@article{AmorimSperaNicoaraetal.2024, author = {Amorim, Isilda and Spera, Natalia C.M. and Nicoara, Nicoleta and Ramasamy, Devaraj and Alves, Diana F. and Stollenwerk, Manfred and Stadtm{\"u}ller, Johannes and D{\"o}hring, Thorsten and Sadewasser, Sascha and Kolen'ko, Yury V. and Sousa, Juliana P.S.}, title = {Overall alkaline water electrolysis over active, stable, low loading iridium catalysts sputtered on nickel foam}, series = {International Journal of Hydrogen Energy}, volume = {92}, journal = {International Journal of Hydrogen Energy}, publisher = {Elsevier BV}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2024.10.306}, pages = {852 -- 864}, year = {2024}, subject = {Iridium}, language = {en} } @article{DobešovaGierKopecnaetal.2022, author = {Dobešov{\´a}, Lucie and Gier, Theresa and Kopecna, Olga and Pag{\´a}čov{\´a}, Eva and Vičar, Tom{\´a}š and Bestvater, Felix and Toufar, Jiř{\´i} and Bač{\´i}kov{\´a}, Alena and Kopel, Pavel and Fedr, Radek and Hildenbrand, Georg and Falkov{\´a}, Iva and Falk, Martin and Hausmann, Michael}, title = {Incorporation of Low Concentrations of Gold Nanoparticles: Complex Effects on Radiation Response and Fate of Cancer Cells}, series = {Pharmaceutics}, volume = {14}, journal = {Pharmaceutics}, number = {1}, publisher = {MDPI AG}, issn = {1999-4923}, doi = {https://doi.org/10.3390/pharmaceutics14010166}, year = {2022}, abstract = {(1) Background: In oncology research, a long-standing discussion exists about pros and cons of metal nanoparticle-enhanced radiotherapy and real mechanisms behind the tumor cell response to irradiation (IR) in presence of gold nanoparticles (GNPs). A better understanding of this response is, however, necessary to develop more efficient and safety nanoparticle (NP) types designed to disturb specific processes in tumor cells. (2) Aims and Methods: We combined 3D confocal microscopy and super-resolution single molecule localization microscopy (SMLM) to analyze, at the multiscale, the early and late effects of 10 nm-GNPs on DNA double strand break (DSB) induction and repair in tumor cells exposed to different doses of photonic low-LET (linear energy transfer) radiation. The results were correlated to different aspects of short and long-term cell viability. SkBr3 breast cancer cells (selected for the highest incidence of this cancer type among all cancers in women, and because most breast tumors are treated with IR) were incubated with low concentrations of GNPs and irradiated with 60Co γ-rays or 6 MV X-rays. In numerous post-irradiation (PI) times, ranging from 0.5 to 24 h PI, the cells were spatially (3D) fixed and labeled with specific antibodies against γH2AX, 53BP1 and H3K9me3. The extent of DSB induction, multi-parametric micro- and nano-morphology of γH2AX and 53BP1 repair foci, DSB repair kinetics, persistence of unrepaired DSBs, nanoscale clustering of γH2AX and nanoscale (hetero)chromatin re-organization were measured by means of the mentioned microscopy techniques in dependence of radiation dose and GNP concentration. (3) Results: The number of γH2AX/53BP1 signals increased after IR and an additional increase was observed in GNP-treated (GNP(+)) cells compared to untreated controls. However, this phenomenon reflected slight expansion of the G2-phase cell subpopulation in irradiated GNP(+) specimens instead of enhanced DNA damage induction by GNPs. This statement is further supported by some micro- and nano-morphological parameters of γH2AX/53BP1 foci, which slightly differed for cells irradiated in absence or presence of GNPs. At the nanoscale, Ripley's distance frequency analysis of SMLM signal coordinate matrices also revealed relaxation of heterochromatin (H3K9me3) clusters upon IR. These changes were more prominent in presence of GNPs. The slight expansion of radiosensitive G2 cells correlated with mostly insignificant but systematic decrease in post-irradiation survival of GNP(+) cells. Interestingly, low GNP concentrations accelerated DSB repair kinetics; however, the numbers of persistent γH2AX/53BP1 repair foci were slightly increased in GNP(+) cells. (4) Conclusions: Low concentrations of 10-nm GNPs enhanced the G2/M cell cycle arrest and the proportion of radiosensitive G2 cells, but not the extent of DNA damage induction. GNPs also accelerated DSB repair kinetics and slightly increased presence of unrepaired γH2AX/53BP1 foci at 24 h PI. GNP-mediated cell effects correlated with slight radiosensitization of GNP(+) specimens, significant only for the highest radiation dose tested (4 Gy).}, subject = {Strahlentherapie}, language = {en} } @article{RodenerSchaeferHausmannetal.2022, author = {Rodener, Daniel and Sch{\"a}fer, Myriam and Hausmann, Michael and Hildenbrand, Georg}, title = {Assessing the Potential for Liquid Solvents from X-ray Sources: Considerations on Bodies Orbiting Active Galactic Nuclei}, series = {Galaxies}, volume = {10}, journal = {Galaxies}, number = {5}, publisher = {MDPI AG}, issn = {2075-4434}, doi = {https://doi.org/10.3390/galaxies10050101}, year = {2022}, abstract = {We aim to establish a rough first prospect on the potential of certain biorelevant solvents (water, ammonia, and methane) being present in liquid form inside the uppermost few meters of several modeled rocky and icy surfaces of hypothetical bodies orbiting active galactic nuclei (AGNs) and investigate under which constraints this might occur. For this, we adjust and average X-ray spectra from a sample of 20 Type-1 Seyfert galaxies to calculate the mean snowline of the sample used. We then vary the hypothetical body's orbit between 10\% and 100\% of the snowline radius and calculate a sub-surface attenuation within four different model surface compositions for each. We then use this as a continuous source term for a thermal model. Example bodies are systematically investigated with sizes between 1/30 and 20 earth radii, with further variations also considered (such as possible bound rotation), to end up with a perspective of solvent phases under a wide slew of different conditions. We find that liquid solvents are possible under a multitude of parameters, with temperature being the main constraint to liquid water whereas body size and pressure are the main constraint to liquid methane and ammonia.}, subject = {L{\"o}sungsmittel}, language = {en} } @article{ErenpreisaGiulianiYoshikawaetal.2023, author = {Erenpreisa, Jekaterina and Giuliani, Alessandro and Yoshikawa, Kenichi and Falk, Martin and Hildenbrand, Georg and Salmina, Kristine and Freivalds, Talivaldis and Vainshelbaum, Ninel and Weidner, Jonas and Sievers, Aaron and Pilarczyk, G{\"o}tz and Hausmann, Michael}, title = {Spatial-Temporal Genome Regulation in Stress-Response and Cell-Fate Change}, series = {International Journal of Molecular Sciences}, volume = {24}, journal = {International Journal of Molecular Sciences}, number = {3}, publisher = {MDPI AG}, issn = {1422-0067}, doi = {https://doi.org/10.3390/ijms24032658}, year = {2023}, abstract = {Complex functioning of the genome in the cell nucleus is controlled at different levels: (a) the DNA base sequence containing all relevant inherited information; (b) epigenetic pathways consisting of protein interactions and feedback loops; (c) the genome architecture and organization activating or suppressing genetic interactions between different parts of the genome. Most research so far has shed light on the puzzle pieces at these levels. This article, however, attempts an integrative approach to genome expression regulation incorporating these different layers. Under environmental stress or during cell development, differentiation towards specialized cell types, or to dysfunctional tumor, the cell nucleus seems to react as a whole through coordinated changes at all levels of control. This implies the need for a framework in which biological, chemical, and physical manifestations can serve as a basis for a coherent theory of gene self-organization. An international symposium held at the Biomedical Research and Study Center in Riga, Latvia, on 25 July 2022 addressed novel aspects of the abovementioned topic. The present article reviews the most recent results and conclusions of the state-of-the-art research in this multidisciplinary field of science, which were delivered and discussed by scholars at the Riga symposium.}, subject = {Zellkern}, language = {en} } @article{SieversSauerBischetal.2023, author = {Sievers, Aaron and Sauer, Liane and Bisch, Marc and Sprengel, Jan and Hausmann, Michael and Hildenbrand, Georg}, title = {Moderation of Structural DNA Properties by Coupled Dinucleotide Contents in Eukaryotes}, series = {Genes}, volume = {14}, journal = {Genes}, number = {3}, publisher = {MDPI AG}, issn = {2073-4425}, doi = {https://doi.org/10.3390/genes14030755}, year = {2023}, abstract = {Dinucleotides are known as determinants for various structural and physiochemical properties of DNA and for binding affinities of proteins to DNA. These properties (e.g., stiffness) and bound proteins (e.g., transcription factors) are known to influence important biological functions, such as transcription regulation and 3D chromatin organization. Accordingly, the question arises of how the considerable variations in dinucleotide contents of eukaryotic chromosomes could still provide consistent DNA properties resulting in similar functions and 3D conformations. In this work, we investigate the hypothesis that coupled dinucleotide contents influence DNA properties in opposite directions to moderate each other's influences. Analyzing all 2478 chromosomes of 155 eukaryotic species, considering bias from coding sequences and enhancers, we found sets of correlated and anti-correlated dinucleotide contents. Using computational models, we estimated changes of DNA properties resulting from this coupling. We found that especially pure A/T dinucleotides (AA, TT, AT, TA), known to influence histone positioning and AC/GT contents, are relevant moderators and that, e.g., the Roll property, which is known to influence histone affinity of DNA, is preferably moderated. We conclude that dinucleotide contents might indirectly influence transcription and chromatin 3D conformation, via regulation of histone occupancy and/or other mechanisms.}, subject = {Genom}, language = {en} } @article{HennSieversHausmannetal.2023, author = {Henn, Lukas and Sievers, Aaron and Hausmann, Michael and Hildenbrand, Georg}, title = {Specific Patterns in Correlations of Super-Short Tandem Repeats (SSTRs) with G+C Content, Genic and Intergenic Regions, and Retrotransposons on All Human Chromosomes}, series = {Genes}, volume = {15}, journal = {Genes}, number = {1}, publisher = {MDPI AG}, issn = {2073-4425}, doi = {https://doi.org/10.3390/genes15010033}, year = {2023}, abstract = {The specific characteristics of k-mer words (2 ≤ k ≤ 11) regarding genomic distribution and evolutionary conservation were recently found. Among them are, in high abundance, words with a tandem repeat structure (repeat unit length of 1 bp to 3 bp). Furthermore, there seems to be a class of extremely short tandem repeats (≤12 bp), so far overlooked, that are non-random-distributed and, therefore, may play a crucial role in the functioning of the genome. In the following article, the positional distributions of these motifs we call super-short tandem repeats (SSTRs) were compared to other functional elements, like genes and retrotransposons. We found length- and sequence-dependent correlations between the local SSTR density and G+C content, and also between the density of SSTRs and genes, as well as correlations with retrotransposon density. In addition to many general interesting relations, we found that SINE Alu has a strong influence on the local SSTR density. Moreover, the observed connection of SSTR patterns to pseudogenes and -exons might imply a special role of SSTRs in gene expression. In summary, our findings support the idea of a special role and the functional relevance of SSTRs in the genome.}, subject = {Genom}, language = {en} } @article{Solov’yovVerkhovtsevMasonetal.2024, author = {Solov'yov, Andrey V. and Verkhovtsev, Alexey V. and Mason, Nigel J. and Amos, Richard A. and Bald, Ilko and Baldacchino, G{\´e}rard and Dromey, Brendan and Falk, Martin and Fedor, Juraj and Gerhards, Luca and Hausmann, Michael and Hildenbrand, Georg and Hrabovsk{\´y}, Miloš and Kadlec, Stanislav and Kočišek, Jaroslav and L{\´e}pine, Franck and Ming, Siyi and Nisbet, Andrew and Ricketts, Kate and Sala, Leo and Schlath{\"o}lter, Thomas and Wheatley, Andrew E. H. and Solov'yov, Ilia A.}, title = {Condensed Matter Systems Exposed to Radiation: Multiscale Theory, Simulations, and Experiment}, series = {Chemical Reviews}, volume = {124}, journal = {Chemical Reviews}, number = {13}, publisher = {American Chemical Society (ACS)}, issn = {0009-2665}, doi = {https://doi.org/10.1021/acs.chemrev.3c00902}, pages = {8014 -- 8129}, year = {2024}, abstract = {This roadmap reviews the new, highly interdisciplinary research field studying the behavior of condensed matter systems exposed to radiation. The Review highlights several recent advances in the field and provides a roadmap for the development of the field over the next decade. Condensed matter systems exposed to radiation can be inorganic, organic, or biological, finite or infinite, composed of different molecular species or materials, exist in different phases, and operate under different thermodynamic conditions. Many of the key phenomena related to the behavior of irradiated systems are very similar and can be understood based on the same fundamental theoretical principles and computational approaches. The multiscale nature of such phenomena requires the quantitative description of the radiation-induced effects occurring at different spatial and temporal scales, ranging from the atomic to the macroscopic, and the interlinks between such descriptions. The multiscale nature of the effects and the similarity of their manifestation in systems of different origins necessarily bring together different disciplines, such as physics, chemistry, biology, materials science, nanoscience, and biomedical research, demonstrating the numerous interlinks and commonalities between them. This research field is highly relevant to many novel and emerging technologies and medical applications.}, subject = {Kondensierte Materie}, language = {en} } @article{HikmatSieversHausmannetal., author = {Hikmat, Wisam Mohammed and Sievers, Aaron and Hausmann, Michael and Hildenbrand, Georg}, title = {Peculiar k-mer Spectra Are Correlated with 3D Contact Frequencies and Breakpoint Regions in the Human Genome}, series = {Genes}, volume = {15}, journal = {Genes}, number = {10}, doi = {10.3390/genes15101247}, subject = {Zellkern}, language = {de} } @article{BischoffEsenHellmann2024, author = {Bischoff, Kay and Esen, Cemal and Hellmann, Ralf}, title = {Femtosecond reductive Laser Sintering under multiple focus conditions for rapid production of conductive copper layers}, series = {Procedia CIRP}, volume = {124}, journal = {Procedia CIRP}, publisher = {Elsevier BV}, issn = {2212-8271}, doi = {http://dx.doi.org/10.1016/j.procir.2024.08.189}, pages = {629 -- 633}, year = {2024}, subject = {Femtosekundenlaser}, language = {en} } @article{BischoffMueckeSchubertetal.2024, author = {Bischoff, Kay and M{\"u}cke, Dominik and Schubert, Andreas and Esen, Cemal and Hellmann, Ralf}, title = {Rheological Investigation of Highly Filled Copper(II) Oxide Nanosuspensions to Optimize Precursor Particle Content in Reductive Laser-Sintering}, series = {Liquids}, volume = {4}, journal = {Liquids}, number = {2}, publisher = {MDPI AG}, issn = {2673-8015}, doi = {http://dx.doi.org/10.3390/liquids4020019}, pages = {382 -- 392}, year = {2024}, abstract = {In this article, the particle concentration of finely dispersed copper(II) oxide nanosuspensions as precursors for reductive laser sintering (RLS) is optimized on the basis of rheological investigations. For this metallization process, a smooth, homogeneous and defect-free precursor layer is a prerequisite for adherent and reproducible copper structures. The knowledge of the rheological properties of an ink is crucial for the selection of a suitable coating technology as well as for the adjustment of the ink formulation. Different dilutions of the nanosuspension were examined for their rheological behavior by recording flow curves. A strong shear thinning behavior was found and the viscosity decreases exponentially with increasing dilution. The viscoelastic behavior was investigated by a simulated doctor blade coating process using three-interval thixotropy tests. An overshoot in viscosity is observed, which decreases with increasing thinning of the precursor. As a comparison to these results, doctor blade coating of planar glass and polymer substrates was performed to prepare precursor layers for reductive laser sintering. Surface morphology measurements of the resulting coatings using laser scanning microscopy and rheological tests show that homogeneous precursor layers with constant thickness can be produced at a particle-solvent ratio of 1.33. A too-high particle content results in an irregular coating layer with deep grooves and a peak-to-valley height Sz of up to 7.8 μm. Precise dilution control allows the fabrication of smooth surfaces with a Sz down to 1.5 μm.}, subject = {Laserstrahlsintern}, language = {en} } @article{YangBischoffMueckeetal.2024, author = {Yang, Yongting and Bischoff, Kay and M{\"u}cke, Dominik and Esen, Cemal and Hellmann, Ralf}, title = {UV-ultrashort pulsed laser ablation of fused silica}, series = {Journal of Laser Applications}, volume = {36}, journal = {Journal of Laser Applications}, number = {1}, publisher = {Laser Institute of America}, issn = {1042-346X}, doi = {http://dx.doi.org/10.2351/7.0001197}, year = {2024}, abstract = {The authors report on ultraviolet ultrashort pulsed laser ablation of fused silica and compare the achievable micromachining results to those obtained by using the fundamental emission wavelength in infrared. Ablation in ultraviolet reveals a stable efficiency for increasing fluences, whereas using an infrared beam exhibits a decreasing trend of the ablation efficiency at higher and increasing fluences. In addition, a significant improvement in the surface quality is found by using an ultraviolet wavelength in a fluence range up to 20 J/cm2 compared to infrared, e.g., revealing an Ra of down to 0.45 μm on using the ultraviolet wavelength compared to Ra = 0.56 μm on using infrared at fluences up 15 J/cm2. Moreover, taking advantage of the high available pulse energy, the authors compare the achievable ablation efficiency and surface roughness using a conventionally focused ultraviolet beam and a defocused ultraviolet beam, finding that the defocused ultraviolet beam possesses a processing quality comparable to that of the focused beam. Finally, the authors exemplify the potential of ultraviolet ultrashort pulsed laser ablation by using a Tesla mixer for microfluidic integration of fused silica.}, subject = {Laserablation}, language = {en} } @article{MahtoMahatoChandanetal.2024, author = {Mahto, Kailash Kumar and Mahato, Bidyut and Chandan, Bikramaditya and Das, Durbanjali and Das, Priyanath and Fotis, Georgios and Vita, Vasiliki and Mann, Michael}, title = {A New Symmetrical Source-Based DC/AC Converter with Experimental Verification}, series = {Electronics}, volume = {13}, journal = {Electronics}, number = {10}, publisher = {MDPI AG}, issn = {2079-9292}, doi = {http://dx.doi.org/10.3390/electronics13101975}, year = {2024}, abstract = {This research paper introduces a new topology for multilevel inverters, emphasizing the reduction of harmonic distortion and the optimization of the component count. The complexity of an inverter is determined by the number of power switches, which is significantly reduced in the presented topology, as fewer switches require fewer driver circuits. In this proposed topology, a new single-phase generalized multilevel inverter is analyzed with an equal magnitude of voltage supply. A 9-level, 11-level, or 13-level symmetrical inverter with RL load is analyzed in MATLAB/Simulink 2019b and then experimentally validated using the dSPACE-1103 controller. The experimental verification of the load voltage and current with different modulation indices is also presented. The analysis of the proposed topology concludes that the total required number of components is lower than that necessary for the classical inverter topologies, as well as for some new proposed multilevel inverters that are also compared with the proposed topology in terms of gate driver circuits, power switches, and DC sources, which thereby enhances the goodness of the proposed topology. Thus, a comparison of this inverter with the other topologies validates its acceptance.}, subject = {Spannungswandler}, language = {en} } @article{DasMahatoChandanetal.2024, author = {Das, Durbanjali and Mahato, Bidyut and Chandan, Bikramaditya and Joshi, Hitesh and Mahto, Kailash Kumar and Das, Priyanath and Fotis, Georgios and Vita, Vasiliki and Mann, Michael}, title = {A New Cascaded Multilevel Inverter for Modular Structure and Reduced Passive Components}, series = {Electronics}, volume = {13}, journal = {Electronics}, number = {17}, publisher = {MDPI AG}, issn = {2079-9292}, doi = {http://dx.doi.org/10.3390/electronics13173566}, year = {2024}, abstract = {In high-power applications, achieving adequate power quality in power converter design is accomplished by utilizing multilevel inverters instead of using two-level and three-level inverters. The device generates a sinusoidal output voltage, which results in reduced total harmonic distortion and lower voltage stress on the switches and leads to lower electromagnetic interference, making it suitable for use in renewable energy applications. However, to illustrate the advantages mentioned above, a significant number of switching devices and DC sources are necessary while raising the voltage levels. This article proposes an asymmetrical voltage generation method, which operates in a ratio of 1:5 and generates 25 levels using 11 power switches. The topology is modular in structure, and each module has a lower component count, which significantly reduces the overall cost. The proposed topology is capable of generating negative output voltage levels without the use of an H-bridge configuration, where only three switches are used to generate any voltage levels. The functionality of the developed module is amended by fixing different voltage values in DC sources. This article also presents a comprehensive examination of the circuit and the functioning of various voltage levels. The advantages of the proposed inverter have been demonstrated by comparative research with the currently existing MLI topologies. Ultimately, both the simulation and experimental findings validated the practical capabilities.}, subject = {Mehrpunktwechselrichter}, language = {en} } @article{ArnoldKotte2024, author = {Arnold, Jessica and Kotte, Silja}, title = {Arbeitgeberattraktivit{\"a}t durch betriebliche Gesundheitsf{\"o}rderung: Eine Strategie f{\"u}r das Employer Branding?}, series = {Organisationsberatung, Supervision, Coaching}, journal = {Organisationsberatung, Supervision, Coaching}, publisher = {Springer Science and Business Media LLC}, issn = {1618-808X}, doi = {https://doi.org/10.1007/s11613-024-00911-0}, year = {2024}, abstract = {ZusammenfassungAngesichts des Arbeitskr{\"a}ftemangels investieren Unternehmen zunehmend in Employer Branding, um sich als Arbeitgeber auf dem Bewerbermarkt positiv zu positionieren. Gleichzeitig steigt das Bewusstsein f{\"u}r die Bedeutung von Gesundheit bei Einzelnen und Unternehmen. Kann daher Betriebliche Gesundheitsf{\"o}rderung (BGF) und die Kommunikation dar{\"u}ber die Arbeitgeberattraktivit{\"a}t erh{\"o}hen? In einer szenario-basierten experimentellen Online-Studie beurteilten die Studienteilnehmenden aus der Bewerber:innen-Rolle die Attraktivit{\"a}t eines Unternehmens auf Basis eines Unternehmensflyers mit vs. ohne Informationen {\"u}ber BGF-Angebote. BGF-Kommunikation hat einen positiven Effekt auf die Arbeitgeberattraktivit{\"a}t, unabh{\"a}ngig von Geschlecht, Bildungsstand und Alter. Die BGF-Kommunikation sollte vor allem authentisch, umfassend und transparent sein und etablierte Online-Kan{\"a}le nutzen.}, subject = {Personalmarketing}, language = {de} } @article{ĎuranovaSchroedelRoesner2024, author = {Ďuranov{\´a}, Lenka and Schr{\"o}del, Frank and R{\"o}sner, Marlene}, title = {Spaziergang in die Zukunft der Altenpflege: Wie Robis die Lebensqualit{\"a}t von Oldies verbessern k{\"o}nnten}, series = {Organisationsberatung, Supervision, Coaching}, volume = {31}, journal = {Organisationsberatung, Supervision, Coaching}, number = {3}, publisher = {Springer Science and Business Media LLC}, issn = {1618-808X}, doi = {https://doi.org/10.1007/s11613-024-00896-w}, pages = {389 -- 401}, year = {2024}, abstract = {In der Altenpflege herrscht Fachkr{\"a}ftemangel. Dieser beeintr{\"a}chtigt Organisationen, Personal, Pflegebed{\"u}rftige sowie Angeh{\"o}rige und erfordert innovative L{\"o}sungen. In der Berufspraxis entstand eine konkrete Forderung: Roboter, die mit den {\"A}lteren spazieren gehen. Dieser gehen wir nach. In diesem Beitrag skizzieren wir die Notwendigkeit einer Technologieinnovation in der Altenpflege aus wirtschaftspsychologischer Sicht, danach potenzielle Vorteile des begleitenden Roboters, seine Anwendungsszenarien, Hindernisse bei der Einf{\"u}hrung und die notwendigen Entwicklungsschritte. Schließlich appellieren wir an die Praxis, die Technologieentwicklung zu unterst{\"u}tzen.}, subject = {Altenpflege}, language = {de} } @article{AlvesRodriguesSallumetal.2024, author = {Alves, Caroline L. and Rodrigues, Francisco A. and Sallum, Loriz Francisco and Toutain, Thaise and Porto, Joel and Aguiar, Patricia and Thielemann, Christiane and M{\"o}ckel, Michael}, title = {Multiclass classification of Autism Spectrum Disorder, attention deficit hyperactivity disorder, and typically developed individuals using fMRI functional connectivity analysis}, series = {plos one}, volume = {2024}, journal = {plos one}, number = {19(10)}, doi = {https://doi.org/10.1371/journal.pone.0305630}, pages = {1 -- 35}, year = {2024}, abstract = {Neurodevelopmental conditions, such as Autism Spectrum Disorder (ASD) and Attention Deficit Hyperactivity Disorder (ADHD), present unique challenges due to overlapping symptoms, making an accurate diagnosis and targeted intervention difficult. Our study employs advanced machine learning techniques to analyze functional magnetic resonance imaging (fMRI) data from individuals with ASD, ADHD, and typically developed (TD) controls, totaling 120 subjects in the study. Leveraging multiclass classification (ML) algorithms, we achieve superior accuracy in distinguishing between ASD, ADHD, and TD groups, surpassing existing benchmarks with an area under the ROC curve near 98\%. Our analysis reveals distinct neural signatures associated with ASD and ADHD: individuals with ADHD exhibit altered connectivity patterns of regions involved in attention and impulse control, whereas those with ASD show disruptions in brain regions critical for social and cognitive functions. The observed connectivity patterns, on which the ML c}, subject = {Aufmerksamkeitsdefizit-Syndrom}, language = {en} } @article{SauerZindlerJumar2024, author = {Sauer, Timm and Zindler, Klaus and Jumar, Ulrich}, title = {KI-basierte Regelungskonzepte zur automatischen Spurregelung von Flurf{\"o}rderzeugen}, series = {at - Automatisierungstechnik}, volume = {72}, journal = {at - Automatisierungstechnik}, number = {4}, doi = {https://doi.org/10.1515/auto-2023-0155}, pages = {336 -- 353}, year = {2024}, abstract = {In diesem Beitrag werden zwei KI-basierte Regelungskonzepte zur automatischen Spurf{\"u}hrung von Flurf{\"o}rderzeugen (FFZ) einer heterogenen Logistikflotte vorgestellt. W{\"a}hrend die modellfreien Verfahren des best{\"a}rkenden Lernens f{\"u}r diese Anwendung als Vertreter der direkten neuronalen Regelung vorgestellt werden, l{\"a}sst sich das zweite Regelungskonzept in die Klasse der indirekten neuronalen Regelungen einordnen. Beide Konzepte zeichnen sich dadurch aus, dass sie dazu in der Lage sind, die Reglerparameter an verschiedene Varianten von FFZ anzupassen sowie vorab bekanntes Wissen bez{\"u}glich des Regelstreckenverhaltens beim Entwurf der Regler gezielt zu ber{\"u}cksichtigen.}, subject = {Flurf{\"o}rderer}, language = {de} } @article{StieglitzBurwitzDoehringetal.2022, author = {Stieglitz, Veronika and Burwitz, Vadim and D{\"o}hring, Thorsten and Hudec, Rene and Vitek, Stanislav}, title = {Design and testing of a Kirkpatrick-Baez optics variation}, series = {EPJ Web of Conferences}, volume = {266 (2022)}, journal = {EPJ Web of Conferences}, doi = {10.1051/epjconf/202226603021}, pages = {1 -- 2}, year = {2022}, abstract = {Beside Wolter I X-ray optics, which are used at most in currently operating X-ray space telescopes, there exist also other optical designs and their usability for space observations is still the matter of studies. This article covers preliminary testing results of an optical module which is based on a modified Kirkpatrick-Baez optics. This X-ray optics, consisting of four sub-modules, was assembled in Prague and tested at the PANTER test facility of MPE afterward. The sub-modules use different reflective coatings, in part developed by our research group, on complementary flat mirrors, which approximate the shape of a Kirkpatrick-Baez optical design. In this contribution we summarise the design of the optical modules, the details of applied coating layers, and the X-ray characterisation results at the PANTER test facility}, subject = {R{\"o}ntgenoptik}, language = {en} } @article{Roetzel2024, author = {R{\"o}tzel, Peter}, title = {The role of supplier-induced demand on the occurrence of information overload in managerial reporting environments}, series = {PLOS ONE}, volume = {19}, journal = {PLOS ONE}, number = {7}, doi = {https://doi.org/10.1371/journal.pone.0307671}, pages = {e0307671 -- e0307671}, year = {2024}, abstract = {This article develops a model showing how information reporters influence information load among decision makers and generate supplier-induced information demand (SID). The intra-corporate information-providing process is an expert market with information asymmetry. I show that information overload occurs as an SID and is the result of informational overconsumption deliberately caused by the supplying reporter. My analysis highlights that the information overload depends on the specificity of information. It also shows that the decision maker may face a hold-up situation in light of switching costs. The more specific the information needed, the higher the threat of information overload. The strategic content of information tempts reporting managers to overload the decision maker for the purpose of increasing their reporting transfer price and to discourage the decision maker from getting the information from another reporting manager. Although the decision maker knows a part of the information demand, information overload involves the cost of using unnecessary inputs, information overload occurs as an SID of information, even if other competing reporting managers exist. My analysis demonstrates that information overload can occur due to uncertainty and opportunism of both the decision maker and reporting managers.}, subject = {Controlling}, language = {en} } @article{SallumAlvesThielemannetal.2024, author = {Sallum, Loriz Francisco and Alves, Caroline L. and Thielemann, Christiane and Rodrigues, Francisco A.}, title = {Revealing patterns in major depressive disorder with machine learning and networks}, series = {medrxiv}, volume = {2024}, journal = {medrxiv}, number = {1}, doi = {doi.org/10.1101/2024.06.07.24308619}, pages = {1 -- 17}, year = {2024}, abstract = {Major depressive disorder (MDD) is a multifaceted condition that affects millions of people worldwide and is a leading cause of disability. There is an urgent need for an automated and objective method to detect MDD due to the limitations of traditional diagnostic approaches. In this paper, we propose a methodology based on machine and deep learning to classify patients with MDD and identify altered functional connectivity patterns from EEG data. We compare several connectivity metrics and machine learning algorithms. Complex network measures are used to identify structural brain abnormalities in MDD. Using Spearman correlation for network construction and the SVM classifier, we verify that it is possible to identify MDD patients with high accuracy, exceeding literature results. The SHAP (SHAPley Additive Explanations) summary plot highlights the importance of C4-F8 connections and also reveals dysfunction in certain brain areas and hyperconnectivity in others. Despite the lower performance of the complex network measures for the classification problem, assortativity was found to be a promising biomarker. Our findings suggest that understanding and diagnosing MDD may be aided by the use of machine learning methods and complex networks.}, subject = {Depression}, language = {en} } @article{SzewczykMoniciThielemann2024, author = {Szewczyk, Nathaniel J. and Monici, Monica and Thielemann, Christiane}, title = {How to obtain an integrated picture of the molecular networks involved in adaptation to microgravity in different biological systems?}, series = {npj Microgravity}, volume = {2024}, journal = {npj Microgravity}, number = {10}, doi = {DOI: 10.1038/s41526-024-00395-3}, pages = {1 -- 5}, year = {2024}, abstract = {Periodically, the European Space Agency (ESA) updates scientific roadmaps in consultation with the scientific community. The ESA SciSpacE Science Community White Paper (SSCWP) 9, "Biology in Space and Analogue Environments", focusses in 5 main topic areas, aiming to address key community-identified knowledge gaps in Space Biology. Here we present one of the identified topic areas, which is also an unanswered question of life science research in Space: "How to Obtain an Integrated Picture of the Molecular Networks Involved in Adaptation to Microgravity in Different Biological Systems?" The manuscript reports the main gaps of knowledge which have been identified by the community in the above topic area as well as the approach the community indicates to address the gaps not yet bridged. Moreover, the relevance that these research activities might have for the space exploration programs and also for application in industrial and technological fields on Earth is briefly discussed.}, subject = {Weltraumforschung}, language = {en} } @article{LutzHelmTschirpkeetal.2023, author = {Lutz, Christian and Helm, Jonas and Tschirpke, Katrin and Esen, Cemal and Hellmann, Ralf}, title = {Drilling Sequence Optimization Using Evolutionary Algorithms to Reduce Heat Accumulation for Femtosecond Laser Drilling with Multi-Spot Beam Profiles}, series = {MDPI Materials}, volume = {2023}, journal = {MDPI Materials}, number = {16/5775}, doi = {10.3390/ma16175775}, pages = {1 -- 12}, year = {2023}, abstract = {We report on laser drilling borehole arrays using ultrashort pulsed lasers with a particular focus on reducing the inadvertent heat accumulation across the workpiece by optimizing the drilling sequence. For the optimization, evolutionary algorithms are used and their results are verified by thermal simulation using Comsol and experimentally evaluated using a thermal imaging camera. To enhance process efficiency in terms of boreholes drilled per second, multi-spot approaches are employed using a spatial light modulator. However, as higher temperatures occur across the workpiece when using simultaneous multi-spot drilling as compared to a single-spot process, a subtle spatial distribution and sequence of the multi-spot approach has to be selected in order to limit the resulting local heat input over the processing time. Different optimization approaches based on evolutionary algorithms aid to select those drilling sequences which allow for the combination of a high efficiency of multi-spot profiles, a low-generated process temperature and a high-component quality. In particular, using a 4 x 4 laser spot array allows for the drilling of 40,000 boreholes in less than 76 s (526 boreholes/s) with a reduced temperature increase by about 35\%, as compared to a single spot process when employing an optimized drilling sequence.}, subject = {Laserbohren}, language = {en} } @article{LutzSchwarzMarxetal.2023, author = {Lutz, Christian and Schwarz, Simon and Marx, Jan and Esen, Cemal and Hellmann, Ralf}, title = {Multi-Bessel Beams Generated by an Axicon and a Spatial Light Modulator for Drilling Applications}, series = {MDPI Photonics}, volume = {2023}, journal = {MDPI Photonics}, number = {10/413}, doi = {10.3390/photonics10040413}, pages = {1 -- 9}, year = {2023}, abstract = {We report on an optical setup to generate multi-Bessel beam profiles combining a refractive axicon and a spatial light modulator. Based on their particular beam profile, Bessel beams offer advantageous properties for micro drilling processes and internal volume processing, especially for transparent materials. In addition, the laser power of industrial, ultrashort pulsed lasers has increased significantly over the last few years, offering the possibility for highly efficient processes using multi-spot profiles. Our optical concept combines the dynamic possibilities of beam splitting using a spatial light modulator with the benefits of Bessel beams, which facilitates multi-Bessel beam processing. Beside the simulation and experimental evaluation of the generated multi-Bessel beams, we exemplify the applicability of the developed module for the perforation of thin metal foils by micro drilling.}, subject = {Bessel-B{\"u}ndel}, language = {en} } @article{SommerEsenHellmann2023, author = {Sommer, David and Esen, Cemal and Hellmann, Ralf}, title = {Static and Dynamic Mechanical Behaviour of Hybrid-PBF-LB/M-Built and Hot Isostatic Pressed Lattice Structures}, series = {Mechanical Properties of Polymeric, Metallic, and Composite Materials}, volume = {16}, journal = {Mechanical Properties of Polymeric, Metallic, and Composite Materials}, number = {9}, doi = {https://doi.org/10.3390/ma16093556}, pages = {1 -- 14}, year = {2023}, abstract = {We report on a comprehensive study of the mechanical properties of maraging steel body-centred cubic lattice structures fabricated by a hybrid additive manufacturing technology that combines laser powder bed fusion with in situ high-speed milling. As the mechanical properties of additive manufactured components are inferior to, e.g., cast components, surface modifications can improve the mechanical behaviour. Different hybrid additive manufacturing technologies have been designed using additive and subtractive processes, improving process quality. Following this, mechanical testing is performed with respect to static tensile properties and dynamic stress, hardness, and porosity, comparing specimens manufactured by laser powder bed fusion only to those manufactured by the hybrid approach. In addition, the influence of different heat-treatment techniques on the mechanical behaviour of the lattice structures is investigated, namely solution and aging treatment as well as hot isostatic pressing. Thus, the influence of the superior surface quality due to the hybrid approach is evaluated, leading to, e.g., an offset of about 14-16\% for the static testing of HIP lattice structures. Furthermore, the dynamic load behaviour can be improved with a finished surface, heading to a shift of the different zones of fatigue behaviour in the testing of hybrid-built specimens.}, subject = {Isostatisches Heißpressen}, language = {de} } @article{FlachsZhukovZechetal.2024, author = {Flachs, Dennis and Zhukov, Sergey and Zech, Isabella and Schreck, Timo and Belle, Stefan and Seggern, Heinz von and Kupnik, Mario and Altmann, Alexander Anton and Thielemann, Christiane}, title = {Enzymatic Self-Degradable PLA-Based Electrets}, series = {Journal of Polymers and the Environment}, volume = {2024}, journal = {Journal of Polymers and the Environment}, number = {1}, doi = {Journal of https://doi.org/10.1007/s10924-024-03240-6}, pages = {1 -- 11}, year = {2024}, abstract = {In recent years, the demand for sustainable and degradable materials and electronic devices has increased significantly. Among a range of biodegradable polymers, poly(lactic acid) (PLA) is a good alternative to conventional petrol-based polymers because of its attractive mechanical properties and its easy processability. Recently, PLA has also been described as a promising dielectric material with piezoelectric and electret properties. We expect that PLA—after further optimization— will play an important role as a material for environmentally friendly sensors in the future, where first applications such as air filters and pressure sensors have already been proposed. However, degradation under normal ambient conditions is very slow, and an accelerated and controllable degradation process is highly desirable for any type of PLA-based sensors. Enzymatic hydrolysis with embedded enzymes has been proposed as an approach to accelerate and control degradation. In this work, we investigate the properties of PLA in terms of dielectric and mechanical properties with a focus on its ability to store charges after the enzyme proteinase K (Trit. album) has been incorporated. Results reveal that proteinase K has a positive effect on the charge stability of solvent-cast PLA electrets after complete evaporation of the solvent. Furthermore, we observed a concentration-dependent acceleration of mass loss in a Tris-HCl buffer. A fast degradation within only one day occurred at a concentration of 6 wt\% proteinase K.}, subject = {Biologisch abbaubarer Kunststoff}, language = {en} } @article{BalleisWagner1998, author = {Balleis, Kristina and Wagner, Stefan}, title = {Haftung f{\"u}r Wildsch{\"a}den in gemeinschaftlichen Jagdbezirken}, series = {Zeitschrift f{\"u}r Jagdwissenschaft}, volume = {44}, journal = {Zeitschrift f{\"u}r Jagdwissenschaft}, number = {Juni}, pages = {85 -- 93}, year = {1998}, subject = {Jagdrecht}, language = {de} } @article{Balleis2000, author = {Balleis, Kristina}, title = {Keine Heilbarkeit eines Mangels unzureichender interkommunaler Abstimmung im erg{\"a}nzenden Verfahren nach \S215 a BauGB, Urteilsbesprechung}, series = {Verwaltungsrecht f{\"u}r die Anwaltspraxis}, volume = {2000}, journal = {Verwaltungsrecht f{\"u}r die Anwaltspraxis}, number = {6}, pages = {192 -- 192}, year = {2000}, subject = {Deutschland, Baugesetzbuch}, language = {de} } @article{Balleis2000, author = {Balleis, Kristina}, title = {Rechtswidrigkeit einer Vorkaufssatzung zur Sicherung st{\"a}dtebaulicher Entwicklung, Urteilsbesprechung}, series = {Verwaltungsrecht f{\"u}r die Anwaltspraxis}, volume = {2000}, journal = {Verwaltungsrecht f{\"u}r die Anwaltspraxis}, number = {5}, pages = {155 -- 155}, year = {2000}, subject = {Stadtentwicklung}, language = {de} } @article{Balleis1997, author = {Balleis, Kristina}, title = {Zul{\"a}ssigkeit und Notwendigkeit einer landesgesetzlichen Verbandsklage im Wasserrecht}, series = {Recht der Natur / Schnellbrief}, volume = {1997}, journal = {Recht der Natur / Schnellbrief}, number = {47}, pages = {18 -- 19}, year = {1997}, subject = {Verbandsklage}, language = {de} } @article{GvozdovskyyBratovaKazantsevaetal.2023, author = {Gvozdovskyy, Igor and Bratova, Daria and Kazantseva, Z. and Malyuta, S. and Lytvyn, Petro and Schwarz, Simon and Hellmann, Ralf}, title = {Light-controllable hybrid aligning layer based on LIPSS on sapphire surface and PVCN-F film}, series = {Journal of Molecular Liquids}, volume = {387}, journal = {Journal of Molecular Liquids}, number = {keine}, doi = {10.1016/j.molliq.2023.122623}, pages = {122623 -- 122623}, year = {2023}, abstract = {The creation of aligning layers for the uniform orientation of liquid crystals is significant for both research and the application of liquid crystals. For all applications, the creation of aligning layers possessing controllable characteristics such as azimuthal and polar anchoring energies, easy-axis of director alignment and pretilt angle, in the same way as it is achieved by using photoaligning layers processed by light, is very important. Here, aligning properties of hybrid aligning layers created on the basis of sapphire surfaces additionally coated by photoaligning layer of PVCN-F are studied. These hybrid layers possess the properties of the nano-structured sapphire layer and the photosensitive PVCN-F layer, and complement each other. The irradiation time dependence of the azimuthal anchoring energy of the hybrid layers is studied. By using certain experimental conditions during irradiation of hybrid layers, e.g., polarization of light and irradiation time, a minimum value of the azimuthal anchoring energy, close to zero, was obtained. Atomic force microscope studies of the irradiated hybrid layers were also carried out. It was found that the behavior of the contact angle of nematic droplets placed on treated sapphire surfaces are in good agreement with properties of hybrid aligning layers and parameters of structuring surface obtained from AFM images.}, subject = {Fl{\"u}ssigkristall}, language = {de} } @article{HaefnerBischoffHelmetal.2023, author = {H{\"a}fner, Tom and Bischoff, Kay and Helm, Jonas and Kunz, Tim and Rung, Stefan and Esen, Cemal and Hellmann, Ralf}, title = {Picosecond laser microvia drilling of ABF material using MHz burst mode}, series = {Materials Research Express}, volume = {10}, journal = {Materials Research Express}, number = {9}, pages = {096301 -- 096311}, year = {2023}, abstract = {We report on a comprehensive study of laser percussion microvia drilling of Ajinomoto build-up film (ABF) material using an ultrashort pulsed laser in MHz burst mode. After laser processing, microvia drilling quality is being evaluated by the fabricated diameter and taper using laser scanning microscopy and metallography. The influences of the incubation effect, heat accumulation and shielding effects as a result of pulse to pulse interactions are being discussed on the ablation threshold, penetration depth and laser microvia drilling quality. We find that an increasing heat accumulation in MHz burst mode processing is responsible for the void formation and delamination of the insulating ABF layer. Therefore, the parameter clearance is introduced to evaluate these effects on the microvia sidewalls. For a comparable clearance, applying 2 intra-burst pulses achieves an average reduced taper of down to 19.5\% compared to single pulse mode. At the same time, a reduced laser drilling time of 16.7\% per microvia highlights the enormous potential of the MHz burst mode for laser drilling of ABF material in printed circuit board fabrication.}, subject = {Ultrakurzzeitlaser}, language = {en} } @article{ZettlEsenHellmann2023, author = {Zettl, Julian and Esen, Cemal and Hellmann, Ralf}, title = {Fundamental Considerations and Analysis of the Energy Distribution in Laser Turning with Ultrashort Laser Pulses}, series = {mdpi Micromachines}, volume = {14}, journal = {mdpi Micromachines}, number = {10}, doi = {10.3390/mi14101838}, pages = {1 -- 15}, year = {2023}, abstract = {This article discusses the process of the laser turning of rotational symmetric, cylindrical components using ultrashort laser pulses with respect to the geometrical conditions and the resulting energy distribution during the laser turning process. As a result, process predictions and potential process optimizations are feasible. Particular attention is drawn to the laser spot formation on the cylindrical surface of the work piece in conjunction with the positioning of the laser beam relative to the rotation axis of the specimen. Based on fundamental calculations and experimental results, an optimum processing strategy is discussed, whereat the use of a trepanning optic in the laser turning process and the forming of a particular surface structure is additionally being issued.}, subject = {Ultrakurzzeitlaser}, language = {en} } @article{DobrovolskijStark2024, author = {Dobrovolskij, Dascha and Stark, Hans-Georg}, title = {Synthetic demand data generation for individual electricity consumers: Inpainting}, series = {Energy and AI}, volume = {15}, journal = {Energy and AI}, number = {Januar 2024}, pages = {100312 -- 100320}, year = {2024}, abstract = {In this contribution we deal with the problem of producing "reasonable" data, when considering recorded energy consumption data, which are at certain sections incomplete and/or erroneous. This task is important, when energy providers employ prediction models for expected energy consumption, which are based on past recorded consumption data, which then of course should be reliable and valid. In a related contribution Yilmaz (2022), GAN-based methods for producing such "artificial data" have been investigated. In this contribution, we describe an alternative and complementary method based on signal inpainting, which has been successfully applied to audio processing Lieb and Stark (2018). After giving a short overview of the theory of proximity-based convex optimization, we describe and adapt an iterative inpainting scheme to our problem. The usefulness of this approach is demonstrated by analyzing real-world-data provided by a German energy supplier.}, subject = {Energieverbrauch}, language = {en} } @article{LiebKnopp2021, author = {Lieb, Florian and Knopp, Tobias}, title = {A wavelet-based sparse row-action method for image reconstruction in magnetic particle imaging}, series = {Medical Physics}, volume = {48}, journal = {Medical Physics}, number = {7}, pages = {3893 -- 3903}, year = {2021}, abstract = {Purpose Magnetic particle imaging (MPI) is a preclinical imaging technique capable of visualizing the spatio-temporal distribution of magnetic nanoparticles. The image reconstruction of this fast and dynamic process relies on efficiently solving an ill-posed inverse problem. Current approaches to reconstruct the tracer concentration from its measurements are either adapted to image characteristics of MPI but suffer from higher computational complexity and slower convergence or are fast but lack in the image quality of the reconstructed images. Methods In this work we propose a novel MPI reconstruction method to combine the advantages of both approaches into a single algorithm. The underlying sparsity prior is based on an undecimated wavelet transform and is integrated into a fast row-action framework to solve the corresponding MPI minimization problem. Results Its performance is numerically evaluated against a classical FISTA (Fast Iterative Shrinkage-Thresholding Algorithm) approach on simulated and real MPI data. The experimental results show that the proposed method increases image quality with significantly reduced computation times. Conclusions In comparison to state-of-the-art MPI reconstruction methods, our approach shows better reconstruction results and at the same time accelerates the convergence rate of the underlying row-action algorithm.}, subject = {Wavelet}, language = {en} } @article{BischoffEsenHellmann2023, author = {Bischoff, Kay and Esen, Cemal and Hellmann, Ralf}, title = {Preparation of Dispersed Copper(II) Oxide Nanosuspensions as Precursor for Femtosecond Reductive Laser Sintering by High-Energy Ball Milling}, series = {Nanomaterials}, volume = {13}, journal = {Nanomaterials}, number = {19}, doi = {https://doi.org/10.3390/nano13192693}, pages = {2693 -- 2693}, year = {2023}, abstract = {This contribution demonstrates and discusses the preparation of finely dispersed copper(II) oxide nanosuspensions as precursors for reductive laser sintering (RLS). Since the presence of agglomerates interferes with the various RLS sub-processes, fine dispersion is required, and oversized particles must be identified by a measurement methodology. Aside from the established method of scanning electron microscopy for imaging individual dried particles, this work applies the holistic and statistically more significant laser diffraction in combination with dynamic image analysis in wet dispersion. In addition to direct ultrasonic homogenization, high-energy ball milling is introduced for RLS, to produce stable nanosuspensions with a high fine fraction, and, above all, the absence of oversize particles. Whereas ultrasonic dispersion stagnates at particle sizes between 500 nm and 20 μm, even after 8 h, milled suspension contains a high proportion of finest particles with diameters below 100 nm, no agglomerates larger than 1 μm and a trimodal particle size distribution with the median at 50 nm already, after 100 min of milling. The precursor layers produced by doctor blade coating are examined for their quality by laser scanning microscopy. The surface roughness of such a dry film can be reduced from 1.26 μm to 88 nm by milling. Finally, the novel precursor is used for femtosecond RLS, to produce homogeneous, high-quality copper layers with a sheet resistance of 0.28 Ω/sq and a copper mass concentration of 94.2\%.}, subject = {Laserstrahlsintern}, language = {en} } @article{BischoffKeferWienkeetal.2023, author = {Bischoff, Kay and Kefer, Stefan and Wienke, Alexander and Overmeyer, Ludger and Kaierle, Stefan and Esen, Cemal and Hellmann, Ralf}, title = {Integration of Bragg gratings in aerosol-jetted polymer optical waveguides for strain monitoring capabilities}, series = {Optics Letters}, volume = {48}, journal = {Optics Letters}, number = {7}, doi = {https://doi.org/10.1364/OL.481801}, pages = {1778 -- 1781}, year = {2023}, abstract = {We demonstrate and discuss the integration of Bragg gratings in aerosol-jetted polymer optical waveguides, produced in the optical assembly and connection technology for component-integrated bus systems (OPTAVER) process. By using a femtosecond laser and adaptive beam shaping, an elliptical focal voxel generates different types of single pulse modification by nonlinear absorption in the waveguide material, which are arranged periodically to form Bragg gratings. Integration of a single grating structure or, alternatively, an array of Bragg grating structures in the multimode waveguide yields a pronounced reflection signal with typical multimodal properties, i.e., a number of reflection peaks with non-Gaussian shapes. However, the main wavelength of reflection, located around 1555 nm, is evaluable by means of an appropriate smoothing algorithm. When loaded by mechanical bending, a pronounced Bragg wavelength shift of this reflected peak up to 160 pm is detected. This demonstrates that the additively manufactured waveguides can be used not only for signal transmission but also as a sensor.}, subject = {Bragg-Reflektor}, language = {de} } @article{BischoffMueckeRothetal.2022, author = {Bischoff, Kay and M{\"u}cke, Dominik and Roth, Gian-Luca and Esen, Cemal and Hellmann, Ralf}, title = {UV-Femtosecond-Laser Structuring of Cyclic Olefin Copolymer}, series = {Polymers}, volume = {14}, journal = {Polymers}, number = {14}, doi = {https://doi.org/10.3390/polym14142962}, pages = {2962 -- 2962}, year = {2022}, abstract = {We report on the laser ablation of cyclic olefin copolymer using an amplified ultrashort pulsed laser in the ultraviolet spectral range. In addition to a high ablation depth per laser-structured layer up to 74 μm at a fluence of 22 J cm-2, an excellent mean roughness 𝑅𝑎 of laser-patterned surfaces down to 0.5 μm is demonstrated. Furthermore, with increasing fluence, increasing ablation efficiencies up to 2.5 mm3 W-1 min-1 are determined. Regarding the quality of the ablation, we observed steep ablation flanks and low debris formation, though for fluences above 10.5 J cm-2 the formation of troughs was observed, being attributed to multiple reflections on the ablation flanks. For comparison, laser ablation was performed under identical conditions with an infrared laser wavelength. The results highlight that UV ablation exhibits significant advantages in terms of ablation efficiency, surface roughness and quality. Moreover, our results show that a larger UV focus spot accelerates the ablation process with comparable quality, paving the way for high-power UV ultrashort pulsed lasers towards an efficient and qualitative tool for the laser machining of cyclic olefin copolymer. The production of complex microfluidics further underlines the suitability of this type of laser.}, subject = {Femtosekundenlaser}, language = {en} } @article{FranzYangMicheletal.2023, author = {Franz, Daniel and Yang, Yongting and Michel, Luis and Esen, Cemal and Hellmann, Ralf}, title = {Evaluation of an ultrashort pulsed laser robot system for flexible and large-area micromachining}, series = {Journal of Laser Applications}, volume = {35}, journal = {Journal of Laser Applications}, number = {4}, pages = {042057 -- 042065}, year = {2023}, abstract = {We report for the first time on the realization, characterization and application of an ultrashort pulsed laser robot system for flexible and large-area 2D and 3D laser micromachining with 6 articulated axes. To characterize the dynamic positioning of the laser beam during and after axes movement, CMOS image sensors were integrated into the beam path. A method introduced for the alignment of the optical axes allows a reduction of the deviations in laser beam positioning to less than 141.8 ± 92.9 μm within a 110° rotation range of axis 4. In addition, a high laser beam positioning repeatability of less than 102.2 μm is demonstrated over a total period of 14 h for a movement of axis 5 within a range of 0° to 90°. Initial laser cutting, laser structuring and laser marking applications on automotive dashboards and glass substrates are presented for flexible and large area 2D and 3D manufacturing. By applying a special laser cutting strategy for processing AF 32 eco thin glass, high cutting quality is achieved with a taper of up to 96.3\% without the generation of cracks, demonstrating the innovative potential of the high-precision laser robot system. Nonetheless, different identified inherent influences of each axis 1-5 during robot axis movement demand for an innovative beam stabilization concept to achieve high precision in laser beam positioning.}, subject = {Ultrakurzzeitlaser}, language = {en} } @article{RaiynWeidl2024, author = {Raiyn, Jamal and Weidl, Galia}, title = {Predicting Autonomous Driving Behavior through Human Factor Considerations in Safety-Critical Events}, series = {Smart Cities}, volume = {7}, journal = {Smart Cities}, number = {1}, doi = {https://doi.org/10.3390/ smartcities7010018}, pages = {460 -- 474}, year = {2024}, abstract = {This paper investigates the ability of autonomous driving systems to predict outcomes by considering human factors like gender, age, and driving experience, particularly in the context of safety-critical events. The primary objective is to equip autonomous vehicles with the capacity to make plausible deductions, handle conflicting data, and adjust their responses in real-time during safety-critical situations. A foundational dataset, which encompasses various driving scenarios such as lane changes, merging, and navigating complex intersections, is employed to enable vehicles to exhibit appropriate behavior and make sound decisions in critical safety events. The deep learning model incorporates personalized cognitive agents for each driver, considering their distinct preferences, characteristics, and requirements. This personalized approach aims to enhance the safety and efficiency of autonomous driving, contributing to the ongoing development of intelligent transportation systems. The efforts made contribute to advancements in safety, efficiency, and overall performance within autonomous driving systems. To describe the causal relationship between external factors like weather conditions and human factors, and safety-critical driver behaviors, various data mining techniques can be applied. One commonly used method is regression analysis. Additionally, correlation analysis is employed to reveal relationships between different factors, helping to identify the strength and direction of their impact on safety-critical driver behavior. Keywords: car following; decision making; driving behavior; naturalistic driving studies; safety-critical events; cognitive vehicles 1. Introduction Despite the increasing prevalence of vehicle automation, the persistently high number of car crashes remains a concern. Safety-critical events in human-driven scenarios have become more intricate and partially uncontrollable due to unforeseen circumstances. Investigating human driving behavior is imperative to establish traffic baselines for mixed traffic, encompassing traditional, automated, and autonomous vehicles (AVs). Various factors, such as weather conditions affecting visibility in longitudinal car-following (CF) behavior [1,2], influence human driving behavior [3]. Car-following behavior, illustrating how a following vehicle responds to the lead vehicle in the same lane, is a crucial aspect. Existing car-following models often make assumptions about homogeneous drivers, neglecting significant heterogeneity in driving experience, gender, character, emotions, and sociological, psychological, and physiological traits. Failing to account for this heterogeneity hampers a comprehensive understanding of car-following behavior, limiting model accuracy and applicability. In the development of more realistic car-following models for mixed traffic, acknowledging the diversity among drivers is crucial. By including individual variations such as risk-taking tendencies, reaction times, decision-making processes, and driving styles, the modeling of real-world driving complexities can be improved. Simplifying drivers into a few categories overlooks the richness and variety of their characteristics, prompting the need for a more comprehensive approach to capture nuances within different driver profiles. To address these Smart Cities}, subject = {Autonomes Fahrzeug}, language = {en} } @article{KeferLimbachPapeetal.2024, author = {Kefer, Stefan and Limbach, Tobias and Pape, Natalie and Klamt, Kathrin and Schmauss, Bernhard and Hellmann, Ralf}, title = {Birefringence in Injection-Molded Cyclic Olefin Copolymer Substrates and Its Impact on Integrated Photonic Structures}, series = {Polymers}, volume = {16}, journal = {Polymers}, number = {2}, doi = {10.3390/polym16020168}, pages = {168 -- 168}, year = {2024}, abstract = {This contribution quantifies the birefringence within injection-molded cyclic olefin copolymer plates and discusses its impact on the mechanical properties of the plates. It also focuses on the impact of birefringence on integrated waveguides and Bragg gratings and provides fabrication guidelines for such structures. The anisotropy in all three dimensions of the workpiece is examined by means of polarimetry and a prism coupler. It is found that the birefringence is inhomogenously distributed within the workpieces, whereas the maximum birefringence not only varies locally, but also depends on the observation direction. Overall, a maximum birefringence of 10 × 10-4 is found at the plate's surface near the injection gate. The anisotropy then reduces exponentially towards the center of the workpiece and saturates at 1.8 × 10-4, in a depth of 0.4 mm. Thus, the birefringence strongly affects near-surface photonic structures. It is found that, depending on their orientation and the local birefringence of the substrate, waveguides and Bragg gratings fabricated with comparable parameters behave completely differently in terms of polarization-dependent optical attenuation, cross-sectional intensity distribution and Bragg reflection signal. For example, the support of the TM mode can vary between total loss and an optical attenuation of 0.9 dB × cm-1. In consequence, this study underlines the importance of quantifying the birefringent state of an injection-molded cyclic olefin copolymer workpiece if it is supposed to serve as a substrate for integrated photonic structures. The study furthermore demonstrates that birefringence effects can be omitted by burying the photonic structures deeper into the volume of the thermoplastic.}, subject = {Bragg-Reflektor}, language = {en} } @article{TrentThielemannMonici2024, author = {Trent, Davis and Thielemann, Christiane and Monici, Monica}, title = {How are cell and tissue structure and function influenced by gravity and what are the gravity perception mechanisms?}, series = {npj Microgravity}, volume = {2014}, journal = {npj Microgravity}, number = {10 / 16}, doi = {10.1038/s41526-024-00357-9}, pages = {1 -- 7}, year = {2024}, abstract = {Progress in mechanobiology allowed us to better understand the important role of mechanical forces in the regulation of biological processes. Space research in the field of life sciences clearly showed that gravity plays a crucial role in biological processes. The space environment offers the unique opportunity to carry out experiments without gravity, helping us not only to understand the effects of gravitational alterations on biological systems but also the mechanisms underlying mechanoperception and cell/tissue response to mechanical and gravitational stresses. Despite the progress made so far, for future space exploration programs it is necessary to increase our knowledge on the mechanotransduction processes as well as on the molecular mechanisms underlying microgravity-induced cell and tissue alterations. This white paper reports the suggestions and recommendations of the SciSpacE Science Community for the elaboration of the section of the European Space Agency roadmap "Biology in Space and Analogue Environments" focusing on "How are cells and tissues influenced by gravity and what are the gravity perception mechanisms?" The knowledge gaps that prevent the Science Community from fully answering this question and the activities proposed to fill them are discussed.}, subject = {Zellkultur}, language = {en} } @article{VoigtMoeckel2022, author = {Voigt, Jorrit and M{\"o}ckel, Michael}, title = {Benchmarking a multi-layer approach and neural network architectures for defect detection in PBF-LB/M}, series = {Materials Today Communications}, volume = {2022}, journal = {Materials Today Communications}, number = {33/104878}, doi = {https://doi.org/10.1016/j.mtcomm.2022.104878}, pages = {* -- *}, year = {2022}, abstract = {The substitution of expensive non-destructive material testing by data-based process monitoring is intensively explored in quality assurance for additive manufactured components. Machine learning show promising results for defect detection but require conceptual adaption to layer wise manufacturing and line scanning patterns in laser powder bed fusion. A multi-layer approach to co-register µ-computer tomography measurements with process monitoring data is developed and a workflow for automatic data set generation is implemented. The objective of this research is to benchmark the volumetric multi-layer approach and specifically selected deep learning methods for defect detection. The volumetric approach shows superior results compared to single slice monitoring. All investigated structured neural network topologies deliver similar performance.}, subject = {Neuronales Netz}, language = {en} } @article{VoigtBockHilpertetal.2022, author = {Voigt, Jorrit and Bock, Thomas and Hilpert, Uwe and Hellmann, Ralf and M{\"o}ckel, Michael}, title = {Increased relative density and characteristic melt pool Signals at the edge in PBF-LB/M}, series = {Additive Manufacturing}, volume = {2022}, journal = {Additive Manufacturing}, number = {57/102798}, doi = {https://doi.org/10.1016/j.addma.2022.102798}, pages = {* -- *}, year = {2022}, abstract = {Limited process control can cause metallurgical defect formation and inhomogeneous relative density in laser powder bed fusion manufactured parts. This study shows that process monitoring, based on optical melt-pool signal analysis is capable of tracing relative density variations: Unsupervised machine learning, applied to cluster multiple-slice monitoring data, reveals characteristic patterns in this noisy time-series signal, which can be co-registered with geometrical positions in the build part. For cylindrical 15-5 PH stainless steel specimens, manufactured under constant process parameters and post-analyzed by µ-computer tomography, correlations between such patterns and an increased local relative density at the edge have been observed. Finite element method (FEM) modeling of thermal histories at exemplary positions close to the edge suggest pre-heating effects caused by neighboring laser scan trajectories as possible reasons for the increased melt pool intensity at the edge.}, subject = {Maschinelles Lernen}, language = {en} } @article{PinedaAlvesMoeckeletal.2023, author = {Pineda, Aruane M. and Alves, Caroline L. and M{\"o}ckel, Michael and de O Toutain, Thaise Graziele L and Moura Porto, Joel Augusto and Rodrigues, Francisco A.}, title = {Analysis of quantile graphs in EGC data from elderly and young individuals using machine learning and deep learning}, series = {Journal of Complex Networks}, volume = {2023}, journal = {Journal of Complex Networks}, number = {11/5}, doi = {https://doi.org/10.1093/comnet/cnad030}, pages = {* -- *}, year = {2023}, abstract = {Heart disease, also known as cardiovascular disease, encompasses a variety of heart conditions that can result in sudden death for many people. Examples include high blood pressure, ischaemia, irregular heartbeats and pericardial effusion. Electrocardiogram (ECG) signal analysis is frequently used to diagnose heart diseases, providing crucial information on how the heart functions. To analyse ECG signals, quantile graphs (QGs) is a method that maps a time series into a network based on the time-series fluctuation proprieties. Here, we demonstrate that the QG methodology can differentiate younger and older patients. Furthermore, we construct networks from the QG method and use machine-learning algorithms to perform the automatic diagnosis, obtaining high accuracy. Indeed, we verify that this method can automatically detect changes in the ECG of elderly and young subjects, with the highest classification performance for the adjacency matrix with a mean area under the receiver operating characteristic curve close to one. The findings reported here confirm the QG method's utility in deciphering intricate, nonlinear signals like those produced by patient ECGs. Furthermore, we find a more significant, more connected and lower distribution of information networks associated with the networks from ECG data of the elderly compared with younger subjects. Finally, this methodology can be applied to other ECG data related to other diseases, such as ischaemia.}, subject = {Maschinelles Lernen}, language = {en} } @article{StierXuGoldetal.2024, author = {Stier, Simon P. and Xu, Xukuan and Gold, Lukas and M{\"o}ckel, Michael}, title = {Ontology-Based Battery Production Dataspace and Its Interweaving with Artificial Intelligence-Empowered Data Analytics}, series = {Energy Technology}, volume = {2024}, journal = {Energy Technology}, number = {2301305}, doi = {https://doi.org/10.1002/ente.202301305}, pages = {1 -- 13}, year = {2024}, abstract = {Heart disease, also known as cardiovascular disease, encompasses a variety of heart conditions that can result in sudden death for many people. Examples include high blood pressure, ischaemia, irregular heartbeats and pericardial effusion. Electrocardiogram (ECG) signal analysis is frequently used to diagnose heart diseases, providing crucial information on how the heart functions. To analyse ECG signals, quantile graphs (QGs) is a method that maps a time series into a network based on the time-series fluctuation proprieties. Here, we demonstrate that the QG methodology can differentiate younger and older patients. Furthermore, we construct networks from the QG method and use machine-learning algorithms to perform the automatic diagnosis, obtaining high accuracy. Indeed, we verify that this method can automatically detect changes in the ECG of elderly and young subjects, with the highest classification performance for the adjacency matrix with a mean area under the receiver operating characteristic curve close to one. The findings reported here confirm the QG method's utility in deciphering intricate, nonlinear signals like those produced by patient ECGs. Furthermore, we find a more significant, more connected and lower distribution of information networks associated with the networks from ECG data of the elderly compared with younger subjects. Finally, this methodology can be applied to other ECG data related to other diseases, such as ischaemia.}, subject = {Batterie}, language = {en} } @article{ZanottoZapataDominguezAyerbeetal.2022, author = {Zanotto, Franco M. and Zapata Dominguez, Diana and Ayerbe, Elixabete and Boyano, Iker and Burmeister, Christine and Duquesnoy, Marc and Eisentraeger, Marlene and Florez Monta{\~n}o, Jonathan and Gallo-Bueno,, Alfonso and Gold, Lukas and Hall, Florian and Kaden, Nicolaj and Muerkens, Bernhard and Otaegui, Laida and Reynier, Yvan and Stier, Simon and Thomitzek, Matthias and Turetskyy, Artem and Vallin, Nicolas and Wessel, Jacob and Xu, Xukuan and Abbasov, Jeyhun and Franco, Alejandro A.}, title = {Data Specifications for Battery Manufacturing Digitalization: Current Status, Challenges, and Opportunities}, series = {Chemistry Europe - Batteries \& Supercaps}, volume = {2022}, journal = {Chemistry Europe - Batteries \& Supercaps}, number = {5/9}, doi = {https://doi.org/10.1002/batt.202200224}, pages = {1 -- 35}, year = {2022}, abstract = {Lithium-ion battery (LIB) manufacturing requires a pilot stage that optimizes its characteristics. However, this process is costly and time-consuming. One way to overcome this is to use a set of computational models that act as a digital twin of the pilot line, exchanging information in real-time that can be compared with measurements to correct parameters. Here we discuss the parameters involved in each step of LIB manufacturing, show available computational modeling approaches, and discuss details about practical implementation in terms of software. Then, we analyze these parameters regarding their criticality for modeling set-up and validation, measurement accuracy, and rapidity. Presenting this in an understandable format allows identifying missing aspects, remaining challenges, and opportunities for the emergence of pilot lines integrating digital twins. Finally, we present the challenges of managing the data produced by these models. As a snapshot of the state-of-the-art, this work is an initial step towards digitalizing battery manufacturing pilot lines, paving the way toward autonomous optimization.}, subject = {Batterie}, language = {en} } @article{AlvesCibadeOToutainetal.2024, author = {Alves, Caroline L. and Ciba, Manuel and de O Toutain, Thaise Graziele L and Moura Porto, Joel Augusto and de Sena, Eduardo Pond{\´e} and Thielemann, Christiane and Rodrigues, Francisco A.}, title = {On the advances in machine learning and complex network measures to an EEG dataset from DMT experiments}, series = {Journal of Physics: Complexity}, volume = {2024}, journal = {Journal of Physics: Complexity}, number = {1}, doi = {10.1088/2632-072X/ad1c68}, pages = {1 -- 2}, year = {2024}, abstract = {There is a growing interest in the medical use of psychedelic substances, as preliminary studies using them for psychiatric disorders have shown positive results. In particular, one of these substances is N, N-dimethyltryptamine (DMT), an agonist serotonergic psychedelic that can induce profound alterations in the state of consciousness. In this work, we use an exploratory tool to reveal DMT-induced changes in brain activity using EEG data and provide new insights into the mechanisms of action of this psychedelic substance. We used a two-class classification based on (A) the connectivity matrix or (B) complex network measures derived from it as input to a support vector machine. We found that both approaches could detect changes in the brain's automatic activity, with case (B) showing the highest AUC (89\%), indicating that complex network measurements best capture the brain changes that occur due to DMT use. In the second step, we ranked the features that contributed the most to this result. For case (A), we found that differences in the high alpha, low beta, and delta frequency bands were most important in distinguishing between the state before and after DMT inhalation, which is consistent with the results described in the literature. Further, the connection between the temporal (TP8) and central cortex (C3) and between the precentral gyrus (FC5) and the lateral occipital cortex (P8) contributed most to the classification result. The connection between regions TP8 and C3 has been found in the literature associated with finger movements that might have occurred during DMT consumption. However, the connection between cortical areas FC5 and P8 has not been found in the literature and is presumably related to the volunteers' emotional, visual, sensory, perceptual, and mystical experiences during DMT consumption. For case (B), closeness centrality was the most crucial complex network measure. Furthermore, we discovered larger communities and longer average path lengths when DMT was used and the converse when not, showing that the balance between functional segregation and integration had been disrupted. These findings support the idea that cortical brain activity becomes more entropic under psychedelics. Overall, a robust computational workflow has been developed here with interpretability of how DMT (or other psychedelics) modify brain networks and insights into their mechanism of action. Finally, the same methodology applied here may help interpret EEG time series from patients who consumed other psychedelic drugs.}, subject = {Neuronales Netz}, language = {en} } @article{MoniciThielemann2023, author = {Monici, Monica and Thielemann, Christiane}, title = {How do gravity alterations affect animal and human systems at a cellular/tissue level?}, series = {nature npj Microgravity}, volume = {2023}, journal = {nature npj Microgravity}, number = {9/84}, doi = {https://doi.org/10.1038/s41526-023-00330-y}, pages = {1 -- 9}, year = {2023}, abstract = {The present white paper concerns the indications and recommendations of the SciSpacE Science Community to make progress in filling the gaps of knowledge that prevent us from answering the question: "How Do Gravity Alterations Affect Animal and Human Systems at a Cellular/Tissue Level?" This is one of the five major scientific issues of the ESA roadmap "Biology in Space and Analogue Environments". Despite the many studies conducted so far on spaceflight adaptation mechanisms and related pathophysiological alterations observed in astronauts, we are not yet able to elaborate a synthetic integrated model of the many changes occurring at different system and functional levels. Consequently, it is difficult to develop credible models for predicting long-term consequences of human adaptation to the space environment, as well as to implement medical support plans for long-term missions and a strategy for preventing the possible health risks due to prolonged exposure to spaceflight beyond the low Earth orbit (LEO). The research activities suggested by the scientific community have the aim to overcome these problems by striving to connect biological and physiological aspects in a more holistic view of space adaptation effects.}, subject = {Raumfahrt}, language = {en} } @article{PolyakovWeidl1997, author = {Polyakov, Maxim V. and Weidl, Galia}, title = {Chiral expansion in the dual (string) model of the Goldstone meson scattering}, series = {High Energy Physics - Phenomenology}, volume = {1997}, journal = {High Energy Physics - Phenomenology}, number = {0/0}, doi = {10.48550/arXiv.hep-ph/9612486}, pages = {1 -- 13}, year = {1997}, abstract = {We consider in details the dual models for the Goldstone mesons (pions) scattering in the presence of the explicit chiral symmetry breaking caused by non-zero current quark mass. New method of incorporation of the quark masses into the dual model is suggested. In contrast to the previously considered in the literature methods, the dual amplitude obtained by this method is consistent with all low-energy theorems following from the Effective Chiral Lagrangian (EChL) to the O(p^4) order and simultaneously it does not contain states with negative width. The resonance spectrum of the model and its implications for the fourth and sixth order EChL in large N_c limit are discussed. We argue that the possible relations between large N_c QCD and some underlying string theory can be revealed by studying interactions of hadrons at low-energies.}, subject = {Stringtheorie}, language = {en} } @article{WeidlMadsenDahlquist2002, author = {Weidl, Galia and Madsen, Anders L. and Dahlquist, Erik}, title = {Condition Monitoring, Root Cause Analysis and Decision Support on Urgency of Actions}, series = {Book Series FAIA (Frontiers in Artificial Intelligence and Applications), Soft Computing Systems - Design, Management and Applications}, volume = {2002}, journal = {Book Series FAIA (Frontiers in Artificial Intelligence and Applications), Soft Computing Systems - Design, Management and Applications}, number = {87}, pages = {221 -- 230}, year = {2002}, abstract = {We discuss the use of a hybrid system utilizing Object Oriented Bayesian networks and influence diagrams for probabilistic reasoning under uncertainties in industrial process operations. The Bayesian networks are used for condition monitoring and root cause analysis of process operation. The recommended decision sequence of corrective actions and observations is obtained following the "myopic" approach. The BN inference on most probable root cause is used in an influence diagram for taking decisions on urgency of corrective actions vs. delivery deadline. The build-in chain of causality from root cause to process faults can provide the user with explanation facility and a simulation tool of the effect of intended actions.}, subject = {Prozesssteuerung}, language = {en} }