MARCOS AMAKU
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Patologia, Faculdade de Medicina - Docente
LIM/01 - Laboratório de Informática Médica, Hospital das Clínicas, Faculdade de Medicina
LIM/01 - Laboratório de Informática Médica, Hospital das Clínicas, Faculdade de Medicina
23 resultados
Resultados de Busca
Agora exibindo 1 - 10 de 23
- The risk of dengue for non-immune foreign visitors to the 2016 summer olympic games in Rio de Janeiro, Brazil(2016) XIMENES, Raphael; AMAKU, Marcos; LOPEZ, Luis Fernandez; COUTINHO, Francisco Antonio Bezerra; BURATTINI, Marcelo Nascimento; GREENHALGH, David; WILDER-SMITH, Annelies; STRUCHINER, Claudio Jose; MASSAD, EduardoBackground: Rio de Janeiro in Brazil will host the Summer Olympic Games in 2016. About 400,000 non-immune foreign tourists are expected to attend the games. As Brazil is the country with the highest number of dengue cases worldwide, concern about the risk of dengue for travelers is justified. Methods: A mathematical model to calculate the risk of developing dengue for foreign tourists attending the Olympic Games in Rio de Janeiro in 2016 is proposed. A system of differential equation models the spread of dengue amongst the resident population and a stochastic approximation is used to assess the risk to tourists. Historical reported dengue time series in Rio de Janeiro for the years 2000-2015 is used to find out the time dependent force of infection, which is then used to estimate the potential risks to a large tourist cohort. The worst outbreak of dengue occurred in 2012 and this and the other years in the history of Dengue in Rio are used to discuss potential risks to tourists amongst visitors to the forthcoming Rio Olympics. Results: The individual risk to be infected by dengue is very much dependent on the ratio asymptomatic/symptomatic considered but independently of this the worst month of August in the period studied in terms of dengue transmission, occurred in 2007. Conclusions: If dengue returns in 2016 with the pattern observed in the worst month of August in history (2007), the expected number of symptomatic and asymptomatic dengue cases among tourists will be 23 and 206 cases, respectively. This worst case scenario would have an incidence of 5.75 (symptomatic) and 51.5 (asymptomatic) per 100,000 individuals.
conferenceObject The risk of infectious diseases introduction into non-infected countries by travelers visiting endemic countries(2015) MASSAD, E.; LOPEZ, L. F.; AMAKU, M.; COUTINHO, F. A. B.; QUAM, M.; BURATTINI, M. N.; STRUCHINER, C. J.; WILDER-SMITH, A.- A Note on the Risk of Infections Invading Unaffected Regions(2018) AMAKU, Marcos; COUTINHO, Francisco Antonio Bezerra; ARMSTRONG, Margaret; MASSAD, EduardoWe present two probabilistic models to estimate the risk of introducing infectious diseases into previously unaffected countries/regions by infective travellers. We analyse two distinct situations, one dealing with a directly transmitted infection (measles in Italy in 2017) and one dealing with a vector-borne infection (Zika virus in Rio de Janeiro, which may happen in the future). To calculate the risk in the first scenario, we used a simple, nonhomogeneous birth process. The second model proposed in this paper provides a way to calculate the probability that local mosquitoes become infected by the arrival of a single infective traveller during his/her infectiousness period. The result of the risk ofmeasles invasion of Italy was of 93% and the result of the risk of Zika virus invasion of Rio de Janeiro was of 22%.
- The risk of urban yellow fever resurgence in Aedes-infested American cities(2018) MASSAD, Eduardo; AMAKU, Marcos; COUTINHO, Francisco Antonio Bezerra; STRUCHINER, Claudio Jose; LOPEZ, Luis Fernandez; COELHO, Giovanini; WILDER-SMITH, Annelies; BURATTINI, Marcelo NascimentoAedes aegypti, historically known as yellow fever (YF) mosquito, transmits a great number of other viruses such as Dengue, West Nile, Chikungunya, Zika, Mayaro and perhaps Oropouche, among others. Well established in Africa and Asia, Aedes mosquitoes are now increasingly invading large parts of the American continent, and hence the risk of urban YF resurgence in the American cities should because of great concern to public health authorities. Although no new urban cycle of YF was reported in the Americas since the end of an Aedes eradication programme in the late 1950s, the high number of non-vaccinated individuals that visit endemic areas, that is, South American jungles where the sylvatic cycle of YF is transmitted by canopy mosquitoes, and return to Aedes-infested urban areas, increases the risk of resurgence of the urban cycle of YF. We present a method to estimate the risk of urban YF resurgence in dengue-endemic cities. This method consists in (1) to estimate the number of Aedes mosquitoes that explains a given dengue outbreak in a given region; (2) calculate the force of infection caused by the introduction of one infective individual per unit area in the endemic area under study; (3) using the above estimates, calculate the probability of at least one autochthonous YF case per unit area produced by one single viraemic traveller per unit area arriving from a YF endemic or epidemic sylvatic region at the city studied. We demonstrate that, provided the relative vector competence, here defined as the capacity to being infected and disseminate the virus, of Ae. aegypti is greater than 0.7 (with respect to dengue), one infected traveller can introduce urban YF in a dengue endemic area.
- On the definition of the time evolution operator for time-independent Hamiltonians in non-relativistic quantum mechanics(2017) AMAKU, Marcos; COUTINHO, Francisco A. B.; TOYAMA, F. MasafumiThe usual definition of the time evolution operator e(-iHt/(h) over bar) = Sigma(infinity)(n-0) 1/h! (-i/(h) over bar Ht)(n), Where H is tha Hamiltonian of the system, as given in almost every book on quantum mechanics, causes problems in some situations. The operators that appear in quantum mechanics are either bounded or unbounded. Unbounded operators are not defined for all the vectors (wave functions) of the Hilbert space of the system; when applied to some states, they give a non-normalizable state. Therefore, if H is an unbounded operator, the definition in terms of the power series expansion does not make sense because it may diverge or result in a non- normalizable wave function. In this article, we explain why this is so and suggest, as an alternative, another definition used by mathematicians. (C) 2017 American Association of Physics Teachers.
- Thermodynamic Potentials and Natural Variables(2020) AMAKU, M.; COUTINHO, F. A. B.; OLIVEIRA, L. N.Abstract Most books on Thermodynamics explain what thermodynamic potentials are and how conveniently they describe the properties of physical systems. Certain books add that, to be useful, the thermodynamic potentials must be expressed in their “natural variables”. Here we show that, given a set of physical variables, an appropriate thermodynamic potential can always be defined, which contains all the thermodynamic information about the system. We adopt various perspectives to discuss this point, which to the best of our knowledge has not been clearly presented in the literature.
- A public health risk assessment for yellow fever vaccination: a model exemplified by an outbreak in the state of Sao Paulo, Brazil(2015) RIBEIRO, Ana Freitas; TENGAN, Cilea; SATO, Helena Keico; SPINOLA, Roberta; MASCHERETTI, Melissa; FRANCA, Ana Cecilia Costa; PORT-CARVALHO, Marcio; PEREIRA, Mariza; SOUZA, Renato Pereira de; AMAKU, Marcos; BURATTINI, Marcelo Nascimento; COUTINHO, Francisco Antonio Bezerra; LOPEZ, Luis Fernandez; MASSAD, EduardoWe propose a method to analyse the 2009 outbreak in the region of Botucatu in the state of Sao Paulo (SP), Brazil, when 28 yellow fever (YF) cases were confirmed, including 11 deaths. At the time of the outbreak, the Secretary of Health of the State of Sao Paulo vaccinated one million people, causing the death of five individuals, an unprecedented number of YF vaccine-induced fatalities. We apply a mathematical model described previously to optimise the proportion of people who should be vaccinated to minimise the total number of deaths. The model was used to calculate the optimum proportion that should be vaccinated in the remaining, vaccine-free regions of SP, considering the risk of vaccine-induced fatalities and the risk of YF outbreaks in these regions.
- Some problems with the use of the Dirac delta function I: What is the value of ∫0∞δ(x)dx?(2021) AMAKU, M.; COUTINHO, F.A.B.; ÉBOLI, O.; MASSAD, E.This is the first of a series of articles dealing with the casual use of distributions made by physicists and engineers. This use is very economical but sometimes leads to embarrassing conclusions that are difficult to justify with rigorous theories of distributions.
- Estimating the probability of dengue virus introduction and secondary autochthonous cases in Europe(2018) MASSAD, Eduardo; AMAKU, Marcos; COUTINHO, Francisco Antonio Bezerra; STRUCHINER, Claudio Jose; BURATTINI, Marcelo Nascimento; KHAN, Kamran; LIU-HELMERSSON, Jing; ROCKLOV, Joacim; KRAEMER, Moritz U. G.; WILDER-SMITH, AnneliesGiven the speed of air travel, diseases even with a short viremia such as dengue can be easily exported to dengue naive areas within 24 hours. We set out to estimate the risk of dengue virus introductions via travelers into Europe and number of secondary autochthonous cases as a result of the introduction. We applied mathematical modeling to estimate the number of dengue-viremic air passengers from 16 dengue-endemic countries to 27 European countries, taking into account the incidence of dengue in the exporting countries, travel volume and the probability of being viremic at the time of travel. Our models estimate a range from zero to 167 air passengers who are dengue-viremic at the time of travel from dengue endemic countries to each of the 27 receiving countries in one year. Germany receives the highest number of imported dengue-viremic air passengers followed by France and the United Kingdom. Our findings estimate 10 autochthonous secondary asymptomatic and symptomatic dengue infections, caused by the expected 124 infected travelers who arrived in Italy in 2012. The risk of onward transmission in Europe is reassuringly low, except where Aedes aegypti is present.
- The effect of the infection within the individual host on its propagation in the population(2018) AZEVEDO, Franciane; AMAKU, Marcos; COUTINHO, Francisco Antonio Bezerra; LOPEZ, Luis Fernandez; MASSAD, EduardoWe consider nested or multiscale models to study the effect of the temporal evolution of the disease within the host in the population dynamics of the disease, for one and two infectious agents. We assumed a coupling between the within-host infection rate and the between-host transmission rate. The age of infection within each individual in a population affects the probability of transmission of the disease to a susceptible host and this will affect the temporal evolution of the disease in the host population. To analyze the infection within the host, we consider bacterial-like and viral-like infections. In the model for two infectious agents, we found that, when strain 2 has a basic reproduction number R-02 greater than the basic reproduction number R-01 of strain 1, strain 2 replaces strain 1 in the population. However, if R-02 > R-01 but the values are closer, the replacement does not occur immediately and both strains can coexist for a long time. We applied the model to a scenario in which patients infected with the hepatitis C virus (HCV) are cleared of HCV when super-infected with the hepatitis A virus (HAV). We compared the time for the replacement of HCV by HAV in the population considering instantaneous and non-instantaneous replacement within the individuals. The model developed can be generalized for more than two infectious agents. (C) 2018 The Authors. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.
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