N=2 Quantum Field Theories and their BPS quivers

We explore the relationship between four-dimensional N = 2 quantum field theories and their associated BPS quivers. For a wide class of theories including super-Yang-Mills theories, Argyres- Douglas models, and theories defined by M5-branes on punctured Riemann surfaces, there exists a quiver which implicitly characterizes the field theory. We study various aspects of this correspondence including the quiver interpretation of flavor symmetries, gauging, decoupling limits, and field theory dualities. In general a given quiver describes only a patch of the moduli space of the field theory, and a key role is played by quantum mechanical dualities, encoded by quiver mutations, which relate distinct quivers valid in different patches. Analyzing the consistency conditions imposed on the spectrum by these dualities results in a powerful and novel mutation method for determining the BPS states. We apply our method to determine the BPS spectrum in a wide class of examples, including the strong coupling spectrum of super-Yang-Mills with an ADE gauge group and fundamental matter, and trinion theories defined by M5-branes on spheres with three punctures. \ua9 2014 International Press

Pulsatile blood flow, shear force, energy dissipation and Murray's Law

BACKGROUND: Murray's Law states that, when a parent blood vessel branches into daughter vessels, the cube of the radius of the parent vessel is equal to the sum of the cubes of the radii of daughter blood vessels. Murray derived this law by defining a cost function that is the sum of the energy cost of the blood in a vessel and the energy cost of pumping blood through the vessel. The cost is minimized when vessel radii are consistent with Murray's Law. This law has also been derived from the hypothesis that the shear force of moving blood on the inner walls of vessels is constant throughout the vascular system. However, this derivation, like Murray's earlier derivation, is based on the assumption of constant blood flow. METHODS: To determine the implications of the constant shear force hypothesis and to extend Murray's energy cost minimization to the pulsatile arterial system, a model of pulsatile flow in an elastic tube is analyzed. A new and exact solution for flow velocity, blood flow rate and shear force is derived. RESULTS: For medium and small arteries with pulsatile flow, Murray's energy minimization leads to Murray's Law. Furthermore, the hypothesis that the maximum shear force during the cycle of pulsatile flow is constant throughout the arterial system implies that Murray's Law is approximately true. The approximation is good for all but the largest vessels (aorta and its major branches) of the arterial system. CONCLUSION: A cellular mechanism that senses shear force at the inner wall of a blood vessel and triggers remodeling that increases the circumference of the wall when a shear force threshold is exceeded would result in the observed scaling of vessel radii described by Murray's Law

Heading Frequency and Risk of Cognitive Impairment in Retired Male Professional Soccer Players

Importance Although professional soccer players appear to be at higher risk of neurodegenerative disease, the reason remains unknown.Objective To examine whether heading frequency is associated with risk of cognitive impairment in retired professional soccer players.Design, Setting, and Participants A UK nationwide cross-sectional study was conducted between August 15, 2020, and December 31, 2021, in 459 retired male professional soccer players older than 45 years and registered with the Professional Footballers’ Association or a League Club Players’ Association.Exposure Data on heading frequency in 3 bands—0 to 5, 6 to 15, and more than 15 times per match or training session and other soccer-specific risk factors, such as player position and concussion—were collected through a self-reported questionnaire.Main Outcomes and Measures Cognitive impairment was defined using the Telephone Interview for Cognitive Status-modified as scores of less than or equal to 21. Hopkins Verbal Learning Test, verbal fluency, and independent activities of daily living were also assessed. Test Your Memory and physician-diagnosed dementia/Alzheimer disease were self-reported via the questionnaire. Adjusted odds ratios (AORs) with 95% CIs were calculated.Results Of 468 retired male professional soccer players who completed questionnaires (mean [SD] age, 63.68 [10.48]; body mass index, 27.22 [2.89]), 459 reported heading frequency: 114 headed 0 to 5 times, 185 headed 6 to 15 times, 160 headed more than 15 times per match, and 125 headed 0 to 5 times, 174 headed 6 to 15 times, and 160 headed more than 15 times per training session during their careers. The prevalence of cognitive impairment was 9.78% (0-5 times), 14.78% (6-15 times), and 15.20% (>15 times) per match (P = .51). Compared with players reporting 0 to 5 headers per match, the AORs were 2.71 (95% CI, 0.89-8.25) for players reporting 6 to 15 headers per match and 3.53 (95% CI, 1.13-11.04) for players reporting more than 15 headers per match (P = .03 for trend). Corresponding AORs for heading frequency per training session were 2.38 (95% CI, 0.82-6.95) for those reporting 6 to 15, and 3.40 (95% CI, 1.13-10.23) for those reporting more than 15 in comparison with those who reported 0 to 5 (P = .03 for trend). Concussion involving memory loss was also associated with a greater risk of cognitive impairment (AOR, 3.16; 95% CI, 1.08-9.22). Similar results were observed with other cognitive tests and self-reported physician-diagnosed dementia/Alzheimer disease.Conclusions and Relevance The findings of this study suggest that repetitive heading during a professional soccer career is associated with an increased risk of cognitive impairment in later life. Further study is needed to establish the upper threshold for heading frequency to mitigate this risk

Injury and local injection and the risk of foot/ankle osteoarthritis: a case–control study in retired UK male professional footballers

Objective The objective of this study was to examine whether foot/ankle injury and injection contribute to the risk of foot/ankle OA in retired UK male professional footballers. Methods This was a case–control study among retired UK male footballers, in which cases reported General Practitioner–diagnosed foot/ankle OA or forefoot/ankle surgery after retirement, and controls reported neither. Injury was defined as significant foot/ankle injury with pain for most days over 3 months during their career. Injection was defined as injection of corticosteroids or other agents into foot/ankle joints during their career. Adjusted odds ratios (aORs) with 95% confidence interval (CIs) were calculated using logistic regression. Areas Under the Curve (AUCs) and 95% CIs were estimated to examine the contribution of injury and/or injection in the context of other available risk factors. Results Of 424 footballers studied, 63 had foot/ankle OA and 361 had neither. Cases had similar mean age (63.2 vs 63.0, P = 0.457) and BMI (27.7 vs 27.0, P = 0.240) to those of controls, but more foot/ankle injury (73.3% vs 42.5%, P < 0.001) and injections (75.0% vs 48.4%, P < 0.001), with aORs of 4.23 (95% CI 1.88–9.48) and 2.62 (95% CI 1.19–5.78), respectively. The AUC was 0.69 (95% CI 0.62–0.77) for injury, 0.74 (95% CI 0.66–0.81) for injury and injection, and 0.78 (95% CI 0.70–0.85) for all risk factors. Similar results were observed in footballers with ankle OA only. Conclusion Injury was a major risk factor for foot/ankle OA in retired UK male professional footballers. The role of injection needs cautious interpretation due to potential confounding by indication

The Role of Information and Financial Reporting in Corporate Governance and Debt Contracting

We review recent literature on the role of financial reporting transparency in reducing governance-related agency conflicts among managers, directors, and shareholders, as well as in reducing agency conflicts between shareholders and creditors, and offer researchers some suggested avenues for future research. Key themes include the endogenous nature of debt contracts and governance mechanisms with respect to information asymmetry between contracting parties, the heterogeneous nature of the informational demands of contracting parties, and the heterogeneous nature of the resulting governance and debt contracts. We also emphasize the role of a commitment to financial reporting transparency in facilitating informal multiperiod contracts among managers, directors, shareholders, and creditors

Numerical solution for one-dimensional pure-convection problems using the high-order Taylor-Galerkin element-free method

The present study proposes a novel approach for solving one-dimensional pure convection problems, utilizing a high-order Taylor Galerkin element-free method. The standard Galerkin method has limitations in solving such problems due to the predominance of convective terms over diffusion terms, leading to unstable and fluctuating analysis results over time. To address this issue, high-order stabilizing terms can be added to the standard Galerkin method. However, due to the limitations in the derivability of the standard Galerkin shape function, it is not possible to incorporate high-order terms in the equation. In this context, the proposed high-order Taylor Galerkin element-free method enables the inclusion of stabilizing terms with high-order derivatives in the equations, utilizing the moving least-squares (MLS) shape function and exponential weight function, which exhibit the continuity of all their derivatives. This approach provides a promising solution for addressing the limitations of the finite element method and achieving more accurate and stable analysis results for one-dimensional pure convection problems. The accuracy of the numerical simulation was evaluated using two one-dimensional pure convection benchmark problems: the Gaussian wave motion problem and the classical water hammer problem, both analyzed up to the fourth-order. The results of the numerical simulations demonstrated that increasing the number of stabilizing terms led to improved accuracy and decreased fluctuations. Therefore, it can be concluded that the stability terms up to the fourth-order in the equations display acceptable accuracy for these two problems. This development has significant implications for the analysis of fluid mechanics and other related phenomena. By enabling a more comprehensive analysis of fluid dynamics, researchers can investigate complex fluid dynamics with greater precision and detail, yielding valuable insights into a wide range of physical processes. In conclusion, the proposed high-order Taylor Galerkin element-free method is a noteworthy advancement in numerical analysis, overcoming the limitations of the standard Galerkin method and demonstrating superior accuracy and stability in the solution of pure convection problems. This approach provides an efficient and accurate method for numerical analysis and has the potential to be extended to other areas of research, including computational fluid dynamics, heat transfer, and structural mechanics

The audit reporting model: current research synthesis and implications

This research synthesis evaluates relevant research concerning the audit report. For too long, there has been a significant “expectations gap” between what financial statement users expect an audit is delivering and what the audit profession believes it is providing. This gap becomes particularly problematic for auditors when there is a “business crisis” and attention is directed to the role of the auditor. Two related gaps are considered in this synthesis, a communications gap, and an information gap. All of these gaps relate to the demand for, understanding of, and use of auditor communications, which is the focus of this synthesis. Our synthesis is driven by two primary research questions: What do financial statement users perceive as information that should be communicated, and what does research show to be the effects on users of existing and other auditor communications currently being considered? As we discuss in detail, prior research does address many aspects of these two questions, but many of the findings are mixed and some important aspects have not been studied. Further research, particularly in areas regarding changes to the audit reporting model currently being considered, could lead to the improvement of the value relevance of auditor services, disclosures, and assurances. The clear interest by regulators and standard setters in such applied research should serve as a strong incentive for academics to conduct such research and for the practicing profession to support it.Theodore J. Mock, Jean Bédard, Paul J. Coram, Shawn M. Davis, Reza Espahbodi and Rick C. Warn

The audit reporting model: current research synthesis and implications

This research synthesis evaluates relevant research concerning the audit report. For too long, there has been a significant “expectations gap” between what financial statement users expect an audit is delivering and what the audit profession believes it is providing. This gap becomes particularly problematic for auditors when there is a “business crisis” and attention is directed to the role of the auditor. Two related gaps are considered in this synthesis, a communications gap, and an information gap. All of these gaps relate to the demand for, understanding of, and use of auditor communications, which is the focus of this synthesis. Our synthesis is driven by two primary research questions: What do financial statement users perceive as information that should be communicated, and what does research show to be the effects on users of existing and other auditor communications currently being considered? As we discuss in detail, prior research does address many aspects of these two questions, but many of the findings are mixed and some important aspects have not been studied. Further research, particularly in areas regarding changes to the audit reporting model currently being considered, could lead to the improvement of the value relevance of auditor services, disclosures, and assurances. The clear interest by regulators and standard setters in such applied research should serve as a strong incentive for academics to conduct such research and for the practicing profession to support it.Theodore J. Mock, Jean Bédard, Paul J. Coram, Shawn M. Davis, Reza Espahbodi, and Rick C. Warn