1,302 research outputs found
Breast-feeding and weaning practices in Venda, 1990
A stratified randOlll cluster survey, using a structured interview schedule, was performed to determine the prevalence, frequency and duration of breast-feeding alllong Venda mothers as well as the foods that Venda children commonly ate in their first 2 years of life. Nearly all children under 2 years old were being breast-fed and virtually all of these were fed on demand. Approximately 60% of infants under 3 months of age and virtually all others under 2 years old received supplementary foods daily. A further 30% ofinfants under the age of 3 months were given supplementary water daily. Forty per cent of infants under 3 months old and virtually all in the other age groups were given carbohydrates daily. Protein foods, vitamin mineral and high-energy sources were given less frequently. Only 12% in the 6 - 11-month age group and 21% in the 12 - 23-111onth age group received a balanced diet daily. A significant proportion of children in all age groups received only carbohydrates over and above breast-milk. Traditional xnixes were infrequently given. More research is needed to assess actual breast-milk production by mothers whose children are being fed supplelllentary foods. The effect of socio-economic status on weaning practices and that of weaning practices on nutritional status need to be investigated. Food supplelllentation and nutrition education progralllllles need to be intensified
The new control system of the SPS target sector
The SPS, the Super Proton Synchrotron at CERN, is an accelerator originally designed and commissioned in 1976 for protons. The control system of the SPS target stations, beam absorbers and other aperture limiting devices was developed in the seventies. It was mainly based on home made electronics and equipment dependent software. With time, this electronics has become obsolete, difficult to maintain in operation and not suitable for integration into a modern control system. In 1997, a project was set up to modernise the electronics and the related software. The new control system is largely based on standard industrial hardware and software components. SIEMENS Simatic S7-300 programmable logic controllers have been used as equipment controllers and connected through PROFIBUS to a Windows-NT front-end PC running the SIEMENS WinCC SCADA package which acts as local controller and remote access gateway. This fully industrial solution has been successfully integrated into the actual SPS accelerator control infrastructure and is open to other industrial communication protocols. The design, development and realisation of the selected solution have been outsourced to industry
Leptogenesis, neutrino masses and gauge unification
Leptogenesis is considered in its natural context where Majorana neutrinos
fit in a gauge unification scheme and therefore couple to some extra gauge
bosons. The masses of some of these gauge bosons are expected to be similar to
those of the heavy Majorana particles, and this can have important consequences
for leptogenesis. In fact, the effect can go both ways. Stricter bounds are
obtained on one hand due to the dilution of the CP-violating effect by new
decay and scattering channels, while, in a re-heating scheme, the presence of
gauge couplings facilitates the re-population of the Majorana states. The
latter effect allows in particular for smaller Dirac couplings.Comment: 11pages, 7 figures. v2: definition of the lepton asymmetry corrected,
small numerical changes for the baryon number, conclusion does not change;
typos corrected and references adde
Commissioning of the Control System for the LHC Beam Dump Kicker System
The beam dumping system of the Large Hadron Collider (LHC) provides a loss-free fast extraction of the circulating beams. It consists per ring of 15 extraction kickers, followed by 15 septum magnets, 10 dilution kickers and an external absorber. A dump request can occur at any moment during the operation of the collider, from injection energy up to collision energy. All kickers must fire synchronously with the beam abort gap to properly extract the whole beam in one single turn into the extraction channel. Incorrect operation of the extraction kickers can lead to beam losses and severe damage to the machine. The control system of the LHC beam dump kickers is based on a modular architecture composed of 4 different sub-systems, each with a specific function, in order to detect internal failures, to ensure a correct extraction trajectory over the whole LHC operational range, to synchronise and distribute dumps requests, and to analyse the transient signals recorded during the beam dumping process. The control architecture is presented and the different steps performed for its validation, from the individual sub-systems tests to the final commissioning with beam, are describe
Automatic conditioning of the LHC injection kickers
The LHC injection systems, located near the interaction regions 2 and 8, comprise 4 fast pulsed kicker magnets (MKI) per ring to bring the beam onto the orbit. Each magnet is housed in a separate vacuum tank. Their nominal operating voltage is 54 kV, and the nominal pulse length 7.86 µs. To prepare these magnets for operation they are once assembled and baked out, gradually subjected to higher and higher voltages and greater pulse lengths, until their voltage holding capability is sufficiently beyond the nominal operating conditions. In the past this "conditioning" was carried out manually, and thus a manpower-intensive, and also technically not optimal procedure. To overcome these drawbacks a program has been developed, running in a Programmable Logic Controller (PLC), which has been used to condition the full suite of LHC injection kickers automatically
Dantu blood group erythrocytes form large Plasmodium falciparum rosettes less commonly
Dantu erythrocytes, which express a hybrid glycophorin B/A protein, are protective against severe malaria. Recent studies have shown that Dantu impairs Plasmodium falciparum invasion by increasing erythrocyte membrane tension, but its effects on pathological host–parasite adhesion interactions such as rosetting, the binding of uninfected erythrocytes to P. falciparum–infected erythrocytes, have not been investigated previously. The expression of several putative host rosetting receptors—including glycophorin A (GYPA), glycophorin C (GYPC), complement receptor 1 (CR1), and band 3, which complexes with GYPA to form the Wrightb blood group antigen—are altered on Dantu erythrocytes. Here, we compare receptor expression, and rosetting at both 1 hour and 48 hours after mixing with mature trophozoite-stage Kenyan laboratory–adapted P. falciparum strain 11019 parasites in Dantu and non-Dantu erythrocytes. Dantu erythrocytes showed lower staining for GYPA and CR1, and greater staining for band 3, as observed previously, whereas Wrightb and GYPC staining did not vary significantly. No significant between-genotype differences in rosetting were seen after 1 hour, but the percentage of large rosettes was significantly less in both Dantu heterozygous (mean, 16.4%; standard error of the mean [SEM], 3.2) and homozygous donors (mean, 15.4%; SEM, 1.4) compared with non-Dantu erythrocytes (mean, 32.9%; SEM, 7.1; one-way analysis of variance, P = 0.025) after 48 hours. We also found positive correlations between erythrocyte mean corpuscular volume (MCV), the percentage of large rosettes (Spearman’s rs = 0.5970, P = 0.0043), and mean rosette size (rs = 0.5206, P = 0.0155). Impaired rosetting resulting from altered erythrocyte membrane receptor expression and reduced MCV might add to the protective effect of Dantu against severe malaria
Large scale flow effects, energy transfer, and self-similarity on turbulence
The effect of large scales on the statistics and dynamics of turbulent
fluctuations is studied using data from high resolution direct numerical
simulations. Three different kinds of forcing, and spatial resolutions ranging
from 256^3 to 1024^3, are being used. The study is carried out by investigating
the nonlinear triadic interactions in Fourier space, transfer functions,
structure functions, and probability density functions. Our results show that
the large scale flow plays an important role in the development and the
statistical properties of the small scale turbulence. The role of helicity is
also investigated. We discuss the link between these findings and
intermittency, deviations from universality, and possible origins of the
bottleneck effect. Finally, we briefly describe the consequences of our results
for the subgrid modeling of turbulent flows
Spin-polarized oxygen hole states in cation deficient La(1-x)CaxMnO(3+delta)
When holes are doped into a Mott-Hubbard type insulator, like lightly doped
manganites of the La(1-x)CaxMnO3 family, the cooperative Jahn-Teller
distortions and the appearance of orbital ordering require an arrangement of
Mn(3+)/Mn(4+) for the establishment of the insulating canted antiferromagnetic
(for x<=0.1), or of the insulating ferromagnetic (for 0.1<x<= 0.2) ground
state. In the present work we provide NMR evidence about a novel and at the
same time puzzling effect in La(1-x)CaxMnO(3+delta) systems with cation
deficience. We show that in the low Ca-doping regime, these systems exhibit a
very strong hyperfine field at certain La nuclear sites, which is not present
in the stoichiometric compounds. Comparison of our NMR results with recent
x-ray absorption data at the Mn K edge, suggests the formation of a
spin-polarized hole arrangement on the 2p oxygen orbitals as the origin of this
effect.Comment: 10 pages, 4 Figures, submitted to PR
A Proof Assistant Based Formalisation of a Subset of Sequential Core Erlang
We present a proof-assistant-based formalisation of a subset of Erlang, intended to serve as a base for proving refactorings correct. After discussing how we reused concepts from related work, we show the syntax and semantics of our formal description, including the abstractions involved (e.g. the concept of a closure). We also present essential properties of the formalisation (e.g. determinism) along with the summary of their machine-checked proofs. Finally, we prove expression pattern equivalences which can be interpreted as simple local refactorings
Effect of ultrasound on bone fracture healing:A computational bioregulatory model
peer reviewedBone healing is a complex biological procedure in which several cellular actions, directed by biochemical and mechanical signals, take place. Experimental studies have shown that ultrasound accelerates bone ossification and has a multiple influence on angiogenesis. In this study a mathematical model predicting bone healing under the presence of ultrasound is demonstrated. The primary objective is to account for the ultrasound effect on angiogenesis and more specifically on the transport of the Vascular Endothelial Growth Factor (VEGF). Partial differential equations describing the spatiotemporal evolution of cells, growth factors, tissues and ultrasound acoustic pressure and velocity equations determining the development of the blood vessel network constitute the present model. The effect of the ultrasound characteristics on angiogenesis and bone healing is investigated by applying different boundary conditions of acoustic pressure at the periosteal region of the bone model, which correspond to different intensity values. The results made clear that ultrasound enhances angiogenesis mechanisms during bone healing. The proposed model could be regarded as a step towards the monitoring of the effect of ultrasound on bone regeneration. © 2018Action “Supporting Postdoctoral Researchers” of the Operational Program “Education and Lifelong Learning” (Action’s Beneficiary: General Secretariat for Research and Technology); Greek State (PE8-3347
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