2,833 research outputs found
An implementation of a compositional approach for verifying generalised nonblocking
Generalised nonblocking is a property of discrete-event systems which verifies liveness. It was introduced to overcome the weaknesses of standard nonblocking. Verifying generalised nonblocking of real-world models often involves exploring state-spaces which will exceed available memory. A compositional verification approach has been developed to achieve verification for models of a much larger size. For this project, we have developed the first implementation for compositionally verifying generalised nonblocking. In addition, we have experimented with the techniques used in compositional verification, and analysed their performance. Our algorithm has successfully verified a large set of industrial-size models, including at least one large model which had not been verified before
Multi-object spectroscopy of the field surrounding PKS 2126-158: Discovery of a z=0.66 galaxy group
The high-redshift radio-loud quasar PKS 2126-158 is found to have a large
number of red galaxies in close apparent proximity. We use the Gemini
Multi-Object Spectrograph (GMOS) on Gemini South to obtain optical spectra for
a large fraction of these sources. We show that there is a group of galaxies at
, coincident with a metal-line absorption system seen in the
quasar's optical spectrum. The multiplexing capabilities of GMOS also allow us
to measure redshifts of many foreground galaxies in the field surrounding the
quasar.
The galaxy group has five confirmed members, and a further four fainter
galaxies are possibly associated. All confirmed members exhibit early-type
galaxy spectra, a rare situation for a Mg II absorbing system. We discuss the
relationship of this group to the absorbing gas, and the possibility of
gravitational lensing of the quasar due to the intervening galaxies.Comment: Monthly Notices of the Royal Astronomical Society, in press. 10
pages, 8 figure
Host Galaxy Contribution to the Colours of `Red' Quasars
We describe an algorithm that measures self-consistently the relative galaxy
contribution in a sample of radio-quasars from their optical spectra alone.
This is based on a spectral fitting method which uses the size of the
characteristic 4000\AA~ feature of elliptical galaxy SEDs. We apply this method
to the Parkes Half-Jansky Flat Spectrum sample of Drinkwater et al. (1997) to
determine whether emission from the host galaxy can significantly contribute to
the very red optical-to-near-infrared colours observed. We find that at around
confidence, most of the reddening in unresolved (mostly quasar-like)
sources is unlikely to be due to contamination by a red stellar component.Comment: 11 pages, 11 figures. Accepted for Publication in Monthly Notices of
the Royal Astronomical Societ
Pion electromagnetic form factor from full lattice QCD
We present preliminary results from the first calculation of the pion electromagnetic form factor at physical light quark masses. This form factor parameterises the deviations from the behaviour of a point-like particle when a photon hits the pion. These deviations result from the internal structure of the pion and can thus be calculated in QCD. We use three sets (different lattice spacings) of n_f=2+1+1 lattice configurations generated by the MILC collaboration. The Highly Improved Staggered Quark formalism (HISQ) is used for all of the sea and valence quarks. Using lattice configurations with u/d quark masses very close to the physical value is an advantage, as we avoid the chiral extrapolation. We study the shape of the vector (f_+) form factor in the q^2 range from 0 to -0.12 GeV^2 and extract the mean square radius, <r^2_v>. The shape of the vector form factor and the resulting radius is compared with experiment
Three religious orientations and five personality factors : an exploratory study among adults in England
In order to explore the power of the five factor model of personality to explain individual differences recorded on measures of the three religious orientations, a sample of 198 adults in England completed established measures of the three religious orientations (intrinsic, extrinsic, and quest) and the big five personality factors (neuroticism, extraversion, openness, agreeableness, and conscientiousness). The data demonstrated that individual differences in the three religious orientations were largely independent of the five personality factors, apart from a significant positive correlation between intrinsic religiosity and agreeableness. These findings support Piedmontâs contention that religiosity is largely independent of personality when personality is operationalised in terms of the big five factors
Detecting Quantum Critical Points using Bipartite Fluctuations
We show that the concept of bipartite fluctuations F provides a very
efficient tool to detect quantum phase transitions in strongly correlated
systems. Using state of the art numerical techniques complemented with
analytical arguments, we investigate paradigmatic examples for both quantum
spins and bosons. As compared to the von Neumann entanglement entropy, we
observe that F allows to find quantum critical points with a much better
accuracy in one dimension. We further demonstrate that F can be successfully
applied to the detection of quantum criticality in higher dimensions with no
prior knowledge of the universality class of the transition. Promising
approaches to experimentally access fluctuations are discussed for quantum
antiferromagnets and cold gases.Comment: 5 pages, 6 figures + suppl. material; final version, Phys. Rev. Lett.
(in press
General Relation between Entanglement and Fluctuations in One Dimension
In one dimension very general results from conformal field theory and exact
calculations for certain quantum spin systems have established universal
scaling properties of the entanglement entropy between two parts of a critical
system. Using both analytical and numerical methods, we show that if particle
number or spin is conserved, fluctuations in a subsystem obey identical scaling
as a function of subsystem size, suggesting that fluctuations are a useful
quantity for determining the scaling of entanglement, especially in higher
dimensions. We investigate the effects of boundaries and subleading corrections
for critical spin and bosonic chains.Comment: 4 pages, 2 figures. Minor changes, references added
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