256 research outputs found
Localization in Strongly Chaotic Systems
We show that, in the semiclassical limit and whenever the elements of the
Hamiltonian matrix are random enough, the eigenvectors of strongly chaotic
time-independent systems in ordered bases can on average be exponentially
localized across the energy shell and decay faster than exponentially outside
the energy shell. Typically however, matrix elements are strongly correlated
leading to deviations from such behavior.Comment: RevTeX, 5 pages + 3 postscript figures, submitted to Phys. Rev. Let
Excited Random Walk in One Dimension
We study the excited random walk, in which a walk that is at a site that
contains cookies eats one cookie and then hops to the right with probability p
and to the left with probability q=1-p. If the walk hops onto an empty site,
there is no bias. For the 1-excited walk on the half-line (one cookie initially
at each site), the probability of first returning to the starting point at time
t scales as t^{-(2-p)}. Although the average return time to the origin is
infinite for all p, the walk eats, on average, only a finite number of cookies
until this first return when p<1/2. For the infinite line, the probability
distribution for the 1-excited walk has an unusual anomaly at the origin. The
positions of the leftmost and rightmost uneaten cookies can be accurately
estimated by probabilistic arguments and their corresponding distributions have
power-law singularities near the origin. The 2-excited walk on the infinite
line exhibits peculiar features in the regime p>3/4, where the walk is
transient, including a mean displacement that grows as t^{nu}, with nu>1/2
dependent on p, and a breakdown of scaling for the probability distribution of
the walk.Comment: 14 pages, 13 figures, 2-column revtex4 format, for submission to J.
Phys.
Quality of care for pregnant women and newborns—the WHO vision
In 2015, as we review progress towards Millennium Development Goals (MDGs), despite significant progress in reduction of mortality, we still have unacceptably high numbers of maternal and newborn deaths globally. Efforts over the past decade to reduce adverse outcomes for pregnant women and newborns have been directed at increasing skilled birth attendance.1,2 This has resulted in higher rates of births in health facilities in all regions.3 The proportion of deliveries reportedly attended by skilled health personnel in developing countries rose from 56% in 1990 to 68% in 2012.4 With increasing utilisation of health services, a higher proportion of avoidable maternal and perinatal mortality and morbidity have moved to health facilities. In this context, poor quality of care (QoC) in many facilities becomes a paramount roadblock in our quest to end preventable mortality and morbidity
Uptake of home-based voluntary HIV testing in sub-Saharan Africa: a systematic review and meta-analysis
Improving access to HIV testing is a key priority in scaling up HIV treatment and prevention services. Home-based voluntary counselling and testing (HBT) as an approach to delivering wide-scale HIV testing is explored here
Cornering Solar Radiative-Zone Fluctuations with KamLAND and SNO Salt
We update the best constraints on fluctuations in the solar medium deep
within the solar Radiative Zone to include the new SNO-salt solar neutrino
measurements. We find that these new measurements are now sufficiently precise
that neutrino oscillation parameters can be inferred independently of any
assumptions about fluctuation properties. Constraints on fluctuations are also
improved, with amplitudes of 5% now excluded at the 99% confidence level for
correlation lengths in the range of several hundred km. Because they are
sensitive to correlation lengths which are so short, these solar neutrino
results are complementary to constraints coming from helioseismology.Comment: 4 pages, LaTeX file using RevTEX4, 6 figures include
Physical properties and biocompatibility of Chitosan/soy blended membranes
Blends of polysaccharides and proteins are a source for the development of novel materials with interesting and tailorable properties, with potential to be used in a range of biomedical applications. in this work a series of blended membranes composed by chitosan and soy protein isolate was prepared by solvent casting methodology. in addition, cross-linking was performed in situ with glutaraldehyde solutions in the range 5 × 10–3 – 0.1 M. Furthermore, the influence of the composition and cross-linking on the degradation behaviour, water uptake and cell adhesion was investigated. The obtained results showed that the incorporation of chitosan, associated to network formation by cross linking, promoted a slight decrease of water absorption and a slower degradability of the membranes. Moreover, direct contact biocompatibility studies, with L929 cells, indicate that the cross-linking enhances the capability of the material to support cell growth.Fundação para a Ciência e a Tecnologia (FCT
Factors affecting haemoglobin dynamics in African children with acute uncomplicated Plasmodium falciparum malaria treated with single low dose primaquine or placebo
Background: Single low-dose primaquine (SLDPQ) effectively blocks the transmission of Plasmodium falciparum malaria, but anxiety remains regarding its haemolytic potential in patients with glucose-6-phopshate dehydrogenase (G6PD) deficiency. We, therefore, examined the independent effects of several factors on haemoglobin (Hb) dynamics in falciparum-infected children with a particular interest in SLDPQ and G6PD status. Methods: This randomised, double-blind, placebo-controlled, safety trial was conducted in Congolese and Ugandan children aged 6 months–11 years with acute uncomplicated P. falciparum and day (D) 0 Hbs ≥ 6 g/dL who were treated with age-dosed SLDPQ/placebo and weight-dosed artemether lumefantrine (AL) or dihydroartemisinin piperaquine (DHAPP). Genotyping defined G6PD (G6PD c.202T allele), haemoglobin S (HbS), and α-thalassaemia status. Multivariable linear and logistic regression assessed factor independence for continuous Hb parameters and Hb recovery (D42 Hb > D0 Hb), respectively. Results: One thousand one hundred thirty-seven children, whose median age was 5 years, were randomised to receive: AL + SLDPQ (n = 286), AL + placebo (286), DHAPP + SLDPQ (283), and DHAPP + placebo (282). By G6PD status, 284 were G6PD deficient (239 hemizygous males, 45 homozygous females), 119 were heterozygous females, 418 and 299 were normal males and females, respectively, and 17 were of unknown status. The mean D0 Hb was 10.6 (SD 1.6) g/dL and was lower in younger children with longer illnesses, lower mid-upper arm circumferences, splenomegaly, and α-thalassaemia trait, who were either G6PDd or heterozygous females. The initial fractional fall in Hb was greater in younger children with higher D0 Hbs and D0 parasitaemias and longer illnesses but less in sickle cell trait. Older G6PDd children with lower starting Hbs and greater factional falls were more likely to achieve Hb recovery, whilst lower D42 Hb concentrations were associated with younger G6PD normal children with lower fractional falls, sickle cell disease, α-thalassaemia silent carrier and trait, and late treatment failures. Ten blood transfusions were given in the first week (5 SLDPQ, 5 placebo). Conclusions: In these falciparum-infected African children, posttreatment Hb changes were unaffected by SLDPQ, and G6PDd patients had favourable posttreatment Hb changes and a higher probability of Hb recovery. These reassuring findings support SLDPQ deployment without G6PD screening in Africa
Theory and Applications of X-ray Standing Waves in Real Crystals
Theoretical aspects of x-ray standing wave method for investigation of the
real structure of crystals are considered in this review paper. Starting from
the general approach of the secondary radiation yield from deformed crystals
this theory is applied to different concreat cases. Various models of deformed
crystals like: bicrystal model, multilayer model, crystals with extended
deformation field are considered in detailes. Peculiarities of x-ray standing
wave behavior in different scattering geometries (Bragg, Laue) are analysed in
detailes. New possibilities to solve the phase problem with x-ray standing wave
method are discussed in the review. General theoretical approaches are
illustrated with a big number of experimental results.Comment: 101 pages, 43 figures, 3 table
Dielectric and conductivity relaxation in mixtures of glycerol with LiCl
We report a thorough dielectric characterization of the alpha relaxation of
glass forming glycerol with varying additions of LiCl. Nine salt concentrations
from 0.1 - 20 mol% are investigated in a frequency range of 20 Hz - 3 GHz and
analyzed in the dielectric loss and modulus representation. Information on the
dc conductivity, the dielectric relaxation time (from the loss) and the
conductivity relaxation time (from the modulus) is provided. Overall, with
increasing ion concentration, a transition from reorientationally to
translationally dominated behavior is observed and the translational ion
dynamics and the dipolar reorientational dynamics become successively coupled.
This gives rise to the prospect that by adding ions to dipolar glass formers,
dielectric spectroscopy may directly couple to the translational degrees of
freedom determining the glass transition, even in frequency regimes where
usually strong decoupling is observed.Comment: 8 pages, 7 figure
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