Beyond the Rating Matrix: Debiasing Implicit Feedback Loops in Collaborative Filtering

Implicit feedback collaborative filtering recommender systems suffer from exposure bias that corrupts performance and creates filter bubbles and echo chambers. Our study aims to provide a practical method that does not inherit any exposure bias from the data given the information about the user, the choice, and the choice set associated with each observation. We validated the model’s functionality and capability to reduce bias and compared it to baseline mitigation strategies by simulation. Our model inherited little to no bias, while the other approaches failed to mitigate all bias. To the best of our knowledge, we are first to identify a feasible approach to tackle exposure bias in recommender systems that does not require arbitrary parameter choices or large model extensions. With our findings, we encourage the recommender systems community to move away from rating-matrix-based towards discrete-choice-based models

Menschenwürde online verteidigen

MENSCHENWÜRDE ONLINE VERTEIDIGEN Menschenwürde online verteidigen / Darmstadt, Alina (Rights reserved) ( -

Establishing a three-dimensional scaffold model of hepatoblastoma

Introduction: Emerging technologies such as three-dimensional (3D) cell culture and the generation of biological matrices offer exciting new possibilities in disease modelling and tumour therapy. The paucity of laboratory models for hepatoblastoma (HB), the most prevalent malignant liver tumour in children, has hampered the identification of new treatment options for HB patients. We aimed to establish a reliable 3D testing platform using liver-derived scaffolds and HB cell lines that reflect the heterogeneous biology of the disease so as to allow reproducible preclinical research and drug testing.Methods: In a sequence of physical, chemical and enzymatic decellularisation techniques mouse livers were stripped off all cellular components to obtain a 3D scaffold. HB cell lines were then seeded onto these scaffolds and cultivated for several weeks.Results: Our newly generated biological scaffolds consist of liver-specific extracellular matrix components including collagen IV and fibronectin. A cultivation of HB cell lines on these scaffolds led to the formation of 3D tumour structures by infiltration into the matrix. Analyses of drug response to standard-of-care medication for HB showed reliable reproducibility of our stocked models.Discussion: Our HB models are easy-to-handle, producible at large scale, and can be cryopreserved for ready-to-use on-demand application. Our newly generated 3D HB platform may therefore represent a faithful preclinical model for testing treatment response in precision cancer medicine

PU.1 controls fibroblast polarization and tissue fibrosis

Fibroblasts are polymorphic cells with pleiotropic roles in organ morphogenesis, tissue homeostasis and immune responses. In fibrotic diseases, fibroblasts synthesize abundant amounts of extracellular matrix, which induces scarring and organ failure. By contrast, a hallmark feature of fibroblasts in arthritis is degradation of the extracellular matrix because of the release of metalloproteinases and degrading enzymes, and subsequent tissue destruction. The mechanisms that drive these functionally opposing pro-fibrotic and pro-inflammatory phenotypes of fibroblasts remain unknown. Here we identify the transcription factor PU.1 as an essential regulator of the pro-fibrotic gene expression program. The interplay between transcriptional and post-transcriptional mechanisms that normally control the expression of PU.1 expression is perturbed in various fibrotic diseases, resulting in the upregulation of PU.1, induction of fibrosis-associated gene sets and a phenotypic switch in extracellular matrix-producing pro-fibrotic fibroblasts. By contrast, pharmacological and genetic inactivation of PU.1 disrupts the fibrotic network and enables reprogramming of fibrotic fibroblasts into resting fibroblasts, leading to regression of fibrosis in several organs

Covid-19 and Ukrainian Crisis Exponentiates the Need for the Inclusion of Conflict and Disaster Medicine in Medical Curriculum

© The Author(s) 2022.Conflict medicine is an age-old branch of medicine which focuses on delivering healthcare services to the injured in the setting of conflicts, wars, disasters, and/or other calamities. The course in its purest form has been traditionally given only in military medical schools while civilian medical students are usually taught parts of the course in other overlapping subjects like surgery, infectious diseases, etc. However, in a crisis situation, civilian doctors are expected to double up as military doctors, which leads to emotional, mental, and physical stress for the civilian doctors along with logistical and organizational challenges. The current Covid-19 pandemic and the Russo-Ukrainian conflict have highlighted once again the emergent need for the implementation of conflict medicine courses in regular medical curricula, so as to make the medical students situation-ready. With our present discussion, we aim to provide a brief overview of the course, its core modules, challenges to its implementation, and possible solutions. We believe that the complex management skills gained by this course are not only useful in conflict scenario but are also valuable in managing day-to-day medical emergencies.publishersversionPeer reviewe