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population dynamics

Jungsoo Lee, Ahee Lee, Heegoo Kim, Won Hyuk Chang, Yun-Hee Kim
Most previous stroke studies have been performed in heterogeneous patient populations. Moreover, the brain network might demonstrate different recovery dynamics according to lesion location. In this study, we investigated variation in motor network alterations according to lesion location. Forty patients with subcortical ischemic stroke were enrolled. Patients were divided into two groups: 21 patients with supratentorial stroke (STS) and 19 patients with infratentorial stroke (ITS). All patients underwent resting-state functional magnetic resonance imaging and behavioral assessment at 2 weeks and 3 months poststroke...
August 18, 2018: Human Brain Mapping
Ursula Föger-Samwald, Christian Knecht, Thomas Stimpfl, Thomas Szekeres, Katharina Kerschan-Schindl, Peter Mikosch, Peter Pietschmann, Wolfgang Sipos
BACKGROUND: Although chronic alcohol consumption in adults is an established risk factor for osteoporotic fractures, there is a huge gap in our knowledge about bone effects of binge drinking in adolescents. The aim of this pilot study was therefore to assess skeletal effects of binge alcohol drinking using prepubescent pigs as a large animal model. METHODS: Piglets aged two months were offered alcohol orally as a mixture of hard liquor and apple juice. Those with the highest propensity to drink alcohol were included in the experiment and received 1...
August 18, 2018: Alcoholism, Clinical and Experimental Research
Caterina Vitale, Eva Kisdi
Under the threat of predation, a species of prey can evolve to its own extinction. Matsuda and Abrams (Theor Popul Biol 45:76-91, 1994a) found the earliest example of evolutionary suicide by demonstrating that the foraging effort of prey can evolve until its population dynamics cross a fold bifurcation, whereupon the prey crashes to extinction. We extend this model in three directions. First, we use critical function analysis to show that extinction cannot happen via increasing foraging effort. Second, we extend the model to non-equilibrium systems and demonstrate evolutionary suicide at a fold bifurcation of limit cycles...
August 17, 2018: Bulletin of Mathematical Biology
Gidon Winters, Dennis Otieno, Shabtai Cohen, Christina Bogner, Gideon Ragowloski, Indira Paudel, Tamir Klein
Drought-induced tree mortality has been recently increasing and is expected to increase further under warming climate. Conversely, tree species that survive under arid conditions might provide vital information on successful drought resistance strategies. Although Acacia (Vachellia) species dominate many of the globe's deserts, little is known about their growth dynamics and water-use in situ. Stem diameter dynamics, leaf phenology, and sap flow were monitored during 3 consecutive years in five Acacia raddiana trees and five Acacia tortilis trees in the Arid Arava Valley, southern Israel (annual precipitation 20-70 mm, restricted to October-May)...
August 18, 2018: Oecologia
Valeriu Balaban, Sean Lim, Gaurav Gupta, James Boedicker, Paul Bogdan
From microbial communities to cancer cells, many such complex collectives embody emergent and self-organising behaviour. Such behaviour drives cells to develop composite features such as formation of aggregates or expression of specific genes as a result of cell-cell interactions within a cell population. Currently, we lack universal mathematical tools for analysing the collective behaviour of biological swarms. To address this, we propose a multifractal inspired framework to measure the degree of emergence and self-organisation from scarce spatial (geometric) data and apply it to investigate the evolution of the spatial arrangement of Enterobacter cloacae aggregates...
August 17, 2018: Scientific Reports
Logan Chariker, Robert Shapley, Lai-Sang Young
We studied mechanisms for cortical gamma-band activity in the cerebral cortex and identified neurobiological factors that affect such activity. This was done by analyzing the behavior of a previously-developed, data-driven, large-scale network model that simulated many visual functions of monkey V1 cortex [Chariker et al 2016]. Gamma activity was an emergent property of the model. The model's gamma activity, like that of the real cortex, was 1) episodic, 2) variable in frequency and phase, and 3) graded in power with stimulus variables like orientation...
August 17, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Lauren M Fletcher, Javier Atalah, Barrie M Forrest
The colonial ascidian Didemnum vexillum is a high-profile marine invader, with a geographically widespread distribution after introductions to several temperate regions. D. vexillum has been the focus of several eradication and control programmes globally and the need for specific biological knowledge that relates to establishment processes, persistence, impacts and potential for spread remains. The present study describes temporal patterns of D. vexillum percent cover on experimental substrates over 1.5-years in relation to seasonality of substratum availability, in conjunction with key physical (i...
August 7, 2018: Marine Environmental Research
Neal R Smith, James M Trauer, Manoj Gambhir, Jack S Richards, Richard J Maude, Jonathan M Keith, Jennifer A Flegg
BACKGROUND: Much of the extensive research regarding transmission of malaria is underpinned by mathematical modelling. Compartmental models, which focus on interactions and transitions between population strata, have been a mainstay of such modelling for more than a century. However, modellers are increasingly adopting agent-based approaches, which model hosts, vectors and/or their interactions on an individual level. One reason for the increasing popularity of such models is their potential to provide enhanced realism by allowing system-level behaviours to emerge as a consequence of accumulated individual-level interactions, as occurs in real populations...
August 17, 2018: Malaria Journal
Devika Nadkarni, Sara Gravelyn, Monica Brova, Sarem Rashid, Randy Yee, Donovan Guttieres, Katie Clifford, Darash Desai, Muhammad Zaman
BACKGROUND: Our objective is to estimate the effects of therapeutic oxytocin supply chain factors and social determinants of health on patient access to oxytocin in low-income settings using system dynamics modeling. Postpartum hemorrhage (PPH), a major cause of maternal mortality disproportionately affects women in low and middle income countries (LMICs). The World Health Organization recommends therapeutic oxytocin as the frontline uterotonic for PPH management and prevention. However, lack of access to quality therapeutic oxytocin in Tanzania, and throughout Sub-Saharan Africa, continues to result in a high number of preventable maternal deaths...
August 17, 2018: BMC Health Services Research
Andriy V Trailin, Tamara N Nykonenko, Tetyana I Ostapenko, Sergiy R Vildanov, Olexandr S Nykonenko
OBJECTIVES: Our aim was to evaluate which histologic lesions in a donor kidney were associated with graft function up to 5 years and with its dynamics. MATERIALS AND METHODS: We retrospectively investigated the association between acute and chronic individual histologic lesions and composite scores in preimplant and postreperfusion biopsies from deceased-donor (n = 101) and living-donor (n = 29) kidneys with initial graft function and function at discharge, at 6 months, and at 5 years and slopes of estimated glomerular filtration rate from discharge to 6 months and from 6 months to 5 years...
August 17, 2018: Experimental and Clinical Transplantation
Salida Mirzoeva, Xin Tong, Bryan B Bridgeman, Michael P Plebanek, Olga V Volpert
We have previously demonstrated that apigenin promotes the expression of antiangiogenic protein thrombospondin-1 (TSP1) via a mechanism driven by mRNA-binding protein HuR. Here, we generated a novel mouse model with whole-body THBS-1 gene knockout on SKH-1 genetic background, which allows studies of UVB-induced acute skin damage and carcinogenesis and tests TSP1 involvement in apigenin's anticancer effects. Apigenin significantly inhibited UVB-induced carcinogenesis in the wild-type (WT) animals but not in TSP1 KO (TKO) mice, suggesting that TSP1 is a critical component of apigenin's chemopreventive function in UVB-induced skin cancer...
August 14, 2018: Neoplasia: An International Journal for Oncology Research
Stavros Stavrakis, Gregor Holzner, Jaebum Choo, Andrew deMello
Recently, microfluidic-based flow cytometry platforms have been shown to be powerful tools for the manipulation and analysis of single cells and micron-sized particles in flow. That said, current microfluidic flow cytometers are limited in both their analytical throughput and spatial resolution, due to their reliance on single point interrogation schemes. Conversely, high-speed imaging techniques can be applied to a wide variety of problems in which analyte molecules are manipulated at high linear velocities...
August 14, 2018: Current Opinion in Biotechnology
Abby Spangler, Emily Y Su, April M Craft, Patrick Cahan
Directed differentiation of pluripotent stem cells provides an accessible system to model development. However, the distinct cell types that emerge, their dynamics, and their relationship to progenitors in the early embryo has been difficult to decipher because of the cellular heterogeneity inherent to differentiation. Here, we used a combination of bulk RNA-Seq, single cell RNA-Seq, and bioinformatics analyses to dissect the cell types that emerge during directed differentiation of mouse embryonic stem cells as embryoid bodies and we compared them to spatially and temporally resolved transcriptional profiles of early embryos...
July 29, 2018: Stem Cell Research
Tingting Luo, Lu Liu, Xuejuan Shen, David M Irwin, Ming Liao, Yongyi Shen
After the 2009 pandemic H1N1 outbreak, this new reassortant virus replaced the previous seasonal H1N1 and established itself in human populations. In 2014-2015, the H1N1/pdm2009 pandemic strain caused the worst influenza outbreak in India in recent years. It is still unclear whether this outbreak was due to a genetic change in the H1N1/pdm2009 virus. Here, we collected all available data from India, and used data from other South and Southeast Asian countries (Bangladesh, Myanmar, Nepal, Singapore, and Vietnam) that are geographically nearby India for comparison, to examine the evolutionary dynamics of this influenza virus...
August 14, 2018: Infection, Genetics and Evolution
Liqiang Zhong, Daming Li, Minghua Wang, Xiaohui Chen, Wenji Bian, Guangwei Zhu
The changes of bacterial community composition in a channel catfish nursery pond with cage-pond integration system were investigated by sequencing of the 16S rRNA gene through Illumina miseq sequencing platforms. A total of 1,362,877 sequences and 1440 operational taxonomic units (OTUs) were obtained. Further analysis showed that the dominant phyla in cage and pond groups were similar, including Actinobacteria, Cyanobacteria, Proteobacteria and Bacteroidetes, although a significant difference was detected between them by ANOSIM (P<0...
August 17, 2018: Canadian Journal of Microbiology
Kirsten Henderson, Michel Loreau
It is estimated that the Earth's biocapacity is unable to meet current demands, which begs the question: is a sustainable future possible for both humans and the environment? The UN projects a human population of approximately 11 billion by the end of the 21st century; requiring additional agricultural land, greater demands for natural resources, and technological advancements. We model human population over the next century, emphasizing feedbacks between natural and agricultural resource availability and human demography...
August 17, 2018: PLoS Computational Biology
Guoqiang Li, Peike Gao, Bo Zhi, Bing Fu, Ge Gao, Zhaohui Chen, Mengli Gao, Mengmeng Wu, Ting Ma
Microbial phylogenetic diversity and species interactions in natural ecosystems have been investigated extensively, but our knowledge about their ecological roles, community dynamics and succession patterns is far from complete. This knowledge is essential to understand the complicated interactions of microorganisms in natural ecosystems. Here, an artificial ecosystem model of microorganisms was constructed from oil-well products and cultivated in a chemostat to investigate the succession pattern of alkane-degrading bacteria, a functional population in oil reservoirs...
August 16, 2018: Environmental Microbiology
Tapiwa Ganyani, Christel Faes, Gerardo Chowell, Niel Hens
The standard mass action, which assumes that infectious disease transmission occurs in well-mixed populations, is popular for formulating compartmental epidemic models. Compartmental epidemic models often follow standard mass action for simplicity and to gain insight into transmission dynamics as it often performs well at reproducing disease dynamics in large populations. In this work, we formulate discrete time stochastic susceptible-infected-removed models with linear (standard) and nonlinear mass action structures to mimic varying mixing levels...
August 16, 2018: Statistics in Medicine
Nathan Pacoureau, Matthieu Authier, Karine Delord, Christophe Barbraud
A fundamental endeavor in population ecology is to identify the drivers of population dynamics. A few empirical studies included the effect of prey abundance when investigating simultaneously the effects of density-dependence and climate factors on marine top-predator population dynamics. Our aim was to unravel the mechanisms forcing population dynamics of an apex consumer seabird, the south polar skua, using long-term climatic and population time series of the consumer and its prey in Terre Adélie, Antarctica...
August 17, 2018: Oecologia
Nastassja L Fischer, Rafael Peres, Mario Fiorani
Social media has gained increasing importance in many aspects of everyday life, from building relationships to establishing collaborative networks between individuals worldwide. Sharing behavior is an essential part of maintaining these dynamic networks. However, the precise neural factors that could be related to sharing behavior in online communities remain unclear. In this study, we recorded electroencephalographic (EEG) oscillations of human subjects while they were watching short videos. The subjects were later asked to evaluate the videos based on how much they liked them and whether they would share them...
2018: Frontiers in Behavioral Neuroscience
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