Screen content images typically contain a mix of natural and synthetic image parts. Synthetic sections usually are comprised of uniformly colored areas and repeating colors and patterns. In the VVC standard, these properties are exploited using Intra Block Copy and Palette Mode. In this paper, we show that pixel-wise lossless coding can outperform lossy VVC coding in such areas. We propose an enhanced VVC coding approach for screen content images using the principle of soft context formation. First, the image is separated into two layers in a block-wise manner using a learning-based method with four block features. Synthetic image parts are coded losslessly using soft context formation, the rest with VVC. We modify the available soft context formation coder to incorporate information gained by the decoded VVC layer for improved coding efficiency. Using this approach, we achieve Bjontegaard-Delta-rate gains of 4.98% on the evaluated data sets compared to VVC.

Soft context formation is a lossless image coding method for screen content. It encodes images pixel by pixel via arithmetic coding by collecting statistics for probability distribution estimation. Its main pipeline includes three stages, namely a context model based stage, a color palette stage and a residual coding stage. Each stage is only employed if the previous stage is impossible since necessary statistics, e.g. colors or contexts, have not been learned yet. We propose the following enhancements: First, information from previous stages is used to remove redundant palette entries and prediction errors in subsequent stages. Additionally, implicitly known stage decision signals are no longer explicitly transmitted. These enhancements lead to an average bit rate decrease of 1.16% on the evaluated data. Compared to FLIF and HEVC, the proposed method needs roughly 0.28 and 0.17 bits per pixel less on average for 24-bit screen content images, respectively.

Podocyte detachment due to mechanical stress is a common issue in hypertension-induced kidney disease. This study highlights the role of zyxin for podocyte stability and function. We have found that zyxin is significantly up-regulated in podocytes after mechanical stretch and relocalizes from focal adhesions to actin filaments. In zyxin knockout podocytes, we found that the loss of zyxin reduced the expression of vinculin and VASP as well as the expression of matrix proteins, such as fibronectin. This suggests that zyxin is a central player in the translation of mechanical forces in podocytes. In vivo, zyxin is highly up-regulated in patients suffering from diabetic nephropathy and in hypertensive DOCA-salt treated mice. Furthermore, zyxin loss in mice resulted in proteinuria and effacement of podocyte foot processes that was measured by super resolution microscopy. This highlights the essential role of zyxin for podocyte maintenance in vitro and in vivo, especially under mechanical stretch.

Environmental pollution is an ever-growing concern. Industrial sites as well as agricultural use areas can bear immense harmful burdens. Unintentionally improperly disposed of wastes as well as illegally dumped chemicals pose additional risks in the environment, while remains of pharmaceuticals are a regular concern in sources of drinking water. Pollutants such as PFAS and microplastics could even be detected in the most remote regions of the earth and are known for adverse effects on humans and their environment. Establishing a comprehensive overview of where pollution of which severity and with what substances occurs is thus important, so remediations can be planned and prioritized. This necessitates fast, versatile, reliable and cheap measurements, ideally directly at sampling sites.

A promising class of transducers for detecting a multitude of pollutants are DNA Quantum Clusters. QC:DNA are highly sensitive and selective transducers for many substances, showing responses in their fluorescent behaviors based on their chemical environment. Based on the specific design, QC:DNA can interact with different chemical species and exhibit tuned excitation and emission wavelengths.

For the use of such transducers, we present a fluorescence reader integrated around capillaries. The system is designed for easy and fast customization for a large range of excitation and emission wavelengths while focusing on system portability and striving for affordability. The microfluidic system controlling and performing the assay is based on droplet sequences to facilitate fast mixing while allowing for incubation times with minimal dispersion and enabling a temporary storage and a precise processing of samples.

Loosening of an artificial hip joint is a frequent complication in orthopedics and trauma surgery. Due to a lack of accuracy, conventional diagnostic methods such as projection radiography cannot reliably diagnose loosening in its early stages or detect whether it is associated with the formation of a biofilm in the bone-implant interface.

In this work, we developed an ultrasonic measurement procedure for quantifying the thickness of the layer between bone and prosthesis as a correlate to loosening. In principle, it also allows for the material characterization of the interface. An analytical model for the reflection of sound waves in a three-layer system was combined with a new data processing method to face the challenges of the specific medical application. By non-linear fitting the theoretical prediction of the model to the actual shape of the reflected sound waves in frequency domain, the thickness of the interlayer can be determined and predictions about its physical properties are possible. The presented approach was successfully applied to idealized test systems and a bone-implant system for thickness determination in the range of approx. 200 µm to 2 mm [1].

The talk will focus on the physical background and the key concepts of the procedure as well as on representative experiments, but also highlight its future potential in medical application.

[1] J. Lützelberger et al., Sensors 23, 5942 (2023)