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1.
Zhejiang Da Xue Xue Bao Yi Xue Ban ; 50(1): 68-73, 2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-34117853

RESUMO

:To predict the epidemiological trend of coronavirus disease 2019 (COVID-19) by mathematical modeling based on the population mobility and the epidemic prevention and control measures. : As of February 8,2020,the information of 151 confirmed cases in Yueqing,Zhejiang province were obtained,including patients' infection process,population mobility between Yueqing and Wuhan,etc. To simulate and predict the development trend of COVID-19 in Yueqing, the study established two-stage mathematical models,integrating the population mobility data with the date of symptom appearance of confirmed cases and the transmission dynamics of imported and local cases. : It was found that in the early stage of the pandemic,the number of daily imported cases from Wuhan (using the date of symptom appearance) was positively associated with the number of population travelling from Wuhan to Yueqing on the same day and 6 and 9 days before that. The study predicted that the final outbreak size in Yueqing would be 170 according to the number of imported cases estimated by consulting the population number travelling from Wuhan to Yueqing and the susceptible-exposed-infectious-recovered (SEIR) model; while the number would be 165 if using the reported daily number of imported cases. These estimates were close to the 170,the actual monitoring number of cases in Yueqing as of April 27,2020. : The two-stage modeling approach used in this study can accurately predict COVID-19 epidemiological trend.


Assuntos
COVID-19 , China/epidemiologia , Surtos de Doenças , Humanos , Modelos Teóricos , Pandemias , SARS-CoV-2
2.
Int J Mol Sci ; 22(9)2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-34068601

RESUMO

Cold atmospheric plasma (CAP) and plasma-treated liquids (PTLs) have recently become a promising option for cancer treatment, but the underlying mechanisms of the anti-cancer effect are still to a large extent unknown. Although hydrogen peroxide (H2O2) has been recognized as the major anti-cancer agent of PTL and may enable selectivity in a certain concentration regime, the co-existence of nitrite can create a synergistic effect. We develop a mathematical model to describe the key species and features of the cellular response toward PTL. From the numerical solutions, we define a number of dependent variables, which represent feasible measures to quantify cell susceptibility in terms of the H2O2 membrane diffusion rate constant and the intracellular catalase concentration. For each of these dependent variables, we investigate the regimes of selective versus non-selective, and of synergistic versus non-synergistic effect to evaluate their potential role as a measure of cell susceptibility. Our results suggest that the maximal intracellular H2O2 concentration, which in the selective regime is almost four times greater for the most susceptible cells compared to the most resistant cells, could be used to quantify the cell susceptibility toward exogenous H2O2. We believe our theoretical approach brings novelty to the field of plasma oncology, and more broadly, to the field of redox biology, by proposing new ways to quantify the selective and synergistic anti-cancer effect of PTL in terms of inherent cell features.


Assuntos
Peróxido de Hidrogênio/uso terapêutico , Neoplasias/terapia , Gases em Plasma/uso terapêutico , Soluções/uso terapêutico , Sinergismo Farmacológico , Humanos , Peróxido de Hidrogênio/química , Modelos Teóricos , Neoplasias/patologia , Nitritos/química , Nitritos/uso terapêutico , Espécies Reativas de Oxigênio/metabolismo , Soluções/efeitos da radiação
3.
Hist Philos Life Sci ; 43(2): 81, 2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34100155

RESUMO

Although every emerging infectious disease occurs in a unique context, the behaviour of previous pandemics offers an insight into the medium- and long-term outcomes of the current threat. Where an informative historical analogue exists, epidemiologists and policymakers should consider how the insights of the past can inform current forecasts and responses.


Assuntos
COVID-19/epidemiologia , Epidemiologia/história , Pandemias/história , História do Século XIX , História do Século XX , História do Século XXI , Humanos , Influenza Humana/epidemiologia , Influenza Humana/história , Modelos Teóricos
4.
Viruses ; 13(5)2021 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-34063465

RESUMO

The global COVID-19 spread has forced countries to implement non-pharmacological interventions (NPI) (i.e., mobility restrictions and testing campaigns) to preserve health systems. Spain is one of the most severely impacted countries, both clinically and economically. In an effort to support policy decision-making, we aimed to assess the impacts of different NPI on COVID-19 epidemiology, healthcare costs and Gross Domestic Product (GDP). A modified Susceptible-Exposed-Infectious-Removed epidemiological model was created to simulate the pandemic evolution. Its output was used to populate an economic model to quantify healthcare costs and GDP variation through a regression model which correlates NPI and GDP change from 42 countries. Thirteen scenarios combining different NPI were consecutively simulated in the epidemiological and economic models. Both increased testing and stringency could reduce cases, hospitalizations and deaths. While policies based on increased testing rates lead to higher healthcare costs, increased stringency is correlated with greater GDP declines, with differences of up to 4.4% points. Increased test sensitivity may lead to a reduction of cases, hospitalizations and deaths and to the implementation of pooling techniques that can increase throughput testing capacity. Alternative strategies to control COVID-19 spread entail differing economic outcomes. Decision-makers may utilize this tool to identify the most suitable strategy considering epidemiological and economic outcomes.


Assuntos
COVID-19/economia , COVID-19/epidemiologia , Controle de Doenças Transmissíveis/métodos , Política de Saúde/economia , Pandemias/economia , COVID-19/prevenção & controle , Análise Custo-Benefício , Governo , Produto Interno Bruto , Custos de Cuidados de Saúde , Humanos , Programas de Rastreamento , Modelos Econômicos , Modelos Teóricos , Técnicas de Diagnóstico Molecular , Pandemias/prevenção & controle , SARS-CoV-2 , Espanha/epidemiologia
5.
Sensors (Basel) ; 21(10)2021 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-34069145

RESUMO

Exoskeletons are the mechanical systems whose operation is carried out in close cooperation with the human body. In this paper, the authors describe a mathematical model of the hydraulic exoskeleton of a lower limb. The coordinates of characteristic points of the exoskeleton in the sagittal plane as a function of user height are presented. The mathematical models, kinematics, and kinetics equations were determined. The masses of the actuators and their dimensions were selected based on catalog data. The force distribution in the wearable system during the squat is shown. The proposed models allowed us to determine the trajectory of individual points of the exoskeleton and to determine the forces in hydraulic cylinders that are necessary to perform a specific displacement. The simulation results show that the joint moments depend linearly on actuator forces. The dynamics equations of the wearable system are non-linear. The inertia of the system depends on the junction variables and it proves that there are dynamic couplings between the individual axes of the exoskeleton.


Assuntos
Exoesqueleto Energizado , Fenômenos Biomecânicos , Humanos , Cinética , Extremidade Inferior , Modelos Teóricos
6.
Wiad Lek ; 74(5): 1109-1113, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34090273

RESUMO

OBJECTIVE: The aim: Developing integration training (educational) programs for medical and legal students, interns, masters, doctors. PATIENTS AND METHODS: Material and methods: When performing the work, on a set of search and analytical methods: analytical, bibliographic, systemic, informational, statistical; interdisciplinary interactive teaching methods for students of Sumy State University. RESULTS: Results: The results of the integrated training course are the formation of a new style of interdisciplinary relations between participants of the educational process and practical medicine and jurisprudence; new educational environment; classes with multi - and transdisciplinary experts-consultants; development of personal attitudes, future professional contacts, and practical skills. CONCLUSION: Conclusions: The introduction of new teaching methods using an interdisciplinary integrated approach increases the level of education quality (35.8% higher than the initial result) and conduct applied research in the field of public health, jurisprudence.


Assuntos
Doenças Transmissíveis , Pessoal de Saúde , Humanos , Modelos Teóricos , Estudantes , Universidades
7.
BMC Infect Dis ; 21(1): 503, 2021 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-34053446

RESUMO

BACKGROUND: In response to the ongoing COVID-19 pandemic, several countries adopted measures of social distancing to a different degree. For many countries, after successfully curbing the initial wave, lockdown measures were gradually lifted. In Belgium, such relief started on May 4th with phase 1, followed by several subsequent phases over the next few weeks. METHODS: We analysed the expected impact of relaxing stringent lockdown measures taken according to the phased Belgian exit strategy. We developed a stochastic, data-informed, meta-population model that accounts for mixing and mobility of the age-structured population of Belgium. The model is calibrated to daily hospitalization data and is able to reproduce the outbreak at the national level. We consider different scenarios for relieving the lockdown, quantified in terms of relative reductions in pre-pandemic social mixing and mobility. We validate our assumptions by making comparisons with social contact data collected during and after the lockdown. RESULTS: Our model is able to successfully describe the initial wave of COVID-19 in Belgium and identifies interactions during leisure/other activities as pivotal in the exit strategy. Indeed, we find a smaller impact of school re-openings as compared to restarting leisure activities and re-openings of work places. We also assess the impact of case isolation of new (suspected) infections, and find that it allows re-establishing relatively more social interactions while still ensuring epidemic control. Scenarios predicting a second wave of hospitalizations were not observed, suggesting that the per-contact probability of infection has changed with respect to the pre-lockdown period. CONCLUSIONS: Contacts during leisure activities are found to be most influential, followed by professional contacts and school contacts, respectively, for an impending second wave of COVID-19. Regular re-assessment of social contacts in the population is therefore crucial to adjust to evolving behavioral changes that can affect epidemic diffusion.


Assuntos
/epidemiologia , Modelos Teóricos , Pandemias , Bélgica/epidemiologia , Controle de Doenças Transmissíveis , Hospitalização , Humanos , Instituições Acadêmicas , Local de Trabalho
8.
Acta Psychol (Amst) ; 217: 103311, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33933836

RESUMO

Although symmetry, averageness, and sexual dimorphism are usually considered important to facial attractiveness, there are mixed findings regarding whether and how symmetry influences facial attractiveness. The present study introduced "facial normality" to explain the inconsistency of previous research. We hypothesized that symmetry only increased facial attractiveness when it improved facial normality. We manipulated symmetry and normality simultaneously on sixteen Chinese male faces and asked participants to rate the perceived symmetry, perceived normality, and facial attractiveness. The results demonstrated an interactive effect of symmetry and normality on facial attractiveness. The structural equation model results showed two paths from symmetry to facial attractiveness: (1) Symmetry reduced facial attractiveness by decreasing perceived normality; (2) Symmetry increased facial attractiveness by increasing the perceived symmetry and then improving perceived normality. In other words, perceived normality acted as a mediator between symmetry and facial attractiveness. The present study provides a solution to the different effects of symmetry on facial attractiveness in previous studies and suggests that future studies on symmetry and facial attractiveness should consider the mediating role of normality.


Assuntos
Face , Caracteres Sexuais , Grupo com Ancestrais do Continente Asiático , Beleza , Humanos , Masculino , Modelos Teóricos
9.
Sci Rep ; 11(1): 9545, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33953243

RESUMO

A novel coronavirus (SARS-CoV-2) has spread worldwide and led to high disease burden around the world. This study aimed to explore the key parameters of SARS-CoV-2 infection and to assess the effectiveness of interventions to control the coronavirus disease 2019 (COVID-19). A susceptible-exposed-infectious-asymptomatic-recovered (SEIAR) model was developed for the assessment. The information of each confirmed case and asymptomatic infection was collected from Ningbo Center for Disease Control and Prevention (CDC) to calculate the key parameters of the model in Ningbo City, China. A total of 157 confirmed COVID-19 cases (including 51 imported cases and 106 secondary cases) and 30 asymptomatic infections were reported in Ningbo City. The proportion of asymptomatic infections had an increasing trend. The proportion of elder people in the asymptomatic infections was lower than younger people, and the difference was statistically significant (Fisher's Exact Test, P = 0.034). There were 22 clusters associated with 167 SARS-CoV-2 infections, among which 29 cases were asymptomatic infections, accounting for 17.37%. We found that the secondary attack rate (SAR) of asymptomatic infections was almost the same as that of symptomatic cases, and no statistical significance was observed (χ2 = 0.052, P = 0.819) by Kruskal-Wallis test. The effective reproduction number (Reff) was 1.43, which revealed that the transmissibility of SARS-CoV-2 was moderate. If the interventions had not been strengthened, the duration of the outbreak would have lasted about 16 months with a simulated attack rate of 44.15%. The total attack rate (TAR) and duration of the outbreak would increase along with the increasing delay of intervention. SARS-CoV-2 had moderate transmissibility in Ningbo City, China. The proportion of asymptomatic infections had an increase trend. Asymptomatic infections had the same transmissibility as symptomatic infections. The integrated interventions were implemented at different stages during the outbreak, which turned out to be exceedingly effective in China.


Assuntos
/epidemiologia , /transmissão , Controle de Infecções/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Infecções Assintomáticas/epidemiologia , Número Básico de Reprodução , Criança , Pré-Escolar , China/epidemiologia , Cidades , Feminino , Humanos , Incidência , Lactente , Masculino , Pessoa de Meia-Idade , Modelos Teóricos , Adulto Jovem
10.
Math Biosci ; 337: 108614, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33961878

RESUMO

About a year into the pandemic, COVID-19 accumulates more than two million deaths worldwide. Despite non-pharmaceutical interventions such as social distance, mask-wearing, and restrictive lockdown, the daily confirmed cases remain growing. Vaccine developments from Pfizer, Moderna, and Gamaleya Institute reach more than 90% efficacy and sustain the vaccination campaigns in multiple countries. However, natural and vaccine-induced immunity responses remain poorly understood. There are great expectations, but the new SARS-CoV-2 variants demand to inquire if the vaccines will be highly protective or induce permanent immunity. Further, in the first quarter of 2021, vaccine supply is scarce. Consequently, some countries that are applying the Pfizer vaccine will delay its second required dose. Likewise, logistic supply, economic and political implications impose a set of grand challenges to develop vaccination policies. Therefore, health decision-makers require tools to evaluate hypothetical scenarios and evaluate admissible responses. Following some of the WHO-SAGE recommendations, we formulate an optimal control problem with mixed constraints to describe vaccination schedules. Our solution identifies vaccination policies that minimize the burden of COVID-19 quantified by the number of disability-adjusted years of life lost. These optimal policies ensure the vaccination coverage of a prescribed population fraction in a given time horizon and preserve hospitalization occupancy below a risk level. We explore "via simulation" plausible scenarios regarding efficacy, coverage, vaccine-induced, and natural immunity. Our simulations suggest that response regarding vaccine-induced immunity and reinfection periods would play a dominant role in mitigating COVID-19.


Assuntos
Vacinas contra COVID-19/imunologia , Vacinas contra COVID-19/farmacologia , COVID-19/imunologia , COVID-19/prevenção & controle , Vacinação em Massa , Modelos Teóricos , Avaliação de Processos e Resultados em Cuidados de Saúde/estatística & dados numéricos , Humanos , Vacinação em Massa/legislação & jurisprudência , Vacinação em Massa/normas , Vacinação em Massa/estatística & dados numéricos
11.
Comput Methods Programs Biomed ; 206: 106106, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33962319

RESUMO

BACKGROUND AND OBJECTIVE: The "Cardiac pump theory" and "Thoracic pump theory" are representative theories of cardiopulmonary resuscitation (CPR) mechanisms. Based on these theories, many studies on mathematical modeling have been performed to help understand hemodynamics during CPR. However, there are parts that do not yet properly reflect the physiology of CPR. Therefore, this study aims to develop a lumped parameter model of CPR that can more accurately reflect the current CPR physiology. METHODS: By adding compartments of the superior and inferior vena cava of the thoracic cavity to the existing CPR model, and the "Hybrid pump" mechanism was applied to simulate CPR. To compare the hemodynamics of the conventional CPR model and the developed CPR model, various conditions, such as active compression-decompression CPR with an impedance threshold valve device (ACD-CPR+ITV), head-up-tilt (HUT), and head-down-tilt (HDT), were simulated. The coronary perfusion pressure (CPP) was compared by modulating the compression ratio of the atrium and ventricle with the thoracic pump factor. RESULTS: The result for the comparison of coronary blood flow showed that the existing model is predominant in the compression phase, whereas the developed model is dominant in the relaxation phase. ACD-CPR + ITV results showed that the CPP decreased by 5 % in the existing model, and increased by about 46 % in the developed model, revealing a distinct hemodynamic difference between the two models. Likewise, as a result of comparing the hemodynamic differences of the two models according to the changes in tilt angle, the HUT showed similar trends, while the HDT showed slightly different results. The CPP varied accordingly with the ratio of the ventricular and atrial thoracic pump factor. CONCLUSION: Comparison of the hemodynamics with the existing model by simulating various conditions showed that the developed CPR model reflects the CPR physiology better. The model suggests that the hemodynamics may vary depending on the ventricle and atrium compression ratio. This study may provide an important basis for helping understand various situations and patient-specific hemodynamic characteristics during CPR through in-depth research, such as patient-specific model and parameter optimization.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca , Coração , Hemodinâmica , Humanos , Modelos Teóricos
12.
Comput Methods Programs Biomed ; 206: 106109, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33975182

RESUMO

BACKGROUND AND OBJECTIVES: Cutting and bleeding are often independent of each other in the traditional virtual surgery system because of the differences in the calculation of physical models and the lack of internal structure. In order to improve the fidelity of virtual surgery scene and the training value for surgeons, a new geometric combination of cutting and bleeding modules is introduced. METHODS: In this paper, we introduce a cutting model based on volume rendering and meshless method. The multidimensional parameters derived from the gray values are presented to participate in the calculation of both physical and geometric models, which distinguishes between different adjacent soft tissues. The bleeding simulation with improved physical properties and rendering algorithms of geometric model is proposed to meet several different bleeding states. After cutting procedures, the tearing parts can be judged through the vision and the tactile sensation. The initial velocity and rendering algorithm of bleeding particles are determined by the multidimensional parameters of the cutting position, which realizes the geometric combination of cutting and bleeding modules. RESULTS AND CONCLUSIONS: Simulation results show that tearing different tissue structures will produce corresponding bleeding states. When the skin and flesh are torn, the blood is slowly generated at the incision, and then diffuses to the surface of soft tissue. When the important blood vessels are ruptured, the blood gushes from the laceration. Compared with the conventional virtual surgery system, both visual effect and interactivity of the cutting and bleeding modules are improved in the proposed geometric combination.


Assuntos
Algoritmos , Interface Usuário-Computador , Simulação por Computador , Hemorragia , Humanos , Modelos Teóricos
13.
PLoS One ; 16(5): e0250775, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33939724

RESUMO

Since the apparition of the SRAS-Cov-2 in Wuhan in China, several countries have set diverse measures to stop its spread. Measures envisaged include national or local lockdown and travels ban. In the DRC, these measures have seriously prejudiced the economy of the country which is mainly informal. In this paper, a mathematical model for the spread of Covid-19 in Democratic Republic of Congo (DRC) taking into account the vulnerability of congolese economy is proposed. To mitigate the spreading of the virus no national lockdown is proposed, only individuals affected by the virus or suspicious are quarantined. The reproduction number for the Covid-19 is calculated and numerical simulations are performed using Python software. A clear advice for policymakers is deduced from the forecasting of the model.


Assuntos
Modelos Teóricos , /economia , /prevenção & controle , República Democrática do Congo/epidemiologia , Humanos , Quarentena
14.
Sci Rep ; 11(1): 9412, 2021 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-33941805

RESUMO

The spread of the novel coronavirus disease (COVID-19) continues to show that geographic barriers alone cannot contain the virus. Asymptomatic carriers play a critical role in the nature of this virus, which is rapidly escalating into a global pandemic. Asymptomatic carriers can inadvertently transmit the virus through the air stream. Many diseases can infect human bodies with tiny droplets or particles that carry various viruses and bacteria that are generated by the respiratory system of infected patients. This article presents the numerical results of the spread of droplets or particles in a room. The proposed numerical model in this work takes into account the sedimentation of particles or droplets under the action of gravitational sedimentation and transport in the room during the process of breathing and sneezing or coughing. Three different cases are numerically investigated taking into account normal breathing and coughing or sneezing, respectively, and three different rates of particle ejection from the mouth are considered. Navier-Stokes equations for incompressible flows were used to describe three-dimensional air flow inside ventilated rooms. The influence of ventilation rate on social distancing is also computationally investigated. It was found that particles can move up to 5 m with a decrease in concentration in the direction of the air flow. The conclusions made in this work show that, given the environmental conditions, the two meter social distance recommended by WHO is insufficient.


Assuntos
Microbiologia do Ar , /transmissão , Tosse , Expiração , Espirro , Humanos , Modelos Teóricos , Pandemias , Tamanho da Partícula
15.
BMC Infect Dis ; 21(1): 424, 2021 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-33952194

RESUMO

BACKGROUND: Although by late February 2020 the COVID-19 epidemic was effectively controlled in Wuhan, China, estimating the effects of interventions, such as transportation restrictions and quarantine measures, on the early COVID-19 transmission dynamics in Wuhan is critical for guiding future virus containment strategies. Since the exact number of infected cases is unknown, the number of documented cases was used by many disease transmission models to infer epidemiological parameters. This means that it was possible to produce biased estimates of epidemiological parameters and hence of the effects of intervention measures, because the percentage of all cases that were documented changed during the first 2 months of the epidemic, as a consequence of a gradually improving diagnostic capability. METHODS: To overcome these limitations, we constructed a stochastic susceptible-exposed-infected-quarantined-recovered (SEIQR) model, accounting for intervention measures and temporal changes in the proportion of new documented infections out of total new infections, to characterize the transmission dynamics of COVID-19 in Wuhan across different stages of the outbreak. Pre-symptomatic transmission was taken into account in our model, and all epidemiological parameters were estimated using the Particle Markov-chain Monte Carlo (PMCMC) method. RESULTS: Our model captured the local Wuhan epidemic pattern as two-peak transmission dynamics, with one peak on February 4 and the other on February 12, 2020. The impact of intervention measures determined the timing of the first peak, leading to an 86% drop in the Re from 3.23 (95% CI, 2.22 to 4.20) to 0.45 (95% CI, 0.20 to 0.69). The improved diagnostic capability led to the second peak and a higher proportion of documented infections. Our estimated proportion of new documented infections out of the total new infections increased from 11% (95% CI 1-43%) to 28% (95% CI 4-62%) after January 26 when more detection kits were released. After the introduction of a new diagnostic criterion (case definition) on February 12, a higher proportion of daily infected cases were documented (49% (95% CI 7-79%)). CONCLUSIONS: Transportation restrictions and quarantine measures together in Wuhan were able to contain local epidemic growth.


Assuntos
/epidemiologia , Modelos Teóricos , Número Básico de Reprodução , China/epidemiologia , Hospitalização/estatística & dados numéricos , Humanos , Controle de Infecções , Período de Incubação de Doenças Infecciosas , Cadeias de Markov , Método de Monte Carlo , Quarentena , Processos Estocásticos
16.
Parasit Vectors ; 14(1): 237, 2021 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-33957950

RESUMO

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease that is regionally distributed in Asia, with high fatality. Constructing the transmission model of SFTS could help provide clues for disease control and fill the gap in research on SFTS models. METHODS: We built an SFTS transmission dynamics model based on the susceptible-exposed-infectious-asymptomatic-recovered (SEIAR) model and the epidemiological characteristics of SFTS in Jiangsu Province. This model was used to evaluate the effect by cutting off different transmission routes and taking different interventions into account, to offer clues for disease prevention and control. RESULTS: The transmission model fits the reported data well with a minimum R2 value of 0.29 and a maximum value of 0.80, P < 0.05. Meanwhile, cutting off the environmental transmission route had the greatest effect on the prevention and control of SFTS, while isolation and shortening the course of the disease did not have much effect. CONCLUSIONS: The model we have built can be used to simulate the transmission of SFTS to help inform disease control. It is noteworthy that cutting off the environment-to-humans transmission route in the model had the greatest effect on SFTS prevention and control.


Assuntos
/transmissão , Animais , Vetores Aracnídeos/virologia , China/epidemiologia , Humanos , Incidência , Pessoa de Meia-Idade , Modelos Teóricos , /prevenção & controle , Carrapatos/virologia
17.
BMJ Glob Health ; 6(5)2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33947710

RESUMO

Since early 2020, global stakeholders have highlighted the significant gendered consequences of the COVID-19 pandemic, including increases in the risk of gender-based violence (GBV). Researchers have sought to inform the pandemic response through a diverse set of methodologies, including early efforts modelling anticipated increases in GBV. For example, in April 2020, a highly cited modelling effort by the United Nations Population Fund (UNFPA) and partners projected headline global figures of 31 million additional cases of intimate partner violence due to 6 months of lockdown, and an additional 13 million child marriages by 2030. In this paper, we discuss the rationale for using modelling to make projections about GBV, and use the projections released by UNFPA to draw attention to the assumptions and biases underlying model-based projections. We raise five key critiques: (1) reducing complex issues to simplified, linear cause-effect relationships, (2) reliance on a small number of studies to generate global estimates, (3) assuming that the pandemic results in the complete service disruption for existing interventions, (4) lack of clarity in indicators used and sources of estimates, and (5) failure to account for margins of uncertainty. We argue that there is a need to consider the motivations and consequences of using modelling data as a planning tool for complex issues like GBV, and conclude by suggesting key considerations for policymakers and practitioners in using and commissioning such projections.


Assuntos
Violência de Gênero , Modelos Teóricos , Feminino , Violência de Gênero/estatística & dados numéricos , Humanos
18.
Chemosphere ; 275: 130063, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33984898

RESUMO

The formation of molecular clusters makes influence on the atmosphere. The clusters of glutaric acid (GA) and common ammonia (A), amine (methylamine MA, dimethylamine DMA) and representative amide (urea U) along with water molecule were systematically studied theoretically. GA-A-nW (n = 1, 2), GA-MA-nW (n = 1, 2), GA-DMA-1W and GA-U-nW (n = 1-6) are predicted to be feasible thermodynamically with the hydrogen bonds as interaction force. GA and urea promote the clustering synergistically, and ammonia, methylamine, dimethylamine promote the clustering of small GA hydrates (n = 1-2), while inhibit that of large GA hydrates (n = 3-6). The results of humidity show that un-hydrate or mono-hydrate is the main form of GA-mbase-nW (m = 0, 1; n = 1-6) under relative humidity of 20%, 50% and 80%. The global minima remain dominant over the temperature range of 220-320 K. GA contributes more to the Rayleigh scattering properties than sulfuric acid. More importantly, the local minima can undergo isomerization to form the global minima crossing a free energy barrier ranging from 6.66 to 11.78 kcal mol-1. This study indicates that GA and base molecules play a synergistic role to promote the formation of clusters. We hope it can provide more insights on interesting clustering in theory.


Assuntos
Aminas , Amônia , Amidas , Análise por Conglomerados , Glutaratos , Modelos Teóricos
19.
Swiss Med Wkly ; 151: w20487, 2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33945149

RESUMO

Relevant pandemic-spread scenario simulations can provide guiding principles for containment and mitigation policies. We devised a compartmental model to predict the effectiveness of different mitigation strategies with a main focus on mass testing. The model consists of a set of simple differential equations considering the population size, reported and unreported infections, reported and unreported recoveries, and the number of COVID-19-inflicted deaths. We assumed that COVID-19 survivors are immune (e.g., mutations are not considered) and that the virus is primarily passed on by asymptomatic and pre-symptomatic individuals. Moreover, the current version of the model does not account for age-dependent differences in the death rates, but considers higher mortality rates due to temporary shortage of intensive care units. The model parameters have been chosen in a plausible range based on information found in the literature, but it is easily adaptable, i.e., these values can be replaced by updated information any time. We compared infection rates, the total number of people getting infected and the number of deaths in different scenarios. Social distancing or mass testing can contain or drastically reduce the infections and the predicted number of deaths when compared with a situation without mitigation. We found that mass testing alone and subsequent isolation of detected cases can be an effective mitigation strategy, alone and in combination with social distancing. It is of high practical relevance that a relationship between testing frequency and the effective reproduction number of the virus can be provided. However, unless one assumes that the virus can be globally defeated by reducing the number of infected persons to zero, testing must be upheld, albeit at reduced intensity, to prevent subsequent waves of infection. The model suggests that testing strategies can be equally effective as social distancing, though at much lower economic costs. We discuss how our mathematical model may help to devise an optimal mix of mitigation strategies against the COVID-19 pandemic. Moreover, we quantify the theoretical limit of contact tracing and by how much the effect of testing is enhanced, if applied to sub-populations with increased exposure risk or prevalence.


Assuntos
/prevenção & controle , Modelos Teóricos , Pandemias/prevenção & controle , Infecções Assintomáticas , /epidemiologia , Humanos , Programas de Rastreamento
20.
BMC Plant Biol ; 21(1): 222, 2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-34001008

RESUMO

BACKGROUND: Leaf length and width could be a functioning relationship naturally as plant designs. Single-vein leaves have the simplest symmetrical distribution and structural design, which means that fast-growing single-vein species could interpret the scheme more efficiently. The distribution of leaf length and width can be modulated for better adaptation, providing an informative perspective on the various operational strategies in an emergency, while this mechanism is less clear. Here we selected six age groups of Cunninghamia lanceolata pure forests, including saplings, juveniles, mature, and old-growth trees. We pioneered a tapering model to describe half-leaf symmetric distribution with mathematical approximation based on every measured leaf along developmental sequence, and evaluated the ratio of leaf basal part length to total length (called tipping leaf length ratio). RESULTS: The tipping leaf length ratio varied among different tree ages. That means the changes of tipping leaf length ratio and leaf shape are a significant but less-noticed reflection of trees tradeoff strategies at different growth stages. For instance, there exhibited relatively low ratio during sapling and juvenile, then increased with increasing age, showing the highest value in their maturity, and finally decreased on mature to old-growth transition. The tipping leaf length ratio serves as a cost-benefit ratio, thus the subtle changes in the leaf symmetrical distribution within individuals reveal buffering strategy, indicating the selection for efficient design of growth and hydraulic in their developmental sequences. CONCLUSIONS: Our model provides a physical explanation of varied signatures for tree operations in hydraulic buffering through growth stages, and the buffering strategy revealed from leaf distribution morphologically provides evidence on the regulation mechanism of leaf biomechanics, hydraulics and physiologies. Our insight contributes greatly to plant trait modeling, policy and management, and will be of interest to some scientists and policy makers who are involved in climate change, ecology and environment protection, as well as forest ecology and management.


Assuntos
Cunninghamia/crescimento & desenvolvimento , Cunninghamia/genética , Folhas de Planta/anatomia & histologia , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/genética , Árvores/crescimento & desenvolvimento , Árvores/genética , Fatores Etários , Florestas , Modelos Teóricos
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