783 research outputs found
Holography in 4D (Super) Higher Spin Theories and a Test via Cubic Scalar Couplings
The correspondences proposed previously between higher spin gauge theories
and free singleton field theories were recently extended into a more complete
picture by Klebanov and Polyakov in the case of the minimal bosonic theory in
D=4 to include the strongly coupled fixed point of the 3d O(N) vector model.
Here we propose an N=1 supersymmetric version of this picture. We also
elaborate on the role of parity in constraining the bulk interactions, and in
distinguishing two minimal bosonic models obtained as two different consistent
truncations of the minimal N=1 model that retain the scalar or the
pseudo-scalar field. We refer to these models as the Type A and Type B models,
respectively, and conjecture that the latter is holographically dual to the 3d
Gross-Neveu model. In the case of the Type A model, we show the vanishing of
the three-scalar amplitude with regular boundary conditions. This agrees with
the O(N) vector model computation of Petkou, thereby providing a non-trivial
test of the Klebanov-Polyakov conjecture.Comment: 30p
An Exact Solution of 4D Higher-Spin Gauge Theory
We give a one-parameter family of exact solutions to four-dimensional
higher-spin gauge theory invariant under a deformed higher-spin extension of
SO(3,1) and parameterized by a zero-form invariant. All higher-spin gauge
fields vanish, while the metric interpolates between two asymptotically AdS4
regions via a dS3-foliated domainwall and two H3-foliated Robertson-Walker
spacetimes -- one in the future and one in the past -- with the scalar field
playing the role of foliation parameter. All Weyl tensors vanish, including
that of spin two. We furthermore discuss methods for constructing solutions,
including deformation of solutions to pure AdS gravity, the gauge-function
approach, the perturbative treatment of (pseudo-)singular initial data
describing isometric or otherwise projected solutions, and zero-form
invariants.Comment: 47 pages. v3: global properties of the solution clarified, minor
corrections made, discussion and refs revise
Scalar Field Corrections to AdS_4 Gravity from Higher Spin Gauge Theory
We compute the complete contribution to the stress-energy tensor in the
minimal bosonic higher spin theory in D=4 that is quadratic in the scalar
field. We find arbitrarily high derivative terms, and that the total sign of
the stress-energy tensor depends on the parity of the scalar field.Comment: 15 pages + appendix (30 pages
Draft genome sequence of extended-spectrum-β-lactamase-producing Escherichia coli strain CCUG 62462, isolated from a urine sample
The draft genome sequence has been determined for an extended-spectrum-β-lactamase (ESBL)-producing (blaCTX-M-15) Escherichia coli strain (CCUG 62462), composed of 119 contigs and a total size of 5.27 Mb. This E. coli is serotype O25b and sequence type 131, a pandemic clonal group, causing worldwide antimicrobial-resistant infections
Dianion diagnostics in DESIREE: High-sensitivity detection of from a sputter ion source
A sputter ion source with a solid graphite target has been used to produce
dianions with a focus on carbon cluster dianions, , with
. Singly and doubly charged anions from the source were accelerated
together to kinetic energies of 10 keV per atomic unit of charge and injected
into one of the cryogenic (13 K) ion-beam storage rings of the Double
ElectroStatic Ion Ring Experiment facility at Stockholm University. Spontaneous
decay of internally hot dianions injected into the ring
yielded anions with kinetic energies of 20 keV, which were
counted with a microchannel plate detector. Mass spectra produced by scanning
the magnetic field of a analyzing magnet on the ion injection line
reflect the production of internally hot
dianions with lifetimes in the range of tens of microseconds to milliseconds.
In spite of the high sensitivity of this method, no conclusive evidence of
was found while there was a clear
signal with the expect isotopic distribution. An upper limit is deduced for a
signal that is two orders-of-magnitue smaller than that for
. In addition, and
dianions were detected.Comment: 6 pages, 6 figure
Photon capture cones and embedding diagrams of the Ernst spacetime
The differences between the character of the Schwarzschild and Ernst
spacetimes are illustrated by comparing the photon capture cones, and the
embedding diagrams of the sections of the equatorial planes
of both the ordinary and optical reference geometry of these spacetimes. The
non-flat asymptotic character of the Ernst spacetime reflects itself in two
manifest facts: the escape photon cones correspond to purely outward radial
direction, and the embedding diagrams of both the ordinary and optical geometry
shrink to zero radius asymptotically. Using the properties of the embedding
diagrams, regions of these spacetimes which could have similar character are
estimated, and it is argued that they can exist for the Ernst spacetimes with a
sufficiently low strength of the magnetic field.Comment: 12 pages, 7 figure
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Investigating the impact of poverty on colonization and infection with drug-resistant organisms in humans: a systematic review
Background
Poverty increases the risk of contracting infectious diseases and therefore exposure to antibiotics. Yet there is lacking evidence on the relationship between income and non-income dimensions of poverty and antimicrobial resistance. Investigating such relationship would strengthen antimicrobial stewardship interventions.
Methods
A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Ovid, MEDLINE, EMBASE, Scopus, CINAHL, PsychINFO, EBSCO, HMIC, and Web of Science databases were searched in October 2016. Prospective and retrospective studies reporting on income or non-income dimensions of poverty and their influence on colonisation or infection with antimicrobial-resistant organisms were retrieved. Study quality was assessed with the Integrated quality criteria for review of multiple study designs (ICROMS) tool.
Results
Nineteen articles were reviewed. Crowding and homelessness were associated with antimicrobial resistance in community and hospital patients. In high-income countries, low income was associated with Streptococcus pneumoniae and Acinetobacter baumannii resistance and a seven-fold higher infection rate. In low-income countries the findings on this relation were contradictory. Lack of education was linked to resistant S. pneumoniae and Escherichia coli. Two papers explored the relation between water and sanitation and antimicrobial resistance in low-income settings.
Conclusions
Despite methodological limitations, the results suggest that addressing social determinants of poverty worldwide remains a crucial yet neglected step towards preventing antimicrobial resistance
On the covariant quantization of tensionless bosonic strings in AdS spacetime
The covariant quantization of the tensionless free bosonic (open and closed)
strings in AdS spaces is obtained. This is done by representing the AdS space
as an hyperboloid in a flat auxiliary space and by studying the resulting
string constrained hamiltonian system in the tensionless limit. It turns out
that the constraint algebra simplifies in the tensionless case in such a way
that the closed BRST quantization can be formulated and the theory admits then
an explicit covariant quantization scheme. This holds for any value of the
dimension of the AdS space.Comment: 1+16 pages; v4 two clarifications adde
Invariant Differential Operators and Characters of the AdS_4 Algebra
The aim of this paper is to apply systematically to AdS_4 some modern tools
in the representation theory of Lie algebras which are easily generalised to
the supersymmetric and quantum group settings and necessary for applications to
string theory and integrable models. Here we introduce the necessary
representations of the AdS_4 algebra and group. We give explicitly all singular
(null) vectors of the reducible AdS_4 Verma modules. These are used to obtain
the AdS_4 invariant differential operators. Using this we display a new
structure - a diagram involving four partially equivalent reducible
representations one of which contains all finite-dimensional irreps of the
AdS_4 algebra. We study in more detail the cases involving UIRs, in particular,
the Di and the Rac singletons, and the massless UIRs. In the massless case we
discover the structure of sets of 2s_0-1 conserved currents for each spin s_0
UIR, s_0=1,3/2,... All massless cases are contained in a one-parameter
subfamily of the quartet diagrams mentioned above, the parameter being the spin
s_0. Further we give the classification of the so(5,C) irreps presented in a
diagramatic way which makes easy the derivation of all character formulae. The
paper concludes with a speculation on the possible applications of the
character formulae to integrable models.Comment: 30 pages, 4 figures, TEX-harvmac with input files: amssym.def,
amssym.tex, epsf.tex; version 2 1 reference added; v3: minor corrections;
v.4: minor corrections, v.5: minor corrections to conform with version in J.
Phys. A: Math. Gen; v.6.: small correction and addition in subsections 4.1 &
4.
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