Mergers among leaders and mergers among followers

We are the first to confirm that sufficient cost convexity in a Stackelberg model generates profitable mergers between two leaders and between two followers. Moreover, the degree of convexity required for leaders to merge is generally far smaller than that required for followers. Most importantly, the structure of the stage game means that the convexity required for either two followers or two leaders to merge is less than that required for two Cournot competitors.

Clear Skies: Multi-Pollutant Climate Policy in the Presence of Global Dimming

Publisher PD

Emissions Trading and Intersectoral Dynamics: Absolute versus Relative Design Schemes

This paper examines the interdependence between imperfect competition and emis- sions trading in a two-sector (clean and dirty) economy. We compare the welfare implica- tions of an absolute cap-and-trade scheme (permit trading) with a relative intensity-based scheme (credit trading). We nd unambiguously more clean rms in the long run under credit trading. However, neither emissions trading con guration creates the rst-best out- come: there are too few (many) clean rms under permit (credit) trading. Permit trading dominates credit trading in terms of overall welfare at the long run equilibrium, except when policy is relatively lenient. It is also demonstrated that stricter policy does not necessarily induce the clean sector to grow relative to the dirty sector and we determine under what conditions this holds

Enabling Lightweight Video Annotation and Presentation for Cultural Heritage

Collaboration-intensive research is increasingly becoming the norm in the humanities and social science arenas. eResearch tools such as online repositories offer researchers the opportunity to access and interact with data online. For the last 20 years video has formed an important part of humanities research, although dealing with multimedia in an online setting has proven difficult with existing tools. File size limitations, lack of interoperability with existing security systems, and the inability to include rich supportive detail regarding files have hampered the use of video. This paper describes a collaborative and data management solution for video and other files using a combination of existing tools (SRB and Plone integrated with Shibboleth) and a custom application for video upload and annotation (Mattotea). Rather than creating new proprietary systems, this development has examined the reuse of existing technologies with the addition of custom extensions to provide fullfeatured access to research data

CT/MRI and CEUS LI-RADS Major Features Association with Hepatocellular Carcinoma: Individual Patient Data Meta-Analysis

Background The Liver Imaging Reporting and Data System (LI-RADS) assigns a risk category for hepatocellular carcinoma (HCC) to imaging observations. Establishing the contributions of major features can inform the diagnostic algorithm. Purpose To perform a systematic review and individual patient data meta-analysis to establish the probability of HCC for each LI-RADS major feature using CT/MRI and contrast-enhanced US (CEUS) LI-RADS in patients at high risk for HCC. Materials and Methods Multiple databases (MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus) were searched for studies from January 2014 to September 2019 that evaluated the accuracy of CT, MRI, and CEUS for HCC detection using LI-RADS (CT/MRI LI-RADS, versions 2014, 2017, and 2018; CEUS LI-RADS, versions 2016 and 2017). Data were centralized. Clustering was addressed at the study and patient levels using mixed models. Adjusted odds ratios (ORs) with 95% CIs were determined for each major feature using multivariable stepwise logistic regression. Risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) (PROSPERO protocol: CRD42020164486). Results A total of 32 studies were included, with 1170 CT observations, 3341 MRI observations, and 853 CEUS observations. At multivariable analysis of CT/MRI LI-RADS, all major features were associated with HCC, except threshold growth (OR, 1.6; 95% CI: 0.7, 3.6; P = .07). Nonperipheral washout (OR, 13.2; 95% CI: 9.0, 19.2; P = .01) and nonrim arterial phase hyperenhancement (APHE) (OR, 10.3; 95% CI: 6.7, 15.6; P = .01) had stronger associations with HCC than enhancing capsule (OR, 2.4; 95% CI: 1.7, 3.5; P = .03). On CEUS images, APHE (OR, 7.3; 95% CI: 4.6, 11.5; P = .01), late and mild washout (OR, 4.1; 95% CI: 2.6, 6.6; P = .01), and size of at least 20 mm (OR, 1.6; 95% CI: 1.04, 2.5; P = .04) were associated with HCC. Twenty-five studies (78%) had high risk of bias due to reporting ambiguity or study design flaws. Conclusion Most Liver Imaging Reporting and Data System major features had different independent associations with hepatocellular carcinoma; for CT/MRI, arterial phase hyperenhancement and washout had the strongest associations, whereas threshold growth had no association. © RSNA, 2021 Online supplemental material is available for this article

Detailed description of Division I ice hockey concussions: Findings from the NCAA and Department of Defense CARE Consortium

Objective: Since concussion is the most common injury in ice hockey, the objective of the current study was to elucidate risk factors, specific mechanisms, and clinical presentations of concussion in men's and women's ice hockey. Methods: Ice hockey players from 5 institutions participating in the Concussion Assessment, Research, and Education Consortium were eligible for the current study. Participants who sustained a concussion outside of this sport were excluded. There were 332 (250 males, 82 females) athletes who participated in ice hockey, and 47 (36 males, 11 females) who sustained a concussion. Results: Previous concussion (odds ratio (OR) = 2.00; 95% confidence interval (95% CI): 1.02‒3.91) was associated with increased incident concussion odds, while wearing a mouthguard was protective against incident concussion (OR = 0.43; 95%CI: 0.22‒0.85). Overall, concussion mechanisms did not significantly differ between sexes. There were specific differences in how concussions presented clinically across male and female ice hockey players, however. Females (9.09%) were less likely than males (41.67%) to have a delayed symptom onset (p = 0.045). Additionally, females took significantly longer to reach asymptomatic (p = 0.015) and return-to-play clearance (p = 0.005). Within the first 2 weeks post-concussion, 86.11% of males reached asymptomatic, while only 45.50% of females reached the same phase of recovery. Most males (91.67%) were cleared for return to play within 3 weeks of their concussion, compared to less than half (45.50%) of females. Conclusion: The current study proposes possible risk factors, mechanisms, and clinical profiles to be validated in future concussions studies with larger female sample sizes. Understanding specific risk factors, concussion mechanisms, and clinical profiles of concussion in collegiate ice hockey may generate ideas for future concussion prevention or intervention studies

Contribution of Genetic Background, Traditional Risk Factors, and HIV-Related Factors to Coronary Artery Disease Events in HIV-Positive Persons

We show in human immunodeficiency virus-positive persons that the coronary artery disease effect of an unfavorable genetic background is comparable to previous studies in the general population, and comparable in size to traditional risk factors and antiretroviral regimens known to increase cardiovascular ris