688 research outputs found
Mass campaigns with antimalarial drugs: a modelling comparison of artemether-lumefantrine and DHA-piperaquine with and without primaquine as tools for malaria control and elimination
Antimalarial drugs are a powerful tool for malaria control and elimination.
Artemisinin-based combination therapies (ACTs) can reduce transmission when
widely distributed in a campaign setting. Modelling mass antimalarial campaigns
can elucidate how to most effectively deploy drug-based interventions and
quantitatively compare the effects of cure, prophylaxis, and
transmission-blocking in suppressing parasite prevalence. A previously
established agent-based model that includes innate and adaptive immunity was
used to simulate malaria infections and transmission. Pharmacokinetics of
artemether, lumefantrine, dihydroartemisinin, piperaquine, and primaquine were
modelled with a double-exponential distribution-elimination model including
weight-dependent parameters and age-dependent dosing. Drug killing of asexual
parasites and gametocytes was calibrated to clinical data. Mass distribution of
ACTs and primaquine was simulated with seasonal mosquito dynamics at a range of
transmission intensities. A single mass campaign with antimalarial drugs is
insufficient to permanently reduce malaria prevalence when transmission is
high. Current diagnostics are insufficiently sensitive to accurately identify
asymptomatic infections, and mass-screen-and-treat campaigns are much less
efficacious than mass drug administrations. Improving campaign coverage leads
to decreased prevalence one month after the end of the campaign, while
increasing compliance lengthens the duration of protection against reinfection.
Use of a long-lasting prophylactic as part of a mass drug administration
regimen confers the most benefit under conditions of high transmission and
moderately high coverage. Addition of primaquine can reduce prevalence but
exerts its largest effect when coupled with a long-lasting prophylactic.Comment: 14 pages, 5 figure
Optimal population-level infection detection strategies for malaria control and elimination in a spatial model of malaria transmission
Mass campaigns with antimalarial drugs are potentially a powerful tool for
local elimination of malaria, yet current diagnostic technologies are
insufficiently sensitive to identify all individuals who harbor infections. At
the same time, overtreatment of uninfected individuals increases the risk of
accelerating emergence of drug resistance and losing community acceptance.
Local heterogeneity in transmission intensity may allow campaign strategies
that respond to index cases to successfully target subpatent infections while
simultaneously limiting overtreatment. While selective targeting of hotspots of
transmission has been proposed as a strategy for malaria control, such
targeting has not been tested in the context of malaria elimination. Using
household locations, demographics, and prevalence data from a survey of four
health facility catchment areas in southern Zambia and an agent-based model of
malaria transmission and immunity acquisition, a transmission intensity was fit
to each household based on neighborhood age-dependent malaria prevalence. A set
of individual infection trajectories was constructed for every household in
each catchment area, accounting for heterogeneous exposure and immunity.
Various campaign strategies (mass drug administration, mass screen and treat,
focal mass drug administration, snowball reactive case detection, pooled
sampling, and a hypothetical serological diagnostic) were simulated and
evaluated for performance at finding infections, minimizing overtreatment,
reducing clinical case counts, and interrupting transmission. For malaria
control, presumptive treatment leads to substantial overtreatment without
additional morbidity reduction under all but the highest transmission
conditions. Selective targeting of hotspots with drug campaigns is an
ineffective tool for elimination due to limited sensitivity of available field
diagnostics
Malaria elimination campaigns in the Lake Kariba region of Zambia: a spatial dynamical model
Background As more regions approach malaria elimination, understanding how
different interventions interact to reduce transmission becomes critical. The
Lake Kariba area of Southern Province, Zambia, is part of a multi-country
elimination effort and presents a particular challenge as it is an
interconnected region of variable transmission intensities.
Methods In 2012-13, six rounds of mass-screen-and-treat drug campaigns were
carried out in the Lake Kariba region. A spatial dynamical model of malaria
transmission in the Lake Kariba area, with transmission and climate modeled at
the village scale, was calibrated to the 2012-13 prevalence survey data, with
case management rates, insecticide-treated net usage, and drug campaign
coverage informed by surveillance. The model was used to simulate the effect of
various interventions implemented in 2014-22 on reducing regional transmission,
achieving elimination by 2022, and maintaining elimination through 2028.
Findings The model captured the spatio-temporal trends of decline and rebound
in malaria prevalence in 2012-13 at the village scale. Simulations predicted
that elimination required repeated mass drug administrations coupled with
simultaneous increase in net usage. Drug campaigns targeted only at high-burden
areas were as successful as campaigns covering the entire region.
Interpretation Elimination in the Lake Kariba region is possible through
coordinating mass drug campaigns with high-coverage vector control. Targeting
regional hotspots is a viable alternative to global campaigns when human
migration within an interconnected area is responsible for maintaining
transmission in low-burden areas
Facility for fast neutron irradiation tests of electronics at the ISIS spallation neutron source
The VESUVIO beam line at the ISIS spallation neutron source was set up for neutron irradiation tests in the neutron energy range above 10 MeV. The neutron flux and energy spectrum were shown, in benchmark activation measurements, to provide a neutron spectrum similar to the ambient one at sea level, but with an enhancement in intensity of a factor of 107. Such conditions are suitable for accelerated testing of electronic components, as was demonstrated here by measurements of soft error rates in recent technology field programable gate arrays
Zero permeability and zero permittivity band gaps in 1D metamaterial photonic crystals
We consider layered heterostructures combining ordinary positive index
materials and dispersive metamaterials. We show that these structures can
exhibit a new type of photonic gap around frequencies where either the magnetic
permeability \mu or the electric permittivity \epsilon of the metamaterial is
zero. Although the interface of a semi-infinite medium with zero refractive
index (a condition attained either when \mu= 0 or when \epsilon= 0) is known to
give full reflectivity for all incident polarizations, here we show that a gap
corresponding to \mu = 0 occurs only for TE polarized waves, whereas a gap
corresponding to \epsilon = 0 occurs only for TM polarized waves. These band
gaps are scale-length invariant and very robust against disorder, although they
may disappear for the particular case of propagation along the stratification
direction.Comment: 7 pages, 5 figure
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Memory in autism spectrum disorder: a meta-analysis of experimental studies
To address inconsistencies in the literature on memory in Autism Spectrum Disorder (ASD), we report the first ever meta-analysis of short-term (STM) and episodic long-term (LTM) memory in ASD, evaluating the effects of type of material, type of retrieval and the role of inter-item relations. Analysis of 64 studies comparing individuals with ASD and typical development (TD) showed greater difficulties in ASD compared to TD individuals in STM (Hedges’ g=-0.53 [95%CI -0.90; -0.16], p=.005, I²=96%) compared to LTM (g=-0.30 [95%CI -0.42; -0.17], p<.00001, I²=24%), a small difficulty in verbal LTM (g=-0.21, p=.01), contrasting with a medium difficulty for visual LTM (g= -0.41, p=.0002) in ASD compared to TD individuals. We also found a general diminution in free recall compared to cued recall and recognition (LTM, free recall: g=-0.38, p<.00001, cued recall: g=-0.08, p=.58, recognition: g=-0.15, p=.16; STM, free recall: g=-0.59, p=.004, recognition: g=-0.33, p=.07). We discuss these results in terms of their relation to semantic memory. The limited diminution in verbal LTM and preserved overall recognition and cued recall (supported retrieval) may result from a greater overlap of these tasks with semantic long-term representations which are overall preserved in ASD. By contrast, difficulties in STM or free recall may result from less overlap with the semantic system or may involve additional cognitive operations and executive demands. These findings highlight the need to support STM functioning in ASD and acknowledge the potential benefit of using verbal materials at encoding and broader forms of memory support at retrieval to enhance performance
Mesures de facteurs spectroscopiques de 61Ni par réaction (d, p) en régime sous-coulombien
Nous avons utilisé la réaction (d, p) en régime sous-coulombien pour mesurer les facteurs spectroscopiques de deux états excités par transferts l = 0 et l = 2 dans 61Ni au voisinage de 4,8 MeV. Nos résultats confirment que la règle de somme pour le remplissage des couches 3s1/2 et 2d n'est satisfaite qu'à 50 % dans 61Ni
B-physics with Wilson fermions
We report the final results of the ALPHA collaboration for some B-physics
observables: , and . We employ CLS configurations with 2
flavors of improved Wilson fermions in the sea and pion masses ranging
down to 190 MeV. The b-quark is treated in HQET to order . The
renormalization, the matching and the improvement were performed
non-perturbatively, and three lattice spacings reaching fm are used
in the continuum extrapolation
The b-quark mass from non-perturbative Heavy Quark Effective Theory at
We report our final estimate of the b-quark mass from lattice QCD
simulations using Heavy Quark Effective Theory non-perturbatively matched to
QCD at . Treating systematic and statistical errors in a conservative
manner, we obtain GeV after an extrapolation to the physical point.Comment: 15 pages including figures and tables; as published in Phys.Lett.B /
typo in table 4 corrected / footnote 1 expande
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