2,981 research outputs found
High spatial resolution studies of galaxies in the far IR: Observations with the KAO, and the promise of SOFIA
NASA, in collaboration with the West German Science Ministry (BMFT), plans a larger airborne telescope as a successor to the Kuipper Airborne Observatory (KAO) that will achieve these goals. The Stratospheric Observatory for Infrared Astronomy (SOFIA) is entering the final stages of Phase B review with targeted new start early in the next decade. SOFIA is a 2.7 m diameter telescope that is carried in a Boeing 747SP. In addition to having 3 times the spatial resolution of the KAO, and 10 times the light gathering power, it will incorporate improvements over the KAO in lower optical emissivity and better telescope tracking stability. The thin primary mirror will equilibrate quickly to ambient temperature at an altitude which, accompanied by airflow improvements across the telescope cavity, will result in better image quality. The sensitivity of SOFIA will allow us to see a large number of typical bright galactic HII regions in local group galaxies. The spatial resolution of 8 seconds (full width half maximum Airy disk) at 100 microns will allow these regions to be measured independently, if they are distributed similarly to those in our own galaxy. At this spatial resolution, the disks of normal galaxies will be easily resolved out to distances of several hundred Mpc. This portion of space includes many of the superluminous galaxies discovered by the Infrared Astronomy Satellite (IRAS), and this spatial scale is relevant for studies of the morphology of regions of interaction among the majority of these galaxies that are members of colliding pairs
Universal finitary codes with exponential tails
In 1977, Keane and Smorodinsky showed that there exists a finitary
homomorphism from any finite-alphabet Bernoulli process to any other
finite-alphabet Bernoulli process of strictly lower entropy. In 1996, Serafin
proved the existence of a finitary homomorphism with finite expected coding
length. In this paper, we construct such a homomorphism in which the coding
length has exponential tails. Our construction is source-universal, in the
sense that it does not use any information on the source distribution other
than the alphabet size and a bound on the entropy gap between the source and
target distributions. We also indicate how our methods can be extended to prove
a source-specific version of the result for Markov chains.Comment: 33 page
Commensurations of the Johnson kernel
Let K be the subgroup of the extended mapping class group, Mod(S), generated
by Dehn twists about separating curves. Assuming that S is a closed, orientable
surface of genus at least 4, we confirm a conjecture of Farb that Comm(K),
Aut(K) and Mod(S) are all isomorphic. More generally, we show that any
injection of a finite index subgroup of K into the Torelli group I of S is
induced by a homeomorphism. In particular, this proves that K is co-Hopfian and
is characteristic in I. Further, we recover the result of Farb and Ivanov that
any injection of a finite index subgroup of I into I is induced by a
homeomorphism. Our method is to reformulate these group theoretic statements in
terms of maps of curve complexes.Comment: Published by Geometry and Topology at
http://www.maths.warwick.ac.uk/gt/GTVol8/paper37.abs.htm
High spatial resolution 100 micron observations of the M83 bar
A program of high spatial resolution far-infrared observations of galaxies using the Kuiper Airborne Observatory (KAO), was conducted to better understand the role of star formation, the general interstellar radiation field, and non-thermal activity in powering the prodigious far-infrared luminosities seen in spiral and interacting galaxies. Here, researchers present observations of the central region of the well-known barred spiral M83 (NGC 5236). The resultant channel 3 scans for M83 and IRC + 10216, after co-addition and smoothing, are shown. These data show that M83 is extended at 100 microns compared to a point source. A simple Gaussian deconvolution of the M83 data with the point source profile from IRC+10216 gives a full width half maximum (FWHM) of about 19 seconds for M83. By comparison with IRC+10216, researchers obtain a flux for the unresolved component in M83 of about 110 Jy. This is about 1/6 the total flux for M83 (Rice et al. 1988) and about 1/2 the PSC flux. The M83 and IRC+10216 profiles in the cross-scan direction (SE-NW) were also compared, and show that M83 is extended in this direction as well, with a width of about 18 seconds. A comparison of the different channel profiles for M83 and IRC+10216 shows that there is an asymmetry in the M83 data, in that the maximum in the profiles shifts from southeast to northwest as channel number increases. This corresponds to the extension in the bar seen in the CO data. Thus the far-infrared emission in the central region of M83 tends to trace the CO bar. The new 100 micron data is also compared with previous H alpha observations from the literature, to determine how well the far-infrared traces the stellar structure, the star formation as measured by H alpha, and the optical colors
Getting Real: Interactive Fieldwork
The Getting Real: Interactive Fieldwork walking tour is one of the CCW Graduate School's Year of Resilience events. It explores what happens when research and teaching take place outside the academic institution through engaging directly with a situation, place or space. How might this direct experience engage with our understandings of embodied (physically understood) proximity, and through this allow us to empathise with diverse situations. Taking ‘fieldwork’, i.e. when we leave our (enclosed) laboratories, be they the overall college or studios/workshops as a starting point, the walking tour invites us to makes connections with each other and the world beyond Wimbledon College of Arts.
The day is led by artists Heather Ackroyd and Dan Harvey - Heather also has a background in theatre and performance, so it is an opportunity to talk across the Fine Art and Theatre programmes and levels. They have innovative insights into both research techniques and making processes, which in turn connects with their resilient approach to living and engaging with space and place. They have worked on many occasions with Cape Farewell, who are currently in residence at the CCW Graduate School
Dynamical Moving Mirrors and Black Holes
A simple quantum mechanical model of free scalar fields interacting with
a dynamical moving mirror is formulated and shown to be equivalent to
two-dimensional dilaton gravity. We derive the semi-classical dynamics of this
system, by including the back reaction due to the quantum radiation. We develop
a hamiltonian formalism that describes the time evolution as seen by an
asymptotic observer, and write a scattering equation that relates the
in-falling and out-going modes at low energies. At higher incoming energy flux,
however, the classical matter-mirror dynamics becomes unstable and the mirror
runs off to infinity. This instability provides a useful paradigm for black
hole formation and introduces an analogous information paradox. Finally, we
propose a new possible mechanism for restoring the stability in the
super-critical situation, while preserving quantum coherence. This mechanism is
based on the notion of an effective time evolution, that takes into account the
quantum mechanical effect of the measurement of the Hawking radiation on the
state of the infalling matter.Comment: 37 pages, 5 figures attached, epsf, harvmac, PUPT-143
The new-generation antipsychotics -integrating the neuropathology and pharmacology of schizophrenia
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Strengthening the global system of protected areas post-2020: A perspective from the IUCN World Commission on Protected Areas
Protected areas are the cornerstones of biodiversity conservation and have never been more relevant than at the present time when the world is facing both a biodiversity and a climate change crisis. The International Union for Conservation of Nature (IUCN) World Commission on Protected Areas (WCPA) has been helping to set global standards and best practice guidelines in protected area planning and management for 60 years. Following this guidance, many countries have made significant progress toward their Aichi Target 11 commitments under the Convention on Biological Diversity (CBD). The global community will be coming together at the 15th Conference of the Parties of the CBD to set new biodiversity conservation targets for the next decade, as milestones to 2050 and a vision of “a world living in harmony with nature.” This paper lays out the WCPA perspective on priorities for supporting effective protected and conserved areas for the post-2020 era
System-level intersectoral linkages between the mental health and non-clinical support sectors: a qualitative systematic review
Objectives: Concerns about fragmented mental health service delivery persist, particularly for people with severe and persistent mental illness. The objective was to review evidence regarding outcomes attributed to system-level intersectoral linkages involving mental health services and non-clinical support services, and to identify barriers and facilitators to the intersectoral linkage process
Chiasma
Newspaper reporting on events at the Boston University School of Medicine in the 1960s
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