HIV infection and increased risk of COVID-19 mortality: A Meta-Analysis

There are some concerns on the effect of infection with human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) on the outcome and mortality of COVID-19. In this meta-analysis, we aimed to address this issue and assess the risk of mortality in COVID-19 patients who are co-infected with HIV. Two International electronic databases (PubMed, Scopus) were searched from the first time available to 12 August 2021. The targeted outcome was the pooled odds ratio to examine the effect of HIV infection on COVID-19 mortality. The crude odds ratio (OR) for all studies and the pooled OR were calculated with 95% confidence interval. The forest plot was used to graphically represent the result of conducted meta-analysis and calculated OR for individual studies. The I2 statistic was used to examine the Heterogeneity in the included studies. Eleven studies were included in our study consisting of 19,642,775 COVID-19 infected cases, 59,980 HIV-positive, and 4,373 deaths due to COVID-19 in HIV positive patients. The overall pooled odds ratio was 1.21 (CI: 1.02; 1.43) and P-value < 0.0277. The I^2 value was 89% (P-value < 0.0001), which shows that included studies are heterogeneous. In this study, the funnel plot analysis showed symmetry among the included studies. HIV-positive patients are 21% more likely to die because of COVID-19 infection than people without HIV. Special attention should be considered for the prevention and treatment of COVID-19 and consistent treatment for HIV infection, in HIV-positive patients.

Description and evaluation of the community aerosol dynamics model MAFOR v2.0

Numerical models are needed for evaluating aerosol processes in the atmosphere in state-of-the-art chemical transport models, urban-scale dispersion models and climatic models. This article describes a publicly available aerosol dynamics model MAFOR (Multicomponent Aerosol FORmation model; version 2.0); we address the main structure of the model, including the types of operation and the treatments of the aerosol processes. The main advantage of MAFOR v2.0 is the consistent treatment of both the mass- and number-based concentrations of particulate matter. An evaluation of the model is also presented, against a high-resolution observational dataset in a street canyon located in the centre of Helsinki (Finland) during an afternoon traffic rush hour on 13 December 2010. The experimental data included measurements at different locations in the street canyon of ultrafine particles, black carbon, and fine particulate mass PM1. This evaluation has also included an intercomparison with the corresponding predictions of two other prominent aerosol dynamics models, AEROFOR and SALSA. All three models fairly well simulated the decrease of the measured total particle number concentrations with increasing distance from the vehicular emission source. The MAFOR model reproduced the evolution of the observed particle number size distributions more accurately than the other two models. The MAFOR model also predicted the variation of the concentration of PM1 better than the SALSA model. We also analysed the relative importance of various aerosol processes based on the predictions of the three models. As expected, atmospheric dilution dominated over other processes; dry deposition was the second most significant process. Numerical sensitivity tests with the MAFOR model revealed that the uncertainties associated with the properties of the condensing organic vapours affected only the size range of particles smaller than 10 nm in diameter. These uncertainties do not therefore affect significantly the predictions of the whole of the number size distribution and the total number concentration. The MAFOR model version 2 is well documented and versatile to use, providing a range of alternative parametrizations for various aerosol processes. The model includes an efficient numerical integration of particle number and mass concentrations, an operator-splitting of processes, and the use of a fixed sectional method. The model could be used as a module in various atmospheric and climatic models.

Evolutionary understanding of airfoil lift

This review attempts to elucidate the physical origin of aerodynamic lift of an airfoil using simple formulations and notations, particularly focusing on the critical effect of the fluid viscosity. The evolutionary development of the lift problem of a flat-plate airfoil is reviewed as a canonical case from the classical inviscid circulation theory to the viscous-flow model. In particular, the physical aspects of the analytical expressions for the lift coefficient of the plate-plate airfoil are discussed, including Newton’s sine-squared law, Rayleigh’s lift formula, thin-airfoil theory and viscous-flow lift formula. The vortex-force theory is described to provide a solid foundation for consistent treatment of lift, form drag, Kutta condition, and downwash. The formation of the circulation and generation of lift are discussed based on numerical simulations of a viscous starting flow over an airfoil, and the evolution of the flow topology near the trailing edge is well correlated with the realization of the Kutta condition. The presented contents are valuable for the pedagogical purposes in aerodynamics and fluid mechanics.

Rare Tumors in Children and Adolescents – the STEP Working Groupʼs Evolution to a Prospective Registry

Background Very rare tumors (VRT) in children and adolescents have such a low incidence that until recently, they have not been integrated into the clinical and scientific network of pediatric oncology. Data is very limited and consistent treatment strategies are missing. Thus, VRTs are classic orphan diseases. To counteract this problem, the Arbeitsgemeinschaft für Seltene Tumorerkrankungen in der Pädiatrie (STEP) was founded. Here we report on patient recruitment during the first 10 years. Patients Patients aged up to 18 years and not included in any other clinical trial or GPOH registry were included in this analysis. Methods Data was collected from 2008 to 2018 by means of a standardized form. The recorded diagnoses were descriptively analyzed focusing on histology, localization, and year of report. Results A total of 623 patients with VRTs were registered. During 2008–2014, the annual number of registrations was around 40 and is around 90 since 2015. Most frequent diagnoses included tumors of the skin (n=150), tumors of the gastrointestinal tract (n=102), tumors of the gonads (n=77), the ENT region (n=68), and miscellaneous tumors (n=107). Discussion With the establishment of central structures for clinical consultation and documentation of VRTs, the number of registrations increased. Comprehensively, VRTs are as common as other classic pediatric oncology tumors, but extremely heterogeneous in terms of localization, histology, and prognosis. By a centralized and complete registration and analysis of VRTs, also in collaboration with international partners, it is possible to develop treatment strategies and thus greatly increase treatment quality.

Instabilities and sensitivities in a flow over a rotationally flexible cylinder with a rigid splitter plate

This paper investigates the origin of flow-induced instabilities and their sensitivities in a flow over a rotationally flexible circular cylinder with a rigid splitter plate. A linear stability and sensitivity problem is formulated in the Eulerian frame by considering the geometric nonlinearity arising from the rotational motion of the cylinder which is not present in the stationary or purely translating stability methodology. This nonlinearity needs careful and consistent treatment in the linearised problem particularly when considering the Eulerian frame or reference adopted in this study that is not so widely considered. Two types of instabilities arising from the fluid–structure interaction are found. The first type of instabilities is the stationary symmetry breaking mode, which was well reported in previous studies. This instability exhibits a strong correlation with the length of the recirculation zone. A detailed analysis of the instability mode and its sensitivity reveals the importance of the flow near the tip region of the plate for the generation and control of this instability mode. The second type is an oscillatory torsional flapping mode, which has not been well reported. This instability typically emerges when the length of the splitter plate is sufficiently long. Unlike the symmetry breaking mode, it is not so closely correlated with the length of the recirculation zone. The sensitivity analysis however also reveals the crucial role played by the flow near the tip region in this instability. Finally, it is found that many physical features of this instability are reminiscent of those of the flapping (or flutter instability) observed in a flow over a flexible plate or a flag, suggesting that these instabilities share the same physical origin.

The 2021 Korean Heart Rhythm Society Guidelines for a New Approach and Integrated Management of Atrial Fibrillation

The prevalence of atrial fibrillation (AF) is gradually increasing with the aging of the population, and there is also increasing interest in AF with the development of various single-lead electrocardiography measurement methods for diagnosis. Further, the current diagnosis and treatment policies for AF do not reflect its progression and complexity. In addition, the various factors related to AF diagnosis and treatment are not simple due to the diversification of tools, advances in treatment methods, and complex mechanism of AF. Therefore, there are many challenges to developing a simple AF classification system. To overcome these, there have been a number of attempts to systematically characterize AF according to treatment and prognosis rather than using a uniform classification. Further, as mentioned in the previous AF guidelines, further research is being conducted on an integrated patient–physician approach to AF. Such an approach would be the basis for consistent treatment based on the guidelines, and would help to improve patient outcomes. Further, for the integrated management of AF patients, some changes should be made to the current approach to develop a multidisciplinary approach, including changes to the behavior of team members, patients, their family members, and physicians. The Korean Heart Rhythm will introduce an integrated approach to the classification and structure of AF management, and provide guidelines for its application in clinical practice.

THE APPLICATION OF CONSISTENCY OF TREATMENT IN DISMISSALS FOR MISCONDUCT

Fairness in employment necessitates that the employer apply consistent disciplinary standards in the workplace, so that employees who commit the same or similar disciplinary infraction are treated equally. The Code of Good Practice: Dismissal (in Schedule 8 of the Labour Relations Act 55 of 1995) sets out a range of guidelines to be applied by the employer before a decision to dismiss an employer may be taken. It seeks to protect employees from arbitrary action by the employer in order to achieve a measure of employment justice. Employers must therefore apply the rules of the workplace consistently by effecting discipline against all employees accountable for similar misconduct, and also by applying the same sanction for similar infractions. The principle of consistent treatment of employees is referred to as the “parity principle”. It provides that employees who participate in the same or similar wrongdoing, with no distinguishing factors from one case to another, should be penalized in the same way. The foundation of the principle lies in the notion that similar cases must be treated in a similar fashion. It is based on the principle of reasonableness in that fairness in the workplace requires the application of reasonable rules, and not arbitrary or irrational opinions of the employer. Reasonable rules will reflect generality and equality and invariably lead to legal certainty, and a failure by the employer to apply those standards consistently may lead to a finding that the employer acted unfairly in dismissal disputes. In addition to the requirement of consistency, an employer is required to consider a range of other factors before taking the decision to dismiss an employee. These include the gravity of the misconduct; the nature of the work performed by the employee; the circumstances under which the infraction occurred; and the employee’s personal circumstances which may relate to the previous disciplinary record of the employee; his/her length of service and the employee’s personal circumstances. The consideration of these circumstances often leads to a tension between applying the requirement of consistency on the one hand, and the need to take into account the specific circumstances of the employee and circumstances of the misconduct. This comment explores the different approaches adopted by the courts in determining whether or not inconsistent treatment by the employer justifies a finding that the dismissal of an employee was unfair in view of the obligation to take into account the other factors required in the Code. These issues often arise in circumstances where an employee is dismissed by an employer and claims that the employer acted unfairly because other employees were given less severe sanctions for the same or similar misconduct. In deciding the fairness of the matter, the courts have drawn a distinction between individual misconduct and collective misconduct. Historical inconsistency is generally applied in cases of individual misconduct, whilst contemporaneous inconsistency is applied in circumstances of collective misconduct.