11723 research outputs found
Sort by
Detection and Visual Analysis of 3-D Atmospheric Fronts – from Individual Cases to Ensembles
Get PDFAtmospheric fronts are a widely used conceptual model in meteorology, most encountered as two-dimensional (2-D) front lines on surface analysis charts. The three-dimensional (3-D) dynamical structure of fronts has been studied in the literature by means of “standard” 2-D maps and cross-sections and is commonly sketched in 3-D illustrations of idealised weather systems in atmospheric science textbooks. However, only recently has the feasibility of the objective detection and visual analysis of 3-D frontal structures and their dynamics within numerical weather prediction (NWP) data been proposed, and such approaches are not yet widely known in the atmospheric science community. In this thesis, I investigate the benefit of objective 3-D front detection for case studies of extra-tropical cyclones and for comparison of frontal structures between different NWP models. I build on a recent gradient-based detection approach, combined with modern 3-D interactive visual analysis techniques, and adapt it to handle data from state-of-the-art NWP models including those run at convection-permitting kilometre-scale resolution. The parameters of the detection method (including data smoothing and threshold parameters) are evaluated to yield physically meaningful structures. I illustrate the benefit of the method by presenting two case studies of frontal dynamics within mid-latitude cyclones. Examples include joint interactive visual analysis of 3-D fronts and Warm Conveyor Belt (WCB) trajectories, as well as identification of the 3-D frontal structures characterising the different stages of a Shapiro–Keyser cyclogenesis event. The 3-D frontal structures show agreement with 2-D fronts from surface analysis charts and augment the surface charts by providing additional pertinent information in the vertical dimension. A second application illustrates the relation between convection and 3-D cold-front structure by comparing data from simulations with parametrised and explicit convection. Investigation into “secondary fronts” that are commonly shown in UK Met Office surface analysis charts shows that for this event the secondary front is not a temperature-dominated but a humidity-dominated feature.
Building on this 3-D front detection approach, I extend the detection of individual 3-D fronts towards front-feature-based time series analysis and ensemble clustering. Ensemble simulations have become a standard in NWP. However, ensemble simulations generate large amounts of data and their analysis remains a challenge. In this thesis, I develop a manual and automated front-tracking algorithm based on geometric and physical characteristics to derive time series of frontal attributes from a selected cyclone system. These frontal attributes characterise the 3-D front by one-dimensional (1-D) physical properties, such as the average slope of the 3-D frontal structure. By tracking a selected front over successive time steps, time series of frontal attributes are derived to provide a compact view of the development of frontal attributes. To order and cluster ensemble simulations according to frontal attributes, a selected front automatically tracked across all ensemble members and front attribute time series are derived for each member. These feature time series are then ordered and clustered using time series distance measures in combination with k-means clustering, resulting in distinct clusters that represent different patterns of frontal evolution across ensemble members.
Integrated into the 3-D interactive visual analysis framework Met.3D, my approach allows a comprehensive analysis of the spatio-temporal evolution of 3-D atmospheric fronts and thus contributes to the challenge of rapid analysis of large ensemble weather forecasts, as well as having great potential for operational weather forecasting
Heritage Bilingualism and the Acquisition of English as an Additional Language (L3) in the German Context: A Longitudinal Study
Get PDFThis dissertation investigated the links between heritage bilingualism and the longitudinal development of L3 English in the German secondary education context by employing a longitudinal design. In addition to examining L3 English longitudinal growth trajectories and growth rate in heritage bilingual students, the dissertation research examined which linguistic (i.e., heritage language proficiency, majority language proficiency, and L1 background) and extra-linguistic (i.e., cognitive ability, socioeconomic status, and school type) factors exerted an impact on L3 English development. The participants were 301 heritage bilingual students (Russian-German=123, Turkish-German=178) sampled from 72 schools across eight federal states in Germany. The students participated in the first three waves of the MEZ project (MEZ—2014–2019), which examined the multilingual development of secondary school students in the German educational context. The longitudinal data initially were examined by using a set of descriptive and inferential statistics (e.g., analysis of difference and correlational analysis). The main analyses were conducted by using the Latent Growth Curve Modelling methodology in the context of Structural Equation Modelling. The latent growth curve modelling results showed that the baseline, the initial level of L3 English, was significantly positive. Additionally, a slight yet statistically significant variation was detected at the baseline in L3 English scores. The mean of the linear slope, the rate of growth, was found to be slightly negative, with scores decreasing by 0.061, on average, across three measurement time points. Moreover, the results demonstrated that heritage bilingual students did not vary considerably in terms of their L3 English growth trajectories over time. Furthermore, it was found that heritage bilingual students’ initial L3 English scores did not necessarily predict their L3 English growth across three measurement time points. Concerning the links between linguistic and extra-linguistic variables and L3 English growth, the analyses revealed that, notably the effect of the majority language proficiency, German, was significant and positive across all three MTPs for the baseline. The effect of heritage language proficiency was significant and positive at MTP1, negative and not significant at MTP2, and negative and significant at MTP3. The impact of school type was statistically significant, meaning that attending the Gymnasium was strongly associated with a higher L3 English proficiency initial level. The effect of socioeconomic background was negative but statistically not significant while the effect of cognitive ability was positive and statistically significant. When it comes to L3 English growth, the results indicated that both heritage language proficiency and the majority language proficiency did not seem to predict linear growth over time. The impact of German proficiency on growth was positive at MPT2 and MPT3, while the impact of heritage language proficiency was negative across all MPTs, yet the associated p values did not reach statistical significance. School type remained a marginally significant predictor for L3 English growth. Socioeconomic background contributed positively to L3 English longitudinal growth whereas cognitive ability was not found to impact the growth. Language background was a statistically significant predictor for L3 English growth, particularly indicating an advantage for the Russian-German group compared to the Turkish-German group. Overall, the results did not indicate a clear bilingual advantage due to a lack of a positive pattern in L3 growth trajectories and growth rate. The lack of linear growth may stem from the influence of extra-linguistic, i.e., contextual factors, participants’ age, educational level, and bilingual profiles, and the status of heritage languages in educational, societal, and home settings
Das Zusammenspiel aus motorischen Kompetenzen, deren Selbstwahrnehmung und gesundheitsbezogenen Faktoren in der Kindheit
Get PDFIn dieser kumulativen Dissertation wird das komplexe Zusammenspiel zwischen tatsächlicher und wahrgenommener motorischer Kompetenz, körperlicher Aktivität und Parametern der mentalen Gesundheit im frühen Kindesalter (4 bis 8 Jahre) untersucht. Dabei bewegen sich die Untersuchungen im Feld zwischen Bildungswissenschaft, Motorikforschung und Gesundheitswissenschaften. In vier empirischen Studien wird ein ganzheitlicher, kindzentrierter Blick auf Faktoren der motorischen Entwicklung gelegt, wobei motorische Kompetenzen nicht nur als physische Kompetenzen, sondern als Teil eines motivationalen und psychosozialen Systems verstanden werden. Die Dissertation basiert auf den Modellen von Stodden et al. (2008) sowie der erweiterten Fassung von Lima et al. (2022). Als Ausganspunkt der EMOKK-Studie (Entwicklung motorischer Basiskompetenzen in der Kindheit), in die diese Dissertation eingebettet war, wird das Angebots-Nutzungs-Modell von Helmke (2014) herangezogen und um gesundheitsbezogene Faktoren erweitert, um neben körperlicher Aktivität die soziale Integration und gesundheitsbezogene Lebensqualität als Faktoren der mentalen Gesundheit zu untersuchen.
Im Rahmen der ersten Publikation wurde das SEMOK-1-2 Instrument entwickelt und validiert – welches die wahrgenommene motorische Kompetenz von Kindern der ersten und zweiten Klasse (6-8 Jahre) erfasst. Das SEMOK-1-2 wurde analog zum MOBAK-1-2 Instrument (Herrmann, 2018) entwickelt. Die 404 Kinder, welche an der Studie teilnahmen, konnten die Aufgaben, die von einem Fuchs vorgemacht wurden, auf einer dreistufigen Antwortskala, analog zum MOBAK Instrument, beantworten. Die zweifaktorielle Struktur der MOBAK-Instrumente konnte bestätigt werden. Zudem zeigten sich hohe latente Zusammenhänge zwischen tatsächlicher Kompetenz und deren Selbstwahrnehmung im Etwas-Bewegen und Sich-Bewegen. Jungen und Kinder, die häufiger am Teamsport teilnahmen, zeigten höhere tatsächliche Kompetenzen und eine höhere Selbstwahrnehmung im Etwas-Bewegen.
In der zweiten Publikation wurde das Zusammenspiel zwischen motorischen Kompetenzen und sozialen Beziehungen von 548 Kindergartenkindern (4-6 Jahre) untersucht. Mittels Strukturgleichungsmodellen zeigten sich positive latente Zusammenhänge zwischen den motorischen Kompetenzen und der sozialen Integration in die Klasse, wobei Kinder mit höheren motorischen Kompetenzen besser integriert zu sein schienen. Dabei fielen die Zusammenhänge zwischen den Konstrukten bei den Jungen deutlich stärker aus als bei den Mädchen.
In der dritten Publikation konnten die Zusammenhänge zwischen sozialer Integration und motorischen Kompetenzen, sowohl für Kinder des Kindergartens (n = 1163) als auch der ersten und zweiten Klasse (n = 880) bestätigt werden. Zudem wurde das Konstrukt der gesundheitsbezogenen Lebensqualität (HRQoL) als bedeutsames Konstrukt der mentalen Gesundheit eingeführt und die Zusammenhänge mit sozialer Integration und motorischen Kompetenzen untersucht. Im Kindergarten zeigten sich weder Zusammenhänge zwischen der generellen HRQoL und den motorischen Kompetenzen noch mit der sozialen Integration. Bei Kindern der ersten und zweiten Klasse konnten geringe Zusammenhänge zwischen der generellen HRQoL mit der sozialen Integration der Kinder, als auch mit der Kompetenz im Sich-Bewegen festgestellt werden. Bei der Untersuchung des körperlichen Wohlbefindens bei Kindergartenkindern konnte ein moderater Zusammenhang mit den motorischen Kompetenzen festgestellt werden, wobei dieser für das Sich-Bewegen höher ausfiel.
In der vierten Publikation wurden mittels latenter Profilanalysen drei Gruppen von Kindern identifiziert, welche sich hinsichtlich der Faktoren Sportengagement, motorische Kompetenzen, deren Selbstwahrnehmung und Wohlbefinden unterschieden. Dabei konnte ein Profil als „Risikoprofil“ identifiziert werden, wobei die Kinder ein geringes Sportengagement, geringe motorische Kompetenzen sowie geringe Werte im Wohlbefinden aufwiesen.
Zusammenfassend kann festgehalten werden, dass motorische Kompetenzfaktoren mit Parametern der mentalen Gesundheit in Zusammenhang stehen und somit das Modell von Lima et al., (2022) unterstützt. Zudem trägt diese Dissertation zu einer ganzheitlichen, interdisziplinären Betrachtung von motorischen Kompetenzfaktoren im Kindesalter bei. Sie hebt die Wechselwirkungen zwischen Motorik, Selbstwahrnehmung, Sportpartizipation und psychosozialer Gesundheit hervor. Auf Basis von Querschnittsdaten bietet sie wichtige Einblicke in das Zusammenspiel dieser Faktoren, bildet die Basis für Langzeitstudien und unterstreicht gleichzeitig die Notwendigkeit dieser. Durch die Verbindung von verschiedenen Wissenschaftsdisziplinen liefert die Arbeit theoretische und praktische Grundlagen für weitere Forschung sowie inklusivere Interventionen im schulischen und außerschulischen Kontext.This cumulative dissertation examines the complex interplay between actual motor competencies (AMC), perceived motor competencies (PMC), physical activity (PA), and mental health parameters in early childhood (at 4–8 years). Situated at the intersection of educational science, motor development research, and health science, the studies aim to address theoretical and empirical gaps. In four empirical studies, a holistic, child-centered perspective is adopted viewing AMC not only as physical competencies but also as a part of a motivational and psychosocial system. This dissertation is primarily based on models by Stodden et al. (2008) and the version expanded by Lima et al. (2022). The EMOKK project (in English: Development of Basic Motor Competencies in Childhood), in which the present dissertation is embedded, used Helmke’s (2014) offer-and-use model as its theoretical foundation. Helmke’s model was expanded to include health-related factors to examine PA and mental health parameters, such as social integration and health-related quality of life (HRQoL).
In the first publication, the SEMOK-1-2 instrument—an instrument for assessing the PMC of first- and second-grade children (ages 6–8 years)—was developed and validated. The SEMOK-1-2 instrument conceptually closely aligns with a measure of AMC, namely the MOBAK-1-2 instrument (Herrmann, 2018). The included 404 children responded to tasks, demonstrated by an illustrated fox, using a 3-point scale analogous to the MOBAK-1-2 instrument. The two-factor structure of the MOBAK instrument was confirmed. Additionally, strong latent correlations were found between actual competence and self-perception in both object movement and self-movement. Boys and children who participated more frequently in team sports exhibited higher AMC and PMC in object movement.
The second publication investigated the interplay between AMC and social relationships among 548 preschool children (ages 4–6 years). Structural equation models revealed positive latent correlations between AMC and social integration within the class, with children possessing higher AMC appearing to be better integrated. The associations between the constructs were notably stronger for boys than for girls.
In the third publication, the associations between social integration and AMC were confirmed for both preschool children (n = 1163) and first and second graders (n = 880). Furthermore, the construct of health-related quality of life (HRQoL) was introduced as a key parameter of mental health, and its associations with social integration and AMC were examined. While general HRQoL was unrelated to AMC and social integration in preschool, it was weakly associated with social integration and AMC self-movement in first- and second-grade children. In preschool, a moderate association was found between physical well-being and AMC, with a stronger correlation for self-movement.
In the fourth publication, latent profile analysis identified three groups of children differing in terms of (their) sports engagement, AMC, PMC, and well-being. One profile of children was identified to be “at risk” by showing low levels of PA participation, AMC, and well-being.
In summary, motor competence factors are associated with parameters of mental health, thus supporting the model of Lima et al. (2022). In addition, this dissertation contributes to a holistic, interdisciplinary consideration of motor competence factors in childhood, highlighting the interactions between AMC, PMC, sports participation, and psychosocial health. Based on cross-sectional data, it provides fundamental insights into the interplay of these factors, laying the ground for longitudinal studies. By bridging various scientific disciplines, this work offers theoretical and practical foundations for further research as well as more inclusive interventions in both school and out-of-school contexts
Untersuchungen zum Immuncheckpoint-Molekül VISTA in Urothelkarzinom-Zelllinien und zu zirkulierenden Tumorzellen im Blut von Patient:innen mit Urothelkarzinom der Harnblase
Get PDFTrotz fortschreitender Entwicklungen, insbesondere durch den Einsatz von ICP, stellt das UCB weiterhin eine der häufigsten Krebserkrankungen mit signifikanter Mortalität dar. Dies unterstreicht die Notwendigkeit weiterer Fortschritte auf diagnostischer wie therapeutischer Ebene.
Aktuell basiert die Therapie auf etablierten ICP-Inhibitoren. Eine zusätzliche Blockade weiterer ICP-Moleküle, wie z. B. VISTA, könnte jedoch einen therapeuti-schen Zugewinn darstellen. Die gezielte Inhibition von VISTA wird derzeitig in klinischen Studien untersucht. Allerdings bestehen noch zahlreiche offene Fragen hinsichtlich der Regulation der Expression, der funktionellen Bedeutung sowie des prognostischen Wertes von VISTA bei malignen Erkrankungen.
Im Rahmen dieser Arbeit konnte die Expression von VISTA/VSIR in verschiedenen UCB-Zelllinien nachgewiesen werden. Eine Behandlung mit IFN-γ bzw. TGFβ führte in den Zelllinien zu keiner relevanten Veränderung der Expression. Mehrere Studien deuten darauf hin, dass VISTA-positive Immunzellen potenziell als Biomarker geeignet sein könnten.
Neben Immunzellmarkern rücken auch CTCs zunehmend in den Fokus der Forschung. Die größte Herausforderung bleibt dabei die zuverlässige Detektion, bedingt durch die geringe CTC-Frequenz im peripheren Blut und dem Fehlen eines universellen Oberflächenmarkers. Bis heute existiert kein allgemein anerkanntes Verfahren zur CTC-Isolation. In der vorliegenden Arbeit wurden bei 76 UCB-Patient:innen CTCs mit Hilfe von CellSearch®, Parsortix® und Ficoll-Dichtegradientenzentrifugation angereichert. Auffällige Zellen nach IF wurden zusätzlich mittels WGA und NGS weiter analysiert. Mit allen 3 Methoden konnten CTCs erfolgreich angereichert werden. Die Ergebnisse zeigen, dass die Methoden unterschiedliche CTC-Subpopulationen erfassen: Während CellSearch® primär epitheliale CTCs mit EpCAM-Expression detektiert, ermöglichen die zwei andere Verfahren auch die Anreicherung größerer, weniger plastischer Zellen mit möglichem mesenchymalem Phänotyp. Diese Beobachtungen unterstützendie Notwendigkeit des kombinierten Einsatzes mehrerer Anreicherungsmethoden. Des Weiteren konnte gezeigt werden, dass mit Parsortix® auch CD41-positive Zellen – vermutlich Megakaryozyten – koangereichert werden. Daher sollte CD41 in künftigen Studien als negativer Marker bei der IF-basierten Analyse berücksichtigt werden
Functional 3D printed reactor for continuous oxidation of alcohols to aldehydes
Get PDFThe dissertation focuses on the development of functional 3D-printed reactors for the continuous oxidation of alcohols to aldehydes. Central to the work is a PVC-based reactor with immobilized TEMPO catalysts, offering a more environmentally benign alternative to conventional oxidation methods. Through optimized surface functionalization and improved anchoring of the catalyst, high conversions and enhanced catalyst stability were achieved. The resulting 3D-printed reactors operate efficiently under mild conditions, reaching conversions of up to 100% with long-term stability
Role of Dienelactone Hydrolases (DLHs) in PET Biodegradation and Biofilm Formation by Maribacter dokdonensis and Arenibacter palladensis
Get PDFGlobal plastics pollution represents a major environmental challenge, and we have only a very limited knowledge of marine microorganisms involved in possible remediation. Marine Bacteroidota, particularly members of Flavobacteria, are known for their ability to hydrolyze a wide range of different algal polymers. More recently, some representatives have been identified to encode PET-active enzymes.
PET degradation is primarily conducted by non-specific and secreted enzymes of esterase class (EC 3.1.1-.). They are either designated as carboxylesterases (EC 3.1.1.1), poly(ethylene terephthalate) hydrolases (EC 3.1.1.101), lipases (EC 3.1.1.3) or cutinases (EC 3.1.1.74). Notably, among the currently known and functional PETases no dienelactone hydolases DLHs (3.1.1.45) are listed.
Dienelactone hydrolases are enzymes that play a central role in the degradation of cyclic esters. In the current study, we show that bacteria affiliated with the Bacteroidota (class Flavobacteria) harbor DLHs acting on PET foil and powder. We report on the isolation of two marine bacterial strains, Arenibacter palladensis UHH-Hm9b and Maribacter dokdonensis UHH-5R5, forming biofilms on PET foil and releasing µM amounts of terephthalic acid after 5-7 days. Genome sequencing and functional analyses enables the identification of two secreted DLHs, designated PET93 and PET94, involved in PET degradation. While their predicted active sites and substrates binding pockets were identical to previously published PETases, both enzymes differed largely in their structural features from known PETases and represented novel scaffolds. Moreover, they lacked the typical porC-domain that is characteristic of known PETases from Flavobacteria.
For the two recombinant enzymes PET93 and PET94, activity on PET as well as the primary degradation products Bis(2-Hydroxyethyl) terephthalate (BHET) and Mono- (Hydroxyethyl) terephthalate (MHET) was demonstrated. Both enzymes were able to hydrolyze PET foil and powder at low but significant rates. These findings represent the first described DLHs with activity on plastics. This demonstrates that Flavobacteria harbor a greater diversity of PET-active, albeit unspecific, enzymes than previously assumed.
In addition, the PET94 gene is positioned downstream of Fur-like Transcritiponal regulator, providing a rationale for testing iron supplementation in this experiment. Indeed, this study demonstrated that BHET degradation was enhanced upon iron supplementation, with up to 9-fold increases in MHET concentration detected by UHPLC. However, transcriptome analysis revealed no expression of PET94 under tested conditions, suggesting iron may modulate PET degradation at the post-transcriptional level, or that the applied concentrations were insufficient to trigger transcriptional activation.
In summary, this study highlights the importance of expanding the currently known biodiversity of PET-hydrolyzing enzymes within marine Bacteroidota phylum. PET93, PET94, and their homologs within this phylum are found in diverse climatic zones worldwide, indicating a potentially important role in the degradation of plastic particles in marine ecosystems
Towards Sustainable Food Security in Namibia: Agricultural Adaptation under Future Climate and Development Pathways
Get PDFNamibia faces considerable food insecurity challenges exacerbated by an arid climate, low soil fertility, and socio-economic vulnerabilities, with approximately 58% of the population affected. Smallholder agriculture dominates but is characterized by low productivity and reliance on rainfed systems, making the country heavily dependent on food imports. This dissertation investigates the potential of cowpea—a climate-resilient and nutritionally rich legume—to enhance food security, support rural livelihoods, and improve child nutrition through Namibia’s school feeding programs under current and future climate and socioeconomic scenarios. The research is structured into three integrated studies. The first study assesses cowpea production potentials using biophysical crop simulations combined with spatial optimization, focusing on the effects of rhizobial inoculation, irrigation, and fertilization on yields and resource use efficiency. Results demonstrate that inoculated cowpea yields nearly double those of uninoculated crops in northern Namibia, while irrigation further boosts productivity. Improved practices reduce land and water use intensity, highlighting opportunities for sustainable intensification despite scarce water resources. The study also reveals critical trade-offs between water and land usage that influence optimal production strategies in semi-arid conditions. The second study evaluates whether Namibia’s domestic agriculture can sustainably meet the caloric and nutrient demands of the Home-Grown School Feeding Programme (HGSFP). Simulations show that northern regions can fulfill these demands with potential surpluses under improved management, whereas southern regions remain constrained by harsh biophysical conditions. Protein supply meets requirements nationally, especially with fertilization, although fat remains a limiting nutrient. These findings underscore the potential of domestic agriculture as a reliable supplier for the Namibia HGSFP. It highlights importance of improved farming managements and policy support to mitigate climate change impacts and regional disparities. The third study examines the nutritional and socioeconomic impact of integrating inoculated cowpea flour into the maize-based porridge served in schools. Cowpea fortification significantly enhances protein quality and micronutrient density while maintaining cultural acceptance. Linking local cowpea production with institutional demand strengthens smallholder markets, improves farmer incomes, and facilitates sustainable rural development. Together, these studies establish cowpea production, supported by inoculation and integrated water-nutrient management, as a promising strategy for nutritious and sustainable agriculture in Namibia. The research highlights the HGSFP’s potential as a platform for improving child nutrition, enhancing food system resilience, and reducing import dependence. While offering robust technical insights, this thesis recognizes the need for further research on social and institutional factors to translate findings into effective policy and practice. Ultimately, it contributes key evidence to foster adaptive capacity, food security, and sustainable livelihoods in resource-constrained, semi-arid environments
Deep–Frequency Modulation Interferometry for Gravitational Wave Detectors
No full textThis thesis presents my research on a new type of local displacement sensors proposed to be used in gravitational wave detectors to improve upon the alignment and control noise in the low frequency regime around 3 Hz.
Gravitational wave astronomy is an emerging field using large interferometers with km long arms to measure small displacements of less than 10−20 m/√Hz caused by passing gravitational waves. The currently running LIGO and Virgo detectors are limited in the low-frequency region (below 30 Hz) by alignment and control noises of their suspended optics. As a possible path to improve upon these noise limitations, the use of more precise local sensors to measure the local displacement of the optics, counteract their motion and improve upon their alignment has been proposed. This thesis presents my research on local displacement sensors based on “deep–frequency modulation interferometry (DFMI)” which allows for precise measurements down to displacements in the order of∼100fm/√Hz while simultaneously providing an absolute displacement readout allowing for measurements over a large dynamic range over millimeter and centimeter, necessary for some of the suspended optics in gravitational wave detectors. I present an “analytic readout algorithm” developed to extract the displacement parameters of interest from a measured DFMI signal and I conduct a thorough analysis of the achievable precision limits of DFMI using the “Cram´er-Rao bound”. The readout algorithm I present allows for a faster readout than previous experiments using DFMI, significantly increasing the control bandwidth and the number of sensor channels that can be processed. My noise analysis proves that the readout algorithm runs close to optimal precision (given by the Cramer-Rao bound) and provides a displacement readout similar to other interferometry–based displacement sensing techniques. These results show that using “deep–frequency modulation interferometry (DFMI)” based local displacement sensors can help current and future planned ground–based gravitational wave detectors to reach their target/design sensitivity in the low frequencies around 10−21 m/√Hz
Search for the production of a pair of highly Lorentz-boosted Higgs bosons via vector-boson fusion in final states with four bottom quarks with the ATLAS experiment
No full textA search for the production of a pair of Higgs bosons () via vector-boson fusion (VBF) in the Lorentz-boosted kinematic regime with subsequent decay of the Higgs bosons into four bottom quarks is presented. The analysis is based on 140~fb of proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider (LHC), at a center-of-mass energy of ~TeV.
The results were interpreted in terms of both non-resonant and resonant production of Higgs-boson pairs. Non-resonant VBF production is predicted by the Standard Model (SM); the production cross-section is, however, significantly enhanced for anomalous, non-SM values for the trilinear Higgs-boson self-coupling and the quartic coupling between two Higgs bosons and two vector bosons, parametrised as \kappa_{\l} and , respectively. Resonant VBF production is predicted only by extensions of the SM. In this thesis, the resonant production via the decay of a new heavy scalar particle originating from the vector-boson scattering was considered.
No significant deviation of the data from the expected background was observed. Hence, in the non-resonant search, limits on the and \kappa_{\l} couplings were set at confidence level. In the resonant search, upper limits on the signal cross-section were derived for intermediate masses ranging from 1.0~TeV to 5.0~TeV under the assumptions of a narrow- and broad-resonance widths. In the model-dependent broad-width scenario, a composite Higgs benchmark has been considered.
In addition to these results, which have been published in 2024, the relevant details of a successive on-going ATLAS analysis using additionally data collected in 2022 and 2023 at ~TeV and using more modern tools to identify the decays is discussed here.
Finally, a proof-of-principle study using a transformer-based machine-learning algorithm to discriminate signal from background events in triple Higgs-boson searches is also shown in this thesis. The even rarer production of three Higgs bosons has been gaining significant interest since it provides unique access to the quartic Higgs-boson self-coupling