Quantum charge glasses of itinerant fermions with cavity-mediated long-range interactions

We study models of itinerant spinless fermions with random long-range interactions. We motivate such models from descriptions of fermionic atoms in multi-mode optical cavities. The solution of an infinite-range model yields a metallic phase which has glassy charge dynamics, and a localized glass phase with suppressed density of states at low energies. We compare these phases to the conventional disordered Fermi liquid, and the insulating electron glass of semiconductors. Prospects for the realization of such glassy phases in cold atom systems are discussed.Comment: 16 page

Asymmetric Surface Plasmon Polariton Emission by a Dipole Emitter Near a Metal Surface

We show that the surface plasmon polariton (SPP) radiation patterns of point-dipole emitters in the vicinity of a metal-dielectric interface are generally asymmetric with respect to the location of the emitter. In particular rotating dipoles, which emit elliptically polarized light, produce highly asymmetric SPP radiation fields that include unidirectional emission. Asymmetric SPP radiation patterns also result when a dipole oscillates tilted with respect to the plane of the interface and optical losses or gains are present in the materials. These effects can be used to directionally control SPP emission and absorption, as well as to study emission and scattering processes close to metal-dielectric interfaces. Possible implementations of asymmetrically emitting SPP sources are discussed.Engineering and Applied Science

Migration and homeostasis of naive T cells depends on coronin 1-mediated prosurvival signals and not on coronin 1-dependent filamentous actin modulation

Coronins are WD repeat-containing proteins highly conserved in the eukaryotic kingdom implicated in the regulation of F-actin. Mammalian coronin 1, one of the most conserved isoforms expressed in leukocytes, regulates survival of T cells, which has been suggested to be due to its role in preventing F-actin–induced apoptosis. In this study, we come to a different conclusion. We show that coronin 1 does not modulate F-actin and that induction of F-actin failed to induce apoptosis. Instead, coronin 1 was required for providing prosurvival signals, in the absence of which T cells rapidly underwent apoptosis. These results argue against a role for coronin 1 in F-actin–mediated T cell apoptosis and establish coronin 1 as an essential regulator of the balance between prosurvival and proapoptotic signals in naive T cells

Internal quantum reference frames for finite Abelian groups

Employing internal quantum systems as reference frames is a crucial concept in quantum gravity, gauge theories and quantum foundations whenever external relata are unavailable. In this work, we give a comprehensive and self-contained treatment of such quantum reference frames (QRFs) for the case when the underlying configuration space is a finite Abelian group, significantly extending our previous work (Quantum 5, 530 (2021)). The simplicity of this setup admits a fully rigorous quantum information-theoretic analysis, while maintaining sufficient structure for exploring many of the conceptual and structural questions also pertinent to more complicated setups. We exploit this to derive several important structures of constraint quantization with quantum information-theoretic methods and to reveal the relation between different approaches to QRF covariance. In particular, we characterize the "physical Hilbert space" -- the arena of the "perspective-neutral" approach -- as the maximal subspace that admits frame-independent descriptions of purifications of states. We then demonstrate the kinematical equivalence and, surprising, dynamical inequivalence of the "perspective-neutral" and the "alignability" approach to QRFs. While the former admits unitaries generating transitions between arbitrary subsystem relations, the latter, remarkably, admits no such dynamics when requiring symmetry-preservation. We illustrate these findings by example of interacting discrete particles, including how dynamics can be described "relative to one of the subsystems".Comment: 22 pages, 1 figure. V2: close to published versio

Decision Support for IT Investment Projects - A Real Option Analysis Approach Based on Relaxed Assumptions

Managerial flexibilities have to be taken into account in ex-ante decision-making on IT investment projects (ITIPs). In many papers of the IS literature, standard financial option pricing models are used to value such managerial flexibilities. Based on a review of the related literature, the paper critically discusses the assumptions of the most frequently used financial option pricing model, namely the Black–Scholes model, arguing for relaxed assumptions that better represent the characteristics of ITIPs. The authors find that existing real option analysis approaches featured in the IS, Finance, and Economics literature are unable to consider more than two of our relaxed assumptions. Consequently, they present their own approach in form of a simulation model for the valuation of real options in ITIPs which offers a better representation of the characteristics of ITIPs by taking the discounted cash-flows and the runtime to be uncertain as well as the market to be incomplete. Based on these modifications of the Black–Scholes model’s assumptions, it is found that the resulting option value contains idiosyncratic risk that has to be taken into account in ITIP decision making. For the realistic case of risk averse decision makers, the consideration of idiosyncratic risk usually leads to a lower risk-adjusted option value, compared to one calculated by means of the Black–Scholes model. This confirms the perception of managers who feel that financial option pricing models frequently overvalue ITIPs and hence may induce flawed investment decisions

Problems of bridging plate fixation for the treatment of forearm shaft fractures with the locking compression plate

Introduction: Treatment of diaphyseal forearm fractures by open reduction and internal plate fixation is a well-accepted strategy. In a variety of fracture localizations, the use of bridging plate fixation with locking compression plates (LCP) has been shown to improve biomechanical and biological characteristics. Only very limited clinical data are available on bridging plate fixation using LCPs for the treatment of diaphyseal forearm fractures. The aims of this study were to assess both clinical outcomes of LCP fracture treatments, and the implant-specific advantages and disadvantages. Method: The study consisted of 53 patients. All relevant data were extracted from the medical reports and radiographs. Of the 53 patients, 39 completed the disabilities of the arm, shoulder and hand (DASH) questionnaire and 35 patients were available for clinical examination. The mean time of follow-up was 23.3months. Results: Thirty-nine fractures of the radius and 45 fractures of the ulna were treated with 3.5mm LCPs. Due to a fracture non-union, four patients underwent a second operation. In 13 patients, hardware had already been removed at the time of follow-up. Complete documentation of the removal operation was available for ten patients; in seven of these, procedures difficulties occurred. Mean ranges of motion were 138°, 141° and 162° for elbow flexion-extension, wrist flexion-extension and pronation-supination, respectively. The mean DASH score was calculated at 14.9. Conclusion: In conclusion, our data show that clinical and functional outcomes of LCP plating of diaphyseal forearm fractures are comparable to the use of conventional implants. However, implant-specific problems during hardware removal must be considere

The curse of extremes: generalist career experience and CEO initial compensation

Studies argue that generalist CEOs are more valued by the market for executive labor and receive higher initial compensation. Challenging this prevailing assumption, we acknowledge the drawbacks of extensive career mobility and predict an inverted U-shape relationship between CEO generalist career experience and CEO initial compensation. Integrating the generalism and specialization views of human capital, we postulate that at an initial level, the acquisition of experience-breadth from different firms and industries enables CEOs to broaden their knowledge-base, obtain a variety of skills, and thus increase their labor-market value and initial compensation. After a threshold, however, the accumulation of extensive levels of career generalism through frequent job-hopping across firm and industry contexts gradually causes a lack of experience-depth and insufficient career specialization – thereby triggering lower CEO market-value and initial pay. Data from 197 CEO appointments in large publicly traded firms support our predictions. Our results also show that the observed inverted U-shape relationship varies with factors nested at different layers of context – highlighting the contingent nature of this area of research