Observation of a stronger-than-adiabatic change of light trapped in an ultrafast switched GaAs-AlAs microcavity

We study the time-resolved reflectivity spectrum of a switched planar GaAs-AlAs microcavity. Between 5 and 40 ps after the switching (pump) pulse we observe a strong excess probe reflectivity and a change of the frequency of light trapped in the cavity up to 5 linewidths away from the cavity resonance. This frequency change does not adiabatically follow the fast-changing cavity resonance. The frequency change is attributed to an accumulated phase change due to the time-dependent refractive index. An analytical model predicts dynamics in qualitative agreement with the experiments, and points to crucial parameters that control future applications.Comment: Discussed effect of probe bandwidth. Included functional forms of n(z) and R(z

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Applications of Eikonals in Optical Design

The polynomial fit eikonal can characterize any complex surface by converting a ray trace of the system into a phase space transformation. This phase space transformation provides the information required to define the radiance throughout the system. The characterization of the radiance throughout the system means that the eikonal can be used in lieu of a conventional ray trace. The initial computation time needed to create the polynomial fit eikonal of a surface can be high and the eikonal representation is not as accurate as a real ray trace of a system. However, in contrast to real ray traces, the polynomial fit eikonal provides more flexibility. For example, if a full optical system has each of its surfaces converted into eikonals, then any polynomial fit eikonal surface can be exchanged with any other polynomial fit eikonal surface without needing to run cumbersome ray traces. Furthermore, once the surface is fully characterized, the eikonal does not need to be recreated as the system changes. Computation time is thus faster overall for eikonal surfaces than for real ray traces. The eikonal becomes more accurate as more terms are included. This increase in accuracy is due to higher order terms of the eikonal fitting higher order optical aberrations. This dissertation explores how various optical factors, such as curvature and refractive index, affect the accuracy of the eikonal fit. Whenever an eikonal fit is performed, it is not guaranteed to be accurate enough for the application at hand, so error reduction is an important factor when building eikonal surfaces. As the system’s étendue increases, it becomes harder to fit the system to a single eikonal with reasonable error. In this case, it can be advantageous to split the system’s étendue into smaller, more manageable sections to reduce the error of the eikonal. For systems with complex sources, the source can be compiled into a probability density function. This probability density function allows for the characterization of a source into a continuous function using a ray set as the basis. Rays can then be interpolated by a random weighted drawing of new rays from the probability density function and then propagated through the optical system using the eikonal

Analyse von Strukturen im Luftraum mit Clusterverfahren

Am Deutschen Zentrum für Luft und Raumfahrt werden Konzepte untersucht, die möglichst effiziente Flugverbindungen ermöglichen. Dabei ist das Clustern von Flugrouten relevant, um generelle Strukturen identifizieren zu können. Die Eignung verschiedener Clusterverfahren wird in dieser Bachelorarbeit untersucht. Das Clusterverfahren HDBSCAN ist von besonderem Interesse, da es Dichteabhängigkeit und Hierarchien kombiniert. Dazu wird eine Java-Bibliothek für Clusteranwendungen entwickelt. Diese umfasst ein allgemeines Framework, den HDBSCAN als Verfahren und einen erweiterbaren Auswertungsmechanismus mit dem Dunn-Index. Die Bibliothek wird in den Routengenerator (RouGe) integriert. Mit dieser DLR Eigenentwicklung lassen sich Flugdaten analysieren und Clusteranalysen mit dem Fuzzy-c-Means (FCM) Algorithmus durchführen. Es wird anhand der Flugdaten vom 06. Juni 2020 eine Clusteranalyse für den oberen deutschen Luftraum mit beiden Verfahren durchgeführt. Es stellt sich heraus, dass die grundsätzliche Lage der Clusterzentren ähnlich ist. Allerdings werden vom HDBSCAN viele Wegpunkte als Rauschen identifiziert. Dies ist mit dem FCM nicht möglich. Weiterhin wird die Routenglättung als Möglichkeit zur Rechenzeitminimierung des HDBSCAN untersucht. Dabei werden aus den Flugtrajektorien Wegpunkte entfernt, die keinen großen Einfluss auf den ursprünglichen Routenverlauf haben. Dadurch können die Datenpunkte für das untersuchte Szenario um etwa 29% reduziert werden. Dies führt zu einer Reduktion der Cluster um etwa 26%, was allerdings die grundsätzliche Clusterverteilung nur minimal beeinflusst. Die Rechenzeit kann dadurch deutlich reduziert werden. Der HDBSCAN erweist sich als geeignet für die Analyse von Lufträumen und kann im Rahmen weiterer Untersuchungen eingesetzt werden

Tracking train passengers using accelerometer data from their smartphones without the use of training data

Today's smartphones are equipped with sensors, some of which can be accessed by any application at runtime without the user's permission. Attackers can exploit this to track the user's train journeys and create movement profiles. In this thesis, a framework is developed to enable the detection of train journey paths using sensor data from the victim's smartphone. Special focus is put on the accelerometer data, as it is the most suitable for this task. Training data for each train route to be recognized is not needed, unlike machine learning approaches. The detection works solely on the basis of freely available data, map data from OpenStreetMap and timetable data. From these, a graph is generated that represents the rail and train line network. This is possible for an arbitrary area. Train related data is extracted from the sensor data and matched with the graph. In the proposed framework, paths are searched based on the travel time and the start and end time. For the found paths, further features are matched with the sensor data. These are based on stop detection, driving directions and timetable data. Each path is given a score, which indicates how likely it is that the path was actually driven. It is also possible to consider journeys consisting of consecutive sections between which there can be any changeover times. In the evaluation it could be shown that the correct path always belongs at least to the 16% of paths with the highest scores. In the final test case, the actual path was even the one with the highest score. It was also found that the correct functionality of the stop detection and the presence of train delay data can greatly improve the results

Simulation Exercises for robust Flight dispatching solution under thunderstorm disruptions

The development, implementation and validation of optimisation algorithms for robust airline operations that result in stable and resilient Air Traffic Management (ATM) performance even in disturbed scenarios are the overall goals of START. This presentation focusses on the validation part. The validation of the START robust airline operations is performed by comparing the performance of a reference and a resilient scenario under disturbed and undisturbed conditions. The reference scenario is derived from the traffic demand for two days in 2018, June 7th and June 10th with strong convective weather phenomena. The resilient scenario is built on the reference scenario but is prepared for more frequent planning updates due to changing forecasts of capacity shortfalls mainly caused by weather impacts. Resiliency refers to the intrinsic ability of a system to adjust its functioning prior to, during, or following changes and disturbances. Within the validation trials performed, disturbances are included by means of convective weather areas which are handled as No-Fly-Zones (NFZ). Validation of the START results is performed threefold. First, reference and resilient scenarios are compared, mainly focussing on expected duration of overall conflict hours of aircraft with other aircraft and convective weather zones. Second, real life departure uncertainties are added by means of Monte-Carlo simulations with different distributions. Finally, scenarios are resolved with conflict resolution algorithms above FL150 as far as possible. The presentation gives an overview of the validation results, showing an overall low but stable benefit for the adapted aircraft fleet (Star Alliance) of the resilient scenario, with no negative effects for the global scenario

Enhancing prime editor activity by directed protein evolution in yeast

Prime editing is a highly versatile genome editing technology that enables the introduction of base substitutions, insertions, and deletions. However, compared to traditional Cas9 nucleases prime editors (PEs) are less active. In this study we use OrthoRep, a yeast-based platform for directed protein evolution, to enhance the editing efficiency of PEs. After several rounds of evolution with increased selection pressure, we identify multiple mutations that have a positive effect on PE activity in yeast cells and in biochemical assays. Combining the two most effective mutations – the A259D amino acid substitution in nCas9 and the K445T substitution in M-MLV RT – results in the variant PE_Y18. Delivery of PE_Y18, encoded on DNA, mRNA or as a ribonucleoprotein complex into mammalian cell lines increases editing rates up to 3.5-fold compared to PEmax. In addition, PE_Y18 supports higher prime editing rates when delivered in vivo into the liver or brain. Our study demonstrates proof-of-concept for the application of OrthoRep to optimize genome editing tools in eukaryotic cells.ISSN:2041-172

Enhancing prime editor activity by directed protein evolution in yeast

Abstract Prime editing is a highly versatile genome editing technology that enables the introduction of base substitutions, insertions, and deletions. However, compared to traditional Cas9 nucleases prime editors (PEs) are less active. In this study we use OrthoRep, a yeast-based platform for directed protein evolution, to enhance the editing efficiency of PEs. After several rounds of evolution with increased selection pressure, we identify multiple mutations that have a positive effect on PE activity in yeast cells and in biochemical assays. Combining the two most effective mutations – the A259D amino acid substitution in nCas9 and the K445T substitution in M-MLV RT – results in the variant PE_Y18. Delivery of PE_Y18, encoded on DNA, mRNA or as a ribonucleoprotein complex into mammalian cell lines increases editing rates up to 3.5-fold compared to PEmax. In addition, PE_Y18 supports higher prime editing rates when delivered in vivo into the liver or brain. Our study demonstrates proof-of-concept for the application of OrthoRep to optimize genome editing tools in eukaryotic cells