COVID-19 w Polsce — sekwencja epidemii według modelu SIR

The paper aims to indicate the duration and intensity of the COVID-19 epidemic in Poland. To achieve this goal, the SIR interval model was used. The study was based on data from the Central Statistical Office, Hopkins University, and the Institute of Global Health at the University of Geneva. Based on the analysis results, it was established that the prognosis of the epidemic’s course largely depends on the size of the adopted R virus reproduction coefficient. The higher the coefficient, the more rapid the predicted course of the epidemic, the shorter the duration, and the greater the number of infected. And vice versa: the smaller the coefficient, the milder its course, the longer its duration, and the smaller the number of infected. For this reason, it is important to accurately assess the intensity of the epidemic’s development measured by the virus renewal rate, depending on the nature and intensity of interpersonal contacts. Perhaps in a given country different values of the coefficient for urbanized and rural areas should be used.

Delayed Renewal Process with Uncertain Random Inter-Arrival Times

An uncertain random variable is a tool used to research indeterminacy quantities involving randomness and uncertainty. The concepts of an ’uncertain random process’ and an ’uncertain random renewal process’ have been proposed in order to model the evolution of an uncertain random phenomena. This paper designs a new uncertain random process, called the uncertain random delayed renewal process. It is a special type of uncertain random renewal process, in which the first arrival interval is different from the subsequent arrival interval. We discuss the chance distribution of the uncertain random delayed renewal process. Furthermore, an uncertain random delay renewal theorem is derived, and the chance distribution limit of long-term expected renewal rate of the uncertain random delay renewal system is proved. Then its average uncertain random delay renewal rate is obtained, and it is proved that it is convergent in the chance distribution. Finally, we provide several examples to illustrate the consistency with the existing conclusions.

Assessing the Sustainability of Thryonomys swinderianus Hunting in Ogoni Land

Background: Thryonomys swinderianus is a renewable natural resource and is a major mammal that constitute what is termed bushmeat in Ogoni land. Between July 2017 and June 2018, 10320Kg of Thryonomys swinderianus meat or 2580 animals were obtained from the wild by hunting. The number of animals removed compared to its population as at June 2017 prompted this study. Aim: The aim of the study is to ascertain the sustainability of this level of harvest in Ogoni land. Methods: The Robinson and Redford model of 1991 was used to assess the sustainability of this harvest in this study. The maximum possible production of Thryonomys swinderianus from July 2017 to June 2018 was 3.5/Km² and the proportion of this production to be harvested sustainably is 2.1/Km² or 8.4Kg/Km². The actual harvest within this period was 2.58/Km² or 10.32Kg/Km². Results: The actual harvest of 2.58/Km² is greater than the maximum sustainable yield of 2.1/Km² and as such, the harvest of 2.58 Thryonomys swinderianus per square kilometer per year is not sustainable in Ogoni land. Conclusion: The unsustainable harvest of Thryonomys swinderianus should as a matter of urgent concern be monitored and regulated. Continuation of this rate of removal will diminish the renewal rate and lead to the extinction of Thryonomys swinderianus in the near future.

Reconceptualising Atrial Fibrillation Using Renewal Theory: A Novel Approach to the Assessment of Atrial Fibrillation Dynamics

Despite a century of research, the mechanisms of AF remain unresolved. A universal motif within AF research has been unstable re-entry, but this remains poorly characterised, with competing key conceptual paradigms of multiple wavelets and more driving rotors. Understanding the mechanisms of AF is clinically relevant, especially with regard to treatment and ablation of the more persistent forms of AF. Here, the authors outline the surprising but reproducible finding that unstable re-entrant circuits are born and destroyed at quasi-stationary rates, a finding based on a branch of mathematics known as renewal theory. Renewal theory may be a way to potentially unify the multiple wavelet and rotor theories. The renewal rate constants are potentially attractive because they are temporally stable parameters of a defined probability distribution (the exponential distribution) and can be estimated with precision and accuracy due to the principles of renewal theory. In this perspective review, this new representational architecture for AF is explained and placed into context, and the clinical and mechanistic implications are discussed.

Changes in the productivity of word-formation patterns: Some methodological remarks

Changes in the productivity of word-formation patterns are often investigated using hapax legomena. In this paper, I argue that at least in diachronic investigations of productivity, a measure based on first attestations is a viable alternative to hapax-based measures. I show that such a measure is a more direct proxy to new words than hapax-based measures – it measures what we want to measure, which is not always true for the latter. I present a method that deals with the common problem of varying subcorpus sizes (I suggest we randomly resample the subcorpora up to a predefined size), and to the problem of old words appearing as new at the start of the corpus (I suggest we take an earlier corpus and determine a point in time when almost all old words have registered). Armed with these instruments, we can determine the ratio of new types to existing types for a time span, which can be regarded as the renewal rate of the respective category.

A Study of the Copyright Renewal Rate for Maps

This study examines the copyright renewal of maps published in the United States from 1923 to 1950 and compares the results with a recent study of copyright renewals for books. Results indicate that, while the average copyright renewal rate for maps appears similar to that of books, the average was skewed higher by a single publisher whose renewal rate was much higher than average. With the data from that publisher excluded, the average copyright renewal rate dropped to 10% meaning that a significant number of maps copyrighted in the U.S. in the first half of the 20th century are probably in the public domain due to lack of copyright renewal.