Gutenberg Open Science (Univ. Mainz)
Not a member yet
11784 research outputs found
Sort by
Effects of chiral polypeptides on skyrmion stability and dynamics
No full textMagnetic skyrmions, topologically stabilized chiral spin textures in magnetic thin films, have garnered considerable interest due to their efficient manipulation and resulting potential as efficient nanoscale information carriers. One intriguing approach to address the challenge of tuning skyrmion properties involves using chiral molecules. Chiral molecules can locally manipulate magnetic properties by inducing magnetization through spin exchange interactions and by creating spin currents. Here, Magneto-Optical Kerr Effect (MOKE) microscopy is used to image the impact of chiral polypeptides on chiral magnetic structures. The chiral polypeptides shift the spin reorientation transition temperature, reduce thermal skyrmion motion, and alter the coercive field locally, enhancing skyrmion stability and thus enabling local control. These findings demonstrate the potential of chiral molecules to address challenges for skyrmion based devices, thus paving the way to applications such as the racetrack memory, reservoir computing and others
Raw data for "Mechanistic insights: correspondence on “Tuning co-operative energy transfer in copper(I) complexes using two-photon absorbing diimine-based ligand sensitizers”"
No full textIn a recent communication, Collins and co-workers presented a Cu(I) complex with photocatalytic activity under red light LED conditions, mainly for singlet oxygen-driven reactions. Guided by steady-state emission measurements with 800 nm excitation, the authors suggested that the underlying mechanism for the generation of the photoexcited key species is a simultaneous two-photon absorption via a virtual state. However, such a mechanism requires pulsed laser excitation and cannot compete when a conventional one-photon excitation is also feasible with the selected excitation wavelength range. Using several spectroscopic techniques and reactivity assays under different light color and intensity conditions, we unambiguously demonstrate that a conventional one-photon excitation followed by rather inefficient singlet oxygen generation (quantum yield < 5%) is responsible for the observed photoreactivity of the Cu(I) complex. In addition, we briefly summarize general mechanistic considerations, estimate typical photon densities required for a variety of two-photon mechanisms, highlight the importance of optical filters and impurities to avoid artifacts in the emission spectra, and present some guidelines for the differentiation between one- and two-photon mechanisms.Experiment
Repeated fractionation and umbel receptacle elongation explain the apparent “panicle with simple umbels” in Ferula species (Apiaceae)
Get PDFIntroduction: The carrot family (Apiaceae) is characterized by umbels with umbellets. Traditionally, these umbels are interpreted as inflorescences. Ontogenetic studies, however, indicate that they do not originate from inflorescence meristems but from flower-like floral unit meristems. These meristems repeatedly fractionate sub-meristems, which give rise to umbellets and flowers. Ferula species usually form double racemes with umbels with umbellets. Few species of the genus, previously grouped in the genus Dorema, however, present “panicles with simple umbels”.
Methods: Aiming to identify the developmental processes resulting in the different inflorescence appearance, we investigate inflorescence development in Ferula hezarlalehzarica (double racemes with umbels with umbellets) and Ferula aucheri (panicles with simple umbels).
Results: Both species are andromonoecious (perfect and staminate flowers) and produce huge yellow inflorescences. SEM studies confirm that they share the same developmental patterns. Their development starts with an inflorescence meristem segregating umbel meristems. These pass through two steps of fractionation generating first umbellet meristems and then flower meristems. F. aucheri differs from F. hezarlalehzarica by i) producing several lateral inflorescences apart from one terminal one and ii) extremely elongating the umbel receptacles, thereby separating the umbellets from each other. The unusual branches with simple umbels thus prove to be homologous to umbels with umbellets. Furthermore, F. aucheri shows some intermediate inflorescences with umbellets intermixed with umbels. Considering that umbels and umbellets only differ in one step of fractionation, we interpret this mixture as developmental lability.
Discussion: The study shows that meristem conditions define the character of the umbels as floral units and that developmental processes like fractionation, expansion, and elongation shape their outer appearance. It illustrates that inflorescences can be easily misinterpreted if only adult branching systems are investigated
Visual political communication on Instagram : a comparative study of Brazilian presidential elections
Get PDFIn today’s digital age, images have become powerful tools for politicians to engage with their voters on social media platforms. Visual content possesses a unique emotional appeal that often leads to increased user engagement. However, research on visual communication remains relatively limited, particularly in the Global South. This study aims to bridge this gap by employing a combination of computational methods and qualitative approach to investigate the visual communication strategies employed in a dataset of 11,263 Instagram posts by 19 Brazilian presidential candidates in 2018 and 2022 national elections. Through two studies, we observed consistent patterns across these candidates on their use of visual political communication. Notably, we identify a prevalence of celebratory and positively toned images. They also exhibit a strong sense of personalization, portraying candidates connected with their voters on a more emotional level. Our research also uncovers unique contextual nuances specific to the Brazilian political landscape. We note a substantial presence of screenshots from news websites and other social media platforms. Furthermore, text-edited images with portrayals emerge as a prominent feature. In light of these results, we engage in a discussion regarding the implications for the broader field of visual political communication. This article contributes by showing the ways Instagram was used in the digital political strategy of two fiercely polarized Brazilian elections, shedding light on the ever-evolving dynamics of visual political communication in the digital age. Finally, we propose avenues for future research in the field of political communication
Analyse der gesundheitsbezogenen postoperativen Lebensqualität nach Operation einer Hiatushernie mittels Hiatoplastik und Fundoplicatio
Get PDF105 Seiten ; Illustrationen, Diagramm
Realizing quantitative quasiparticle modeling of skyrmion dynamics in arbitrary potentials
Get PDFWe demonstrate fully quantitative Thiele model simulations of magnetic skyrmion dynamics on previously unattainable experimentally relevant large length and time scales by ascertaining the key missing parameters needed to calibrate the experimental and simulation timescales and current-induced forces. Our work allows us to determine complete spatial pinning energy landscapes that enable quantification of experimental studies of diffusion in arbitrary potentials within the Lifson-Jackson framework. Our method enables us to ascertain the timescales, and by isolating the effect of ultralow current density (order 10^{6} A/m^{2}) generated torques we directly infer the total force acting on the skyrmion for a quantitative modeling
Elucidating the role of the transcription factor interferon regulatory factor 4 in differentiated T helper 17 and regulatory T cells
No full textV, 137 Seiten ; Illustrationen, Diagramm
Einfluss einer vorherigen Statin-Therapie auf das klinische Outcome nach zerebralem Großgefäßverschluss und mechanischer Thrombektomie
No full text88, XIX Seiten ; Illustrationen, Diagramm
Exploring transcriptomic regulation of the developing brain through integrative bioinformatics and deep learning approaches
Get PDFThe mammalian brain is a remarkably complex organ whose development relies on precise molecular and cellular processes. One of the most sophisticated brain structures is the cerebral cortex. Many proteins and microRNAs play distinct roles in the posttranscriptional regulation of corticogenesis. Mutations in RNA-binding proteins and miRNAs are linked to neurodevelopmental disorders, highlighting their crucial role in central nervous system development.
This doctoral thesis investigates posttranscriptional mechanisms that shape brain development, focusing on alternative splicing and microRNA regulation. Premature overexpression of the RNA binding protein Rbfox2 during murine corticogenesis caused migration and differentiation defects through an altered splicing pattern, likely antagonizing PTBP2’s splicing program. In this study, it was further shown that the neuronal progenitor cell-specific miR-92a-3p repressed Rbfox2 both in vitro and in vivo, revealing a novel regulatory relationship between miRNAs and splicing factors during neural development.
Furthermore, analysis of miRNAs during embryonic corticogenesis revealed clusters of coregulated miRNAs with overlapping target sets. Luciferase assays showed that such cotargeting of miRNAs enhances the repression effect on shared target mRNAs. This finding suggests a complex regulatory network where multiple miRNAs cooperatively fine-tune gene expression during brain development.
To support future research, two computational tools were developed: a web portal (www.cortexa-rna.com) providing access to neocortex/hippocampus RNA-sequencing datasets, improving the accessibility of transcriptomic data to the broader scientific community. Additionally, I implemented a deep learning framework for denoising functional imaging recordings. This computational tool enables the validation of molecular changes in synaptic function at single synapse resolution, bridging the gap between molecular alterations (including splicing-induced changes) and their functional consequences in neurons.182 Seiten ; Illustrationen, Diagramm