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Sleep spindles are neurophysiological phenomena that appear to be linked to memory formation and other functions of the central nervous system, and that can be observed in electroencephalographic recordings (EEG) during sleep. Manually identified spindle annotations in EEG recordings suffer from substantial intra- and inter-rater variability, even if raters have been highly trained, which reduces the reliability of spindle measures as a research and diagnostic tool. The Massive Online Data Annotation (MODA) project has recently addressed this problem by forming a consensus from multiple such rating experts, thus providing a corpus of spindle annotations of enhanced quality. Based on this dataset, we present a U-Net-type deep neural network model to automatically detect sleep spindles. Our model’s performance exceeds that of the state-of-the-art detector and of most experts in the MODA dataset. We observed improved detection accuracy in subjects of all ages, including older individuals whose spindles are particularly challenging to detect reliably. Our results underline the potential of automated methods to do repetitive cumbersome tasks with super-human performance.
Die Oberflächen dentaler Implantate sind definiert durch eine raue Oberfläche, um die Integration in den menschlichen Knochen zu optimieren. Entzündungen des umgebenden Zahnfleisches zählen dabei zu den häufigsten Komplikationen nach einer Implantation. Diese Entzündungen entstehen hauptsächlich durch bakterielle Infektionen des Weichgewebes an der Implantations-Stelle. Die raue Oberfläche trägt jedoch zu einer solchen Infektion bei. Da der Implantat-Kopf zum Teil aus dem Knochen herausragt, erfolgt beispielsweise beim Zähneputzen eine Freilegung der Implantat-Oberfläche. Die durch die Rauheit vergrößerte Oberfläche bietet dabei ideale Voraussetzungen für eine Bakterienansiedlung. In der aktuellen Forschung steht die Entwicklung einer Oberfläche im Vordergrund, die eine antibakterielle Funktionalisierung erzeugt. Diese verhindert die Bakterienansiedlung und wirkt einer Entzündung entgegen. Um die Beschichtung vor Verschleiß zu schützen und ihre Lebensdauer der antibakteriellen Wirkung zu erhöhen, ist es möglich die Oberfläche mit einer
Mikrostruktur zu versehen.
Das Ziel der vorliegenden Arbeit ist die Identifikation geeigneter Mikrostrukturierungen, die der antibakteriellen Beschichtung einen optimalen Schutz vor Verschleiß bieten. Am Beispiel von Titan-Zahnimplantaten wird der Schutz der aufgetragenen Biohybridbeschichtung gegen abrasiven Verschleiß untersucht. Im Vorfeld wird eine Analyse der fertigungstechnischen Möglichkeiten mit Blick auf dentale Implantate und Mikrostrukturen durchgeführt, um das ein passendes Verfahren zu identifizieren. Die Analogiebauteile als Probenkörper werden, mithilfe des zuvor ausgewählten Verfahrens, mit verschiedenen Mikrostrukturen versehen. Im Rahmen einer Versuchsdurchführung, die die mechanische Belastung bei einem Zahnputzdurchgang imitiert, werden die verschiedenen Mikrostrukturen auf ihre Eignung für diese Anwendung überprüft. Ein Vorversuch dient zur Identifizierung eines geeigneten Ankerpeptids, welches den bindenden Bestandteil der Biohybridbeschichtung darstellt. Aus
drei zuvor ausgewählten Ankerpeptiden wird das mit der besten Adhäsionsfähigkeit herausgestellt. Im finalen Versuchsdurchlauf wird das Ankerpeptid auf die Oberflächen, die mit den Mikrostrukturen versehen sind, aufgetragen. Dabei ist das Ziel eine Mikrostruktur
herauszustellen, die den höchstmöglichen Schutz bietet.
Durch eine Fluoreszenzprüfung mithilfe eines Flourescence Plate Readers wird jede Kombination nach den Belastungsversuchen auf den Restanteil der Beschichtung überprüft.
Das Ergebnis stellt eine Mikrostruktur dar, die den bestmöglichen Schutz bietet. Dies ist erkennbar durch den höchsten Anteil an Restbeschichtung. Eine Strukturierung mit sogenannten Micro-Grooves in Kombination mit dem MacHis-Ankerpeptid erzielte in der Analyse der Belastungssimulationen die besten Ergebnisse bezüglich des Schutzes der Beschichtung. Durch die Versuche bestätigte sich eine weitere
Annahme. Die Strukturierung der Oberfläche erzielt einen deutlich höheren Schutz im Vergleich zu einer unstrukturierten Oberfläche. Zudem hat sich herausgestellt, dass eine Beschichtung mit dem sogenannten PEO-Verfahren eine deutlich größere Adhäsion der
Biohybridbeschichtung erzielt. Dies wird jedoch Thema weiterführender Forschungen sein und kein Bestandteil der vorliegenden Arbeit.
Contractile behavior of the gastrocnemius medialis muscle during running in simulated hypogravity
(2021)
Vigorous exercise countermeasures in microgravity can largely attenuate muscular degeneration, albeit the extent of applied loading is key for the extent of muscle wasting. Running on the International Space Station is usually performed with maximum loads of 70% body weight (0.7 g). However, it has not been investigated how the reduced musculoskeletal loading affects muscle and series elastic element dynamics, and thereby force and power generation. Therefore, this study examined the effects of running on the vertical treadmill facility, a ground-based analog, at simulated 0.7 g on gastrocnemius medialis contractile behavior. The results reveal that fascicle−series elastic element behavior differs between simulated hypogravity and 1 g running. Whilst shorter peak series elastic element lengths at simulated 0.7 g appear to be the result of lower muscular and gravitational forces acting on it, increased fascicle lengths and decreased velocities could not be anticipated, but may inform the development of optimized running training in hypogravity. However, whether the alterations in contractile behavior precipitate musculoskeletal degeneration warrants further study.
Plant viruses are major contributors to crop losses and induce high economic costs worldwide. For reliable, on-site and early detection of plant viral diseases, portable biosensors are of great interest. In this study, a field-effect SiO2-gate electrolyte-insulator-semiconductor (EIS) sensor was utilized for the label-free electrostatic detection of tobacco mosaic virus (TMV) particles as a model plant pathogen. The capacitive EIS sensor has been characterized regarding its TMV sensitivity by means of constant-capacitance method. The EIS sensor was able to detect biotinylated TMV particles from a solution with a TMV concentration as low as 0.025 nM. A good correlation between the registered EIS sensor signal and the density of adsorbed TMV particles assessed from scanning electron microscopy images of the SiO2-gate chip surface was observed. Additionally, the isoelectric point of the biotinylated TMV particles was determined via zeta potential measurements and the influence of ionic strength of the measurement solution on the TMV-modified EIS sensor signal has been studied.
Photoelectrochemical (PEC) biosensors are a rather novel type of biosensors thatutilizelighttoprovideinformationaboutthecompositionofananalyte,enablinglight-controlled multi-analyte measurements. For enzymatic PEC biosensors,amperometric detection principles are already known in the literature. In con-trast, there is only a little information on H+-ion sensitive PEC biosensors. Inthis work, we demonstrate the detection of H+ions emerged by H+-generatingenzymes, exemplarily demonstrated with penicillinase as a model enzyme on atitanium dioxide photoanode. First, we describe the pH sensitivity of the sensorand study possible photoelectrocatalytic reactions with penicillin. Second, weshow the enzymatic PEC detection of penicillin.
A new functionalization method to modify capacitive electrolyte–insulator–semiconductor (EIS) structures with nanofilms is presented. Layers of polyallylamine hydrochloride (PAH) and graphene oxide (GO) with the compound polyaniline:poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PANI:PAAMPSA) are deposited onto a p-Si/SiO2 chip using the layer-by-layer technique (LbL). Two different enzymes (urease and penicillinase) are separately immobilized on top of a five-bilayer stack of the PAH:GO/PANI:PAAMPSA-modified EIS chip, forming a biosensor for detection of urea and penicillin, respectively. Electrochemical characterization is performed by constant capacitance (ConCap) measurements, and the film morphology is characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). An increase in the average sensitivity of the modified biosensors (EIS–nanofilm–enzyme) of around 15% is found in relation to sensors, only carrying the enzyme but without the nanofilm (EIS–enzyme). In this sense, the nanofilm acts as a stable bioreceptor onto the EIS chip improving the output signal in terms of sensitivity and stability.
Miniaturized electrolyte–insulator–semiconductor capacitors (EISCAPs) with ultrathin gate insulators have been studied in terms of their pH-sensitive sensor characteristics: three different EISCAP systems consisting of Al–p-Si–Ta2O5(5 nm), Al–p-Si–Si3N4(1 or 2 nm)–Ta2O5 (5 nm), and Al–p-Si–SiO2(3.6 nm)–Ta2O5(5 nm) layer structures are characterized in buffer solution with different pH values by means of capacitance–voltage and constant capacitance method. The SiO2 and Si3N4 gate insulators are deposited by rapid thermal oxidation and rapid thermal nitridation, respectively, whereas the Ta2O5 film is prepared by atomic layer deposition. All EISCAP systems have a clear pH response, favoring the stacked gate insulators SiO2–Ta2O5 when considering the overall sensor characteristics, while the Si3N4(1 nm)–Ta2O5 stack delivers the largest accumulation capacitance (due to the lower equivalent oxide thickness) and a higher steepness in the slope of the capacitance–voltage curve among the studied stacked gate insulator systems.
This study reviews the practice of brake tests in freight railways, which is time consuming and not suitable to detect certain failure types. Public incident reports are analysed to derive a reasonable brake test hardware and communication architecture, which aims to provide automatic brake tests at lower cost than current solutions. The proposed solutions relies exclusively on brake pipe and brake cylinder pressure sensors, a brake release position switch as well as radio communication via standard protocols. The approach is embedded in the Wagon 4.0 concept, which is a holistic approach to a smart freight wagon. The reduction of manual processes yields a strong incentive due to high savings in manual
labour and increased productivity.
This study focuses on thermoelectric elements (TEE) as an alternative for room temperature control. TEE are semi-conductor devices that can provide heating and cooling via a heat pump effect without direct noise emissions and no refrigerant use. An efficiency evaluation of the optimal operating mode is carried out for different numbers of TEE, ambient temperatures, and heating loads. The influence of an additional heat recovery unit on system efficiency and an unevenly distributed heating demand are examined. The results show that TEE can provide heat at a coefficient of performance (COP) greater than one especially for small heating demands and high ambient temperatures. The efficiency increases with the number of elements in the system and is subject to economies of scale. The best COP exceeds six at optimal operating conditions. An additional heat recovery unit proves beneficial for low ambient temperatures and systems with few TEE. It makes COPs above one possible at ambient temperatures below 0 ∘C. The effect increases efficiency by maximal 0.81 (from 1.90 to 2.71) at ambient temperature 5 K below room temperature and heating demand Q˙h=100W but is subject to diseconomies of scale. Thermoelectric technology is a valuable option for electricity-based heat supply and can provide cooling and ventilation functions. A careful system design as well as an additional heat recovery unit significantly benefits the performance. This makes TEE superior to direct current heating systems and competitive to heat pumps for small scale applications with focus on avoiding noise and harmful refrigerants.
Formine 2019 : In Cima
(2019)