Towards Automatic Parsing of Structured Visual Content through the Use of Synthetic Data

Structured Visual Content (SVC) such as graphs, flow charts, or the like are used by authors to illustrate various concepts. While such depictions allow the average reader to better understand the contents, images containing SVCs are typically not machine-readable. This, in turn, not only hinders automated knowledge aggregation, but also the perception of displayed in-formation for visually impaired people. In this work, we propose a synthetic dataset, containing SVCs in the form of images as well as ground truths. We show the usage of this dataset by an application that automatically extracts a graph representation from an SVC image. This is done by training a model via common supervised learning methods. As there currently exist no large-scale public datasets for the detailed analysis of SVC, we propose the Synthetic SVC (SSVC) dataset comprising 12,000 images with respective bounding box annotations and detailed graph representations. Our dataset enables the development of strong models for the interpretation of SVCs while skipping the time-consuming dense data annotation. We evaluate our model on both synthetic and manually annotated data and show the transferability of synthetic to real via various metrics, given the presented application. Here, we evaluate that this proof of concept is possible to some extend and lay down a solid baseline for this task. We discuss the limitations of our approach for further improvements. Our utilized metrics can be used as a tool for future comparisons in this domain. To enable further research on this task, the dataset is publicly available at https://bit.ly/3jN1pJ

N-type Black Silicon Solar Cells

Black silicon is an interesting surface texture for solar cells because of its extremely low reflectance on a wide wavelength range and acceptance angle. In this paper we present how black silicon (b-Si) texturization can be applied on the boron doped front surface of an n-type solar cell resulting in an efficiency of 18.7%. We show that the highly boron doped emitter can be formed on black silicon without losing its good optical properties and that atomic layer deposited aluminum oxide provides good surface passivation on these boron doped b-Si emitters.Peer reviewe

Test of cold denaturation mechanism for proteins as a function of water's structure

In a recent paper [PRL 91, 138103 (2003)] a new mechanism to explain the cold denaturation of proteins, based on the loss of local low-density water structure, has been proposed. In the present paper this mechanism is tested by means of full atom numerical simulations. In good agreement with this proposal, cold denaturation resulting in the unfolded state was found at the High Density Liquid (HDL) state of water, at which the amount of open tetragonal hydrogen bonds decreases at cooling.Comment: 5 pages, 5 figure

Epitaxially grown p‐type silicon wafers ready for cell efficiencies exceeding 25%

Combining the advantages of a high‐efficiency solar cell concept and a low carbon footprint base material is a promising approach for highly efficient, sustainable, and cost‐effective solar cells. In this work, we investigate the suitability of epitaxially grown p‐type silicon wafers for solar cells with tunnel oxide passivating contact rear emitter. As a first proof of principle, an efficiency limiting bulk recombination analysis of epitaxially grown p‐type silicon wafers deposited on high quality substrates (EpiRef) unveils promising cell efficiency potentials exceeding 25% for three different base resistivities of 3, 14, and 100 Ω cm. To understand the remaining limitations in detail, concentrations of metastable defects Fe i , CrB and BO are assessed by lifetime‐calibrated photoluminescence imaging and their impact on the overall recombination is evaluated. The EpiRef wafers’ efficiency potential is tracked along the solar cell fabrication process to quantify the impact of high temperature treatments on the material quality. We observe large areas with few structural defects on the wafer featuring lifetimes exceeding 10 ms and an efficiency potential of 25.8% even after exposing the wafer to a thermal oxidation at 1050 °C

Four aspects of self-image close to death at home

Living close to death means an inevitable confrontation with one's own existential limitation. In this article, we argue that everyday life close to death embodies an identity work in progress. We used a narrative approach and a holistic-content reading to analyze 12 interviews conducted with three persons close to death. By illuminating the unique stories and identifying patterns among the participants’ narratives, we found four themes exemplifying important aspects of the identity work related to everyday life close to death. Two of the themes, named “Inside and outside of me” and “Searching for togetherness,” represented the core of the self-image and were framed by the other themes, “My place in space” and “My death and my time.” Our findings elucidate the way the individual stories moved between the past, the present, and the future. This study challenges the idea that everyday life close to impending death primarily means limitations. The findings show that the search for meaning, new knowledge, and community can form a part of a conscious and ongoing identity work close to death

Production of highly polarized [1- 13 C]acetate by rapid decarboxylation of [2- 13 C]pyruvate - application to hyperpolarized cardiac spectroscopy and imaging

Purpose: The objective of the present work was to develop and implement an efficient approach to hyperpolarize [1-13 C]acetate and apply it to in vivo cardiac spectroscopy and imaging. Methods: Rapid hydrogen peroxide induced decarboxylation was used to convert hyperpolarized [2-13 C]pyruvate into highly polarized [1-13 C]acetate employing an additional step following rapid dissolution of [2-13 C]pyruvate in a home-built multi-sample dissolution dynamic nuclear polarization system. Phantom dissolution experiments were conducted to determine optimal parameters of the decarboxylation reaction, retaining polarization and T1 of [1-13 C]acetate. In vivo feasibility of detecting [1-13 C]acetate metabolism is demonstrated using slice-selective spectroscopy and multi-echo imaging of [1-13 C]acetate and [1-13 C]acetylcarnitine in the healthy rat heart. Results: The first in vivo signal was observed ~23 s after dissolution. At the corresponding time point in the phantom experiments, 97.9 ± 0.4% of [2-13 C]pyruvate were converted into [1-13 C]acetate by the decarboxylation reaction. T1 and polarization of [1-13 C]acetate was determined to be 29.7 ± 1.9% and a 47.7 ± 0.5 s. Polarization levels of [2-13 C]pyruvate and [1-13 C]acetate were not significantly different after transfer to the scanner. In vivo, [1-13 C]acetate and [1-13 C]acetylcarnitine could be detected using spectroscopy and imaging. Conclusion: Decarboxylation of hyperpolarized [2-13 C]pyruvate enables the efficient production of highly polarized [1-13 C]acetate that is applicable to study short-chain fatty acid metabolism in the in vivo heart

High-resolution hyperpolarized metabolic imaging of the rat heart using k-t PCA and k-t SPARSE

The purpose of this work was to increase the resolution of hyperpolarized metabolic imaging of the rat heart with accelerated imaging using k–t principal component analysis (k–t PCA) and k–t compressed sensing (k–t SPARSE). Fully sampled in vivo datasets were acquired from six healthy rats after the injection of hyperpolarized [1‐13C]pyruvate. Data were retrospectively undersampled and reconstructed with either k–t PCA or k–t SPARSE. Errors of signal–time curves of pyruvate, lactate and bicarbonate were determined to compare the two reconstruction algorithms for different undersampling factors R. Prospectively undersampled imaging at 1 × 1 × 3.5‐mm3 resolution was performed with both methods in the same animals and compared with the fully sampled acquisition. k–t SPARSE was found to perform better at R < 3, but was outperformed by k–t PCA at R ≥ 4. Prospectively undersampled data were successfully reconstructed with both k–t PCA and k–t SPARSE in all subjects. No significant difference between the undersampled and fully sampled data was found in terms of signal‐to‐noise ratio (SNR) performance and metabolic quantification. Accelerated imaging with both k–t PCA and k–t SPARSE allows an increase in resolution, thereby reducing the intravoxel dephasing of hyperpolarized metabolic imaging of the rat heart

Overestimation of cardiac lactate production caused by liver metabolism of hyperpolarized [1-13C]pyruvate

PURPOSE: The purpose of this work was to study the contribution of liver [1-13 C]lactate to the lactate signal detected in the heart following injection of hyperpolarized [1-13 C]pyruvate. METHODS: A slice-selective saturation scheme was incorporated into a hybrid metabolic imaging and spectroscopy approach to selectively presaturate lactate in the liver. Imaging and slice-selective spectroscopy of [1-13 C]pyruvate and its downstream metabolites were sequentially interleaved in the same experiment with optional presaturation of liver [1-13 C]lactate. Six healthy rats were measured, and metabolic data in the heart acquired with and without presaturation of liver lactate were compared. RESULTS: When using liver lactate presaturation, a statistically significant reduction of the lactate/pyruvate ratio was observed in the spectroscopic data of the left ventricle (0.18 ± 0.03 versus 0.24 ± 0.04; p < .05) as well as in the imaging data of the blood pool (0.05 ± 0.01 versus 0.11 ± 0.01; p < .05). No significant difference in myocardial lactate was observed when using myocardium only as the region of interest in the imaging data (0.08 ± 0.01 versus 0.11 ± 0.02; p = .2). CONCLUSION: Liver metabolism leads to statistically significant overestimation of cardiac lactate production in slice-selective or nonselective spectroscopic experiments. Therefore, metabolic imaging is preferred over spectroscopy to separate left-ventricular compartments within the slice and hence avoid contamination of cardiac lactate signals. Alternatively, presaturation pulses should be used in combination with spectroscopy approach

Assessing the influence of isoflurane anesthesia on cardiac metabolism using hyperpolarized [1-13C]pyruvate

Isoflurane is a frequently used anesthetic in small‐animal dissolution dynamic nuclear polarization‐magnetic resonance imaging (DNP‐MRI) studies. Although the literature suggests interactions with mitochondrial metabolism, the influence of the compound on cardiac metabolism has not been assessed systematically to date. In the present study, the impact of low versus high isoflurane concentration was examined in a crossover experiment in healthy rats. The results revealed that cardiac metabolism is modulated by isoflurane concentration, showing increased [1‐13C]lactate and reduced [13C]bicarbonate production during high isoflurane relative to low isoflurane dose [average differences: +16% [1‐13C]lactate/total myocardial carbon, –22% [13C]bicarbonate/total myocardial carbon; +51% [1‐13C]lactate/[13C]bicarbonate]. These findings emphasize that reproducible anesthesia is important when studying cardiac metabolism. As the depth of anesthesia is difficult to control in an experimental animal setting, careful study design is required to exclude confounding factors