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Basic reproductive number

Mark A Lewis, Nathan G Marculis, Zhongwei Shen
To understand the effects that the climate change has on the evolution of species as well as the genetic consequences, we analyze an integrodifference equation (IDE) models for a reproducing and dispersing population in a spatio-temporal heterogeneous environment described by a shifting climate envelope. Our analysis on the IDE focuses on the persistence criterion, travelling wave solutions, and the inside dynamics. First, the persistence criterion, characterizing the global dynamics of the IDE, is established in terms of the basic reproduction number...
January 13, 2018: Journal of Mathematical Biology
Jinxian Li, Weiqiang Li, Zhen Jin
The spread of an infectious disease may depend on the structure of the network. To study the influence of the structure parameters of the network on the spread of the epidemic, we need to put these parameters into the epidemic model. The method of moment closure introduces structure parameters into the epidemic model. In this paper, we present a new moment closure epidemic model based on the approximation of third-order motifs in networks. The order of a motif defined in this paper is determined by the number of the edges in the motif, rather than by the number of nodes in the motif as defined in the literature...
January 9, 2018: Mathematical Biosciences
Camille L Duran, Colette A Abbey, Kayla J Bayless
STUDY QUESTION: Can primary human uterine microvascular endothelial cells (UtMVECs) be used as a model to study uterine angiogenic responses in vitro that are relevant in pregnancy? SUMMARY ANSWER: UtMVECs demonstrated angiogenic responses when stimulated with proangiogenic factors, including sphingosine 1-phosphate (S1P), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), physiological levels of wall shear stress (WSS), human chorionic gonadotropin (hCG) and various combinations of estrogen and progesterone...
December 21, 2017: Molecular Human Reproduction
Xiaodan Sun, Yanni Xiao, Zhihang Peng, Ning Wang
Intervention measures among men who have sex with men (MSM) are usually designed to reduce the frequency of high risk behaviors (within-community level), but unfortunately may change the contact network and consequently increase the opportunity for them to have sex with new partners (between-community level). A multi-community periodic model on complex network is proposed to study the two-side effects of interventions on HIV transmission among MSM in China, in which the wanning process of the impacts of interventions are modelled...
January 11, 2018: Scientific Reports
Xinzhi Ren, Yanni Tian, Lili Liu, Xianning Liu
In this paper, a reaction-diffusion within-host HIV model is proposed. It incorporates cell mobility, spatial heterogeneity and cell-to-cell transmission, which depends on the diffusion ability of the infected cells. In the case of a bounded domain, the basic reproduction number [Formula: see text] is established and shown as a threshold: the virus-free steady state is globally asymptotically stable if [Formula: see text] and the virus is uniformly persistent if [Formula: see text]. The explicit formula for [Formula: see text] and the global asymptotic stability of the constant positive steady state are obtained for the case of homogeneous space...
January 5, 2018: Journal of Mathematical Biology
Chayu Yang, Jin Wang
The intrinsic dynamics of bacteria often play an important role in the transmission and spread of waterborne infectious diseases. In this paper, we construct mathematical models for waterborne infections and analyze two types of nontrivial bacterial dynamics: logistic growth, and growth with Allee effects. For the model with logistic growth, we find that regular threshold dynamics take place, and the basic reproduction number can be used to characterize disease extinction and persistence. In contrast, the model with Allee effects exhibits much more complex dynamics, including the existence of multiple endemic equilibria and the presence of backward bifurcation and forward hysteresis...
December 29, 2017: Mathematical Biosciences
I Aznar, K Frankena, S J More, J O'Keeffe, G McGrath, M C M de Jong
In the UK and Ireland, Bacille Calmette-Guérin (BCG) vaccination of badgers has been suggested as one of a number of strategies to control or even eradicate Mycobacterium bovis infection in badgers. In this manuscript, we present the results of a badger field trial conducted in Ireland and discuss how the novel trial design and analytical methods allowed the effects of vaccination on protection against infection and, more importantly, on transmission to be estimated. The trial area was divided into three zones North to South (A, B and C) where vaccination coverages of 0, 50 and 100%, respectively, were applied...
January 1, 2018: Preventive Veterinary Medicine
Xuelian Cui, Narisa Zhao
Social networks are rarely static, and they typically have time-varying network topologies. A great number of studies have modeled temporal networks and explored social contagion processes within these models; however, few of these studies have considered community structure variations. In this paper, we present a study of how the time-varying property of a modular structure influences the information dissemination. First, we propose a continuous-time Markov model of information diffusion where two parameters, mobility rate and community attractiveness, are introduced to address the time-varying nature of the community structure...
December 2017: Chaos
Michael T Meehan, Daniel G Cocks, James M Trauer, Emma S McBryde
We introduce and analyze coupled, multi-strain epidemic models designed to simulate the emergence and dissemination of mutant (e.g. drug-resistant) pathogen strains. In particular, we investigate the mathematical and biological properties of a general class of multi-strain epidemic models in which the infectious compartments of each strain are coupled together in a general manner. We derive explicit expressions for the basic reproduction number of each strain and highlight their importance in regulating the system dynamics (e...
December 27, 2017: Mathematical Biosciences
João Pedro Alves-Lopes, Jan-Bernd Stukenborg
BACKGROUND: In recent decades, a broad range of strategies have been applied to model the testicular microenvironment in vitro. These models have been utilized to study testicular physiology and development. However, a system that allows investigations into testicular organogenesis and its impact in the spermatogonial stem-cell (SSC) niche in vitro has not been developed yet. Recently, the creation of tissue-specific organ-like structures called organoids has resurged, helping researchers to answer scientific questions that previous in vitro models could not help to elucidate...
December 21, 2017: Human Reproduction Update
Floor Biemans, Piter Bijma, Natasja M Boots, Mart C M de Jong
Digital Dermatitis (DD) is a claw disease mainly affecting the hind feet of dairy cattle. Digital Dermatitis is an infectious disease, transmitted via the environment, where the infectious "agent" is a combination of bacteria. The standardized classification for DD lesions developed by Döpfer et al. (1997) and extended by Berry et al. (2012) has six distinct classes: healthy (M0), an active granulomatous area of 0-2 cm (M1), an ulcerative lesion of >2 cm (M2), an ulcerative lesion covered by a scab (M3), alteration of the skin (M4), and a combination of M4 and M1 (M4...
December 22, 2017: Epidemics
Yong Li, Xianning Liu, Lianwen Wang
Mumps is a common childhood viral disease and children have been vaccinated throughout the world since 1967. The incidence of mumps has increased with more than 300,000 young people infected with mumps annually in mainland China since 2005. Therefore, we designed and analyzed long-term mumps surveillance data in an SVEILR (susceptible-vaccinated-exposed-severely infectious-mildly infectious-recovered) dynamic transmission model with optimized parameter values to describe the dynamics of mumps infections in China...
December 26, 2017: International Journal of Environmental Research and Public Health
Nick Scott, Sigurður Ólafsson, Magnús Gottfreðsson, Thorarinn Tyrfingsson, Valgerdur Rúnarsdóttir, Ingunn Hansdottir, Ubaldo Benitez Hernandez, Guðrún Sigmundsdóttir, Margaret Hellard
BACKGROUND AND AIMS: In Iceland a nationwide program has been launched offering direct-acting antiviral (DAA) treatment for everyone living with hepatitis C virus (HCV). We estimate (1) the time and treatment scale-up required to achieve the World Health Organization's HCV elimination target of an 80% reduction in incidence; and (2) the ongoing frequency of HCV testing and harm reduction coverage among people who inject drugs (PWID) required to minimize the likelihood of future HCV outbreaks occurring...
December 20, 2017: Journal of Hepatology
Deshun Sun, Fei Liu
In this paper, a hepatitis B virus (HBV) model with an incubation period and delayed state and control variables is firstly proposed. Furthermore, the combination treatment is adopted to have a longer-lasting effect than mono-therapy. The equilibrium points and basic reproduction number are calculated, and then the local stability is analyzed on this model. We then present optimal control strategies based on the Pontryagin's minimum principle with an objective function not only to reduce the levels of exposed cells, infected cells and free viruses nearly to zero at the end of therapy, but also to minimize the drug side-effect and the cost of treatment...
December 19, 2017: Interdisciplinary Sciences, Computational Life Sciences
Jinglei Wang, Yang Qiu, Feng Cheng, Xiaohua Chen, Xiaohui Zhang, Haiping Wang, Jiangping Song, Mengmeng Duan, Haohui Yang, Xixiang Li
BACKGROUND: Radish (Raphanus sativus L.) belongs to the family Brassicaceae, and is an economically important root crop grown worldwide. Flowering is necessary for plant propagation, but it is also an important agronomic trait influencing R. sativus fleshy taproot yield and quality in the case of an imbalance between vegetative and reproductive growth. There is currently a lack of detailed information regarding the pathways regulating the flowering genes or their evolution in R. sativus...
December 19, 2017: BMC Genomics
Janine L Brown
The ability to track gonadal function is facilitated by the use of endocrine and ultrasound techniques, both of which are important tools for optimizing reproduction and ensuring sustainability of fragile populations. With so many species now endangered, captive breeding is increasingly viewed as a means to sustain important insurance populations. As reproduction is key to species survival, understanding how to control and monitor ovarian function is vital. Through decades of study, we now have a greater understanding of the diversity, and plasticity, of reproductive mechanisms across taxa...
December 8, 2017: Theriogenology
Ezekiel Dangbé, Damakoa Irépran, Antoine Perasso, David Békollé
Cholera is a bacterial disease, its spread is strongly influenced by environmental factors and some socio-economic factors such as hygiene standards and nutrition of the population. This paper is devoted to the modelling of the impact of climatic factors and human behaviour on the spread of cholera. The mathematical modelling incorporates the direct transmission and the indirect transmission due to environmental knowledge. Taking into account the effect of the intra-annual variation of climatic factors on the transmission of cholera, a non-autonomous ordinary differential equations is proposed to describe the dynamics of the transmission of cholera...
December 12, 2017: Mathematical Biosciences
Jui-Chun Chang, Ming-Jer Chen, Hwa-Fen Guu, Ya-Fang Chen, Yu-Chiao Yi, Hsiao-Fan Kung, Li-Yu Chen, Min-Min Chou
OBJECTIVE: There are increasing concerns regarding the adverse effects associated with control ovarian hyperstimulation (COH) in both endometrial and uterine environments. With the "segmentation treatment policy" of assisted reproductive techniques (ART), endometrial problems may be obviated through embryo cryopreservation. However, it remains unclear if the "freeze-all policy" offers a better outcome when compared with fresh embryo transfer (ET). To clarify this, we compared the cumulative live birth rates (CLBRs) between these two patient populations...
December 2017: Taiwanese Journal of Obstetrics & Gynecology
Wentao Fan, Yuliang Xu, Pu Zhang, Peng Chen, Yiran Zhu, Ziqiang Cheng, Xiaona Zhao, Yongxia Liu, Jianzhu Liu
The present study investigated the molecular evolution of nucleocapsid protein (NP) in different Newcastle disease virus (NDV) genotypes. The evolutionary timescale and rate were estimated using the Bayesian Markov chain Monte Carlo (MCMC) method. The p-distance, Bayesian skyline plot (BSP), and positively selected sites were also analyzed. The MCMC tree indicated that NDV diverged about 250 years ago with a rapid evolution rate (1.059 × 10-2 substitutions/site/year) and that different NDV genotypes formed three lineages...
November 14, 2017: Oncotarget
S S Hayer, K VanderWaal, R Ranjan, J K Biswal, S Subramaniam, J K Mohapatra, G K Sharma, M Rout, B B Dash, B Das, B R Prusty, A K Sharma, C Stenfeldt, A Perez, A H Delgado, M K Sharma, L L Rodriguez, B Pattnaik, J Arzt
Foot-and-mouth disease (FMD) is an important transboundary disease with substantial economic impacts. Although between-herd transmission of the disease has been well studied, studies focusing on within-herd transmission using farm-level outbreak data are rare. The aim of this study was to estimate parameters associated with within-herd transmission, host physiological factors and FMD virus (FMDV) persistence using data collected from an outbreak that occurred at a large, organized dairy farm in India. Of 1,836 regularly vaccinated, adult dairy cattle, 222 had clinical signs of FMD over a 39-day period...
December 5, 2017: Transboundary and Emerging Diseases
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