On the orbital evolution of a pair of giant planets in mean motion resonance

Pairs of extrasolar giant planets in a mean motion commensurability are common with 2:1 resonance occurring most frequently. Disc-planet interaction provides a mechanism for their origin. However, the time scale on which this could operate in particular cases is unclear. We perform 2D and 3D numerical simulations of pairs of giant planets in a protoplanetary disc as they form and maintain a mean motion commensurability. We consider systems with current parameters similar to those of HD 155358, 24 Sextantis and HD 60532, and disc models of varying mass, decreasing mass corresponding to increasing age. For the lowest mass discs, systems with planets in the Jovian mass range migrate inwards maintaining a 2:1 commensurability. Systems with the inner planet currently at around 1 au from the central star could have originated at a few au and migrated inwards on a time scale comparable to protoplanetary disc lifetimes. Systems of larger mass planets such as HD 60532 attain 3:1 resonance as observed. For a given mass accretion rate, results are insensitive to the disc model for the range of viscosity prescriptions adopted, there being good agreement between 2D and 3D simulations. However, in a higher mass disc a pair of Jovian mass planets passes through 2:1 resonance before attaining a temporary phase lasting a few thousand orbits in an unstable 5:3 resonance prior to undergoing a scattering. Thus finding systems in this commensurability is unlikely.ENS CachanThis is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw157

A spatial scan statistic for zero-inflated Poisson process

The scan statistic is widely used in spatial cluster detection applications of inhomogeneous Poisson processes. However, real data may present substantial departure from the underlying Poisson process. One of the possible departures has to do with zero excess. Some studies point out that when applied to data with excess zeros, the spatial scan statistic may produce biased inferences. In this work, we develop a closed-form scan statistic for cluster detection of spatial zero-inflated count data. We apply our methodology to simulated and real data. Our simulations revealed that the Scan-Poisson statistic steadily deteriorates as the number of zeros increases, producing biased inferences. On the other hand, our proposed Scan-ZIP and Scan-ZIP+EM statistics are, most of the time, either superior or comparable to the Scan-Poisson statistic

Développement des lacs proglaciaires et déglaciation des hauts bassins des Rivières au Saumon et Chaudière, sud du Québec

Les études antérieures sur le Quaternaire du sud du Québec mettent en évidence un modèle général de déglaciation basé sur la position des moraines principales. Notre étude, axée sur une logique des formes et des dépôts, détaille l'évolution de la récession glaciaire et le développement des lacs retenus par le front de l'inlandsis, dans une sous-région de l'Estrie. Le drainage proglaciaire a évolué en quatre systèmes principaux : le système des « étangs Frontaliers » (1), composés de petits lacs qui se sont d'abord vidés de façon diffuse vers la Nouvelle-Angleterre, avant que le drainage ne se concentre vers le fleuve Kennebec (2), puis vers le fleuve Connecticut (3), pour finalement se faire vers le lac proglaciaire Memphrémagog (4). L'évolution du retrait glaciaire commence par l'apparition de nunataks, résultant de l'amincissement de l'inlandsis. L'allure du front reflète dès lors la configuration du relief sous-jacent qui influence directement le mode de fusion de la glace. Le retrait de la glace est relativement plus rapide dans les vallées orientées dans le sens de la déglaciation et il existe une corrélation inverse entre la pente du relief et la vitesse de recul de l'inlandsis.The general pattern of de-glaciation in southern Québec in previous studies is based primarily on the location of the principal moraines. This article presents the detailed evolution of proglacial lakes and the retreat of the ice front based upon a study of the geomorphology and Quaternary deposits in a subregion of the Eastern Townships. Four main systems of proglacial drainage have been mapped: the "Étangs Frontaliers" (1) drained through various cols toward New England before the drainage concentration first in the Kennebec River (2) then in the Connecticut River (3), and finally into proglacial Lake Memphrémagog (4). The evolution of the ice front position began with the development of nunataks, resulting from the thinning of the ice-sheet and its shape reflected the underlying topography. The local retreat was faster in valleys oriented in the direction of the déglaciation and, in general, there is an inverse correlation between slope line and rate of glacier retreat.Die frùheren Forschungsarbeiten ùber das Quartâr im Sùden von Québec zeigen ein allgemeines Muster der Enteisung, das sich auf die Lage der wichtigsten Morànen stùtzt. Dieser Artikel zeigt die genaue Entwicklung proglazialer Seen und den Rùckzug der Eisfront, gestùtzt auf eine Erforschung der Géomorphologie und Quartâr Ablagerungen in einer Subregion der Cantons de l'Est. Vier Hauptsysteme fur proglaziale Entwàsserung wurden kartographiert: "Étangs Frontaliers" (1) entwâssert durch verschiedene Joche nach New England hin, bevor eine Entwàsserungskonzentration zuerst im Kennebek Fluss (2) dann in den Connecticut Fluss (3), und schliesslich in den proglazial See Memphrémagog (4) geschieht. Die Evolution der Eisfrontposition begann mit der Entwicklung von Nunataken, als Résultat von der Verdùnnung der Eisdecke, und ihre Form spiegelte die unterliegende Topographie wider. Der ôrtliche Rùckzug war in den Tàlern, die mit der Richtung der Enteisung ùbereinstimmten schneller, und im Allgemeinen gibt es eine umgekehrte Korelation zwischen Hanglinie und der Geschwindigkeit des Gletscher Rùckzuges

Évolution des lacs proglaciaires et déglaciation du Haut Saint-François, sud du Québec

Pendant la dernière déglaciation, un front glaciaire actif se retire vers l'amont de la haute vallée de la rivière Saint-François et vers l'aval de celle de la rivière au Saumon. Dans la vallée de la rivière Saint-François, le front glaciaire, qui recule exceptionnellement vers le nord-est, est en contact avec les eaux du lac proglaciaire Memphrémagog, alors barré dans la partie aval du bassin par la masse principale de l'indandsis. Le lobe ainsi confiné dans la vallée de la rivière Saint-François endigue, dans le bassin de la rivière au Saumon, un lac proglaciaire latéral contrôlé par des cols et des chenaux le long du front. La récession du lobe est marquée par des récurrences locales qui ont mis en place des moraines à East-Angus et à Weedon. Après le retrait du lobe, au-delà du niveau du lac proglaciaire Memphrémagog, un lac de barrage morainique persiste au contact de la glace, dans la région de Weedon.The déglaciation pattern of southern Québec, defined by previous studies, is based up on the retreat of an active ice front toward the northwest. However in the Saint-François River valley, upstream from Sherbrooke, glacial recession was toward the north and northeast. In the Saint-François River valley, the ice retreated headward while in the Saumon River valley it retreated down stream. The ice front in the upper Saint-François River was in contact with proglacial Lake Memphrémagog which was dammed by the main mass of the ice sheet in the lower part of the drainage basin. The lake in the upper Saint-François River also dammed a lateral proglacial lake in the Saumon River, which was controlled by cols to the southeast of the lake. Retreat of the ice front was punctuated by local readvances during which the East Angus and Weedon Moraines were formed. Once the margin had retreated to the northeast, above the level of proglacial Lake Memphrémagog, a moraine dammed glacial lake formed in the Weedon area.Seit der letzten Deglaziation zieht sich eine aktive Eisfront flussaufwàrts in das Hochtal des St François Flusses und flussabwârts in das des Saumon Flusses zurùck. Im TaI des St François Flusses ist die Eisfront, die sich hier Ausnahmsweise nach dem Nordosten zurùckzieht, im Kontakt mit den Gewàssern des proglazial. Sees Memphrémagog, der im flussabwârts liegenden Teil des Beckens durch die Hauptmasse des Inlandeises gesperrt ist. Der See im oberen St François Fluss sperrte auch einen seitlichen proglazial See im Saumon Fluss, welcher von Jochen im Sùdosten des Sees kontrolliert wurde. Der Rùckzug des Lappens ist durch lokale Vorschùbe gekennzeichnet, die die Moranen von East Angus und Weedon geschafft haben. Nach dem Rùckzug des Lappens ùber das Niveau des proglazialen Memphrémagog Sees hinaug, besteht noch ein Morànen Stausee, am Eiskontakt in der Region von Weedon

Wave propagation in semiconvective regions of giant planets

Recent observations of Jupiter and Saturn suggest that heavy elements may be diluted in the gaseous envelope, providing a compositional gradient that could stabilise ordinary convection and produce a stably-stratified layer near the core of these planets. This region could consist of semi-convective layers with a staircase-like density profile, which have multiple convective zones separated by thin stably-stratified interfaces, as a result of double-diffusive convection. These layers could have important effects on wave propagation and tidal dissipation that have not been fully explored. We analyse the effects of these layers on the propagation and transmission of internal waves within giant planets, extending prior work in a local Cartesian model. We adopt a simplified global Boussinesq planetary model in which we explore the internal waves in a non-rotating spherical body. We begin by studying the free modes of a region containing semi-convective layers. We then analyse the transmission of internal waves through such a region. The free modes depend strongly on the staircase properties, and consist of modes with both internal and interfacial gravity wave-like behaviour. We determine the frequency shifts of these waves as a function of the number of steps to explore their potential to probe planetary internal structures. We also find that wave transmission is strongly affected by the presence of a staircase. Very large-wavelength waves are transmitted efficiently, but small-scale waves are only transmitted if they are resonant with one of the free modes. The effective size of the core is therefore larger for non-resonant modes

Metal-Polymer Nanoconjugates Application in Cancer Imaging and Therapy

Metallic-based nanoparticles present a unique set of physicochemical properties that support their application in different fields, such as electronics, medical diagnostics, and therapeutics. Particularly, in cancer therapy, the plasmonic resonance, magnetic behavior, X-ray attenuation, and radical oxygen species generation capacity displayed by metallic nanoparticles make them highly promising theragnostic solutions. Nevertheless, metallic-based nanoparticles are often associated with some toxicological issues, lack of colloidal stability, and establishment of off-target interactions. Therefore, researchers have been exploiting the combination of metallic nanoparticles with other materials, inorganic (e.g., silica) and/or organic (e.g., polymers). In terms of biological performance, metalpolymer conjugation can be advantageous for improving biocompatibility, colloidal stability, and tumor specificity. In this review, the application of metallic-polymer nanoconjugates/nanohybrids as a multifunctional all-in-one solution for cancer therapy will be summarized, focusing on the physicochemical properties that make metallic nanomaterials capable of acting as imaging and/or therapeutic agents. Then, an overview of the main advantages of metal-polymer conjugation as well as the most common structural arrangements will be provided. Moreover, the application of metallic-polymer nanoconjugates/nanohybrids made of gold, iron, copper, and other metals in cancer therapy will be discussed, in addition to an outlook of the current solution in clinical trials.info:eu-repo/semantics/publishedVersio