Structure, stability and evolution of 3D Rossby vortices in protoplanetary disks

Large-scale persistent vortices are known to form easily in 2D disks via the Rossby wave or the baroclinic instability. In 3D, however, their formation and stability is a complex issue and still a matter of debate. We study the formation of vortices by the Rossby wave instability in a stratified inviscid disk and describe their three dimensional structure, stability and long term evolution. Numerical simulations are performed using a fully compressible hydrodynamical code based on a second order finite volume method. We assume a perfect gas law and a non-homentropic adiabatic flow.The Rossby wave instability is found to proceed in 3D in a similar way as in 2D. Vortices produced by the instability look like columns of vorticity in the whole disk thickness; the small vertical motions are related to a weak inclination of the vortex axis appearing during the development of the RWI. Vortices with aspect ratios larger than 6 are unaffected by the elliptical instability. They relax to a quasi-steady columnar structure which survives hundred of rotations while slowly migrating inward toward the star at a rate that reduces with the vortex aspect ratio. Vortices with a smaller aspect ratio are by contrast affected by the elliptic instability. Short aspect ratio vortices are completely destroyed in a few orbital periods. Vortices with an intermediate aspect ratio are partially destroyed by the elliptical instability in a region away from the mid-plane where the disk stratification is sufficiently large. Elongated Rossby vortices can survive a large number of orbital periods in protoplanetary disks in the form of vorticity columns. They could play a significant role in the evolution of the gas and the gathering of the solid particles to form planetesimals or planetary cores, a possibility that receives a renewed interest with the recent discovery of a particle trap in the disk of Oph IRS48.Comment: 12 pages, 15 figures, Accepted for publication in A&

Black Holes and Galactic Density Cusps Spherically Symmetric Anisotropic Cusps

Aims: In this paper we study density cusps that may contain central black holes. The actual co-eval self-similar growth would not distinguish between the central object and the surroundings. Methods: To study the environment of a growing black hole we seek descriptions of steady `cusps' that may contain a black hole and that retain at least a memory of self-similarity. We refer to the environment in brief as the `bulge' and on smaller scales, the `halo'. Results: We find simple descriptions of the simulations of collisionless matter by comparing predicted densities, velocity dispersions and distribution functions with the simulations. In some cases central point masses may be included by iteration. We emphasize that the co-eval self-similar growth allows an explanation of the black hole bulge mass correlation between approximately similar collisionless systems. Conclusions: We have derived our results from first principles assuming adiabatic self-similarity and either self-similar virialisation or normal steady virialisation. We conclude that distribution functions that retain a memory of self-similar evolution provide an understanding of collisionless systems. The implied energy relaxation of the collisionless matter is due to the time dependence. Phase mixing relaxation may be enhanced by clump-clump interactions.Comment: 9 pp, 3 figs, accepted by A\&

The 3-fold vertex via stable pairs

The theory of stable pairs in the derived category yields an enumerative geometry of curves in 3-folds. We evaluate the equivariant vertex for stable pairs on toric 3-folds in terms of weighted box counting. In the toric Calabi-Yau case, the result simplifies to a new form of pure box counting. The conjectural equivalence with the DT vertex predicts remarkable identities. The equivariant vertex governs primary insertions in the theory of stable pairs for toric varieties. We consider also the descendent vertex and conjecture the complete rationality of the descendent theory for stable pairs.Comment: Typos fixed. 40 pages, 8 figure

“Digital Punk Rock Spirit:” A Spatial Reorientation of Asian American Diasporic Subcultural Subjectivities

This thesis is about Asian Americans creating and seeking a spaces of belonging, in and between essentialisms of racial, national, ethnic, and cultural borders. Starting from the 1800s, Chinese laborers formed ethnic communities and contested their belonging under the state-sanctioned Chinese Exclusion Acts. State powers as well as transnational forces paved the way for a different racial-urban climate after the 1965 Immigration Acts, which led to the ethnic and class diversification of Asian America and the creation of the “ethnoburb.” As the US developed itself into an automobile state that centered White masculinity, Asian American men formed a unique Asian import subculture that augmented this mainstream consumer culture and created a sense of belonging through associations with Japanese transnational forces. From the Los Angeles ethnoburb of the 2000’s rose the internationally renowned independent music label Zoom Lens. To demonstrate the necessity of transnational approaches and a focus on subcultural currents in the study of Asian American culture and urbanism, as well as to emphasize the spatially reconfiguring powers of the Internet, I argue that Zoom Lens interpolates between a White supremacist suburban racial landscape, a pan-Asian diasporic identity influenced by Japanese otaku subcultures, and an emergent pattern of metaspatialization of community formation enabled by the Internet

Sard Property for the endpoint map on some Carnot groups

In Carnot-Caratheodory or sub-Riemannian geometry, one of the major open problems is whether the conclusions of Sard's theorem holds for the endpoint map, a canonical map from an infinite-dimensional path space to the underlying finite-dimensional manifold. The set of critical values for the endpoint map is also known as abnormal set, being the set of endpoints of abnormal extremals leaving the base point. We prove that a strong version of Sard's property holds for all step-2 Carnot groups and several other classes of Lie groups endowed with left-invariant distributions. Namely, we prove that the abnormal set lies in a proper analytic subvariety. In doing so we examine several characterizations of the abnormal set in the case of Lie groups.Comment: 39 page

Chap. 3 - Aménagement Numérique, Attractivité des Territoires et Développement Durable

Depuis 1995, en France, les média, les industriels de l'Internet, des télécommunications, de l'informatique, de l'électronique et les pouvoirs publics, sont passés du développement de la société de l'information et de l'Internet, de l'émergence éphémère d'une " Nouvelle Economie ", mort-née avec l'éclatement de la " bulle Internet ", à l'apparition de la " fracture numérique " puis à sa résorption avec le décollage de " l'Internet Haut Débit " et le développement durable de " l'Economie numérique". A l'heure de la " haute définition " et du " très haut débit ", les télécommunications et l'informatique fusionnent en " communications électroniques " à la fois pour l'Europe et le régulateur français et l'emploi du concept " d'Aménagement Numérique du Territoire " s'est généralisé dans la sphère publique, des collectivités territoriales aux services de l'Etat notamment la DATAR, en passant par des institutions comme la Caisse des Dépôts et Consignations. Les champs lexicaux techniques et économiques s'entremêlent souvent pour la plus grande incompréhension de chacun d'entre nous alors même que l'on commence à s'interroger sur l'empreinte écologique de cette " Economie Numérique " et son caractère durable . Sur quels concepts peut-on s'appuyer pour comprendre la mutation qui se profile derrière cette agitation " en TIC " et être capable d'agir en conciliant attractivité et durabilité ? Quelle ingénierie territoriale ad hoc peut-on proposer aux décideurs et conseillers soucieux d'articuler local et global à l'heure du " développement durable " des territoires ? Pour répondre à ces questions relevant des champs techniques, économiques et politiques, il est exposé dans une première partie une analyse économique des problématiques relevant de " l'Economie numérique " et de " l'Aménagement Numérique du Territoire ". Puis, dans une seconde partie, en revenant sur les années écoulées depuis 1995, à la lumière d'une participation active de l'auteur , à la conception, à la mise en œuvre et à l'évaluation notamment de politiques publiques en la matière, il est proposé essentiellement au niveau des collectivités territoriales quelques pistes de compréhension et d'intervention au titre de leurs différents champs de compétences réglementaires

VANET Applications: Hot Use Cases

Current challenges of car manufacturers are to make roads safe, to achieve free flowing traffic with few congestions, and to reduce pollution by an effective fuel use. To reach these goals, many improvements are performed in-car, but more and more approaches rely on connected cars with communication capabilities between cars, with an infrastructure, or with IoT devices. Monitoring and coordinating vehicles allow then to compute intelligent ways of transportation. Connected cars have introduced a new way of thinking cars - not only as a mean for a driver to go from A to B, but as smart cars - a user extension like the smartphone today. In this report, we introduce concepts and specific vocabulary in order to classify current innovations or ideas on the emerging topic of smart car. We present a graphical categorization showing this evolution in function of the societal evolution. Different perspectives are adopted: a vehicle-centric view, a vehicle-network view, and a user-centric view; described by simple and complex use-cases and illustrated by a list of emerging and current projects from the academic and industrial worlds. We identified an empty space in innovation between the user and his car: paradoxically even if they are both in interaction, they are separated through different application uses. Future challenge is to interlace social concerns of the user within an intelligent and efficient driving

Implementation and Outcome Evaluation of the Intensive Aftercare Program: Final Report

This Report presents the findings from a 5-year, multisite evaluation of the implementation and outcomes of the Intensive Aftercare Program (IAP), which was sponsored by the Office of Juvenile Justice and Delinquency Prevention (OJJDP). IAP was a major initiative in aftercare programming during the 1990s and has received considerable national attention. It addresses a critical problem facing the nation's juvenile justice system: how to effectively intervene with high-risk, incarcerated juvenile offenders who have demonstrated high recidivism rates and continue to offend as adults

Synthesis and Investigation of Light Responsive Molecules Containing Cyclopropenium Ions

The present thesis describes recent advances in the pursuit of novel light-responsive molecules containing cyclopropenium ions. In an effort to understand the underlying factors regarding the photophysical properties of cyclopropenium ions, emphasis was placed on the previously reported “Janus sponge”, where systematic structural modifications to four individual components of the molecule led to measurable and predictable changes in molar extinction coefficients, quantum yields, and Stokes shifts. Using time-dependent density functional theory calculations, the origin of these trends were traced to internal charge transfer. Additionally, modulating hydrogen bonding between intermolecular, bifurcated, and intramolecular interactions by choice of counterion was used to alter the quantum yield of cyclopropenium ion-containing fluorophores. The basis of this switchability was examined using X-ray diffraction analysis, 1H NMR spectroscopy, density functional theory calculations, and fluorescence spectroscopy. Notably, this work led to the development of the first cyclopropenium ion containing “true” proton sponge. As an extension, light responsive molecules are not isolated to fluorescence. This thesis also outlines the development of the first cyclopropenium ion containing an azo group. Key findings include the fact that cyclopropenium ion containing azo compounds are stable and cyclopropenium ions red-shift the absorbance wavelength in comparison to azobenzene by 75 nm. The synthetic, structural, electronic, and photophysical properties of these compounds are discussed