1,322 research outputs found
Efficacy and safety of praziquantel in preschool-aged children in an area co-endemic for Schistosoma mansoni and S. haematobium
BACKGROUND: In sub-Saharan Africa the recommended strategy to control schistosomiasis is preventive chemotherapy. Emphasis is placed on school-aged children, but in high endemicity areas, preschool-aged children are also at risk, and hence might need treatment with praziquantel. Since a pediatric formulation (e.g., syrup) is not available outside of Egypt, crushed praziquantel tablets are used, but the efficacy and safety of this treatment regimen is insufficiently studied.METHODOLOGY: We assessed the efficacy and safety of crushed praziquantel tablets among preschool-aged children (>6 years) in the Azaguié district, south Côte d'Ivoire, where Schistosoma mansoni and S. haematobium coexist. Using a cross-sectional design, children provided two stool and two urine samples before and 3 weeks after treatment. Crushed praziquantel tablets, mixed with water, were administered at a dose of 40 mg/kg. Adverse events were assessed and graded 4 and 24 hours posttreatment by interviewing mothers/guardians.PRINCIPAL FINDINGS: Overall, 160 preschool-aged children had at least one stool and one urine sample examined with duplicate Kato-Katz thick smears and a point-of-care circulating cathodic antigen (POC-CCA) cassette for S. mansoni, and urine filtration for S. haematobium diagnosis before and 3 weeks after praziquantel administration. According to the Kato-Katz and urine filtration results, we found high efficacy against S. mansoni (cure rate (CR), 88.6%; egg reduction rate (ERR), 96.7%) and S. haematobium (CR, 88.9%; ERR, 98.0%). POC-CCA revealed considerably lower efficacy against S. mansoni (CR, 53.8%). Treatment was generally well tolerated, but moderately severe adverse events (i.e., body and face inflammation), were observed in four Schistosoma egg-negative children. CONCLUSIONS/SIGNIFICANCE: Crushed praziquantel administered to preschool-aged children at a dose of 40 mg/kg is efficacious against S. mansoni and S. haematobium in a co-endemic setting of Côte d'Ivoire. Further research is required with highly sensitive diagnostic tools and safety must be investigated in more depth.TRIAL REGISTRATION: Controlled-Trials.com ISRCTN53172722
AdS_3 Partition Functions Reconstructed
For pure gravity in AdS_3, Witten has given a recipe for the construction of
holomorphically factorizable partition functions of pure gravity theories with
central charge c=24k. The partition function was found to be a polynomial in
the modular invariant j-function. We show that the partition function can be
obtained instead as a modular sum which has a more physical interpretation as a
sum over geometries. We express both the j-function and its derivative in terms
of such a sum.Comment: 9 page
Towards the Perfect X-ray Beam Splitter
X-ray free-electron lasers (FEL) deliver ultrabright X-ray pulses, but not
the sequences of phase-coherent pulses required for time-domain interferometry
and control of quantum states. For conventional split-and-delay schemes to
produce such sequences the challenge stems from extreme stability requirements
when splitting Angstrom wavelength beams where tiniest path length differences
introduce phase jitter. We describe an FEL mode based on selective electron
bunch degradation and transverse beam shaping in the accelerator, combined with
a self-seeded photon emission scheme. Instead of splitting the photon pulses
after their generation by the FEL, we split the electron bunch in the
accelerator, prior to photon generation, to obtain phase-locked X-ray pulses
with sub-femtosecond duration. Time-domain interferometry becomes possible,
enabling the concomitant program of classical and quantum optics experiments
with X-rays. The scheme leads to new scientific benefits of cutting-edge FELs
with attosecond and/or high-repetition rate capabilities, ranging from the
X-ray analog of Fourier transform infrared spectroscopy to damage-free
measurements
Absence of bound states for waveguides in 2D periodic structures
We study a Helmholtz-type spectral problem in a two-dimensional medium
consisting of a fully periodic background structure and a perturbation in form
of a line defect. The defect is aligned along one of the coordinate axes,
periodic in that direction (with the same periodicity as the background), and
bounded in the other direction. This setting models a so-called "soft-wall"
waveguide problem. We show that there are no bound states, i.e., the spectrum
of the operator under study contains no point spectrum.Comment: This is an updated version of our paper (in slightly different form
in Journal of Mathematical Physics). An anonymous reviewer kindly made us
aware that ref. 10 is not applicable in our situation. An application of the
theorem in ref. 10 would have proved the absence of singular continuous
spectrum also. Our result on the absence of point spectrum is not affected by
thi
Regenerative approaches for V/UHTS feeder links: system analysis and on-board complexity reduction
The dramatically increasing demand for high data rates necessitates the proper dimensioning of the feeder links of very or ultra high throughput satellite (V/UHTS) systems. However, because most of the current solutions rely on transparent payloads, the deployment of a very large number of spatially separated ground stations is necessary to support the total system bandwidth by enabling a full reuse of the scarce available uplink bandwidth. This approach has a significant impact on the complexity and the costs of the ground segment infrastructure. Regenerative payloads could be considered to avoid this design bottleneck. By allowing demodulation and decoding on-board the satellite, the favourable link budget conditions of feeder links compared to the user links can be exploited. Using a spectral efficient transmission technique, the number of ground stations required to support a target sum throughput can be notably reduced. Meanwhile, regenerative solutions have until now barely been used in V/UHTS payloads due to their high on-board power consumption. As a consequence, candidate solutions are proposed in this work to overcome this limitation. A non-coherent modulation technique, known as Differential Amplitude Phase Shift Keying (DAPSK), is introduced to avoid on-board carrier synchronization. Moreover, polar codes are considered to minimize the power consumption of the channel decoder. A preliminary analysis of the expected on-board power consumption compared to that of a standard DVB-S2 approach is conducted using available results in the open literature. Link performance is also evaluated via numerical simulations
Renormalization of Multiple -Zeta Values
In this paper we shall define the renormalization of the multiple -zeta
values (MZV) which are special values of multiple -zeta functions
when the arguments are all positive integers or all
non-positive integers. This generalizes the work of Guo and Zhang
(math.NT/0606076v3) on the renormalization of Euler-Zagier multiple zeta
values. We show that our renormalization process produces the same values if
the MZVs are well-defined originally and that these renormalizations of
MZV satisfy the -stuffle relations if we use shifted-renormalizations for
all divergent (i.e., ). Moreover, when \qup
our renormalizations agree with those of Guo and Zhang.Comment: 22 pages. This is a substantial revision of the first version. I
provide a new and complete proof of the fact that our renormalizations
satisfy the q-stuffle relations using the shifting principle of MqZV
Discontinuous Molecular Dynamics for Semi-Flexible and Rigid Bodies
A general framework for performing event-driven simulations of systems with
semi-flexible or rigid bodies interacting under impulsive torques and forces is
outlined. Two different approaches are presented. In the first, the dynamics
and interaction rules are derived from Lagrangian mechanics in the presence of
constraints. This approach is most suitable when the body is composed of
relatively few point masses or is semi-flexible. In the second method, the
equations of rigid bodies are used to derive explicit analytical expressions
for the free evolution of arbitrary rigid molecules and to construct a simple
scheme for computing interaction rules. Efficient algorithms for the search for
the times of interaction events are designed in this context, and the handling
of missed interaction events is discussed.Comment: 16 pages, double column revte
Specific Heat Study of Non-Fermi Liquid Behavior in CeNi_2Ge_2: Anomalous Peak in Quasi-Particle Density-of-States
To investigate the non-Fermi liquid (NFL) behavior in a nonalloyed system
CeNi_2Ge_2, we have measured the temperature and field dependences of the
specific heat C on a CeNi_2Ge_2 single crystal. The distinctive temperature
dependence of C/T (~a-b*T^(1/2)) is destroyed in almost the same manner for
both field directions of B//c-axis and B//a-axis. The overall behavior of
C(T,B) and the low-temperature upturn in magnetic susceptibility can be
reproduced, assuming an anomalous peak of the quasi-particle-band
density-of-states (DOS) at the Fermi energy possessing (epsilon)^(1/2) energy
dependence. Absence of residual entropy around T=0 K in B~0 T has been
confirmed by the magnetocaloric effect measurements, which are consistent with
the present model. The present model can also be applied to the NFL behavior in
CeCu_{5.9}Au_{0.1} using a ln(epsilon)-dependent peak in the DOS. Possible
origins of the peak in the DOS are discussed.Comment: 4 pages, LaTeX, using jpsj.sty, to be published in J. Phys. Soc. Jpn.
66 No. 10 (1997), 7 figures available at
http://494-475.phys.metro-u.ac.jp/ao/ceni2ge2.htm
A descriptive qualitative case study of the experiences, perceptions, and attitudes of pregnant women on Unguja island, Zanzibar, towards antischistosomal treatment
Many countries exclude pregnant and lactating women from mass drug administration (MDA) programmes with praziquantel against schistosomiasis due to historic safety concerns over drug use during gestation and breast feeding. More than 10 years of empirical evidence from the field and a growing body of dedicated research has prompted the World Health Organisation and schistosomiasis control initiatives to advocate the inclusion of this vulnerable group into MDA. This qualitative descriptive case study explored, over a five-week period, the subjective experiences, perceptions, opinions, and attitudes of pregnant women attending government supported clinics on Unguja island, United Republic of Tanzania, towards praziquantel use during pregnancy in MDA programmes. The aim of the study was to identify and determine how to overcome potential barriers to effective use of MDA medications during pregnancy. Additionally, it was to determine trusted communication channels for future messaging and discover behavioural and community opportunities to increase participation of pregnant women in future MDA efforts. A 60-minute, semi-structured qualitative interview was undertaken with 25 pregnant women recruited from 4 health centres on Unguja along with testing for Schistosoma haematobium infection. Using a modified-grounded theory approach, narrative data were transcribed, coded and analysed using a thematic analysis of the emergent themes. Women reported they rely on traditional home remedies to stay healthy during pregnancy. Influenced by their mothers, husbands and neighbours, women predominately made medication choices during pregnancy and breastfeeding based on what they heard at home. Most women had been excluded from government MDA programmes in the past due to pregnancy. Women valued healthcare services for antenatal education and pregnancy advice. Women reported they would trust and follow direction from healthcare providers about taking praziquantel during pregnancy. Antenatal clinics offer an excellent opportunity to educate and expand praziquantel treatment to this cohort. Efforts should be augmented with training for providers and behavioural education for the community as a whole and family members of pregnant women
A Holder Continuous Nowhere Improvable Function with Derivative Singular Distribution
We present a class of functions in which is variant
of the Knopp class of nowhere differentiable functions. We derive estimates
which establish \mathcal{K} \sub C^{0,\al}(\R) for 0<\al<1 but no is pointwise anywhere improvable to C^{0,\be} for any \be>\al.
In particular, all 's are nowhere differentiable with derivatives singular
distributions. furnishes explicit realizations of the functional
analytic result of Berezhnoi.
Recently, the author and simulteously others laid the foundations of
Vector-Valued Calculus of Variations in (Katzourakis), of
-Extremal Quasiconformal maps (Capogna and Raich, Katzourakis) and of
Optimal Lipschitz Extensions of maps (Sheffield and Smart). The "Euler-Lagrange
PDE" of Calculus of Variations in is the nonlinear nondivergence
form Aronsson PDE with as special case the -Laplacian.
Using , we construct singular solutions for these PDEs. In the
scalar case, we partially answered the open regularity problem of
Viscosity Solutions to Aronsson's PDE (Katzourakis). In the vector case, the
solutions can not be rigorously interpreted by existing PDE theories and
justify our new theory of Contact solutions for fully nonlinear systems
(Katzourakis). Validity of arguments of our new theory and failure of classical
approaches both rely on the properties of .Comment: 5 figures, accepted to SeMA Journal (2012), to appea
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