160 research outputs found
Quantum coherence of discrete kink solitons in ion traps
We propose to realize quantized discrete kinks with cold trapped ions. We
show that long-lived solitonlike configurations are manifested as deformations
of the zigzag structure in the linear Paul trap, and are topologically
protected in a circular trap with an odd number of ions. We study the
quantum-mechanical time evolution of a high-frequency, gap separated internal
mode of a static kink and find long coherence times when the system is cooled
to the Doppler limit. The spectral properties of the internal modes make them
ideally suited for manipulation using current technology. This suggests that
ion traps can be used to test quantum-mechanical effects with solitons and
explore ideas for the utilization of the solitonic internal-modes as carriers
of quantum information.Comment: 5 pages, 4 figures ; minor correction
Is Communication Complexity Physical?
Recently, Brassard et. al. conjectured that the fact that the maximal
possible correlations between two non-local parties are the quantum-mechanical
ones is linked to a reasonable restriction on communication complexity. We
provide further support for the conjecture in the multipartite case. We show
that any multipartite communication complexity problem could be reduced to
triviality, had Nature been more non-local than quantum-mechanics by a quite
small gap for any number of parties. Intriguingly, the multipartite
nonlocal-box that we use to show the result corresponds to the generalized Bell
inequality that manifests maximal violation in respect to a local
hidden-variable theory
Is there a link between dizziness and vision? A systematic review
YesPurpose: The aim of this study was to systematically review the literature to investigate
the link (if any) between vision and dizziness.
Methods: Medline, CINAHL, AMED, Web of Science and The Cochrane Library
were searched with keywords chosen to find articles which investigated the causes
of dizziness and considered vision as a possible trigger. Citation chaining of all
included papers was performed in addition to the hand searching of all reference
lists. Unpublished literature was identified using www.opengrey.eu. The review
considered studies involving adults which link, measure or attempt to improve
any aspect of vision in relation to dizziness.
Results: Nine thousand six hundred and eighty one possible references were
found, and the abstracts were screened independently by two reviewers to determine
if they should be included in the study. Thirteen papers were found which
investigated whether dizziness was linked to an assessment of vision. Visual
impairment measures were crude and typically self-report, or Snellen visual acuity
with little or no measurement details. Five studies found an independent link
between dizziness and vision, five found a weak association (typically finding a
link when univariate analyses were used, but not when multivariate analyses were
used), and three found no association. Studies finding a strong link were usually
cross-sectional with a large study population whereas those finding a weak association
had relatively small numbers of participants. Studies which did not find an
association used a broad definition of dizziness that included the term light-headedness,
an unreliable Rosenbaum near visual acuity chart or an unusual categorisation
of visual acuity.
Conclusions: This review suggests that dizziness (although likely not ‘light-headedness’)
is linked with poor vision although further studies using more appropriate
measures of vision are recommended.Deborah Armstrong was funded by a College of Optometrists Research Scholarship and Emily Charlesworth by a College of Optometrists summer studentship
Why Full Open Access Matters
This perspective explains the mechanics of copyright and scholarly publishing and warns authors who support open-access publishing about a new pseudo open-access publishing model in which authors pay but publishers still retain commercial reuse rights
The information sources and journals consulted or read by UK paediatricians to inform their clinical practice and those which they consider important: a questionnaire survey
Background: Implementation of health research findings is important for medicine to be
evidence-based. Previous studies have found variation in the information sources thought to be of greatest importance to clinicians but publication in peer-reviewed journals is the traditional route for dissemination of research findings. There is debate about whether the impact made on clinicians should be considered as part of the evaluation of research outputs. We aimed to determine first which information sources are generally most consulted by paediatricians to inform their clinical practice, and which sources they considered most important, and second, how many and which peer-reviewed journals they read.
Methods: We enquired, by questionnaire survey, about the information sources and academic
journals that UK medical paediatric specialists generally consulted, attended or read and
considered important to their clinical practice.
Results: The same three information sources – professional meetings & conferences, peerreviewed
journals and medical colleagues – were, overall, the most consulted or attended and ranked the most important. No one information source was found to be of greatest importance to all groups of paediatricians. Journals were widely read by all groups, but the proportion ranking them first in importance as an information source ranged from 10% to 46%. The number of journals read varied between the groups, but Archives of Disease in Childhood and BMJ were the most read
journals in all groups. Six out of the seven journals previously identified as containing best paediatric evidence are the most widely read overall by UK paediatricians, however, only the two most prominent are widely read by those based in the community.
Conclusion: No one information source is dominant, therefore a variety of approaches to
Continuing Professional Development and the dissemination of research findings to paediatricians should be used. Journals are an important information source. A small number of key ones can be identified and such analysis could provide valuable additional input into the evaluation of clinical research outputs
Holographic View on Quantum Correlations and Mutual Information between Disjoint Blocks of a Quantum Critical System
In (d+1) dimensional Multiscale Entanglement Renormalization Ansatz (MERA)
networks, tensors are connected so as to reproduce the discrete, (d + 2)
holographic geometry of Anti de Sitter space (AdSd+2) with the original system
lying at the boundary. We analyze the MERA renormalization flow that arises
when computing the quantum correlations between two disjoint blocks of a
quantum critical system, to show that the structure of the causal cones
characteristic of MERA, requires a transition between two different regimes
attainable by changing the ratio between the size and the separation of the two
disjoint blocks. We argue that this transition in the MERA causal developments
of the blocks may be easily accounted by an AdSd+2 black hole geometry when the
mutual information is computed using the Ryu-Takayanagi formula. As an explicit
example, we use a BTZ AdS3 black hole to compute the MI and the quantum
correlations between two disjoint intervals of a one dimensional boundary
critical system. Our results for this low dimensional system not only show the
existence of a phase transition emerging when the conformal four point ratio
reaches a critical value but also provide an intuitive entropic argument
accounting for the source of this instability. We discuss the robustness of
this transition when finite temperature and finite size effects are taken into
account.Comment: 21 pages, 5 figures. Abstract and Figure 1 has been modified. Minor
modifications in Section 1 and Section
“Excellence R Us”: university research and the fetishisation of excellence
The rhetoric of “excellence” is pervasive across the academy. It is used to refer to research outputs as well as researchers, theory and education, individuals and organisations, from art history to zoology. But does “excellence” actually mean anything? Does this pervasive narrative of “excellence” do any good? Drawing on a range of sources we interrogate “excellence” as a concept and find that it has no intrinsic meaning in academia. Rather it functions as a linguistic interchange mechanism. To investigate whether this linguistic function is useful we examine how the rhetoric of excellence combines with narratives of scarcity and competition to show that the hypercompetition that arises from the performance of “excellence” is completely at odds with the qualities of good research. We trace the roots of issues in reproducibility, fraud, and homophily to this rhetoric. But we also show that this rhetoric is an internal, and not primarily an external, imposition. We conclude by proposing an alternative rhetoric based on soundness and capacity-building. In the final analysis, it turns out that that “excellence” is not excellent. Used in its current unqualified form it is a pernicious and dangerous rhetoric that undermines the very foundations of good research and scholarship
Perceptions of, and reactions to, environmental heat: a brief note on issues of concern in relation to occupational health
Average temperatures around the world are already increasing, and climate change projections suggest that global mean temperatures will continue to rise. As the effects, and projected effects, of climate change are becoming clearer, it is more apparent that the health effects of heat exposure will need further investigation. The risks associated with heat exposure are especially relevant to understandings of occupational health for people involved in labouring or agricultural work in low-income countries. This review is a partial look at the ways in which issues surrounding heat exposure and occupational health have been treated in some of the available literature. This literature focuses on military-related medical understandings of heat exposure as well as heat exposure in working environments. The ways that these issues have been treated throughout the literature reflect the ways in which technologies of observation are intertwined with social attitudes. The effects of heat on the health of working people, as well as identification of risk groups, will require further research in order to promote prophylactic measures as well as to add to understandings of the actual and potential consequences of climatic change
Multiple publications: The main reason for the retraction of papers in computer science
This paper intends to review the reasons for the retraction over the last decade. The paper particularly aims at reviewing these reasons with reference to computer science field to assist authors in comprehending the style of writing. To do that, a total of thirty-six retracted papers found on the Web of Science within Jan 2007 through July 2017 are explored. Given the retraction notices which are based on ten common reasons, this paper classifies the two main categories, namely random and nonrandom retraction. Retraction due to the duplication of publications scored the highest proportion of all other reasons reviewed
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