Optimization of magnetic actuation protocol to enhance mass transfer in solid/liquid microfluidic systems

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The dynamic properties of a 250 m magnetic microparticle in a time varying magnetic field have been studied in a PDMS microreactor with a diameter of 13 mm using a dual coupled quadrupolar arrangement of electromagnets. A sinusoidal applied magnetic field has dictated a circular motion of the particles in the microreactor in the frequency range below 0.6 Hz. Different circular motion modes have been observed at higher frequencies of the applied field. The particular symmetric arrangement of the magnets has allowed a non-steady-state motion with variation in velocity between magnetic poles. The motion of magnetic particle has been described in terms of average velocity and mean square deviation from average velocity. The effect of actuation protocol parameters (frequency, magnetic field strength and phase shift) on particle velocity and acceleration has been investigated. The maximum average velocity of 0.016 m/s has been observed under an optimized actuation protocol. The mass transfer rate towards the particle surface is mainly influenced by the average velocity while the effect of acceleration/deceleration of the particle has an order of magnitude less influence

Magnetic actuation of microparticles for mass transfer enhancement

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The motion of magnetic microparticles (250μm diameter) in a circular microfluidic reactor with a diameter of 10 mm under time dependent magnetic field has been studied using CFD code COMSOL. The effect of actuation protocol on the local and average particle velocity has been investigated. The local Sh numbers were obtained as a function of angular particle position in the range of Re numbers between 0.05 and 10 while the particle velocity was changed over two orders of magnitude. Under time dependent magnetic field, the thickness of the boundary layer continuously changes which results in an increased mass transfer towards the particle surface under periodic particle velocity conditions as compared to steady state velocity conditions. A good agreement between numerical and experimental data has been observed

Long-Distance Wind-Dispersal of Spores in a Fungal Plant Pathogen: Estimation of Anisotropic Dispersal Kernels from an Extensive Field Experiment

Given its biological significance, determining the dispersal kernel (i.e., the distribution of dispersal distances) of spore-producing pathogens is essential. Here, we report two field experiments designed to measure disease gradients caused by sexually- and asexually-produced spores of the wind-dispersed banana plant fungus Mycosphaerella fijiensis. Gradients were measured during a single generation and over 272 traps installed up to 1000 m along eight directions radiating from a traceable source of inoculum composed of fungicide-resistant strains. We adjusted several kernels differing in the shape of their tail and tested for two types of anisotropy. Contrasting dispersal kernels were observed between the two types of spores. For sexual spores (ascospores), we characterized both a steep gradient in the first few metres in all directions and rare long-distance dispersal (LDD) events up to 1000 m from the source in two directions. A heavy-tailed kernel best fitted the disease gradient. Although ascospores distributed evenly in all directions, average dispersal distance was greater in two different directions without obvious correlation with wind patterns. For asexual spores (conidia), few dispersal events occurred outside of the source plot. A gradient up to 12.5 m from the source was observed in one direction only. Accordingly, a thin-tailed kernel best fitted the disease gradient, and anisotropy in both density and distance was correlated with averaged daily wind gust. We discuss the validity of our results as well as their implications in terms of disease diffusion and management strategy

Data analysis manual for coconut researchers

This publication on ”Data Analysis Manual for Coconut Researchers” provides basic statistical concepts and includes: sampling methods, frequency distribution of observations, estimation and tests of significance, analysis and relationships between variables, basic principles for planning and conducting coconut field trials, basic experimental designs for coconut trials, experimental designs for coconut trials with modified blocking, experimental designs for multiple factors, analysis of multilocation trials, and multivariate analysis and determination of genetic distance. The manual provide details of experimental designs to use in agronomic, breeding trails and germplasm characterization and evaluation. The data used for most of the examples in this manual are actual research data on coconut generated at the Central Plantation Crops Research Institute (CPCRI), Kasaragod, India. Almost all the analyses described in this manual have been described with some suitable examples and step-by-step procedures. Using this tutorial-type manual, coconut researchers as well as other researchers can practice computation by themselves using the examples provided in this manual and then use the same procedure to analyze their own data.The manual also include introduction to 'R' and its use to perform statistical analysis for data presentation in this manual and are presented as Appendices. The objective of the appendices is to explain how the 'R' statistical software can be used to perform the analyses presented in the manual. Data in the Tables of this manual have been copied into text files readable by 'R'. The contents of these text files are printed at the end of respective appendices. A gray background is sued for 'R' commands and a frame with white background for the results returned by 'R'. It is easy to test the 'R' commands by copying the text of the gray areas into the 'R' console. It is therefore expected that this publication will help the scientific community to better plan and manage their experiments and, analyze and interpret their experimental data

Genetic identification of source and likely vector of a widespread marine invader

The identification of native sources and vectors of introduced species informs their ecological and evolutionary history and may guide policies that seek to prevent future introductions. Population genetics provides a powerful set of tools to identify origins and vectors. However, these tools can mislead when the native range is poorly sampled or few molecular markers are used. Here, we traced the introduction of the Asian seaweed Gracilaria vermiculophylla (Rhodophyta) into estuaries in coastal western North America, the eastern United States, Europe, and northwestern Africa by genotyping more than 2,500 thalli from 37 native and 53 non-native sites at mitochondrial cox1 and 10 nuclear microsatellite loci. Overall, greater than 90% of introduced thalli had a genetic signature similar to thalli sampled from the coastline of northeastern Japan, strongly indicating this region served as the principal source of the invasion. Notably, northeastern Japan exported the vast majority of the oyster Crassostrea gigas during the 20th century. The preponderance of evidence suggests G. vermiculophylla may have been inadvertently introduced with C. gigas shipments and that northeastern Japan is a common source region for estuarine invaders. Each invaded coastline reflected a complex mix of direct introductions from Japan and secondary introductions from other invaded coastlines. The spread of G. vermiculophylla along each coastline was likely facilitated by aquaculture, fishing, and boating activities. Our ability to document a source region was enabled by a robust sampling of locations and loci that previous studies lacked and strong phylogeographic structure along native coastlines

Day versus night use of forest by red and roe deer as determined by Corine Land Cover and Copernicus Tree Cover Density: assessing use of geographic layers in movement ecology

Diel use of forest and open habitats by large herbivores is linked to species-specific needs of multiple and heterogeneous resources. However, forest cover layers might deviate considerably for a given landscape, potentially affecting evaluations of animals’ habitat use. We assessed inconsistency in the estimates of diel forest use by red and roe deer at GPS location and home range (HR) levels, using two geographic layers: Tree Cover Density (TCD) and Corine Land Cover (CLC). We first measured the classification mismatch of red and roe deer GPS locations between TCD and CLC, also with respect to habitat units’ size. Then, we used generalized Least Squares models to assess the proportional use of forest at day and night at the GPS location and HR levels, both with TCD and CLC. About 20% of the GPS locations were inconsistently classified as forest or open habitat by the two layers, particularly within smaller habitat units. Overall proportion of forest and open habitat, though, was very similar for both layers. In all populations, both deer species used forest more at day than at night and this pattern was more evident with TCD than with CLC. However, at the HR level, forest use estimates were only marginally different between the two layers. When estimating animal habitat use, geographic layer choice requires careful evaluation with respect to ecological questions and target species. Habitat use analyses based on GPS locations are more sensitive to layer choice than those based on home ranges.publishedVersio

Trust predicts COVID-19 prescribed and discretionary behavioral intentions in 23 countries

The worldwide spread of a new coronavirus (SARS-CoV-2) since December 2019 has posed a severe threat to individuals well-being. While the world at large is waiting that the released vaccines immunize most citizens, public health experts suggest that, in the meantime, it is only through behavior change that the spread of COVID-19 can be controlled. Importantly, the required behaviors are aimed not only at safeguarding one s own health. Instead, individuals are asked to adapt their behaviors to protect the community at large. This raises the question of which social concerns and moral principles make people willing to do so. We considered in 23 countries (N = 6948) individuals willingness to engage in prescribed and discretionary behaviors, as well as country-level and individual-level factors that might drive such behavioral intentions. Results from multilevel multiple regressions, with country as the nesting variable, showed that publicized number of infections were not significantly related to individual intentions to comply with the prescribed measures and intentions to engage in discretionary prosocial behaviors. Instead, psychological differences in terms of trust in government, citizens, and in particular toward science predicted individuals behavioral intentions across countries. The more people endorsed moral principles of fairness and care (vs. loyalty and authority), the more they were inclined to report trust in science, which, in turn, statistically predicted prescribed and discretionary behavioral intentions. Results have implications for the type of intervention and public communication strategies that should be most effective to induce the behavioral changes that are needed to control the COVID-19 outbreak