Showing papers by "Johannes Kepler University of Linz published in 2023"
TL;DR: The voltage-gated proton channel, HV1, is crucial for innate immune responses and the water mobility for the putative case of an uninterrupted wire is estimated in this paper .
Abstract: The voltage-gated proton channel, HV1, is crucial for innate immune responses. According to alternative hypotheses, protons either hop on top of an uninterrupted water wire or bypass titratable amino acids, interrupting the water wire halfway across the membrane. To distinguish between both hypotheses, the water mobility for the putative case of an uninterrupted wire is estimated. The predicted single-channel water permeability 2.3 × 10−12 cm3 s−1 reflects the permeability-governing number of hydrogen bonds between water molecules in single-file configuration and pore residues. However, the measured unitary water permeability does not confirm the predicted value. Osmotic deflation of reconstituted lipid vesicles reveals negligible water permeability of the HV1 wild-type channel and the D174A mutant open at 0 mV. The conductance of 1400 H+ s−1 per wild-type channel agrees with the calculated diffusion limit for a ≈2 Å capture radius for protons. Removal of a charged amino acid (D174) at the pore mouth decreases H+ conductance by reducing the capture radius. At least one intervening amino acid contributes to H+ conductance while interrupting the water wire across the membrane.
3 citations
TL;DR: In this article , the authors analyze challenges and barriers to labour-market integration of refugees in crisis and beyond, focusing on Austria and find that three areas of the pandemic's impact: on employment search processes of refugees, the effect of digitalisation of communication; and increased feelings of disorientation.
Abstract: Abstract Labour-market integration is understood as an important pillar in the successful integration processes of refugees into host societies. In the European Union at large and in Austria specifically, refugee integration processes regarding societies and the labour market have become hotly debated topics in public and scholarly debates. Focusing on Austria, this chapter analyses challenges and barriers to labour-market integration of refugees in crisis and beyond. Results from interviews with refugees indicate three areas of the pandemic’s impact: on employment search processes of refugees; the effect of digitalisation of communication; and increased feelings of disorientation.
2 citations
TL;DR: In this paper , the item count technique was shown to substantially improve the estimation accuracy and at the same time reduce the respondents' task, which can make the method a stronger and more serious competitor of the direct questioning on sensitive attributes, which is commonly used in empirical research.
Abstract: Abstract If the direct questioning on sensitive variables leads to non-ignorable item-nonresponse and untruthful answering, a considerably biased estimator might be the consequence. In such cases, indirect questioning designs, which protect the respondents’ privacy by masking the sensitive information, could pay off in terms of accuracy through an increased willingness to cooperate. To achieve this goal, such a design has to be simple in its implementation for the users and easy to understand for the respondents. In this article, it is shown for one of the indirect questioning designs, the item count technique, how the usage of specific oftentimes available prior information can substantially improve the estimation accuracy and at the same time reduce the respondents’ task. This can make the method a stronger and more serious competitor of the direct questioning on sensitive attributes, which is commonly used in empirical research.
1 citations
TL;DR: In this paper , the authors obtain the parameters for a highly and a mildly cohesive metal powder in a low-consolidated state such that they optimally reproduce lab-scale rotating-drum experiments with subsequent analysis of the material block structure.
TL;DR: In this article , a branch-and-cut-based solution algorithm was proposed for the shortest path Fortification game, in which the recourse problems correspond to (possibly NP-hard) combinatorial optimization problems.
TL;DR: In this article , a second-order cone programming (SOCP) approach is proposed to solve the problem of time-optimal path following in joint space, where the path parameter is replaced by the arc length.
Abstract: Abstract The time-optimal path following (OPF) problem is to find a time evolution along a prescribed path in task space with shortest time duration. Numerical solution algorithms rely on an algorithm-specific (usually equidistant) sampling of the path parameter. This does not account for the dynamics in joint space, that is, the actual motion of the robot, however. Moreover, a well-known problem is that large joint velocities are obtained when approaching singularities, even for slow task space motions. This can be avoided by a sampling in joint space, where the path parameter is replaced by the arc length. Such discretization in task space leads to an adaptive refinement according to the nonlinear forward kinematics and guarantees bounded joint velocities. The adaptive refinement is also beneficial for the numerical solution of the problem. It is shown that this yields trajectories with improved continuity compared to an equidistant sampling. The OPF is reformulated as a second-order cone programming and solved numerically. The approach is demonstrated for a 6-DOF industrial robot following various paths in task space.
01 Jan 2023
TL;DR: In this article , two fundamental problems in computer science related to the data type "array" are discussed: searching for an element in an array and arranging the elements in the array in a particular order (such that we may speed up subsequent searches).
Abstract: In this Arraychapter, we focus on two fundamental problems in computer science related to the data type “array”: searching for an element in an array and arranging the elements in the array in a particular order (such that we may speed up subsequent searches). In the course of our elaboration, we will also discuss the principles of formal program/algorithm verification and how they are supported in RISCAL.
TL;DR: In this article , a method for deriving a highly dynamic trajectory compliant with the system dynamics by means of solving an optimal control problem (OCP) using multiple shooting is presented.
Abstract: Abstract A robotic system constructed as a wheeled inverted pendulum (WIP) serves as an impressive demonstrator, since this kind of system is inherently nonlinear, unstable, and nonminimum phase. These properties may pose several difficulties, when it comes to control and trajectory planning. This paper shows a method for deriving a highly dynamic trajectory compliant with the system dynamics by means of solving an optimal control problem (OCP) using multiple shooting. The assumed task includes that the WIP should pass a height-restricting barrier. This can be achieved by leaning back or forth, in order to reduce the overall height of the WIP. The constraints inherent to the definition of this trajectory are nonconvex due to the shape of the robot. The constraint functions have a local minimum in an infeasible region. This can cause problems when the initial guess is within this infeasible region. To overcome this, a multistage approach is proposed for this special OCP to evade the infeasible local minimum. After solving four stages of subsequent optimization problems, the optimal trajectory is obtained and can be used as feedforward for the real system.
TL;DR: In this article , a trimetallic cobalt(II) triazole pyridine bis-[cobalt(III) corrole] complex CoIITP[CoIIIC]2 3 was applied in OER and ORR catalysis.
Abstract: As alternative energy sources are essential to reach a climate-neutral economy, hydrogen peroxide (H2O2) as futuristic energy carrier gains enormous awareness. However, seeking for stable and electrochemically selective H2O2 ORR electrocatalyst is yet a challenge, making the design of—ideally—bifunctional catalysts extremely important and outmost of interest. In this study, we explore the application of a trimetallic cobalt(II) triazole pyridine bis-[cobalt(III) corrole] complex CoIITP[CoIIIC]2 3 in OER and ORR catalysis due to its remarkable physicochemical properties, fast charge transfer kinetics, electrochemical reversibility, and durability. With nearly 100 % selective catalytic activity towards the two-electron transfer generated H2O2, an ORR onset potential of 0.8 V vs RHE and a cycling stability of 50 000 cycles are detected. Similarly, promising results are obtained when applied in OER catalysis. A relatively low overpotential at 10 mA cm−2 of 412 mV, Faraday efficiency 98 % for oxygen, an outstanding Tafel slope of 64 mV dec−1 combined with superior stability.
TL;DR: In this paper , the authors obtained an asymptotic estimate for the number of labelled 4-regular planar graphs on n vertices, where n is the radius of convergence of the generating function.
TL;DR: In this article , the authors focus on the theory of numbers, the problem of computing the greatest common divisor (gcd) of two numbers, and the ancient Euclidean algorithm that computes the gcd.
Abstract: We start with an exposition of the themes that are central to this book: mathematical theories and their theorems, computational problems in these theories, and algorithms that solve these problems. For this purpose, we shall in this chapter focus on the theory of (a certain kind of) numbers, the problem of computing the greatest common divisor (gcd) of two numbers, and the ancient Euclidean algorithm that computes the gcd.
TL;DR: The 4diac IDE as discussed by the authors is a model-based development environment for visual programming languages based on standard IEC 61131-3 and 61499, which is used in industrial control software maintenance tasks.
Abstract: Industrial control applications are usually designed by domain experts instead of software engineers. These experts frequently use visual programming languages based on standards such as IEC 61131-3 and IEC 61499. The standards apply model-based engineering concepts to abstract from hardware and low-level communication. Developing industrial control software is challenging due to the fact that control systems are usually unique and need to be maintained for many years. The arising challenges, together with the growing complexity of control software, require very usable model-based development environments for visual programming languages. However, so far only little empirical research exists on the practical usefulness of such environments, i.e., their usability and utility. In this paper, we discuss common control software maintenance tasks and tool capabilities based on existing research and show the realization of these capabilities in the 4diac IDE. We performed a walkthrough of the demonstrated capabilities using the cognitive dimensions of notations framework from the field of human–computer interaction. We then improved the tool and conducted a user study involving ten industrial automation engineers, who used the 4diac IDE in a realistic control software maintenance scenario. Based on lessons learnt from this study, we adapted the 4diac IDE to better handle large graphical models. We evaluated these changes in a reassessment study with automation engineers from seven industrial enterprises. We derive general implications with respect to large-scale applications for developers of IDEs that we deem applicable in the context of (visual) model-based engineering tools.
17 Jan 2023
TL;DR: In this paper , it was shown that the minimal discrepancy of a point set in the unit cube with respect to the BMO seminorm suffers from the curse of dimensionality, i.e., the point set suffers from dimensionality.
Abstract: We show that the minimal discrepancy of a point set in the $d$-dimensional unit cube with respect to the BMO seminorm suffers from the curse of dimensionality.
TL;DR: In this paper , an analysis of the turbulence-interface interactions during the sheet fragmentation process based on the concept of enstrophy transport across the length scales is presented, showing that the scale-dependent nature of the surface tension mechanism that interacts with the vortex stretching term and shapes the evolution of interfacial turbulence.
03 May 2023
15 May 2023
TL;DR: Kratzert et al. as discussed by the authors proposed Caravan, a globally consistent and open dataset that leverages globally available data sources that are published under an open license to derive meteorological forcings and attributes for any catchment.
Abstract: High-quality datasets are essential to support hydrological science and modeling. Several datasets exist for specific countries or regions (e.g. the various CAMELS datasets). However, these datasets lack standardization, which makes global studies difficult. Additionally, creating large-sample datasets is a time and resource consuming task, often preventing the release of data that would otherwise be open. Caravan (as in “a series of camels”) is an initiative that tries to solve both of these problems by creating an open data processing environment in the cloud for the community to use.Caravan is a globally consistent and open datasetCaravan leverages globally available data sources that are published under an open license to derive meteorological forcings and attributes for any catchment. We use ERA5-Land for meteorological forcings and hydrological reference states (SWE and four levels of soil moisture) and HydroATLAS for the catchment attributes. Currently, Caravan consists of 6830 gauges with daily streamflow data (median record length ~30 years), 9 meteorological variables (from 1981 - 2020) in different daily aggregations, 4 hydrological reference states, and a total of 221 catchment attributes.Caravan is derived entirely in the cloudAll meteorological time series (and hydrological reference states) from ERA5-Land are processed on Google Earth Engine, which removes the burden of downloading and processing large amounts of raw gridded data. Similarly, all catchment attributes are computed on Earth Engine. The code used to derive Caravan is publicly available (https://github.com/kratzert/Caravan/) . Once you have streamflow records and the corresponding catchment polygons, deriving all other data (forcing data and attributes) is a matter of a few hours of actual work. Depending on the number of catchments, their size and spatial distribution, that are being processed at once on Earth Engine , it might take a day or two for Earth Engine to extract meteorological data and catchment attributes. Most importantly: Caravan is a community projectEven though the existing data in Caravan has good coverage over most climate zones, the spatial coverage is still patchy. Here is where we see Caravan as a community effort. Given the provided code, everybody with access to streamflow data and the authorisation to redistribute it can create a Caravan extension with minimal effort and share the extension with the community, thus contributing to a dynamically growing dataset. A full step-by-step tutorial is available at https://github.com/kratzert/Caravan/wiki. We envision that, with many people participating, this will result in a truly global and spatially consistent, large-sample hydrology dataset. A first Caravan extension was already published by Julian Koch (https://zenodo.org/record/7396466), which increased the number of gauges to 7138, by adding 308 gauges in Denmark.
15 May 2023
TL;DR: Kratzert et al. as discussed by the authors built a global rainfall runoff model that does not rely on real-time measurements in the operational context but only uses globally available forcing data and globally available catchment attributes.
Abstract: The goal of Google’s Flood Forecasting Initiative is to provide timely and actionable flood warnings to everyone, globally. Until recently, Google provided operational flood warnings only for specific partner countries, namely India, Bangladesh, Sri Lanka, Colombia, and Brazil. In 2021 our flood alerting system sent out around 115 million flood notifications, reaching over 23 million people in the affected local areas. In all of the regions mentioned above, our operational model relies on partnerships with local governments to provide real-time measurements of observed discharge or water level (Nevo et al. 2021). However, relying on real-time measurement data makes it harder to scale to new regions as a) this data does not exist everywhere, and b) even if it exists, it requires significant per-country time and resource investment.Building on research results from the last few years (e.g., Kratzert et al. 2019a, Kratzert et al. 2019b, Klotz et al. 2021), we built a global rainfall-runoff model that does not rely on real-time measurements in the operational context but only uses globally available forcing data and globally available catchment attributes. It can therefore be deployed everywhere, including in ungauged basins. Following Kratzert et al. (2019a), our rainfall-runoff model is based on the Long Short-Term Memory network (LSTM) and is trained on thousands of hydrologically diverse basins from all around the world. To forecast river discharge for any given river on Earth, the model uses time series data from various meteorological forcing products (IMERG, CPC, ERA5-Land, ECMWF’s IFS), as well as static catchment characteristics.This new model allows us to scale to new regions more quickly. As of January 2023, we now provide operational flood warnings to hundreds of sites across 48 countries worldwide, with hundreds of more sites being rolled out in the coming months. Besides our previous channels of communicating flood warnings (e.g. Google Search, Google Maps, Google Alerts, and direct communications with NGOs and governments), we also released FloodHub (g.co/floodhub), a new interactive portal that allows for easy access to all operational forecasts.Here, we present more information about the modeling methodology shifts, the challenges we faced and finally showcase the latest advancements made. References:Klotz, D., et al. (2022). Uncertainty estimation with deep learning for rainfall–runoff modeling. Hydrology and Earth System Sciences, 26(6), 1673-1693.Kratzert, F., et al. (2019a). Towards learning universal, regional, and local hydrological behaviors via machine learning applied to large-sample datasets. Hydrology and Earth System Sciences, 23(12), 5089-5110.Kratzert, F., et al. (2019b). Toward improved predictions in ungauged basins: Exploiting the power of machine learning. Water Resources Research, 55(12), 11344-11354.Nevo, S., et al., (2021). Flood forecasting with machine learning models in an operational framework. Hydrology and Earth System Sciences Discussions, pp.1-31.
10 May 2023
TL;DR: This paper showed that E. coli YidC forms an ion-conducting transmembrane pore upon binding a ribosome or ribosomesnascent chain complex (RNC).
Abstract: Abstract The universally conserved protein YidC aids the insertion and folding of transmembrane polypeptides independently or as a part of the SecYEG translocon complex. In the former scenario, the lipid-exposed YidC surface equipped with a highly conserved positively charged arginine is thought to facilitate membrane insertion of the nascent chain by providing a countercharge for the acidic residues at the polypeptide’s N-terminal region. Here we show that the purified and reconstituted E. coli YidC forms an ion-conducting transmembrane pore upon binding a ribosome or ribosome-nascent chain complex (RNC). This pore is closed in the absence of ribosomes. As this pore is not visible in the published monomeric YidC structure, we used AlphaFold to construct the model of a parallel YidC dimer. Experimental evidence for a dimeric assembly comes from our BN-PAGE analysis of native vesicles, fluorescence correlation spectroscopy studies, and single-molecule fluorescence microscopy. In the dimeric model, the conserved positively charged arginine and many residues interacting with nascent chains point into the putative pore. This result suggests the possibility of an alternative mode of YidC-assisted membrane protein insertion.
TL;DR: In this paper , a toolchain is introduced to automate and to increase the efficiency of test scheduling in the automotive industry by combining common standards, which represent the road network and the test workflow, into a graph representation.
Abstract: In the automotive industry new technology has to be tested thoroughly before a market launch. In addition, many regulations hinder a short time-to-market, as well as the manually operated proving grounds (PG). Therefore, a toolchain is introduced to be able to automate and to increase the efficiency of test scheduling. Three steps are proposed. In the first step, common standards, which represent the road network and the test workflow, are converted into a graph representation. The second step combines a customer request and the collected data to a suitable base for a Vehicle Routing Problem with temporal synchronisation and skill constraints (VRPSS) for the test participants. In the third step, the VRPSS is modelled and solved by Metaheuristic methods. It is shown, that the proposed toolchain can automate the scenario concatenation for PGs.
01 Jan 2023
TL;DR: In this paper , the authors investigate the mathematical theory of sets and relations, with the special case of binary relations as sets whose elements are pairs of values, and take the opportunity to consider graph problems such as determining the reachability of nodes and the computation of shortest paths.
Abstract: In this chapter, we investigate the mathematical theory of “sets”, with the special case of binary “relations” as sets whose elements are pairs of values. Since sets and relations can model the nodes and arrows of directed “graphs”, we take the opportunity to consider graph problems such as determining the reachability of nodes and the computation of shortest paths.
04 May 2023
TL;DR: The evolutionary theory of information as mentioned in this paper is a generalization and extension of the Darwinian theory of evolution, which can be seen as a unified view of the entire evolution from the origin of life to the biological, technological, social and economic structures of the present.
Abstract: The basic concern of the general theory of evolution is to understand the entire evolution from the origin of life to the biological, technological, social, and economic structures of the present from a unified point of view and structure. The general theory of evolution can be seen as a comprehensive generalization and extension of Darwin's theory of evolution. It goes far beyond conventional extensions of Darwinian theory, such as synthetic evolutionary theory or multistage selection or evo-devo or epigenetics. Essentially, it views evolution from the perspective of the evolution of information. It expands the Darwinian terms of "biological species," "genotype," "phenotype," "mutation," and "selection" and replaces them with much more general terms. These conceptual extensions make it possible to describe evolutionary developments in quite different areas from a unified point of view and within a unified time frame.The basic idea is to understand the evolution of everything as the emergence of new information types and new information technologies in the following sense:- A new type of information is associated with the emergence of a new storage technology- For each new type of information, 3 information technologies emerge one after the other:Storage technology, Duplication technology, processing technology.With this concept, the chronology of the entire evolution can be divided in a natural way into 7 ages with 3 sub-ages each, which correspond to the 7 information types with their corresponding 3 information technologies. Better and better information technologies are the basis for the fact that more and better targeted variation mechanisms could be formed. This explains the exponential increase in the speed of development and why development is probably heading for a singular point.The following topics represent a selection of new ideas presented in detail in the paper:- Evolutionary theory of information- Link between the evolutionary theory of information and the general theory of evolution.- Megatrends of evolution- Evolution of the driving forces- Targeted variation mechanisms as essential elements of evolution- Constraints as essential elements of evolution- The illusion of free will as an evolutionary trait of success- The documentation of debt relationships (especially in the form of money) as a catalyst for win-win and cooperation mechanisms- The difference between individual utility optimization and total utility maximization- From Artificial Intelligence 1.0 to Artificial Intelligence 2.0
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TL;DR: In this article , the authors sketch the theory of propositional formulas, discuss their normal forms, and investigate the problems of minimizing a propositional formula and determining its satisfiability, where the problem of finding the satisfiability of a Boolean formula is studied.
Abstract: The subject of this chapter are propositional formulas (also called Boolean expressions). In the following, we will sketch the theory of propositional formulas, discuss their normal forms, and investigate the problems of minimizing a propositional formula and determining its satisfiability.
TL;DR: In this paper , it was shown that both of these methods can be generalized to the case of partial differential equations, this is, one can go either with the solution of tropicalized systems, or test monomial-freeness of the ideal generated by the initials when looking for supports of power series solutions of systems of differential equations.
TL;DR: In this paper , a new context-specific questionnaire was developed as a diagnostic tool to measure workers' attitudes toward mobile cooperative manufacturing robots to provide a basis for managerial decisions and interventions.
Abstract: Abstract The implementation of new robotic technology at workplaces is oftentimes accompanied by social and organizational change processes. A new context-specific questionnaire was developed as a diagnostic tool to measure workers’ attitudes toward mobile cooperative manufacturing robots to provide a basis for managerial decisions and interventions—the “Attitudes toward Cooperative Industrial Robots Questionnaire” (ACIR-Q). Two samples, an online sample of 355 German manufacturing workers and a field sample of 201 workers from 4 local manufacturing companies were collected. For a large item pool, exploratory and confirmatory factor analysis was used to identify the attitudinal factor structure. Data showed a combined affective-behavioral factor and two cognitive factors on task-related and social-related beliefs. Based on this, the 12-item short scale ACIR-Q was derived using ant colony optimization. As attitudes can also be interpreted as networks of evaluative responses, network analysis was used for further insights. The small-world network structure (high clustering and connectivity) allows to hold complex attitudes and centrality measures indicate the most influential evaluative responses. Additionally, we explored relationships between workers’ attitudes and interpersonal variables (perceived competence, perceived control, and general self-efficacy), as well as social/organizational variables (trust in management, support climate, job insecurity and job characteristics). Based on the results, practical implications are suggested to improve workers’ attitudes.
01 Jan 2023
TL;DR: In this article , two integer programming formulations for the discrete α $$ \alpha $$ -neighbor p $$ p $$ -center problem are presented, and they are further enhanced with a starting heuristic and a primal heuristic.
Abstract: The discrete α $$ \alpha $$ -neighbor p $$ p $$ -center problem (d- α $$ \alpha $$ - p $$ p $$ CP) is an emerging variant of the classical p $$ p $$ -center problem which recently got attention in literature. In this problem, we are given a discrete set of points and we need to locate p $$ p $$ facilities on these points in such a way that the maximum distance between each point where no facility is located and its α $$ \alpha $$ -closest facility is minimized. The only existing algorithms in literature for solving the d- α $$ \alpha $$ - p $$ p $$ CP are approximation algorithms and two recently proposed heuristics. In this work, we present two integer programming formulations for the d- α $$ \alpha $$ - p $$ p $$ CP, together with lifting of inequalities, valid inequalities, inequalities that do not change the optimal objective function value and variable fixing procedures. We provide theoretical results on the strength of the formulations and convergence results for the lower bounds obtained after applying the lifting procedures or the variable fixing procedures in an iterative fashion. Based on our formulations and theoretical results, we develop branch-and-cut (B&C ) algorithms, which are further enhanced with a starting heuristic and a primal heuristic. We evaluate the effectiveness of our B&C algorithms using instances from literature. Our algorithms are able to solve 116 out of 194 instances from literature to proven optimality, with a runtime of under a minute for most of them. By doing so, we also provide improved solution values for 116 instances.
TL;DR: AMon as discussed by the authors is a flexible adaptive monitoring framework that supports the specification and validation of monitoring adaptation rules, using a domain-specific language, and automatically generates code for direct deployment onto devices.