The Limitations of a Hypothetical All-Variant COVID-19 Vaccine: A Simulation Study.

This paper simulates a hypothetical pan-coronavirus vaccine that confers immediate sterilizing immunity against all SARS-CoV-2 variants. Simulations used a SEIIS (susceptible, exposed, infective, immune, susceptible) spreadsheet model that ran two parallel subpopulations: one that accepted vaccination and another that refused it. The two subpopulations could transmit infections to one another. Using data from the United States (US), the simulated vaccine was tested against limiting factors such as vaccine hesitancy, slow vaccination distribution, and the development of high-transmission variants. The vaccine was often successful at reducing cases, but high-transmission variants and discontinuation of non-pharmaceutical interventions (NPIs) such as masking greatly elevated cases. A puzzling outcome was that if NPIs were discontinued and high-transmission variants became common, the model predicted consistently higher rates of disease than are actually observed in the US in 2024. However, if cumulative exposure to virus antigens increased the duration of immunity or decreased the infectivity of the virus, the model predictions were brought back into a more realistic range. The major finding was that even when a COVID-19 vaccine always produces sterilizing immunity against every SARS-CoV-2 variant, its ability to control the epidemic can be compromised by multiple common conditions.

[Biliary endoprosthesis causing ileal perforation--a case report]. / Perforacja jelita kretego przez przemieszczona endoproteze dróg zólciowych--opis przypadku.

We experienced ileal perforation caused by dislocated biliary endoprosthesis in 59 years old female patient. The endoprosthesis was implanted due to biliary fistula after laparoscopic cholecystectomy 2 years before the perforation. It seems that endoprosthesis dislocation and the perforation were the result of too long stay of endoprosthesis. After the surgical management and the removal of the prosthesis patient was cured. Although ileal perforation caused by dislocated biliary endoprosthesis is rare, clinicians should be aware of the possibility of its occurrence.

Stereovision safety system for identifying workers' presence: results of tests.

This article presents the results of extensive tests of a stereovision safety system performed using real and artificial images. A vision based protective device (VBPD) analyses images from 2 cameras to calculate the position of a worker and moving parts of a machine (e.g., an industrial robot's arm). Experiments show that the stereovision safety system works properly in real time even when subjected to rapid changes in illumination level. Experiments performed with a functional model of an industrial robot indicate that this safety system can be used to detect dangerous situations at workstations equipped with a robot, in human-robot co- operation. Computer-generated artificial images of a workplace simplify and accelerate testing procedures, and make it possible to compare the effectiveness of VBPDs and other protective devices at no additional cost.

Nonlinear model of epidemic spreading in a complex social network.

The epidemic spreading in a human society is a complex process, which can be described on the basis of a nonlinear mathematical model. In such an approach the complex and hierarchical structure of social network (which has implications for the spreading of pathogens and can be treated as a complex network), can be taken into account. In our model each individual has one of the four permitted states: susceptible, infected, infective, unsusceptible or dead. This refers to the SEIR model used in epidemiology. The state of an individual changes in time, depending on the previous state and the interactions with other individuals. The description of the interpersonal contacts is based on the experimental observations of the social relations in the community. It includes spatial localization of the individuals and hierarchical structure of interpersonal interactions. Numerical simulations were performed for different types of epidemics, giving the progress of a spreading process and typical relationships (e.g. range of epidemic in time, the epidemic curve). The spreading process has a complex and spatially chaotic character. The time dependence of the number of infective individuals shows the nonlinear character of the spreading process. We investigate the influence of the preventive vaccinations on the spreading process. In particular, for a critical value of preventively vaccinated individuals the percolation threshold is observed and the epidemic is suppressed.

Effect of continuous quality improvement analysis on the delivery of primary percutaneous revascularization for acute myocardial infarction: a community hospital experience.

As time to reperfusion correlates with outcomes, a door-to-balloon time of 90 +/- 30 min for primary percutaneous coronary revascularization (PCI) for the treatment of acute myocardial infarction has been recently established as a guideline by the ACC/AHA. The purpose of this study is to assess the effects of a continuous quality assurance program designed to expedite primary angioplasty at a community hospital. A database of all primary PCI procedures was created in 1998. Two groups of consecutive patients treated with primary PCI were studied. Group 1 represented patients in the time period between 1 June 1998 to 1 November 1998 and group 2 represented patients in the period between 1 January 2000 and 16 June 2000. Continuous quality assurance analysis was performed. Modifications to the primary angioplasty program were initiated in the latter group. Time intervals to certain treatment landmarks were compared between the groups. Significant decreases in the time intervals from emergency room registration to initial electrocardiogram (8.4 +/- 8.2 vs. 3.7 +/- 19.5 min; P < 0.001), presentation to the catheterization laboratory to arterial access (13.5 +/- 12.9 vs. 11.6 +/- 5.8 min; P < 0.001), and emergency room registration to initial angioplasty balloon inflation (132.0 +/- 69.2 vs. 112 +/- 72.0 min; P < 0.001) were achieved. For the subgroup of patients presenting with diagnostic ST elevation myocardial infarction, a large decrease in the door-to-balloon time interval between group 1 and group 2 was demonstrated (114.15 +/- 9.67 vs. 87.92 +/- 10.93 min; P = NS), resulting in compliance with ACC/AHA guidelines. Continuous quality improvement analysis can expedite care for patients treated by primary PCI in the community hospital setting.

Artificial Neural Networks-Modern Systems for Safety Control.

A short review of the applications of artificial neural networks in different fields of industry with a description of their main properties is made. Such systems have specific properties typical for the human brain, which can decide on the superiority of artificial neural networks over standard control systems. Basic types of such networks as well as their principles of operation and successful applications are described. The application of artificial neural networks in safety engineering is discussed with stress on their special properties, which are necessary in safety critical systems.