A gravity derivation of the Tisza-Landau Model in AdS/CFT

We derive the fully backreacted bulk solution dual to a boundary superfluid with finite supercurrent density in AdS/CFT. The non-linear boundary hydrodynamical description of this solution is shown to be governed by a relativistic version of the Tisza-Landau two-fluid model to non-dissipative order. As previously noted, the phase transition can be both first order and second order, but in the strongly-backreacted regime at low charge q we find that the transition remains second order for all allowed fractions of superfluid density.Comment: 27 pages, 6 figures, 1 appendix; version published in PR

Linear gravity from conformal symmetry

We perform a unified systematic analysis of $d+1$ dimensional, spin $\ell$ representations of the isometry algebra of the maximally symmetric spacetimes AdS$_{d+1}$, $\mathbb{R}_{1,d}$ and dS$_{d+1}$. This allows us to explicitly construct the effective low-energy bulk equations of motion obeyed by linear fields, as the eigenvalue equation for the quadratic Casimir differential operator. We show that the bulk description of a conformal family is given by the Fierz-Pauli system of equations. For $\ell = 2$ this is a massive gravity theory, while for $\ell = 2$ conserved currents we obtain Einstein gravity and covariant gauge fixing conditions. This analysis provides a direct algebraic derivation of the familiar AdS holographic dictionary at low energies, with analogous results for Minkowski and de Sitter spacetimes.Comment: 21 pages, 1 figur

Uncovering the Moral Heuristics of Altruism: A Philosophical Scale

Extant research suggests that individuals employ traditional moral heuristics to support their observed altruistic behavior; yet findings have largely been limited to inductive extrapolation and rely on relatively few traditional frames in so doing, namely, deontology in organizational behavior and virtue theory in law and economics. Given that these and competing moral frames such as utilitarianism can manifest as identical behavior, we develop a moral framing instrument—the Philosophical Moral-Framing Measure (PMFM)—to expand and distinguish traditional frames associated and disassociated with observed altruistic behavior. The validation of our instrument based on 1015 subjects in 3 separate real stakes scenarios indicates that heuristic forms of deontology, virtue-theory, and utilitarianism are strongly related to such behavior, and that egoism is an inhibitor. It also suggests that deontic and virtue-theoretical frames may be commonly perceived as intertwined and opens the door for new research on self-abnegation, namely, a perceived moral obligation toward suffering and self-denial. These findings hold the potential to inform ongoing conversations regarding organizational citizenship and moral crowding out, namely, how financial incentives can undermine altruistic behavior

Quantitative analysis of in situ time-resolved RHEED during growth of self-catalysed GaAs nanowires

Die morphologischen und kristallographischen Eigenschaften vertikaler, freistehender Nanodrähte, welche mittels der Dampf-Flüssigkeits-Feststoff-Methode (VLS) gezüchtet werden, sind durch ein kompliziertes Wechselspiel der Wachstumsparameter während des Herstellungsprozesses beeinflusst. Das Verständnis und die Kontrolle dieser dynamischen Prozesse sind folglich Voraussetzung für die Herstellung von Nanodrähten mit maßgeschneiderten Eigenschaften. Zeitaufgelöste $\textit{in situ}$ Charakterisierungsmethoden ermöglichen die direkte Beobachtung und Analyse solcher dynamischen Prozesse, sowie deren Wechselwirkung. Die $\textit{in situ}$ Beugung hochenergetischer Elektronen unter streifendem Einfall (RHEED) spielt in der gegenwärtigen Nanodrahtforschung unter den kristallographischen $\textit{in situ}$ Charakterisierungsmethoden, aufgrund der bisherigen Beschränkung auf rein $\textit{qualitative}$ Analysen, eine untergeordnete Rolle, obwohl eine umfassende Verfügbarkeit der Methode an fast allen Molekularstrahlepitaxie-Anlagen besteht. In der vorliegenden Arbeit wird ein Ansatz zur $\textit{quantitativen}$ Auswertung von zeitaufgelösten Intensitätsverläufen der $\textit{in situ}$ gemessenen RHEED Beugungsbildern entwickelt, welche während des Wachstums von vertikaler, freistehender Nanodrähte in Transmissionsgeometrie gemessen werden. Auf dieser Basis werden methodische Einschränkungen der $\textit{qualitativen}$ Analyse überwunden. Über die Intensitätsverläufe charakteristischer Beugungsreflexe der verschiedenen Kristallphasen erlaubt RHEED die $\textit{quantitative}$ Untersuchung von in III-V Nanodrähten auftretenden strukturellen Polytypismus. In der Arbeit wird dazu ein Simulationsprogramm entwickelt, welches sowohl die Wechselwirkungen der Elektronen mit einzelnen Nanodrähten als auch den Einfluss des gesamten Nanodrahtensembles auf die gebeugten Intensitäten abschätzt, sowie deren Dynamik während der Nanodrahtherstellung berücksichtigt. Mittels Simulationen werden Einflüsse morphologischer und kristallographischer Veränderungen während des Wachstums auf die resultierenden Intensitätsverläufe der Beugungsreflexe untersucht und deren Ursache diskutiert. Die wichtigsten Herausforderungen, Möglichkeiten und Einschränkungen der Methode für $\textit{in situ}$ RHEED Studien des Nanodrahtwachstums werden dabei identifiziert. Darüber hinaus wird gezeigt, dass die bei RHEED an Nanodrähten durch Elektronenabsorption verursachte Elektronenschattenbildung, zu einem auf die Nanodrahtspitze reduzierten Informationsvolumen führt, was RHEED unempfindlich für die untere, abgeschattete Nanodrahtregion macht. Die erhöhte höhenselektive Sensitivität von $\textit{in situ}$ RHEED gegenüber der Nanodrahtspitze eignet sich insbesondere dazu, komplementäre Informationen zu den etablierten $\textit{in situ}$ Charakterisierungsmethoden, wie $\textit{in situ}$ Röntgenbeugung (XRD), zu erhalten. Simultan durchgeführte $\textit{in situ}$ RHEED und $\textit{in situ}$ XRD Experimente während der Herstellung von selbstkatalysierten GaAs Nanodrähten erlaubten es, diese Komplementarität auszunutzen. Während $\textit{in situ}$ RHEED vorrangig Informationen über die Kristallstruktur an der Nanodrahtspitze liefert, untersucht $\textit{in situ}$ XRD das gesamte Nanodrahtvolumen. Zusammen mit abschließender $\textit{ex situ}$ Rasterelektronenmikroskopie (REM), erhält man umfassende und repräsentative Informationen über die morphologische und kristallographische Entwicklung großer Nanodrahtensembles während des Wachstums. Darüber hinaus wird $\textit{in situ}$ RHEED als laborbasierte, eigenständige Methode etabliert. Es wird gezeigt, dass $\textit{in situ}$ RHEED untersetzt mit angemessenem $\textit{a priori}$ Wissen, eine leistungsfähige Charakterisierungstechnik der Nanodraht-Kristallstruktur ist und sich daher auch für grundlegende Nanodraht-Wachstumsstudien mit gängigen Molekularstrahlepitaxie-Anlagen eignet. Mit Hilfe der hier vorgestellten Datenanalyseprozeduren konnte allein mittels laborbasierter $\textit{in situ}$ RHEED- und REM-Analytik ein kürzlich publiziertes theoretisches VLS-Wachstumsmodell an großen Nanodrahtensembles $\textit{quantitativ}$ verifiziert werden. Zusammenfassend ebnen die in dieser Arbeit vorgestellten Ergebnisse den Weg für die Verwendung von $\textit{quantitativem}$ $\textit{in situ}$ RHEED während des Nanodrahtwachstums, sowohl als eigenständige, laborbasierte, wie auch als komplementär zu anderen Charakterisierungsmethoden einsetzbare $\textit{in situ}$ Analysemethode der Kristallstruktur

Anchoring The Cognitive Map To The Visual World

To interact rapidly and effectively with the environment, the mammalian brain needs a representation of the spatial layout of the external world (or a “cognitive map”). A person might need to know where she is standing to find her way home, for instance, or might need to know where she is looking to reach for her out-of-sight keys. For many behaviors, however, simply possessing a map is not enough; in order for a map to be useful in a dynamic world, it must be anchored to stable environmental cues. The goal of the present research is to address this spatial anchoring problem in two different domains: navigation and vision. In the first part of the thesis, which comprises Chapters 1-3, we examine how navigators use perceptual information to re-anchor their cognitive map after becoming lost, a process known as spatial reorientation. Using a novel behavioral paradigm with rodents, in Chapter 2 we show that the cognitive map is reoriented by dissociable inputs for identifying where one is and recovering which way one is facing. The findings presented in Chapter 2 also highlight the importance of environmental boundaries, such as the walls of a room, for anchoring the cognitive map. We thus predicted that there might exist a brain region that is selectively involved in boundary perception during navigation. Accordingly, in Chapter 3, we combine transcranial magnetic stimulation and virtual-reality navigation to reveal the existence of such a boundary perception region in humans. In the second part of this thesis, Chapter 4, we explore whether the same mechanisms that support the cognitive map of navigational space also mediate a map of visual space (i.e., where one is looking). Using functional magnetic resonance imaging and eye tracking, we show that human entorhinal cortex supports a map-like representation of visual space that obeys the same principles of boundary-anchoring previously observed in rodent maps of navigational space. Together, this research elucidates how mental maps are anchored to the world, thus allowing the mammalian brain to form durable spatial representations across body and eye movements

Re-Think Insurance: A New Perspective of InsurTech

Technology improves performances of industries generally. While some applications impact insurance industry profoundly, however, some of the improvement is more of office automation and is better not classified as InsurTech. The article is to provide a practical perspective of InsurTech from the review of definitions and purposes of insurance, and the induction of risk information and risk financing, to silhouette insurance ecosystem and framework of InsurTech. Under risk information, the information layering is explored and the basic three elements of risk, contract and portfolio are identified in insurance ecosystem; under risk financing, transaction costs of insurance and law of large numbers are applied. Then, we propose a framework based on the three elements for InsurTech in regard of availability, affordability and assurability. Two approaches are also proposed for InsurTech development - evolutionary way to revise specific areas of the current insurance models and revolutionary way to revamp the insurance models as to redesign the arrangement of risk protection

Estimating Cost Savings of Coordinating Regional Non-Emergency Human Transport Services

Local public transportation agencies provide a nonemergency human transport service to nearby hospitals and doctors' offices. Some users require specialized medical services at a hospital located out of the normal service area. In the Piedmont/Triad region of North Carolina, the Piedmont Authority for Regional Transportation (PART) began PART Connections in April 2004, to provide two daily transportation services between the Piedmont/Triad area and the UNC/Duke medical areas. Using current operating cost data of participating transportation systems, round-trip costs to the UNC/Duke medical areas from each county and to the nearest PART Connections stop are estimated. Given the actual number of passengers served by PART Connections during the first nine-month period of the service, the net saving in the operating cost by participating PART Connections is estimated for each system. Then, the total service hours saved by using PART Connections are estimated for each system, and are used to estimate the number of additional passengers served within the system. It is estimated that PART Connections could provide a net saving of $38,000 on operation expenses annually to the participating four county transportation systems. More importantly, PART Connections would enable the four county systems to provide more than 10,000 additional passenger trips within each county annually, by using the saved resources. In addition, 12 local community transportation providers in 15 western counties of the Piedmont/Triad region, which currently do not participate in PART Connections, are estimated to save a modest$9,600 in total annually, by using PART Connections

The financial risks and barriers to electricity infrastructure in Kenya, Tanzania, and Mozambique: a critical review of the academic literature

The recent academic literature contains a number of hypotheses, drivers, or explanations to reveal why electricity infrastructure isn’t being developed within sub-Saharan Africa (SSA) in the 21st century. In this paper, we argue that this literature is misdirected, or at least incomplete, in how it approaches risk. We hypothesise that this lack of infrastructure development in the region reflects a dearth of investment due to the existence of excessive negative uncertainties or risks – as investment is a function of uncertainty and reward – but that the recent academic literature appears to not appreciate this. To make this argument, we chose a manageable sample of three African countries, which already had a notable body of academic literature concerning them: Kenya, Mozambique and Tanzania. Focusing on these countries, we then undertook a systematic review of 815 ‘peer reviewed’ papers published on the academic libraries of Scopus and/or the Web of Science on the topic of electricity, infrastructure, and risk over a five-year period to see how this literature evaluated the problem. Drawing from the most relevant 101 studies within that sample, we critically examine the methodological, conceptual, and empirical aspects of this literature