Addressing a decision problem through a bipolar Pythagorean fuzzy approach: A novel methodology applied to digital marketing.

Decision-making in real-world scenarios faces uncertainty. Fuzzy theory has been a means to represent such uncertainty. In this study, we propose an approach that incorporates bipolarity into multi-criteria decision-making processes applied to digital marketing.

Weibull Regression and Machine Learning Survival Models: Methodology, Comparison, and Application to Biomedical Data Related to Cardiac Surgery.

In this article, we propose a comparative study between two models that can be used by researchers for the analysis of survival data: (i) the Weibull regression model and (ii) the random survival forest (RSF) model. The models are compared considering the error rate, the performance of the model through the Harrell C-index, and the identification of the relevant variables for survival prediction. A statistical analysis of a data set from the Heart Institute of the University of São Paulo, Brazil, has been carried out.

A Two-Stage Location Problem with Order Solved Using a Lagrangian Algorithm and Stochastic Programming for a Potential Use in COVID-19 Vaccination Based on Sensor-Related Data.

Healthcare service centers must be sited in strategic locations that meet the immediate needs of patients. The current situation due to the COVID-19 pandemic makes this problem particularly relevant. Assume that each center corresponds to an assigned place for vaccination and that each center uses one or more vaccine brands/laboratories.

Disjoint and Functional Principal Component Analysis for Infected Cases and Deaths Due to COVID-19 in South American Countries with Sensor-Related Data.

In this paper, we group South American countries based on the number of infected cases and deaths due to COVID-19. The countries considered are: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Paraguay, Uruguay, and Venezuela. The data used are collected from a database of Johns Hopkins University, an institution that is dedicated to sensing and monitoring the evolution of the COVID-19 pandemic.

[Comparison of 4 microscopy techniques for the diagnosis of leptospirosis in wild rodents in a rural area of Valdivia, Chile].

Kidneys of six different species of 93 wild rodents captured in the rural area of Valdivia (Chile) were simultaneously examined for leptospira infection by means of Levaditi silver stain, dark ground microscopy in wet smears, and immunofluorescence and immunoperoxidase techniques using pooled antiserum against hardjo and pomona serovars. Leptospira was shown to be present in 40 (43.0%) rodents.

Ecological aspects of nematode parasites of introduced salmonids from Valdivia river basin, Chile.

Between 1986 and 1987, 666 fishes distributed among the following species introduced in Chile, and from different sectors of the Valdivia river basin (39 degrees 30'-40 degrees 00'S, 73 degrees 30'-71 degrees 45'W), were examined: 348 Salmo trutta, 242 Salmo gairdneri, 24 Cyprinus carpio and 52 Gambusia affinis holbrooki. The presence of Camallanus corderoi and Contracaecum sp. in S.

[Distribution of the infection by Camallanus corderoi (Nemata: Spiruroidea) in different autochthonous hosts and localities of the Valdivia river basin, Chile].

Six hundred and thirty nine autochthonous fish were examined in 1986-1987 in search for Camallanus corderoi infection on different biotopes from Valdivia River basin (between 39 degrees 30'-40 degrees 00'S, 73 degrees 30'-71 degrees 45'' W). Brachigalaxias bullocki, Galaxias maculatus, Galaxias platei, Aplochiton taeniatus, Cheirodon australe, Basilichthys australis and Cauque mauleanum are new hosts for C. corderoi.

[Serological survey of human leptospirosis in a high risk population in Chile].

Two hundred and sixty five subjects with high risk works for leptospirosis were submitted to microscopic agglutination test for leptospira. 122 worked at animal farms, 71 in rice growing fields and 72 in slaughter houses. 30 control subjects were also tested.