Light Direction Reconstruction Analysis and Improvement using XAI and CG

With rapid advances in the field of deep learning, explainable artificial intelligence (XAI) methods were introduced to gain insight into internal procedures of deep neural networks. Information gathered by XAI methods can help to identify shortcomings in network architectures and image datasets. Recent studies, however, advise to handle XAI interpretations with care, as they can be unreliable. Due to this unreliability, this study uses meta information that is produced when applying XAI to enhance the architecture – and thus the prediction performance – of a recently published regression model. This model aimed to contribute to solving the photometric registration problem in the field of augmented reality by regressing the dominant light direction in a scene. Bypassing misleading XAI interpretations, the influence of synthetic training data, generated with different rendering techniques, is further- more evaluated empirically. In conclusion, this study demonstrates how the prediction performance of the recently published model can be increased by improving the network architecture and training dataset

Occurrence of pyrrolizidine alkaloids in animal- and plant-derived food : results of a survey across Europe

Pyrrolizidine alkaloids (PAs) are secondary metabolites of plant families such as Asteraceae or Boraginaceae and are suspected to be genotoxic carcinogens. Recent investigations revealed their frequent occurrence in honey and particularly in tea. To obtain a comprehensive overview of the PA content in animal- and plant-derived food from the European market, and to provide a basis for future risk analysis, a total of 1105 samples were collected in 2014 and 2015. These comprised milk and milk products, eggs, meat and meat products, (herbal) teas, and (herbal) food supplements collected in supermarkets, retail shops, and via the internet. PAs were detected in a large proportion of plant-derived foods: 91% of the (herbal) teas and 60% of the food supplements contained at least one individual PA. All types of (herbal) teas investigated were found to contain PAs, with a mean concentration of 460 µg kg−1 dry tea (corresponding to 6.13 µg L−1 in [herbal] tea infusion). The highest mean concentrations were found in rooibos tea (599 µg kg−1 dry tea, 7.99 µg L−1 tea infusion) and the lowest in camomile tea (274 µg kg−1 dry tea, 3.65 µg L−1 tea infusion). Occurrence of PAs in food supplements was found to be highly variable, but in comparable ranges as for (herbal) tea. The highest concentrations were present in supplements containing plant material from known PA-producing plants. In contrast, only 2% of the animal-derived products, in particular 6% of milk samples and 1% of egg samples, contained PAs. Determined levels in milk were relatively low, ranged between 0.05 and 0.17 µg L−1 and only trace amounts of 0.10–0.12 µg kg−1 were found in eggs. No PAs were detected in the other animal-derived products.</p

A case of human poisoning by grayanotoxins following honey ingestion: elucidation of the toxin profile by mass spectrometry

<div><p>High-resolution mass spectrometry (HRMS) was applied for the detection of grayanotoxins (GrTx) in a contaminated honey sample. This sample was provided by a hospital due to a suspicion of intoxication after a patient had shown the typical symptoms of GrTx poisoning. Subsequent analysis proved the contamination with high amounts of GrTx and other toxins belonging to grayanane-type diterpenoids. This group of natural toxins is synthesised by the plant family Ericaceae and comprises more than 60 individual toxins, but only one compound is available as a reference standard. We applied a screening approach that easily confirms the presence or absence of GrTx without access to standards. By searching for predictable mass spectrometric fragment ions, including typical in-source fragments arising from collision-induced dissociation during electrospray ionisation, the complete toxin profile was screened and allowed the mass spectrometric identification of 15 individual GrTx. The potential of this approach is especially demonstrated by the fact that at least two of these toxins have not been previously described in the literature. A semi-quantitative estimation indicated a total toxin concentration of 358 mg kg⁻¹. An investigation of 49 honeys from the German retail market did not reveal the presence of GrTx.</p></div

Determination of pyrrolizidine alkaloids in tea, herbal drugs and honey

<div><p>Honey was previously considered to be one of the main food sources of human pyrrolizidine alkaloid (PA) exposure in Europe. However, comprehensive analyses of honey and tea sampled in the Berlin retail market revealed unexpected high PA amounts in teas. This study comprised the analysis of 87 honey as well as 274 tea samples including black, green, rooibos, melissa, peppermint, chamomile, fennel, nettle, and mixed herbal tea or fruit tea. Total PA concentrations in tea ranged from < LOD to 5647 µg kg⁻¹, while a mean value of about 10 µg kg⁻¹ was found in honey samples. Additionally, herbal drugs were investigated to identify the source of PA in teas. Results suggest that PA in tea samples are most likely a contamination caused by co-harvesting of PA-producing plants. In some cases such as fennel, anise or caraway, it cannot be excluded that these plants are able to produce PA themselves.</p></div