"Asymmetric Market Shares, Advertising, and Pricing: Equilibrium with an Information Gatekeeper"

We analyze the impact of market share on advertising and pricing decisions by firms that sell to loyal, non-shopping customers and can advertise to shoppers through an information intermediary or "gatekeeper." In equilibrium the firm with the smaller loyal market advertises more aggressively but prices less competitively than the firm with the larger loyal market, and there is no equilibrium in which both firms advertise with probability 1. The results differ significantly from earlier literature which assumes all prices are revealed to shoppers and finds that the firm with the smaller loyal market adopts a more competitive pricing strategy. The predictions of the model are consistent with advertising and pricing behavior observed on price comparison websites such as Shopper.com.online markets, E-commerce, market share, information gatekeeper, equilibrium price dispersion, advertising

The Veterans Affairs Neuropathy Scale: A Reliable, Remote Polyneuropathy Exam.

Introduction: Polyneuropathy (PN) complaints are common, prompting many referrals for neurologic evaluation. To improve access of PN care in distant community clinics, we developed a telemedicine service (patient-clinician interactions using real-time videoconference technology) for PN. The primary goal of this study was to construct a remote exam for PN that is feasible, reliable, and concordant with in-person assessments for use in our tele-PN clinics. Methods: To construct the VA Neuropathy Scale (VANS), we searched the literature for existing, validated PN assessments. From these assessments, we selected a parsimonious set of exam elements based on literature-reported sensitivity and specificity of PN detection, with modifications as necessary for our teleneurology setting (i.e., a technician examination under the direction of a neurologist). We recruited 28 participants with varying degrees of PN to undergo VANS testing under 5 scenarios. The 5 scenarios differed by mode of VANS grading (in-person vs. telemedicine) and by the in-person examiner type (neurologist vs. technician) in telemedicine scenarios. We analyzed concordance between the VANS and a person's medical chart-derived PN status by modeling the receiver operating characteristic (ROC) curve. We analyzed reliability of the VANS by mixed effects regression and computing the intraclass correlation coefficient (ICC) of scores across the 5 scenarios. Results: The VA Neuropathy Scale (VANS) tests balance, gait, reflexes, foot inspection, vibration, and pinprick. Possible scores range from 0 to 50 (worst). From the ROC curve, a cutoff of >2 points on the VANS sets the sensitivity and specificity of detecting PN at 98 and 91%, respectively. There is a small (1.3 points) but statistically significant difference in VANS scoring between in-person and telemedicine grading scenarios. For telemedicine grading scenarios, there is no difference in VANS scores between neurologist and technician examinations. The ICC is 0.89 across all scenarios. Discussion: The VANS, informed by existing PN instruments, is a promising clinical assessment tool for diagnosing and monitoring the severity of PN in telemedicine settings. This pilot study indicates acceptable concordance and reliability of the VANS with in-person examinations

Welcoming the First Decade of Perovskite Solar Cells

The swift emergence of perovskite solar cells (PSCs) is a “miracle” development in the history of photovoltaics. Since Miyasaka and co‐workers (Toin University of Yokohama, Japan) reported the first use of halide perovskites (HPs) in solar cells in 2009, the past ten years have witnessed a skyrocketing increase in power conversion efficiency (PCE) to 24.2% for single‐junction PSCs and 28.0% for Si‐perovskite tandem solar cells

Ionic polarization-induced current-voltage hysteresis in ch3nh3pbx3 perovskite solar cells

CH3NH3PbX3 (MAPbX3) perovskites have attracted considerable attention as absorber materials for solar light harvesting, reaching solar to power conversion efficiencies above 20%. In spite of the rapid evolution of the efficiencies, the understanding of basic properties of these semiconductors is still ongoing. One phenomenon with so far unclear origin is the so-called hysteresis in the current–voltage characteristics of these solar cells. Here we investigate the origin of this phenomenon with a combined experimental and computational approach. Experimentally the activation energy for the hysteretic process is determined and compared with the computational results. First-principles simulations show that the timescale for MAþ rotation excludes a MA-related ferroelectric effect as possible origin for the observed hysteresis. On the other hand, the computationally determined activation energies for halide ion (vacancy) migration are in excellent agreement with the experimentally determined values, suggesting that the migration of this species causes the observed hysteretic behaviour of these solar cells