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Magnetic nanoparticles (MNP) serve as imaging tracers, therapeutic heating agents and biosensors in biomedical applications. All the above applications rely upon the particles’ unique relaxation mechanisms, which lead to phase shifts in alternating magnetic fields and dissipation. As MNP have an intrinsic size distribution and their magnetic properties are also size-dependent, search is ongoing for the optimally sized MNP that could potentially serve for all three applications simultaneously. In this work, we present our current results on simulating the influence of core size, mono- and polydisperse size distributions as well as magnetic anisotropy on the performance of MNP for both heating and biosensing using micromagnetic dynamic magnetization simulations.
Magnetic nanoparticles (MNP) enable new biomedical applications as imaging tracers, heating agents or biosensors due to their unique relaxation mechanism in alternating magnetic fields. For assessing MNP suitable for such applications, magnetic particle spectroscopy (MPS) offers a reliable method, dual-frequency excitation adding sensitivity. Biomedical applications, however, rely on MNP use in physiological environments (blood, tissue, etc.) of various viscosities, which could strongly alter the MNP relaxation behavior. In this work, we present our preliminary results of varying viscosity on the relaxation of MNP during dual-frequency MPS, studied with micromagnetic dynamic magnetization simulation.
Magnetic Particle Spectroscopy (MPS) allows for direct characterization of magneto-physical properties of magnetic nanoparticles (MNP), which are widely researched as imaging tracers, biosensing units and therapeutic heating agents. All these applications rely primarily on the core size-dependent magnetic particle relaxation dynamics. Therefore, knowledge about core size of any MNP sample is crucial. Dual-frequency MPS increases the characterization potential by considering frequency mixing terms of the received signal of MNP, from which their sizes can be approximated. In this work, preliminary feasibility and interpretation of a proposed size reconstruction method is tested against precisely simulated input data from stochastically coupled Néel-Brownian relaxation modeling using Monte Carlo implementation.
The development of information retrieval and extraction systems is still a challenging task. The occurrence of natural language limits the application of existing approaches. Therefore the approach of a new framework which combines natural language processing and semantic web technology is discussed.
This paper focuses on ontology based knowledge modelling for semantic data extraction. Therefore, semantic verification techniques which can be used to improve the extraction are introduced.
ARTIFACT: Architecture for Automated Generation of Distributed Information Extraction Pipelines
(2022)
Companies often have to extract information from PDF documents by hand since these documents only are human-readable. To gain business value, companies attempt to automate these processes by using the newest technologies from research. In the field of table analysis, e.g., several hundred approaches were introduced in 2019. The formats of those PDF documents vary enormously and may change over time. Due to that, different and high adjustable extraction strategies are necessary to process the documents automatically, while specific steps are recurring. Thus, we provide an architectural pattern that ensures the modularization of strategies through microservices composed into pipelines. Crucial factors for success are identifying the most suitable pipeline and the reliability of their result. Therefore, the automated quality determination of pipelines creates two fundamental benefits. First, the provided system automatically identifies the best strategy for each input document at runtim e. Second, the provided system automatically integrates new microservices into pipelines as soon as they increase overall quality. Hence, the pattern enables fast prototyping of the newest approaches from research while ensuring that they achieve the required quality to gain business value.
Even though being a standard procedure in cardiac surgery, cardiopulmonary bypass (CPB) is associated with a 2-3% stroke prevalence, which increases towards 13% in high risk patients. Stroke can be caused by diminished brain perfusion and release of atherosclerotic plaques. Both are related to altered flow conditions in the aortic arch induced by the outflow cannula. By optimizing the cannula design, brain perfusion can be increased during CPB while decreasing stress on calcified aortic walls.
Haben Sie sich schon einmal darüber geärgert, dass einige Dozenten, Gruppenleiter oder Kollegen einfach nicht verständlich erklären können? Oder vielleicht sogar selber geflucht, weil einige der lieben Kollegen die Erklärungen, die man ihnen so ausführlich gegeben hat, einfach nicht verstehen (wollen)? Haben Sie auch schon einmal auf einen Spieleabend frustriert einer extrem umständlichen Erklärung der Spielregeln eines neuen Spiels zuhören müssen? So etwas ist nicht nur ärgerlich, es kann im professionellen Umfeld sogar richtig teuer oder gar gefährlich werden. Aber wer trägt die Schuld daran: Die/Derjenige, die/der’s vielleicht unzureichend erklärt hat? Die/derjenige, die/der die gegebenen Informationen nicht adäquat aufnimmt und umsetzt? Oder ist manche Thematik vielleicht so abgehoben, dass sie sich einer nachhaltigen Erklärung einfach grundsätzlich entzieht? Woran könnte es bloß liegen, dass mündlich weitergegebene Informationen allzu oft nicht behalten oder nicht im beabsichtigten Sinne praktisch umgesetzt werden? Wer diese Schuldfrage ein für alle Mal geklärt haben will, komme bitte nicht zu diesem Workshop. Denn wir werden drei prototypische Erklärungsszenarien unter die Lupe nehmen, um uns konstruktiv mit der Frage auseinanderzusetzen, wie gutes Erklären ablaufen kann. Wir werden gemeinsam erfahren, dass eine Erklärung, die der Empfänger memorieren und zielführend umsetzen kann, aus mehr als geschickt gewählten Wörtern besteht. Und dass auch mit der aktuellen Fokussierung auf digitale Kommunikationswege leider auch einige weitere Hürden hinzugekommen sind. Im Workshop werden wir in drei ersten Übungen grundlegende Kriterien, Regeln, Hinweise und Tipps identifizieren, die dafür sorgen, dass analoge und digitale Erklärungen im Sinne der/des Erklärenden die beabsichtigte Wirkung zeigen – oder warum sie das manchmal auch mal nicht tun.
What does the future biomedical engineering graduate need for a successful transition into industrial career? Modern industry and multi-discipline projects require highly trained individuals with resilient science and engineering backgrounds. These graduates must be able to agilely apply excellent theoretical knowledge in their subject matter as well as essential practical “hands-on” knowledge of diverse working processes to solve complex problems. To meet these demands placed on graduates, university education follows the concept of Constructive Alignment and thus increasingly adopts the teaching of necessary practical skills to the actual industry requirements and respective assessment routines. However, a systematic approach to coherently align these three central teaching demands is strangely absent from current university curricula.
Warum betreiben Menschen den logistischen, technischen und finanziellen Aufwand, sich in Meetings zu treffen? Weil sie das gemeinsame Verständnis zu einer bestimmten Sache voranbringen möchten und in der Hoffnung, im gemeinsamen Austausch weiter planen, besser entscheiden oder einfach mehr schaffen zu können, als allein. Im Kern jedes Meetings – ob im Privaten oder im Beruflichen – stehen die Wünsche, das gemeinsame Verständnis zu einer Sache zu vergrößern und Gedankengänge zu beschreiten, die nur in der kreativen Gemeinschaft entstehen können. Oder in den Worten von Hellmut Geißner „etwas gemeinsam zur Sache zu machen“ bzw. „etwas zur gemeinsamen Sache zu machen“. In der grundsätzlichen Idee ist uns das Konzept allen einleuchtend, aber in der Umsetzung erleben wir doch immer wieder einschränkende organisatorische Hindernisse oder lähmende methodische Abläufe. Um für alle Teilnehmenden und für uns selbst ein erfolgreiches Meeting durchführen zu können, sollten wir uns daher bereits im Vorfeld fragen: Was kann ich tun, um mein Meeting besser zu organisieren? Wo kann ich ansetzen, um den Erfolg des Meetings zu heben? Wir betrachten diese Fragen aus Sicht eines Moderators und stellen praktikable und konkrete Methoden und Ansätze zur Planung, Durchführung und Dokumentation von Meetings vor.
Cardiopulmonary bypass (CPB) is a standard procedure in cardiac surgery, with a 2-3% stroke prevalence, increasing towards 13% in high risk patients. Among the main reasons for stroke are diminished brain perfusion and release of atherosclerotic plaques, which are both related to altered flow conditions in the aortic arch caused by the outflow cannula. Here, we present an optimized cannula design (optiCAN), which increases brain perfusion during CPB while decreasing stress on potentially calcified aortic walls. This could reduce the prevalence of stroke in high risk patients, while maintaining a small incision site and minimal blood trauma.
Magnetic fluid hyperthermia (MFH) enables the controlled release of therapeutical heat using magnetic nanoparticles (MNP) as heating agents. The MNP are excited in an externally applied alternating magnetic f ield (AMF). The excitation energy is transformed into heat via magnetic relaxation of the MNP. This heat is then dissipated into their immediate surroundings, e. g. a tumor, facilitating the therapy of organ-confined cancer. Treatment efficacy relies on MFH efficiency to generate heat, which is dependent on the MNP interaction with their environment. Here, different approaches of modelling this interaction well as corresponding in vitrostudies are discussed with respect to two different applications: MFH after magnetic targeting of MNP to a tumor site and MFH through inductive heatable stents with incorporated MNP for treatment of endoluminal tumors. For these applications, MNP are restricted in their mobility and form clusters, which influences their magnetic relaxation and heating behavior. Using theoretical modelling techniques, sets of parameters are predicted which match field amplitude and frequency to MNP size and magnetic properties for optimized MFH efficiency. For the magnetic targeting application, the MNP interaction with tumor cells and its impact on heating efficiency is estimated by heating experiments on MNP immobilized in hydrogels, mimicking the settings in cellular environments such as binding to cell membranes and agglomeration inside lysosomes. Such hydrogels have tunable material properties that allow to quantify the effects of clustering and immobilization on particle heating. Further, the general feasibility of MFH is addressed with in vitro MFH experiments carried out with pancreatic tumor cells. Besides the obvious bulk temperature cytotoxic effect, the so-called nanoheating effect, i. e. heat developed up to 100 nm away from the MNP surface, is demonstrated. For the inductive heatable stents, different MNP are investigated concerning their concentration, immobilization and agglomeration effects on heating efficiency. The dipolar particle-particle interaction and the effective anisotropy energy increase for MNP agglomerates, directly influencing their non-linear dynamic magnetic susceptibility. Since hyperthermia and magnetic paticle imaging (MPI) rely on the non-linear dynamic magnetic susceptibility, the same behavior is observed in both techniques. So, the imaging performace of the stents is also presented.
Magnetic fluid hyperthermia (MFH) enables the controlled release of therapeutical heat using magnetic nanoparticles (MNP) as heating agents. The MNP are triggered to transform the energy of an externally applied alternating magnetic field into heat via relaxation of their magnetic moments. This heat is then dissipated into their immediate surroundings, e.g. a tumor, facilitating organ confined cancer treatment. While offering great potential in minimally-invasive localized cancer therapy, MFH efficacy relies on MNP efficiency to generate heat in interaction with the biological environment. Among other things, MNP are restricted in their mobility and form clusters under these physiological conditions, overall alternating their magnetic relaxation and heating behavior. Here, current approaches ranging from theorectical modelling to preclinical application of MFH are presented, specifically addressing MNP heating under these alternations. Particle heating modelling techinques are developed, predicting sets of parameters matching field amplitude and frequency as well as MNP size and magnetic properties for optimized MFH efficiency. The MNP interaction with tumor cells and its impact on heating efficiency is quantified and validated with heating experiments on MNP immobilized in hydrogels, mimicking the settings in cellular environments such as binding to the cell membranes and agglomeration inside lysosomes. These hydrogels have tunable materials properties that allow to quantify the effects of clustering and immobilization on the particle heating. Further, the general feasibility of MFH is addressed with in-vitro MFH experiments carried out on pancreatic tumor cells. Beyond the obvious bulk temperature cytotoxic effect, the so-called nanoheating effect is demonstrated. This effect underscores the use of MNP as therapeutical agents, which, combined with their use as diagnostic agents in magnetic particle imaging (MPI), display a promising theranostic platform for future biomedical applications.
Magnetic Fluid Hyperthermia (MFH) offers a potent alternative for the treatment of local tumors. In MFH, magnetic nanoparticles (MNP) are either injected directly into or targeted magnetically at the tumor site, where they are exposed to an oscillating magnetic field (OMF). Driven by the OMF the MNP undergo relaxation and hysteretic processes, generating heat locally. It was demonstrated that local tumor temperatures above 42°C damage cells substantially. Once MNP reach the tumor however, they interact with the local cell environment, binding to cell membranes and being internalized inside cells.
Wer sich beim Titel dieses Workshops mit Schrecken an so manches Seminar im Studium oder aber an das eine oder andere Team-Meeting der Projektgruppe erinnert fühlt, in der Gruppenarbeit auf „Mind-Maps“ reduziert und im Rahmen dessen eine Tafel ohne Struktur mit willkürlichen Begriffen vollgeschrieben wurde, ist hier genau richtig. Mittlerweile hat sich insbesondere in denjenigen Arbeitsbereichen, in denen Fachleute aus verschiedenen Disziplinen gemeinsam arbeiten, die Erkenntnis durchgesetzt, dass durch Kooperation zwar neue Ideen entwickelt werden können, auf die ein(e) Einzelne(r) allein wahrscheinlich nie gestoßen wäre. Gleichzeitig wächst aber auch die Einsicht, dass es nicht ausreicht, Mitarbeiter in einen Raum mit Kaffee und Keksen zu beordern und mit einer Leitfrage zu konfrontieren, um einen zielführenden Prozess in der Gruppe anzustoßen.
Die an Schule und Hochschule vermittelten Inhalte zu Gruppenarbeit und Gruppenarbeitsmethoden beschränken sich leider häufig auf die schlichte Nennung prägnanter Schlagworte wie „Brainstorming“ oder „Synergie“. Weitergehende Erläuterungen der hinter diesen Begriffen steckenden methodischen Herangehensweise oder gar Raum zum Austesten von Gruppenarbeitsmethoden werden Lehrenden und Studierenden häufig nicht gegeben.
Dadurch bleiben die Ergebnisse von Gruppenarbeit nicht nur hinter dem erreichbaren Potential der verwendeten Gruppenarbeitsmethoden zurück, ebenfalls sind gegenwärtig sowohl die Menge von vorhandenen Gruppenarbeitsmethoden als auch deren umfangreiche Spanne an möglichen Einsatzgebieten noch weitgehend unbekannt.
Sowohl für die medizinische Lehre als auch den späteren beruflichen Werdegang haben Begriffe wie „Zusammenarbeit“ und „Teamwork“ immer mehr an Bedeutung gewonnen. Die Teilnehmer lernen in diesem Workshop die Möglichkeiten und Grenzen von Gruppenarbeit und wie sie Lösungsstrategien auf Alltagsprobleme durch eine strukturierte Herangehensweise übertragen können. Dabei ist der Transfer sowohl in den studierendenzentrierten Kleingruppenunterricht, als auch in die gruppenorientierte Forschungstätigkeit möglich.
Schon mal darüber geärgert, dass einige Dozenten, Gruppenleiter oder Kollegen einfach nicht verständlich erklären können? Oder vielleicht sogar selber geflucht, weil einige der lieben Kollegen die Erklärungen, die man ihnen so ausführlich gegeben hat, einfach nicht verstehen (wollen)? Woran liegt es bloß, dass mündlich weitergegebene Informationen über Abläufe oft nicht im beabsichtigten Sinne praktisch umgesetzt werden?
Es ist nicht nur ärgerlich, wenn solche Erklärungen nicht wie gewünscht umgesetzt werden (können), es kann sogar richtig teuer und gar gefährlich werden. Aber wer trägt die Schuld daran: Die/Derjenige, der’s vielleicht unzureichend erklärt hat, oder die/derjenige, die/der die gegebenen Informationen nicht adäquat umsetzt? Oder beide?
Wer diese Schuldfrage ein für alle Mal geklärt haben will, komme bitte nicht zu diesem Workshop. Denn wir werden einige Erklärungsszenarien unter die Lupe nehmen, um uns konstruktiv mit der Frage auseinanderzusetzen, wie gutes Erklären ablaufen kann.
Conditional excess distribution modelling is a widely used technique, in financial and insurance mathematics or survival analysis, for instance. Classical theory considers the thresholds as fixed values. In contrast, the use of empirical quantiles as thresholds offers advantages with respect to the design of the statistical experiment. Either way, the modeller is in a non-standard situation and runs in the risk of improper usage of statistical procedures. From both points of view, statistical planning and inference, a detailed discussion is requested. For this purpose, we treat both methods and demonstrate the necessity taking into account the characteristics of the approaches in practice. In detail, we derive general statements for empirical processes related to the conditional excess distribution in both situations. As examples, estimating the mean excess and the conditional Value-at-Risk are given. We apply our findings for the testing problems of goodness-of-fit and homogeneity for the conditional excess distribution and obtain new results of outstanding interest.
Superparamagnetic nanoparticles (MNP) offer exciting applications for engineering and biomedicine in imaging, diagnostics, and therapy upon magnetic excitation. Specifically, if excited at two distinct frequencies f1 and f2, MNP responds with magnetic intermodulation frequencies m·f1 ± n·f2 caused by their nonlinear magnetization. These mixing frequencies are highly specific for MNP properties, uniquely characterizing their presence. In this review, the fundamentals of frequency mixing magnetic detection (FMMD) as a special case of magnetic particle spectroscopy (MPS) are reviewed, elaborating its functional principle that enables a large dynamic range of detection of MNP. Mathematical descriptions derived from Langevin modeling and micromagnetic Monte-Carlo simulations show matching predictions. The latest applications of FMMD in nanomaterials characterization as well as diagnostic and therapeutic biomedicine are highlighted: analysis of the phase of the FMMD signal characterizes the magnetic relaxation of MNP, allowing to determine hydrodynamic size and binding state. Variation of excitation amplitudes or magnetic offset fields enables determining the size distribution of the particles’ magnetic cores. This permits multiplex detection of polydisperse MNP in magnetic immunoassays, realized successfully for various biomolecular targets such as viruses, bacteria, proteins, and toxins. A portable magnetic reader enables portable immunodetection at point-of-care. Future applications toward theranostics are summarized and elaborated.
The aims of the present work was i. to investigate the acute effects of prolonged vibratory stimulation on short-latency stretch reflexes (SLR) of soleus muscle, ii. to assess effects of vibration on parameters of the H-reflex and M-wave stimulus-response curves. There were no changes in the EMG of SLR. During vibration H-reflex amplitudes decreased but H-reflex threshold current increased. None of the H-reflex parameters showed timedependent changes. In contrast, maximum M-wave magnitude (MMAX) decreased after 30min of sustained vibration. The analysis suggests differential effects of presynaptic inhibition on α-motoneurons. The vibration parameters have no effect on excitability of afferent and efferent fibers. The depression of the MMAX after vibratory stimulation may be related to neuromuscular transmission failure and/or reduced sarcolemmal excitability.
Astronauts exposed to microgravity experience physiological deconditioning, especially systems sensitive to force loading such as the musculoskeletal system. In order to attenuate these adverse effects, current ISS crew members perform a daily physical exercise countermeasure program, including treadmill running. However, the maximum vertical loading applied is usually not more than 70-80% of body weight (BW). As the triceps surae is one of the muscles most affected by immobilization but at the same time contributes significantly to vertical support and horizontal propulsion of the human body, it is important to examine the behaviour of its fascicles and tendon under unloading conditions to get a deeper understanding of what might cause the wasting and loss of function. Therefore, the aim of this study was to determine fascicle, tendon and muscle-tendon-unit (MTU) length of the gastrocnemius medialis muscle (GM) during running at 0.38g (Martian gravity), 0.7g (70% BW) and 1g.
Robotergestütztes System für ein verbessertes neuromuskuläres Aufbautraining der Beinstrecker
(2019)
Neuromuskuläres Aufbautraining der Beinstrecker ist ein wichtiger Bestandteil in der Rehabilitation und Prävention von Muskel-Skelett-Erkrankungen. Effektives Training erfordert hohe Muskelkräfte, die gleichzeitig hohe Belastungen von bereits geschädigten Strukturen bedeuten. Um trainingsinduzierte Schädigungen zu vermeiden, müssen diese Kräfte kontrolliert werden. Mit heutigen Trainingsgeräten können diese Ziele allerdings nicht erreicht werden. Für ein sicheres und effektives Training sollen durch den Einsatz der Robotik, Sensorik, eines Regelkreises sowie Muskel-Skelett-Modellen Belastungen am Zielgewebe direkt berechnet und kontrolliert werden. Auf Basis zweier Vorstudien zu möglichen Stellgrößen wird der Aufbau eines robotischen Systems vorgestellt, das sowohl für Forschungszwecke als auch zur Entwicklung neuartiger Trainingsgeräte verwendet werden kann.
Sehnen übernehmen im menschlichen Körper die Kraftübertragung zwischen Muskel und Knochen, als auch die Energiespeicherung und -freisetzung. Bisherige Studien zeigen, dass sich Sehnen entsprechend ihren Belastungen anpassen, d.h. Personen, die höhere Muskelkräfte generieren können, weisen in der Regel eine höhere Sehnensteifigkeit auf. Die Steifigkeit der Sehne ist im Wesentlichen durch ihren Querschnitt und ihre Materialeigenschaften determiniert.
High accelerations in the bobsleigh push phase are crucial for high bob velocities and therefore short final race times.For that, leg extensor muscles have to produce high mechanical power at the hip, knee, and ankle to propel the athlete’s body and the sled forward. In order to modify training and to enhance performance, the understanding of joint function is essential for coaches and athletes.
Vibration exposure, mostly applied as whole-body vibration, has been used more and more frequently in recent years in sports, health, research, preventive medicine and rehabilitation. It has been proven to be a useful training method and examination method in a variety of contexts. In the body, periodic stretching and shortening cycles of the muscle-tendon complex occur during vibration. This is accompanied by periodic changes in fascicle length (FL) and pennation angle (PEN). However, little is known about the extent to which stretching and shortening depends on muscular preload and frequency. Due to visco-elastic properties of the muscle, both factors should influence the stress-strain behavior in a speed-dependent manner. Therefore, the main aim of this study was to get an insight into vibration induced changes in FL and PEN at different frequencies and levels of preload. In addition, the influence of long-term bed rest on FL and PEN excursion is evaluated as well as the changes in static muscle architecture at different levels of contraction.
After complete Achilles tendon rupture (ATR), long-term deficits in force generation of the triceps surae muscle-tendon-unit (MTU) and functional limitations have been described. Surgical reconstruction and early functional treatment of Achilles tendon rupture can lead to a lengthened Achilles tendon causing a lack of tension in the triceps surae MTU. As a consequence, an excessive sarcomere overlap forces the muscle fascicles to operate in a disadvantage length for force generation. In order to restore function, we hypothesize that a re-organization of in-series sarcomeres may compensate for changes in work constraints imposed by the longer tendon. Tendon stiffness has already been described to increase after ATR, which might also be an actuator to compensate for tendon lengthening. To clarify the mentioned deficits, this study investigates the mechanical and morphological properties of the triceps surae MTU post rupture and their effect on force generation.
Leg- and joint stiffness in male elite high jump: the influence of stiffness on sports performance
(2017)
The purpose of this study was to analyse stiffness in the mechanical system of the world’s elite high jumpers. Seven male elite high jump athletes (personal best 2.24 m ± 0.06 m) were filmed with 19 Infrared-High-Speed-Cameras during jumping. Kinetics were captured with a force plate. It was found that a different leg and joint stiffness during takeoff enables nearly the same jumping height. For example, a typical power jumper with a leg stiffness of 543.6 N m-1 kg-1 reached 2.13 m, while a typical speed jumper with a leg stiffness of 1133.5 N m-1 kg-1 reached a comparable height of 2.12 m. Therefore, it seems that sports performance in single leg jumping is not limited by athlete’s leg and joint stiffness in a small group of male elite high jumpers.
Evaluation of passively induced shoulder stretch reflex using an isokinetic dynamometer in men
(2017)
The purpose of the current study was to determine shoulder internal rotator muscles' reflex latencies (SLR) under variable conditions in 20 healthy, specifically trained male participants. Sets of different external shoulder rotation stretches were applied via an isokinetic dynamometer. SLR latencies were determined from sEMG readings as the time from external shoulder rotation stretches application to onset of muscle activity. The amount of muscular response to the perturbation was evaluated via a peak-to-peak analysis. SLR latencies and amplitudes of the pectoral muscle and the anterior deltoid were affected by the investigated muscle and the level of pre-innervation torque. Our results indicated faster muscular stretch response than reported in previous studies which can be attributed to training induced adaptions of the shoulder muscles and capsule.
Changes in the kinematic and kinetic profile of handcycling propulsion due to increasing workloads
(2017)
The aim of this study was to examine changes in handcycling propulsion kinematics and kinetics due to increasing workloads. Twelve non-disabled male triathletes without handcycling experience performed a familiarisation protocol and an incremental step test in a recumbent racing handcycle that was attached to an ergometer. During the incremental test, the tangential crank kinetics, 3D joint kinematics, blood lactate and the rate of perceived exertion (local and global) were identified. The participants showed a significant increase in shoulder internal rotation and abduction and a decrease in elbow flexion and retroversion. Future studies should expand the test spectrum, consider the examination of muscle activation patterns (MAP) and replicate the study with elite handcyclists.
As water content is a determinant of the material properties of tendons and may affect sports performance and injury risk. The purpose of this pilot study was to evaluate the reliability and sensitivity of an MRI based method to quantify the hydration state of a tendon. For this study twenty porcine digital flexor tendons were utilized. All samples were examined on a MR scanner using three 3D ultra- short echo time sequences. With the applied sequences it was possible to determine a decrease in water content of the tendons. In addition, the methods showed good inter session reliability. Further investigations are needed to improve the upper and lower limit of resolution regarding the physiological hydration state.
Comparison of different training algorithms for the leg extension training with an industrial robot
(2018)
In the past, different training scenarios have been developed and implemented on robotic research platforms, but no systematic analysis and comparison have been done so far. This work deals with the comparison of an isokinematic (motion with constant velocity) and an isotonic (motion against constant weight) training algorithm. Both algorithms have been developed for a robotic research platform consisting of a 3D force plate and a high payload industrial robot, which allows leg extension training with arbitrary six-dimensional motion trajectories. In the isokinematic as well as the isotonic training algorithm, individual paths are defined in Cartesian space by sufficient support poses. In the isotonic training scenario the trajectory is adapted to the measured force as the robot should only move along the trajectory as long as the force applied by the user exceeds a minimum threshold. In the isotonic training scenario however, the robot's acceleration is a function of the force applied by the user. Since the robot is in direct interaction with the user, additional restrictions regarding the robot's velocity and acceleration have to be considered. To validate these findings, a simulative experime n t with a simple linear trajectory is performed. For this purpose, the same force path is applied in both training scenarios. The results illustrate that the algorithms differ in the force dependent t rajectory adaption. Future work will focus on the implementation of knee angle limitations and control of knee adduction moments during leg extension training.
Regular resistive exercise programs have proven meaningful for rehabilitation from injury and for counteracting the loss of muscle mass due to ageing or wealth related diseases. A particular challenge of resistive exercise programs is to apply the desired stress for the muscle but avoid overloading of the surrounding biological tissues such as tendons, ligaments and cartilage. External forces, movement velocity and range of motion are commonly used to control the intensity of resistive exercise programs. However, it is well known that those measures do not sufficiently represent the loading of joints and muscles. Therefore, the objective of the current project is to quantify and visualize internal joint loadings in real-time to control the intensity of resistive exercises. A common leg extension exercise (leg press) was implemented on a robotic research platform. The patient’s leg movements were recorded with a motion capture system. External forces and moments were recorded with a force plate (AMTI, USA) mounted to the robotic arm. Based on the recorded data, joint loadings were calculated and output in real-time using an individualized biomechanical musculoskeletal model and the inverse kinematics and dynamics algorithms provided by OpenSim (SimTK, USA). This approach enables a direct visual feedback in a virtual three dimensional environment using Unity (Unity Technolo-gies, USA) for both the patient and physiotherapist throughout the exercise. The visualized contributions of the hip-, knee- and ankle extensor muscles and the knee joint moment in the frontal plane as indicator for tibiofemoral joint loadings should support patients to execute the exercise correctly and thus, should improve safety and effectiveness of resistive exercise programs. Besides biofeedback, the developed tool can provide parameters for control applications in rehabilitation.
Hintergrund: Der Aufenthalt von Astronauten in Schwerelosigkeit führt zu einer Degeneration ihres muskuloskelettalen Systems. Um dies zu vermeiden, wird auf der internationalen Raumstation (ISS) täglich ein zweieinhalbstündiges Trainingsprogramm absolviert. Dieses beinhaltet unter anderem ein Laufbandtraining, wobei Belastungslevel von 70-80% des Körpergewichts (KG) meist nicht überschritten werden. Die Auswirkungen eines körpergewichtunterstützten Lauftrainings auf die Arbeitsweise der Plantarflexoren ist jedoch unklar. Da geringere Kräfte auf der Achillessehne lasten, wird vermutet, dass diese weniger stark gedehnt wird. Allerdings bleibt offen, welchen Einfluss eine kürzere Sehne auf die Muskelfaserbündellänge, den Fiederungswinkel sowie die Gesamtlänge der Muskel-Sehnen-Einheit (MSE) des M. gastrocnemius medialis (GM) nimmt. Dabei ist ein besseres Verständnis über die Arbeitsweise von Muskel und Sehne unter Teilbelastung unabdingbar für eine effektive Trainingsgestaltung.
Fragestellung: Welchen akuten Effekt hat ein Lauftraining auf dem vertikalen Laufband mit 70% (ISS) und 38% (Marsgravitation) im Vergleich zu 100% Körpergewicht auf die Achillessehnenlänge und wie beeinflusst dies die Arbeitsweise der Muskelfaserbündel und Muskel-Sehnen-Einheit des GM?
Methoden: 8 männliche Probanden (31.9 ± 4.7 Jahre) haben bei 70%, 38% und 100% KG ein Lauftraining auf einem vertikalen Laufband absolviert. Die Längenänderung der Muskelfaserbündel des GM während der Stützphase wurden anhand aufgezeichneter Ultraschallvideos bestimmt. Mittels Gelenkkinematik der unteren Extremitäten wurde die MSE Länge abgeschätzt und anschließend die Sehnenlänge mithilfe eines MSE-Models berechnet. Zur Analyse des Effekts der Teilbelastung wurde eine Varianzanalyse für abhängige Stichproben angewendet.
Ergebnisse: Körpergewichtunterstützes Lauftraining führt akut zu einer signifikant kürzeren maximale Sehnenlänge (P < 0.001). Im Vergleich zum Laufen mit 100% KG, ist bei 70% KG die maximale Sehnenlänge um 5.6 ± 3.7 mm (P < 0.001) und bei 38% KG um 11.2 ± 3.8 mm (P < 0.001) reduziert. Zum Zeitpunkt der maximalen Sehnenlänge ist bei Teilbelastung die MSE-Länge ebenfalls signifikant kürzer (P < 0.001) mit einem Längenunterschied von 1.8 ± 2 mm (P = 0.038) bei 70% KG und von 5.2 ± 2.5 mm (P = 0.002) bei 38% KG. Im Gegensatz dazu arbeiten die Muskelfaserbündel zum gleichen Zeitpunkt bei längerer Länge (P < 0.001) aber geringerem Fiederungswinkel (P = 0.002). Im Vergleich zu 100% KG, sind bei 70% und 38% KG die Faserbündel um 3.3 ± 1.9 mm (P = 0.4001) und 5.4 ± 1.5 mm (P < 0.001) länger aber 2.7 ± 2° (P = 0.014) und 3.7 ± 2.3° (P = 0.009) stumpfer im Winkel. Die Gesamtverkürzung der Faserbündel bleibt unverändert (P = 0.199).
This study examined the effect of walking with reduced external loading at mechanically equivalent speeds on muscle-tendon unit behaviour of the human gastrocnemius medialis with regard to rehabilitative gait training and exploration of partial gravity environments. The hypothesis was that gaitrelated tendon elongation would be lower with reduced external load. As secondary aims, it was determined, whether a shorter tendon is compensated for by a shorter muscle-tendon unit (due to different joint angles), longer fascicles and/or smaller pennation angle.
Muscle atrophy continues to be a problem in long duration missions in human spaceflight. Several studies in space and in human experimental bedrest have demonstrated that the medial gastrocnemius (GM) muscle is one of the most affected muscles, whilst the tibialis anterior (TA) muscle is spared from muscle wasting. To test countermeasures against this physiological deconditioning, NASA, ESA and the German Aerospace Center (DLR) are conducting the AGBRESA study. This is a 60-day head-down tilt bed rest study that assess the effectiveness of two different protocols of human centrifugation (artificial gravity) as countermeasure for spaceflight. We have recently become interested in intramuscular connective tissue and passive elastic properties of skeletal muscle. One approach to assess tissue elastic properties is by shear wave elastography.
Hintergrund: Regelmäßiges körperliches Widerstandstraining bietet ein hohes Potential in der Prävention und Therapie von Verletzungen und wirkt dem Verlust von Muskelmasse aufgrund von Alter oder Wohlstandskrankheiten entgegen. Eine spezielle Herausfordung ist es dabei, den gewünschten und erforderlichen Reiz für die Muskeln zu setzen und gleichzeitig Überlastungen des umgebenden Weichgewebes, wie zum Beispiel Sehnen, Bänder und Knorpel, zu vermeiden. Meist werden dabei die am Gerät aufgelegten Gewichte, bzw. die äußeren Kräfte, die Bewegungsgeschwindigkeit und der Bewegungsumfang zur Kontrolle der Intensität des Widerstandtrainings genutzt. Allerdings ist bekannt, dass diese Parameter nur den äußeren Zustand beschreiben, die interne Belastung der Muskeln und Gelenke aber nicht ausreichend wiedergeben und beschreiben.
Fragestellung: Deshalb ist das Ziel dieses Projekts, die innere Belastung in den Gelenken während des Widerstandstrainings online zu quantifizieren und zu visualisieren, um die Intensität kontrollieren und steuern zu können.
Methode: Eine häufig angewendete Beinextensionsübung (Beinpresse bzw. Funktionsstemme) wurde in einer robotischen Entwicklungsumgebung implementiert. Die Bewegung des Patienten wird mit einem Motion Tracking System aufgenommen. Die äußeren Kräfte und Momente werden mit einer Kraftmessplatte (AMTI, USA), die am Endeffektor des Roboterarms montiert ist, gemessen. Auf Grundlage der aufgenommenen Daten werden direkt während des Trainings die Gelenkbelastungen berechnet und ausgegeben. Die Berechnung erfolgt mit einem auf den Patienten individualisierten biomechanischen muskuloskelettalen Modell und der von OpenSim (SimTK, USA) bereitgestellten Algorithmen für die inverse Kinematik und inverse Dynamik.
Ergebnisse & Schlussfolgerung: Dieses Vorgehen ermöglicht ein direktes visuelles Feedback während des Trainings in einer mit Unity (Unity Technologies, USA) erstellten virtuellen dreidimensionalen Umgebung für den Patienten und auch für den Physiotherapeuten. Die visualisierten Anteile der Hüft-, Knie- und Sprunggelenkextensoren und das Kniegelenkmoment in der Frontalebene dienen als Indikatoren für die tibiofemorale Gelenkbelastung. Sie ünterstützen den Patienten dabei, die Übung korrekt auszuführen und sollen die Sicherheit und die Effektivität des Widerstandstrainingsprogramms erhöhen.Weiterhin werden Gelenkwinkel und Gelenkmomente in der Sagittalebene quantitativ sichtbar. Zudem ermöglichen die ausgegebenen Parameter dem Therapeuten die Beobachtung des inneren Belastungszustand des Patienten für eine sofortige Intervention als auch für eine individualiserte Planung des neuromuskulären Widerstandstraining. Neben des Biofeedbacks kann das entwickelte Tool auch Parameter für Regelungtechnische Anwendungen in der Rehabilitation liefern.
Die mit der Alterung verbundenen Pflegekosten, der demographische Wandel und der Pflegenotstand sind Aspekte von höchster gesellschaftlicher Relevanz, die zahlreiche rechtliche, ethische, soziale und ökonomische Fragen aufwerfen. Im Zuge der Alterungsvorgänge kommt es zum Verlust der körperlichen und kognitiven Leistungsfähigkeiten. Regelmäßiges körperliches Training kann diesen degenerativen Prozess verlangsamen und damit die Entstehung chronischer Erkrankungen vermeiden bzw. verzögern. Darüber hinaus kann physische Aktivität das subjektive Wohlbefinden positiv beeinflussen. Effektives körperliches Training führt allerdings zu zusätzlichen Belastungen für den menschlichen Körper, die unkontrolliert zu Überbelastungen und Schädigungen des Bewegungsapparates führen können. Zur Vermeidung dieser nicht physiologisch angepassten Belastung ist die Kontrolle der Belastung des Muskel-Skelett-Systems sowie des Herz-Kreislaufsystems zwingend erforderlich.
Im Rahmen dieses Vorhabens wurden daher Robotersysteme dazu befähigt, mit einem Menschen unter Aufbringung signifikanter Kräfte aktiv und sicher interagieren zu können. Die Interaktion von Menschen und Robotern ist eine komplex zu realisierende Fähigkeit, die sich aus mehreren Grundfertigkeiten zusammensetzt. Eine robuste und sichere Realisierung dieser Grundfertigkeiten eröffnet ein breites Spektrum an neuen Aufgabenstellungen und Applikationsszenarien außerhalb des klassischen industriellen Sektors. Um die Übertragbarkeit der Grundfertigkeiten aufzuzeigen, wurden drei unterschiedliche, sich gegenseitig ergänzende Systeme aus dem gesellschaftlich sehr relevanten Bereich der Rehabilitation (Muskelaufbau und Muskelkoordination) betrachtet, und mit denselben Grundfertigkeiten ausgestattet.
Mit dem stationären System werden zunächst grundlegende neuromuskuläre Kapazitäten unter kontrollierten Bedingungen aufgebaut. Das mobile System unterstützt den älteren Menschen dabei, die durch das Krafttraining erworbenen neuromuskulären Kapazitäten in verbesserte Bewegungsfertigkeiten umzusetzen, d. h. z. B. zur Erhöhung der Stabilität beim Gehen und Stehen sowie zu einer besseren Bewegungsausführung bei der Fortbewegung, um die Belastung der Gelenke zu reduzieren. Weiterhin kann das System mit Manipulator als Assistenzsystem im Alltag den Nutzer unterstützen, um zum Beispiel durch das gemeinsame Handhaben von Gegenständen ein selbständigeres Leben zu ermöglichen.
Sarcolab-3: Changes in knee and ankle torque generation during a six-month space flight mission
(2021)
Hintergrund: Eine auf der Intensivstation (ITS) erworbene Muskelschwäche ist eine häufig auftretende Komplikation, welche mit einer erhöhten Morbidität, einer Verzögerung der Rehabilitation und einer lang anhaltenden Einschränkung der Aktivitäten des täglichen Lebens assoziiert wird. Hinsichtlich der aktuellen COVID-19-Pandemie, war das Ziel dieser Arbeit herauszufinden, wie sich die kardiovaskuläre und muskuläre Leistungsfähigkeit von kritisch kranken Patient*innen auf einer Intensivstation gestaltet und ob sich die Leistungsfähigkeit vom Tag des Erwachens bis zum Tag der ITS-Entlassung verändert, gemessen an standardisierten Testverfahren.
Methodik: Es wurde eine systematische Literaturrecherche anhand der Datenbanken PubMed und Cochrane Library durchgeführt. Sechs Studien wurden in die qualitative Zusammenfassung eingeschlossen und schließlich voll analysiert. Die Auswertung der Daten erfolgte anhand fünf international anerkannter Testverfahren: (1) Medical Research Council Sumscore (Muskelkrafttest), (2) Handkrafttest, (3) Gesundheitsfragebogen SF-36, (4) 6-Minuten-Gehtest und (5) Timed-Up-And-Go-Test.
Ergebnisse: In dieser Arbeit werden die Ergebnisse der sechs Studien auf den Zeitpunkt des Erwachens und auf den Zeitpunkt des Verlassens der Intensivstation beschränkt. Nur eine Studie beschrieb signifikante Unterschiede bezüglich der Muskel- und Handkraft. Alle anderen Studien konnten keine Signifikanzen feststellen.
Schlussfolgerung: Aufgrund der geringen Studienlage kann zum jetzigen Zeitpunkt noch keine klare Aussage über den kardiovaskulären und muskulären Zustand von Intensivpatienten getroffen werden. Es müssen mehr Studien mit einem einheitlichen Protokoll und vergleichbaren Testverfahren durchgeführt werden, um die Fragestellung deutlich beantworten zu können.
Background
Astronauts have a higher risk of cervical intervertebral disc herniation. Several mechanisms have been attributed as causative factors for this increased risk. However, most of the previous studies have examined potential causal factors for lumbar intervertebral disc herniation only. Hence, we aim to conduct a study to identify the various changes in the cervical spine that lead to an increased risk of cervical disc herniation after spaceflight.
Methods
A cohort study with astronauts will be conducted. The data collection will involve four main components: a) Magnetic resonance imaging (MRI); b) cervical 3D kinematics; c) an Integrated Protocol consisting of maximal and submaximal voluntary contractions of the neck muscles, endurance testing of the neck muscles, neck muscle fatigue testing and questionnaires; and d) dual energy X-ray absorptiometry (DXA) examination. Measurements will be conducted at several time points before and after astronauts visit the International Space Station. The main outcomes of interest are adaptations in the cervical discs, muscles and bones.
Discussion
Astronauts are at higher risk of cervical disc herniation, but contributing factors remain unclear. The results of this study will inform future preventive measures for astronauts and will also contribute to the understanding of intervertebral disc herniation risk in the cervical spine for people on Earth. In addition, we anticipate deeper insight into the aetiology of neck pain with this research project.
Kampfpiloten sind in Abhängigkeit vom Luftfahrzeugmuster und ihrem jeweiligen fliegerischen Auftrag Beschleunigungen im Bereich des 5- bis 9-fachen der Erdbeschleunigung ausgesetzt. Das uneingeschränkte Bewegungsvermögen der Halswirbelsäule auch unter hoher G-Belastung ist essenziell für die visuelle Beobachtung des umgebenden Luftraums und somit für den Einsatzwert. Der Hals- und Nackenbereich gilt als vulnerable Region, da es kein protektives Entlastungs- oder Schutzsystem (z.B. Anti-G-Suite, Helm) für die HWS gibt.
Physiotherapeut*innen benötigen spezifische Kompetenzen, um die Chancen fortschreitender Digitalisierung zu integrieren. Empfehlungen für entsprechende Kompetenzen bestehen z.B. für Pflege und Medizin, jedoch nach aktuellem Kenntnisstand nicht für Physiotherapeut*innen. Eine übergeordnete Lernzielliste mit informatikbezogenen Kompetenzen für Angehörige von Gesundheitsfachberufen existiert bereits (HITCOMP; http://hitcomp.org/about ). Im Rahmen dieses Projektes wurde diese Liste für ein Konsentierungsverfahren angepasst und ein Studienprotokoll für eine Delphi Studie erstellt. Die Lernziele wurden übersetzt, Kompetenzniveaus zugeordnet und in sieben Domänen (Allgemeine Kenntnisse, Dokumentation, Arbeitsabläufe und Entscheidungshilfen, Kommunikation und Koordination, Datenschutz und Qualitätsmanagement, Patient Empowerment und sekundäre Datennutzung) gegliedert. Formulierungen wurden auf den Anwendungsbereich Physiotherapie angepasst. Somit existiert ein vorläufiger Lernzielkatalog mit 64 Lernzielen. Für das Studienprotokoll wurden Empfehlungen zur Berichterstattung von Delphi-Verfahren genutzt (Spranger et al, 2022). Ein zweischrittiges Verfahren mit Ergebnisrückmeldung der ersten Befragungsrunde ist geplant. Einschlusskriterien für Teilnehmer*innen umfassen eine abgeschlossene Physiotherapie-Ausbildung, Expertise im Bereich der Lehre oder Forschung und Auseinandersetzung mit dem Themengebiet informatischer Inhalte. Als Befragungsinstrumente dienen ein digitaler Fragebogen und das im Rahmen der Medizininformatik-Initiative etablierte webbasierte Tool Health Informatics Learning Objective Navigator (HI-LONa) (Spreckelsen et al., 2021). Als zentraler Aspekt soll die Relevanz jedes Lernziels anhand einer fünfstufigen Skala eingeschätzt werden. Nach der zweiten Befragungsrunde werden Lernziele mit einer Median- Relevanzbewertung größer gleich vier in den resultierenden Lernzielkatalog aufgenommen.
Erstmalig wurden informatikbezogene Kompetenzen für Physiotherapeut*innen auf Bachelorniveau in einem Lernzielkatalog zusammengetragen und ein Studienprotokoll für deren Konsentierung vorbereitet. Die Durchführung der Studie und Schritte zur Implementierung informatikbezogener Kompetenzen in die physiotherapeutische Ausbildung werden Gegenstand nachfolgender Forschung sein.
Eine Erkrankung, die weltweit hohe Inzidenzen aufweist, sind chronifizierte Nackenschmerzen. Neben einer Verminderung der Lebensqualität, sind sie eine der Hauptursachen für Arbeitsunfähigkeit. Ein vielversprechender Behandlungsansatz könnte die Therapie mit Virtual Reality (VR) sein: Übersichtsarbeiten konnten bereits positive Effekte auf chronische Schmerzen (Wong et al., 2022) oder Nackenschmerzen (Gumaa et al., 2021; Guo et al., 2023) nachweisen. Es wurde jedoch nicht zwischen akuten und chronischen Nackenschmerzen unterschieden Die vorliegende Metaanalyse hat das Ziel, den Effekt einer nicht immersiven und einer vergleichbaren immersiven VR-Therapie auf Patient*innen mit chronischen Nackenschmerzen (mind. 3 Monate) zu untersuchen.
Introduction: Power loss of skeletal muscles remains a major negative side effect of longterm exposure to weightlessness. Besides muscle atrophy also changes in muscle architecture and mechanics have significant force reducing impact. In muscle research it is well established to analyse changes in fascicle’s length and pennation angle. Several studies reported that fascicles sometimes curve. This bending could be another mechanical parameter that influences the muscle’s force generation. It has been shown that muscle fascicle curvature increases with increasing contraction level (CL) and decreasing muscle-tendon-complex (MTC) length. The analyses in these studies were done with limited examination windows concerning contraction state, MTC length and/or intramuscular position of ultrasound imaging. Additionally, fascicle curving has, to the best of our knowledge, not yet been produced by in-silico muscle models, which suggests that the mechanisms are poorly understood. With this study we aimed to investigate the phenomenon of fascicle arching in gastrocnemius muscles in order to develop hypotheses about its fundamental mechanism and to reproduce the curving with a theoretical mesh-type muscle model.
Integrative biomechanics of a human–robot carrying task : implications for future collaborative work
(2025)
Patients with sarcopenia, who face difficulties in carrying heavy loads, may benefit from collaborative robotic assistance that is modeled after human–human interaction. The objective of this study is to describe the kinematics and spatio-temporal parameters during a collaborative carrying task involving both human and robotic partners. Fourteen subjects carried a table while moving forward with a human and a robotic partner. The movements were recorded using a three-dimensional motion capture system. The subjects successfully completed the task of carrying the table with the robot. No significant differences were found in the shoulder and elbow flexion/extension angles. In human–human dyads, the center of mass naturally oscillated vertically with an amplitude of approximately 2 cm. The here presented results of the human–human interaction serve as a model for the development of future robotic systems, designed for collaborative manipulation.
INTRODUCTION: Microgravity is known to have a detrimental effect on the human musculoskeletal (MSK) system. Although various countermeasures have been tested during missions, most astronauts still suffer from muscle wasting and bone loss on their return to Earth (e.g. Demontis et al. 2017). In the future, astronauts will locomote once settled on Moon or Mars, but little is known about the load of daily locomotion in such environments and the potential effect on the MSK system. The aim of this study was to calculate external and internal load during different gaits in emulated Moon and Mars gravity levels.
METHODS: Hypogravity levels were emulated with a body weight suspension system in the L.O.O.P. facility (Herssens et al. 2022). Three participants were asked to walk at 1.39 m/s, and run and skip at 1.39, 1.94 and 2.50 m/s on an instrumented treadmill at Earth, Mars and Moon gravity levels while motion capture system recorded the position of 66 markers. Joint angles and net joint moments were calculated using inverse kinematics and dynamics, respectively, in OpenSim.
RESULTS: Ground reaction forces peaks were speed and gravity dependent in all gaits. Running showed the highest vertical average peak at 1.39 and 1.94 m/s in hypogravity (~1.5 BW). At 2.50 m/s, running showed highest peaks on Mars (~1.6 BW), whereas skipping and running shared the same peaks on Moon (~1.2 BW). Joint moments were gait, speed and gravity dependent at the hip and knee. Peak joint moments increased with speed and decreased with hypogravity for all gaits but showed higher values in the trailing leg during skipping compared to walking and running at all gravities and speeds. At the ankle, skipping and running showed similar values at both hypogravity levels (1-1.4 N*m*kg-1), which were lower than Earth, with highest values observed for running on Earth compared to the other two gaits. Ground reaction force and joint moment values are higher in locomotion compared with submaximal single leg hopping (Cowburn et al. 2024), a promising countermeasure.
CONCLUSION: We have estimated, for the first time, the external and internal load during locomotion at different hypogravity levels. Such information is key to devise exercise programmes in the future to be used by astronauts as countermeasures. External and internal load showed different trends when gait-speed-gravity level were compared, with running generating the highest external load and skipping the highest internal one.
Since Yuri Gagarin’s pioneering flight in 1961, numerous missions of varying length and on a range of platforms have explored space and its effects on the human body. To maximize the benefits of future Mars and moon missions, extravehicular activities in low-gravity environments will be essential during human exploration. In sustained missions (Artemis 2), crewmembers are required to move from a defective rover to a safe location over distances of up to 12 km. A simple fall due to muscle weakness or lack of locomotor control could result in injuries or spacesuit damage that could be lifethreatening. Ultrasonic visualization of muscle fascicle and tendon (SEE) behavior during locomotion has demonstrated the importance of the storage and release of elastic energy by the Achilles tendon in running and walking, and that the plantar flexor muscles modulate their behavior depending on gait type, speed, and external loading. Despite the relevance of this topic to both space travel and rehabilitation, only a few studies have examined the behavior of muscles and tendons in simulated or real hypergravity. The shorter peak SEE length observed during running in simulated 0.7 g may be the result of lower muscular forces acting on the SEE (Richter et al., 2021a). The longer fascicles observed during running in simulated (0.7 g) hypogravity may result in an increased strain on the z-disks, which in turn may be beneficial for muscle mass preservation. Decreasing g-level from 1 g to simulated Martian and lunar gravity resulted in hypogravity-induced alterations in SEE length, and contractile behavior that persisted between simulated running on the moon and Mars (Richter et al., 2021b). This should be taken into account when evaluating exercise prescriptions and the transferability of locomotion practiced in lunar gravity to Martian gravity. Monti et al. (2021) assessed fascicle behavior during the locomotorlike task—drop jump—during a parabolic flight. Upon landing, gastrocnemius medialis fascicles showed lengthening in all gravity levels below and above 1 g and quasi-isometric fascicle behavior in 1 g. Such behavior was potentially due to the lower level of muscle pre-activation (Waldvogel et al., 2021), implying a modulation of the muscle’s mode of operation toward a damping function. Thus, existing studies have demonstrated that the consequences of locomotion in hypogravity are not limited to a mere reduction in mechanical loading but also to an altered contractile behavior, which could affect the muscle’s work capacity upon return to daily activities in a 1 g environment and may require specific attention for adequate countermeasures and during the rehabilitation phase.
This study investigates the morphological, mechanical, and viscoelastic properties of bacterial cellulose (BC) hydrogels synthesized by the microbial consortium Medusomyces gisevii. BC gel films were produced under static (S) or bioreactor (BioR) conditions. Additionally, an anisotropic sandwich-like composite BC film was developed and tested, consisting of a rehydrated (S-RDH) BC film synthesized under static conditions, placed between two BioR-derived BC layers. Sample characterization was performed using scanning electron microscopy (SEM), atomic force microscopy (AFM), rheometry, and uniaxial stretching tests. To our knowledge, this is the first study to combine uniaxial and rheological tests for BC gels. AFM and SEM revealed that the organization of BC fibrils (80±20 nm in diameter) was similar to that of collagen fibers (96±31 nm) found in human dura mater, suggesting potential implications for neurosurgical practice. Stretching tests demonstrated that the drying and rehydration of BC films resulted in a 2- to 8-fold increase in rigidity compared to other samples. This trend was consistent across both small and large deformations, regardless of direction. Mechanically, the composite (BioR+S-RDH) outperformed BC hydrogels synthesized under static and bioreactor conditions by approx. 26%. The composite material (BioR+S-RDH) exhibited greater anisotropy in the stretching tests compared to S-RDH, but less than the BioR-derived hydrogels, which had anisotropy coefficients ranging from 1.29 to 2.03. BioR+S-RDH also demonstrated the most consistent viscoelastic behavior, indicating its suitability for withstanding shear stress and potential use in prosthetic applications. These findings should provide opportunities for further research and medical applications.
FUSION: Feature-based Processing of Heterogeneous Documents for Automated Information Extraction
(2022)
Information Extraction (IE) processes are often business-critical, but very hard to automate due to a heterogeneous data basis. Specific document characteristics, also called features, influence the optimal way of processing. Architecture for Automated Generation of Distributed Information Extraction Pipelines (ARTIFACT) supports businesses in successively automating their IE processes by finding optimal IE pipelines. However, ARTIFACT treats each document the same way, and does not enable document-specific processing. Single solution strategies can perform extraordinarily well for documents with particular traits. While manual approvals are superfluous for these documents, ARTIFACT does not provide the opportunity for Fully Automatic Processing (FAP). Therefore, we introduce an enhanced pattern that integrates an extensible and domain-independent concept of feature detection based on microservices. Due to this, we create two fundamental benefits. First, the document-specific process ing increases the quality of automated generated IE pipelines. Second, the system enables FAP to eliminate superfluous approval efforts.
Comparative performance analysis of active learning strategies for the entity recognition task
(2024)
Supervised learning requires a lot of annotated data, which makes the annotation process time-consuming and expensive. Active Learning (AL) offers a promising solution by reducing the number of labeled data needed while maintaining model performance. This work focuses on the application of supervised learning and AL for (named) entity recognition, which is a subdiscipline of Natural Language Processing (NLP). Despite the potential of AL in this area, there is still a limited understanding of the performance of different approaches. We address this gap by conducting a comparative performance analysis with diverse, carefully selected corpora and AL strategies. Thereby, we establish a standardized evaluation setting to ensure reproducibility and consistency across experiments. With our analysis, we discover scenarios where AL provides performance improvements and others where its benefits are limited. In particular, we find that strategies including historical information from the learn ing process and maximizing entity information yield the most significant improvements. Our findings can guide researchers and practitioners in optimizing their annotation efforts.
We generalize the projection correlation idea for testing independence of random vectors which is known as a powerful method in multivariate analysis. A universal Hilbert space approach makes the new testing procedures useful in various cases and ensures the applicability to high or even infinite dimensional data. We prove that the new tests keep the significance level under the null hypothesis of independence exactly and can detect any alternative of dependence in the limit, in particular in settings where the dimensions of the observations is infinite or tend to infinity simultaneously with the sample size. Simulations demonstrate that the generalization does not impair the good performance of the approach and confirm our theoretical findings. Furthermore, we describe the implementation of the new approach and present a real data example for illustration.
Industrial digestates from short-fibre residues, generated in paper recycling mills, are driving interest in resource recovery. This study aims to explore their potential for water recovery. Understanding particle dynamics aids in optimizing dewatering for digestate management. The particle size distribution in this study revealed significant fractions: <0.63 μm (6–20%), 0.63–20 μm (38–52%), and >20 μm (11–16%). Pre-treatment with Na4P2O7 and H2O2 enhances settling and lowers total dissolved solids (TDSs) but results in variation of size distribution. Additionally, this study investigates further water reuse in paper mills, focusing on the quality of ultrafiltration (UF) permeate obtained from the digestate of short fibres. UF permeate analysis reveals deviations from freshwater standards in paper mills. Despite effective TS removal, UF permeate falls short of paper mill water standards due to high TDSs, electrical conductivity, and nutrient concentrations, necessitating further downstream treatment with nanofiltration or reverse osmosis. A substantial reduction of permeate flux from 31 to 5 L/(m2·h) over the time indicated fouling and inefficient membrane wash. The silt density index of the UF membrane at 30 min registered 2.1, suggesting potential fouling. Further investigations on optimizing UF operations to enhance permeate flux and exploring alternative UF membranes are required.
There is significant interest in sampling subglacial environments for geochemical and microbiological studies, yet those environments are typically difficult to access. Existing ice-drilling technologies make it cumbersome to maintain microbiologically clean access for sample acquisition and environmental stewardship of potentially fragile subglacial aquatic ecosystems. With the "IceMole", a minimally invasive, maneuverable subsurface ice probe, we have developed a clean glacial exploration technology for in-situ analysis and sampling of glacial ice and sub- and englacial materials. Its design is based on combining melting and mechanical stabilization, using an ice screw at the tip of the melting head to maintain firm contact between the melting head and the ice. The IceMole can change its melting direction by differential heating of the melting head and optional side wall heaters. Downward, horizontal and upward melting, as well as curve driving and penetration of particulate-ladden layers has already been demonstrated in several field tests. This maneuverability of the IceMole also necessitates a sophisticated on-board navigation system, capable of autonomous operations. Therefore, between 2012 and 2014, a more advanced probe was developed as part of the "Enceladus Explorer" (EnEx) project. The EnEx-IceMole offers systems for accurate positioning, based on in-ice attitude determination, acoustic positioning, ultrasonic obstacle and target detection, which is all integrated through a high-level sensor fusion algorithm. In December 2014, the EnEx-IceMole was used for clean access into a unique subglacial aquatic environment at Blood Falls, Antarctica, where an englacial brine sample was successfully obtained after about 17 meters of oblique melting. Particular attention was paid to clean protocols for sampling for geochemical and microbiological analysis. In this contribution, we will describe the general technological approach of the IceMole and report on the results of its deployment at Blood Falls. In contrast to conventional melting-probe applications, which can only melt vertically, the IceMole realized an oblique melting path to penetrate the englacial conduit. Experimental and numerical results on melting at oblique angles are rare. Besides reporting on the IceMole technology and the field deployment itself, we will compare and discuss the observed melting behavior with re-analysis results in the context of a recently developed numerical model. Finally, we will present our first steps in utilizing the model to infer on the ambient cryo-environment.
Magnetic nanoparticles (MNP) are widely investigated for biomedical applications in diagnostics (e.g. imaging), therapeutics (e.g. hyperthermia) and general biosensing. For all these applications, the MNPs’ unique magnetic relaxation mechanism in an alternating magnetic field (AFM) is stimulated to induce desired effects. Whereas magnetic fluid hyperthermia (MFH) and magnetic particle imaging (MPI) are the most prominent examples for biomedical application, we investigate the relatively new biosensing application of frequency mixing magnetic detection (FMMD) from a fundamental perspective. Generally, we ask how specific MNP parameters (core size, magnetic anisotropy) influence the signal, specifically we predict the most effective MNP core size for signal generation. In FMMD, simultaneously two AFM are applied: a low-frequency magnetic driving field, driving MNP close to saturation, and a high-frequency excitation field that probes MNP susceptibility: . Resulting from the nonlinear magnetization of the MNP, harmonics of both individual incident frequencies as well as intermodulation products of these frequencies are generated. In this work, we present numerical Monte-Carlo(MC)-based simulations of the MNP relaxation process, solving the Landau-Lifshitz-Gilbert (LLG) equation to predict FMMD signals: As Figure 1 shows for the first four intermodulation signals , with , we can clearly see that larger core sizes generally increase the signal intensity. Same trend is predicted by a simple Langevin-function based thermal equilibrium model. Both predictions include a lognormal size distribution. The effect of core size distribution presumably dominates the effect of magnetic anisotropy. The findings are supported by comparison with experimental data and help to identify which MNP are best suited for magnetic biosensing applications using FMMD.
Frequency mixing magneticdetection(FMMD) has been widely utilized as a measurement technique in magnetic immunoassays. It can also be used for characterization[1]and distinction[2](also known as “colorization”) ofdifferent types of magnetic nanoparticlesaccording totheircore sizes.It is well known that the large particles contribute most of the FMMD signal. Typically, 90% of the signal stems from the largest 10% of the particles [1]. This leads to ambiguities in core size fitting since thecontribution of thesmall sized particles is almostundetectable among the strong responses from the large ones. In this work, we report on how this ambiguity can be overcome. Magnetic nanoparticle samples from Micromod (Rostock, Germany) were prepared in liquid and filterbound state. Their FMMD response at mixing frequencies f1 ± nf2 to magnetic excitation H(t)=H0+H1sin(2 f1t)+H2sin(2 f2t),with H1=1.3mT/μ0 at f1=40.5kHzandH2=16mT/μ0 at f2=63Hz,was measured as a function ofoffset field strength H0= (0,…,24) mT/μ0.The signal calculated fromLangevin model in thermodynamic equilibrium[1]with a lognormal core size distribution fL(dc,d0, ,A) = Aexp(–ln²(dc/d0)/(2 ²))/(dc (2 )1/2)was fitted to the experimental data. For each choice of median diameter d0, pairs of parameters ( ,A) are found which yield excellent fit results with R²>0.99.All the lognormal core size distributions shown in Figure (a) are compatible with the measurements because their large-size tails are almost equal. However, all distributions have different number of particles and different total iron content. We determined the samples’ total iron mass with inductively coupled plasma optical emission spectrometry(ICP-OES) and, out of all possible lognormal distributions, determined the one with the same amount of iron. With this additional externally measured parameter, we resolved the ambiguity in core size distribution and determined the parameters (d0, ,A).
Hyperthermia with the use of magnetic nanoparticles (MNP) is a challenging but most promising approach for cancer therapy. After being magnetically trapped at the tumor site, MNP are heated in alternating magnetic fields (AMF) to approx. 43 °C, which causes tumor cell apoptosis. For an effective and controllable hyperthermia application, two parameters are most important: the amount of internalized MNP in tumor cells and their heating characteristics in AMF. In this study, we evaluated if a sufficient temperature could be achieved by cell internalized MNP heated up in AMF and if cell death could be induced in this way. The heating of pancreatic tumor cell lines MiaPaCa-2 and BxPC-3 loaded with different amounts of selfsynthesized magnetoliposomes nanoparticles (MLs) was measured with a custom-built setup. The MLs consisted of a fluorescent bi-layer of phospholipids and multiple magnetite (Fe3O4) cores with a diameter of (10.0 ± 0.5) nm each. The hydrodynamic diameter of the MLs was (90 ± 5) nm. Cell loading was performed by incubation of tumor cells for up to 24 h at 37 °C in a DMEM cell medium with MLs, which had an iron concentration of 150 μg/mL. Transmission electron microscopy and fluorescence microscopy were used to depict the uptake of MLs into the tumor cells (see Figure). The internalized iron-content per cell was determined with a magnetic particle spectrometer (MPS). After application of AMF for approx. 30 min, cell viability was assessed by clonogenic assay. The cellular uptake of MLs was time-dependent, cell line-specific and saturated: For both MiaPaCa-2 and BxPC-3 cell lines, the MLs cell internalization followed an exponential growth function which saturated after about 24 h cell incubation time at an iron load of (110 ± 6) pg/cell and (30 ± 2) pg/cell, respectively. The time constants of the exponential growth were (7.2 ± 1.4) h and (4.0 ± 0.6) h, respectively. In AMF, cells with the saturated MLs loading reached temperatures of approx. 44 °C and 43.5 °C, which caused the cell survival fraction to drop to approx. one third compared to untreated tumor cells for both MiaPaCa-2 and BxPC-3 cell lines. These results demonstrate the feasibility of hyperthermia in pancreatic cancer treatment by confirming cell death of pancreatic tumor cells at temperatures of approx. 43 °C. Further investigations are planned, which aim for the optimization of MNP dosage in targeting experiments as well as the assessment of incubation times and AMF parameters needed for a successful hyperthermic therapy.
In the innovative tumor treatment approach of magnetic fluid hyperthermia (MFH), magnetic nanoparticles (MNP) are accumulated at the tumor site and heated in a time-varying magnetic field to substantially damage the tumor (1). This tumor damage depends mainly on the rate and amount of heat delivered via the MNP locally, which is in turn governed by a multitude of variables including the applied field amplitude and frequency, particle size and size distribution. In this study, we compare measured heating rates of MNP with sizes ranging from 21 nm to 28 nm with those obtained from Monte Carlo simulations of non-equilibrium Langevin dynamics to predict particle sizes and field amplitude /frequency settings for optimized MFH within medically safe tolerances. We have synthesized monodisperse iron-oxide MNP via thermal decomposition, coated with poly(ethylene glycol) methyl ether amine (mPEG NH2) as reported in (2). Transmission electron microscopy analysis yielded core sizes (and log-normal distribution width) of 21.9 nm (0.04), 23.1 nm (0.05), 25.3 nm (0.08) and 27.7 nm (0.07). These MNP were subjected to magnetic fields with amplitudes h0 = (6...20) mT/ 0-1 and frequencies f = (176...993) kHz in a magneTherm hyperthermia device (nanoTherics Ltd., Newcastle under Lyme, UK). From the recorded timetemperature curves we calculated the specific loss power (SLP) as a measure of the heating rate: SLP values increased generally with size and frequency (Fig. 1a), as well as with the field amplitude (not shown here). Monte Carlo based stochastic Langevin equation simulations combining Néel and Brownian rotation relaxation and thermal activation (based on (3)) verified this trend (Fig. 1b). Under the assumption of an upper field limitation of f[kHz] · h0[mT/ 0-1] 1758 imposed by medical safety requirements (4), we simulated a heat map based on the parameters obtained from fitting simulation to experiment (Fig. 1c). This map shows maximum SLP values for frequencies f ~ 100 kHz (equivalent to h0 ~ 17.5 mT/ 0-1) at particle sizes of 29 nm and greater. These results can provide a pivotal and integral tool for predicting particle sizes and applied field settings for optimized MFH.
The heat generated by magnetic nanoparticles (MNP) forms the basis of magnetic fluid hyperthermia (MFH) tumor therapy and arises from MNP magnetic moments relaxing in an alternating magnetic field. In physiological environments MNP strongly interact with cells, binding to their membranes as well as internalizing inside lysosomes, which alters the MNP magnetic relaxation. In the present study, we investigate the heating behavior of MNP in-vitro for different binding states and compare it to the heating of trapped MNP in dedicated hydrogels of different mesh size, mimicking different immobilization states. We used iron-oxide MNP (mean core size 10 nm) with a biocompatible phospholipid coating, referred to as magnetoliposomes (ML), for in-vitro studies, and with citric acid coating (CA-MNP) for studies in hydrogels. All samples were subjected to an AMF (40 kA/m, 270 kHz) for 30 min, and from the recorded time-temperature curve, the specific loss power (SLP) value was calculated. In-vitro experiments were performed with L929 cells, which were incubated for 24 h with 225 μg(Fe)/mL ML dispersed in RPMI cell medium. The results of the SLP values were analyzed regarding the internalized ML amount with respect to ML residuals in RMPI medium and compared to fully immobilized ML after freeze-drying (FD): The SLP value of 10.1 % intracellular ML decreased by 20 %, the SLP value of 100 % intracellular ML decreased by 60 % and that of FD-ML decreased by 70 % (Fig 1a). The influence of gradual immobilization of MNP on the heating was investigated by mixing CA-MNP in low-melting agarose and polyacrylamide hydrogels. In agarose and polyacrylamide gels the mean mesh size can be tuned via the amount of monomers and cross-linkers, respectively, and in this way the state of MNP immobilization is influenced. SLP values decreased by up to 40 % in agarose gels for mesh sizes smaller than the hydrodynamic size dH = 20.6 nm. A comparable decrease was observed in polyacrylamide gels (Fig 1b & c). We attribute this drop in SLP values to a gradual immobilization of MNP trapped in the hydrogels, which blocks particle relaxation and therefore decreases heating efficiency. This agrees very well with the results of the in-vitro measurements. The relative difference in the SLP drop in agarose and polyacrylamide hydrogels for similar mesh sizes might be explained by their gel-specific microstructures, which influence the MNP freedom of movement. For validation of these results, further investigations of the relaxation behavior of such trapped MNP via magnetic particle spectroscopy are currently under progress.
Easy-read and large language models: on the ethical dimensions of LLM-based text simplification
(2024)
The production of easy-read and plain language is a challenging task, requiring well-educated experts to write context-dependent simplifications of texts. Therefore, the domain of easy-read and plain language is currently restricted to the bare minimum of necessary information. Thus, even though there is a tendency to broaden the domain of easy-read and plain language, the inaccessibility of a significant amount of textual information excludes the target audience from partaking or entertainment and restricts their ability to live life autonomously. Large language models can solve a vast variety of natural language tasks, including the simplification of standard language texts to easy-read or plain language. Moreover, with the rise of generative models like GPT, easy-read and plain language may be applicable to all kinds of natural language texts, making formerly inaccessible information accessible to marginalized groups like, a.o., non-native speakers, and people with mental disabilities. In this paper, we argue for the feasibility of text simplification and generation in that context, outline the ethical dimensions, and discuss the implications for researchers in the field of ethics and computer science.
The quest for scientifically advanced and sustainable solutions is driven by growing environmental and economic issues associated with coal mining, processing, and utilization. Consequently, within the coal industry, there is a growing recognition of the potential of microbial applications in fostering innovative technologies. Microbial-based coal solubilization, coal beneficiation, and coal dust suppression are green alternatives to traditional thermochemical and leaching technologies and better meet the need for ecologically sound and economically viable choices. Surfactant-mediated approaches have emerged as powerful tools for modeling, simulation, and optimization of coal-microbial systems and continue to gain prominence in clean coal fuel production, particularly in microbiological co-processing, conversion, and beneficiation. Surfactants (surface-active agents) are amphiphilic compounds that can reduce surface tension and enhance the solubility of hydrophobic molecules. A wide range of surfactant properties can be achieved by either directly influencing microbial growth factors, stimulants, and substrates or indirectly serving as frothers, collectors, and modifiers in the processing and utilization of coal. This review highlights the significant biotechnological potential of surfactants by providing a thorough overview of their involvement in coal biodegradation, bioprocessing, and biobeneficiation, acknowledging their importance as crucial steps in coal consumption.
Dieses Buch lädt dazu ein, die Welt um uns herum aus einem neuen Blickwinkel zu betrachten und dabei die spannende Verbindung zwischen der Mathematik und unserem täglichen Leben zu entdecken – denn um die Technologien und Entwicklungen unserer modernen Gesellschaft zu verstehen, benötigen wir ein intuitives Verständnis grundlegender mathematischer Ideen. In diesem Buch geht es um diese Grundlagen, vor allem aber um ihre praktische Anwendung im Alltag: Gemeinsam begeben wir uns auf eine unterhaltsame Reise und entdecken dabei, wie Mathematik in vielfältiger Weise allgegenwärtig ist. Anschauliche Beispiele zeigen, wie wir täglich – oft unbewusst – mathematische Ideen nutzen und wie wir mit Hilfe von Mathematik bessere Entscheidungen treffen können.
Nach einer Einführung in Algorithmen und Optimierungsprobleme, geht es im weiteren Verlauf um die Modellierung von Zufall und Unsicherheiten. Zum Ende des Buchs werden die Themen zusammengeführt und Algorithmen für Anwendungen besprochen, bei denen der Zufall eine entscheidende Rolle spielt.
Sexism in online media comments is a pervasive challenge that often manifests subtly, complicating moderation efforts as interpretations of what constitutes sexism can vary among individuals. We study monolingual and multilingual open-source text embeddings to reliably detect sexism and misogyny in Germanlanguage online comments from an Austrian newspaper. We observed classifiers trained on text embeddings to mimic closely the individual judgements of human annotators. Our method showed robust performance in the GermEval 2024 GerMS-Detect Subtask 1 challenge, achieving an average macro F1 score of 0.597 (4th place, as reported on Codabench). It also accurately predicted the distribution of human annotations in GerMS-Detect Subtask 2, with an average Jensen-Shannon distance of 0.301 (2nd place). The computational efficiency of our approach suggests potential for scalable applications across various languages and linguistic contexts.
Purpose: Impaired paravascular drainage of β-Amyloid (Aβ) has been proposed as a contributing cause for sporadic Alzheimer’s disease (AD), as decreased cerebral blood vessel pulsatility and subsequently reduced propulsion in this pathway could lead to the accumulation and deposition of Aβ in the brain. Therefore, we hypothesized that there is an increased impairment in pulsatility across AD spectrum.
Patients and Methods: Using transcranial color-coded duplex sonography (TCCS) the resistance and pulsatility index (RI; PI) of the middle cerebral artery (MCA) in healthy controls (HC, n=14) and patients with AD dementia (ADD, n=12) were measured. In a second step, we extended the sample by adding patients with mild cognitive impairment (MCI) stratified by the presence (MCI-AD, n=8) or absence of biomarkers (MCI-nonAD, n=8) indicative for underlying AD pathology, and compared RI and PI across the groups. To control for atherosclerosis as a confounder, we measured the arteriolar-venular-ratio of retinal vessels.
Results: Left and right RI (p=0.020; p=0.027) and left PI (p=0.034) differed between HC and ADD controlled for atherosclerosis with AUCs of 0.776, 0.763, and 0.718, respectively. The RI and PI of MCI-AD tended towards ADD, of MCI-nonAD towards HC, respectively. RIs and PIs were associated with disease severity (p=0.010, p=0.023).
Conclusion: Our results strengthen the hypothesis that impaired pulsatility could cause impaired amyloid clearance from the brain and thereby might contribute to the development of AD. However, further studies considering other factors possibly influencing amyloid clearance as well as larger sample sizes are needed.
Purpose: A precise determination of the corneal diameter is essential for the diagnosis of various ocular diseases, cataract and refractive surgery as well as for the selection and fitting of contact lenses. The aim of this study was to investigate the agreement between two automatic and one manual method for corneal diameter determination and to evaluate possible diurnal variations in corneal diameter.
Patients and Methods: Horizontal white-to-white corneal diameter of 20 volunteers was measured at three different fixed times of a day with three methods: Scheimpflug method (Pentacam HR, Oculus), placido based topography (Keratograph 5M, Oculus) and manual method using an image analysis software at a slitlamp (BQ900, Haag-Streit).
Results: The two-factorial analysis of variance could not show a significant effect of the different instruments (p = 0.117), the different time points (p = 0.506) and the interaction between instrument and time point (p = 0.182). Very good repeatability (intraclass correlation coefficient ICC, quartile coefficient of dispersion QCD) was found for all three devices. However, manual slitlamp measurements showed a higher QCD than the automatic measurements with the Keratograph 5M and the Pentacam HR at all measurement times.
Conclusion: The manual and automated methods used in the study to determine corneal diameter showed good agreement and repeatability. No significant diurnal variations of corneal diameter were observed during the period of time studied.
Metathese von Ölsäure und Derivaten ist ein interessanter Weg für die Synthese bifunktioneller Verbindungen aus nachwachsenden Rohstoffen. Verwendet wurden Ru-Katalysatoren der zweiten Generation, welche eine hohe Toleranz gegenüber funktionellen Gruppen und Verunreinigungen aufweisen. Trotz des Einsatzes technischer Edukte waren Umsetzungen mit niedrigen Katalysatormengen (0.001 – 0.01 mol-%) möglich, mit Ausbeuten entsprechend der Literatur. Kreuzmetathesen ermöglichten variable Kettenlängen und Funktionalitäten der Monomere, die Produktgewinnung ist jedoch aufwändig. Selbstmetathese lieferte C18-bifunktionelle Verbindungen, welche einfach durch Destillation oder Kristallisation isoliert werden können. Neben der katalystischen Umsetzung wurde auch die Produktgewinnung untersucht und für ausgewählte Produkte auch im größeren Maßstab durchgeführt.
Self metathesis of oleochemicals offers a variety of bifunctional compounds, that can be used as monomer for polymer production. Many precursors are in huge scales available, like oleic acid ester (biodiesel), oleyl alcohol (tensides), oleyl amines (tensides, lubricants). We show several ways to produce and separate and purify C18-α,ω-bifunctional compounds, using Grubbs 2nd Generation catalysts, starting from technical grade educts.
