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Theoretical estimates for measured quantities

Sozial- und geisteswissenschaftliche (SGW) Forscher*innen stehen vor der Herausforderung, qualitative Forschung in medizinischen Fachzeitschriften zu veröffentlichen. Dabei ist das deskriptive, erklärende, erfahrungsbasierte und interpretierende Wissen, das durch qualitative Forschung gewonnen wird, für die Verbesserung der Gesundheitsversorgung unerlässlich. Anhand von drei Beispielen von Studien, die in medizinischen und SGW-Fachzeitschriften veröffentlicht wurden, erörtern wir Elemente, die SGW-Forscher*innen bei der Präsentation ihrer Forschung berücksichtigen können, um ihr Zielpublikum besser zu erreichen. Wir schlagen vor, dass SGW-Forscher*innen die grundlegenden Elemente ihrer Disziplin nicht aufgeben (d.h. erkenntnistheoretisches Paradigma, Forschungsziele, Studiendesign, Forschungsmethoden, Vertrauenswürdigkeit), während sie gleichzeitig die Vorlieben der Redakteur*innen und Gutachter*innen medizinischer Zeitschriften für Wissensformen berücksichtigen, die zu Veränderungen in der Praxis führen können. Je nachdem, was die Autor*innen ihrem Publikum vermitteln wollen, können andere Aspekte der Präsentation angepasst werden, um für die Leser*innenschaft leichter verständlich zu sein (z.B. Struktur, Schreibstil, Vokabular, zusammenfassende Tabellen, Interpretationsebene). Wir bleiben optimistisch, dass das medizinische Publikum, wenn wir es weiterhin mit qualitativ hochwertiger SGW-Forschung konfrontieren, lernen wird, verschiedene Standards für die Forschung zu akzeptieren und zusätzliche Präsentationsformen zu schätzen., Social science and humanities (SSH) researchers face challenges publishing qualitative research in medical journals. Yet, the descriptive, explanatory, experiential and interpretive knowledge generated by qualitative research is integral to the enhancement of health service delivery. Drawing on three examples of studies published in medical and SSH journals, we discuss elements SSH researchers can consider in the presentation of their research to better reach their intended audience. We suggest that SSH researchers resist abandoning the foundational elements of their discipline (i.e., epistemological paradigm, research objectives, study design, research methods, trustworthiness) while being mindful of medical journal editors' and reviewers' preference for practical knowledge that can inform practice change. Depending on what the authors hope to convey to their audience, other aspects pertaining to its presentation may be adapted to be more readily understood by the readership (i.e., structure, writing style, vocabulary, summary tables, interpretation level). We remain optimistic that if we continue to expose medical audiences to high-quality SSH research, they will learn to embrace diverse standards for research and value its other modes of presentation.

Additional file 1. Evaluation of democratic deliberation session. An English language copy of the post-deliberation questionnaire adapted from De Vries and colleagues (2011) is provided in Additional File 1.

Laser technology has steadily evolved over the last 50 years since its invention, and has generated a series of ramifications in experimental science. Particularly, lasers have enabled the creation of the shortest man-made event: a femtosecond pulse of electromagnetic radiation. Due to their unmatched spatial and temporal resolutions, femtosecond pulses have been used in a number of techniques to measure properties of individual molecules. One of these techniques is Coulomb Explosion Imaging (CEI), whose purpose is to retrieve the structure of individual molecules. Unlike frequency domain spectroscopy (which is ill-suited to characterize the structure of large molecules due to their complex spectra) and diffraction techniques (which only work if molecules can be locked into a crystallization pattern), CEI provides a direct measurement of the properties of individual molecules, instead of measuring a sample as a whole. This novel technique was first introduced to study molecular structure by colliding a beam of highly energetic ions onto a thin foil. The version of CEI used in this work uses a beam of neutral molecules and replaces the thin foil with femtosecond optical pulses. The introduction of the laser has brought with it the ability to conduct time-resolved measurements of molecular processes (breaking of molecular bonds, internuclear motion, for example) on a femtosecond time scale using pump-probe techniques in conjunction with CEI. Furthermore, CEI is presently the only technique that can discriminate single molecules based on their handedness. I have conducted a Laser Coulomb Explosion Imaging (LCEI) experiment using dicloromethane as a model polyatomic molecule. In order to perform LCEI, an intense femtosecond laser pulse is used to strip away electrons from a molecule and cause it to explode into smaller fragments. Imaging the molecule is done using data collected from its fragments. Thus, in practice LCEI can be seen as a technique comprising an experimental phase (Coulomb explosion) and an analytical phase (imaging). Dichloromethane was chosen for this study to prepare the techniques that are necessary for future experiments on chiral molecules. The experimental setup used for this instance of LCEI is the PATRICK instrument, a combination of high-end vacuum, electronics and laser equipment, which will also be described herein. The rest of this thesis will focus on the results obtained from the computational tools I developed for imaging the CEI data and obtaining physical properties about the exploded molecules. In doing so I have also obtained the first geometrical reconstructions of five atom molecules from CEI data, which will also be given in this study. Though LCEI is a general technique that can be exploited in a variety of different experiments, this particular project was built around the interest of imaging chiral molecules. Unlike mass, multipole moments, polarizabilities and other "conventional" physical properties of molecules, chirality arises solely from spatial symmetry considerations, making it more elusive. For example, in order to experimentally determine the properties of a molecule in the traditional manner, one proceeds by inferring molecular characteristics from general spectroscopic data pertaining to a sample of molecules. In this manner, molecules are ascribed properties based on statistical measurements done on a population. Although statistical methods are also used to measure the handedness of a sample of molecules, it is understood that these measurements yield information only about the sample, but not the individual molecules themselves. Indeed, chirality is not a property of a type of molecule, but of individual molecules, rendering LCEI very suitable to measure chirality. Accordingly, it is the ultimate goal of this thesis to set the stage for future experiments involving the measurement of the handedness of individual chiral molecules.

Since the original prediction and demonstration of attosecond pulses, attosecond physics has entrenched itself in the ultrafast sciences, and promises to advance a wide range of scientific disciplines. It has the potential to provide key developments and insights in several research areas, such as atomic physics, quantum chemistry, biology and medicine. At present, engaging in this novel field of research is rather prohibitive, due to the high costs of cutting-edge technology and a steep learning curve. After all, playing with attosecond pulses is tantamount to playing with the shortest events ever made by man! Nonetheless, these are just typical growing pains of a new and exciting research area, and will eventually subside to make attosecond science accessible to a broad research community. In the meanwhile, as this promising field is taking its baby steps, it is the responsibility of those working at the cutting edge to propose novel experiments, and develop the tools and models that will be used in the future, as the field matures. Attosecond science comprises two frontiers: (i) the generation and characterization of increasingly intense, energetic, short and isolated attosecond pulses; and (ii) the design of experiments to probe physical systems on the attosecond time scale, the holy grail being the attosecond pump-attosecond probe time-resolved spectroscopic measurement. The second frontier offers a deeper understanding of the temporal behavior of the microcosm, but relies on advancements made in the first one. At present, both of these frontiers heavily rely on the attosecond streaking technique, which consists in energy-resolving photoelectrons ejected by an attosecond extreme ultraviolet pulse, in the presence of a phase-stabilized and temporally synchronized near-infrared field. Although it was originally devised as a means to characterize attosecond pulses, this measurement technique has even produced new discoveries in atomic and solid-state physics, due to pioneering experiments by M. Drescher, A. Cavalieri, G. Sansone, M. Schultze, and others, and has inspired novel theories of laser-dressed photoionization by V. S. Yakovlev, A. Scrinzi, O. Smirnova, M. Y. Ivanov and others. In the first part of this thesis, I focus on new methods I developed for the analysis of attosecond streaking measurements. One of these methods, based on a formalism I devised based on electron trajectories in a laser field, can directly recover the chirp of an attosecond pulse from a set of streaked photoelectron spectra. Next, I describe a robust optimization algorithm, based on a formalism due to M. Kitzler et al., that can completely recover the temporal profile of an attosecond pulse with an arbitrary shape. This optimization algorithm was used to characterize the field of 80 as pulses, the shortest on record, and to uncover a delay of 20 as between the photoemissions from the 2s and 2p sub-shells of neon; both experiments were performed here at the Max Planck Institut fuer Quantenoptik in 2008 and 2010, respectively. Moreover, during the course of this work, it was established by V. S. Yakovlev et al. that the attosecond streaking technique generally measures a quantity that is related to the photoelectron wave packet, not the attosecond light pulse. Only when the energy-resolved dipole response, given by the bound-free transition matrix elements, is nearly constant can we take the electron wave packet as a replica of the attosecond pulse. In light of this finding, I show that the attosecond streaking technique provides a means to measure and even time-resolve the energy-dependent phase of transition dipole matrix elements. Finally, I consider the laser-dressed scattering of an attosecond photoelectron wave packet. I show that the scattering of a photoelectron, emitted by an attosecond pulse from a localized state in a spatially extended system, can be influenced by a near-infrared laser field. Measuring the photoelectron spectrum reveals an interference pattern which is affected by the intensity of the near-infrared field. To describe these effects, I introduce a model based on classical trajectories that quantitatively predicts laser-dressed photoelectron spectra for such a spatially-extended system.