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Effects of environmental variability on superspreading transmission events in stochastic epidemic models

Infectious Disease Modelling 2021年第1期6卷 560-583页

作者： Nika Shakiba Christina J.Edholm Blessing O.Emerenini Anarina L.Murillo Angela Peace Omar Saucedo Xueying Wang Linda J.S.Allen School of Biomedical Engineering University of British ColumbiaVancouverBCCanada Department of Mathematics Scripps CollegeClaremontCAUSA Department of Mathematics Oregon State UniversityCorvallisORUSA Department of Pediatrics and Center for Statistical Sciences Brown UniversityProvidenceRIUSA Department of Mathematics and Statistics Texas Tech UniversityLubbockTXUSA Department of Mathematics Virginia Polytechnic Institute and State UniversityBlacksburgVAUSA Department of Mathematics and Statistics Washington State UniversityPullmanWAUSA School of Mathematical Sciences Rochester Institute of TechnologyRochesterNYUSA

Superspreaders(individuals with a high propensity for disease spread)have played a pivotal role in recent emerging and re-emerging *** disease outbreak studies,host heterogeneity based on demographic(***,sex,vaccination status)and environmental(***,urban/rural residence,clinics)factors are critical for the spread of infectious diseases,such as Ebola and Middle East Respiratory Syndrome(MERS).Transmission rates can vary as demographic and environmental factors are altered naturally or due to modified behaviors in response to the implementation of public health *** this work,we develop stochastic models to explore the effects of demographic and environmental variability on human-to-human disease transmission rates among superspreaders in the case of Ebola and *** show that the addition of environmental variability results in reduced probability of outbreak occurrence,however the severity of outbreaks that do occur *** observations have implications for public health strategies that aim to control environmental variables.

关键词： Superspreader MERS Ebola environmental variability Stochastic models

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Female mate choice for multimodal courtship and the importance of the signaling background for selection on male ornamentation

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Current Zoology 2013年第2期59卷 200-209页

作者： Jay A. STAFSTROM Eileen A. HEBETS School of Biological Sciences University of Nebraska Lincoln NE 68588-0118 USA

Conspicuous visual ornaments are frequently incorporated into complex courtship displays that integrate signal com- ponents from multiple sensory modalities. Mature male Schizocosa crassipes （Walckenaer, 1837） wolf spiders wave, arch, and tap their ornamented forelegs in a visual courtship display that simultaneously incorporates seismic components. To determine the importance of modality-specific signal components in female mate choice, we used a signal ablation design and compared the mating frequency of female-male pairs across signaling environments with manipulated modality-specific transmission properties. We found that the successful transmission of isolated visual or seismic signaling was sufficient for mating success; neither sig- naling modality was necessary. Additionally, the environment enabling the successful transmission of composite, multimodal dis- plays yielded the highest mating frequencies. Our results indicate the presence of selection from S. crassipes females for multi- modal courtship and suggest that multimodal signaling may facilitate mating across variable signaling environments. We next ex- plored the influence of ornamentation per se on female choice by phenotypically manipulating males into two groups：（i） intact （brushes present） and （ii） shaved （brushes absent）. We compared the mating frequencies of intact versus shaved males in the presence versus absence of seismic signaling. Males with brushes intact had higher mating frequencies than shaved males, but only under specific signaling conditions - in the presence of seismic signaling. Female choice for male brushes then appears de- pendent on the signaling background, making brushes themselves an unlikely target of direct selection. Our results emphasize the complex nature of female choice, highlighting the potential for both trait interactions and environment-dependent selection [Cur- rent Zoology 59 （2）： 200-209, 2013].

关键词： Enhancement environmental variability Inter-signal interaction Sexual selection

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Spatial Distribution of Land Cover and Vegetation Activity along Topographic Gradient in an Arid River Valley, SW China

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Journal of Mountain Science 2009年第3期6卷 274-285页

作者： LIU Wen XU Xianli LUO Jiancheng SHEN Zhanfeng ZHONG Qiuhai Department of Automatic Control School of Automation Beijing Institute of Technology Beijing 100081 China State Key Laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Institute of Remote Sensing Applications Chinese Academy of Sciences Beijing 100101 China Centre for Hydrology Micrometeorology and Climate Change Department of Civil and Environmental Engineering University College Cork Cork Ireland

Anthropogenic activities have become more and more important in characterizing the landscape, but their impacts are still restricted by natural environments. This paper discusses the interactions of anthropogenic activity, vegetation activity and topography through describing the spatial distribution of land cover and vegetation activity (represented by Normalized Difference Vegetation Index, NDVI) along topographic gradient in a mountainous area of southwestern China. Our results indicate that the existing landscape pattern is controlled by anthropogenic activities as well as topographic factors. Intensive anthropogenic activities mainly occur in areas with relatively low elevation, gentle and concave slopes, as these areas are easy and convenient to attain for human. Because of the destruction by human, some land cover types (mainly grassland and shrub) are only found in relatively harsher environments. This study also finds that topographic wetness index (W) used in other places only reflects runoff generation capacity, but not indicate the real spatial pattern of soil water content in this area. The relationships between NDVI and W, and NDVI and length slope factor (LSF) show that runoff and erosion have complex effects on vegetation activity. Greater values of W and LSF will lead to stronger capacity to produce runoff and transport sediment, and thereby increase soil water content and soil deposition, whereas beyond a certain threshold runoff and erosion are so strong that they would destruct vegetation growth. This study provides information needed to successfully restore native vegetation, improve land management, and promote sustainable development in mountainous areas, especially for developing regions.

关键词： Vertical distribution of land cover Anthropogenic activity Vegetation activity environmental variability China

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