A ring system detected around the Centaur (10199) Chariklo

Until now, rings have been detected in the Solar System exclusively around the four giant planets. Here we report the discovery of the rst minor-body ring system around the Centaur object (10199) Chariklo, a body with equivalent radius 124±9 km. A multi-chord stellar occultation revealed the presence of two dense rings around Chariklo, with widths of about 7 km and 3 km, optical depths 0.4 and 0.06, and orbital radii 391 and 405 km, respectively. The present orientation of the ring is consistent with an edge-on geometry in 2008, thus providing a simple explanation for the dimming of Chariklo's system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partially composed of water ice. These rings may be the remnants of a debris disk, which were possibly con ned by embedded kilometre-sized satellites

Comportement alimentaire d'Euseius stipulatus et Typhlodromus phialatus sur l'acarien rouge de l'oranger Panonychus citri [Acari: Phytoseffdae, Tetranychidae]

[EN] Observations were made on the feeding behavior of the two main phytoseiid species in Spanish Citrus orchards,Euseius stipulatus (Athias-Henriot) andTyphlodromus phialatus Athias-henriot. The experiences were carried out by rearing the predatory mites on excised orange leaves, and always with an excess of the prey the Citrus Red Mite (=CRM)Panonychus citri (McGregor). In experiments with all stages of CRM, the number of prey killed per hour was 5.12 and 2.00, the percentage of successful attacks, 58% and 21%, and the mean time spent feeding on each prey was 5.1 and 12.2 minutes for starving females ofE. stipulatus andT. phialatus respectively.E. stipulatus feeds on all stages of the prey except eggs, andT. philatus, on all stages, except males. Both species attack much less successfully females ofP. citri rather than immatures. In experiments with adult females and eggs ofP. citri as prey, the mean number of prey killed daily was 4.51 females forE. stipulatus, and 2.01 females and 2.12 eggs forT. philatus. Considering this killing rate and the number of eggs laid by the predators in the same period, it can be concluded thatE. stipulatus consumes only 30% of the content of the preys killed, whereasT. philatus consumes a percentage of prey variable between individuals and ranging from 40% to 100%. These differences in feeding behavior between the two species could partly explain differences in their efficiency as biocontrol agents ofP. citri observed in the field.[FR] On a étudié le comportement alimentaire des deux principales espèces de phytoséiides présents dans les vergers de Citrus en Espagne,Euseius stipulatus (Athias-Henriot) etTyphlodromus phialatus Athias-Henriot. Les expériences ont été menées en élevant l'acarien prédateur sur feuilles d'oranger, avec un excès de sa proiePanonychus citri (McGregor). Dans les essais avec tous les stades de l'acarien rouge, le nombre moyen de proies tuées par heure est de 5.12 et 2.00, le pourcentage d'attaques réussies de 58% et 21% et le temps moyen passé à se nourrir sur chaque proie de 5.1 min et 12.2 min respectivement pour les femelles d'E. stipulatus etT. phialatus. Tous les stades de développement, excepté le stade œuf, peuvent être consommés parE. stipulatus tandis queT. phialatus se nourrit de tous les stades, à l'exception des mes. Chez les deux espèces, les femelles deP. citri sont attaquées avec moins de succès que les immatures. Lorsque les proies sont constituées de femelles adultes ou d'œufs deP. citri le nombre moyen de proies tuées quotidiennement est de 4.51 femelles pourE. stipulatus, et de 2.01 femelles et 2.12 œufs pourT. phialatus. Si l'on considère le nombre d'œufs pondus par les acariens prédateurs durant la même période,E. stipulatus ingère seulement 30% du total des proies tuées, alors queT. phialatus ingère un nombre de proies variable selon les individus, allant de 40 à 100%. Ces différences d'alimentation chez ces deux espèces pourraient expliquer en partie leurs différences d'efficacité observées sur le terrain, en tant qu'agents de lutte biologique.This work was funded by a grant from Comision Asesora de Investigación Cientifica y Técnica (0577/81).Ferragut Pérez, FJ.; Laborda Cenjor, R.; Costa Comelles, J.; García Mari, F. (1992). Feeding behavior of Euseius stipulatus and Typhlodromus phialatus on the Citrus Red Mite Panonychus citri (Acari: Phytoseiidae, Tetranychidae). ENTOMOPHAGA. 37(4):537-543. https://doi.org/10.1007/BF02372323S537543374Badii, M. H. andMcMurtry, J. A. — 1984. Feeding behavior of some phytoseiid predators on the broad mitePolyphagotarsonemus latus (Acari: Phytoseiidae: Tarsonemidae). —Entomophaga, 29, 49–53.Blommers, L., Lobbes, P., Vink, P. andWegdam, F. — 1977. Studies on the response ofAmblyseius bibens (Acarina: Phytoseiidae) to conditions to prey scarcity. —Entomophaga, 22: 247–258.De Moraes, G. J. andMcMurtry, J. A. — 1981. Biology ofAmblyseius citrifolius (Denmark and Muma) (Acarina: Phytoseiidae). —Hilgardia, 49: 1–29.Ferragut, F., García-Marí, F., Costa-Comelles, J. andLaborda, R. — 1987. Influence of food and temperature on development and oviposition ofEuseius stipulatus (Athias-Henriot) andTyphlodromus phialatus Athias-Henriot (Acari: Phytoseiidae). —Exp. Appl. Acarol., 3: 317–329.Friese, D. D. andGilstrap, F. E. — 1982. Influence of prey availability on reproduction and prey consumption ofPhytoseiulus persimilis, Amblyseius californicus andMetaseiulus occidentalis (Acarina: Phytoseiidae). —Internat. J. Acarol., vol. 8, n0 2: 85–89.García-Marí, F., Ferragut, F., Marzal, C., Costa-Comelles, J. andLaborda, R. — 1986. Acaros que viven en las hojas de los citricos españoles. —Inv. Agr. Prod. Prot. Vegetal, vol. 1 (2): 61–92.Hoyt, S. C. — 1970. Effect of short feeding periods byMetaseiulus occidentalis on fecundity and mortality ofTetranychus mcdanieli. —Ann. Entomol. Soc. Am., 63: 1382–1384.Sabelis, M. W. — 1985. Predation on spider mites. In Spider Mites. Their Biology, Natural Enemies and Control. (Helle andSabelis ed.). — Elsevier, Amsterdam Vol. 1B, pp. 103–129.Sandness, J. N. andMcMurtry, J. A. — 1970. Functional response of three species of Phytoseiidae (Acarina) to prey density.Can. Ent., 102: 692–704.Sandness, J. N. andMcMurtry, J. A. — 1972. Prey consumption behavior ofAmblyseius largoensis in relation to hunger. —Can. Ent., 104: 461–470.Tanigoshi, L. K. — 1981. Advances in knowledge of the biology of the Phytoseiidae.In: Recent advances in knowledge of the Phytoseiidae (M. A. Hoy ed.). Univ. California. pp. 1–22.Van de Vrie, M. — 1974. Studies on prey-predator interactions betweenPanonychus ulmi andTyphlodromus (A.)potentillae (Acarina: Tetranychidae, Phytoseiidae) on apple in the Netherlands. — Proceedings FAO Conference on Ecology in relation to pest control. Rome, pp. 145–160

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Surface and borehole ground-penetrating-radar developments

During the past 80 years, ground-penetrating radar (GPR) has evolved from a skeptically received glacier sounder to a full multicomponent 3D volume-imaging and characterization device. The tool can be calibrated to allow for quantitative estimates of physical properties such as water content. Because of its high resolution, GPR is a valuable tool for quantifying subsurface heterogeneity, and its ability to see nonmetallic and metallic objects makes it a useful mapping tool to detect, localize, and characterize buried objects. No tool solves all problems; so to determine whether GPR is appropriate for a given problem, studying the reasons for failure can provide an understanding of the basics, which in turn can help determine whether GPR is appropriate for a given problem. We discuss the specific aspects of borehole radar and describe recent developments to become more sensitiveto orientation and to exploit the supplementary information in different components in polarimetric uses of radar data. Multicomponent GPR data contain more diverse geometric information than single-channel data, and this is exploited in developed dedicated imaging algorithms. The evolution of these imaging schemes is discussed for ground-coupled and air-coupled antennas. For air-coupled antennas, the measured radiated wavefield can be used as the basis for the wavefield extrapolator in linear-inversion schemes with an imaging condition, which eliminates the source-time function and corrects for the measured radiation pattern. A handheld GPR system coupled with a metal detector is ready for routine use in mine fields. Recent advances in modeling, tomography, and full-waveform inversion, as well as Green's function extraction through correlation and deconvolution, show much promise in this field.Geoscience & EngineeringCivil Engineering and Geoscience

Characterization of the Ejecta from the NASA/DART Impact on Dimorphos: Observations and Monte Carlo Models

The NASA Double Asteroid Redirection Test (DART) spacecraft successfully crashed on Dimorphos, the secondary component of the binary (65803) Didymos system. Following the impact, a large dust cloud was released, and a long-lasting dust tail developed. We have extensively monitored the dust tail from the ground and the Hubble Space Telescope. We provide a characterization of the ejecta dust properties, i.e., particle size distribution and ejection speeds, ejection geometric parameters, and mass, by combining both observational data sets and using Monte Carlo models of the observed dust tail. The size distribution function that best fits the imaging data is a broken power law having a power index of -2.5 for particles of r & LE; 3 mm and -3.7 for larger particles. The particles range in size from 1 & mu;m up to 5 cm. The ejecta is characterized by two components, depending on velocity and ejection direction. The northern component of the double tail, observed since 2022 October 8, might be associated with a secondary ejection event from impacting debris on Didymos, although is also possible that this feature results from the binary system dynamics alone. The lower limit to the total dust mass ejected is estimated at & SIM;6 x 10(6) kg, half of this mass being ejected to interplanetary space