Agenda chasing and contests among news providers

This article studies competition in contests with a focus on the news industry that is increasingly influenced by social media. The model assumes publishers to pick a single topic from a large pool based on the topics' prior “success” probabilities, thereby “chasing” potentially successful topics. Firms that publish topics that become successful divide a “reward” which can change with the number of competing firms and the number of successful topics. The results show that share structures can be categorized into three types that, in turn, lead to qualitatively different outcomes for the contest

Towards a Spectroscopic Protocol for Unambiguous Detection of Quantum Coherence in Excitonic Energy Transport

The role of quantum effects in excitonic energy transport (EET) has been scrutinised intensely and with increasingly sophisticated experimental techniques. This increased complexity requires invoking correspondingly elaborate models to fit spectroscopic data before molecular parameters can be extracted. Possible quantum effects in EET can then be studied, but the conclusions are strongly contingent on the efficacy of the fitting and the accuracy of the model. To circumvent this challenge, we propose a witness for quantum coherence in EET that can be extracted directly from two-pulse pump-probe spectroscopy experimental data. We provide simulations to judge the feasibility of our approach. Somewhat counterintuitively, our protocol does not probe quantum coherence directly, but only indirectly through its implicit deletion. It allows for classical models with no quantum coherence to be decisively ruled out.Comment: 13 pages, 9 figure

Quantum leakage detection using a model-independent dimension witness

Users of quantum computers must be able to confirm they are indeed functioning as intended, even when the devices are remotely accessed. In particular, if the Hilbert space dimension of the components are not as advertised -- for instance if the qubits suffer leakage -- errors can ensue and protocols may be rendered insecure. We refine the method of delayed vectors, adapted from classical chaos theory to quantum systems, and apply it remotely on the IBMQ platform -- a quantum computer composed of transmon qubits. The method witnesses, in a model-independent fashion, dynamical signatures of higher-dimensional processes. We present evidence, under mild assumptions, that the IBMQ transmons suffer state leakage, with a $p$ value no larger than $5{\times}10^{-4}$ under a single qubit operation. We also estimate the number of shots necessary for revealing leakage in a two-qubit system.Comment: 11 pages, 5 figure

Segond's fracture: a biomechanical cadaveric study using navigation

Background Segond’s fracture is a well-recognised radiological sign of an anterior cruciate ligament (ACL) tear. While previous studies evaluated the role of the anterolateral ligament (ALL) and complex injuries on rotational stability of the knee, there are no studies on the biomechanical effect of Segond’s fracture in an ACL deficient knee. The aim of this study was to evaluate the effect of a Segond’s fracture on knee rotation stability as evaluated by a navigation system in an ACL deficient knee. Materials and methods Three different conditions were tested on seven knee specimens: intact knee, ACL deficient knee and ACL deficient knee with Segond’s fracture. Static and dynamic measurements of anterior tibial translation (ATT) and axial tibial rotation (ATR) were recorded by the navigation system (2.2 OrthoPilot ACL navigation system B. Braun Aesculap, Tuttlingen, Germany). Results Static measurements at 30 showed that the mean ATT at 30 of knee flexion was 5.1 ± 2.7 mm in the ACL intact condition, 14.3 ± 3.1 mm after ACL cut (P = 0.005), and 15.2 ± 3.6 mm after Segond’s fracture (P = 0.08). The mean ATR at 30 of knee flexion was 20.7 ± 4.8 in the ACL intact condition, 26.9 ± 4.1 in the ACL deficient knee (P[0.05) and 30.9 ± 3.8 after Segond’s fracture (P = 0.005). Dynamic measurements during the pivot-shift showed that the mean ATT was 7.2 ± 2.7 mm in the intact knee, 9.1 ± 3.3 mm in the ACL deficient knee(P = 0.04) and 9.7 ± 4.3 mm in the ACL deficient knee with Segond’s fracture (P = 0.07). The mean ATR was 9.6 ± 1.8 in the intact knee, 12.3 ± 2.3 in the ACL deficient knee (P[0.05) and 19.1 ± 3.1 in the ACL deficient knee with Segond’s lesion (P = 0.016). Conclusion An isolated lesion of the ACL only affects ATT during static and dynamic measurements, while the addition of Segond’s fracture has a significant effect on ATR in both static and dynamic execution of the pivot-shift test, as evaluated with the aid of navigation

An exploratory study into the effects of a 20 minute crushed ice application on knee joint position sense during a small knee bend.

Objectives The effect of cryotherapy on joint positioning presents conflicting debates as to whether individuals are at an increased risk of injury when returning to play or activity immediately following cryotherapy application at the knee. The aim of this study was to investigate whether a 20 minute application of crushed ice at the knee immediately affects knee joint position sense during a small knee bend. Design Pre and post-intervention. Setting University movement analysis laboratory. Participants Eleven healthy male participants. Main Outcome Measures Kinematics of the knee were measured during a weight bearing functional task pre and post cryotherapy intervention using three-dimensional motion analysis (Qualisys Medical AB Gothenburg, Sweden). Tissue cooling was measured via a digital thermometer at the knee. Results Results demonstrated significant reductions in the ability to accurately replicate knee joint positioning in both sagittal (P=.035) and coronal (P=.011) planes during the descent phase of a small knee bend following cryotherapy. Conclusion In conclusion a twenty minute application of crushed ice to the knee has an adverse effect on knee joint repositioning. Team doctors, clinicians, therapists and athletes should consider these findings when deciding to return an athlete to functional weight bearing tasks immediately following ice application at the knee, due to the potential increase risk of injury

Association of malalignment, muscular dysfunction, proprioception, laxity and abnormal joint loading with tibiofemoral knee osteoarthritis - a systematic review and meta-analysis

Background: To investigate (1) the association of specific biomechanical factors with knee osteoarthritis and knee osteoarthritis development, and (2) the impact of other relevant risk factors on this association.Methods: MEDLINE, EMBASE, CINAHL and SPORTDiscus were searched up until April 2017. Studies were included if they fulfilled the following criteria: the study 1) assessed the association of a biomechanical factor with knee osteoarthritis, or knee osteoarthritis development; 2) reported on skeletal malalignment, muscular dysfunction, impaired proprioception, laxity and abnormal loading during gait; 3) was a cohort study with participants developing knee osteoarthritis and participants not developing knee osteoarthritis, or a case-control or cross-sectional study with participants with knee osteoarthritis and without knee osteoarthritis. Risk of bias was assessed with the QUIPS tool and meta-analyses were performed using random effects models.Results: Of 6413 unique studies identified, 59 cross-sectional studies were eligible for meta-analyses (9825 participants, 5328 with knee osteoarthritis). No cohort studies fulfilled the inclusion criteria. Compared with healthy controls, patients with knee osteoarthritis have higher odds of having lower muscle strength, proprioception deficits, more medial varus-valgus laxity and less lateral varus-valgus laxity. Patients with medial knee osteoarthritis have higher odds of having a higher knee adduction moment than healthy controls. Level of evidence was graded as 'very low' to 'moderate' quality. Due to large between study differences moderation of other risk factors on biomechanical risk factors could not be evaluated.Conclusions: Patients with knee osteoarthritis are more likely to display a number of biomechanical characteristics. The causal relationship between specific biomechanical factors and the development of knee osteoarthritis could not be determined as no longitudinal studies were included. There is an urgent need for high quality, longitudinal studies to evaluate the impact of specific biomechanical factors on the development of knee osteoarthritis.Trial Registration: (PROSPERO ID: CRD42015025092)

Secondary resurfacing of the patella in total knee arthroplasty

Anterior knee pain following primary total knee arthroplasty is common and can be difficult to treat satisfactorily. We reviewed 28 consecutive patients (29 knees) who underwent secondary resurfacing of the patella for persistent anterior knee pain and report on the results. Mean follow-up was 28 months (range12-61) with no cases lost to follow-up. Oxford knee scores, range of motion, the patient's assessment of outcome and overall satisfaction were recorded. Seventeen out of 19 (59%) felt their knee was better following patellar resurfacing, 10 out of 29 (34%) felt it was the same and two out of 29 (7%) felt it was worse. There was a significant improvement in Oxford knee scores (p < 0.001) and significant increase in patient satisfaction (p < 0.001) following secondary resurfacing. While secondary resurfacing of the patella does not provide the solution for every case of anterior knee pain following total knee joint replacement, in greater than 50% of cases it can be effective at relieving symptoms and in this series carries a low risk of worsening symptoms or complications