Tracing Management and Epidemiological Characteristics of COVID-19 Close Contacts in Cities Around Chengdu, China

Introduction: Close contacts have become a potential threat to the spread of coronavirus disease 2019 (COVID-19). The purpose of this study was to understand the epidemiological characteristics of close contacts of confirmed or suspected cases of COVID-19 in the surrounding cities of Chengdu, China, so as to provide a basis for the management strategy of close contacts.Methods: Close contacts were determined through epidemiological investigation of indicated cases, and relevant information was entered in the “Close Contact Information Management System.” Retrospective data of close contacts from January 22 to May 1, 2020 were collected and organized. Meanwhile, the contact mode, isolation mode, and medical outcome of close contacts were descriptively analyzed.Results: A total of 986 close contacts were effectively traced, with an average age of (36.69 ± 16.86) years old, who were mainly distributed in cities of eastern Chengdu. The frequency of contact was mainly occasional contact, 80.42% of them were relatives and public transportation personnel. Besides, the time of tracking close contacts and feedback was (10.64 ± 5.52) and (7.19 ± 6.11) days, respectively. A total of seven close contacts were converted to confirmed cases.Conclusions: Close contacts of COVID-19 have a risk of invisible infection. Early control of close contacts may be helpful to control the epidemic of COVID-19.

The essence of the mechanism of administrative and legal support of service and combat activity of security forces (on the example of the National Guard of Ukraine)

The article emphasizes that the administrative and legal support of the security forces involves the implementation of the state through a set of legal norms, regulations and means of regulating public relations in the field of security and defense. The narrow definition of administrative and legal support is aimed precisely at the service and combat activities of the security forces. It has been offered to consider administrative and legal maintenance of service and combat activity of security forces as implementation by the state by means of legal norms, instructions and means of streamlining of set of the coordinated and interconnected preventive, protective, protective, mode, isolation-restrictive measures (actions) of bodies, divisions, parts. and individual officials of the security forces, which are carried out in order to ensure the implementation of the tasks facing the security forces in accordance with the law in peacetime and in wartime, as well as crisis situations that threaten national security. The consideration of the mechanism of administrative and legal support of service and combat activity of security forces as a set of legal means, measures and methods by means of which regulation of public relations in the field of service and combat activity of security forces is carried out is substantiated. It has been concluded that the elements of the mechanism of administrative and legal support of the service and combat activities of the security forces include: public relations in the field of providing the service and combat activities of the security forces; authorized subjects of power of the security forces in the field of security and combat activities of the security forces; administrative and legal relations that take place in the process of ensuring the service and combat activities of the security forces; guarantees, measures, means, forms and methods of ensuring the service and combat activities of the security forces. It has been established that a promising area of development of the security and defense sector of the country may be the adoption of a separate Concept of administrative and legal support of combat operations in the field of security and defense (including combat operations of security forces) or other separate regulations.

Parameter identification through mode isolation for reaction–diffusion systems on arbitrary geometries

We present a computational framework for isolating spatial patterns arising in the steady states of reaction–diffusion systems. Such systems have been used to model many natural phenomena in areas such as developmental and cancer biology, cell motility and material science. In many of these applications, often one is interested in identifying parameters which will lead to a particular pattern for a given reaction–diffusion model. To attempt to answer this, we compute eigenpairs of the Laplacian on a variety of domains and use linear stability analysis to determine parameter values for the system that will lead to spatially inhomogeneous steady states whose patterns correspond to particular eigenfunctions. This method has previously been used on domains and surfaces where the eigenvalues and eigenfunctions are found analytically in closed form. Our contribution to this methodology is that we numerically compute eigenpairs on arbitrary domains and surfaces. Here we present examples and demonstrate that mode isolation is straightforward especially for low eigenvalues. Additionally, we show that in some cases the inhomogeneous steady state can be a linear combination of eigenfunctions. Finally, we show an example suggesting that pattern formation is robust on similar surfaces in cases that the surface either has or does not have a boundary.