Predictors of vitamin D status and its association with parathyroid hormone in young New Zealand children.

BACKGROUND: Despite increased awareness of the adverse health effects of low vitamin D status, few studies have evaluated 25-hydroxyvitamin D [25(OH)D] status in young children. OBJECTIVES: We aimed to assess vitamin D status on the basis of 25(OH)D and its relation with parathyroid hormone (PTH) and to identify possible predictors of 25(OH)D status in young children living in a country with minimal vitamin D fortification. DESIGN: Serum 25(OH)D and PTH concentrations were measured in a cross-sectional sample of children aged 12-22 mo [n = 193 for 25(OH)D, n = 144 for PTH] living in Dunedin, New Zealand (latitude: 45 degrees S). Anthropometric, dietary, and sociodemographic data were collected. RESULTS: The majority of children sampled in the summer (94%; 47 of 50) had 25(OH)D >50 nmol/L; however, nearly 80% of children sampled in the winter (43 of 55) had serum concentrations 60-65 nmol/L, a plateau in PTH was evident. CONCLUSIONS: Seasonal variation in 25(OH)D concentration implies that postsummer vitamin D stores were insufficient to maintain status >50 nmol/L year-round. Examination of the predictors of 25(OH)D in our model shows few modifiable risk factors, and thus effective dietary strategies may be required if future research determines that children with 25(OH)D concentrations <50 nmol/L are at significant health risk. This trial was registered at www.actr.org.au as ACTRN12605000487617

Simulations of the solar orbiter spacecraft interactions with the solar wind: effects on RPW and SWA/EAS measurements

International audienceWe present numerical simulations of the future Solar Orbiter spacecraft/plasma interactions performed with the Spacecraft Plasma Interaction System (SPIS) software. This spacecraft, to be launched in October 2018, is dedicated to the Sun observation with in-situ and remote sensing instruments, brought as close as 0.28 A.U. from our star. In this hot and dense environment, the entire satellite will be submitted to high radiations and temperatures (up to 10 Solar constants). Material responses to environment constraints (heat, U.V. flux, photoemission, secondary electron emission under electron impact – SEEE – or under proton impact - SEEP) might bias the scientific instrument measurements. Our interest is focused on two instruments: the Radio and Plasma Waves (RPW) and the Electron Analyzer System (EAS)

Etude et simulations des phénomènes d'interactions satellite/plasma et de leurs impacts sur les mesures de plasmas basses énergies

Les satellites scientifiques sont immergés dans divers environnements spatiaux, entourés par des plasmas qu'ils sont supposés analyser, en utilisant des instruments de types détecteurs de particules. La présence de ces structures dans le plasma conduit à une variété d'interactions satellite/plasma complexes et inter-corrélées. L'environnement spatial influence la structure du satellite qui modifie son environnement. Les instruments embarqués mesurent un environnement perturbé et il est difficile de distinguer le signal naturel des mesures biaisées. Le but est d'étudier et d'améliorer la compréhension des interactions satellite/plasma, au moyen de simulations numériques effectuées avec le logiciel SPIS pour les basses énergies (<100 eV) puisque ces particules sont les plus affectées par les perturbations. L'objectif est de comprendre les mesures de plasmas sur des cas réalistes, en établissant une méthodologie de simulation de ces problématiques. Je simule les interactions ayant lieu entre les missions Solar Probe Plus, Solar Orbiter, Cluster dans leurs environnements respectifs et les mesures associées. L'analyse des résultats obtenus et leurs comparaisons à des données réelles permettent de comprendre les différents cas de figure et de valider la méthodologie développée au cours de cette thèse.Scientific satellites immersed in various space environments are surrounded by plasmas which they are supposed to analyze, using instruments such as particle detectors. The presence of these structures within the plasma leads to a variety of complex and inter-correlated spacecraft/plasma interactions. The space plasma modifies the satellite which in return disturbs its close environment. On-board instruments measure a perturbed plasma and it is difficult to distinguish the natural signal from biased measurements. The objective of this thesis is to study and improve the understanding of the spacecraft/plasma interactions, through numerical simulations performed with the SPIS software, on the low energy domain (<100 eV), as those particles are the most perturbed. The aim is to understand plasma measurements on realistic cases, by establishing a methodology of simulating those issues. I simulate interactions between the Solar Probe Plus, Solar Orbiter, Cluster missions and their respective environments, including the associated measurements. The analysis of the obtained results allows the understanding of the various cases and the validation of the methodology developed during this work

The effect of postexercise carbohydrate and protein ingestion on bone metabolism

Purpose To investigate the effect of feeding carbohydrate and protein (CHO+PRO), immediately or 2 h after an exhaustive run, on the bone turnover response in endurance runners. Methods 10 men (age 28±5 y, height 1.74±0.05 m, body mass 69.7±6.3 kg) performed treadmill running at 75%VO2max, until exhaustion, on three occasions. Blood was collected before and immediately, 1, 2, 3, 4 and 24 h post-exercise, for measurement of β-CTX, P1NP, PTH, PO4, ACa and Ca2+. This was a randomised, counterbalanced, placebo-controlled, single-blinded, cross-over study. The three trials were; i) placebo (PLA), PLA solution was ingested immediately and 2 h post-exercise, ii) immediate feeding (IF), CHO+PRO (1.5 g.kgBM-1 dextrose and 0.5 g.kgBM-1 whey) were ingested immediately post-exercise and PLA 2 h post-exercise, and iii) delayed feeding (DF), PLA was ingested immediately post-exercise and CHO+PRO solution 2 h post-exercise. Data were analysed using repeated measures ANOVA and post-hoc Tukey’s HSD. Results At 1 and 2 h post-exercise, β-CTX concentrations were lower in the IF trial than the DF and PLA trials (P≤0.001). At 3 h post-exercise, β-CTX concentrations were higher in the PLA trial than the IF (P≤0.001) and DF trials (P=0.026). At 4 h post-exercise, β-CTX concentrations were lower in the DF trial than the IF (P=0.003) and PLA trials (P≤0.001). At 4 h post-exercise, P1NP was higher in the IF trial than in DF (P=0.026) and PLA trials (P=0.001). At 3 h post-exercise, PTH was higher in the IF trial than the DF trial (P≤0.001). Conclusions Following exhaustive running, immediate ingestion of CHO+PRO may be beneficial, as it decreases bone resorption marker concentrations and increases bone formation marker concentrations; creating a more positive bone turnover balance

Dynamic complex scene analysis with the fractal embedding method

We present a new image sequence analysis method for automatic and real-time extraction of transitory and complex motions in natural scenes. We show how to extract these motions as multidimensional point clusters obtained from the temporal embedding of grey level variations, in five successive steps: embedding, fractal indexing, point chaining, cluster identification and data extraction. We develop the two main algorithms: fractal space filling indexing and chaining in order to access directly to the relevant information. To illustrate our method, we present an automatic system for early smoke source detection through the processing of landscape images by extracting fugitive and various movements within a small spot of pixels affected by the smoke. We show how to modify the embedding technique used to obtain the data points coordinates to produce many other applications for the fractal embedding method, for example the recognition of complex moving or varying shapes objects.Nous présentons une nouvelle méthode d'analyse de séquences d'images adaptée à l'extraction automatique en temps réel de mouvements localisés dans des scènes naturelles. Nous montrons comment extraire ces mouvements sous la forme de voisinages de points formés dans un espace de très grande dimension par le plongement temporel des variations de niveaux de gris des pixels d'une même enveloppe. Nous présentons tout d'abord notre méthode d'extraction rapide des voisinages dans cet espace multidimensionnel. Ses étapes principales sont l'indexation et le chaînage des points : l'indexation des points se fait selon une courbe fractale qui remplit l'espace, et le chaînage des points indexés permet un accès immédiat aux points voisins. Nous validons ensuite la méthode dans le cas du plongement temporel d'enveloppes de pixels rendus dynamiques par la présence de fumée. L'application est un détecteur des feux de forêts capable de faire la distinction entre des enveloppes causées par une source de fumée ou par tout autre phénomène dynamique pouvant apparaître localement dans un paysage. On exploite les propriétés caractéristiques des mouvements fugitifs et diversifiés qui sont causés par les bouffées de fumée, même à l'intérieur de petites enveloppes de pixels. Nous généralisons ensuite les perspectives d'utilisation de la méthode du plongement fractal en envisageant d'autres types d'applications par l'extraction de caractéristiques autres que des mouvements

Activation dimension of EEG :a cue tool with a real time algorithm

This article presents a fast, robust and practical method for direct quantification of brain activity computed on scalp electroencephalogram (EEG) data. This new indicator called Activation Dimension (DA) is based on the well-known correlation dimension D2. The results of DA calculation from several EEG corroborate our claim in the study of activation of EEG by cognitive task, desactivation of EEG during sleep wake cycles and during anesthesia.Cet article présente une nouvelle méthode de quantification directe de l’activité cérébrale enregistrée par électroencéphalographie (EEG), qui présente l’avantage d’être à la fois rapide et bien adaptée à la dynamique de l’EEG. Nous introduisons la notion de dimension d’activation dont le calcul commence comme celui de la dimension de corrélation D2. Les résultats de calcul obtenus pour différents états d’activation pendant une tache cognitive, un état de sommeil ou une anesthésie montrent que la dimension d’activation, que nous allons introduire, est alors un bon estimateur de l’activité cérébrale

Early Forest Fire Detection Using Radio-Acoustic Sounding System

Automated early fire detection systems have recently received a significant amount of attention due to their importance in protecting the global environment. Some emergent technologies such as ground-based, satellite-based remote sensing and distributed sensor networks systems have been used to detect forest fires in the early stages. In this study, a radio-acoustic sounding system with fine space and time resolution capabilities for continuous monitoring and early detection of forest fires is proposed. Simulations show that remote thermal mapping of a particular forest region by the proposed system could be a potential solution to the problem of early detection of forest fires