Refine
Year of publication
- 2024 (352)
- 2023 (481)
- 2022 (477)
- 2021 (527)
- 2020 (487)
- 2019 (415)
- 2018 (415)
- 2017 (242)
- 2016 (200)
- 2015 (344)
- 2014 (365)
- 2013 (349)
- 2012 (373)
- 2011 (423)
- 2010 (417)
- 2009 (391)
- 2008 (379)
- 2007 (372)
- 2006 (400)
- 2005 (385)
- 2004 (378)
- 2003 (292)
- 2002 (264)
- 2001 (155)
- 2000 (75)
- 1999 (17)
- 1998 (1)
- 1997 (1)
- 1995 (2)
- 1994 (1)
- 1991 (1)
- 1988 (2)
- 1986 (1)
- 1971 (1)
Document Type
- Doctoral Thesis (8985) (remove)
Language
- German (6158)
- English (2822)
- French (4)
- Multiple languages (1)
Keywords
- Maus (121)
- Signaltransduktion (104)
- Genexpression (99)
- Taufliege (92)
- Deutschland (83)
- T-Lymphozyt (75)
- Tissue Engineering (73)
- Apoptosis (70)
- Herzinsuffizienz (67)
- Thrombozyt (61)
Institute
- Graduate School of Life Sciences (1032)
- Theodor-Boveri-Institut für Biowissenschaften (799)
- Physikalisches Institut (413)
- Medizinische Klinik und Poliklinik I (316)
- Institut für Pharmazie und Lebensmittelchemie (294)
- Institut für Anorganische Chemie (261)
- Klinik und Poliklinik für Allgemein-, Viszeral-, Gefäß- und Kinderchirurgie (Chirurgische Klinik I) (258)
- Klinik und Poliklinik für Psychiatrie, Psychosomatik und Psychotherapie (234)
- Institut für Organische Chemie (227)
- Medizinische Klinik und Poliklinik II (219)
Schriftenreihe
Sonstige beteiligte Institutionen
- Fraunhofer-Institut für Silicatforschung ISC (8)
- Helmholtz Institute for RNA-based Infection Research (HIRI) (8)
- Universitätsklinikum Würzburg (5)
- Fraunhofer Institut für Silicatforschung ISC (3)
- Fraunhofer-Institut für Silicatforschung (3)
- Klinikum Fulda (3)
- König-Ludwig-Haus Würzburg (3)
- Technische Hochschule Nürnberg Georg Simon Ohm (3)
- Universitätsklinikum Münster (3)
- CHC Würzburg (Comprehensive Hearing Center) (2)
ResearcherID
- B-1911-2015 (1)
- B-4606-2017 (1)
- C-2593-2016 (1)
- D-1250-2010 (1)
- D-3057-2014 (1)
- I-5818-2014 (1)
- J-8841-2015 (1)
- M-1240-2017 (1)
- N-2030-2015 (1)
- N-3741-2015 (1)
EU-Project number / Contract (GA) number
- 311781 (1)
- 320377 (1)
- EU (FP7/ 2007-2013) (1)
Ziel dieser klinisch-experimentellen Studie war die Untersuchung
elektromyographischer Kaumuskelprofile von beschwerdefreien Probandinnen
unterschiedlichen Bruxismusgrades nach sensomotorischem Training. Die aufgestellte
Hypothese postulierte signifikante Unterschiede der EMG-Parameter nach
sensomotorischem Training. Nach einer Ruhephase ohne Intervention sollten die
Unterschiede in den Ausgangszustand zurückkehren. Hierzu wurden 40 Probandinnen
mit einem Durchschnittsalter von 24,58 ± 2,72 Jahren über einen Zeitraum von fünf
Wochen untersucht. Die Probandinnen wurden mittels zufälliger Verteilung und
altersentsprechend gematcht in zwei gleichgroße Gruppen eingeteilt. Sowohl die
Teilnehmerinnen der Kontrollgruppe, als auch die der Interventionsgruppe absolvierten
im Verlauf der Studie drei elektromyographische Messungen. Nach einer einwöchigen
Voruntersuchungsphase fand die erste Messung (T1) statt. Nach drei Wochen und nach
fünf Wochen erfolgten die zweite (T2) und die dritte Messung (T3). Während der
Messungen führten die Probandinnen kraftkontrollierte Übungen mit drei
submaximalen Kraftleveln und maximalen Kräften aus. Zusätzlich absolvierte die
Interventionsgruppe zwischen T1 und T2 ein sensomotorisches Training mit dem
RehaBite®-Gerät. Die bipolaren Oberflächen-EMG-Ableitungen erfolgten für beide Mm.
masseteres und Mm. temporales. Insgesamt wurden acht Muskelareale aufgezeichnet.
Sechs für die Mm. masseteres und zwei für die Mm. temporales. Die submaximalen
Kräfte wurden als RMS %MVC und die maximalen Kräfte als RMS MVC verglichen. Die
statistischen Vergleiche erfolgten anhand von T-Tests und Mixed ANOVAs. Nach
Beurteilung der Ergebnisse konnte kein signifikanter Effekt des sensomotorischen
Trainings identifiziert werden. Die aufgestellte Hypothese muss daher abgelehnt
werden. Für das erste der drei submaximalen Kraftlevel konnte für die Initialmessung
(T1) ein signifikanter Unterschied zwischen Probandinnen mit und ohne Schlafbruxismus
in zwei der acht Muskelareale festgestellt werden. Für zukünftige Folgeuntersuchungen
zur Wirksamkeit des sensomotorischen Trainings bei Bruxismus ist die Verlängerung des
Interventionsintervalls sowie eine Vergrößerung des Studienkollektivs samt Einschluss
männlicher Probanden empfehlenswert.
Zweck: Obwohl Bruxismus im Wesentlichen als Verhalten mit multifaktorieller Genese gilt, konnten bisher nicht eindeutig die damit assoziierten Komorbiditäten aufgeklärt werden. Die Zielsetzung war, anamnestische und psychosoziale Unterschiede zwischen Proband(inn)en mit und ohne möglichem bzw. definitivem Bruxismus zu ermitteln. Darüber hinaus sollte die Übereinstimmung verschiedener Instrumente zur Bruxismus-Diagnostik und der Effekt von zwei Interventionen (bedingte elektrische Stimulation (CES) und Kautraining) analysiert werden.
Methoden: In dieser klinischen, explorativen Studie wurden 76 Proband(inn)en untersucht. Die Proband(inn)en wurden in die drei Gruppen Kontrollgruppe, aktive Interventionsgruppe und Rehabite Interventionsgruppe eingeteilt. Die Kontrollgruppe trug ein portables EMG-Gerät (GrindCare) jede Nacht über einen Beobachtungszeitraum von 5 Wochen inaktiv. Die aktive Interventionsgruppe trug es die erste Woche inaktiv, dann 2 Wochen aktiv mit CES und anschließend erneut 2 Wochen inaktiv. Die RehaBite Interventionsgruppe verwendete das GrindCare eine Woche inaktiv, darauf folgte ein zweiwöchiges Kautraining mit einer Bissgabel namens RehaBite aber ohne EMG-Begleitung und die letzten zwei Wochen verliefen ohne Rehabite und GrindCare. Zu Beginn und am Ende des Beobachtungszeitraums füllten alle drei Gruppen die gleichen Fragebögen, u.a. die Oral Behavior Checklist (OBC) und verschiedene Fragebögen zu körperlichen und psychologischen Parametern, aus. Das GrindCare misst die Episoden und ermöglicht damit die Diagnose eines definitiven Schafbruxismus (SB).
Ergebnisse: Es existierten signifikante Unterschiede zwischen Proband(inn)en mit und ohne Bruxismus (möglicher und definitiver SB, möglicher Wachbruxismus (WB), möglicher kombinierter SB und WB) in diversen anamnestischen und psychosozialen Parametern. Außerdem bestand ein signifikanter Zusammenhang zwischen erhöhter Kieferaktivität (diagnostiziert mittels OBC) und SB- sowie WB-Selbstangabe sowie zwischen den Selbstangaben von SB und WB untereinander, nicht jedoch zwischen Fragebögen und apparativer Diagnostik. Die CES bewirkte keine Reduktion der Episoden, dafür verbesserten sich jedoch einzelne körperliche und psychosoziale Parameter in der aktiven bzw. in der Rehabite Gruppe im Laufe des Beobachtungszeitraums.
Fazit: Personen mit und ohne möglichem bzw. definitivem Bruxismus unterschieden sich in verschiedenen anamnestischen, körperlichen und psychosozialen Eigenschaften voneinander. Außerdem bestehen signifikante Korrelationen zwischen SB und WB laut Selbstangabe, nicht jedoch bezüglich der apparativen Bruxismus-Diagnostik mit dem GrindCare. Während die Episoden nicht durch die CES gesenkt wurden, verringerten sich -eventuell durch RehaBite bzw. CES bedingt- bestimmte Beschwerden. Weiterer Forschungsbedarf besteht, um auf der Basis größerer Stichproben die gefundenen Auffälligkeiten statistisch abzusichern.
Spielfilme gelten im Sinne einer „Visual History“ als wertvolle medizinhistorische Quellen. Dass die Arztfilme der DDR-Zeit ebenfalls als solche zu betrachten sind, da sie realhistorische Parallelen aufweisen, soll dieses Projekt zeigen. Anhand dreier Spielfilme aus den verschiedenen Jahrzehnten, in denen die DDR Bestand hatte, werden für die damalige Zeit typische Konflikte und Themen des Arztseins in der DDR näher beleuchtet. Die drei Hauptfilme dieses Projekts – „Ärzte“ (1960), „Dr. med. Sommer II“ (1970) und „Ärztinnen“ (1983/84) – wurden hinsichtlich ihrer Hauptfiguren, Filmtechnik und -musik analysiert und mittels Filmkritiken, Werbematerial und Aufsätzen aus der damaligen Zeit in einen realhistorischen Kontext gesetzt. Außerdem wurden zur besseren filmgeschichtlichen Einordnung weitere Arztfilme aus der DDR in die Arbeit miteinbezogen. Das Medium Film spielte in Zeiten der DDR auch zur allgemeinen gesellschaftlichen Beeinflussung eine wichtige Rolle. Durch die Analyse der Filme unter Einbeziehung von historischen Zeitungsartikeln und Werbematerial wird das Bild eines sozialistischen Idealmenschen und -arztes, wie von der SED propagiert, dargestellt und untersucht.
Die vorliegende Arbeit widmet sich der wissenschaftlichen Untersuchung der Drittbeteiligung im Verfahren vor dem EGMR. Die Arbeit unterscheidet dabei zwischen vier potentiellen Drittbeteiligungsakteuren und setzt sich spezifisch mit den verschiedenen, bislang wenig behandelten Fragestellungen der Drittbeteiligung anderer Personen als derjenigen des Beschwerdeführers und dem gegnerischen Konventionsstaat auf der Grundlage des Art. 36 Abs. 2 EMRK auseinander. Als Herzstück der Arbeit wird der Einfluss der Stellungnahmen Drittbeteiligter auf die Judikatur des EGMR untersucht. Im Wege eines Vergleichs mit der verfahrensrechtlichen Ausgestaltung der Drittbeteiligung vor anderen internationalen Spruchkörpern erfolgt abschließend eine wertende Betrachtung des derzeitigen Rechtsrahmens der Drittbeteiligung vor dem EGMR.
Mit der EEG-Umlage wurden bis zum Jahr 2023 die Förderkosten für den Ökostromausbau auf die Stromverbraucher umgelegt. Ursprünglich knüpfte die Umlagepflicht an eine Stromlieferung an, weshalb der eigenerzeugte Strom nicht erfasst war. Das sog. Eigenstromprivileg wurde mit dem EEG 2014 grundsätzlich abgeschafft. Allerdings führten diverse Ausnahmetatbestände dazu, dass ein Großteil der Eigenverbrauchsmengen weiterhin privilegiert waren.
Die Arbeit untersucht, in welchem Maße dieser Flickenteppich an unterschiedlichen Regelungen auf die verfassungs- und europarechtlichen Rahmenbedingungen zurückzuführen ist. Neben einer systematischen Erfassung des einfachgesetzlichen Rechtsrahmens erfolgt eine Analyse, inwiefern das Verfassungs- und Europarecht den gesetzlichen Gestaltungsspielraum für staatlich veranlasste, jedoch privatrechtlich ausgestaltete Umlagesysteme einschränkt.
Acceleration is a central aim of clinical and technical research in magnetic resonance imaging (MRI) today, with the potential to increase robustness, accessibility and patient comfort, reduce cost, and enable entirely new kinds of examinations. A key component in this endeavor is image reconstruction, as most modern approaches build on advanced signal and image processing. Here, deep learning (DL)-based methods have recently shown considerable potential, with numerous publications demonstrating benefits for MRI reconstruction. However, these methods often come at the cost of an increased risk for subtle yet critical errors. Therefore, the aim of this thesis is to advance DL-based MRI reconstruction, while ensuring high quality and fidelity with measured data. A network architecture specifically suited for this purpose is the variational network (VN). To investigate the benefits these can bring to non-Cartesian cardiac imaging, the first part presents an application of VNs, which were specifically adapted to the reconstruction of accelerated spiral acquisitions. The proposed method is compared to a segmented exam, a U-Net and a compressed sensing (CS) model using qualitative and quantitative measures. While the U-Net performed poorly, the VN as well as the CS reconstruction showed good output quality. In functional cardiac imaging, the proposed real-time method with VN reconstruction substantially accelerates examinations over the gold-standard, from over 10 to just 1 minute. Clinical parameters agreed on average.
Generally in MRI reconstruction, the assessment of image quality is complex, in particular for modern non-linear methods. Therefore, advanced techniques for precise evaluation of quality were subsequently demonstrated.
With two distinct methods, resolution and amplification or suppression of noise are quantified locally in each pixel of a reconstruction. Using these, local maps of resolution and noise in parallel imaging (GRAPPA), CS, U-Net and VN reconstructions were determined for MR images of the brain. In the tested images, GRAPPA delivers uniform and ideal resolution, but amplifies noise noticeably. The other methods adapt their behavior to image structure, where different levels of local blurring were observed at edges compared to homogeneous areas, and noise was suppressed except at edges. Overall, VNs were found to combine a number of advantageous properties, including a good trade-off between resolution and noise, fast reconstruction times, and high overall image quality and fidelity of the produced output. Therefore, this network architecture seems highly promising for MRI reconstruction.
Articular cartilage defects represent one of the most challenging clinical problem for orthopedic surgeons and cartilage damage after trauma can result in debilitating joint pain, functional impairment and in the long-term development of osteoarthritis. The lateral cartilage-cartilage integration is crucial for the long-term success and to prevent further tissue degeneration. Tissue adhesives and sealants are becoming increasingly more popular and can be a beneficial approach in fostering tissue integration, particularly in tissues like cartilage where alternative techniques, such as suturing, would instead introduce further damage. However, adhesive materials still require optimization regarding the maximization of adhesion strength on the one hand and long-term tissue integration on the other hand. In vitro models can be a valuable support in the investigation of potential candidates and their functional mechanisms. For the conducted experiments within this work, an in vitro disc/ring model obtained from porcine articular cartilage tissue was established. In addition to qualitative evaluation of regeneration, this model facilitates the implementation of biomechanical tests to quantify cartilage integration strength. Construct harvesting for histology and other evaluation methods could be standardized and is ethically less questionable compared to in vivo testing. The opportunity of cell culture technique application for the in vitro model allowed a better understanding of cartilage integration processes.
Tissue bonding requires chemical or physical interaction of the adhesive material and the substrate. Adhesive hydrogels can bind to the defect interface and simultaneously fill the gap of irregularly shaped defect voids. Fibrin gels are derived from the physiological blood-clot formation and are clinically applied for wound closure. Within this work, comparisons of different fibrin glue formulations with the commercial BioGlue® were assessed, which highlighted the need for good biocompatibility when applied on cartilage tissue in order to achieve satisfying long-term integration. Fibrin gel formulations can be adapted with regard to their long-term stability and when applied on cartilage disc/ring constructs improved integrative repair is observable. The kinetic of repairing processes was investigated in fibrin-treated cartilage composites as part of this work. After three days in vitro cultivation, deposited extracellular matrix (ECM) was obvious at the glued interface that increased further over time. Interfacial cell invasion from the surrounding native cartilage was detected from day ten of tissue culture. The ECM formation relies on molecular factors, e.g., as was shown representatively for ascorbic acid, and contributes to increasing integration strengths over time. The experiments performed with fibrin revealed that the treatment with a biocompatible adhesive that allows cartilage neosynthesis favors lateral cartilage integration in the long term. However, fibrin has limited immediate bonding strength, which is disadvantageous for use on articular cartilage that is subject to high mechanical stress. The continuing aim of this thesis was to further develop adhesive mechanisms and new adhesive hydrogels that retain the positive properties of fibrin but have an increased immediate bonding strength.
Two different photochemical approaches with the advantage of on-demand bonding were tested. Such treatment potentially eases the application for the professional user. First, an UV light induced crosslinking mechanism was transferred to fibrin glue to provide additional bonding strength. For this, the cartilage surface was functionalized with highly reactive light-sensitive diazirine groups, which allowed additional covalent bonds to the fibrin matrix and thus increased the adhesive strength. However, the disadvantages of this approach were the multi-step bonding reactions, the need for enzymatic pretreatment of the cartilage, expensive reagents, potential UV-light damage, and potential toxicity hazards. Due to the mentioned disadvantages, no further experiments, including long-term culture, were carried out. A second photosensitive approach focused on blue light induced crosslinking of fibrinogen (RuFib) via a photoinitiator molecule instead of using thrombin as a crosslinking mediator like in normal fibrin glue. The used ruthenium complex allowed inter- and intramolecular dityrosine binding of fibrinogen molecules. The advantage of this method is a one-step curing of fibrinogen via visible light that further achieved higher adhesive strengths than fibrin. In contrast to diazirine functionalization of cartilage, the ruthenium complex is of less toxicological concern. However, after in vitro cultivation of the disc/ring constructs, there was a decrease in integration strength. Compared to fibrin, a reduced cartilage synthesis was observed at the defect. It is also disadvantageous that a direct adjustment of the adhesive can only be made via protein concentration, since fibrinogen is a natural protein that has a fixed number of tyrosine binding sites without chemical modification.
An additional cartilage adhesive was developed that is based on a mussel-inspired adhesive mechanism in which reactivity to a variety of substrates is enabled via free DOPA amino acids. DOPA-based adhesion is known to function in moist environments, a major advantage for application on water-rich cartilage tissue surrounded by synovial liquid. Reactive DOPA groups were synthetically attached to a polymer, here POx, to allow easy chemical modifiability, e.g. insertion of hydrolyzable ester motifs for tunable degradation. The possibility of preparing an adhesive hybrid hydrogel of POx in combination with fibrinogen led to good cell compatibility as was similarly observed with fibrin, but with increased immediate adhesive strength. Degradation could be adjusted by the amount of ester linkages on the POx and a direct influence of degradation rates on the development of integration in the in vitro model could be shown.
Hydrogels are well suited to fill defect gaps and immediate integration can be achieved via adhesive properties. The results obtained show that for the success of long-term integration, a good ability of the adhesive to take up synthesized ECM components and cells to enable regeneration is required. The degradation kinetics of the adhesive must match the remodeling process to avoid intermediate loss of integration power and to allow long-term firm adhesion to the native tissue.
Hydrogels are not only important as adhesives for smaller lesions, but also for filling large defect volumes and populating them with cells to produce tissue engineered cartilage. Many different hydrogel types suitable for cartilage synthesis are reported in the literature. A long-term stable fibrin formulation was tested in this work not only as an adhesive but also as a bulk hydrogel construct. Agarose is also a material widely used in cartilage tissue engineering that has shown good cartilage neosynthesis and was included in integration assessment. In addition, a synthetic hyaluronic acid-based hydrogel (HA SH/P(AGE/G)) was used. The disc/ring construct was adapted for such experiments and the inner lumen of the cartilage ring was filled with the respective hydrogel. In contrast to agarose, fibrin and HA-SH/P(AGE/G) gels have a crosslink mechanism that led to immediate bonding upon contact with cartilage during curing. The enhanced cartilage neosynthesis in agarose compared to the other hydrogel types resulted in improved integration during in vitro culture. This shows that for the long-term success of a treatment, remodeling of the hydrogel into functional cartilage tissue is a very high priority. In order to successfully treat larger cartilage defects with hydrogels, new materials with these properties in combination with chemical modifiability and a direct adhesion mechanism are one of the most promising approaches.
In the initiation phase of acute graft-versus-host disease (aGvHD), CD4+ T cells are activated by hematopoietic antigen presenting cells in secondary lymphoid organs whereas in effector phase by non-hematopoietic cells in the small intestine. We hypothesized that alloreactive CD4+ T cells primarily home to the secondary lymphoid organs subsequent to allogeneic hematopoietic cell transplantation in the initiation phase of aGvHD and are activated by the non-hematopoietic lymph node stromal cells via MHC class II. To test this hypothesis, we employed CD4+ T cell-dependent major mismatch aGvHD mouse model to study this correlation.
Upon analyzing the early events following allo-HCT with bioluminescence imaging, flow cytometry and whole-mount light sheet fluorescence microscopy, we found that allogeneic T cells exclusively home to the spleen, lymph nodes and the Peyer’s patches and not to the intestinal lamina propria in the initiation phase of aGvHD. Utilizing mice devoid of partial or complete hematopoietic antigen presentation we could show allogeneic CD4+ T cells activation in the lymphoid organs of MHCIIΔCD11c and MHCIIΔ BM chimeric mice early after allo-HCT. MHCIIΔ BM chimeras failure of thymic negative selection and developing tissue wasting disease upon syn-HCT deemed them unsuitable to study non-hematopoietic antigen presentation in aGvHD. To overcome this challenge, we generated MHCIIΔVav1 mice that lack MHC class II expression on all hematopoietic cells. MHCIIΔVav1 mice were susceptible to aGvHD and LNSCs from these animals activated allogeneic CD4+ T cells in mixed lymphocyte reaction. Likewise, mesenteric lymph nodes from CD11c.DTR mice surgically transplanted into a MHCIIΔ mouse could activate CD4+ T cells in vivo, clearly demonstrating LNSCs as non-hematopoietic APCs of the lymphoid organs.
We specifically target lymph node stromal cell subsets via the Cre/loxP system, we employed single cell RNA sequencing and selected Ccl19 and VE-Cadherin to specifically target the fibroblastic reticular cells and endothelial cells of the lymph nodes respectively. In MHCIIΔCcl19 mice, alloreactive CD4+ T cells activation was discreetly reduced in the initiation phase of aGvHD whereas absence of MHCII on fibroblastic reticular cells resulted in hyper-activation of allogeneic CD4+ T cells leading to poor survival. This phenotype was modulated by the regulatory T cells that were able to rescue H2-Ab1fl mice but not the MHCIIΔCcl19 subsequent to GvHD.
Knock-out of MHCII on endothelial cells MHCIIΔVE Cadherin, resulted only in modest reduction of CD4+ T cells activation in the initiation phase of GvHD, conversely MHCIIΔVE Cadherin mice showed a protective phenotype compared against littermates H2-Ab1fl mice in long-term survival. Furthermore, to pin-point endothelial cells MHCII antigen presentation we generated MHCIIΔVE Cadherin ΔVav1 animals devoid of antigen presentation in both endothelial and hematopoietic compartments. LNSCs from MHCIIΔVE Cadherin ΔVav1 were unable to activate alloreactive CD4+ T cells in mixed lymphocyte reaction.
Altogether, we demonstrate for the first time that MHC class II on the lymph node stromal cells plays a crucial role in the modulation of allogeneic CD4+ T cells in the initiation and later in the effector phase of graft-versus-host-disease.
In the face of threat, animals react with a defensive reaction to avoid or reduce harm. This defensive reaction encompasses apart from behavioral changes also physiological, analgetic, and endocrine adaptations. Nonetheless, most animal studies on fear and anxiety are based on behavioral observations only, disregarding other aspects of the defensive reaction, or integrating their inter-related dynamics only insufficiently. The first part of this thesis aimed in characterizing patterned associations of behavioral and physiological responses, termed integrated defensive states. Analyzing cardiac and behavioral responses in mice undergoing multiple fear and anxiety paradigms revealed a complex and dynamic interaction of those readouts on both, short and long timescales. Microstates, stereotypical combinations of i.e. freezing and decelerating heart rates, are short-lasting and were, in turn, shown to be influenced by slow acting macrostate changes. One of those higher order macrostates, called `rigidity`, was defined as a latent process that constrains the range of momentary displayed heart rate values. Furthermore, integrated defensive states were found to be highly dependent on the cue and the context the animals are confronted with. Importantly, same behavioral observations, i.e. freezing, were associated with distinct cardiac responses, highlighting the importance of multivariate analysis of integrated defensive states. Defensive states are orchestrated by the brain, which has evolved evolutionary conserved survival circuits. A central brain area of these circuits is the periaqueductal gray (PAG) in the midbrain. It plays a pivotal role in mediating defensive states, as it receives signals about external and internal information from multiple brain regions and sends information to both, higher order brain areas as well as to the brainstem ultimately causing the execution of threat responses. In the second part of this thesis, different neuronal circuit elements in the PAG were optically manipulated in order to gain mechanistic insight into the defense network in the brain underlying the previously delineated cardio-behavioral defensive states. Optical activation of glutamatergic PAG neurons evoked heterogeneous, light-intensity dependent responses. However, a further molecular restriction of the glutamatergic neuronal population targeting only Chx10+ neurons, led to a cardio-behavioral state that resembled spontaneous freezing-bradycardia bouts.
In summary, this thesis presents a multivariate description of defensive states, which includes the complex interaction of cardiac and behavioral responses on different timescales and, furthermore, functionally dissects different excitatory and inhibitory PAG circuit elements mediating these defensive states.
This Ph.D. thesis has addressed several main issues in current ASSB research within four studies. Ceramic ASSBs are meant to enable the implementation of Li-metal anodes and high voltage cathode materials, which would increase energy density, power density, life time as well as safety aspects in comparison with commercially available liquid electrolyte LiBs. In this thesis, several scientific questions arising on the cathode side of ASSBs have been focused on. With respect to the target system of a ternary composite bulk cathode consisting of ceramic active material, ceramic SSE and an electrically conductive component, studies about the thermal stabilities of these components and their impact on the electrochemical performance have been conducted. Particulate bulk cathode composites have to fulfil electrochemical, chemical, mechanical and structural requirements in order to compete with commercial LiBs. Particularly, the production process requires high-temperature sintering to obtain firmly bonded contacts in order to maximize the electrochemically active area, charge transfer and ionic conduction. However, interdiffusion, intermixing and decomposition of the initial components during sintering result in low-performing ASSBs so far.
These side reactions during high-temperature treatment have been investigated in order to gain a better understanding of these mechanisms and to enable a better controlling of the manufacturing process as well as to simplify the choice of material combinations. The first two parts of this thesis deal with the thermal stability of the ceramic SSE LATP in combination with various active materials and with the validation of a probable improvement of the sintering process due to liquid phase sintering of LATP by adding Li3PO4. In the third and fourth parts, the impact of interdiffusion, intermixing and decomposition on the electrochemical performance of TF-SSBs based on the active material LMO and the ceramic SSE Ga-LLZO has been investigated.