Postoperative Veränderungen der distalen Aortenwandarchitektur bei Patienten nach chirurgischer Behandlung einer akuten Aortendissektion Typ A

Die Arbeit handelt von postoperativen Veränderungen der distalen Aortenwandarchitektur bei Patienten nach chirurgischer Behandlung einer akuten Aortendissektion Typ A.:Abkürzungsverzeichnis I Inhaltsverzeichnis II 1. Einleitung 1 1.1 Historischer Exkurs zur Leipziger Herzchirurgie 1 1.2 Anatomie der Aorta 2 1.3 Erkrankungen der thorakalen Aorta 4 1.4 Die akute Aortendissektion 4 1.5 Klassifikation 4 1.6 Ätiologie und Pathophysiologie 7 1.7 Klinik 9 2. Diagnostik 10 3. Operative Versorgung 13 3.1 Operationsindikation 13 3.2 Operationsverfahren 14 3.2.1 Aorta ascendens 14 3.2.2 Operationserweiterung in den Aortenbogen 17 3.2.3 Operationserweiterung in die Aorta descendens 17 Zielstellung 19 4. Originalpublikation 20 5. Zusammenfassung der Arbeit 30 Literaturverzeichnis III Tabellenverzeichnis VII Abbildungsverzeichnis VIII Darstellung des wissenschaftlichen Beitrags IX Erklärung über die eigenständige Abfassung der Arbeit X Lebenslauf XI Danksagung XII

Augmented Cross-Selling Through Explainable AI—A Case From Energy Retailing

The advance of Machine Learning (ML) has led to a strong interest in this technology to support decision making. While complex ML models provide predictions that are often more accurate than those of traditional tools, such models often hide the reasoning behind the prediction from their users, which can lead to lower adoption and lack of insight. Motivated by this tension, research has put forth Explainable Artificial Intelligence (XAI) techniques that uncover patterns discovered by ML. Despite the high hopes in both ML and XAI, there is little empirical evidence of the benefits to traditional businesses. To this end, we analyze data on 220,185 customers of an energy retailer, predict cross-purchases with up to 86% correctness (AUC), and show that the XAI method SHAP provides explanations that hold for actual buyers. We further outline implications for research in information systems, XAI, and relationship marketing

Overcoming Anchoring Bias: The Potential of AI and XAI-based Decision Support

Information systems (IS) are frequently designed to leverage the negative effect of anchoring bias to influence individuals’ decision-making (e.g., by manipulating purchase decisions). Recent advances in Artificial Intelligence (AI) and the explanations of its decisions through explainable AI (XAI) have opened new opportunities for mitigating biased decisions. So far, the potential of these technological advances to overcome anchoring bias remains widely unclear. To this end, we conducted two online experiments with a total of N=390 participants in the context of purchase decisions to examine the impact of AI and XAI-based decision support on anchoring bias. Our results show that AI alone and its combination with XAI help to mitigate the negative effect of anchoring bias. Ultimately, our findings have implications for the design of AI and XAI-based decision support and IS to overcome cognitive biases

Addressing Learners\u27 Heterogeneity in Higher Education: An Explainable AI-based Feedback Artifact for Digital Learning Environments

Due to the advent of digital learning environments and the freedom they offer for learners, new challenges arise for students\u27 self-regulated learning. To overcome these challenges, the provision of feedback has led to excellent results, such as less procrastination and improved academic performance. Yet, current feedback artifacts neglect learners’ heterogeneity when it comes to prescriptive feedback that should meet personal characteristics and self-regulated learning skills. In this paper, we derive requirements from self-regulated learning theory for a feedback artifact that takes learners’ heterogeneity into account. Based on these requirements, we design, instantiate, and evaluate an Explainable AI-based approach. The results demonstrate that our artifact is able to detect promising patterns in data on learners\u27 behaviors and characteristics. Moreover, our evaluation suggests that learners perceive our feedback as valuable. Ultimately, our study informs Information Systems research in the design of future Explainable AI-based feedback artifacts that seek to address learners\u27 heterogeneity

Polymer state approximations of Schroedinger wave functions

It is shown how states of a quantum mechanical particle in the Schroedinger representation can be approximated by states in the so-called polymer representation. The result may shed some light on the semiclassical limit of loop quantum gravity.Comment: 11 pages, 1 figure, Conclusions section adde

T Cells of Different Developmental Stages Differ in Sensitivity to Apoptosis Induced by Extracellular NAD

Extracellular nucleotides such as ATP and NAD can profoundly affect the functions of lymphocytes, macrophages, and other cells. We have recently shown that extracellular NAD induces rapid apoptosis in naive T cells by a mechanism involving the ADP-ribosylation of cell surface molecules. In the present paper, we describe that T cells of different developmental stages differ in their sensitivity to NAD-induced apoptosis. Thymocytes were less susceptible than peripheral lymph node T cells, and freshly activated cells were more resistant than resting cells. Sensitivity to NAD-induced apoptosis generally correlated with expression of the ADP-ribosyltransferase ART2.2, which is not expressed on thymocytes and shed from peripheral T cells upon activation. Our findings suggest that NAD-induced apoptosis does not play a role during thymic selection of T cells, but rather may play a role by preventing the activation of unwanted bystander T cells during an immune response, and thus may participate in the control of autoimmunity

Tunable Polyglycerol-Based Redox-Responsive Nanogels for Efficient Cytochrome C Delivery

The sensitivity of therapeutic proteins is a challenge for their use in biomedical applications, as they are prone to degradation and opsonization, thus limiting their potential. This demands for the development of drug delivery systems shielding proteins and releasing them at the site of action. Here, we describe the synthesis of novel polyglycerol-based redox-responsive nanogels and report on their potential as nanocarrier systems for the delivery of cytochrome C (CC). This system is based on an encapsulation protocol of the therapeutic protein into the polymer network. NGs were formed via inverse nanoprecipitation using inverse electron-demand Diels–Alder cyclizations (iEDDA) between methyl tetrazines and norbornenes. Coprecipitation of CC led to high encapsulation efficiencies. Applying physiological reductive conditions of l-glutathione (GSH) led to degradation of the nanogel network, releasing 80% of the loaded CC within 48 h while maintaining protein functionality. Cytotoxicity measurements revealed high potency of CC-loaded NGs for various cancer cell lines with low IC50 values (up to 30 μg·mL−1), whereas free polymer was well tolerated up to a concentration of 1.50 mg·mL−1. Confocal laser scanning microscopy (CLSM) was used to monitor internalization of free and CC-loaded NGs and demonstrate the protein cargo’s release into the cytosol

Gram Scale Synthesis of Dual-Responsive Dendritic Polyglycerol Sulfate as Drug Delivery System

Biocompatible polymers with the ability to load and release a cargo at the site of action in a smart response to stimuli have attracted great attention in the field of drug delivery and cancer therapy. In this work, we synthesize a dual-responsive dendritic polyglycerol sulfate (DR-dPGS) drug delivery system by copolymerization of glycidol, ε-caprolactone and an epoxide monomer bearing a disulfide bond (SSG), followed by sulfation of terminal hydroxyl groups of the copolymer. The effect of different catalysts, including Lewis acids and organic bases, on the molecular weight, monomer content and polymer structure was investigated. The degradation of the polymer backbone was proven in presence of reducing agents and candida antarctica Lipase B (CALB) enzyme, which results in the cleavage of the disulfides and ester bonds, respectively. The hydrophobic anticancer drug Doxorubicin (DOX) was loaded in the polymer and the kinetic assessment showed an enhanced drug release with glutathione (GSH) or CALB as compared to controls and a synergistic effect of a combination of both stimuli. Cell uptake was studied by using confocal laser scanning microscopy with HeLa cells and showed the uptake of the Dox-loaded carriers and the release of the drug into the nucleus. Cytotoxicity tests with three different cancer cell lines showed good tolerability of the polymers of as high concentrations as 1 mg mL−1, while cancer cell growth was efficiently inhibited by DR-dPGS@Dox

Chemical Approaches to Synthetic Drug Delivery Systems for Systemic Applications

Poor water solubility and low bioavailability of active pharmaceutical ingredients (APIs) are major causes of friction in the pharmaceutical industry and represent a formidable hurdle for pharmaceutical drug development. Drug delivery remains the major challenge for the application of new small-molecule drugs as well as biopharmaceuticals. The three challenges for synthetic delivery systems are: (i) controlling drug distribution and clearance in the blood; (ii) solubilizing poorly water-soluble agents, and (iii) selectively targeting specific tissues. Although several polymer-based systems have addressed the first two demands and have been translated into clinical practice, no targeted synthetic drug delivery system has reached the market. This Review is designed to provide a background on the challenges and requirements for the design and translation of new polymer-based delivery systems. This report will focus on chemical approaches to drug delivery for systemic applications

On-Surface Carbon Nitride Growth from Polymerization of 2,5,8-Triazido-s-heptazine

Carbon nitrides have recently come into focus for photo- and thermal catalysis, both as support materials for metal nanoparticles as well as photocatalysts themselves. While many approaches for the synthesis of three-dimensional carbon nitride materials are available, only top-down approaches by exfoliation of powders lead to thin film flakes of this inherently two-dimensional material. Here, we describe an in situ on-surface synthesis of monolayer 2D carbon nitride films, as a first step towards precise combination with other 2D materials. Starting with a single monomer precursor, we show that 2,5,8-triazido-s-heptazine (TAH) can be evaporated intact, deposited on a single crystalline Au(111) or graphite support, and activated via azide decomposition and subsequent coupling to form a covalent polyheptazine network. We demonstrate that the activation can occur in three pathways, via electrons (X-ray illumination), photons (UV illumination) and thermally. Our work paves the way to coat materials with extended carbon nitride networks which are, as we show, stable under ambient conditions