These lectures are based on material which was presented in the 2025 Summer school at Fundação Getulio Vargas. The aim of this series is to introduce graduate students with a little background in the field of dynamical systems and network theory to epidemic models. Our goal is to give a succinct and self-contained description of the models
Sarin Suwanpakdee, Anuwat Wiratsudakul, Nattarun Chaisilp
et al.
Abstract The canine distemper virus (CDV) could infect various wildlife species worldwide. The viral infection in large felids directly impacts wildlife conservation. This study aimed to understand better the burden of CDV outbreaks in captive tiger populations in Thailand and a novel discovery of their clinical signs with a history of CDV exposure. We followed up on their infection from June 2016 to October 2020 with laboratory testing and veterinary medical records. The cumulative morbidity and mortality rates were relatively high. Moreover, 50% of the tigers survived at 2 years after infection. Approximately 38% of CDV infections were detected with laryngeal inflammation, which developed into paralysis in almost 50% of cases. Altogether, 50% of tigers with chronic infection developed stridor at 314 days after virus infection [95% CI: 302–320]. Our data indicates that laryngeal paralysis resulted from the CDV infection, potentially affecting the peripheral and central nervous systems. This condition can pose a life-threatening risk to tigers. The virus can spread quickly by contact with bodily excretion among tigers and fomite contamination once it affects a specific population. Implementation of biosecurity measures and vaccination is essential to mitigate the risk of disease spread and infection rates in tiger populations.
Somjit Chaiwattanarungruengpaisan, Metawee Thongdee, Songtham Anuntakarun
et al.
Chlamydia is a known pathogen in both saltwater and freshwater crocodiles. However, the exact species/strain has not been clearly identified. In this study, we successfully cultivated Siamese crocodile Chlamydia in McCoy cells at a temperature of 30°C. Electron microscopy; phylogeny based on nine conserved taxonomically informative markers, on ompA, or on seven housekeeping genes; and whole-genome sequencing and analysis of the isolate confirmed the identity of the isolate as a new member of the genus Chlamydia, a new species that we name Chlamydia crocodili.
Weena Paungpin, Metawee Thongdee, Somjit Chaiwattanarungruengpaisan
et al.
Background and Aim: For a decade, chlamydial and herpesvirus infections have caused significant morbidity and mortality in farmed crocodiles. In September 2017, a total of 160 juvenile freshwater Siamese crocodiles (Crocodylus siamensis) with conjunctivitis/pharyngitis lesions were admitted at the Veterinary Aquatic Animal Research Health Care Unit, Faculty of Veterinary Science, Mahidol University. All crocodiles did not respond well to antibiotics or supportive treatments and died. This study aimed to detect and identify the causative agents associated with conjunctivitis/pharyngitis and fatal outcomes in juvenile farmed Siamese crocodiles. Materials and Methods: A total of 138 pharyngeal and conjunctival swabs and conjunctival scrapes were collected from live crocodiles. All swab and scrape samples were DNA-extracted and amplified by polymerase chain reaction (PCR) using Chlamydiaceae- and herpesvirus-specific primers. Tissue samples (brain, lung, liver, heart, spleen, and intestine) were collected from two representative postmortem animals. All tissue samples were processed for molecular and pathological analyses. Results: PCR examinations identified chlamydial and herpesvirus DNA in 92% (126/138) and 100% (138/138), respectively, of the tested swab and scrape samples. Of those positive samples, 79% (26/33), 67% (4/6), and 98% (97/99) of the pharyngeal swabs, conjunctival swabs, and conjunctival scrapes, respectively, were positive for both chlamydial and herpesvirus DNA. Histopathological examination indicated necrosis and mononuclear cell infiltration in the liver, kidney, and intestine of the affected animals. The intracytoplasmic accumulation of Chlamydia was randomly observed in the examined tissue sample. Moreover, the presence of chlamydial and herpesvirus DNA was also detected in the tissue samples, including the heart, intestine, brain, lung, liver, and spleen, of the affected animals by PCR. Phylogenetic analyses revealed that Chlamydia spp. detected in the juvenile Siamese crocodiles was notably different from other known species in the Chlamydia genus, while the herpesvirus detected in the crocodiles was closely related to crocodyline herpesvirus 1. Conclusion: Based on histopathological and molecular examinations, this report provided the first evidence of coinfection of Chlamydia spp. and crocodyline herpesvirus 1 in juvenile Siamese crocodiles in Thailand.
We are interested in low-dimensional dynamics in an ensemble of coupled nonidentical generalized oscillators on the 3-sphere. The system of governing equations for such an ensemble is referred to as non-Abelian Kuramoto model in the literature. We establish an analogue (or an extension) of the Ott-Antonsen (OA) result for this model.
We study under which conditions systems of coupled oscillators on complex networks display remote synchronization, a situation where pairs of vertices, not necessarily physically linked, but with the same network symmetry, are synchronized.
In a matching pennies game of laboratory experimental economics, with the metric for an instantaneous velocity measurement, we report the first observation of the evolutionary velocity field in the population strategy state space.
We give a pedagogical review of the application of field theoretic and path integral methods to calculate moments of the probability density function of stochastic differential equations perturbatively.
Starting with an initial random network of oscillators with a heterogeneous frequency distribution, its autonomous synchronization ability can be largely improved by appropriately rewiring the links between the elements. Ensembles of synchronization-optimized networks with different connectivities are generated and their statistical properties are studied.
A generalization of Kermack-McKendick model of epidemics to the case of inhomogeneous susceptibility of population is proposed. Some quantitative and qualitative features of epidemic process development in this situation are established.
We show that the spacing distribution between parked cars can be obtained as a solution of certain linear distributional fixed point equation. The results are compared with the data measured on the streets of Hradec Kralove. We also discuss a relation of this results to the random matrix theory.
The two‐stage clonal expansion model is a popular model for carcinogenesis data. One common form of this model is based on the approximate hazard function. In certain situations, this formulation is not appropriate, and the exact hazard should be applied. However, the difficulty of implementing the model based on the exact hazard has deterred many from using it. This paper presents a program implementing the exact hazard model for piecewise constant dosing using SAS, a package that is readily available to most that are interested in this type of analysis. Also, an analysis of the ED01 data is presented using this program, and comparisons are made to an earlier analysis based on the approximate hazard. By allowing for an independent background tumor mechanism, an excellent fit to the bladder tumor incidence data was obtained.