Epidemic spreading with awareness and different time scales in multiplex networks

One of the major issues in theoretical modeling of epidemic spreading is the development of methods to control the transmission of an infectious agent. Human behavior plays a fundamental role in the spreading dynamics and can be used to stop a disease from spreading or to reduce its burden, as individuals aware of the presence of a disease can take measures to reduce their exposure to contagion. In this paper, we propose a mathematical model for the spread of diseases with awareness in complex networks. Unlike previous models, the information is propagated following a generalized Maki-Thompson rumor model. Flexibility on the timescale between information and disease spreading is also included. We verify that the velocity characterizing the diffusion of information awareness greatly influences the disease prevalence. We also show that a reduction in the fraction of unaware individuals does not always imply a decrease of the prevalence, as the relative timescale between disease and awareness spreading plays a crucial role in the systems' dynamics. This result is shown to be independent of the network topology. We finally calculate the epidemic threshold of our model, and show that it does not depend on the relative timescale. Our results provide a new view on how information influence disease spreading and can be used for the development of more efficient methods for disease control

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe

Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies

There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity

Fotoassociação e resfriamento vibracional de moléculas de Rb2 com um laser de alta potência

We have developed a technique to produce, manipulate and trap Rb2 molecules with a single optical beam. This beam is generated by a high-power fiber amplifier (50 W of total output power) in the 1060 to 1070 nm range, which is seeded by two light sources: a sharp-band laser and a broadband superluminescent diode. The laser source is tuned to produce Rb2 molecules from an ultracold 85Rb sample via photoassociation. The broadband spectrum vibrationally cool the molecules by optical pumping. This source is spectrally shaped in order to populate the molecules at the fundamental vibrational state ν = 0. The molecular sample is probed by two-photon ionization, promoted by a pulsed dye laser in the 475 to 480 nm range. By scanning the photoassociation laser frequency, we have obtained a photoassociation spectrum of the ν\' = 138 state of the 0+u potential, confirming previous observations. We have also obtained two vibrational spectra of the molecules by varying the ionization laser frequency, in the presence and absence of the broadband source. The comparison between the two spectra, along with ab-initio data, provides evidences that the molecules are optically pumped to the fundamental vibrational state.Desenvolvemos uma técnica para produzir, manipular e aprisional moléculas de Rb2 com um único feixe óptico. Esse feixe é gerado por um amplificador de alta potência (50 W de potência total de saída) na faixa de 1060 a 1070 nm, que é alimentado por duas fontes de luz: um laser banda estreita e um diodo superluminescente banda larga. O laser é sintonizado para produzir moléculas de Rb2 a partir de uma amostra ultrafria de 85Rb via fotoassociação. O espectro banda larga resfria vibracionalmente as moléculas, por bombeamento óptico. Essa fonte de luz tem seu espectro formatado de modo a deixar as moléculas em seu estado vibracional fundamental ν = 0. A amostra molecular é testada por ionização de dois fótons, promovida por um laser de diodo pulsado na faixa de 475 a 480 nm. Variando a frequência do laser de fotoassociação, obtivemos um espectro de fotoassociação do estado ν\' = 138 do potencial 0+u, confirmando observações anteriores. Obtivemos também dois espectros vibracionais das moléculas variando a frequência do laser de ionização, com e sem a fonte banda larga. Uma comparação entre os dois espectros, junto de dados ab-initio, fornece evidências de que as moléculas são opticamente bombeadas para o estado vibracional fundamental

Modelagem epidêmica com respostas comportamentais dos hospedeiros

Epidemics have always been the cause of significant economic and life losses. Among the multiple developments of science against infectious diseases, mathematical and computational models are increasingly important, especially after the development of complexity and network science. The study and forecasting of epidemics are highly influenced by behaviors of host populations, which are unpredictable and difficult to incorporate. In this thesis, we contribute to the substantial volume of works dedicated to solving this problem. First, we approach the coupling between disease and information spreading on multiplex networks. We propose a rumor-like model for the information and a flexible ratio of time scales between disease and information. We show that increasing the time scale of the information reduces the disease prevalence. We also show that stiflers may cause an increase in both infection and information levels. This problem is then further studied with more general models of asymmetrical interaction between contagion phenomena. We show that our previous results on the time scale depend on the form of interaction between the spreading processes. We also study in more depth these models, numerically describing their transient oscillations and deriving analytical expressions for their steady states and phase transitions. We then switch to systems with host mobility, which is an important ingredient of epidemic spreading. We first develop an individual-based mobility and epidemic model, into which behavioral responses are incorporated as an avoidance of infectious hosts. We show how this reduces the disease spreading in different regimes of our model. In particular, for when mobility evolves much faster than epidemics, we derive a semi-analytical approach to describe the model´s bifurcation diagrams, verifying the existence of a bistable region and relating the dynamics to some metrics of the underlying networks. Finally, we move to larger scales and describe mobility as net flows between homogeneous populations. In this metapopulation scheme, we propose a model for behavioral responses that directly reduce the disease reproduction number. We show that our model can generate different outbreak sizes between subpopulations. Then we use it to compare strategies in which each subpopulation responds independently (locally), or the whole population follows the same response curve (globally). We show which strategy is more effective in different scenarios, for both a random geometric graph and two metapopulations constructed from real data. With the variety of topics that we approached, we hope to contribute significantly to the problem of disease-behavior coupling.Epidemias sempre foram a causa de perdas econômicas e vitais significantes. Entre os múltiplos avanços da ciência contra doenças infecciosas, modelos matemáticos e computacionais são cada vez mais importantes, especialmente após o desenvolvimento da ciência de redes e complexidade. O estudo e previsão de epidemias é muito influenciado por comportamentos da população hospedeira, que são imprevisíveis e difíceis de se incorporar. Nesta tese, contribuímos para o grande volume de trabalhos dedicados a resolver esse problema. Primeiramente, abordamos o acoplamento entre a propagação de doenças e informação em redes multiplex. Propomos um modelo de rumor para a informação, bem como uma razão flexível entre as escalas de tempo da doença e da informação. Mostramos que aumentando a escala temporal da informação se consegue uma redução de casos da doença. Também mostramos que stiflers podem aumentar tanto os níveis da informação quanto da doença. Depois estudamos esse problema mais a fundo com modelos mais gerais de interação assimétrica entre fenômenos de contágio. Mostramos que nossos resultados anteriores com a escala de tempo dependem do formato da interação entre os processos de propagação. Também estudamos esses modelos em mais detalhe, descrevendo numericamente suas oscilações transientes e derivando expressões analíticas para os estados estacionários e transições de fase. Mudamos então para sistemas com mobilidade de hospedeiros. Desenvolvemos um modelo de mobilidade individual, em que respostas comportamentais são incorporadas na forma de esquiva de hospedeiros infectados. Mostramos como isso reduz a propagação da doença em diferentes regimes do modelo. Em particular, para quando a mobilidade progride mais rápido que a doença, derivamos uma abordagem semi-analítica para descrever os diagramas de bifurcação, verificando a existência de uma fase biestável e relacionando a dinâmica com algumas métricas das redes subjacentes. Finalmente, descrevemos a mobilidade como fluxos entre populações homogêneas. Nesse esquema de metapopulação, propomos um modelo para respostas comportamentais que diretamente reduzem o número de reprodução. Mostramos que nosso modelo pode gerar surtos de tamanhos diferentes em cada subpopulação. Então o usamos para comparar estratégias em que cada lugar responde de forma independente (localmente) ou em que toda a população segue a mesma curva (globalmente). Mostramos qual estratégia é mais eficiente em diferentes cenários, tanto para um grafo geométrico aleatório quanto para duas metapopulações de dados reais. Com tal variedade de tópicos explorados, esperamos contribuir para o problema da interação doença-comportamento

A visible-near-infrared light-responsive host-guest pair with nanomolar affinity in water

The discovery of stimuli-responsive high affinity host-guest pairs with potential applications under biologically relevant conditions is a challenging goal. This work reports a high-affinity 1:1 complex formed between cucurbit[8]uril and a water-soluble photochromic diarylethene derivative. It was found that, by confining the open isomer within the cavity of the receptor, a redshift in the absorption spectrum and an enhancement of the photocyclization quantum yield from phi=0.04 to phi=0.32 were induced. This improvement in the photochemical performance enables quantitative photocyclization with visible light that, together with the near-infrared light-induced ring-opening reaction and the 100-fold selectivity for the closed isomer, confirms this as an outstanding light-responsive affinity pair.LAQV-REQUIMTE - Portuguese FCT/MEC [UID/QUI/50006/2019]ERDFEuropean Union (EU) [POCI-01-0145-FEDER-007265]FCT-Foundation for Science and TechnologyPortuguese Foundation for Science and Technology [UID/Multi/04326/2019]operational program CRESC Algarve 2020operational program COMPETE 2020 [EMBRC.PT ALG-01-0145-FEDER-022121]FCT/MEC [RECI/BBB-BQB/0230/2012, PTDC/QUI-COL/32351/2017, PTDC/QUI-QFI/30951/2017, SFRH/BPD/84805/2012]INFUSION project under H2020-MSCA-RISE-2016 [734834]Italian CNR (project PHEEL)Italian CNR (project N-CHEM)info:eu-repo/semantics/publishedVersio

Continuous Loading of Ultracold Ground-State ^{85}Rb_2 Molecules in a Dipole Trap Using a Single Light Beam

International audienc

Crescimento de mudas de abacaxizeiro cv. Vitória durante a aclimatação em função do seu tamanho inicial¹

O abacaxizeiro cv. Vitória é uma nova cultivar lançada recentemente com a relevante característica de ser resistente à fusariose e tem sido distribuída para os produtores através de mudas produzidas in vitro. A aclimatação é fase fundamental para o preparo destas mudas antes do plantio no campo. O uso de mudas de diferentes estádios de crescimento, após a aclimatização, pode interferir na qualidade final das mudas para o plantio no campo, otimizando ou mesmo inviabilizando o sistema de produção. O objetivo deste trabalho foi avaliar as estimativas de crescimento de diferentes tamanhos de mudas produzidas in vitro e aclimatizadas em casa de vegetação, do abacaxizeiro cv. Vitória, durante a fase de aclimatação em canteiros a céu aberto, por um período de 150 dias. Foi utilizado o delineamento experimental em blocos casualizados, em arranjo fatorial 7x5, correspondentes a sete épocas de avaliação (0; 30,; 60; 90; 120; 150 e 161 dias após transplantio para aclimatação) e cinco estádios de desenvolvimento das mudas, representados por E-1, E-2, E-3, E-4 e E-5 (20; 30,; 60; 90 e 150 dias de aclimatização, respectivamente). Os tratamentos foram avaliados em relação ao número de folhas, altura da planta e diâmetro de roseta ao longo do período de aclimatação. Para as condições desse experimento, verifica-se que mudas do estádio 2; 3; 4 e 5podem ser aclimatadas por um período mínimo de 120 dias, sem perda de qualidade para o plantio, e a taxa de crescimento pode ser ajustada a regressões quadráticas de terceiro graus, com elevados índices de determinação (R²)