scholarly journals Experimental demonstration of the impact of hard and soft selection regimes on polymorphism maintenance in spatially heterogeneous environments†

Evolution ◽  
2018 ◽  
Vol 72 (8) ◽  
pp. 1677-1688 ◽  
Author(s):  
Romain Gallet ◽  
Rémy Froissart ◽  
Virginie Ravigné
Keyword(s):  
Heterogeneous Environments ◽  
Experimental Demonstration ◽  
Soft Selection ◽  
The Impact

Development of Strategies for Glycopeptide Synthesis: An Overview on the Glycosidic Linkage

2020 ◽  
Vol 24 (21) ◽  
pp. 2475-2497
Author(s):  
Andrea Verónica Rodríguez-Mayor ◽  
German Jesid Peralta-Camacho ◽  
Karen Johanna Cárdenas-Martínez ◽  
Javier Eduardo García-Castañeda
Keyword(s):  
Chemical Synthesis ◽  
Solid Phase ◽  
Building Blocks ◽  
Heterogeneous Environments ◽  
Phase Synthesis ◽  
Low Concentrations ◽  
Biological Sources ◽  
Synthetic Routes ◽  
The Impact ◽  
Potential Use

Glycoproteins and glycopeptides are an interesting focus of research, because of their potential use as therapeutic agents, since they are related to carbohydrate-carbohydrate, carbohydrate-protein, and carbohydrate-lipid interactions, which are commonly involved in biological processes. It has been established that natural glycoconjugates could be an important source of templates for the design and development of molecules with therapeutic applications. However, isolating large quantities of glycoconjugates from biological sources with the required purity is extremely complex, because these molecules are found in heterogeneous environments and in very low concentrations. As an alternative to solving this problem, the chemical synthesis of glycoconjugates has been developed. In this context, several methods for the synthesis of glycopeptides in solution and/or solid-phase have been reported. In most of these methods, glycosylated amino acid derivatives are used as building blocks for both solution and solid-phase synthesis. The synthetic viability of glycoconjugates is a critical parameter for allowing their use as drugs to mitigate the impact of microbial resistance and/or cancer. However, the chemical synthesis of glycoconjugates is a challenge, because these molecules possess multiple reaction sites and have a very specific stereochemistry. Therefore, it is necessary to design and implement synthetic routes, which may involve various protection schemes but can be stereoselective, environmentally friendly, and high-yielding. This review focuses on glycopeptide synthesis by recapitulating the progress made over the last 15 years.

scholarly journals Reducing the Influence of Environmental Factors on Performance of a Diffusion-Based Personal Exposure Kit

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4637
Author(s):  
Huixin Zong ◽  
Peter Brimblecombe ◽  
Li Sun ◽  
Peng Wei ◽  
Kin-Fai Ho ◽  
...  
Keyword(s):  
Exposure Assessment ◽  
Real Time ◽  
Low Cost ◽  
Personal Exposure ◽  
Sensor Technology ◽  
Heterogeneous Environments ◽  
Mathematical Algorithms ◽  
Personal Exposure Assessment ◽  
Address System ◽  
The Impact

Sensor technology has enabled the development of portable low-cost monitoring kits that might supplement many applications in conventional monitoring stations. Despite the sensitivity of electrochemical gas sensors to environmental change, they are increasingly important in monitoring polluted microenvironments. The performance of a compact diffusion-based Personal Exposure Kit (PEK) was assessed for real-time gaseous pollutant measurement (CO, O3, and NO2) under typical environmental conditions encountered in the subtropical city of Hong Kong. A dynamic baseline tracking method and a range of calibration protocols to address system performance were explored under practical scenarios to assess the performance of the PEK in reducing the impact of rapid changes in the ambient environment in personal exposure assessment applications. The results show that the accuracy and stability of the ppb level gas measurement is enhanced even in heterogeneous environments, thus avoiding the need for data post-processing with mathematical algorithms, such as multi-linear regression. This establishes the potential for use in personal exposure monitoring, which has been difficult in the past, and for reporting more accurate and reliable data in real-time to support personal exposure assessment and portable air quality monitoring applications.

Cooperation Strategies for P2P Content Distribution in Cellular Mobile Networks

2011 ◽  
pp. 152-165
Author(s):  
Tobias Hoßfeld ◽  
Michael Duelli ◽  
Dirk Staehle ◽  
Phuoc Tran-Gia
Keyword(s):  
Cellular Networks ◽  
Mobile Networks ◽  
Content Distribution ◽  
Vertical Handover ◽  
Mobility Model ◽  
Computational Time ◽  
Heterogeneous Environments ◽  
Cellular Mobile ◽  
The Impact

The performance of P2P content distribution in cellular networks depends highly on the cooperation and coordination of heterogeneous and often selfish mobile users. The major challenges are the identification of problems arising specifically in cellular mobile networks and the development of new cooperation strategies to overcome these problems. In the coherent previous chapter, the authors focused on the selfishness of users in such heterogeneous environments. This discussion is now extended by emphasizing the impact of mobility and vertical handover between different wireless access technologies. An abstract mobility model is required to allow the performance evaluation in feasible computational time. As a result, the performance in today’s and future cellular networks is predicted and new approaches to master heterogeneity in cellular networks are derived.

The Value of Web Design Standards for Mobile Computing

2011 ◽  
pp. 214-226
Author(s):  
Matt Germonprez ◽  
Michel Avital ◽  
Nikhil Srinivasan
Keyword(s):  
Mobile Computing ◽  
Resource Availability ◽  
Web Design ◽  
Heterogeneous Environments ◽  
Design Standards ◽  
Device Independence ◽  
Cascading Style Sheets ◽  
Hypertext Markup Language ◽  
The Impact ◽  
Build Systems

The multiple and ever-evolving standards that govern mobile computing result in multilayered heterogeneous environments of mobile devices and services. Thus, as mobile computing becomes more prevalent, it is important that designers build systems that support as many unique, in-use, and userdefined characteristics as possible. This study explores the related effects of two existing standardized technologies: hypertext markup language (HTML) and cascading style sheets (CSS). Furthermore, whereas we investigate the impact of the CSS standard in the context of computing in general and mobile computing in particular, we also focus on two emerging roles of this standard: device independence and usability. Our findings suggest that the application of the CSS standard can improve data delivery across independent devices with varied bandwidth and resource availability, thereby providing device independence and improved usability respectively. We demonstrate that through their effect on device independence and usability, CSS plays an important role in the evolution, expansion, and openness of mobile computing.

scholarly journals The evolution of stage-specific virulence: differential selection of parasites in juveniles

2018 ◽  
Author(s):  
Ryosuke Iritani ◽  
Elisa Visher ◽  
Mike Boots
Keyword(s):  
Infectious Disease ◽  
Stage Structure ◽  
Juvenile Stage ◽  
Oncorhynchus Gorbuscha ◽  
Heterogeneous Environments ◽  
Previous Theory ◽  
Differential Selection ◽  
Host Stage ◽  
The Impact ◽  
Specific Virulence

AbstractThe impact of infectious disease is often very different in juveniles and adults, but theory has focused on the drivers of stage-dependent defense in hosts rather than the potential for stage-dependent virulence evolution. Stage-structure has the potential to be important to the evolution of pathogens because it exposes parasites to heterogeneous environments in terms of both host characteristics and transmission routes. We develop a stage-structured (juvenile-adult) epidemiological model and examine the evolutionary outcomes of stage-specific virulence under the classic assumption of a transmission-virulence trade-off. We show that selection on virulence against adults remains consistent with the classic theory. However, the evolution of juvenile virulence is sensitive to both demography and transmission pathway with higher virulence against juveniles being favored either when the transmission pathway is assortative (juveniles preferentially interact together) and the juvenile stage is short, or in contrast when the transmission pathway is disassortative and the juvenile stage is long. These results highlight the potentially profound effects of host stage-structure on determining parasite virulence in nature. This new perspective may have broad implications for both understanding and managing disease severity.Impact summaryUnderstanding the evolution of parasite virulence remains one of the most important questions in evolutionary ecology. Virulence is often very different in young and old hosts, but previous theory has presumed that these differences are attributed to adaptation in host defense rather than parasite adaptation. However, stage-structure within host populations can expose parasites to heterogeneous environments, which may lead to differential selection on parasite virulence (stage-specific virulence). Surprisingly, no study has investigated the effects of hosts’ stage-structure on the evolution of stage-specific virulence. We present a theoretical analysis to examine when selection can favor higher virulence against juveniles (juvenile-virulence) versus adults (adult-virulence). Our key result is that higher juvenile-virulence is selected for either when the transmission is assortative within age classes and maturation is slow, or when the transmission is disassortative (occurring predominantly between-classes) and maturation is relatively fast. These at first sight contrasting outcomes can be understood as adaptation to the exploitation of the more available host stage. Although the data on assortativity in infectious disease systems is limited, empirical studies for the virulence of Great Island Virus in guillemots (Uria aalge) and for salmon louse in pink salmon (Oncorhynchus gorbuscha) are consistent with our predictions. Our work provides testable predictions for stage-specific virulence and presents a novel mechanism that may explain variation in virulence in nature. There are also management implications for conservation, public health, vaccination programs, and farming to understanding the drivers of stage dependent virulence.

scholarly journals WaterWorld: a self-parameterising, physically based model for application in data-poor but problem-rich environments globally

2012 ◽  
Vol 44 (5) ◽  
pp. 748-769 ◽  
Author(s):  
Mark Mulligan
Keyword(s):  
Climate Change ◽  
Water Balance ◽  
Large Scale ◽  
Policy Support ◽  
Heterogeneous Environments ◽  
Adaptation To Climate Change ◽  
Management Interventions ◽  
Very High Spatial Resolution ◽  
Physically Based ◽  
The Impact

This paper describes a spatially explicit, physically based global model for water balance. Its key innovations include the fact that it comes with all data required for application, is very high spatial resolution (1 km or 1-hectare resolution) and yet global in extent and is particularly well suited to heterogeneous environments with little or no available data. The model, WaterWorld, is capable of producing a hydrological baseline representing the mean water balance for 1950–2000 and allows users to apply ensemble scenarios for climate change or examine the impact of policy options for land cover change or land management interventions. WaterWorld is focused on policy support, especially in conservation hydrology and development applications and is delivered through a simple web interface, requiring little local capacity for use. The paper discusses the paucity of hydrological data and the urgency of hydrological problems in much of the less-developed world, which reinforce the need for tools like WaterWorld. We discuss the types of hydrological problems that models might contribute to managing and the requirements of models applied to such problems. By way of example, applications of WaterWorld to understanding large-scale patterns of water resources and uncertainty around adaptation to climate change are described.

scholarly journals Topological flocking models in spatially heterogeneous environments

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Parisa Rahmani ◽  
Fernando Peruani ◽  
Pawel Romanczuk
Keyword(s):  
Large Scale ◽  
Interaction Network ◽  
Effective Density ◽  
Quenched Disorder ◽  
Heterogeneous Environments ◽  
Heterogeneous Environment ◽  
Active Systems ◽  
Scale Properties ◽  
Distinct Features ◽  
The Impact

AbstractFlocking models with metric and topological interactions are supposed to exhibit distinct features, as for instance the presence and absence of moving polar bands. On the other hand, quenched disorder (spatial heterogeneities) has been shown to dramatically affect large-scale properties of active systems with metric interactions, while the impact of quenched disorder on active systems with metric-free interactions has remained, until now, unexplored. Here, we show that topological flocking models recover several features of metric ones in homogeneous media, when placed in a heterogeneous environment. In particular, we find that order is long-ranged even in the presence of spatial heterogeneities, and that the heterogeneous environment induces an effective density-order coupling facilitating emergence of traveling bands, which are observed in wide regions of parameter space. We argue that such a coupling results from a fluctuation-induced rewiring of the topological interaction network, strongly enhanced by the presence of spatial heterogeneities.

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