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The development of low-cost photoacoustic gas sensor devices for monitoring ozone and nitrogen dioxide and the quantification of gas composition through changes in the speed of sound
Get PDFThe dissertation aimed to develop a low-cost gas detection sensor utilizing photoacoustic spectroscopy (PAS). This technique exploits the photoacoustic (PA) effect, where target molecules absorb modulated light at a specific wavelength. When these molecules absorb optical energy, they become excited and subsequently relax to the ground state. This results in the release of the heat, generating pressure waves or sound known as the photoacoustic signal. This signal is then detected by a sensitive detector, such as a microphone, or quartz tuning fork [1].
This dissertation comprises four published articles. The first article investigated the use of a piezoelectric tube, serving as a dual function resonance tube and transducer for detecting nitrogen dioxide (NO2). In this study, a 450 nm blue laser diode with a maximum power output of 1800 mW was employed as the light source. The photoacoustic system exhibited sufficient sensitivity for measuring NO2 gas in the part per billion (ppb) range. This innovative approach offers an alternative method for gas analysis based on photoacoustic technique.
The second article presented a novel approach for measuring ozone (O3) using a visible laser diode with a wavelength of 638 nm, targeting the Chappuis bands of ozone in the spectral range of 380-800 nm [2]. Ozone absorbs light most strongly in the UV region (200-350 nm), which falls into the Hartley band [3]. However, commercially available low-power LEDs are not sensitive enough to detect ozone at low concentrations in UV band, and using lasers is expensive. An alternative method involves using a higher power red laser diode to compensate for the weaker ozone absorption in Chappuis region. Within this study, the photoacoustic cell was constructed from stainless steel, following a design similar to that previously reported by Rück et al [4]. To pick-up the generated acoustic signal, a micro-electrical mechanical system (MEMs) microphone was employed. The minimum detectable concentration of ozone using this setup was in the part per million (ppm) range, comparable to previous studies that used a Nd:YAG laser in the same wavelength region, as reported by Köhring et al. [5].
The third project aimed to contribute to the advancement of photoacoustic gas monitoring by developing a low-cost photoacoustic circuit module that could replace an expensive commercial instrument. This module, comprising a 32-bit microcontroller, waveform generator, laser diode driver, lock-in amplifier, and an analog-to-digital converter, were integrated onto a single printed circuit board (PCB). The system was operated through a Python graphical user interface (GUI) for controlling the module and acquiring data. The acquired data was collected as a text file, allowing it easy to integrate with software such as Microsoft Excel or Igor for further analysis. This device was implemented as a photoacoustic sensor for NO2 detection, with a detection limit in the ppb range. This circuitry costs twenty times less than that of commercial instruments. Its compact design also makes it favorable for future development in onsite applications.
The fourth project aimed to present a novel quantitative method for determining the composition of gas mixtures through the change in the speed of sound. The focus was on measuring the resonance frequency of binary gas mixtures (O2/N2, CO2/N2, and He/N2) at various compositions. The experiments utilized a piezoelectric transducer serving as both an acoustic resonator and a detector. A loudspeaker was utilized as an audio excitor in photoacoustic process. At different compositions in gas mixture, the resonance frequency varied due to the differences in the speed of sound in each gas sample. This analytical approach to the changes in resonance frequency make it possible to estimate the composition of the gas mixture. It provides a useful tool for understanding and quantifying gas compositions in various gas applications
Mechanical excitation of trapped ions coupled to a nanomechanical oscillator
Get PDFLaser-cooled ions confined in radiofrequency traps count among the best controllable quantum
systems with applications in fields such as spectroscopy, ultracold chemistry and quantum tech-
nologies. They offer a variety of well-established techniques for the manipulation and readout of
their internal and external quantum states and exhibit excellent coherence properties. Nanome-
chanical oscillators are solid-state objects on the nanometer scale. Their small sizes make them
excellent candidates for the study of the interface between classical and quantum physics and the
cooling and manipulation of their motion on the single-phonon level has recently been achieved.
Nanomechanical oscillators are highly sensitive transducers, making them excellent sensors for
small forces with famous applications such as atomic force microscopy. The combination of
different types of physical systems into a single hybrid system has been of increasing interest
in recent years. The goal is to exploit the individual advantages of the constituents in order to
develop new applications and techniques that the individual systems alone could not provide.
Hybrid systems coupling trapped ions to a charged nanomechanical oscillator may offer novel
techniques for the bidirectional manipulation and readout of the quantum states of motion of
both constituents. The subsystems are coupled by the electrostatic interaction of their charges
and act as coupled harmonic oscillators. By resonantly driving the ions with driven vibrations
of the nanomechanical oscillator, strong coupling can be achieved and the motional state of the
ions can be manipulated. Here, we present the successful coupling of trapped 40Ca+ ions to a
charged Ag2Ga nanowire in an ion-nanowire hybrid system in the classical regime. We present
a theoretical description for the classical dynamics of the resonantly driven ion motion and
support the results with numerical simulations. We simulate and experimentally investigate
the static effects of the charged nanowire on the trapping potential. We present experimental
results for the resonant excitation of the ion motion with the mechanically driven nanowire and
show the effects on the coupling strength for the variation of different coupling parameters
IL-1β in health and diseases: bridging adipogenesis to systemic inflammation
No full textExtensive research has investigated the role of IL-1β as a pivotal cytokine mediating immune-related host-defence mechanisms. It has been described that chronic exposure IL-1β, as observed in obesity, inhibits adipogenesis and contributes to systemic inflammation. In the first manuscript, our work introduces the notion that IL-1β acutely plays a physiological role in promoting adipogenesis. Through in vitro and in vivo experiments, we demonstrate that acute exposure to IL-1β, such as observed postprandially, promotes adipogenesis, particularly in early-differentiation-stage adipocyte progenitor cells. Further, we demonstrate that obesity and chronic inflammation, resulting from overnutrition, shift the physiological role of IL-1b to an inflammatory pathological process. In the second manuscript of this thesis, we conduct a comparative analysis of clinical parameters, fatty acid profiles, immune cell subsets, and inflammatory responses of peripheral blood mononuclear cells (PBMCs) obtained from both healthy individuals and those diagnosed with type-2 diabetes (T2D). We show that patients with T2D exhibit mild systemic inflammation. Surprisingly, we did not detect significant alterations in pro-inflammatory profile of PBMCs nor shifts in the immune cell population of our study participants. However, the total number of immune cells was increased in the circulation of individuals with T2D. Thus, we conclude that the observed systemic inflammation is likely due to the elevated number of circulating leukocytes rather than an elevated proinflammatory profile of these circulating cells. Furthermore, we show that pharmacological inhibition of caspase-1 and NLRP3 blunted IL-1b secretion by PBMCs. Thus, our findings suggest that inhibition of NLRP3 inflammasome components are promising therapeutic approaches for managing diabetes and its associated comorbidities
Die praktische Anwendbarkeit von primären und sekundären Ausbelastungskriterien von VO2max in der Spiroergometrie bei Kindern
No full textDie maximale Sauerstoffaufnahme (VO2max) ist weltweit als die beste Messgrösse für aerobe Fitness anerkannt. Primäres Kriterium für ihre Identifizierung ist die Erreichung eines VO2 Plateaus am Ende der Anstrengung, das jedoch bei Erwachsenen und Kindern selten zu beobachten ist. Aus diesem Grund werden als sekundäre Kriterien die maximale respiratory exchange ratio (RERmax), die maximale Herzfrequenz (HFmax), Blutlaktatkonzentration und ratings of perceived exertion (RPE) herangezogen, um eine mögliche Ausbelastung festzustellen. Aufgrund der fehlenden wissenschaftlichen Etablierung der Cutoff-Werte dieser Kriterien für Kinder, ist deren Interpretation komplexer.
In dieser Arbeit wurde die Nützlichkeit und praktische Anwendbarkeit dieser Kriterien bei Kindern weiter zu untersucht, um die Unterschätzung der VO2max zu minimieren und die Interpretation der Ausbelastung zu verbessern.
25 Kinder (7-10 Jahre) und 39 Erwachsene (20-31 Jahre, >4 Stunden Sport pro Woche) unterzogen sich einer Spiroergometrie. Ihre primären und sekundären Kriteriumswerte wurden mittels deskriptiver Statistik und kritischer Diskussion analysiert.
Die Analysen ergaben ein Fehlen grosser Variationen in den sekundären Kriteriumswerten bei den Kindern, eine Differenz zu den Erwachsenenwerten und eine Seltenheit beim Erreichen des Plateaus. Der Vergleich mit den Cutoff-Werten in der Literatur zeigte, dass die Mehrheit der Kinder diese für RERmax und HFmax überschritt, nicht jedoch für die Blutlaktatkonzentration.
Diese Ergebnisse legen nahe, dass sich die Berücksichtigung dieser sekundären Kriterien bei Kindern als nützlich erweisen könnte, um eine präzisere Ausbelastung und praktische Anwendbarkeit für die RERmax und HFmax zu etablieren. Für eine genauere Interpretation ist es jedoch weiterhin notwendig, eine wissenschaftliche Etablierung für diese Cutoff-Werte zu finden
Akute Effekte einer 20-minütigen, moderat intensiven Ausdauereinheit auf das Risikoverhalten von jungen Erwachsenen in einer computergestützten Glücksspielaufgabe
No full textHintergrund: Risikoverhalten ist ein entscheidender Faktor für die Gesundheit und ein für die Gesellschaft relevantes Thema. Unter anderem wird das riskante Verhalten durch die heissen Parameter der Exekutiven Funktionen (EF) bedingt. Im Gegensatz zu den kalten EF, welche in neutralen Situationen zum Einsatz kommen, werden die heissen EF in emotional und motivational geprägten Situationen genutzt. Es ist bekannt, dass akute körperliche Aktivität einen positiven Einfluss auf die kalten EF ausübt. Ob dies für die heissen EF gilt, ist noch unklar. Die Iowa Gambling Task (IGT) kann genutzt werden, um die heissen EF in riskanten Situationen zu testen. Schlechtere Leistungen der IGT zeugen von riskanterem Verhalten.
Methoden: Die Probandinnen und Probanden wurden randomisiert einer Interventions- und einer Kontrollgruppe zugeteilt. Beide Gruppen absolvierten zwei Mal die IGT (Prä und Post). Zwischen den beiden Messzeitpunkten führte die Interventionsgruppe eine 20-minütige, moderat intensive Ausdauereinheit (Laufband) durch, während die Kontrollgruppe 20 Minuten lang ein Video schaute. Zur Analyse von Unterschieden in der Veränderung von Prä- zu Post zwischen den Gruppen, wurden vier verschiedene Modelle der ANOVA verwendet.
Ergebnisse: Eine 20-minütige, moderat intensive Ausdauereinheit führte zu keinen statistisch signifikanten Verbesserungen des riskanten Verhaltens bei jungen Erwachsenen im Vergleich zu einer Kontrollgruppe. Allerdings zeigte die Interventionsgruppe eine Verringerung des riskanten Verhaltens von Prä zu Post
Schlussfolgerungen: Obwohl die Resultate keine statistisch signifikanten Unterschiede zwischen den Gruppen feststellten, gab es Indizien dafür, dass akute körperliche Aktivität die heissen EF verbessert. Weitere Forschung zu den Effekten akuter körperlicher Aktivität auf die heissen EF ist notwendig
Pronatalist policies’ backlash in authoritarian regimes
Get PDFEuropean fascist regimes have attached great importance to nationalistic families and designed policies to perpetuate them. Most offered policy packages with interest-free loans repayable through childbirth, along with allowances and tax deductions for large families. Using a difference-in-difference approach and Nazi Germany as a case study, we show that these policies may have counterproductive effects due to negative selection mechanisms in the marriage market. The excessive pressure to marry exerted on singles results in lower quality, ultimately less fertile, and more fragile unions. This finding is important as the main European far-right parties today propose reinstating these policy packages
The Political Economy of Attention and Electoral Accountability
Get PDFIn this survey, we investigate the general mechanisms underlying the political economy of attention and review their empirical relevance, in particular for electoral accountability. The focus is on exogenous or stimulus-driven attention that political actors try to win or divert when pursuing their private interests. The corresponding evidence refers to representatives’ reactions to general shifts in media attention and persuasive content as well as to short-term fluctuations in attention when exploiting anticipated attention shifts or attention shocks. In the context of digitization and the Internet, we consider the substitution effects between alternative media sources, the role of algorithmic content selection in informational segregation (or echo chambers), and the new opportunities of individual-level targeting strategies to steer attention
The spectrum of personality pathologies: zooming in on transdiagnostic dimensionality and operationalization in time-limited practice
Get PDFCategorical personality disorder (PD) models have been rejected in favor of alternative
dimensional approaches by the DSM-5 Alternative Model for Personality Disorder (AMPD) in
and the ICD-11 classification. This has resulted in numerous studies testing the empirical
validity of the DSM-5 AMPD and ICD-11 approaches, including transdiagnostic indicators.
While well-validated self-reports support the operationalization of these dimensional
approaches, (semi)-structured interviews are considered the gold standard for the assessment
of PD. However, given the time constraints in clinical practice, there is a need to identify core
dimensions of personality pathology to get directly to the essence of PD.
Therefore, the present thesis focuses on the empirical foundation of three aspects of
dimensional PD approaches. First, we sought to examine the impact and transdiagnostic
overlap between potential personality pathologies and other mental disorders, e.g.,
somatization. Therefore, we conducted a systematic literature search to identify and synthesize
the evidence of convergence between personality dysfunctions and somatization disorder.
Additionally, existing concepts of somatization were crucially reflected in the context of the
DSM-5 AMPD (Study I). Second, we focused on the operationalization of personality
functioning according to DSM-5 AMPD. Therefore, we translated and evaluated the
psychometric properties of a self-report questionnaire – the Self and Interpersonal Functioning
Scale (SIFS). We then conducted and analyzed a large multi-method dataset from different
non-clinical and clinical samples and evaluated the structure, reliability, validity, and loading
pattern of the SIFS (Study II). Third, we sought to evaluate core dimensions of personality
dysfunction that can provide clinical approximation of the personality dysfunction severity in
time-limited practice. To this end, we used the data of a multi-method design consisting of
well-validated (semi-)structured interview and self-report ratings of personality functioning,
personality organization, and personality structure to calculate a latent method-adjusted general
factor of personality dysfunction severity (g-PDS; Study III).
Study I showed that PDs and personality pathologies are in fact often comorbid in
subjects suffering from somatization. Whereas categorical PD diagnosis models revealed
unspecific results, dimensional PD diagnostic approaches showed high associations with
somatization in the following personality dimensions: pathologies of the self, negative
affectivity harm avoidance, and self-defeating traits. This underlines the need to develop easily
applicable instruments for the assessment of DSM-5 AMPD personality functioning across
various mental disorders. In Study II, the German version of the SIFS self-report questionnaire could be such an easy-to-use instrument; nevertheless, our results indicate that it warrants
modifications for the use in research. However, a 22-item adapted version can be used as a
self-report questionnaire in clinical practice. Its psychometric properties in assessing the
general personality disorder (g-PD) factor are sufficient, but it shows insufficient structural
validity for the specific factors. Study III showed that among the variety of interview-rated
dimensions four PDS dimensions – defense mechanisms, desire and capacity for closeness,
sense of self with boundaries to others, and understanding and appreciation of experiences and
motivations of others – efficiently approximate the latent, method-adjusted g-PDS with 95.0%
explained variance. When combining two of these four dimensions, between 81.8% and 91.3%
of the latent g-PDS variance can be explained. Of note, measures of defense mechanisms are
lacking in the conceptualizations of the ICD-11 and DSM-5 AMPD. Regarding self-report
dimensions, we recommend assessing at least the identity and intimacy subdomains of
personality functioning.
Taken together, our studies establish that the assessment of personality functioning has
an important transdiagnostic value to somatization pathologies and their treatment. To facilitate
the diagnostic process, the SIFS can be used for a global impression of the level of personality
functioning, but should be used with caution in research. Finally, in time-limited practice, a
special emphasis should be placed on self-report and interview-assessed subdomains of identity
and intimacy to approximate the g-PDS. Furthermore, our results highlight the relevance of old
psychodynamic concepts, such as defense mechanisms, in contemporary transdiagnostic
personality pathology research
Chemical vapour transport in open systems: a technique for the "in situ" control of crystal morphologies in iron- and cobald silicides
No full textThis dissertation addresses chemical vapor transport (CVT) for producing nanostructured materials. To date, the lack of a comprehensive understanding of nanowire growth has hindered the potential integration of advanced metal silicide structures into semiconductor technology.
This study aimed to define the thermodynamic reaction conditions necessary for forming one-dimensional structures within the Fe-Si-I and Co-Si-I transport systems. To elucidate aspects of the nanowire formation mechanism, CVT reactions of all chemical species in these systems were investigated. The transport systems were adapted into an open CVT system, derived from the original “Mitführmethode”, to compare, for the first time, experimental results of binary phase materials with thermodynamic predictions, calculated using the Gmin-method (TRAGMIN software).
The experiments focused on three key parameters: source supply type, growth substrate, and flow rate, revealed limitations of the thermodynamic model, particularly due to the unaccounted saturation effect. Furthermore, crystal analysis showed that flow rate played a crucial role in controlling composition and morphology, enabling targeted growth regulation.
Through this parameter study, one-dimensional crystal growth was linked to the presence of liquid metal iodides. Liquid-assisted nucleation and growth pointed toward a vapor-liquid-solid (VLS) mechanism. Additionally, transport conditions of supersaturation were compared with universal growth behaviors observed in snowflake studies. The findings indicate that nanostructured growth processes are fully accessible through conventional CVTs, enabling in situ control of growth morphology throughout the process. In conclusion, this investigation presents promising opportunities to fine-tune metal silicides for applications in electronics and photovoltaics
Ethical considerations in paediatric genome-wide sequencing
Get PDFThis thesis presents research conducted between 2018 and 2023, addressing various ethical challenges related to paediatric genome-wide sequencing, with a particular focus on the clinical contexts in Germany and Switzerland.
Chapter One serves as an introductory section, establishing the foundational context for the subsequent chapters. It delineates the rapid advancements which the ability to investigate the human genome has undergone in the last decades and underscores their profound impact on medical genetics. Furthermore, it explains the scientific fundamentals surrounding genome-wide sequencing and provides an initial glimpse into the associated ethical challenges. The latter remains concise, as Chapter Three provides an extensive literature review of ethical aspects. Chapter One then sheds light on the research gaps, which this project has addressed. Finally, this initial chapter outlines the research objectives of this thesis.
Chapter Two offers an overview of the methodological approaches employed in this research to achieve the previously outlined objectives. It concentrates on those aspects which are not covered in the methods sections of the research articles themselves. Subsequently, the chapter provides an overview of the individual contributions made within this study.
Chapter Three presents a systematic qualitative review encompassing the full spectrum of ethical considerations in paediatric genome-wide sequencing, as discussed in the normative and empirical literature. It provides a comprehensive ethics matrix cataloguing 106 identified ethical issues, underscoring the substantial amplification of ethical challenges compared to traditional genetic testing. The chapter emphasises the importance of fostering awareness regarding the possibilities and challenges posed by genome-wide sequencing, also within non-genetic specialities.
Chapter Four explores the intricacies associated with obtaining ethically sound informed consent for paediatric genome-wide sequencing. The qualitative analysis of interviews with Swiss and German medical geneticists highlights their concerns regarding the validity of parents’ informed consent due to the extensive information given and the complexity of possible test outcomes. The study concludes that shifting expectations from the conventional ideal of fully informed consent to a more realistic and ethically sound model of appropriate informed consent is necessary.
Chapter Five provides insights into the perspectives and experiences of medical geneticists in Germany and Switzerland regarding the concept of non-directiveness. The analysis reveals significant uncertainties and divergences in their understanding and application of the concept. The study concludes that an adequately nuanced understanding and application of non-directiveness is crucial to circumvent the risks inherent in the principle, while simultaneously promoting patient autonomy and beneficence.
As a theoretical endeavour, Chapter Six introduces the concept of considering parents of seriously ill children as secondary patients. This could serve to raise awareness about the profoundly interacting and interdependent vulnerabilities of paediatric patients and their parents and could also be instrumental in advocating for increased support. The chapter concludes that the notion of secondary patients represents a significant stride towards acknowledging the relational nature of healthcare more generally.
Chapter Seven presents the results of the qualitative study with medical geneticists in Germany and Switzerland surrounding the reimbursement of paediatric exome sequencing. It reveals that participants highlighted the frequent lack of reimbursement by health insurers and related legal aspects as a significant problem, imposing a substantial administrative burden, leading to significant injustices, and undermining clinical decision-making. The chapter offers a comprehensive analysis of the legal framework as well as of the underlying ethical concepts and advocates for a broader perspective on therapy and health.
Chapter Eight expands upon the discourse concerning fair, equitable, and consistent reimbursement, broadening the scope from diagnostics to include reimbursement for orphan medicinal products. Employing the systematic review of reasons methodology, this chapter offers a systematic analysis of the moral arguments both in favour of and against granting orphan medicinal products special status when considering them for reimbursement within publicly funded healthcare systems. Chapter Eight contends that on a normative-theoretical level, there is no clear-cut solution for this challenge and provides suggestions what the scientific discourse and health technology assessments should focus on instead.
Finally, in Chapter Nine a general discussion of the key results of thesis is presented, highlighting their significance and implications. Additionally, it sketches out critical topics of major relevance in the context of paediatric genome-wide sequencing which warrant further research. As this project could not empirically investigate parental perspectives, Chapter Nine then offers a concise overview of studies conducted with parents in other countries. After addressing general limitations of the research conducted, Chapter Nine ends with some concluding remarks