17,481 research outputs found
Real-time digital modelling in design education and practice
Real-time modelling represents the first thoroughgoing application of the digital realm to architecture and urban design, and as such marks a clear advance on the partial applications that were previously the norm. The authors have pooled their combined expertise in architecture and computer games to adapt the principles and techniques of real-time environments from computer games to designing buildings. The outcome is proprietary software called Cadai, which allows architectural and urban design proposals to be modelled in realistic detail, both externally and internally, and then be "walked" around in their entirety by viewers.
This paper argues that real-time modelling offers three advances on previous forms of 3D digital modelling: it enables digital modelling to be used from the earliest sketch stages of a design project; it allows collective online meetings of the project team inside the evolving design scheme, wherever the participants are in the world; and it enables greater user-participation in decisions about planning schemes, given that anyone familiar with computer game environments can now properly understand and experience architectural and urban design proposals. The paper explains the properties of Cadai and showcases some real-time models built by students at Oxford Brookes University and the University of Westminster, along with the first major commercial real-time model produced in Cadai for a brownfield development proposal in Northern England. Our contention is that real-time modelling will soon become the dominant way that computers operate in architectural and urban design, and will remain so for the foreseeable future
Polarisation-sensitive terahertz detection by multicontact photoconductive receivers
We have developed a terahertz radiation detector that measures both the
amplitude and polarization of the electric field as a function of time. The
device is a three-contact photoconductive receiver designed so that two
orthogonal electric-field components of an arbitrary polarized electromagnetic
wave may be detected simultaneously. The detector was fabricated on Fe+
ion-implanted InP. Polarization-sensitive detection is demonstrated with an
extinction ratio better than 100:1. This type of device will have immediate
application in studies of birefringent and optically active materials in the
far-infrared region of the spectrum.Comment: 3 pages, 3 figure
Quiescent X-Ray/Optical Counterparts of the Black Hole Transient H 1705-250
We report the result of a new Chandra observation of the black hole X-ray
transient H 1705-250 in quiescence. H 1705-250 was barely detected in the new
50 ks Chandra observation. With 5 detected counts, we estimate the source
quiescent luminosity to be Lx~9.1e30 erg/s in the 0.5-10 keV band (adopting a
distance of 8.6 kpc). This value is in line with the quiescent luminosities
found among other black hole X-ray binaries with similar orbital periods. By
using images taken with the Faulkes Telescope North, we derive a refined
position of H 1705-250. We also present the long-term lightcurve of the optical
counterpart from 2006 to 2012, and show evidence for variability in quiescence.Comment: 5 pages, 2 figures; Accepted for publication in MNRA
Early- and late-migrating cranial neural crest cell populations have equivalent developmental potential in vivo
We present the first in vivo study of the long-term fate and potential of early-migrating and late-migrating mesencephalic neural crest cell populations, by performing isochronic and heterochronic quail-to-chick grafts. Both early- and late-migrating populations form melanocytes, neurons, glia, cartilage and bone in isochronic, isotopic chimeras, showing that neither population is lineage-restricted. The early-migrating population distributes both dorsally and ventrally during normal development, while the late-migrating population is confined dorsally and forms much less cartilage and bone. When the late-migrating population is substituted heterochronically for the early-migrating population, it contributes extensively to ventral derivatives such as jaw cartilage and bone. Conversely, when the early-migrating population is substituted heterochronically for the late-migrating population, it no longer contributes to the jaw skeleton and only forms dorsal derivatives. When the late-migrating population is grafted into a late-stage host whose neural crest had previously been ablated, it migrates ventrally into the jaws. Thus, the dorsal fate restriction of the late-migrating mesencephalic neural crest cell population in normal development is due to the presence of earlier-migrating neural crest cells, rather than to any change in the environment or to any intrinsic difference in migratory ability or potential between early- and late-migrating cell populations. These results highlight the plasticity of the neural crest and show that its fate is determined primarily by the environment
How SN Ia host-galaxy properties affect cosmological parameters
We present a systematic study of the relationship between Type Ia Supernova
(SN Ia) properties, and the characteristics of their host galaxies, using a
sample of 581 SNe Ia from the full Sloan Digital Sky Survey II (SDSS-II) SN
Survey. We also investigate the effects of this on the cosmological constraints
derived from SNe~Ia. Compared to previous studies, our sample is larger by a
factor of , and covers a substantially larger redshift range (up to z~0.5),
which is directly applicable to the volume of cosmological interest. We measure
a significant correlation (>5\sigma) between the host-galaxy stellar-mass and
the SN~Ia Hubble Residuals (HR). We find a weak correlation (1.4\sigma) between
the host-galaxy metallicity as measured from emission lines in the spectra, and
the SN~Ia HR. We also find evidence that the slope of the correlation between
host-galaxy mass and HR is -0.11
steeper in lower metallicity galaxies. We test the effects on a cosmological
analysis using both the derived best-fitting correlations between host
parameters and HR, and by allowing an additional free parameter in the fit to
account for host properties which we then marginalize over when determining
cosmological parameters. We see a shift towards more negative values of the
equation of state parameter , along with a shift to lower values of
after applying mass or metallicity corrections. The shift
in cosmological parameters with host-galaxy stellar-mass correction is
consistent with previous studies. We find a best-fitting cosmology of
,
and
(statistical errors only).This work was partly supported by the European Union FP7 programme through ERC grant number 320360.
Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw11
The negative Bogoliubov dispersion in exciton-polariton condensates
Bogoliubov's theory states that self-interaction effects in Bose-Einstein
condensates produce a characteristic linear dispersion at low momenta. One of
the curious features of Bogoliubov's theory is that the new quasiparticles in
the system are linear combinations of creation and destruction operators of the
bosons. In exciton-polariton condensates, this gives the possibility of
directly observing the negative branch of the Bogoliubov dispersion in the
photoluminescence (PL) emission. Here we theoretically examine the PL spectra
of exciton-polariton condensates taking into account of reservoir effects. At
sufficiently high excitation densities, the negative dispersion becomes
visible. We also discuss the possibility for relaxation oscillations to occur
under conditions of strong reservoir coupling. This is found to give a
secondary mechanism for making the negative branch visible
Results from a VLT-ISAAC survey of ices and gas around young stellar objects
General results from a 3-5 micron spectroscopic survey of nearby low-mass
young stellar objects are presented. L and M-band spectra have been obtained of
\~50 low mass embedded young stars using the ISAAC spectrometer mounted on
UT1-Antu at Paranal Observatory. For the first time, a consistent census of the
CO, H2O ices and the minor ice species CH3OH and OCN- and warm CO gas present
around young stars is obtained, using large number statistics and resolving
powers of up to R=10000. The molecular structure of circumstellar CO ices, the
depletion of gaseous CO onto grains in protoplanetary disks, the presence of
hot gas in the inner parts of circumstellar disks and in outflows and infalls
are studied. Furthermore, the importance of scattering effects for the
interpretation of the spectra have been addressed.Comment: To appear in the proceedings of the conference "Chemistry as a
Diagnostic of Star Formation", University of Waterloo, Canada, 21-23 August
200
Randomized controlled trial to determine the impact of probiotic administration on colonization with multidrug-resistant organisms in critically ill patients
This was a randomized controlled pilot study of Lactobacillus rhamnosus GG versus standard of care to prevent gastrointestinal multidrug-resistant organism (MDRO) colonization in ICU patients. Seventy subjects were included in analyses. There were no significant differences in acquisition or loss of any MDROs (p>0.05). There were no probiotic-associated adverse events
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