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Recent empirical evidence suggests that the transmission coefficient in susceptible-exposed-infected-removed-like (SEIR-like) models evolves with time, presenting random patterns, and some stylized facts, such as mean-reversion and jumps. To address such observations we propose the use of jump-diffusion stochastic processes to parameterize the transmission coefficient in an SEIR-like model that accounts for death and time-dependent parameters. We provide a detailed theoretical analysis of the proposed model proving the existence and uniqueness of solutions as well as studying its asymptotic behavior. We also compare the proposed model with some variations possibly including jumps. The forecast performance of the considered models, using reported COVID-19 infections from New York City, is then tested in different scenarios. Despite the simplicity of the epidemiological model, by considering stochastic transmission, the forecasted scenarios were fairly accurate.

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We developed a simple linear stochastic model for Dalbulus maidis dependent exclusively on temperature, whose parameters were determined from published field and laboratory studies performed at different temperatures. This model takes into account the principal stages and events of the life cycle of this pest, which is vector of maize diseases. We implemented the effect of distributed delays or Linear Chain Trick (LCT) considering a fixed number of sub-stages for egg and nymph stages of Dalbulus maidis in order to accurately represent what is observed in nature. A sensitivity analysis allows us to observe that the speed of the dynamics is sensitive to changes in the development rates, but not to the longevity of each stage or the fecundity, which almost exclusively affect insect abundance. We used our model to study its predictive and explanatory capacity considering a published experiment as a case study. Although the simulation results show a behavior qualitatively equivalent to that observed in the experimental results it is not possible to explain accurately the magnitude, nor the times in which the maximum abundances of second-generation nymphs and adults are reached. Therefore, we evaluated three possible scenarios for the insect that allow us to glimpse some of the advantages of having a computational model in order to find out what processes, taken into account in the model, may explain the differences observed between published experimental results and model results. The three proposed scenarios, based on variations in the parameterized rates of the model, can satisfactorily explain the experimental observations. We observed that in order to better simulate the experimental results it is not necessary to modify fecundity or mortality rates. However, it is necessary to accelerate the average development rates of our model by 20 to 40 %, compatible with extreme values of the rates close to the upper edges of the confidence bands of our parameterization rate curves, according to insects with faster development rates already reported in literature.

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Despite the important roles that marine sponges play in ecosystem functioning and structuring, little is known about how the sponge holobiont responds to local anthropogenic impacts. Here we assess the influence of an impacted environment (Praia Preta) on the microbial community associated with the endemic sponge Aplysina caissara in comparison to a less-impacted area (Praia do Guaecá) from the coast of São Paulo state (Brazil, southwestern Atlantic coast). We hypothesized that the local anthropogenic impacts will change the microbiome of A. caissara and that the community assembly will be driven by a different process (i.e. deterministic versus stochastic) under distinct levels of impact. The microbiome at the amplicon sequence variants level was found to be statistically distinct between sponges from the different sites, and this was also seen for the microbial communities of the surrounding seawater and sediments. Microbial communities of A. caissara from both sites were found to be assembled by deterministic processes, even though the sites presented distinct anthropogenic impacts, showing a pivotal role of the sponge host in selecting its own microbiome. Overall, this study revealed that local anthropogenic impacts altered the microbiome of A. caissara; however, assembly processes are largely determined by the sponge host.

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The thermal conductance of a one-dimensional classical inertial Heisenberg model of linear size L is computed, considering the first and last particles in thermal contact with heat baths at higher and lower temperatures, Th and Tl (Th>Tl), respectively. These particles at the extremities of the chain are subjected to standard Langevin dynamics, whereas all remaining rotators (i=2,⋯,L-1) interact by means of nearest-neighbor ferromagnetic couplings and evolve in time following their own equations of motion, being investigated numerically through molecular-dynamics numerical simulations. Fourier's law for the heat flux is verified numerically, with the thermal conductivity becoming independent of the lattice size in the limit L→∞, scaling with the temperature, as κ(T)∼T-2.25, where T=(Th+Tl)/2. Moreover, the thermal conductance, σ(L,T)≡κ(T)/L, is well-fitted by a function, which is typical of nonextensive statistical mechanics, according to σ(L,T)=Aexpq(-Bxη), where A and B are constants, x=L0.475T, q=2.28±0.04, and η=2.88±0.04.

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The COVID-19 pandemic has imposed several dilemmas for managers in the public sector, with school reopening being among the most complex decisions. The present article presents a microsimulation model of the pandemic course considering various scenarios within the confines of a classroom in the city of Belo Horizonte, Brazil. For that, a susceptible-infectious-recovered (SIR) model was integrated with a random graph model, associating epidemiological characteristics with sociometric and sociodemographic factors. Social contact rates projected for Brazil in the European POLYMOD project were adapted for the city of Belo Horizonte to simulate the number of contacts among individuals considering a Poisson distribution. The simulation used as reference a group of 20 students and their families. The projected scenarios discriminated three age groups with their respective rate of daily social contacts: 0 to 5 years (0.01), 6 a 14 years (1.80), and 15 to 19 years (0.20). The simulations showed clear differences between these age groups, depending on the initial number of infected individuals and on the use or not of face masks in the school. The results confirm that the absence of adequate mitigation measures entails a considerable increase in transmission in the school setting.

La pandemia de COVID-19 ha creado una serie de dilemas para los administradores públicos, que ha hecho de la reapertura de las escuelas una de las decisiones más complejas. En el presente artículo se presenta una microsimulación del curso de la pandemia, en la cual se analizan varias situaciones hipotéticas dentro de los límites de un salón de clases en la ciudad de Belo Horizonte (Brasil). Se utilizó un modelo de personassusceptibles, infectadas y recuperadas (SIR) integrado a un modelo de gráficos aleatorios, dentro del cual se asociaron lascaracterísticas epidemiológicas a factores sociométricos y sociodemográficos. Se utilizaron las tasas de contactos sociales previstas para Brasil por el proyecto europeo POLYMOD y adaptadas a la ciudad de Belo Horizonte con el fin de simular el número de contactos entre las personas con una distribución de Poisson. Para la simulación se tomó como referencia un grupo de 20 alumnos y sus familias. En las situaciones hipotéticas proyectadas se distinguieron tres grupos etarios con sus respectivas tasas diarias de contactos sociales: de 0 a 5 años (0,01), de 6 a 14 años (1,80) y de 15 a 19 años (0,20). Las simulaciones demostraron que hay claras diferencias en los grupos etarios analizados, según el número inicial de personas infectadas y el uso o la falta de uso de mascarilla en el ambiente escolar. Los resultados confirman que la falta de medidas adecuadas de mitigación eleva de forma considerable el riesgo de contagio en la comunidad escolar.

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Abstract The use of devices that produce stochastic whole-body vibration as a resource for rehabilitation and training programs has been founded on the theory of stochastic resonance. However, the prescription of rehabilitation and training programs must be preceded by the verification of imposed-vibration magnitude and of how it can be affected by the presence of an individual on the devices. The aim of this research was to characterize and analyze the effect of an individual's mass on the vibratory stimulus provided by stochastic whole-body vibration (SWBV) devices. The sample consisted of 30 repetitions for each one of the 6 vibration levels of the SWBV device (level 02, 04, 06, 08, 10 and 12), performed in two experimental situations (Without Load; Load [70Kg]; ≈ 35 kg on the right and left surfaces of the platform). For the antero-posterior, latero-lateral, and vertical directions, all variables showed significant differences between treatments, levels and interaction between experimental factors (p<.05), except for the Disp variable between treatments (p=.075). To measure vibration magnitude, a triaxial accelerometer was attached at the center of the board of one of the platform surfaces. Load interferes with parameters of vibration imposed by SWBV platforms, increasing ARMS and APEAK in the latero-lateral and antero-posterior directions, reducing these same parameters in the vertical direction.

Resumo O uso de dispositivos que produzem vibração estocástica de corpo inteiro como recurso para programas de reabilitação e treinamento foi fundamentado na teoria da ressonância estocástica. Entretanto, a prescrição de programas de reabilitação e treinamento deve ser precedida da verificação da magnitude da vibração imposta e de como ela pode ser afetada pela presença de um indivíduo nos dispositivos. O objetivo deste estudo foi caracterizar e analisar o efeito da massa do indivíduo sobre o estímulo vibratório proporcionado por dispositivos de vibração estocástica de corpo inteiro. A amostra consistiu em 30 repetições para cada um dos 6 níveis de vibração de um dispositivo de vibração estocástica de corpo inteiro (nível 02, 04, 06, 08, 10 e 12), realizados em duas situações experimentais (Sem carga e Carga [70Kg], 35 kg nas superfícies direita e esquerda da plataforma). Para medir a magnitude da vibração, um acelerômetro triaxial foi fixado ao centro do assoalho de uma das superfícies da plataforma. Para os eixos ântero-posterior, látero-lateral e vertical, todas as variáveis mostraram diferenças entre tratamentos, níveis e interação entre fatores experimentais (p<.05), exceto para a variável de deslocamento pico - a - pico (Disp) entre tratamentos (p=.075). A carga interfere com parâmetros de vibração impostos sobre as plataformas de vibração estocástica de corpo inteiro, aumentando a aceleração média (ARMS) e de pico (APEAK) nas direções látero-lateral e ântero-posterior, reduzindo estes mesmos parâmetros na direção vertical.

RESUMO

RESUMO A pandemia da COVID-19 tem levantado uma série de dilemas para os gestores públicos, sendo a reabertura das escolas uma das decisões mais complexas. O presente artigo apresenta uma microssimulação do curso da pandemia considerando vários cenários dentro dos limites de uma sala de aula na cidade de Belo Horizonte, Brasil. Utilizou-se um modelo de suscetíveis-infectados-recuperados (SIR) integrado a um modelo de grafos aleatórios, associando características epidemiológicas a fatores sociométricos e sociodemográficos. Foram utilizadas as taxas de contatos sociais projetadas para o Brasil pelo projeto europeu POLYMOD e adaptadas para a cidade de Belo Horizonte para simular o número de contatos entre os indivíduos seguindo uma distribuição de Poisson. A simulação tomou como referência 20 alunos e suas famílias. Os cenários projetados discriminaram três faixas etárias com as suas respectivas taxas diárias de contatos sociais: 0 a 5 anos (0,01), 6 a 14 anos (1,80) e 15 a 19 anos (0,20). As simulações demonstraram diferenças claras para os grupos etários considerados, dependendo do número de infectados iniciais e do uso ou não de máscara no espaço escolar. Os resultados confirmam que a ausência de medidas adequadas de mitigação eleva de forma considerável o risco de contágio na comunidade escolar.

ABSTRACT The COVID-19 pandemic has imposed several dilemmas for managers in the public sector, with school reopening being among the most complex decisions. The present article presents a microsimulation model of the pandemic course considering various scenarios within the confines of a classroom in the city of Belo Horizonte, Brazil. For that, a susceptible-infectious-recovered (SIR) model was integrated with a random graph model, associating epidemiological characteristics with sociometric and sociodemographic factors. Social contact rates projected for Brazil in the European POLYMOD project were adapted for the city of Belo Horizonte to simulate the number of contacts among individuals considering a Poisson distribution. The simulation used as reference a group of 20 students and their families. The projected scenarios discriminated three age groups with their respective rate of daily social contacts: 0 to 5 years (0.01), 6 a 14 years (1.80), and 15 to 19 years (0.20). The simulations showed clear differences between these age groups, depending on the initial number of infected individuals and on the use or not of face masks in the school. The results confirm that the absence of adequate mitigation measures entails a considerable increase in transmission in the school setting.

RESUMEN La pandemia de COVID-19 ha creado una serie de dilemas para los administradores públicos, que ha hecho de la reapertura de las escuelas una de las decisiones más complejas. En el presente artículo se presenta una microsimulación del curso de la pandemia, en la cual se analizan varias situaciones hipotéticas dentro de los límites de un salón de clases en la ciudad de Belo Horizonte (Brasil). Se utilizó un modelo de personassusceptibles, infectadas y recuperadas (SIR) integrado a un modelo de gráficos aleatorios, dentro del cual se asociaron lascaracterísticas epidemiológicas a factores sociométricos y sociodemográficos. Se utilizaron las tasas de contactos sociales previstas para Brasil por el proyecto europeo POLYMOD y adaptadas a la ciudad de Belo Horizonte con el fin de simular el número de contactos entre las personas con una distribución de Poisson. Para la simulación se tomó como referencia un grupo de 20 alumnos y sus familias. En las situaciones hipotéticas proyectadas se distinguieron tres grupos etarios con sus respectivas tasas diarias de contactos sociales: de 0 a 5 años (0,01), de 6 a 14 años (1,80) y de 15 a 19 años (0,20). Las simulaciones demostraron que hay claras diferencias en los grupos etarios analizados, según el número inicial de personas infectadas y el uso o la falta de uso de mascarilla en el ambiente escolar. Los resultados confirman que la falta de medidas adecuadas de mitigación eleva de forma considerable el riesgo de contagio en la comunidad escolar.

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The short-term economic consequences of the critical measures employed to curb the transmission of Covid-19 are all too familiar, but the consequences of isolation and loneliness resulting from those measures on the mental well-being of the population and their ensuing long-term economic effects are largely unknown. Here we offer a stochastic agent-based model to investigate social restriction measures in a community where the feelings of loneliness of the agents dwindle when they are socializing and grow when they are alone. In addition, the intensity of those feelings, which are measured by a real variable that we term degree of loneliness, determines whether the agent will seek social contact or not. We find that decrease of the number, quality or duration of social contacts lead the community to enter a regime of burnout in which the degree of loneliness diverges, although the number of lonely agents at a given moment amounts to only a fraction of the total population. This regime of mental breakdown is separated from the healthy regime, where the degree of loneliness is finite, by a continuous phase transition. We show that the community dynamics is described extremely well by a simple mean-field theory so our conclusions can be easily verified for different scenarios and parameter settings. The appearance of the burnout regime illustrates neatly the side effects of social distancing, which give to many of us the choice between physical infection and mental breakdown.

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The shocking severity of the Covid-19 pandemic has woken up an unprecedented interest and accelerated effort of the scientific community to model and forecast epidemic spreading to find ways to control it regionally and between regions. Here we present a model that in addition to describing the dynamics of epidemic spreading with the traditional compartmental approach takes into account the social behaviour of the population distributed over a geographical region. The region to be modelled is defined as a two-dimensional grid of cells, in which each cell is weighted with the population density. In each cell a compartmental SEIRS system of delay difference equations is used to simulate the local dynamics of the disease. The infections between cells are modelled by a network of connections, which could be terrestrial, between neighbouring cells, or long range, between cities by air, road or train traffic. In addition, since people make trips without apparent reason, noise is considered to account for them to carry contagion between two randomly chosen distant cells. Hence, there is a clear separation of the parameters related to the biological characteristics of the disease from the ones that represent the spatial spread of infections due to social behaviour. We demonstrate that these parameters provide sufficient information to trace the evolution of the pandemic in different situations. In order to show the predictive power of this kind of approach we have chosen three, in a number of ways different countries, Mexico, Finland and Iceland, in which the pandemics have followed different dynamic paths. Furthermore we find that our model seems quite capable of reproducing the path of the pandemic for months with few initial data. Unlike similar models, our model shows the emergence of multiple waves in the case when the disease becomes endemic.

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Teorias sobre fenômenos psicológicos frequentemente fazem referência a processos que não são diretamente observáveis (processos latentes). Tradicionalmente, no entanto, a investigação desses fenômenos é feita de forma indireta aos processos latentes. O objetivo deste artigo é introduzir os conceitos fundamentais de modelagem multinomial. Aqui mostramos como modelos de processos latentes são derivados de modelos puramente descritivos através da redução do espaço de parâmetros motivada por uma ou mais teorias psicológicas. Os resultados são os modelos multinomiais que fornecem medidas simples de processos psicológicos (probabilidades) e que podem ser quantitativamente testados com dados reais. O uso de modelagem multinomial permite a análise direta dos efeitos de variáveis independentes nos próprios processos latentes que controlam o desempenho em uma ou mais tarefas experimentais, assim, facilitando o teste de predições e explicações teóricas sobre fenômenos psicológicos.

Theories about psychological phenomena often refer to unobservable processes (latent processes). Traditionally, however, the psychological investigation of these phenomena is done indirectly to the latent processes themselves. The objective of this article is to introduce fundamental concepts about multinomial modeling. Here we show that latent processes models are derived from purely descriptive models by reducing the parameter space according to one or more psychological theories. The result is multinomial models that deliver simple measures of psychological processes (probabilities) and that can be tested quantitatively with real data. The use of multinomial modeling allows direct analysis of the effects of independent variables on the latent processes that control performance on one or more experimental tasks, thus making it easier to test theoretical predictions and explanations about psychological phenomena.

Teorías sobre fenómenos psicológicos a menudo se refieren a procesos que no son directamente observables (procesos latentes). Sin embargo, la investigación de estos fenómenos se realiza tradicionalmente de manera indirecta con respecto a los procesos latentes. El propósito de este artículo es presentar los conceptos fundamentales del modelado multinomial. Aquí mostramos cómo los modelos de procesos latentes se derivan de modelos puramente descriptivos al reducir el espacio de parámetros motivado por una o más teorías psicológicas. El resultado son modelos multinomiales que proporcionan medidas simples de procesos psicológicos (probabilidades) y que pueden probarse cuantitativamente con datos reales. El uso de modelos multinomiales permite el análisis directo de los efectos de variables independientes en los procesos latentes que controlan el rendimiento en una o más tareas experimentales, lo que facilita la prueba de predicciones y explicaciones teóricas sobre fenómenos psicológicos.

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Many works in the literature are in favour of the universality of power-laws. However, more recently, a significant amount of research has exposed more subtle details about this subject. In this paper we present two generalisations that aim to solve these possible antagonistic conceptions in a mathematical framework. The first generalisation allows us to show that a vast range of power-laws can be produced through multiplicative process (for example through a single positive feedback mechanism). The second generalisation shows, by solving Lambert's transcendental equations, that the space of solutions where the Pareto distribution is equal to the distribution produced by the power multiplicative transformation (for a number of input distributions) is infinite.

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We propose a minimalist stochastic population model of maize, focused on the description of the maize vegetative stages (seedlings with different number of leaves) involved in the propagation of vector-borne diseases. This model was parameterized from laboratory and field experiments and from observational field studies for multiple hybrids and different weather and soil conditions, taking into account only temperature as input variable. We propose three different submodels to estimate the distribution of the Final Leaf Number NFLN in the plants and to estimate the tassel initiation probability. The first submodel (submodel A), with a fixed NFLN, is adaptable to any particular hybrid, the second and third submodels allow to simulate plants with an empirical NFLN distribution according to bibliographic averages (submodel B) or according to a Poisson Process (submodel C). The three submodels are able to describe the temporal development of populations and events. A good agreement is observed between the development times predicted by the model and the values obtained from laboratory experiments at constant temperature, field experiments carried out in Brazil and Australia and observational studies performed in Argentina. This model may be improved and coupled to leaf growth models and leaf area estimation models to be able to estimate not only the temporal development of populations and events but also the temporal development of the leaf area by plant, which is believed to be related to the carrying capacity of maize specialists insects, vectors of maize diseases.

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By means of a probabilistic mathematical model, we bring into discussion the origin of life as a stochastic process. We consider only the chance of information emergence in the proteome and genome under the ideal thermodynamic and chemical conditions. For a more realistic model, we used, as a parameter, the information amount in Nanoarchaeum equitans genome, the simplest known nowadays, as the equivalent to the first living cell that could have emerged in primitive Earth. We estimated the probability of information emergence by chance as about 10-500000. Considering the necessary ideal conditions for information emergence, the probability of the origin of life would be even smaller.(AU)

Através de um modelo probabilísticomatetmático, nós trazemos à discussão a origem da vida como um processo estocástico. Nós consideramossomente a chance da emergência da informação do proteoma e do genoma sob condições termodinâmicase químicas ideais. Para um modelo realístico, nós usamos, como parâmetro, o conteúdo informacional nogenoma do Nanoarchaeum equitans, a mais simples conhecida, como o equivalente a primeira célula viva quepoderia ter emergido na terra primitiva. Nós estimamos a probabilidade da emergência como sendo próximada 10-500.000. Considerando as condições ideais para emergência da informação, a probabilidade da origem da vida deveria ser ainda menor.(AU)

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By means of a probabilistic mathematical model, we bring into discussion the origin of life as a stochastic process. We consider only the chance of information emergence in the proteome and genome under the ideal thermodynamic and chemical conditions. For a more realistic model, we used, as a parameter, the information amount in Nanoarchaeum equitans genome, the simplest known nowadays, as the equivalent to the first living cell that could have emerged in primitive Earth. We estimated the probability of information emergence by chance as about 10-500000. Considering the necessary ideal conditions for information emergence, the probability of the origin of life would be even smaller.

Através de um modelo probabilísticomatetmático, nós trazemos à discussão a origem da vida como um processo estocástico. Nós consideramossomente a chance da emergência da informação do proteoma e do genoma sob condições termodinâmicase químicas ideais. Para um modelo realístico, nós usamos, como parâmetro, o conteúdo informacional nogenoma do Nanoarchaeum equitans, a mais simples conhecida, como o equivalente a primeira célula viva quepoderia ter emergido na terra primitiva. Nós estimamos a probabilidade da emergência como sendo próximada 10-500.000. Considerando as condições ideais para emergência da informação, a probabilidade da origem da vida deveria ser ainda menor.

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The effects of randomness, an unavoidable feature of intracellular environments, are observed at higher hierarchical levels of living matter organization, such as cells, tissues, and organisms. Additionally, the many compounds interacting as a well-orchestrated network of reactions increase the difficulties of assessing these systems using only experiments. This limitation indicates that elucidation of the dynamics of biological systems is a complex task that will benefit from the establishment of principles to help describe, categorize, and predict the behavior of these systems. The theoretical machinery already available, or ones to be discovered to help solve biological problems, might play an important role in these processes. Here, we demonstrate the application of theoretical tools by discussing some biological problems that we have approached mathematically: fluctuations in gene expression and cell proliferation in the context of loss of contact inhibition. We discuss the methods that have been employed to provide the reader with a biologically motivated phenomenological perspective of the use of theoretical methods. Finally, we end this review with a discussion of new research perspectives motivated by our results.

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In this paper we propose a model for the formation of paths in Argentine ants when foraging in an empty arena. Based on experimental observations, we provide a distribution for the random change in direction that they approximately undergo while foraging as a mixture of a Gaussian and a Pareto distribution. By following the principles described in previous work, we consider persistence and reinforcement to create a model for the motion of ants in the plane. Numerical simulations based on this model lead to the formation of branched ant-trails analogous to those observed experimentally.

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Context: Drink tests constitute an inexpensive and non-invasive tool, which has been proposed to discriminate individuals with altered fluid intake, as dyspeptics. However, their use in everyday clinical practice is still limited as standardization still lacks. Objective: To perform a direct, paired comparison between the water and the nutrient drink test in normal volunteers. Methods: Thirty eight normal volunteers (19 males, 19 females, mean age 24.4 ± 0.4 years) underwent drink test with water and nutrient (Nutridrink) within 7-10 days. Both tests included a loading (consumption of 100 mL/min for water and 15 mL/min for Nutridrink for the longest possible period of time) and a recuperation phase (observation after cessation of fluid intake), being separated by the maximal saturation point. During phases, satiety, fullness, discomfort, bloating, belching, nausea, pain and burning sensation (epigastric and thoracic) were recorded using a 0-100 visual analogue scale score (VAS). For the purpose of configuration, four variables were considered: time (t), VAS score (V), VAS slope (S) for a given time period, and probability of participation (Q) at a given timepoint. Results: The loading phase lasted for 11.6 ± 1.7 min in water (total VAS: 879 ± 123, total VAS slope 72.6 ± 10.9 min-1) and 93.3 ± 18.4 min in Nutridrink test (total VAS: 1462 ± 411, total VAS slope 15.9 ± 3.2 min-1); P<0.001. The mean ingested volume recorded was 1155 ± 164 mL for water and 1399 ± 276 mL for nutrient; P = 0.076. Cessation of fluid intake was mainly attributed to fullness (76.3 percent) in water and satiety (69.2 percent) in Nutridrink test. Nausea was recorded only in Nutridrink test (15.4 percent). No volunteer reported substantial, persistent pain or burning sensation. The recuperation phase lasted 63.6 ± 7.8 min in water (total VAS: 278 ± 75, total VAS slope 3.97 ± 0.95 min-1) and 123.2 ± 17.5 min in Nutridrink test (total VAS: 841 ± 126, total VAS slope...

Contexto: Os testes de bebidas se constituem em meios baratos e não-invasivos propostos para distinguir diferenças de volume ingeridos por indivíduos, como os dispépticos, por exemplo. Entretanto, seu uso na prática clínica ainda é limitado pela falta de parâmetros lineares. Objetivos: Realizar comparação entre ingestão de água e solução de nutrientes em voluntários, utilizando-se o teste de bebidas e escala analógica visual. Métodos: Trinta e oito voluntários (19 homens, 19 mulheres, com média de idade: 24,4 ± 0,4 anos) submeteram-se a teste de bebidas com água e Nutridrink, em intervalo de 7 a 10 dias. Ambos os testes incluíram a fase de ingestão (consumo de 100 mL/min para água e 15 mL/min para o Nutridrink, pelo maior tempo possível), e pela fase de recuperação (observação após o término da ingestão), separados pelo máximo ponto de saturação. Durante as fases observou-se a saciedade, a plenitude, o desconforto, a eructação, os borborigmos, a náusea, a queimação epigástrica ou torácica e a dor, que foram anotadas utilizando-se um escore de escala analógica visual (EAV) variando entre 0-100. Para este propósito quatro variáveis foram consideradas: tempo (T), escore EAV (V), e curva EAV (S), para o período de tempo e a probabilidade de participação a um tempo determinado (Q). Resultados: O tempo de ingestão durou 11,6 ± 1,7 min para a água (total EAV: 879 ±123, total S: 72,6 ± 10,9 min-1) e 93,3 ± 18,4 min para o Nutridrink (total EAV: 1462 ± 411, total S: 15,9 ± 3,2 min-1); P<0.001. O volume médio ingerido foi de 1155 ± 164 mL para água e 1399 ± 276 mL para o nutriente; P = 0.076. A parada de ingestão do líquido foi atribuída à sensação de plenitude em 76,3 por cento para a água e a saciedade em 69,2 por cento para o Nutridrink. Náusea foi relatada em 15,4 por cento somente para o teste de nutriente. Nenhum voluntário reportou dor substancial persistente ou sensação de queimação. A fase de recuperação durou 63,6 ± 7,8 min para a água...

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Behavioral observations suggest that multiple sensory elements can be maintained for a short time, forming a perceptual buffer which fades after a few hundred milliseconds. Only a subset of this perceptual buffer can be accessed under top-down control and broadcasted to working memory and consciousness. In turn, single-cell studies in awake-behaving monkeys have identified two distinct waves of response to a sensory stimulus: a first transient response largely determined by stimulus properties and a second wave dependent on behavioral relevance, context and learning. Here we propose a simple biophysical scheme which bridges these observations and establishes concrete predictions for neurophsyiological experiments in which the temporal interval between stimulus presentation and top-down allocation is controlled experimentally. Inspired in single-cell observations, the model involves a first transient response and a second stage of amplification and retrieval, which are implemented biophysically by distinct operational modes of the same circuit, regulated by external currents. We explicitly investigated the neuronal dynamics, the memory trace of a presented stimulus and the probability of correct retrieval, when these two stages were bracketed by a temporal gap. The model predicts correctly the dependence of performance with response times in interference experiments suggesting that sensory buffering does not require a specific dedicated mechanism and establishing a direct link between biophysical manipulations and behavioral observations leading to concrete predictions.