Cavity QED of Strongly Correlated Electron Systems: A No-go Theorem for Photon Condensation

In spite of decades of work it has remained unclear whether or not superradiant quantum phases, referred to here as photon condensates, can occur in equilibrium. In this Letter, we first show that when a non-relativistic quantum many-body system is coupled to a cavity field, gauge invariance forbids photon condensation. We then present a microscopic theory of the cavity quantum electrodynamics of an extended Falicov-Kimball model, showing that, in agreement with the general theorem, its insulating ferroelectric and exciton condensate phases are not altered by the cavity and do not support photon condensation.Comment: Reference list updated and minor typos correcte

Designing for Exploratory Search on Touch Devices

Exploratory search confront users with challenges in expressing search intents as the current search interfaces require investigating result listings to identify search directions, iterative typing, and reformulating queries. We present the design of Exploration Wall, a touch-based search user interface that allows incremental exploration and sense-making of large information spaces by combining entity search, flexible use of result entities as query parameters, and spatial configuration of search streams that are visualized for interaction. Entities can be flexibly reused to modify and create new search streams, and manipulated to inspect their relationships with other entities. Data comprising of task-based experiments comparing Exploration Wall with conventional search user interface indicate that Exploration Wall achieves significantly improved recall for exploratory search tasks while preserving precision. Subjective feedback supports our design choices and indicates improved user satisfaction and engagement. Our findings can help to design user interfaces that can effectively support exploratory search on touch devices

An uncommon presentation of eosinophilic granulomatosis with polyangiitis: a case report

INTRODUCTION: Eosinophilic granulomatosis with polyangiitis is a rare and potentially fatal disease if not readily diagnosed. Cerebral involvement is extremely rare and clinical presentation as hemorrhagic stroke is even rarer. CASE PRESENTATION: A 58-year-old Caucasian man was admitted to our medical unit because of a computed tomography-diagnosed hemorrhagic stroke with right-sided hemiparesis and fever. A chest computed tomography scan also revealed multiple bilateral pulmonary infiltrates; coronary artery, and carotid and left vertebral artery calcifications were also observed. Empiric antimicrobial therapy with cephalosporins was promptly undertaken; low-molecular-weight heparin was introduced as prophylaxis for venous thromboembolism. Over the following days, magnetic resonance imaging scans showed a regression of the hemorrhagic framework, also revealing hypoxic areas consistent with acute ischemic lesions. With a computed tomography scan showing a worsening of his pulmonary framework, antimicrobial therapy was modified and corticosteroids were introduced. A new blood cell count revealed further increased leukocytosis (17.49×10(3)μL), characterized by a surprising rise of eosinophilic cells (32.8%). Angiography of the coronary arteries found diffuse dilatations with severe signs of endothelial damage. Such an unexpected framework induced a strong suspicion that the stroke was the expression of a systemic vasculitis, which had triggered his cerebral, coronary, and pulmonary frameworks. The search for antineutrophil cytoplasmic antibody was positive for perinuclear antineutrophil cytoplasmic antibody, and eosinophilic granulomatosis with polyangiitis was diagnosed. Explaining to the patient the rarity of his disease, and what the most typical presentations of eosinophilic granulomatosis with polyangiitis were, he revealed that before admission he had had scalp injuries, in the nuchal region, and had taken corticosteroids as self-medication, with subsequent disappearance of the lesions. Therefore, high-dose corticosteroid treatment was started, and at discharge he was in good clinical condition with a slight right-sided hyposthenia. CONCLUSIONS: A diagnosis of eosinophilic granulomatosis with polyangiitis is often difficult, but we are convinced that intake of corticosteroids on a self-prescribed basis may have obscured the clinical presentation. Therefore, this case also suggests how the growing phenomenon of self-medication can be harmful, and that a careful investigation of clinical history is still an act of paramount importance

A wearable multimodal interface for exploring urban points of interest

Locating points of interest (POIs) in cities is typically facilitated by visual aids such as paper maps, brochures, and mobile applications. However, these techniques require visual attention, which ideally should be on the surroundings. Non-visual techniques for navigating towards specific POIs typically lack support for free exploration of the city or more detailed guidance. To overcome these issues, we propose a multimodal, wearable system for alerting the user of nearby recommended POIs. The system, built around a tactile glove, provides audio-tactile cues when a new POI is in the vicinity, and more detailed information and guidance if the user expresses interest in this POI. We evaluated the system in a field study, comparing it to a visual baseline application. The encouraging results show that the glovebased system helps keep the attention on the surroundings and that its performance is on the same level as that of the baseline

Theory of Photon Condensation in a Spatially-Varying Electromagnetic Field

The realization of equilibrium superradiant quantum phases (photon condensates) in a spatially-uniform quantum cavity field is forbidden by a "no-go" theorem stemming from gauge invariance. We here show that the no-go theorem does not apply to spatially-varying quantum cavity fields. We find a criterion for its occurrence that depends solely on the static, non-local orbital magnetic susceptibility $\chi_{\rm orb}(q)$, of the electronic system (ES) evaluated at a cavity photon momentum $\hbar q$. Only 3DESs satisfying the Condon inequality $\chi_{\rm orb}(q)>1/(4\pi)$ can harbor photon condensation. For the experimentally relevant case of two-dimensional (2D) ESs embedded in quasi-2D cavities the criterion again involves $\chi_{\rm orb}(q)$ but also the vertical size of the cavity. We use these considerations to identify electronic properties that are ideal for photon condensation. Our theory is non-perturbative in the strength of electron-electron interaction and therefore applicable to strongly correlated ESs.Comment: 25 page

A two-step, user-centered approach to personalized tourist recommendations

Geo-localized, mobile applications can simplify a tourist visit, making the relevant Point of Interests more easily and promptly discernible to users. At the same time, such solutions must avoid creating unfitting or rigid user profiles that impoverish the users' options instead of refining them. Currently, user profiles in recommender systems rely on dimensions whose relevance to the user is more often presumed than empirically defined. To avoid this drawback, we build our recommendation system in a two-step process, where profile parameters are evaluated preliminarily and separately from the recommendations themselves. We describe this two-step evaluation process including an initial survey (N=206), and a subsequent controlled study (N=24). We conclude by emphasizing the benefit and generalizability of the approach

QRouteMe: A Multichannel Information System to Ensure Rich User-Experience in Exhibits and Museums

In this article the QRouteMe system is presented. QRouteMe is a multichannel information system built to ensure rich user experiences in exhibits and museums. The system starts from basic information about a particular exhibit or museum while delivering a wide user experience based on different distribution channels. The organization of the systems’ components allow to build different solutions that can be simultaneously delivered on different media. A wide range of media from touch-screen installations to portable devices like smartphones have been used. The used devices can communicate each others to increase the usability and the user experience for the visitors. Another important feature of the system is the definition of an inexpensive auto-localization system based on fiduciary marks distributed all around the building. In this article the system is presented from an architectural and functional point of view. A case study and analysis of experimental results are also provided in a real environment where the system was deployed

Designing for Mixed Reality Urban Exploration

This paper introduces a design framework for mixed reality urban exploration (MRUE), based on a concrete implementation in a historical city. The framework integrates different modalities, such as virtual reality (VR), augmented reality (AR), and haptics-audio interfaces, as well as advanced features such as personalized recommendations, social exploration, and itinerary management. It permits to address a number of concerns regarding information overload, safety, and quality of the experience, which are not sufficiently tackled in traditional non-integrated approaches. This study presents an integrated mobile platform built on top of this framework and reflects on the lessons learned

Intentstreams: Smart parallel search streams for branching exploratory search

The user's understanding of information needs and the information available in the data collection can evolve during an exploratory search session. Search systems tailored for well-defined narrow search tasks may be suboptimal for exploratory search where the user can sequentially refine the expressions of her information needs and explore alternative search directions. A major challenge for exploratory search systems design is how to support such behavior and expose the user to relevant yet novel information that can be difficult to discover by using conventional query formulation techniques. We introduce IntentStreams, a system for exploratory search that provides interactive query refinement mechanisms and parallel visualization of search streams. The system models each search stream via an intent model allowing rapid user feedback. The user interface allows swift initiation of alternative and parallel search streams by direct manipulation that does not require typing. A study with 13 participants shows that IntentStreams provides better support for branching behavior compared to a conventional search system