710 research outputs found
Enhanced nasopharyngeal infection and shedding associated with an epidemic lineage of emm3 group A Streptococcus
Background:
A group A Streptococcus (GAS) lineage of genotype emm3, sequence type 15 (ST15) was
associated with a six month upsurge in invasive GAS disease in the UK. The epidemic lineage
(Lineage C) had lost two typical emm3 prophages, Φ315.1 and Φ315.2 associated with the
superantigen ssa, but gained a different prophage (ΦUK-M3.1) associated with a different
superantigen, speC and a DNAse spd1.
Methods and Results:
The presence of speC and spd1 in Lineage C ST15 strains enhanced both in vitro mitogenic
and DNAse activities over non-Lineage C ST15 strains. Invasive disease models in Galleria
mellonella and SPEC-sensitive transgenic mice, revealed no difference in overall invasiveness
of Lineage C ST15 strains compared to non-Lineage C ST15 strains, consistent with clinical
and epidemiological analysis. Lineage C strains did however markedly prolong murine nasal
infection with enhanced nasal and airborne shedding compared to non-Lineage C strains.
Deletion of speC or spd1 in two Lineage C strains identified a possible role for spd1 in airborne
shedding from the murine nasopharynx.
Conclusions:
Nasopharyngeal infection and shedding of Lineage C strains was enhanced compared to nonLineage
C strains and this was, in part, mediated by the gain of the DNase spd1 through prophage acquisition
Towards the Formalization of Fractional Calculus in Higher-Order Logic
Fractional calculus is a generalization of classical theories of integration
and differentiation to arbitrary order (i.e., real or complex numbers). In the
last two decades, this new mathematical modeling approach has been widely used
to analyze a wide class of physical systems in various fields of science and
engineering. In this paper, we describe an ongoing project which aims at
formalizing the basic theories of fractional calculus in the HOL Light theorem
prover. Mainly, we present the motivation and application of such formalization
efforts, a roadmap to achieve our goals, current status of the project and
future milestones.Comment: 9 page
Quantizing higher-spin gravity in free-field variables
We study the formulation of massless higher-spin gravity on AdS in a
gauge in which the fundamental variables satisfy free field Poisson brackets.
This gauge choice leaves a small portion of the gauge freedom unfixed, which
should be further quotiented out. We show that doing so leads to a bulk version
of the Coulomb gas formalism for CFT's: the generators of the residual
gauge symmetries are the classical limits of screening charges, while the
gauge-invariant observables are classical charges. Quantization in these
variables can be carried out using standard techniques and makes manifest a
remnant of the triality symmetry of . This symmetry can be
used to argue that the theory should be supplemented with additional matter
content which is precisely that of the Prokushkin-Vasiliev theory. As a further
application, we use our formulation to quantize a class of conical surplus
solutions and confirm the conjecture that these are dual to specific degenerate
primaries, to all orders in the large central charge expansion.Comment: 31 pages + appendices. V2: typos corrected, reference adde
The GRA Beam-Splitter Experiments and Particle-Wave Duality of Light
Grangier, Roger and Aspect (GRA) performed a beam-splitter experiment to
demonstrate the particle behaviour of light and a Mach-Zehnder interferometer
experiment to demonstrate the wave behaviour of light. The distinguishing
feature of these experiments is the use of a gating system to produce near
ideal single photon states. With the demonstration of both wave and particle
behaviour (in two mutually exclusive experiments) they claim to have
demonstrated the dual particle-wave behaviour of light and hence to have
confirmed Bohr's principle of complementarity. The demonstration of the wave
behaviour of light is not in dispute. But we want to demonstrate, contrary to
the claims of GRA, that their beam-splitter experiment does not conclusively
confirm the particle behaviour of light, and hence does not confirm
particle-wave duality, nor, more generally, does it confirm complementarity.
Our demonstration consists of providing a detailed model based on the Causal
Interpretation of Quantum Fields (CIEM), which does not involve the particle
concept, of GRA's which-path experiment. We will also give a brief outline of a
CIEM model for the second, interference, GRA experiment.Comment: 24 pages, 4 figure
Rotating Higher Spin Partition Functions and Extended BMS Symmetries
We evaluate one-loop partition functions of higher-spin fields in thermal
flat space with angular potentials; this computation is performed in arbitrary
space-time dimension, and the result is a simple combination of Poincar\'e
characters. We then focus on dimension three, showing that suitable products of
one-loop partition functions coincide with vacuum characters of higher-spin
asymptotic symmetry algebras at null infinity. These are extensions of the
bms_3 algebra that emerges in pure gravity, and we propose a way to build their
unitary representations and to compute the associated characters. We also
extend our investigations to supergravity and to a class of gauge theories
involving higher-spin fermionic fields.Comment: 58 pages; clarifications and references added; version to be
published in JHE
Assessment of fluorescent amplified fragment length polymorphism analysis for epidemiological genotyping of Legionella pneumophila serogroup 1
n/
Group B streptococcal carriage, serotype distribution and antibiotic susceptibilities in pregnant women at the time of delivery in a refugee population on the Thai-Myanmar border
<p>Abstract</p> <p>Background</p> <p>Group B Streptococcus (GBS) is the leading cause of neonatal sepsis in the developed world. Little is known about its epidemiology in the developing world, where the majority of deaths from neonatal infections occur. Maternal carriage of GBS is a prerequisite for the development of early onset GBS neonatal sepsis but there is a paucity of carriage data published from the developing world, in particular South East Asia.</p> <p>Methods</p> <p>We undertook a cross sectional study over a 13 month period in a remote South East Asian setting on the Thai-Myanmar border. During labour, 549 mothers had a combined vaginal rectal swab taken for GBS culture. All swabs underwent both conventional culture as well as PCR for GBS detection. Cultured GBS isolates were serotyped by latex agglutination, those that were negative or had a weak positive reaction and those that were PCR positive but culture negative were additionally tested using multiplex PCR based on the detection of GBS capsular polysaccharide genes.</p> <p>Results</p> <p>The GBS carriage rate was 12.0% (95% CI: 9.4-15.0), with 8.6% positive by both culture and PCR and an additional 3.5% positive by PCR alone. Serotypes, Ia, Ib, II, III, IV, V, VI and VII were identified, with II the predominant serotype. All GBS isolates were susceptible to penicillin, ceftriaxone and vancomycin and 43/47 (91.5%) were susceptible to erythromycin and clindamycin.</p> <p>Conclusions</p> <p>GBS carriage is not uncommon in pregnant women living on the Thai-Myanmar border with a large range of serotypes represented.</p
Testing foundations of quantum mechanics with photons
The foundational ideas of quantum mechanics continue to give rise to
counterintuitive theories and physical effects that are in conflict with a
classical description of Nature. Experiments with light at the single photon
level have historically been at the forefront of tests of fundamental quantum
theory and new developments in photonics engineering continue to enable new
experiments. Here we review recent photonic experiments to test two
foundational themes in quantum mechanics: wave-particle duality, central to
recent complementarity and delayed-choice experiments; and Bell nonlocality
where recent theoretical and technological advances have allowed all
controversial loopholes to be separately addressed in different photonics
experiments.Comment: 10 pages, 5 figures, published as a Nature Physics Insight review
articl
On Effective Potential in Tortoise Coordinate
In this paper, we study the field dynamics in Tortoise coordinate where the
equation of motion of a scalar can be written as Schrodinger-like form. We
obtain a general form for effective potential by finding the Schrodinger
equation for scalar and spinor fields and study its global behavior in some
black hole backgrounds in three dimension such as BTZ black holes, new type
black holes and black holes with no horizon.
Especially, we study the asymptotic behavior of potential at infinity,
horizons and origin and find that its asymptotic in BTZ and new type solution
is completely different from that of vanishing horizon solution. In fact,
potential for vanishing horizon goes to a fixed quantity at infinity, while in
BTZ and new type black hole we have an infinite barrier.Comment: 18 pages, 9 figure
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