ABSTRACT
In this paper, the viscoelastic characterization of biosamples is addressed considering a measuring technique relying on the use of a MEMS techonology-based microgripper. A proper mechanical model is developed for the coupled nonlinear dynamics of the microsystem, composed of the measuring tool and the specimen to be analyzed. The Maxwell liquid drop model and the generalized Maxwell-Wiechert model are considered for the sample, and the identification of the viscoelastic parameters is performed by implementing a genetic algorithm.
Subject(s)
Algorithms , Materials Testing/instrumentation , Mechanical Phenomena , Micro-Electrical-Mechanical Systems , Models, Theoretical , GeneticsABSTRACT
Transmission of Zika virus (ZIKV) in the Americas was first confirmed in May 2015 in northeast Brazil. Brazil has had the highest number of reported ZIKV cases worldwide (more than 200,000 by 24 December 2016) and the most cases associated with microcephaly and other birth defects (2,366 confirmed by 31 December 2016). Since the initial detection of ZIKV in Brazil, more than 45 countries in the Americas have reported local ZIKV transmission, with 24 of these reporting severe ZIKV-associated disease. However, the origin and epidemic history of ZIKV in Brazil and the Americas remain poorly understood, despite the value of this information for interpreting observed trends in reported microcephaly. Here we address this issue by generating 54 complete or partial ZIKV genomes, mostly from Brazil, and reporting data generated by a mobile genomics laboratory that travelled across northeast Brazil in 2016. One sequence represents the earliest confirmed ZIKV infection in Brazil. Analyses of viral genomes with ecological and epidemiological data yield an estimate that ZIKV was present in northeast Brazil by February 2014 and is likely to have disseminated from there, nationally and internationally, before the first detection of ZIKV in the Americas. Estimated dates for the international spread of ZIKV from Brazil indicate the duration of pre-detection cryptic transmission in recipient regions. The role of northeast Brazil in the establishment of ZIKV in the Americas is further supported by geographic analysis of ZIKV transmission potential and by estimates of the basic reproduction number of the virus.
