This work studies the SIS model extended by fractional and fractal derivatives. We obtain explicit solutions for the standard and fractal formulations; for the fractional case, we study numerical solutions. As a real data example, we consider the Brazilian syphilis data from 2011 to 2021. We fit the data by considering the three variations of the model. Our fit suggests a recovery period of 11.6 days and a reproduction ratio ( ) equal to 6.5. By calculating the correlation coefficient ( ) between the real data and the theoretical points, our results suggest that the fractal model presents a higher compared to the standard or fractional case. The fractal formulation is improved when two different fractal orders with distinguishing weights are considered. This modification in the model provides a better description of the data and improves the correlation coefficient.
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September 2023
Research Article|
September 15 2023
Fractal and fractional SIS model for syphilis data
Enrique C. Gabrick
;
Enrique C. Gabrick
a)
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
Graduate Program in Science, State University of Ponta Grossa
, 84030-900 Ponta Grossa, PR, Brazil
a)Author to whom correspondence should be addressed: ecgabrick@gmail.com
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Elaheh Sayari
;
Elaheh Sayari
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
Graduate Program in Science, State University of Ponta Grossa
, 84030-900 Ponta Grossa, PR, Brazil
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Diogo L. M. Souza
;
Diogo L. M. Souza
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
Graduate Program in Science, State University of Ponta Grossa
, 84030-900 Ponta Grossa, PR, Brazil
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Fernando S. Borges
;
Fernando S. Borges
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
2
Department of Physiology and Pharmacology, State University of New York Downstate Health Sciences University
, Brooklyn, New York 11203, USA
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José Trobia
;
José Trobia
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
3
Center for Mathematics, Computation, and Cognition, Federal University of ABC, 09606-045 São Bernardo do Campo, SP
, Brazil
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Ervin K. Lenzi
;
Ervin K. Lenzi
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
Graduate Program in Science, State University of Ponta Grossa
, 84030-900 Ponta Grossa, PR, Brazil
4
Department of Physics, State University of Ponta Grossa
, 84030-900 Ponta Grossa, PR, Brazil
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Antonio M. Batista
Antonio M. Batista
(Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing – original draft, Writing – review & editing)
1
Graduate Program in Science, State University of Ponta Grossa
, 84030-900 Ponta Grossa, PR, Brazil
3
Center for Mathematics, Computation, and Cognition, Federal University of ABC, 09606-045 São Bernardo do Campo, SP
, Brazil
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a)Author to whom correspondence should be addressed: ecgabrick@gmail.com
Chaos 33, 093124 (2023)
Article history
Received:
April 04 2023
Accepted:
August 25 2023
Citation
Enrique C. Gabrick, Elaheh Sayari, Diogo L. M. Souza, Fernando S. Borges, José Trobia, Ervin K. Lenzi, Antonio M. Batista; Fractal and fractional SIS model for syphilis data. Chaos 1 September 2023; 33 (9): 093124. https://doi.org/10.1063/5.0153122
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