62,671 research outputs found
New Slant on the EPR-Bell Experiment
The best case for thinking that quantum mechanics is nonlocal rests on Bell's
Theorem, and later results of the same kind. However, the correlations
characteristic of EPR-Bell (EPRB) experiments also arise in familiar cases
elsewhere in QM, where the two measurements involved are timelike rather than
spacelike separated; and in which the correlations are usually assumed to have
a local causal explanation, requiring no action-at-a-distance. It is
interesting to ask how this is possible, in the light of Bell's Theorem. We
investigate this question, and present two options. Either (i) the new cases
are nonlocal, too, in which case action-at-a-distance is more widespread in QM
than has previously been appreciated (and does not depend on entanglement, as
usually construed); or (ii) the means of avoiding action-at-a-distance in the
new cases extends in a natural way to EPRB, removing action-at-a-distance in
these cases, too. There is a third option, viz., that the new cases are
strongly disanalogous to EPRB. But this option requires an argument, so far
missing, that the physical world breaks the symmetries which otherwise support
the analogy. In the absence of such an argument, the orthodox combination of
views -- action-at-a-distance in EPRB, but local causality in its timelike
analogue -- is less well established than it is usually assumed to be.Comment: 26 pages, 7 figures; extensively revised for resubmissio
Is the Water Sector Lagging behind Education and Health on Aid Effectiveness? Lessons from Bangladesh, Ethiopia and Uganda
A study in three countries (Bangladesh, Ethiopia and Uganda) assessed progress against the Paris Principles for Aid Effectiveness (AE) in three sectors – water, health and education – to test the assumption that the water sector is lagging behind. The findings show that it is too simplistic to say that the water sector is lagging, although this may well be the case in some countries. The study found that wider governance issues are more important for AE than having in place sector-specific mechanics such as Sector-Wide Approaches alone. National political leadership and governance are central drivers of sector AE, while national financial and procurement systems and the behaviour of actors who have not signed up to the Paris Principles – at both national and global levels – have implications for progress that cut across sectors. Sectors and sub-sectors do nonetheless have distinct features that must be considered in attempting to improve sector-level AE. In light of these findings, using political economy approaches to better understand and address governance and strengthening sector-level monitoring is recommended as part of efforts to improve AE and development results in the water sector
Conserved mass models with stickiness and chipping
We study a chipping model in one dimensional periodic lattice with continuous
mass, where a fixed fraction of the mass is chipped off from a site and
distributed randomly among the departure site and its neighbours; the remaining
mass sticks to the site. In the asymmetric version, the chipped off mass is
distributed among the site and the right neighbour, whereas in the symmetric
version the redistribution occurs among the two neighbours. The steady state
mass distribution of the model is obtained using a perturbation method for both
parallel and random sequential updates. In most cases, this perturbation theory
provides a steady state distribution with reasonable accuracy.Comment: 17 pages, 4 eps figure
Phase Transition in the ABC Model
Recent studies have shown that one-dimensional driven systems can exhibit
phase separation even if the dynamics is governed by local rules. The ABC
model, which comprises three particle species that diffuse asymmetrically
around a ring, shows anomalous coarsening into a phase separated steady state.
In the limiting case in which the dynamics is symmetric and the parameter
describing the asymmetry tends to one, no phase separation occurs and the
steady state of the system is disordered. In the present work we consider the
weak asymmetry regime where is the system size and
study how the disordered state is approached. In the case of equal densities,
we find that the system exhibits a second order phase transition at some
nonzero .
The value of and the optimal profiles can be
obtained by writing the exact large deviation functional. For nonequal
densities, we write down mean field equations and analyze some of their
predictions.Comment: 18 pages, 3 figure
Numerical Evidence for Divergent Burnett Coefficients
In previous papers [Phys. Rev. A {\bf 41}, 4501 (1990), Phys. Rev. E {\bf
18}, 3178 (1993)], simple equilibrium expressions were obtained for nonlinear
Burnett coefficients. A preliminary calculation of a 32 particle Lennard-Jones
fluid was presented in the previous paper. Now, sufficient resources have
become available to address the question of whether nonlinear Burnett
coefficients are finite for soft spheres. The hard sphere case is known to have
infinite nonlinear Burnett coefficients (ie a nonanalytic constitutive
relation) from mode coupling theory. This paper reports a molecular dynamics
caclulation of the third order nonlinear Burnett coefficient of a Lennard-Jones
fluid undergoing colour flow, which indicates that this term is diverges in the
thermodynamic limit.Comment: 12 pages, 9 figure
Identifying optimal feature transforms for classification and prediction in biological systems: recovering receptive field vectors from sparse recordings
With biological systems it is often hard to adequately sample the entire input space. With sensory neural systems this can be a particularly acute problem, with very high dimensional natural inputs and typically sparse spiking outputs. Here we present an information theory based approach to analyse spiking data of an early sensory pathway, demonstrated on retinal ganglion cells (RGC) responding to natural visual scene stimuli (Katz et al., 2016). We used a non-parametric technique based on the concept of mutual information (MI), in particular, Quadratic Mutual Information (QMI). The QMI allowed us to very efficiently search the high dimensional space formed by the visual input for a much smaller dimensional subspace of Receptive Field Vectors (RFV). RFVs give the most information about the response of the cell to natural stimuli. This approach allows us to identify the RFVs far more efficiently using limited data as we can search the complete stimulus space for multiple vectors simultaneously. The RFVs were also used to predict the RGCs’ responses to any natural stimuli. Another suitable area of application of this algorithm is in diagnostic inference. Currently we are adapting the method to be used for identifying the cancer markers in the volatile organic compounds present in exhaled breath. Once the maximally informative features are established they can be used for diagnostic predictions on new breath samples. Preliminary results of the breathomics analysis will be discussed at the conference. There are several other potential applications such as multiclass categorisation for bacterial strains using ISFET arrays for DNA sequencing. This algorithm can be part of a rapid point-of-care device for identifying the specific infectious agents and recommending appropriate antibiotics. Here we will focus on presenting the algorithm using the example of RFVs of RGCs
The perception of familiar and unfamiliar accents by bilingual and monolingual children
In large urban cities, children typically grow-up in a
diverse multicultural environment. Depending on
their local language environment, children are often
exposed to regional as well as foreign-accents. This
study investigated whether children’s accent
processing is affected by the variability in their
ambient language environment.
English monolingual and Sylheti-English
bilingual children were assessed on their ability to
identify sentences in three accent conditions:
London-English (familiar to all), Sylheti-accented
English (only familiar to the bilinguals), Spanishaccented English (unfamiliar to all). All children were
most accurate in the London-English accent
condition, however the groups differed with their
dominant familiar accent: the monolinguals were
more accurate at recalling the London-English
sentences than the bilinguals, and the bilinguals were
more accurate in the Sylheti-accented condition than
the monolinguals.
The results suggest that variation in linguistic
experience in early life, give rise to differences in the
processing of familiar and unfamiliar accented
speech
Condensation Transitions in Two Species Zero-Range Process
We study condensation transitions in the steady state of a zero-range process
with two species of particles. The steady state is exactly soluble -- it is
given by a factorised form provided the dynamics satisfy certain constraints --
and we exploit this to derive the phase diagram for a quite general choice of
dynamics. This phase diagram contains a variety of new mechanisms of condensate
formation, and a novel phase in which the condensate of one of the particle
species is sustained by a `weak' condensate of particles of the other species.
We also demonstrate how a single particle of one of the species (which plays
the role of a defect particle) can induce Bose-Einstein condensation above a
critical density of particles of the other species.Comment: 17 pages, 4 Postscript figure
To what extent does severity of loneliness vary among different mental health diagnostic groups: A cross-sectional study.
Loneliness is a common and debilitating problem in individuals with mental health disorders. However, our knowledge on severity of loneliness in different mental health diagnostic groups and factors associated with loneliness is poor, thus limiting the ability to target and improve loneliness interventions. The current study investigated the association between diagnoses and loneliness and explored whether psychological and social factors were related to loneliness. This study employed a cross-sectional design using data from a completed study which developed a measure of social inclusion. It included 192 participants from secondary, specialist mental health services with a primary diagnosis of psychotic disorders (n = 106), common mental disorders (n = 49), or personality disorders (n = 37). The study explored differences in loneliness between these broad diagnostic groups, and the relationship to loneliness of: affective symptoms, social isolation, perceived discrimination, and internalized stigma. The study adhered to the STROBE checklist for observational research. People with common mental disorders (MD = 3.94, CI = 2.15 to 5.72, P < 0.001) and people with personality disorders (MD = 4.96, CI = 2.88 to 7.05, P < 0.001) reported higher levels of loneliness compared to people with psychosis. These differences remained significant after adjustment for all psychological and social variables. Perceived discrimination and internalized stigma were also independently associated with loneliness and substantially contributed to a final explanatory model. The severity of loneliness varies between different mental health diagnostic groups. Both people with common mental disorders and personality disorders reported higher levels of loneliness than people with psychosis. Addressing perceived mental health discrimination and stigma may help to reduce loneliness
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