Scientific publications of the Saarland University
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Multi-Level Simulation Framework for Degradation-Aware Operation of a Large-Scale Battery Energy Storage Systems
Full text linkThe increasing integration of renewable energy sources necessitates efficient
energy storage solutions, with large-scale battery energy storage systems (BESS) playing
a key role in grid stabilization and time-shifting of energy. This study presents a multi level simulation framework for optimizing BESS operation across multiple markets while
incorporating degradation-aware dispatch strategies. The framework integrates a day ahead (DA) dispatch level, an intraday (ID) dispatch level, and a high-resolution simulation
level to accurately model the impact of operational strategies on state of charge and battery
degradation. A case study of BESS operation in the German electricity market is conducted,
where frequency containment reserve provision is combined with DA and ID trading. The
simulated revenue is validated by a battery revenue index. The study also compares full
equivalent cycle (FEC)-based and state-of-health-based degradation models and discusses
their application to cost estimation in dispatch optimization. The results emphasize the
advantage of using FEC-based degradation costs for dispatch decision-making. Future
research will include price forecasting and expanded market participation strategies to
further improve and stabilize the profitability of BESS in multi-market environments
A Systematic Review and Meta-Analysis on the Safety of Antiplatelet Discontinuation Following Stent-Assisted Coil Embolization for Cerebral Aneurysms
Full text linkBackground: Stent-assisted coil embolization (SACE) is a common endovascular
technique for managing intracranial aneurysms. The permanent presence of a stent inside
the cerebral artery necessitates the postoperative use of antiplatelets. However, a consensus
about how long to continue on it remains debated. This systematic review aims to discuss
and quantify the risk of ischemic complications after antiplatelet discontinuation following
SACE. Methods: PubMed, Cochrane Library, Scopus, and Web of Science (WOS) were
systematically searched for studies assessing the outcomes after antiplatelet discontinuation
following SACE for cerebral aneurysms. The primary outcome was the odds of ischemic
complications after antiplatelet discontinuation. Using a random-effects model, the pooled
event rate, along with a 95% confidence interval (CI), was calculated. The Comprehensive
Meta-Analysis software (CMA) software was used for the analysis. The Newcastle–Ottawa
Scale (NOS) was used for the quality assessment. Results: A total of five observational
cohort studies were included in this systematic review. The studies recruited cases from
2009 and 2020, predominantly in Korea and Japan. Data from 18,425 cases obtained
from four studies were analyzed. The duration of antiplatelet therapy varied widely
across the included studies. Additionally, most studies reported a median follow-up of
24 months or more after antiplatelet discontinuation. We extracted and analyzed the odds
of thromboembolic complications occurring within 6 to 24 months after the discontinuation
of antiplatelets. The pooled rate of thromboembolism after antiplatelet discontinuation in
this meta-analysis was 0.01 (95% CI: 0.006 to 0.018). Conclusion: This review demonstrates
that the risk of thromboembolic complications after discontinuing antiplatelet therapy post SACE is low. However, no strong consensus exists on the ideal duration for maintaining
dual- or single-antiplatelet therapy. Further prospective studies with longer follow-ups are
warranted to clarify the optimal durations needed to balance thromboembolic risk with
hemorrhagic complications
Historical View and Some Unsolved Problems in Red Blood Cell Membrane Research
Full text linkThe article provides a comprehensive overview of biological membrane lipid composition and distribution and ion transport processes, focusing particularly on red blood cells (RBCs). It begins with a historical perspective, detailing the introduction of the terms 'cell' and 'membrane' in biological sciences, and the development of the fluid-mosaic model of membrane structure. Early findings on ion transport highlighted the non-equilibrium distribution of Na+ and K+ across cell membranes, leading to the discovery of the Na+/K+ pump. The article delves into the lipid composition of RBC membranes, emphasising the roles of various lipids, including cardiolipin, and the concept of lipid rafts. These rafts, enriched with sphingolipids and cholesterol, play crucial roles in cellular processes. Variations in RBC shapes are discussed, with biophysical theories explaining transformations and pathological conditions affecting RBC morphology, such as sickle cell anaemia. Na+ and K+ transporters in RBC membranes are explored, highlighting the almost ubiquitous presence of the Na+/K+ pump (absent in Carnivora RBCs) and various ion channels, including the Gárdos and Piezo1 channels. The article notes species-specific differences in ion transport mechanisms and the activation or suppression of transporters during RBC maturation. The mechanism of residual ion transport is examined, questioning whether a Na+(K+)/H+ antiporter exists in the human RBC membrane. Residual ion fluxes are mediated by this antiporter, influenced by the fatty acid composition of the RBC membrane. The outlook section underscores the need for further research to fully understand the complexities of RBC membrane structure and function, suggesting that many questions remain unanswered despite significant advances
Modulating fear processes: Exploring the effects of intranasal insulin, glucose, and COVID-19 anxiety in classical fear conditioning
Full text linkAnxiety disorders are among the most common mental illnesses world-wide and are of considerable public health importance due to their high prevalence (Wittchen et al., 2011). Despite the availability of effective treatments for anxiety disorders, millions of people suffer from symptoms that interfere with their daily lives, resulting in persistent distress and reduced overall quality of life (Craske et al., 2009). Within cognitive behavioral therapy, exposure therapy has been shown to be a successful treatment option for many anxiety disorders. Exposure involves systematically exposing patients to anxiety-provoking stimuli in a controlled and safe environment until the fear response diminishes. Despite its high efficacy, not all anxiety patients benefit equally from the therapy, and there are always dropouts, incomplete recovery, or relapse of symptoms (Arch & Craske, 2009). The development and treatment of anxiety disorders can be explained in part by processes of classical conditioning, in which neutral stimuli are given negative meanings through association learning (Duits et al., 2015). Classical models of fear conditioning help to understand the development, maintenance and treatment of anxiety disorders. At the same time, environmental factors, such as traumatic experiences or stressful life events, can play a central role in the development and progression of anxiety disorders. Stress can dysregulate neurobiological systems, particularly the limbic system and the amygdala, and thus increase vulnerability to the development of anxiety disorders (Garakani et al., 2006). Recent global events, such as the COVID-19 pandemic and other crises, may exacerbate these processes through chronic stress, leading to a further increase in the prevalence of anxiety disorders (Kazmi et al., 2020). It is essential to find ways to improve the treatment options for anxiety disorders, in particular to further improve exposure therapy. In addition to the use of classical psychotropic drugs, which are administered in addition to exposure therapy, the use of so-called cognitive enhancers, i.e. substances that influence neurocognitive processes such as attention, memory and learning, is proving to be promising. Studies have identified several such substances that have already shown positive effects in the context of fear extinction, including hormones such as oxytocin or cortisol (Brueckner et al., 2019; de Quervain et al., 2009; Eckstein et al., 2015, 2019). The aim of the present dissertation is to investigate the role of environmental stress and cognitive enhancers as modulating factors of fear conditioning processes. Several aims were pursued and a total of three empirical studies were conducted. The first study aimed to investigate the potential of intranasally administered insulin as a cognitive enhancer in the extinction of fear. To this end, a classical fear conditioning study was conducted with healthy subjects. Before extinction, the subjects were administered either insulin or a placebo by nasal spray. Subjects in the insulin group showed a greater reduction in the fear response during extinction, a first indication of the beneficial effect of intranasal insulin as a cognitive enhancer of fear extinction. The second study investigated the impact of anxiety related to the COVID-19 pandemic on fear learning and fear generalization. The aim was to investigate whether increased anxiety during COVID-19 can lead to increased conditionability and generalization of fear. To this end, a classical fear conditioning study was conducted with healthy subjects and COVID-19-related anxiety was measured. Subjects with higher COVID-19-related anxiety tended to discriminate poorly between safe and dangerous stimuli during fear learning and to generalize their fear response more strongly. Based on the results of the first study, the third study investigated whether the administration of glucose as a cognitive enhancer could improve the effects of fear extinction. Two fear conditioning studies were conducted in healthy subjects, in which the subjects were given either glucose or a placebo before (Study 1) or after (Study 2) extinction. Subjects in the glucose group showed a greater reduction in fear during extinction (Study 1) and during a later recall (Study 2), providing preliminary evidence for the efficacy of glucose as a cognitive enhancer in fear extinction. In conclusion, the three studies presented in this dissertation provide important insights for current research on fear extinction processes and their possible enhancement by cognitive enhancers such as insulin or glucose. Furthermore, the importance of environmental stressors in the development and maintenance of anxiety disorders is highlighted by the demonstrated influence of COVID-19-related anxiety on important fear learning processes such as fear generalization. By integrating the knowledge gained, the studies contribute to a better understanding of fear learning processes and lay the foundation for further research to gain practical implications for improving exposure therapy.Angststörungen zählen zu den häufigsten psychischen Erkrankungen weltweit und haben aufgrund der hohen Prävalenz eine erhebliche Bedeutung für die öffentliche Gesundheit (Wittchen et al., 2011). Obwohl es eine effektive Therapie gegen Angststörungen gibt, leiden Millionen von Menschen unter Symptomen, die das alltägliche Leben erschweren und so zu einer anhaltenden Belastung und Verringerung der allgemeinen Lebensqualität führen (Craske et al., 2009). In der kognitiven Verhaltenstherapie hat sich die Expositionstherapie als bewährte Therapieoption zur erfolgreichen Behandlung vieler Angststörungen erwiesen. Während der Exposition werden die PatientInnen systematisch mit den angstauslösenden Reizen in einer kontrollierten und sicheren Umgebung konfrontiert, bis die Angstreaktion abnimmt. Trotz hoher Effektivität, profitieren nicht alle AngstpatientInnen gleichermaßen von der Therapie und es kommt immer wieder zu Therapieabbrüchen, einer unvollständigen Genesung oder einem Rezidiv der Symptomatik (Arch & Craske, 2009). Die Entstehung und Behandlung von Angststörungen kann unter anderem durch Prozesse klassischer Konditionierung erklärt werden, bei denen neutralen Reizen durch Assoziationslernen eine negative Bedeutung zugeschrieben wird. Klassische Angstkonditionierungsmodelle helfen die Entstehung, Aufrechterhaltung und Behandlung von Angststörungen zu verstehen. Gleichzeitig können Umweltfaktoren, wie traumatische Erlebnisse oder stressige Lebensereignisse eine zentrale Rolle bei der Entstehung und dem Verlauf von Angststörungen spielen. Stress kann neurobiologische Systeme, insbesondere das limbische System und die Amygdala dysregulieren und so die Anfälligkeit für die Entwicklung von Angststörungen erhöhen (Garakani et al., 2006). Aktuelle globale Ereignisse, wie die COVID-19 Pandemie und andere Krisen können diese Prozesse durch chronischen Stress verschärfen, und so zu einer weiter steigenden Prävalenz von Angststörungen führen (Kazmi et al., 2020). Es ist von zentraler Bedeutung Wege zu Verbesserung von Therapieoptionen für Angststörungen, insbesondere zur weiteren Verbesserung der Expositionstherapie, zu finden. Neben dem Einsatz von zusätzlich zur Expositionstherapie verabreichten klassischen Psychopharmaka, erweist sich die Verwendung von so-genannten kognitiven Verstärkern, also Substanzen, welche neurokognitive Prozesse wie Aufmerksamkeit, Gedächtnis und Lernen beeinflussen, als vielversprechend. Studien haben mehrere solcher Substanzen identifiziert, welche bereits im Kontext der Angstextinktion positive Effekte zeigten, darunter Hormone wie Oxytocin oder Cortisol (Brueckner et al., 2019; de Quervain et al., 2009; Eckstein et al., 2015, 2019). Ziel der vorliegenden Arbeit ist es, die Rolle von Umweltstress und kognitiven Verstärkern als modulierende Faktoren von Angstkonditionierungsprozessen zu untersuchen. Dabei wurden mehrere Ziele verfolgt und insgesamt drei empirische Studien durchgeführt. Ziel der ersten Studie war es das Potential von intra-nasal verabreichtem Insulin als kognitiver Verstärker bei der Extinktion von Angst zu untersuchen. Zu diesem Zweck wurde eine klassische Angstkonditionierungsstudie mit gesunden ProbandInnen durchgeführt. Vor der Extinktion wurde den ProbandInnen entweder Insulin oder ein Placebo per Nasenspray verbreicht. ProbandInnen der Insulingruppe zeigten eine stärkere Abnahme der Angstreaktion während der Extinktion, was einen ersten Hinweis für die förderliche Wirkung von intranasalem Insulin als kognitiver Verstärker der Angstextinktion darstellt. In der zweiten Studie wurde untersucht, wie sich auf die COVID-19 Pandemie bezogene Ängste auf das Angstlernen und die Angstgeneralisierung aus-wirken. Ziel war es zu untersuchen, ob eine erhöhte Ängstlichkeit während CO-VID-19 zu einer verstärkten Konditionierbarkeit und Generalisierung von Angst führen kann. Dazu wurde eine klassische Angstkonditionierungsstudie mit gesunden ProbandInnen durchgeführt und die COVID-19 bezogene Ängstlichkeit gemessen. ProbandInnen mit höherer COVID-19 bezogener Ängstlichkeit zeigten eine Tendenz zur schlechteren Diskriminierung zwischen sicheren und gefährlichen Reizen während des Angstlernens sowie eine stärker ausgeprägte Generalisierung der Angstreaktion. Aufbauend auf den Ergebnissen der ersten Studie wurde in der dritten Studie untersucht, ob die Verabreichung von Glukose als kognitiver Verstärker die Effekte der Angstextinktion verbessern kann. Es wurden zwei Angstkonditionierungsstudien mit gesunden ProbandInnen durchgeführt, bei denen den ProbandInnen vor (Studie 1) bzw. nach der Extinktion (Studie 2) entweder Glukose oder ein Placebo verabreicht wurde. ProbandInnen der Glukosegruppe zeigten eine stärkere Abnahme der Angstreaktion während der Extinktion (Studie 1) und einem späteren Abruf (Studie 2), was einen ersten Beleg für die Wirksamkeit von Glukose als kognitiver Verstärker bei der Extinktion von Angst darstellt. Zusammenfassend liefern die drei in dieser Arbeit vorgestellten Studien wichtige Erkenntnisse für die aktuelle Forschung zu Prozessen der Angstextinktion und beispielsweise deren mögliche Verbesserung durch kognitive Verstärker wie Insulin oder Glukose. Zudem wird die Bedeutung von umweltbezogenen Stressfaktoren auf die Entstehung und Aufrechterhaltung von Angststörungen durch den nachgewiesenen Einfluss des COVID-19 bezogenen Angsterlebens auf wichtige Angstlernprozesse, wie die Generalisierung von Angst, unterstrichen. Durch die Integration der gewonnenen Erkenntnisse tragen die Studien zu einem besseren Verständnis von Angstlernprozessen bei und legen dabei den Grund-stein für weitere Forschung, um mit deren Hilfe praktische Implikationen für die Verbesserung der Expositionstherapie gewinnen zu können
Prone positioning improves surgical access to the thoracolumbar junction - An MRI pilot study
Full text linkBackground: The lateral decubitus position is the standard position for a lateral approach of the thoracolumbar
junction, but prone positioning has been observed to increase the distance of abdominal organs from the spine in
comparison to lateral decubitus position and gives a safe exposure to the lumbar spine.
Purpose: To compare distances between the thoracolumbar spine junction and abdominal structures between
lateral decubitus and prone position.
Methods: Magnetic resonance imaging was conducted in two positions, lateral decubitus and prone, in six vol unteers with no previous spine injury or complaints. Distances of abdominal structures from the spine were
measured from Th10 to S1.
Results: In lateral decubitus position, abdominal structures shifted away from the thoracolumbar junction on the
left side but became nearer to the spine on the right side. The distance of abdominal structures from the spine was
highest in prone position, particularly on the right side.
Conclusions: These anatomical descriptions suggest that prone position can improve surgical access to the
thoracolumbar junction in comparison to the standard lateral decubitus position, from the right side as well as
from the left side
Multifunctional dielectric elastomer transducers as integrated audio-tactile interfaces with self-sensing capability
No full textDielectric elastomer transducers (DET) offer many advantages over conventional electro-mechanical drives due to their high energy efficiency, low weight and simultaneous usability as actuator and sensor. This dissertation focuses on the use of DEs as multifunctional elements, to develop fundamentally new and inventive systems for human interaction. Through the developed advanced control of a single DET device, different structural resonance ranges of DETs are stimulated and experimentally validated. With the investigated and characterised new operating principle of DETs, multifunctional elements with tactile and simultaneous acoustic feedback, as well as input detection capabilities, are realised the first time. With this innovative principle, a lean and highly integrated audio-tactile feedback unit with self-sensing capability is developed in a systematic optimization process. This enables the extension of sensor and pure haptic systems by multifunctional interaction. The developed elements, principles, processes and manufacturing methods are systematically described and experimentally validated. The sensor and actuator properties of the developed multifunctional systems as well as their applicability in many application areas, are identified and validated by methodical measurements and subject surveys. In summary, innovative and systematic concepts and application-oriented solutions for DET-based user interfaces, as assistance tools and smart textile integrated composite systems, are developed.Dielektrische Elastomere (DE) bieten durch ihre hohe Energieeffizienz, ihr geringes Gewicht und ihre gleichzeitige Verwendbarkeit als Aktor und Sensor viele Vorteile gegenüber herkömmlichen elektromechanischen Antrieben. Diese Dissertation konzentriert sich auf die Verwendung von DEs als multifunktionale Elemente, um grundlegend neue und innovative Systeme für die menschliche Interaktion zu entwickeln. Durch die entwickelte erweiterte Ansteuerung eines einzelnen DE-Elements, werden verschiedene strukturelle Resonanzbereiche von DEs angeregt und experimentell validiert. Mit dem untersuchten und charakterisierten neuen Funktionsprinzip von DEs werden erstmals multifunktionale Elemente mit taktiler und gleichzeitiger akustischer Rückmeldung, sowie Eingabeerfassungsmöglichkeiten realisiert. Mit diesem innovativen Prinzip wird in einem systematischen Optimierungsprozess eine schlanke und hochintegrierte audio-taktile Feedback-Einheit mit Self-Sensing-Fähigkeit entwickelt. Dies ermöglicht die Erweiterung von sensorischen und rein haptischen Systemen um eine multifunktionale Interaktionsebene. Die entwickelten Elemente, Prinzipien, Prozesse und Fertigungsmethoden werden systematisch beschrieben und experimentell validiert. Die sensorischen und aktorischen Eigenschaften der entwickelten multifunktionalen Systeme, sowie deren Anwendbarkeit in vielen Anwendungsbereichen, werden vorgestellt und durch methodische Messungen und Probandenbefragungen validiert. Zusammenfassend werden innovative und systematische Konzepte und anwendungsorientierte Lösungen für DE-basierte Benutzerschnittstellen als Assistenzwerkzeuge und intelligente textile Verbundsysteme entwickelt
The Plus End-Directed Microtubule (Kinesin-3 Family) Motor Protein KIF13B Is Associated with the Photoreceptor Synaptic Ribbon Complex
Full text linkRetinal ribbon synapses are continuously active chemical synapses. The eponymous synap tic ribbon is anchored to the active zone neurotransmitter release sites of ribbon synapses,
recruits synaptic vesicles and guides ribbon-associated synaptic vesicles to the release sites.
RIBEYE is the major protein component of synaptic ribbons. But likely, additional proteins
contribute to ribbon synapse function. The synaptic ribbon of photoreceptor synapses is
embedded into a highly polarized microtubule cytoskeleton. Interestingly, proteins of the
photoreceptor primary cilium, such as NPHP4 and other ciliary proteins, including KIF3A,
were shown to be localized to photoreceptor synaptic ribbons. Previous studies demon strated that the microtubule motor protein KIF13B catalyzes secretory vesicle transport
to the plus ends of microtubules and identified an interaction of KIF13B with NPHP4 at
primary cilia. However, the localization of KIF13B, a kinesin-3 family motor protein, in
the retina is still unknown. In the present study, we used two different antibodies against
KIF13B and high-resolution confocal microscopy, super-resolution structured illumination
microscopy (SR-SIM), and post-embedding immunogold electron microscopy to determine
the localization of KIF13B in retinal photoreceptors. Apart from its localization at the
primary photoreceptor cilium, we found a strong enrichment of KIF13B at photoreceptor
synaptic ribbons. The synaptic ribbon is needed for the synaptic enrichment of KIF13B as
shown by analyses of synaptic ribbon-deficient RIBEYE knockout mice. These findings
suggest that KIF13B performs vesicle trafficking functions at the photoreceptor synaptic rib bon complex at the interface between the synaptic ribbon and the presynaptic microtubule
transport system
Grain growth simulation of steels during heat treatment with statistically modeled discrete neighborhood
Full text linkA new grain growth model is proposed that extends classical mean-field models to include the local neighborhood of grains. The theoretical basis of the approach is the equilibrium angle of grain boundaries at triple junctions, which is estimated to be 120°considering 2 dimensions, in the case of isotropic grain boundary energy. Based on this fact and a size comparison of individual grains, an algorithm is developed that assigns a discrete neighborhood relationship to all grains, resulting in the generation of an artificial microstructure. For validation, samples of a CMn steel were examined in different states after heat treatments and the microstructure was characterized using deep learning approaches to extract grain boundaries from etched samples with excellent statistics and reliability. The properties and statistical characteristics of the artificial and real microstructures are presented and compared. It is shown that simple topological approaches, such as the linear relationship between the number of grain neighbors and the relative grain size, are good only in a first approximation, but collapse in detail. The proposed model is able to resemble these small deviations of a real microstructure from topological models. Furthermore, the grain growth behavior of such an artificial microstructure is compared with real grain growth experiments. The comparison shows that by implementing the discrete neighborhood of grains, behaviors such as abnormal grain growth seem to be covered to a certain extent without additional treatment as required in other models
Evaporation-triggered nanoprecipitation for PLGA nanoparticle formation using a spinning-disc system
Full text linkResearchers have successfully introduced many formulations based on nanoparticles and many of those products are already available for clinical use. When it comes to polymeric nanoparticles, there are only natural polymers (e.g., albumin) approved but several publications describe very promising results at the laboratory level. Poly (lactic-co-glycolic acid) (PLGA) is widely used by researchers to prepare nanoparticles and there are several publications available with very promising results at the laboratory level but there are barely any approaches for commercial production of PLGA nanoparticles. One of the main challenges is the difficulty in converting lab scale production into commercial scale production. This study describes a very innovative manufacturing technology i.e. spinning disc system (SDS) for the continuous manufacturing of PLGA nanoparticles. It relies on a one-pot process, i.e. polymer, organic phase, aqueous phase and drug are homogeneously distributed and mixing as critical process parameter is eliminated. Centrifugal force causes the solution to spread all over the rotating disc and the large surface area of the disc facilitates the evaporation of the organic phase resulting in polymer precipitation. This manufacturing method also enables tuning of particle size (a wide range of between 120 and 320 nm can be achieved). Compared to standard bench top (BT) methods, smaller particles with higher yields were obtained (141 nm with a yield of 89 %). Along with continuous production of nanoparticles, SDS also improves encapsulation efficiency and drug loading of PLGA nanoparticles. Curcumin (CUR) as a model drug substance was encapsulated with SDS with a high encapsulation efficiency (60–70 %) compared to only 10–25 % in BT. Subsequently, a drug loading twice as high as with BT was achieved using SDS. The nanoparticles prepared with or without stabilizer produced nearly monodisperse particle sizes (PDI <0.1) and showed negative zeta-potentials (<−30 mV), which showed promising colloidal stability over a test period of 28 days. Maximum 7.4 nm of deviation from initial size was observed in stability studies
Invisible eyes: Real-time activity detection through encrypted Wi-Fi traffic without machine learning
No full textWi-Fi camera-based home monitoring systems are increasingly popular for improving security and real-time observation. However, reliance on Wi-Fi introduces privacy vulnerabilities, as sensitive activities within monitored areas can be inferred from encrypted traffic. This paper presents a lightweight, non-ML attack model that analyzes Wi-Fi traffic metadata—such as packet size variations, serial number sequences, and transmission timings—to detect live streaming, motion detection, and person detection. Unlike machine learning-based approaches, our method requires no training data or feature extraction, making it computationally efficient and easily scalable. Empirical testing at varying distances (10 m, 20 m, and 30 m) and under different environmental conditions shows accuracy rates of up to 90% at close range and 72% at greater distances, demonstrating its robustness. Compared to existing ML-based techniques, which require extensive retraining for different camera manufacturers, our approach provides a universal and adaptable attack model. This research underscores significant privacy risks in Wi-Fi surveillance systems and emphasizes the urgent need for stronger encryption mechanisms and obfuscation techniques to mitigate unauthorized activity inference