Beyond Binary Boundaries – Exploring the Potential of Categorical Variables in Counterfactual Explanations

The rapid development of Artificial Intelligence (AI) has brought about significant changes in various industries. However, the opaqueness of AI systems leads to blind trust, distrust, or even avoidance of the systems altogether. Against this background, counterfactual explanation methods generate human-understandable explanations of how an AI system arrives at a given output. However, the thorough integration of categorical variables in the generation of counterfactual explanations remains a challenging research problem. In this paper, we investigate by means of a user study how a human-like handling of categorical variables affects users’ perception of explanations for a state-of-the-art counterfactual explanation approach. The results show that using a human-like handling of categorical variables leads to the generation of explanations preferred by users. Moreover, we find that the handling of categorical variables affects users’ perceptions of the concreteness, coherence, and relevance of the generated counterfactual explanations

Capturing Users’ Reality: A Novel Approach to Generate Coherent Counterfactual Explanations

The opacity of Artificial Intelligence (AI) systems is a major impediment to their deployment. Explainable AI (XAI) methods that automatically generate counterfactual explanations for AI decisions can increase users’ trust in AI systems. Coherence is an essential property of explanations but is not yet addressed sufficiently by existing XAI methods. We design a novel optimization-based approach to generate coherent counterfactual explanations, which is applicable to numerical, categorical, and mixed data. We demonstrate the approach in a realistic setting and assess its efficacy in a human-grounded evaluation. Results suggest that our approach produces explanations that are perceived as coherent as well as suitable to explain the factual situation

Tell Me Why (I Want It That Way) – Effects of Explanations and Online Customer Reviews on Trust in Recommender Systems

Review-based recommender systems (RS) have shown great potential in helping users manage information overload and find suitable items. However, a lack of trust still impedes the widespread acceptance of RS. To increase users’ trust, research proposes various methods to generate justifications or explanations. Furthermore, online customer reviews (OCRs) are found to be a trustworthy and reliable source of information. However, it is still unclear how justifications compare to explanations in their influence on users’ trust and whether basing them on OCRs additionally adds trust. Hence, we conduct an online experiment with 531 participants and find that explanations exceed justifications in increasing users’ trust, while basing them on OCRs directly increases users’ intentions to use the system and adopt recommendations without increasing trust in the RS themselves. Unifying different research streams from review-based RS and Explainable Artificial Intelligence, we provide an overarching, holistic view on the conception of justifications and explanations

Diversification of Camphorosmeae (Amaranthaceae s.l.) during the Miocene-Pliocene aridification of inland Australia

The Australian Camphorosmeae represent a monophyletic lineage that diversified to include ca. 150 spp. across 12 genera, and populate large parts of arid Australia. Tracking the origin and spread of this ancestrally salt and drought tolerant lineage provides additional evidence about the timing of the evolutionary history and phylogenetic assembly of arid habitats in Australia. Using a customized RADseq approach, sequence data for 104 species of the Australian Camphorosmeae representing all 12 genera were generated and included in phylogenetic and dating analyses. Furthermore, habitat type occurrences and preferences of species and clades were recorded. As suspected, the characters used to delimit current Australian Camphorosmeae genera do not support monophyletic groups, as phylogenetic analyses yielded 17 statistically supported clades across a large Maireana grade and crown radiation of Sclerolaena. The diversification of Australian Camphorosmeae is clearly linked to landscape changes and emerging new habitat types in arid Australia since the ancestral element likely arrived from temperate semi-arid to arid parts of continental Eurasia in the Middle Miocene. Migration was likely multidirectional and followed a west-to-east aridification. Crown group diversification was strongest during the Pliocene and likely promoted by the west-to-east expansion of Riverine Desert habitats and subsequent expansion and colonization of newly developing arid habitats. Rapid range expansion, fast habitat saturation, as well as periodic expansion, contraction and replacement of arid habitats, may have caused the rather species-poor clades of the earlier-divergent Maireana grade, compared to the continuously diversifying Sclerolaena clade

How to develop health-promoting food supplements by using single-use bioreactors

There is currently considerable interest in alternative and sustainable production methods for healthy foods. The cultivation of plant cell cultures in suitable bioreactors instead of growing whole plants on the field may be a solution. In this way, the cell cultures of interesting plant species can be established independent of the location. Furthermore, secondary metabolism can be specifically controlled during mass propagation of the cells. In other words, the expression of compounds promoting health and wellbeing can be supported, and the formation of substances with adverse health effects can be suppressed. We used this approach to make cacao powder and to produce a ‘cell culture chocolate’ by growing suspension cells from Theobroma cacao in a Flexsafe RM 20L bag with a screw cap from a BIOSTAT RM 20/50. The cell line (dark culture) was established from a well-growing and friable callus clone, and has a doubling time of 4 days. It provided up to 40% higher concentrations of the polyphenols epicatechine, procyanidine B1, B2 and C1, and cinnamtannine A2 than cocoa beans from pods grown in Puerto Rico. The alkaloids caffeine and theobromine were absent in the cell culture grown in MS-medium. On day 16, about 300 g biomass (fresh weight) was harvested from the wave-mixed single-use bioreactor operated in feeding mode. Addition of an antifoam agent and pH-regulator was not required. The biomass was freeze-dried, resulting in in vitro cacao powder that was roasted and milled before adding sugar, lecithin and cocoa butter. 3 blocks of dark chocolate (70%) were produced, which provided the experts on the ZHAW`s sensory panel with a unique taste experience. The flavour was intensive and complex, citric and berry flavours being predominant. The results demonstrate the suitability of wave-mixed bioreactors for the development of plant cell-based health-promoting food and food ingredients. Subsequent studies will focus on the influence of power input and shear stress on polyphenol formation, and the development of a scalable low-cost bioreactor

Behavioural and fitness effects of translocation to a novel environment: Whole‐lake experiments in two aquatic top predators

Translocation into a novel environment through common fisheries management practices, such as fish stocking, provides opportunities to study behavioural and fitness impacts of translocations at realistic ecological scales. The process of stocking, as well as the unfamiliarity with novel ecological conditions and the interactions with resident fish may affect translocated individuals, leading to alterations of behaviours and causing fitness impacts. Our objectives were to investigate how aquatic top predators behaviourally establish themselves and compete with resident individuals following introduction in a novel lake environment and to investigate the resulting fitness consequences. Using high‐resolution acoustic telemetry, we conducted whole‐lake experiments and compared the activity, activity‐space size and fate of translocated and resident individuals in two model top predators, the northern pike Esox lucius (n = 160) and European catfish Silurus glanis (n = 33). Additionally, we compared the reproductive success of translocated and resident northern pike. The experiment was conducted with large (adult) individuals of different origins, resilient to predation, but subject to agonistic interactions and competition with resident fish. Over a period of several months, the translocated catfish exhibited consistently larger activity‐space sizes than resident catfish, but did not differ from residents in activity and survival. The pike from one of the two translocated origins we tested also showed elevated space‐use, and both translocated origins revealed higher mortality rates than their resident conspecifics, indicating maladjustment to their novel environment. When non‐resident pike reproduced, they overwhelmingly produced hybrid offspring with resident fish, indicating that introductions fostered gene flow of non‐native genes. Our study indicates that fish introductions result in behavioural and fitness impacts even in large‐bodied top predators that experience low levels of natural predation risk.Leibniz CommunityBesatzfisch (German Federal Ministry for Education and Research)Peer Reviewe

Preparing for the future of work: a novel data-driven approach for the identification of future skills

The future of work is changing rapidly as result of fast technological developments, decarbonization and social upheavals. Thus, employees need a new skillset to be successful in the future workforce. However, current approaches for the identification of future skills are either based on s small sample of expert opinions or the result of researchers interpreting the results of data-driven approaches and thus not meaningful for the stakeholders. Against this background, we propose a novel process for the identification of future skills incorporating a data-driven approach with expert interviews. This enables identifying future skills that are comprehensive and representative for a whole industry and region as well as meaningful for the stakeholders. We demonstrate the applicability and utility of our process by means of a case study, where we identify 33 future skills for the manufacturing industry in Baden-Wuerttemberg, Germany. Our work contributes to the identification of comprehensive and representative future skills (for whole industries)

How challenging RADseq data turned out to favor coalescent-based species tree inference. A case study in Aichryson (Crassulaceae)

Analysing multiple genomic regions while incorporating detection and qualification of discordance among regions has become standard for understanding phylogenetic relationships. In plants, which usually have comparatively large genomes, this is feasible by the combination of reduced-representation library (RRL) methods and high-throughput sequencing enabling the cost effective acquisition of genomic data for thousands of loci from hundreds of samples. One popular RRL method is RADseq. A major disadvantage of established RADseq approaches is the rather short fragment and sequencing range, leading to loci of little individual phylogenetic information. This issue hampers the application of coalescent-based species tree inference. The modified RADseq protocol presented here targets ca. 5,000 loci of 300-600nt length, sequenced with the latest short-read-sequencing (SRS) technology, has the potential to overcome this drawback. To illustrate the advantages of this approach we use the study group Aichryson Webb & Berthelott (Crassulaceae), a plant genus that diversified on the Canary Islands. The data analysis approach used here aims at a careful quality control of the long loci dataset. It involves an informed selection of thresholds for accurate clustering, a thorough exploration of locus properties, such as locus length, coverage and variability, to identify potential biased data and a comparative phylogenetic inference of filtered datasets, accompanied by an evaluation of resulting BS support, gene and site concordance factor values, to improve overall resolution of the resulting phylogenetic trees. The final dataset contains variable loci with an average length of 373nt and facilitates species tree estimation using a coalescent-based summary approach. Additional improvements brought by the approach are critically discussed

Inter- and intra-island speciation and their morphological and ecological correlates in Aeonium (Crassulaceae), a species-rich Macaronesian radiation

Background and Aims The most species-rich and ecologically diverse plant radiation on the Canary Islands is the Aeonium alliance (Crassulaceae). In island radiations like this, speciation can take place either within islands or following dispersal between islands. Aiming at quantifying intra- and inter-island speciation events in the evolution of Aeonium, and exploring their consequences, we hypothesized that (1) intra-island diversification resulted in stronger ecological divergence of sister lineages, and that (2) taxa on islands with a longer history of habitation by Aeonium show stronger ecological differentiation and produce fewer natural hybrids. Methods We studied the biogeographical and ecological setting of diversification processes in Aeonium with a fully sampled and dated phylogeny inferred using a ddRADseq approach. Ancestral areas and biogeographical events were reconstructed in BioGeoBEARS. Eleven morphological characters and three habitat characteristics were taken into account to quantify the morphological and ecological divergence between sister lineages. A co-occurrence matrix of all Aeonium taxa is presented to assess the spatial separation of taxa on each island. Key Results We found intra- and inter-island diversification events in almost equal numbers. In lineages that diversified within single islands, morphological and ecological divergence was more pronounced than in lineages derived from inter-island diversification, but only the difference in morphological divergence was significant. Those islands with the longest history of habitation by Aeonium had the lowest percentages of co-occurring and hybridizing taxon pairs compared with islands where Aeonium arrived later. Conclusions Our findings illustrate the importance of both inter- and intra-island speciation, the latter of which is potentially sympatric speciation. Speciation on the same island entailed significantly higher levels of morphological divergence compared with inter-island speciation, but ecological divergence was not significantly different. Longer periods of shared island habitation resulted in the evolution of a higher degree of spatial separation and stronger reproductive barriers.info:eu-repo/semantics/publishedVersio

Quantitative uptake of colloidal particles by cell cultures

The use of nanotechnologies involving nano- and microparticles has increased tremendously in the recent past. There are various beneficial characteristics that make particles attractive for a wide range of technologies. However, colloidal particles on the other hand can potentially be harmful for humans and environment. Today, complete understanding of the interaction of colloidal particles with biological systems still remains a challenge. Indeed, their uptake, effects, and final cell cycle including their life span fate and degradation in biological systems are not fully understood. This is mainly due to the complexity of multiple parameters which need to be taken in consideration to perform the nanosafety research. Therefore, we will provide an overview of the common denominators and ideas to achieve universal metrics to assess their safety. The review discusses aspects including how biological media could change the physicochemical properties of colloids, how colloids are endocytosed by cells, how to distinguish between internalized versus membrane-attached colloids, possible correlation of cellular uptake of colloids with their physicochemical properties, and how the colloidal stability of colloids may vary upon cell internalization. In conclusion three main statements are given. First, in typically exposure scenarios only part of the colloids associated with cells are internalized while a significant part remain outside cells attached to their membrane. For quantitative uptake studies false positive counts in the form of only adherent but not internalized colloids have to be avoided. pH sensitive fluorophores attached to the colloids, which can discriminate between acidic endosomal/lysosomal and neutral extracellular environment around colloids offer a possible solution. Second, the metrics selected for uptake studies is of utmost importance. Counting the internalized colloids by number or by volume may lead to significantly different results. Third, colloids may change their physicochemical properties along their life cycle, and appropriate characterization is required during the different stages.This work was supported by the European Commission (grant FutureNanoNeeds) grant agreement no. 604602 to WJP. NF acknowledges funding from the Lars Hiertas Minne Fundation (Sweden), SA, BP and IC acknowledge a fellowship from the Alexander von Humboldt Fundation (Germany). AE acknowledges Junta de Andalucía (Spain) for a Talentia Postdoc Fellowship, co-financed by the European Union Seventh Framework Programme, grant agreement no 267226. AHS acknowledges the Egyptian government (Ministry of Higher Education, Mission). The project was also supported by the Dr. Dorka-Stiftung (Germany) to PJ