21 research outputs found
Crystalline silicates and dust processing in the protoplanetary disks of the Taurus young cluster
We characterize the crystalline silicate content and spatial distribution of
small dust grains in a large sample of protoplanetary disks in the
Taurus-Auriga young cluster, using Spitzer Space Telescope mid-infrared
spectra. In turn we use the results to analyze the evolution of structure and
composition of these 1-2 Myr-old disks around Solar- and later-type young
stars, and test the standard models of dust processing which result in the
conversion of originally amorphous dust into minerals. We find strong evidence
of evolution of the dust crystalline mass fraction in parallel with that of the
structure of the disks, in the sense that increasing crystalline mass fraction
is strongly linked to dust settling to the disk midplane. We also confirm that
the crystalline silicates are confined to small radii, r < 10 AU. However, we
see no significant correlation of crystalline mass fraction with stellar mass
or luminosity, stellar accretion rate, disk mass, or disk/star mass ratio, as
would be expected in the standard models of dust processing based upon
photo-evaporation and condensation close to the central star,
accretion-heating-driven annealing at r < 1 AU, or spiral-shock heating at r <
10 AU, with or without effective radial mixing mechanisms. Either another
grain-crystallizing mechanism dominates over these, or another process must be
at work within the disks to erase the correlations they produce. We propose one
of each sort that seem to be worth further investigation, namely X-ray heating
and annealing of dust grains, and modulation of disk structure by
giant-planetary formation and migration.Comment: 116 pages, including 11 figures and 4 table
Tending The Front Porch: Athletics & The University Archive
Presentation from the MARAC conference in Baltimore, MD on October 16–18, 2014. S18 - Varsity Lessons: College Sports Archives and the Human Experienc
Walking the High Wire: The Impact of Campus Tales and Legends on the College or University Archivist
Evidence-Based Chaplaincy Care: Attitudes and Practices in Diverse Healthcare Chaplain Samples
Tenth Scientific Biennial Meeting of the Australasian Virology Society-AVS10 2019
The Australasian Virology Society (AVS) aims to promote, support and advocate for the discipline of virology in the Australasian region. The society was incorporated in 2011 after 10 years operating as the Australian Virology Group (AVG) founded in 2001, coinciding with the inaugural biennial scientific meeting. AVS conferences aim to provide a forum for the dissemination of all aspects of virology, foster collaboration, and encourage participation by students and post-doctoral researchers. The tenth Australasian Virology Society (AVS10) scientific meeting was held on 2-5 December 2019 in Queenstown, New Zealand. This report highlights the latest research presented at the meeting, which included cutting-edge virology presented by our international plenary speakers Ana Fernandez-Sesma and Benjamin tenOever, and keynote Richard Kuhn. AVS10 honoured female pioneers in Australian virology, Lorena Brown and Barbara Coulson. We report outcomes from the AVS10 career development session on "Successfully transitioning from post-doc to lab head", winners of best presentation awards, and the AVS gender equity policy, initiated in 2013. Plans for the 2021 meeting are underway which will celebrate the 20th anniversary of AVS where it all began, in Fraser Island, Queensland, Australia
The Transformation of Social Institutions in the North American Southeast
Corporate institutions, which transformed in the American Southeast over some 14,000 years, include social heterarchies and hierarchies that arose within the institutional contexts of descent groups, ritual sodalities, and social houses. The strategic and tactical actions of competitive and cooperative agents contributed to differing expressions of organizational changes through a variety of forms, including feasting, feuding/warfare, inalienable goods circulation, indebtedness, monumental constructions, mortuary events, processions/rogations, strategic marriages, and additional ritual and social practices. The nexus of social institutions that evolved along these pathways served as a catalyst for social changes, including the ways through which social institutions became transformed. Such social processes inform archaeologists of the agency, organization, and practice of people who not only invented and manipulated cosmologies, ideologies, institutions, and resources to achieve varying degrees of inequality, power, and wealth, but also those who resisted the efforts of aggrandizers. The author’s arguments focus on aristocratic social actions and actors, and the practices that enabled them to gain power and wealth through exclusive and restrictive corporate institutions
Author Correction: The messy death of a multiple star system and the resulting planetary nebula as observed by JWST
International audienc