66 research outputs found
A unique measles B3 cluster in the United Kingdom and the Netherlands linked to air travel and transit at a large international airport, February to April 2014
Rita de Sousa (Bolseira EUPHEM) - Investigadora do Departamento de Doenças Infeciosas do Instituto Ricardo JorgeThis report describes a joint measles outbreak investigation between public health officials in the United Kingdom (UK) and the Netherlands following detection of a measles cluster with a unique measles virus strain. From 1 February to 30 April 2014, 33 measles cases with a unique measles virus strain of genotype B3 were detected in the UK and the Netherlands, of which nine secondary cases were epidemiologically linked to an infectious measles case travelling from the Philippines. Through a combination of epidemiological investigation and sequence analysis, we found that measles transmission occurred in flight, airport and household settings. The secondary measles cases included airport workers, passengers in transit at the same airport or travelling on the same flight as the infectious case and also household contacts. This investigation highlighted the particular importance of measles genotyping in identifying transmission networks and the need to improve vaccination, public health follow-up and management of travellers and airport staff exposed to measles.info:eu-repo/semantics/publishedVersio
Light scattering observations of spin reversal excitations in the fractional quantum Hall regime
Resonant inelastic light scattering experiments access the low lying
excitations of electron liquids in the fractional quantum Hall regime in the
range . Modes associated with changes in the charge and
spin degrees of freedom are measured. Spectra of spin reversed excitations at
filling factor and at identify a structure
of lowest spin-split Landau levels of composite fermions that is similar to
that of electrons. Observations of spin wave excitations enable determinations
of energies required to reverse spin. The spin reversal energies obtained from
the spectra illustrate the significant residual interactions of composite
fermions. At energies of spin reversal modes are larger but
relatively close to spin conserving excitations that are linked to activated
transport. Predictions of composite fermion theory are in good quantitative
agreement with experimental results.Comment: Submitted to special issue of Solid State Com
Spin excitations in the Fractional Quantum Hall regime at
We report inelastic light scattering experiments in the fractional quantum
Hall regime at filling factors . A spin mode is observed below
the Zeeman energy. The filling factor dependence of the mode energy is
consistent with its assignment to spin flip excitations of composite fermions
with four attached flux quanta (=4). Our findings reveal a composite
fermion Landau level structure in the =4 sequence.Comment: 7 pages, 4 figures, EP2DS-16 conference, to appear in Physica
Resonant Enhancement of Inelastic Light Scattering in the Fractional Quantum Hall Regime at
Strong resonant enhancements of inelastic light scattering from the long
wavelength inter-Landau level magnetoplasmon and the intra-Landau level spin
wave excitations are seen for the fractional quantum Hall state at .
The energies of the sharp peaks (FWHM ) in the profiles of
resonant enhancement of inelastic light scattering intensities coincide with
the energies of photoluminescence bands assigned to negatively charged exciton
recombination. To interpret the observed enhancement profiles, we propose
three-step light scattering mechanisms in which the intermediate resonant
transitions are to states with charged excitonic excitations.Comment: 5 pages, 5 figure
Edge reconstruction in the fractional quantum Hall regime
The interplay of electron-electron interaction and confining potential can
lead to the reconstruction of fractional quantum Hall edges. We have performed
exact diagonalization studies on microscopic models of fractional quantum Hall
liquids, in finite size systems with disk geometry, and found numerical
evidence of edge reconstruction under rather general conditions. In the present
work we have taken into account effects like layer thickness and Landau level
mixing, which are found to be of quantitative importance in edge physics. Due
to edge reconstruction, additional nonchiral edge modes arise for both
incompressible and compressible states. These additional modes couple to
electromagnetic fields and thus can be detected in microwave conductivity
measurements. They are also expected to affect the exponent of electron Green's
function, which has been measured in tunneling experiments. We have studied in
this work the electric dipole spectral function that is directly related to the
microwave conductivity measurement. Our results are consistent with the
enhanced microwave conductivity observed in experiments performed on samples
with an array of antidots at low temperatures, and its suppression at higher
temperatures. We also discuss the effects of the edge reconstruction on the
single electron spectral function at the edge.Comment: 19 pages, 12 figure
A Relation Between Approaches to Integrability in Superconformal Yang-Mills Theory
We make contact between the infinite-dimensional non-local symmetry of the
typeIIB superstring on AdS5xS5 worldsheet theory and a non-abelian
infinite-dimensional symmetry algebra for the weakly coupled superconformal
gauge theory. We explain why the planar limit of the one-loop dilatation
operator is the Hamiltonian of a spin chain, and show that it commutes with the
g*2 N = 0 limit of the non-abelian charges.Comment: 19 pages, harvma
Superconformal operators in N=4 super-Yang-Mills theory
We construct, in the framework of the N=4 SYM theory, a supermultiplet of
twist-two conformal operators and study their renormalization properties. The
components of the supermultiplet have the same anomalous dimension and enter as
building blocks into multi-particle quasipartonic operators. The latter are
determined by the condition that their twist equals the number of elementary
constituent fields from which they are built. A unique feature of the N=4 SYM
is that all quasipartonic operators with different SU(4) quantum numbers fall
into a single supermultiplet. Among them there is a subsector of the operators
of maximal helicity, which has been known to be integrable in the multi-color
limit in QCD, independent of the presence of supersymmetry. In the N=4 SYM
theory, this symmetry is extended to the whole supermultiplet of quasipartonic
operators and the one-loop dilatation operator coincides with a Hamiltonian of
integrable SL(2|4) Heisenberg spin chain.Comment: 45 pages, Latex, 4 figure
Search for astrophysical electron antineutrinos in Super-Kamiokande with 0.01wt% gadolinium-loaded water
We report the first search result for the flux of astrophysical electron
antineutrinos for energies O(10) MeV in the gadolinium-loaded Super-Kamiokande
(SK) detector. In June 2020, gadolinium was introduced to the ultra-pure water
of the SK detector in order to detect neutrons more efficiently. In this new
experimental phase, SK-Gd, we can search for electron antineutrinos via inverse
beta decay with efficient background rejection and higher signal efficiency
thanks to the high efficiency of the neutron tagging technique. In this paper,
we report the result for the initial stage of SK-Gd with a exposure at 0.01% Gd mass concentration. No significant excess
over the expected background in the observed events is found for the neutrino
energies below 31.3 MeV. Thus, the flux upper limits are placed at the 90%
confidence level. The limits and sensitivities are already comparable with the
previous SK result with pure-water () owing
to the enhanced neutron tagging
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