31 research outputs found
An extreme case of plant-insect co-diversification: figs and fig-pollinating wasps
It is thought that speciation in phytophagous insects is often due to colonization of novel host plants, because radiations of plant and insect lineages are typically asynchronous. Recent phylogenetic comparisons have supported this model of diversification for both insect herbivores and specialized pollinators. An exceptional case where contemporaneous plant insect diversification might be expected is the obligate mutualism between fig trees (Ficus species, Moraceae) and their pollinating wasps (Agaonidae, Hymenoptera). The ubiquity and ecological significance of this mutualism in tropical and subtropical ecosystems has long intrigued biologists, but the systematic challenge posed by >750 interacting species pairs has
hindered progress toward understanding its evolutionary history. In particular, taxon sampling and analytical tools have been insufficient for large-scale co-phylogenetic analyses. Here, we sampled nearly 200 interacting pairs of fig and wasp species from across the globe. Two
supermatrices were assembled: on average, wasps had sequences from 77% of six genes (5.6kb), figs had sequences from 60% of five genes (5.5 kb), and overall 850 new DNA sequences were generated for this study. We also developed a new analytical tool, Jane 2, for event-based phylogenetic reconciliation analysis of very large data sets. Separate Bayesian
phylogenetic analyses for figs and fig wasps under relaxed molecular clock assumptions indicate Cretaceous diversification of crown groups and contemporaneous divergence for nearly half of all fig and pollinator lineages. Event-based co-phylogenetic analyses further support the co-diversification hypothesis. Biogeographic analyses indicate that the presentday distribution of fig and pollinator lineages is consistent with an Eurasian origin and subsequent dispersal, rather than with Gondwanan vicariance. Overall, our findings indicate that the fig-pollinator mutualism represents an extreme case among plant-insect interactions of coordinated dispersal and long-term co-diversification
Space plasma physics science opportunities for the lunar orbital platform - Gateway
The Lunar Orbital Platform - Gateway (LOP - Gateway, or simply Gateway) is a crewed platform that will be assembled and operated in the vicinity of the Moon by NASA and international partner organizations, including ESA, starting from the mid-2020s. It will offer new opportunities for fundamental and applied scientific research. The Moon is a unique location to study the deep space plasma environment. Moreover, the lunar surface and the surface-bounded exosphere are interacting with this environment, constituting a complex multi-scale interacting system. This paper examines the opportunities provided by externally mounted payloads on the Gateway in the field of space plasma physics, heliophysics and space weather, and also examines the impact of the space environment on an inhabited platform in the vicinity of the Moon. It then presents the conceptual design of a model payload, required to perform these space plasma measurements and observations. It results that the Gateway is very well-suited for space plasma physics research. It allows a series of scientific objectives with a multi-disciplinary dimension to be addressed
The Comet Interceptor Mission
Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESA's F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ÎV capability of 600Â ms-1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000Â km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes - B1, provided by the Japanese space agency, JAXA, and B2 - that will follow different trajectories through the coma. While the main probe passes at a nominal 1000Â km distance, probes B1 and B2 will follow different chords through the coma at distances of 850Â km and 400Â km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the mission's science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule
The Comet Interceptor Mission
Here we describe the novel, multi-point Comet Interceptor mission. It is dedicated to the exploration of a little-processed long-period comet, possibly entering the inner Solar System for the first time, or to encounter an interstellar object originating at another star. The objectives of the mission are to address the following questions: What are the surface composition, shape, morphology, and structure of the target object? What is the composition of the gas and dust in the coma, its connection to the nucleus, and the nature of its interaction with the solar wind? The mission was proposed to the European Space Agency in 2018, and formally adopted by the agency in June 2022, for launch in 2029 together with the Ariel mission. Comet Interceptor will take advantage of the opportunity presented by ESAâs F-Class call for fast, flexible, low-cost missions to which it was proposed. The call required a launch to a halo orbit around the Sun-Earth L2 point. The mission can take advantage of this placement to wait for the discovery of a suitable comet reachable with its minimum ÎV capability of 600 msâ1. Comet Interceptor will be unique in encountering and studying, at a nominal closest approach distance of 1000 km, a comet that represents a near-pristine sample of material from the formation of the Solar System. It will also add a capability that no previous cometary mission has had, which is to deploy two sub-probes â B1, provided by the Japanese space agency, JAXA, and B2 â that will follow different trajectories through the coma. While the main probe passes at a nominal 1000 km distance, probes B1 and B2 will follow different chords through the coma at distances of 850 km and 400 km, respectively. The result will be unique, simultaneous, spatially resolved information of the 3-dimensional properties of the target comet and its interaction with the space environment. We present the missionâs science background leading to these objectives, as well as an overview of the scientific instruments, mission design, and schedule
Les cornets polaires: étude d'une région clef de l'interface vent solaire-magnétosphÚre à l'aide des données Cluster.
The direct access to ionosphere offered by the polar cusps to the solar wind plasma makes it a key region to study the solar wind / magnetosphere interface. It has been chosen to study the nature of the UBF waves and their interactions with the plasma in the most distant part of the polar cusp which the Cluster II data.The detailed study of an event shows that the injections of solar wind plasma are detected in simultaneity with strong electromagnetic UBF activity. The wave analyses highlight the alfvĂ©nic nature of the fluctuations and the mixing of various modes inside a single wave burst. That result is achievable only with a multi-satellite analysis, in this case the k- filtering technique. These results are generalized, showing the importance of the UBF waves in the solar wind plasma penetration into the magnetosphere.L'accĂšs direct Ă l'ionosphĂšre que les cornets polaires permettent au plasma du vent solaire font de ceux-ci une rĂ©gion-clef pour l'Ă©tude de l'interface entre le vent solaire et la magnĂ©tosphĂšre. Il a Ă©tĂ© choisi d'Ă©tudier la nature des ondes UBF et de leur interaction avec le plasma dans la partie la plus distante des cornets polaires avec les donnĂ©es Cluster.Une Ă©tude de cas dĂ©taillĂ©e montre que les injections de plasma du vent solaire s'accompagnent d'une forte activitĂ© Ă©lectromagnĂ©tique. L'analyse des ondes, met en valeur la nature alfvĂ©nique dominante de ces fluctuations, ainsi que le mĂ©lange des modes dans une mĂȘme bouffĂ©e, rĂ©sultat obtenu par une analyse pluri-satellitaire, ici le filtrage-en-k. Les ondes d'AlfvĂ©n sont identifiĂ©es dans le domaine cinĂ©tique. Les interactions possibles avec le plasma sont recherchĂ©es. Ces rĂ©sultats sont pour partie gĂ©nĂ©ralisĂ©s, montrant l'importance des ondes UBF dans la pĂ©nĂ©tration du plasma du vent solaire dans la magnĂ©tosphĂšre terrestre
Electromagnetic ion cyclotron waves in the helium branch induced by multiple electromagnetic ion cyclotron triggered emissions
Electromagnetic ion cyclotron (EMIC) triggered emissions with rising tones between the H+ and He+ cyclotron frequencies were found in the inner magnetosphere by the recent Cluster observations. Another type of EMIC wave with a constant frequency is occasionally observed below the He+ cyclotron frequency after the multiple EMIC triggered emissions. We performed a self-consistent hybrid simulation with a one-dimensional cylindrical magnetic flux model approximating the dipole magnetic field of the Earth's inner magnetosphere. In the presence of energetic protons with a sufficient density and temperature anisotropy, multiple EMIC triggered emissions are reproduced due to the nonlinear wave growth mechanism of rising-tone chorus emissions, and a constant frequency wave in the He+ EMIC branch is subsequently generated. Through interaction with the multiple EMIC rising-tone emissions, the velocity distribution function of the energetic protons is strongly modified. Because of the pitch angle scattering of the protons, the gradient of the distribution in velocity phase space is enhanced along the diffusion curve of the He+ branch wave, resulting in the linear growth of the EMIC wave in the He+ branch
Les cornets polaires (étude d'une région clef de l'interface vent solaire-magnétosphÚre à l'aide des données Cluster)
L'accĂšs direct Ă l'ionosphĂšre que les cornets polaires permettent au plasma du vent solaire font de ceux-ci une rĂ©gion-clef pour l'Ă©tude de l interface entre le vent solaire et la magnĂ©tosphĂšre. Il a Ă©tĂ© choisi d'Ă©tudier la nature des ondes UBF et de leur interaction avec le plasma dans la partie la plus distante des cornets polaires avec les donnĂ©es Cluster. Une Ă©tude de cas dĂ©taillĂ©e montre que les injections de plasma du vent solaire s'accompagnent d'une forte activitĂ© Ă©lectromagnĂ©tique. L'analyse des ondes, met en valeur la nature alfvĂ©nique dominante de ces fluctuations, ainsi que le mĂ©lange des modes dans une mĂȘme bouffĂ©e, rĂ©sultat obtenu par une analyse pluri-satellitaire, ici le filtrage-en-k. Les ondes d'AlfvĂ©n sont identifiĂ©es dans le domaine cinĂ©tique. Les interactions possibles avec le plasma sont recherchĂ©es. Ces rĂ©sultats sont pour partie gĂ©nĂ©ralisĂ©s, montrant l'importance des ondes UBF dans la pĂ©nĂ©tration du plasma du vent solaire dans la magnĂ©tosphĂšre terrestre.The direct access to ionosphere offered by the polar cusps to the solar wind plasma makes it a key region to study the solar wind / magnetosphere interface. It has been chosen to study the nature of the UBF waves and their interactions with the plasma in the most distant part of the polar cusp which the Cluster II data. The detailed study of an event shows that the injections of solar wind plasma are detected in simultaneity with strong electromagnetic UBF activity. The wave analyses highlight the alfvĂ©nic nature of the fluctuations and the mixing of various modes inside a single wave burst. That result is achievable only with a multi-satellite analysis, in this case the k- filtering technique. These results are generalized, showing the importance of the UBF waves in the solar wind plasma penetration into the magnetosphere.PARIS-BIUSJ-ThĂšses (751052125) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF
Importance de la variabilité fonctionnelle intraspécifique des adventices en réponse aux pratiques culturales et aux conditions climatiques
EAGESTADCT1Importance de la variabilité fonctionnelle intraspécifique des adventices en réponse aux pratiques culturales et aux conditions climatiques. Ecologie des Communautés Végétales (ECOVEG 12
Shock deceleration in interplanetary coronal mass ejections (ICMEs) beyond Mercuryâs orbit until one AU
The CDPP propagation tool is used to propagate interplanetary coronal mass ejections (ICMEs) observed at Mercury by MESSENGER to various targets in the inner solar system (VEX, ACE, STEREO-A and B). The deceleration of ICME shock fronts between the orbit of Mercury and 1 AU is studied on the basis of a large dataset. We focus on the interplanetary medium far from the solor corona, to avoid the region where ICME propagation modifications in velocity and direction are the most drastic. Starting with a catalog of 61 ICMEs recorded by MESSENGER, the propagation tool predicts 36 ICME impacts with targets. ICME in situ signatures are investigated close to predicted encounter times based on velocities estimated at MESSENGER and on the default propagation tool velocity (500 km sâ1). ICMEs are observed at the targets in 26 cases and interplanetary shocks (not followed by magnetic ejecta) in two cases. Comparing transit velocities between the Sun and MESSENGER () and between MESSENGER and the targets (), we find an average deceleration of 170 km sâ1 (28 cases). Comparing to the velocities at the targets (v
Tar), average ICME deceleration is about 160 km sâ1 (13 cases). Our results show that the ICME shock deceleration is significant beyond Mercuryâs orbit. ICME shock arrival times are predicted with an average accuracy of about six hours with a standard deviation of eleven hours. Focusing on two ICMEs detected first at MESSENGER and later on by two targets illustrates our results and the variability in ICME propagations. The shock velocity of an ICME observed at MESSENGER, then at VEX and finally at STEREO-B decreases all the way. Predicting arrivals of potentially effective ICMEs is an important space weather issue. The CDPP propagation tool, in association with in situ measurements between the Sun and the Earth, can permit to update alert status of such arrivals
High Impact Practices: A Guide for Teachers of Psychology
Interdisciplinary research indicates what approaches are more likely to help engage students, increase their motivation, develop rapport, and help them learn. In this practical guide for the teachers of psychology, the authors summarize the research in several domains and go a step further to describe practical ways to implement the best practices in face-to-face, hybrid, and online settings. More than a research summarize, and more than just a practical compilation of teaching tips, this book takes a holistic approach to support teachers from the design of their courses to the development of goals, the creation of activities and assignments and finally ends with assessment. The aim is to support both experienced and novice teachers by providing professional development that allows them to give their students the best educational experiences possible