Mortalité néonatale au centre hospitalier universitaire de Tengandogo, Ouagadougou, Burkina Faso: une étude de cohorte retrospective: Neonatal mortality at Tengandogo University Hospital, Ouagadougou, Burkina Faso: a retrospective cohort study

Introduction: Selon l’organisation mondiale de la santé, les décès néonataux représentent 41% de la mortalité infanto-juvénile. L’Afrique subsaharienne a le taux de mortalité néonatale le plus élevé à 28‰. L’objectif de l’étude était de mesurer le taux de mortalité néonatale et d’identifier les facteurs associés au décès au Centre hospitalier universitaire de Tengandogo, Ouagadougou, Burkina Faso. Méthodes: Les nouveaux nés de 0 à 28 jours, hospitalisés entre le 1er janvier 2013 et le 31 décembre 2017 ont été inclus dans cette étude de cohorte rétrospective au service de néonatologie et de pédiatrie. Les informations ont été extraites à partir des dossiers cliniques. La survie a été estimée par la méthode de Kaplan Meier. Un modèle de Cox a permis d’identifier les facteurs associés. Résultats: Au total 641 nouveau-nés ont été inclus. Les enfants admis dès le premier jour de leur naissance représentaient 80%. La durée médiane de séjour était de 6 jours avec un intervalle interquartile de 3-12 jours. Les principaux diagnostics étaient la prématurité (36,05%), les infections néonatales (33,23%) et l’asphyxie (17,86%). Le taux de mortalité néonatale était de 22,25 pour 1000 personnes jours. Après ajustement, le poids de naissance inferieur 1500gramme (HRa = 4,13 ; IC 95% (2,58-6,67)) et la notion de réanimation à la naissance (HRa2,62 ; IC 95% [1,64-4,39)) étaient les facteurs de risque. Conclusion: Le taux de mortalité néonatale reste élevé. Le suivi prénatal, la prévention des infections, le renforcement des moyens de réanimation et la compétence des acteurs sont essentiels pour réduire ce taux. Introduction: According to the World Health Organization, neonatal deaths account for 41% of infant and child mortality. Sub-Saharan Africa has the highest neonatal mortality rate at 28‰. The objective of the study was to measure the neonatal mortality rate and identify factors associated with death at the Tengandogo University Hospital, Ouagadougou, Burkina Faso. Method: New-borns aged 0 to 28 days, hospitalised between 1 January 2013 and 31 December 2017 were included in this retrospective cohort study in the neonatology and paediatrics department. Information was extracted from clinical records. Survival was estimated by the Kaplan Meier method. A Cox model was used to identify associated factors. Results: A total of 641 new-borns were included. Children admitted on the first day of birth accounted for 80%. The median length of stay was 6 days with an interquartile range of 3-12 days. The main diagnoses were prematurity (36.05%), neonatal infections (33.23%) and asphyxia (17.86%). The neonatal mortality rate was 22.25 per 1000 person days. After adjustment, birth weight below 1500 grams (HRa = 4.13; 95% CI (2.58-6.67)) and the notion of resuscitation at birth (HRa2.62; 95% CI (1.64-4.39)) were the risk factors. Conclusion: The neonatal mortality rate remains high. Prenatal follow-up, infection prevention, strengthening of resuscitation resources and competence of actors are essential to reduce this rate

Consistent model of magnetism in ferropnictides

The discovery of superconductivity in LaFeAsO introduced the ferropnictides as a major new class of superconducting compounds with critical temperatures second only to cuprates. The presence of magnetic iron makes ferropnictides radically different from cuprates. Antiferromagnetism of the parent compounds strongly suggests that superconductivity and magnetism are closely related. However, the character of magnetic interactions and spin fluctuations in ferropnictides, in spite of vigorous efforts, has until now resisted understanding within any conventional model of magnetism. Here we show that the most puzzling features can be naturally reconciled within a rather simple effective spin model with biquadratic interactions, which is consistent with electronic structure calculations. By going beyond the Heisenberg model, this description explains numerous experimentally observed properties, including the peculiarities of the spin wave spectrum, thin domain walls, crossover from first to second order phase transition under doping in some compounds, and offers new insight in the occurrence of the nematic phase above the antiferromagnetic phase transition.Comment: 5 pages, 3 figures, revtex

Anisotropic three-dimensional magnetism in CaFe2As2

Inelastic neutron scattering measurements of the magnetic excitations in CaFe2As2 indicate that the spin wave velocity in the Fe layers is exceptionally large and similar in magnitude to the cuprates. However, the spin wave velocity perpendicular to the layers is at least half as large that in the layer, so that the magnetism is more appropriately categorized as anisotropic three-dimensional, in contrast to the two-dimensional cuprates. Exchange constants derived from band structure calculations predict spin wave velocities that are consistent with the experimental data

Magnetism and its microscopic origin in iron-based high-temperature superconductors

High-temperature superconductivity in the iron-based materials emerges from, or sometimes coexists with, their metallic or insulating parent compound states. This is surprising since these undoped states display dramatically different antiferromagnetic (AF) spin arrangements and N$\rm \acute{e}$el temperatures. Although there is general consensus that magnetic interactions are important for superconductivity, much is still unknown concerning the microscopic origin of the magnetic states. In this review, progress in this area is summarized, focusing on recent experimental and theoretical results and discussing their microscopic implications. It is concluded that the parent compounds are in a state that is more complex than implied by a simple Fermi surface nesting scenario, and a dual description including both itinerant and localized degrees of freedom is needed to properly describe these fascinating materials.Comment: 14 pages, 4 figures, Review article, accepted for publication in Nature Physic

Correction: A Seroepidemiological Study of Serogroup A Meningococcal Infection in the African Meningitis Belt.

[This corrects the article DOI: 10.1371/journal.pone.0147928.]

Ultrafast transient generation of spin-densitywave order in the normal state of BaFe2As2 driven by coherent lattice vibrations

The interplay among charge, spin and lattice degrees of freedom in solids gives rise to intriguing macroscopic quantum phenomena such as colossal magnetoresistance, multiferroicity and high-temperature superconductivity. Strong coupling or competition between various orders in these systems presents the key to manipulate their functional properties by means of external perturbations such as electric and magnetic fields or pressure. Ultrashort and intense optical pulses have emerged as an interesting tool to investigate elementary dynamics and control material properties by melting an existing order. Here, we employ few-cycle multi-terahertz pulses to resonantly probe the evolution of the spin-density-wave (SDW) gap of the pnictide compound BaFe2As2 following excitation with a femtosecond optical pulse. When starting in the low-temperature ground state, optical excitation results in a melting of the SDW order, followed by ultrafast recovery. In contrast, the SDW gap is induced when we excite the normal state above the transition temperature. Very surprisingly, the transient ordering quasi-adiabatically follows a coherent lattice oscillation at a frequency as high as 5.5 THz. Our results attest to a pronounced spin-phonon coupling in pnictides that supports rapid development of a macroscopic order on small vibrational displacement even without breaking the symmetry of the crystal

Identification by PCR of Non-typhoidal Salmonella enterica Serovars Associated with Invasive Infections among Febrile Patients in Mali

The genus Salmonella has more than 2500 serological variants (serovars), such as Salmonella enterica serovar Typhi and Salmonella Paratyphi A and B, that cause, respectively, typhoid and paratyphoid fevers (enteric fevers), and a large number of non-typhoidal Salmonella (NTS) serovars that cause gastroenteritis in healthy hosts. In young infants, the elderly and immunocompromised hosts, NTS can cause severe, fatal invasive disease. Multiple studies of pediatric patients in sub-Saharan Africa have documented the important role of NTS, in particular Salmonella Typhimurium and Salmonella Enteritidis (and to a lesser degree Salmonella Dublin), as invasive bacterial pathogens. Salmonella spp. are isolated from blood and identified by standard microbiological techniques and the serovar is ascertained by agglutination with commercial antisera. PCR-based typing techniques are becoming increasingly popular in developing countries, in part because high quality typing sera are difficult to obtain and expensive and H serotyping is technically difficult. We have developed a series of polymerase chain reactions (PCRs) to identify Salmonella Typhimurium and variants, Salmonella Enteritidis and Salmonella Dublin. We successfully identified 327 Salmonella isolates using our multiplex PCR. We also designed primers to detect Salmonella Stanleyville, a serovar found in West Africa. Another PCR generally differentiated diphasic Salmonella Typhimurium and monophasic Salmonella Typhimurium variant strains from other closely related strains. The PCRs described here will enable more laboratories in developing countries to serotype NTS that have been isolated from blood

Molecular dynamics simulation of humic substances

© 2014, Orsi. Humic substances (HS) are complex mixtures of natural organic material which are found almost everywhere in the environment, and particularly in soils, sediments, and natural water. HS play key roles in many processes of paramount importance, such as plant growth, carbon storage, and the fate of contaminants in the environment. While most of the research on HS has been traditionally carried out by conventional experimental approaches, over the past 20 years complementary investigations have emerged from the application of computer modeling and simulation techniques. This paper reviews the literature regarding computational studies of HS, with a specific focus on molecular dynamics simulations. Significant achievements, outstanding issues, and future prospects are summarized and discussed