Qucosa
Not a member yet
63150 research outputs found
Sort by
Der Zusammenhang zwischen Schlaf und Training bei jugendlichen Elite-Mannschaftsathleten in Österreich
No full textIn dieser Studie wurde das Schlaf-Wach-Verhalten jugendlicher Elite-Mannschaftsathleten in Österreich im Zusammenhang
mit deren Training untersucht. Dafür wurden 104 Athleten (M=14.52 Jahre, SD=0.40), die jeweils Mitglied eines U15/U16 Teams im
Fußball (n=69) oder Eishockey (n =35) waren, über mehrere Wochen (14–42 Tage) per Aktigraphie und Schlafprotokoll untersucht. Zusätzlich
wurden der Chronotyp (D-MEQ) und die allgemeine Schlafqualität (PSQI) erhoben. Es wurde angenommen, dass die Schlafqualität vor
Trainings- und Spieltagen geringer ist als vor Ruhetagen und dass sich eine geringe Schlafqualität negativ auf die Trainingsintensität auswirkt.
Es konnte gezeigt werden, dass die Athleten an Ruhetagen eine längere Schlafdauer aufweisen. Es hat sich außerdem bestätigt, dass
eine kürzere Schlafdauer und längere Einschlaflatenz einen negativen Einfluss auf die wahrgenommene Trainingsintensität am folgenden
Tag haben. Ein stärkerer Einbezug der Schlafqualität bei Leistungsanalysen und in der Gestaltung von Trainingsplänen wird empfohlen.This study investigates the sleep-wake behavior of elite youth team athletes in Austria concerning their training. For this purpose,
104 athletes (M = 14.52, SD = 0.40), who were each part of a U15/U16 soccer (n = 69) or ice hockey team (n = 35), were examined over 14–42
days using actigraphy and sleep protocol. In addition, we assessed chronotype (D-MEQ) and general sleep quality (PSQI). We hypothesized
that sleep quality before training and matchdays would be lower than before rest days, and that low sleep quality would negatively affect
training intensity. The study showed that athletes slept longer on rest days. It also confirmed that shorter sleep duration and longer sleep
onset latency negatively impact perceived training intensity the following day. A greater emphasis on sleep quality in performance analyses
and in the design of training plans is recommended
Evaluation of Preprocessing Methods on Independent Medical Hyperspectral Databases to Improve Analysis
No full textCurrently, one of the most common causes of death worldwide is cancer. The development of innovative methods to support the early and accurate detection of cancers is required to increase the recovery rate of patients. Several studies have shown that medical Hyperspectral Imaging (HSI) combined with artificial intelligence algorithms is a powerful tool for cancer detection. Various preprocessing methods are commonly applied to hyperspectral data to improve the performance of the algorithms. However, there is currently no standard for these methods, and no studies have compared them so far in the medical field. In this work, we evaluated different combinations of preprocessing steps, including spatial and spectral smoothing, Min-Max scaling, Standard Normal Variate normalization, and a median spatial smoothing technique, with the goal of improving tumor detection in three different HSI databases concerning colorectal, esophagogastric, and brain cancers. Two machine learning and deep learning models were used to perform the pixel-wise classification. The results showed that the choice of preprocessing method affects the performance of tumor identification. The method that showed slightly better results with respect to identifing colorectal tumors was Median Filter preprocessing (0.94 of area under the curve). On the other hand, esophagogastric and brain tumors were more accurately identified using Min-Max scaling preprocessing (0.93 and 0.92 of area under the curve, respectively). However, it is observed that the Median Filter method smooths sharp spectral features, resulting in high variability in the classification performance. Therefore, based on these results, obtained with different databases acquired by different HSI instrumentation, the most relevant preprocessing technique identified in this work is Min-Max scaling
Comorbid cerebral amyloid angiopathy in dementia and prodromal stages - Prevalence and effects on cognition
No full textObjectives:
To determine the contribution of cerebral amyloid angiopathy to cognitive impairment in MCI and dementia.
Methods:
Patients with subjective memory impairment (SMI), amnestic and non-amnestic mild cognitive impairment ((n)aMCI), Alzheimer's disease (AD), mixed and vascular dementia (MD/VD) from our memory clinic were included in this retrospective analysis. Patients underwent neuropsychological testing and cranial magnetic resonance imaging (MRI). Magnetic resonance imaging data sets were analyzed regarding the presence of CAA-related MRI biomarkers to determine CAA prevalence. ANOVAs were used to investigate the contribution of CAA to cognitive impairment within diagnostic groups and to determine whether differences in cognitive test performance between the diagnostic groups are mediated by total CAA burden.
Results:
475 patients (222 male, 253 female) with SMI (n = 47), naMCI (n = 41), aMCI (n = 189), early AD (n = 9), AD (n = 114), MD (n = 71) and VD (n = 4) were included. Mean age was 73.2 (9.9) years. CAA prevalence was 14.9% in SMI, 14.6% in naMCI, 24.3% in aMCI, 22.2% in early onset AD, 18.4% in late onset AD, 46.5% in MD and 25% in VD. Patients with possible and probable CAA were older than patients without CAA. In particular, diagnosis of aMCI, early onset AD, MD and VD showed high CAA prevalence. In AD but not in aMCI, CAA diagnosis significantly influenced test performance in the CERAD word list recall (F (1,78) = 4505; p = 0.037; partial eta-square = 0.055). Differences in cognitive test performance between the diagnostic groups of naMCI, aMCI, AD and MD were mediated by total CAA burden within AAT simply nouns subtest (F (2,39) = 4059; p = 0.025; partial eta-square = 0.172) and in CERAD verbal fluency test (F (3,129) = 3533; p = 0.017; partial eta-square = 0.076).
Conclusion:
This retrospective analysis demonstrates high prevalence rates of CAA in cognitive diagnoses. Our data suggest that comorbid CAA independently impacts cognitive test performance in the course of AD with presumably stage-dependent effects. Especially in patients with AD comorbid CAA additionally impairs memory function. Total CAA small vessel disease burden further modulates psychometric differences in cognitive test performance between diagnostic groups regarding word finding and word fluency capabilities
Franz Metz, In E-Dur. Otto Sykora und die heitere Musikgeschichte des Banater Berglands, München: Edition Musik Südost, 2023. 288 S., Abb.
No full textSolving general Twisty Puzzles with Reinforcement Learning and automatic Algorithm Generation
No full textThe Rubik's Cube and hundreds of twisty puzzles that were made afterwards have challenged millions of people around the world for decades. Coming up with new solution strategies for a twisty puzzle can be very difficult and often takes even experienced humans many hours.
Recently, Machine Learning has been used to find new solutions to such puzzles with little to no human knowledge required. But these solutions are difficult for humans to replicate as there is little obvious structure.
We propose a method to automatically generate algorithms for puzzles and use them to augment the action set of reinforcement learning agents. The augmented action set enables learning with an intuitive, dense reward function and the resulting agents learn more interpretable solution strategies while using significantly less compute than previous methods to solve the Rubik's Cube.:1 Introduction and motivation 1
1.1 Related work 3
1.2 Mathematical Foundation 4
1.2.1 Permutations 4
1.2.2 Modeling Twisty Puzzles 4
1.2.3 Group Properties of non-bandaged Twisty Puzzles 6
2 Algorithm generation 7
2.1 Automatic Symmetry Detection 8
2.2 Automatic Piece Detection 11
2.3 Algorithm Generation 14
2.4 Reinforcement Learning 18
3 Experiments and Results 21
3.1 Experiment Description 22
3.1.1 Research Questions 22
3.1.2 Investigated Puzzles 22
3.2 Results and Discussion 27
3.2.1 Training behavior 27
3.2.2 Training Time Scaling with State Space Size 28
3.2.3 Policy Analysis 30
3.2.4 Limitations 39
3.3 Further questions 40
3.4 Conclusion 42
A Compute Hardware & training time 47
B Alternative Symmetry Detection 4
Lagrangian Studies of Arctic Air Mass Transformations During Warm Air Intrusions and Cold Air Outbreaks
No full textIn den letzten 30-40 Jahren hat sich das arktische Klimasystem dramatisch verändert. Phänomene wie der schnelle Rückgang des arktischen Meereises und die beschleunigte Zunahme der oberflächennahen Lufttemperaturen sind wesentliche Kennzeichen der arktischen Verstärkung des Klimawandels, verursacht durch verschiedene Rückkopplungsmechanismen. Der polwärts gerichtete Transport latenter Wärme, hauptsächlich durch Warmlufteinschübe (WLE), hat deutlich zugenommen. In entgegengesetzter Richtung bezeichnen marine Kaltluftausbrüche (KLA) den südwärts gerichteten Transport kalter und trockener arktischer Luftmassen. Sowohl WLE als auch KLA haben große Auswirkungen auf das arktische Klimasystem, doch ihre begleitenden Luftmassentransformationen sind noch nicht vollständig verstanden und quantifiziert. Um diese Lücke zu schließen, kombiniert diese kumulative Dissertation neuartige Lagrange’sche (Luftmassen-folgende) Trajektoranalysen mit atmosphärischen Reanalysen und Beobachtungen von drei kürzlich durchgeführten arktischen Expeditionen.
In Paper I (Kirbus et al., 2023a) wird ein WLE Mitte April 2020 analysiert. Messungen der Expedition Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) zeigen einen raschen Anstieg der 2-m Lufttemperatur um etwa 30K in zwei Tagen und einen anomalen Erwärmungseffekt auf das Energiebudget der Oberfläche. In einem neuen methodischen Ansatz wird die Entwicklung nahezu aller Luftmassen, welche über MOSAiC enden, sowie die relevanten Prozesse und Luftmassentransformationen ausgewertet.
Für Paper II (Kirbus et al., 2023b) wird ein komplexer KLA im Herbst 2020 erforscht. Die gleiche Luftmasse wurde zuerst in der Zentralarktis durch MOSAiC und zwei Tage später in der eisfreien Framstraße durch die Kampagne MOSAiC Airborne observations in the Central Arctic (MOSAiC-ACA) beobachtet. Eine atmosphärische Reanalyse wird genutzt, um die zeitliche Entwicklung der Luftmasse nachzuvollziehen. Darüber hinaus werden Temperatur- und Feuchtetendenzen genutzt, um die Luftmassentransformationen während des Drifts zu untersuchen. Entgegen der Erwartung werden diese Transformationen nicht nur durch Oberflächenveränderungen (Meereis zu offenem Ozean) beeinflusst, sondern auch durch differentielle Advektion von Wolken und Wasserdampf. Die Bedeutung von Windscherung und vertikaler Interaktionen wird hervorgehoben.
Paper III (Kirbus et al., 2024a) untersucht einen intensiven KLA während der HALO-(AC)³-Kampagne im Frühjahr 2022. Die praktizierte quasi-Lagrange’sche Flugstrategie erlaubt die Quantifizierung der diabatischen Erwärmung, Feuchteaufnahme und gleichzeitigen Wolkenentwicklung entlang des KLA. Durch den Vergleich von zwei Reanalysenprodukten mit den Beobachtungen werden Herausforderungen bei der Darstellung der Randeiszone, des turbulenten Wärmeflusses, sowie von Wolken- und Niederschlagsbildung aufgedeckt.
Abschließend wird die quasi-Lagrange’sche Auswertung auf die gesamte HALO-(AC)³-Kampagne ausgedehnt, was zu einem umfangreichen Datensatz von mehrfach beobachteten Luftmassen führt (Kirbus et al., 2024b,c). Ergebnisse aus Paper IV (Wendisch et al., 2024) geben einen statistischen Überblick über diese quasi-Lagrange’schen matches, sowie über diabatische Erwärmung/Abkühlung und Feuchtigkeitsänderungen innerhalb arktischer WLE und KLA.:Overview of Research Articles by Benjamin Kirbus
Contributions of Benjamin Kirbus to Papers I-IV
Supervision Statement
1 Air Mass Transformations in a Changing Arctic Climate System
1.1 Arctic Amplification
1.1.1 Arctic Climate Changes
1.1.2 Feedback Mechanisms
1.1.3 Role of Meridional Transport
1.2 Warm and Moist Air Intrusions
1.3 Marine Cold Air Outbreaks
1.4 Research Questions
2 Methods
2.1 Observations
2.1.1 Shipborne Measurements
2.1.2 Airborne Measurements
2.2 Trajectory Calculations
2.2.1 Eulerian versus Lagrangian Viewpoints
2.2.2 Trajectory Models
2.2.3 Challenges and Mitigation Strategies
2.3 Reanalysis Data
2.3.1 ERA5
2.3.2 CARRA
3 Results
3.1 Paper I – Pathways and Governing Processes of an Arctic WAI Observed
During MOSAiC
3.1.1 Motivation and Methods
3.1.2 Impacts at the MOSAiC Site
3.1.3 Investigation of Air Mass Pathways
3.2 Paper II – An Autumn CAO Forced by Surface Changes and Vertical Interactions
Through Advection in Higher Altitudes
3.2.1 Motivation and Methods
3.2.2 Thermodynamic and Cloud Evolution
3.2.3 Investigation of the Transformation Processes and Vertical Interactions
3.3 Paper III – Quasi-Lagrangian Thermodynamic and Cloud Evolution From Observations
Compared to Reanalyses
3.3.1 Motivation and Methods
3.3.2 Spatial Overview and Thermodynamic Profiles
3.3.3 Diabatic Heating and Moistening
3.4 Paper IV – Observed Diabatic Heating/Cooling and Moisture Changes During
All WAIs and CAOs of HALO-(AC)³
3.4.1 Motivation and Methods
3.4.2 Statistics on Matching Trajectories
3.4.3 Diabatic Heating/Cooling and Moisture Changes in WAIs and CAOs
4 Summary and Outlook
References
List of Abbreviations
List of Symbols
List of Figures
List of Tables
Acknowledgments
Curriculum Vitae
Appendix A: Paper I
Appendix B: Paper II
Appendix C: Paper III
Appendix D: Paper IVIn the last 30-40 years, the Arctic climate system has undergone dramatic changes. Phenomena like the rapid decline of Arctic sea ice and enhanced increase of near-surface air temperatures compared to the globe are key signatures of the Arctic amplification of climate change, caused by various local and remote feedback mechanisms. Poleward transport of latent heat, primarily through episodic warm and moist air intrusions (WAIs), has increased considerably. In opposite direction, marine cold air outbreaks (CAOs) denote the southward transport of cold and dry Arctic air masses. Both WAIs and CAOs have large impacts on the Arctic climate system, yet their accompanying air mass transformations are not fully understood and quantified. To investigate the mechanisms shaping WAIs and CAOs, this cumulative dissertation combines novel Lagrangian (air mass following) trajectory analysis with atmospheric reanalyses and observations from three recent Arctic expeditions.
In Paper I (Kirbus et al., 2023a), an intense WAI occurring in mid-April 2020 is analyzed. Measurements from the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition show a rapid rise of the 2-m air temperature by about 30K within two days, and an anomalous heating effect on the surface energy budget (SEB). A novel methodological approach is developed to investigate the air mass pathways during the WAI, tracing the evolution and transformation mechanisms of virtually all air masses ending above the MOSAiC site. The impact of the WAI on the SEB is investigated based on reanalysis data and observations both during the poleward drift, as well as at the MOSAiC site.
For Paper II (Kirbus et al., 2023b), a complex CAO occurring in autumn 2020 is explored, where the same air mass was first observed in the central Arctic during MOSAiC, and then two days later over the ice-free waters of Fram Strait as part of the MOSAiC Airborne observations in the Central Arctic (MOSAiC-ACA) campaign. The temporal evolution of the air mass is traced using reanalysis output, while reanalysis-derived temperature and humidity tendencies are utilized to explore the air mass transformations along the pathway. Contrary to expectations, the air mass transformations are not solely driven by surface changes from sea ice to open ocean, but also impacted by differential advection of clouds and water vapor across the near-surface flow. The relevance of wind shear and vertical interactions is therefore highlighted.
Paper III (Kirbus et al., 2024a) investigates a strong Arctic CAO observed during the HALO-(AC)³ campaign in spring 2022. For the first time, airborne observations gathered using a dedicated quasi-Lagrangian flight strategy enable a quantification of diabatic heating, moisture uptake, and concurrent cloud evolution along a CAO. By confronting two reanalysis products with the observations, their challenges with representing the marginal sea-ice zone, surface turbulent heat fluxes, clouds, and precipitation are revealed.
Finally, the quasi-Lagrangian analysis is extended to the whole HALO-(AC)³ campaign, resulting in a large dataset of matching air masses (Kirbus et al., 2024b,c). Paper IV (Wendisch et al., 2024) provides a statistical overview of these quasi-Lagrangian matches, as well as of diabatic heating/cooling and moisture changes within Arctic WAIs and CAOs.:Overview of Research Articles by Benjamin Kirbus
Contributions of Benjamin Kirbus to Papers I-IV
Supervision Statement
1 Air Mass Transformations in a Changing Arctic Climate System
1.1 Arctic Amplification
1.1.1 Arctic Climate Changes
1.1.2 Feedback Mechanisms
1.1.3 Role of Meridional Transport
1.2 Warm and Moist Air Intrusions
1.3 Marine Cold Air Outbreaks
1.4 Research Questions
2 Methods
2.1 Observations
2.1.1 Shipborne Measurements
2.1.2 Airborne Measurements
2.2 Trajectory Calculations
2.2.1 Eulerian versus Lagrangian Viewpoints
2.2.2 Trajectory Models
2.2.3 Challenges and Mitigation Strategies
2.3 Reanalysis Data
2.3.1 ERA5
2.3.2 CARRA
3 Results
3.1 Paper I – Pathways and Governing Processes of an Arctic WAI Observed
During MOSAiC
3.1.1 Motivation and Methods
3.1.2 Impacts at the MOSAiC Site
3.1.3 Investigation of Air Mass Pathways
3.2 Paper II – An Autumn CAO Forced by Surface Changes and Vertical Interactions
Through Advection in Higher Altitudes
3.2.1 Motivation and Methods
3.2.2 Thermodynamic and Cloud Evolution
3.2.3 Investigation of the Transformation Processes and Vertical Interactions
3.3 Paper III – Quasi-Lagrangian Thermodynamic and Cloud Evolution From Observations
Compared to Reanalyses
3.3.1 Motivation and Methods
3.3.2 Spatial Overview and Thermodynamic Profiles
3.3.3 Diabatic Heating and Moistening
3.4 Paper IV – Observed Diabatic Heating/Cooling and Moisture Changes During
All WAIs and CAOs of HALO-(AC)³
3.4.1 Motivation and Methods
3.4.2 Statistics on Matching Trajectories
3.4.3 Diabatic Heating/Cooling and Moisture Changes in WAIs and CAOs
4 Summary and Outlook
References
List of Abbreviations
List of Symbols
List of Figures
List of Tables
Acknowledgments
Curriculum Vitae
Appendix A: Paper I
Appendix B: Paper II
Appendix C: Paper III
Appendix D: Paper I
As climate changes, everything changes
No full textTheoretical and Applied Climatology (TAAC) has recently undergone a few changes. These include the editorial management system SNAPP (https://www.springernature.com/gp/snapp) and an enlarged Editorial Board (https://www.springer.com/journal/704). As the new managing editor, I would like to address these changes and set them in perspective to the developments in climate research and in the related publishing sector
Vibrational spectroscopy and multiphoton microscopy for label‑free visualization of nervous system degeneration and regeneration
No full textNeurological disorders, including spinal cord injury, peripheral nerve injury, traumatic brain injury, and neurodegenerative diseases, pose significant challenges in terms of diagnosis, treatment, and understanding the underlying pathophysiological processes. Label-free multiphoton microscopy techniques, such as coherent Raman scattering, two-photon excited autofluorescence, and second and third harmonic generation microscopy, have emerged as powerful tools for visualizing nervous tissue with high resolution and without the need for exogenous labels. Coherent Raman scattering processes as well as third harmonic generation enable label-free visualization of myelin sheaths, while their combination with two-photon excited autofluorescence and second harmonic generation allows for a more comprehensive tissue visualization. They have shown promise in assessing the efficacy of therapeutic interventions and may have future applications in clinical diagnostics. In addition to multiphoton microscopy, vibrational spectroscopy methods such as infrared and Raman spectroscopy offer insights into the molecular signatures of injured nervous tissues and hold potential as diagnostic markers. This review summarizes the application of these label-free optical techniques in preclinical models and illustrates their potential in the diagnosis and treatment of neurological disorders with a special focus on injury, degeneration, and regeneration. Furthermore, it addresses current advancements and challenges for bridging the gap between research findings and their practical applications in a clinical setting
Association between maternal employment and the child´s mental health: a systematic review with meta‑analysis
No full textThe recent rise in maternal workforce participation has led to more research regarding the role of maternal employment for (early) childhood mental health. This systematic review with meta-analysis covers new evidence on the association of both variables. A systematic literature search was conducted. Studies had to compare children 0–7 years of age on the basis of their mothers’ employment status, working amount, employment duration, i.e., how long the mother had been back at work after birth, or timing of return to work. Child mental health was operationalized as behavior problems and prosocial behavior. Narrative and meta-analytic syntheses of evidence were conducted. Maternal employment was associated with more conduct problems but less internalizing behavior problems and anxious/depressed behavior in children; full-time employment was linked to more externalizing behavior problems and more hyperactivity/inattention. Longer employment duration was related to less (internalizing) behavior problems and more prosocial behavior but also more externalizing behavior problems. Narrative syntheses indicated early maternal return to work to be associated with more child externalizing behavior problems and less prosocial behavior. Whether maternal employment is associated with child mental health strongly depends on both variables’ operationalization. Especially part-time employment, longer employment duration, and return to work only after the first year postpartum may be beneficial for child mental health. Practical implications pertain to an expanded offer of family leave and the endorsement of maternal employment after the first year postpartum. Here, factors that may buffer the negative associations with full-time employment warrant consideration