39,030 research outputs found
Foodborne disease outbreaks in Australia 2001-2009
BACKGROUND: Analysis of surveillance data from foodborne disease outbreaks can help identify high-risk aetiological agents, food vehicles and settings. This information may help prevent future illness by informing the development of public health policy
Quantum Preferred Frame: Does It Really Exist?
The idea of the preferred frame as a remedy for difficulties of the
relativistic quantum mechanics in description of the non-local quantum
phenomena was undertaken by such physicists as J. S. Bell and D. Bohm. The
possibility of the existence of preferred frame was also seriously treated by
P. A. M. Dirac. In this paper, we propose an Einstein-Podolsky-Rosen-type
experiment for testing the possible existence of a quantum preferred frame. Our
analysis suggests that to verify whether a preferred frame of reference in the
quantum world exists it is enough to perform an EPR type experiment with pair
of observers staying in the same inertial frame and with use of the massive EPR
pair of spin one-half or spin one particles.Comment: 5 pp., 6 fig
Environmental dependence of AGN activity in the supercluster A901/2
We present XMM data for the supercluster A901/2, at z ~ 0.17, which is
combined with deep imaging and 17-band photometric redshifts (from the COMBO-17
survey), 2dF spectra and Spitzer 24um data, to identify AGN in the
supercluster. The 90ksec XMM image contains 139 point sources, of which 11 are
identified as supercluster AGN with L_X(0.5-7.5keV) > 1.7x10^41 erg/cm2/s. The
host galaxies have M_R < -20 and only 2 of 8 sources with spectra could have
been identified as AGN by the detected optical emission lines. Using a large
sample of 795 supercluster galaxies we define control samples of massive
galaxies with no detected AGN. The local environments of the AGN and control
samples differ at >98 per cent significance. The AGN host galaxies lie
predominantly in areas of moderate projected galaxy density and with more local
blue galaxies than the control sample, with the exception of one very bright
Type I AGN very near the centre of a cluster. These environments are similar
to, but not limited to, cluster outskirts and blue groups. Despite the large
number of potential host galaxies, no AGN are found in regions with the highest
galaxy density (excluding some cluster cores where emission from the ICM
obscures moderate luminosity AGN). AGN are also absent from the areas with
lowest galaxy density. We conclude that the prevalence of cluster AGN is linked
to their environment.Comment: 20 pages, 15 figures. MNRAS accepted. Version with full resolution
figures, including Figure 14, is available at
http://www.sc.eso.org/~rgilmour
Proposed direct test of a certain type of noncontextuality in quantum mechanics
The noncontextuality of quantum mechanics can be directly tested by measuring
two entangled particles with more than two outcomes per particle. The two
associated contexts are "interlinked" by common observables.Comment: 9 pages 2 figure
Gravitational lens candidates in the E-CDFS
We report ten lens candidates in the E-CDFS from the GEMS survey. Nine of the
systems are new detections and only one of the candidates is a known lens
system. For the most promising five systems including the known lens system, we
present results from preliminary lens mass modelling, which tests if the
candidates are plausible lens systems. Photometric redshifts of the candidate
lens galaxies are obtained from the COMBO-17 galaxy catalog. Stellar masses of
the candidate lens galaxies within the Einstein radius are obtained by using
the -band luminosity and the color-based stellar mass-to-light ratios.
As expected, the lensing masses are found to be larger than the stellar masses
of the candidate lens galaxies. These candidates have similar dark matter
fractions as compared to lenses in SLACS and COSMOS. They also roughly follow
the halo mass-stellar mass relation predicted by the subhalo abundance matching
technique. One of the candidate lens galaxies qualifies as a LIRG and may not
be a true lens because the arc-like feature in the system is likely to be an
active region of star formation in the candidate lens galaxy. Amongst the five
best candidates, one is a confirmed lens system, one is a likely lens system,
two are less likely to be lenses and the status of one of the candidates is
ambiguous. Spectroscopic follow-up of these systems is still required to
confirm lensing and/or for more accurate determination of the lens masses and
mass density profiles.Comment: 12 pages, 5 figures, 3 tables, ApJ accepte
Constructing quantum games from non-factorizable joint probabilities
A probabilistic framework is developed that gives a unifying perspective on
both the classical and the quantum games. We suggest exploiting peculiar
probabilities involved in Einstein-Podolsky-Rosen (EPR) experiments to
construct quantum games. In our framework a game attains classical
interpretation when joint probabilities are factorizable and a quantum game
corresponds when these probabilities cannot be factorized. We analyze how
non-factorizability changes Nash equilibria in two-player games while
considering the games of Prisoner's Dilemma, Stag Hunt, and Chicken. In this
framework we find that for the game of Prisoner's Dilemma even non-factorizable
EPR joint probabilities cannot be helpful to escape from the classical outcome
of the game. For a particular version of the Chicken game, however, we find
that the two non-factorizable sets of joint probabilities, that maximally
violates the Clauser-Holt-Shimony-Horne (CHSH) sum of correlations, indeed
result in new Nash equilibria.Comment: Revised in light of referee's comments, submitted to Physical Review
Life on a low income in austere times
Following the ‘credit crunch’ 2007-2008, the UK entered the deepest recessionary conditions in living memory. As the liquidity from the financial services sector came to an abrupt halt, the investment ‘life blood’ of the economy in short supply, numerous companies, including long established high street businesses, ceased trading and consequently, unemployment rates rose to the highest levels since the 1980s. After the initial ‘bailout’ of the banking sector, political attention turned to the growing public deficit and the spectre of public sector austerity came to dominate the policy agenda. This agenda swiftly moved from how best to regulate the financial services industry to the question of the ‘welfare bill’ and the growing problem of ‘worklessness’. From this point, particularly as the Universal Credit Scheme passed through parliament and came to be implemented in various phases, much was said in political and policy debates about the lives of the ‘poor’ and many ‘common sense’ assumptions informed these discussions. However as is often the case, omitted from these discussions were the voices of those people living of low income. To redress this imbalance, the report aims to document the reality of life on a low income during this period, by affording primacy to the ‘voices’ of those living in poverty
Exploring the extended density-dependent Skyrme effective forces for normal and isospin-rich nuclei to neutron stars
We parameterize the recently proposed generalized Skyrme effective force
(GSEF) containing extended density dependence. The parameters of the GSEF are
determined by the fit to several properties of the normal and isospin-rich
nuclei. We also include in our fit a realistic equation of state for the pure
neutron matter up to high densities so that the resulting Skyrme parameters can
be suitably used to model the neutron star with the "canonical" mass (). For the appropriate comparison we generate a parameter set for the
standard Skyrme effective force (SSEF) using exactly the same set of the data
as employed to determine the parameters of the GSEF. We find that the GSEF
yields larger values for the neutron skin thickness which are closer to the
recent predictions based on the isospin diffusion data. The Skyrme parameters
so obtained are employed to compute the strength function for the isoscalar
giant monopole, dipole and quadrupole resonances. It is found that in the case
of GSEF, due to the the larger value of the nucleon effective mass the values
of centroid energies for the isoscalar giant resonances are in better agreement
with the corresponding experimental data in comparison to those obtained using
the SSEF. We also present results for some of the key properties associated
with the neutron star of "canonical" mass and for the one with the maximum
mass.Comment: 45pages, 16 figure
Degree of Complementarity Determines the Nonlocality in Quantum Mechanics
Complementarity principle is one of the central concepts in quantum mechanics
which restricts joint measurement for certain observables. Of course, later
development shows that joint measurement could be possible for such observables
with the introduction of a certain degree of unsharpness or fuzziness in the
measurement. In this paper, we show that the optimal degree of unsharpness,
which guarantees the joint measurement of all possible pairs of dichotomic
observables, determines the degree of nonlocality in quantum mechanics as well
as in more general no-signaling theories.Comment: Close to published versio
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