1,493 research outputs found
Update on the current status of onchocerciasis in Cote d’Ivoire following 40 years of intervention: Progress and challenges
Background
Onchocerciasis control in Côte d’Ivoire started with aerial insecticide spraying in 1974 and continued with community directed treatment with ivermectin (CDTi) from 1992 to the present. Onchocerciasis and lymphatic filariasis (LF) are co-endemic in 46 of the 81 health districts in the country. Fourteen and 12 districts are endemic for only LF or onchocerciasis, respectively. This paper aims to review the impact of past interventions on onchocerciasis in Côte d’Ivoire between 1975 and 2013, and review plans for disease elimination.
Methods
We reviewed microfilaria (MF, skin snip) prevalence and community microfilarial load (CMFL) data from published reports from 53 health districts during two major epidemiological assessment periods. Data from 1975 through 1991 provided information on the impact of vector control, and data from 1992 through 2016 provided information on the impact of CDTi.
Results
Weekly aerial insecticide spraying in 8 endemic districts between 1975 and 1991 reduced the overall MF prevalence by 68.1% from 43.5% to 13.9%. The CMFL also decreased in 7 out of 8 surveyed communities by 95.2% from 9.24 MF/snip to 0.44 MF/snip. Ivermectin distribution started in 1992. The coverage targets for control (65% of the total population) was reached in most endemic districts, and some areas achieved 80% coverage. Two sets of surveys were conducted to assess the impact of CDTi. Results from the first repeat surveys showed a significant decrease in overall MF prevalence (by 75.7%, from 41.6% to 10.1%). The second follow-up evaluation showed further improvement in most endemic districts and also documented major reductions in CMFL compared to baseline.
Conclusions
Extensive data collected over many years document the very significant impact of interventions conducted by the National Onchocerciasis and other Eyes Diseases Control Programme during challenging times with periods of civil unrest. The Health Ministry has now integrated efforts to control neglected tropical diseases and adopted the goal of onchocerciasis elimination
Is there a Phase Transition to the Flux Lattice State?
The sharp drops in the resistance and magnetization which are usually
attributed to a phase transition from the vortex liquid state to a crystal
state are explained instead as a crossover between three and two dimensional
behavior, which occurs when the phase coherence length in the liquid becomes
comparable to the sample thickness. Estimates of the width of the crossover
region and the phase coherence length scales are in agreement with experiment.Comment: 4 pages, RevTe
Metastable Dynamics above the Glass Transition
The element of metastability is incorporated in the fluctuating nonlinear
hydrodynamic description of the mode coupling theory (MCT) of the liquid-glass
transition. This is achieved through the introduction of the defect density
variable into the set of slow variables with the mass density and
the momentum density . As a first approximation, we consider the case
where motions associated with are much slower than those associated with
. Self-consistently, assuming one is near a critical surface in the MCT
sense, we find that the observed slowing down of the dynamics corresponds to a
certain limit of a very shallow metastable well and a weak coupling between
and . The metastability parameters as well as the exponents
describing the observed sequence of time relaxations are given as smooth
functions of the temperature without any evidence for a special temperature. We
then investigate the case where the defect dynamics is included. We find that
the slowing down of the dynamics corresponds to the system arranging itself
such that the kinetic coefficient governing the diffusion of the
defects approaches from above a small temperature-dependent value .Comment: 38 pages, 14 figures (6 figs. are included as a uuencoded tar-
compressed file. The rest is available upon request.), RevTEX3.0+eps
Modelling of content-aware indicators for effective determination of shot boundaries in compressed MPEG videos
In this paper, a content-aware approach is proposed to design multiple test conditions for shot cut detection, which are organized into a multiple phase decision tree for abrupt cut detection and a finite state machine for dissolve detection. In comparison with existing approaches, our algorithm is characterized with two categories of content difference indicators and testing. While the first category indicates the content changes that are directly used for shot cut detection, the second category indicates the contexts under which the content change occurs. As a result, indications of frame differences are tested with context awareness to make the detection of shot cuts adaptive to both content and context changes. Evaluations announced by TRECVID 2007 indicate that our proposed algorithm achieved comparable performance to those using machine learning approaches, yet using a simpler feature set and straightforward design strategies. This has validated the effectiveness of modelling of content-aware indicators for decision making, which also provides a good alternative to conventional approaches in this topic
Graphene Overcoats for Ultra-High Storage Density Magnetic Media
Hard disk drives (HDDs) are used as secondary storage in a number of digital
electronic devices owing to low cost (0.1\\sim^2<<\sim>^2$
Improved perturbation theory in the vortex liquids state of type II superconductors
We develop an optimized perturbation theory for the Ginzburg - Landau
description of thermal fluctuations effects in the vortex liquids. Unlike the
high temperature expansion which is asymptotic, the optimized expansion is
convergent. Radius of convergence on the lowest Landau level is in
2D and in 3D. It allows a systematic calculation of magnetization
and specific heat contributions due to thermal fluctuations of vortices in
strongly type II superconductors to a very high precision. The results are in
good agreement with existing Monte Carlo simulations and experiments.
Limitations of various nonperturbative and phenomenological approaches are
noted. In particular we show that there is no exact intersection point of the
magnetization curves both in 2D and 3D.Comment: 24 pages, 9 figure
Publisher Correction: Graphene overcoats for ultra-high storage density magnetic media.
Publisher Correction: Graphene overcoats for ultra-high storage density magnetic media
Numerical studies of the phase diagram of layered type II superconductors in a magnetic field
We report on simulations of layered superconductors using the
Lawrence-Doniach model in the framework of the lowest Landau level
approximation. We find a first order phase transition with a dependence
which agrees very well with the experimental ``melting'' line in YBaCuO. The
transition is not associated with vortex lattice melting, but separates two
vortex liquid states characterised by different degrees of short-range
crystalline order and different length scales of correlations between vortices
in different layers. The transition line ends at a critical end-point at low
fields. We find the magnetization discontinuity and the location of the lower
critical magnetic field to be in good agreement with experiments in YBaCuO.
Length scales of order parameter correlations parallel and perpendicular to the
magnetic field increase exponentially as 1/T at low temperatures. The dominant
relaxation time scales grow roughly exponentially with these correlation
lengths. We find that the first order phase transition persists in the presence
of weak random point disorder but can be suppressed entirely by strong
disorder. No vortex glass or Bragg glass state is found in the presence of
disorder. The consistency of our numerical results with various experimental
features in YBaCuO, including the dependence on anisotropy, and the temperature
dependence of the structure factor at the Bragg peaks in neutron scattering
experiments is demonstrated.Comment: 25 pages (revtex), 19 figures included, submitted to PR
Isolation and fine mapping of Rps6: An intermediate host resistance gene in barley to wheat stripe rust
A plant may be considered a nonhost of a pathogen if all known genotypes of a plant species are resistant to all known isolates of a pathogen species. However, if a small number of genotypes are susceptible to some known isolates of a pathogen species this plant maybe considered an intermediate host. Barley (Hordeum vulgare) is an intermediate host for Puccinia striiformis f. sp. tritici (Pst), the causal agent of wheat stripe rust. We wanted to understand the genetic architecture underlying resistance to Pst and to determine whether any overlap exists with resistance to the host pathogen, Puccinia striiformis f. sp. hordei (Psh). We mapped Pst resistance to chromosome 7H and show that host and intermediate host resistance is genetically uncoupled. Therefore, we designate this resistance locus Rps6. We used phenotypic and genotypic selection on F2:3 families to isolate Rps6 and fine mapped the locus to a 0.1 cM region. Anchoring of the Rps6 locus to the barley physical map placed the region on two adjacent fingerprinted contigs. Efforts are now underway to sequence the minimal tiling path and to delimit the physical region harbouring Rps6. This will facilitate additional marker development and permit identification of candidate genes in the region
Graphene overcoats for ultra-high storage density magnetic media
Hard disk drives (HDDs) are used as secondary storage in digital electronic devices owing to low cost and large data storage capacity. Due to the exponentially increasing amount of data, there is a need to increase areal storage densities beyond~1Tb/in^2. This requires the thickness of carbon overcoats (COCs) to be<2 nm. However, friction, wear, corrosion, and thermal stability are critical concerns below 2 nm, limiting current technology, and restricting COC integration with heat assisted magnetic recording technology (HAMR). Here we show that graphene-based overcoats can overcome all these limitations, and achieve two-fold reduction in friction and provide better corrosion and wear resistance than state-of-the-art COCs, while withstanding HAMR conditions. Thus, we expect that graphene overcoats may enable the development of 4-10 Tb/in^2 areal density HDDs when employing suitable recording technologies, such as HAMR and HAMR+bit patterned media
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