Most of market-available logic analyzers are designed for hardware debug purposes and cannot record continuous measurement in long-term while in different fields of scientific research it is necessary to make data acquisition within small periods (less then 1 ms) during several hours or even days. The common example is real-time communication worst-case jitter analysis. This paper introduces an easy to implement approach how to create a logic analyzer for such kind of task on a basis of a low-cost Field-Programmable Gate Array (FPGA) kit and a personal computer. The Author provides both sample FPGA design files compatible with an open-source toolchain and the approach how to collect data using standard software and Octave scripts to post-process the experimental result. Following the Author's guidelines even with minimal knowledge in FPGA design makes it easy to modify the introduced hardware for specific laboratory team needs.

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Tree autotrophic respiratory processes, especially stem respiration or stem CO2 efflux (Estem), are important components of the forest carbon budget. Despite efforts to investigate the controlling processes of Estem in recent years, a considerable lack in our knowledge remains on the abiotic and biotic drivers affecting Estem dynamics. It has been strongly advocated that long-term measurements would shed light onto those processes. The expensive scientific instruments needed to measure gas exchange have prevented Estem measurements from being applied on a larger temporal and spatial scale. Here, we present an automated closed dynamic chamber system based on inexpensive and industrially broadly applied CO2 sensors, reducing the costs for the sensing system to a minimum. The CO2 sensor was cross-calibrated with a commonly used gas exchange system in the laboratory and in the field, and we found very good accordance of these sensors. We tested the system under harsh tropical climatic conditions, characterized by heavy tropical rainfall events, extreme humidity and temperatures, in a moist lowland forest in Malaysia. We recorded Estem of three Dyera costulata (Miq.) trees with our prototype over various days. The variation of Estem was large among the three tree individuals and varied by 7.5-fold. However, clear diurnal changes in Estem were present in all three tree individuals. One tree showed high diurnal variation in Estem, and the relationship between Estem and temperature was characterized by a strong hysteresis. The large variations found within one single tree species highlight the importance of continuous measurement to quantify ecosystem carbon fluxes.

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The ventilation modalities in most Chinese residences are infiltration and opening windows. We measured infiltration rates and air change rates at night, with no attempt to change occupants' behaviors, of urban residences in five climate zones of China during four seasons. Using the CO2 decay method, we found the median infiltration rate for 294 residences to be 0.34 h-1 . Using occupant-generated CO2 as tracer gas, we determined air change rates over the course of 1 year in 46 bedrooms at night from mass balance considerations. In 54% of the measurements, windows were closed, so ventilation was only by infiltration. Windows were mainly closed when the outdoor temperature was below 15°C and above 26°C. The median infiltration rates did not differ appreciably among seasons and climate zones and were always less than 0.45 h-1 .

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The results presented in this work demonstrate for the first time a distribution of elements in the spectral analysis of aerosols in the suburban continental Balkan Peninsula. Samples were collected in the suburban area of Belgrade (Serbia) in the period from March 2012 till December 2013. Results presented here are from long-term measurements of masses of size-segregated aerosols and macro- and microelements in the range of PM0.27-16. The following elements were analyzed: Al, Ag, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Sb, Ti, Tl, V, and Zn; levels of Be, Hg, and Se were under the detection limits in all samples. Average concentrations and time and seasonal variations of particulate matter (PM) as well as element contents and their percentage shares are given. The results showed the domination of particle content around the accumulation mode in the range of 0.53 < Dp < 1.06 µm, but the fractional distribution of elements showed maximal average concentrations in different fractions depending on the origin of each element. Crustal elements (Al, Ca, Fe, Mg, Mn, Ti, etc.) dominated in coarse mode, while anthropogenic elements (As, Cd, Cu, Pb, Sb, etc.) were mainly distributed in fine mode fractions. Some elements, such are As and Ni, were detected in investigated aerosols only occasionally, while others, such as Ca, Fe, and Mg, were detected in all analyzed samples. The application of multivariate analysis (PCA) demonstrated the connection between the elements of similar origin, in fine fractions mainly of anthropogenic origin, while in coarse mode of crustal origin, indicating the resuspension with contribution of about 40%. The contents of some measured elements were compared with their contents in aerosols in some European suburban areas.

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The cerebral autoregulatory state as well as fluctuations in arterial (SpO2) and cerebral tissue oxygen saturation (StO2) are potentially new relevant clinical parameters in preterm neonates. The aim of the present study was to test the investigative capabilities of data analysis techniques for nonlinear dynamical systems, looking at fluctuations and their interdependence. StO2, SpO2 and the heart rate (HR) were measured on four preterm neonates for several hours. The fractional tissue oxygenation extraction (FTOE) was calculated. To characterize the fluctuations in StO2, SpO2, FTOE and HR, two methods were employed: (1) phase-space modeling and application of the recurrence quantification analysis (RQA), and (2) maximum entropy spectral analysis (MESA). The correlation between StO2 and SpO2 as well as FTOE and HR was quantified by (1) nonparametric nonlinear regression based on the alternating conditional expectation (ACE) algorithm, and (2) the maximal information-based nonparametric exploration (MINE) technique. We found that (1) each neonate showed individual characteristics, (2) a ~60 min oscillation was observed in all of the signals, (3) the nonlinear correlation strength between StO2 and SpO2 as well as FTOE and HR was specific for each neonate and showed a high value for a neonate with a reduced health status, possibly indicating an impaired cerebral autoregulation. In conclusion, our data analysis framework enabled novel insights into the characteristics of hemodynamic and oxygenation changes in preterm infants. To the best of our knowledge, this is the first application of RQA, MESA, ACE and MINE to human StO2 data measured with near-infrared spectroscopy (NIRS).

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Currently, the need for mobility can cause significant pollution levels in cities, with important effects on health and quality of life. Any approach to the study of urban pollution and its effects requires an analysis of spatial distribution and temporal variability. It is a crucial dilemma to obtain proven methodologies that allow an increase in the quality of the prediction and the saving of resources in the spatial and temporal sampling. This work proposes a new analytical methodology in the study of temporal structure. As a result, a model for estimating annual levels of urban traffic noise was proposed. The average errors are less than one decibel in all acoustics indicators. A new working methodology of urban noise has begun. Additionally, a general application can be found for the study of the impacts of pollution associated with traffic, with implications for urban design and possibly in economic and sociological aspects.

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