The Experts below are selected from a list of 708 Experts worldwide ranked by ideXlab platform
Bernhard Mayer - One of the best experts on this subject based on the ideXlab platform.
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efficient unbiased variance reduction techniques for monte carlo simulations of radiative transfer in cloudy atmospheres the solution
Journal of Quantitative Spectroscopy & Radiative Transfer, 2011Co-Authors: Robert Buras, Bernhard MayerAbstract:Abstract We present five new variance reduction techniques applicable to Monte Carlo simulations of radiative transfer in the atmosphere: detector directional importance sampling, n-tuple local estimate, prediction-based splitting and Russian Roulette, and circum-solar virtual importance sampling. With this set of methods it is possible to simulate remote sensing instruments accurately and quickly. In contrast to all other known techniques used to accelerate Monte Carlo simulations in cloudy atmospheres – except for two methods limited to narrow angle lidars – the presented methods do not make any approximations, and hence do not bias the result. Nevertheless, these methods converge as quickly as any of the biasing acceleration techniques, and the probability distribution of the simulation results is almost perfectly normal. The presented variance reduction techniques have been implemented into the Monte Carlo code MYSTIC (“Monte Carlo code for the physically correct tracing of photons in cloudy atmospheres”) in order to validate the techniques.
Esther Garcés - One of the best experts on this subject based on the ideXlab platform.
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A Game of Russian Roulette for a Generalist Dinoflagellate Parasitoid: Host Susceptibility Is the Key to Success.
Frontiers in Microbiology, 2016Co-Authors: Elisabet Alacid, Marta Turon, Katherina Petrou, Myung Gil Park, Esther GarcésAbstract:Marine microbial interactions involving eukaryotes and their parasites play an important role in shaping the structure of phytoplankton communities. These interactions may alter population densities of the main host, which in turn may have consequences for the other concurrent species. The effect generalist parasitoids exert on a community is strongly dependent on the degree of host specificity. Parvilucifera sinerae is a generalist parasitoid able to infect a wide range of dinoflagellates, including toxic-bloom-forming species. A density-dependent chemical cue has been identified as the trigger for the activation of the infective stage. Together these traits make Parvilucifera-dinoflagellate hosts a good model to investigate the degree of specificity of a generalist parasitoid, and the potential effects that it could have at the community level. Here, we present for the first time, the strategy by which a generalist dinoflagellate parasitoid seeks out its host and determine whether it exhibits host preferences, highlighting key factors in determining infection. Our results demonstrate that in its infective stage, P. sinerae is able to sense potential hosts, but does not actively select among them. Instead, the parasitoids contact the host at random, governed by the encounter probability rate and once encountered, the chance to penetrate inside the host cell and develop the infection strongly depends on the degree of host susceptibility. As such, their strategy for persistence is more of a game of Russian Roulette, where the chance of survival is dependent on the susceptibility of the host. Our study identifies P. sinerae as a potential key player in bloom community ecology, where in mixed dinoflagellate communities consisting of hosts that are highly susceptible to infection, parasitoid preferences may mediate coexistence between host species, reducing the dominance of the superior competitor. Alternatively, it may increase competition, leading to species exclusion. If, however, highly susceptible hosts are absent from the community, the parasitoid population could suffer a dilution effect maintaining a lower parasitoid density. Therefore, both host community structure and host susceptibility will determine infectivity in the field.
Niels Piot - One of the best experts on this subject based on the ideXlab platform.
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interaction effects of different drivers of wild bee decline and their influence on host pathogen dynamics
Current opinion in insect science, 2018Co-Authors: Ivan Meeus, Matti Pisman, Guy Smagghe, Niels PiotAbstract:Wild bee decline is a multi-factorial problem, yet it is crucial to understand the impact of a single driver. Hereto the interaction effects of wild bee decline with multiple natural and anthropogenic stressors need to be clear. This is also true for the driver 'pathogens', as stressor induced disturbances of natural host-pathogen dynamics can unbalance settled virulence equilibria. Invasive species, bee domestication, habitat loss, climate changes and insecticides are recognized drivers of wild bee decline, but all influence host-pathogen dynamics as well. Many wild bee pathogens have multiple hosts, which relaxes the host-density limitation of virulence evolution. In conclusion, disturbances of bee-pathogen dynamics can be compared to a game of Russian Roulette.
Elisabet Alacid - One of the best experts on this subject based on the ideXlab platform.
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A Game of Russian Roulette for a Generalist Dinoflagellate Parasitoid: Host Susceptibility Is the Key to Success.
Frontiers in Microbiology, 2016Co-Authors: Elisabet Alacid, Marta Turon, Katherina Petrou, Myung Gil Park, Esther GarcésAbstract:Marine microbial interactions involving eukaryotes and their parasites play an important role in shaping the structure of phytoplankton communities. These interactions may alter population densities of the main host, which in turn may have consequences for the other concurrent species. The effect generalist parasitoids exert on a community is strongly dependent on the degree of host specificity. Parvilucifera sinerae is a generalist parasitoid able to infect a wide range of dinoflagellates, including toxic-bloom-forming species. A density-dependent chemical cue has been identified as the trigger for the activation of the infective stage. Together these traits make Parvilucifera-dinoflagellate hosts a good model to investigate the degree of specificity of a generalist parasitoid, and the potential effects that it could have at the community level. Here, we present for the first time, the strategy by which a generalist dinoflagellate parasitoid seeks out its host and determine whether it exhibits host preferences, highlighting key factors in determining infection. Our results demonstrate that in its infective stage, P. sinerae is able to sense potential hosts, but does not actively select among them. Instead, the parasitoids contact the host at random, governed by the encounter probability rate and once encountered, the chance to penetrate inside the host cell and develop the infection strongly depends on the degree of host susceptibility. As such, their strategy for persistence is more of a game of Russian Roulette, where the chance of survival is dependent on the susceptibility of the host. Our study identifies P. sinerae as a potential key player in bloom community ecology, where in mixed dinoflagellate communities consisting of hosts that are highly susceptible to infection, parasitoid preferences may mediate coexistence between host species, reducing the dominance of the superior competitor. Alternatively, it may increase competition, leading to species exclusion. If, however, highly susceptible hosts are absent from the community, the parasitoid population could suffer a dilution effect maintaining a lower parasitoid density. Therefore, both host community structure and host susceptibility will determine infectivity in the field.
Ivan Meeus - One of the best experts on this subject based on the ideXlab platform.
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interaction effects of different drivers of wild bee decline and their influence on host pathogen dynamics
Current opinion in insect science, 2018Co-Authors: Ivan Meeus, Matti Pisman, Guy Smagghe, Niels PiotAbstract:Wild bee decline is a multi-factorial problem, yet it is crucial to understand the impact of a single driver. Hereto the interaction effects of wild bee decline with multiple natural and anthropogenic stressors need to be clear. This is also true for the driver 'pathogens', as stressor induced disturbances of natural host-pathogen dynamics can unbalance settled virulence equilibria. Invasive species, bee domestication, habitat loss, climate changes and insecticides are recognized drivers of wild bee decline, but all influence host-pathogen dynamics as well. Many wild bee pathogens have multiple hosts, which relaxes the host-density limitation of virulence evolution. In conclusion, disturbances of bee-pathogen dynamics can be compared to a game of Russian Roulette.
