Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

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From Body to Backend: Mobile and wireless data recording and transmission in the area of healthcare, emergency, and AAL

In vielen Szenarien in den Bereichen Gesundheitspflege, Notfallversorgung und AAL werden Daten durch Sensoren am menschlichen Körper erhoben. Diese Daten werden je nach Anwendungsfall entweder zur späteren Auswertung lokal gespeichert oder aber direkt über eine Funkverbindung zu einer Datensenke gesendet. In dieser Arbeit wird ein System vorgestellt, das in der Lage ist, Szenarien mit unterschiedlichen Anforderungen zu ermöglichen, wobei die gesamte Übertragungsstrecke vom Körper über häusliche Gateways bis hin zu Servern bzw. Backendsystemen abgedeckt wird. Da kein geeignetes Hardwaresystem verfügbar war, wurde mit INGA ein Sensorknoten geschaffen, der den Anforderungen an die Sensorausstattung, die Verarbeitungskapazität und die Funkübertragung gerecht wird. Zur Absicherung der Funkübertragung werden die Daten mit einem auf One-Time-Pads basierenden Kryptosystem verschlüsselt. Die Übertragung zum häuslichen Gateway geschieht über ein unterbrechungstolerantes Kommunikationsprotokoll (DTN), welches auch eine implizite Synchronisation derjenigen Daten ermöglicht, die außerhalb der Kommunikationsreichweite des Gateways, also außerhalb der Wohnung, aufgenommen wurden. Um im außerhäuslichen Bereich auch Notfallmeldungen absetzen zu können, wird außerdem ein mobiler Notfallkanal über ein Smartphone realisiert. Die aufgezeichneten Daten werden in den betrachteten Szenarien auf dem Gateway in der Wohnung der betreffenden Person gespeichert und dort ausgewertet. Um außerdem auch die Integrität dieser verteilen Gateways auch bei einer größeren Anzahl von Installationen sicherstellen zu können, wird ein System zur Fernüberwachung der verteilten Gateways über selbstinitiierte VPN-Verbindungen zu einer zentralen Überwachungsinstanz geschaffen. Mit den vorgestellten Lösungen werden somit vielfältige Anwendungsfälle mit teils gegensätzlichen Anforderungen unterstützt, die noch dazu parallel auf ein und denselben Sensorsystemen und mit den gleichen Protokollen betrieben werden können.In the area of healthcare, emergency response and AAL, data are gathered by different sensors attached to the human body. Depending on the specific use case, these data are either stored locally for an offline analysis or transmitted directly via a radio link to a sink to enable an online assessment. In this thesis, a system that supports scenarios with different requirements is presented whereas the whole communication chain from the human body via home gateways to distant backend systems is addressed. Transferring sensor data from the worn sensor systems to a home gateway in a secure, safe, and lossless way is one of the major challenges. As no existing sensor system fulfilled the requirements completely, a new wireless sensor node has been developed: INGA. On the one hand, this node is equipped with the required set of sensors for movement and activity detection. On the other hand, the computation and communications capabilities are suitable for the addressed use cases. The wireless channel is secured by a cryptosystem relying on One Time Pads. Data are transferred to the gateway by a disruption tolerant network protocol (DTN) which also allows an implicit synchronization of data recorded outside the communication range of the gateway. To additionally enable a personal emergency response system outside of the habitation, a smartphone is utilized for mobile alarm messages. In the addressed scenarios, data are stored and processed on the home gateway in the residence of the user. In case of a detected emergency these gateways may trigger alarm messages. To ensure the integrity and functionality of the distributed gateways, a remote instance monitors these systems. The presented solutions support multiple use cases with competing aims which are now able to run simultaneously on the same sensor systems and using the same protocols

Exponentially Reduced Reflection (ERR) versusLinear Wave Theory (Airy/Laplace)

The linear wave theory according to Airy/Laplace (1842) is widely used by engineers however violates the law of conservation of mass and considers local ground inclination α = 0⁰ only. Both shortcomings can be avoided (a) by extending Schulejkin's mirror method to represent orbital kinematics over flat ground to inclinations 0⁰ ≤ α ≤ 90⁰ and (b) by referring to the phase shift Δϕ between incident and reflected waves according to the author´s definition of the complex reflection coefficient CRC. This contribution includes Exponentially Reduced Reflection (ERR) for the first time as a wave theory applicable to complex boundary conditions, considering a priori an important cause of wave deformation over inclined seafloor. For instance, the change of the total orbital kinematics (orbital paths, velocities and accelerations) related to the water surface is shown for decreasing water depths on a slope 1 : n = 1 : 2. In contrast to the Airy/Laplace theory, lower orbital velocities are obtained above the still water level, which is important with respect to the design of offshore structures

Governing digital crisis responses: platform standards and the dilemma of COVID-19 contact tracing

In response to the impact of the SARS-CoV-2 (COVID-19) pandemic, various developers turned to smartphone-based contact tracing to address the challenges of manual tracing. Due to the presence of network effects, i.e., the effectiveness of contact tracing applications increases with the number of users, information technology standards were critical to the technology’s success. The standardization efforts in Europe led to a variety of trade-offs concerning the choice of an appropriate technological architecture due to the contradictory tensions resulting from the dualism between the need for contact tracing data to contain the pandemic and the need for data minimization to preserve user privacy. Drawing predominantly on the software platform and standards literature, we conduct an interpretive case study to examine the emergence and consequences of this multi-layered decision situation. Our findings reveal how Google and Apple were able to limit the individual leeway of external developers, thereby effectively resolving the European standards war. Furthermore, we identify and discuss the various short-term and long-term trade-offs associated with the standardization of contact tracing applications and translate our findings into recommendations for policy makers with respect to future crisis situations. Specifically, we propose a strategy grounded in our data that enables responsible actors to make goal-oriented and rapid decisions under time constraints