Hyperbolic outer billiards : a first example

We present the first example of a hyperbolic outer billiard. More precisely we construct a one parameter family of examples which in some sense correspond to the Bunimovich billiards.Comment: 11 pages, 8 figures, to appear in Nonlinearit

Influence of carbon and nitrogen on electronic structure and hyperfine interactions in fcc iron-based alloys

Carbon and nitrogen austenites, modeled by Fe8N and Fe8C superstructures are studied by full-potential LAPW method. Structure parameters, electronic and magnetic properties as well as hyperfine interaction parameters are obtained. Calculations prove that Fe-C austenite can be successfully modeled by ordered Fe8C superstructure. The results show that chemical Fe-C bond in Fe8C has higher covalent part than in Fe8N. Detailed analysis of electric field gradient formation for both systems is performed. The calculation of electric field gradient allow us to carry out a good interpretation of Moessbauer spectra for Fe-C and Fe-N systems.Comment: 8 pages, 3 figures, IOP-style LaTeX, submitted to J. Phys. Condens. Matte

Urine Spot Samples Can Be Used to Estimate 24-Hour Urinary Sodium Excretion in Children.

The gold standard to assess salt intake is 24-h urine collections. Use of a urine spot sample can be a simpler alternative, especially when the goal is to assess sodium intake at the population level. Several equations to estimate 24-h urinary sodium excretion from urine spot samples have been tested in adults, but not in children. The objective of this study was to assess the ability of several equations and urine spot samples to estimate 24-h urinary sodium excretion in children. A cross-sectional study of children between 6 and 16 y of age was conducted. Each child collected one 24-h urine sample and 3 timed urine spot samples, i.e., evening (last void before going to bed), overnight (first void in the morning), and morning (second void in the morning). Eight equations (i.e., Kawasaki, Tanaka, Remer, Mage, Brown with and without potassium, Toft, and Meng) were used to estimate 24-h urinary sodium excretion. The estimates from the different spot samples and equations were compared with the measured excretion through the use of several statistics. Among the 101 children recruited, 86 had a complete 24-h urine collection and were included in the analysis (mean age: 10.5 y). The mean measured 24-h urinary sodium excretion was 2.5 g (range: 0.8-6.4 g). The different spot samples and equations provided highly heterogeneous estimates of the 24-h urinary sodium excretion. The overnight spot samples with the Tanaka and Brown equations provided the most accurate estimates (mean bias: -0.20 to -0.12 g; correlation: 0.48-0.53; precision: 69.7-76.5%; sensitivity: 76.9-81.6%; specificity: 66.7%; and misclassification: 23.0-27.7%). The other equations, irrespective of the timing of the spot, provided less accurate estimates. Urine spot samples, with selected equations, might provide accurate estimates of the 24-h sodium excretion in children at a population level. At an individual level, they could be used to identify children with high sodium excretion. This study was registered at clinicaltrials.gov as NCT02900261

Biodistribution et toxicité des nanocapsules chargées en 188Re après injection intratumorale par convection enhanced delivery chez la souris

Objectifs Déterminer la faisabilité, l’intérêt et la toxicité hématologique de l’administration intratumorale par convection enhanced delivery (CED) de nanocapsules chargées en 188Re (NCL-188Re). Matériels et méthodes L’étude de biodistribution des NCL-188Re vs perrhénate (188ReO4−) a été réalisée sur des souris nude (n = 30). Les animaux ont été séparés en 2 groupes : injection intratumorale de 188ReO4− pour le premier groupe (n = 15, 3 MBq) et de NCL-188Re pour le second groupe (n = 15, 3 MBq). Les animaux ont été sacrifiés à 1 h (n = 10), 24 h (n = 10) et 72 h (n = 10) après l’injection, les organes prélevés et comptés. La toxicité hématologique des NCL-188Re a été évaluée par prises de sang de 50 μL (sinus rétro-orbitaire) réalisées à j2, j7, j14 et j21 après traitement par NaCl (n = 4), NCL-188Re (3 MBq, n = 4), NCL-188Re (6 MBq, n = 4) et NCL-188Re (12 MBq, n = 4). Résultats La vectorisation par NCL a permis de limiter l’élimination urinaire du 188Re puisque dès 24 h post-IV 0,1 ± 0,1 % de la dose injectée (%D.I.) vs 81,9 ± 7,5 % D.I. sont retrouvés dans les urines pour les formes NCL188Re-SSS et 188ReO4-, respectivement, (p = 0,016). Celle-ci permet également de retrouver une activité significativement supérieure dans la tumeur à tous les temps de l’étude. L’administration unique de NCL-188Re a induit une toxicité modérée pour les activités injectées les plus élevées (12 MBq) se manifestant principalement par une thrombopénie transitoire de nadir j14–j18. Il n’a pas été observé de toxicité au niveau des autres lignées cellulaires pour les activités administrées de 3 et 6 MBq. Conclusions Les résultats obtenus montrent la faisabilité de l’injection intratumorale par CED et l’intérêt de la vectorisation du 188Re par les NCL. Les premiers signes de toxicité hématologiques sont en faveur du fractionnement des doses administrées et d’un meilleur ciblage par fonctionnalisation des NCL aux oestrogènes pour permettre une meilleure rétention tumorale

Contact complete integrability

Complete integrability in a symplectic setting means the existence of a Lagrangian foliation leaf-wise preserved by the dynamics. In the paper we describe complete integrability in a contact set-up as a more subtle structure: a flag of two foliations, Legendrian and co-Legendrian, and a holonomy-invariant transverse measure of the former in the latter. This turns out to be equivalent to the existence of a canonical $\R\ltimes \R^{n-1}$ structure on the leaves of the co-Legendrian foliation. Further, the above structure implies the existence of $n$ contact fields preserving a special contact 1-form, thus providing the geometric framework and establishing equivalence with previously known definitions of contact integrability. We also show that contact completely integrable systems are solvable in quadratures. We present an example of contact complete integrability: the billiard system inside an ellipsoid in pseudo-Euclidean space, restricted to the space of oriented null geodesics. We describe a surprising acceleration mechanism for closed light-like billiard trajectories

Attending school after treatment for a brain tumor: Experiences of children and key figures

Reintegration into school is a milestone for childhood brain tumor survivors, as well as for their parents, teachers, and healthcare providers. We explored their experiences following the school re-entry by conducting semi-structured interviews. Thematic analysis resulted in four main themes: "school performance," "psychosocial well-being," "support and approach," and "communication and collaboration." Children were pleased to return to school despite confrontation with adverse outcomes. Parents, teachers, and healthcare providers identified current and future concerns and challenges, as well as opportunities for academic and personal development. Their experiences highlight the importance of coordinated and systematic follow-up in close collaboration with healthcare providers

Transient Shear Wave Propagation in a Viscoelastic Gel Cylinder: Comparison of Theory to MRI-Based Measurements

ABSTRACT Shear strain patterns in a cylindrical gelatin sample under transient angular acceleration were measured by tagged magnetic resonance imaging (MRI). Measured strain fields were compared to theoretical strain fields obtained by finite element (FE) simulation. Agreement between theory and experiment is very good. The current results support the utility of the experimental approach for tasks such as measurement of shear waves in brain tissue during angular acceleration of the skull. The results also show that a simple viscoelastic model is suitable to describe rapid shear deformation of a gel biomaterial

Diagnostic bactériologique rapide de Bacteridium anthracis par immunofluorescence

Michel Claude, Poussot A., Chabassol Claude, Foata D., Poulet P. Diagnostic bactériologique rapide de Bacteridium anthracis par immunofluorescence. In: Bulletin de l'Académie Vétérinaire de France tome 126 n°8, 1973. pp. 333-342

Vertical distribution and diel patterns of zooplankton abundance and biomass at Conch Reef, Florida Keys (USA)

Zooplankton play an important role in the trophic dynamics of coral reef ecosystems. Detailed vertical and temporal distribution and biomass of zooplankton were evaluated at four heights off the bottom and at six times throughout the diel cycle over a coral reef in the Florida Keys (USA). Zooplankton abundance averaged 4396 ± 1949 SD individuals m−3, but temporal and spatial distributions varied for individual zooplankton taxa by time of day and by height off the bottom. Copepods comprised 93–96% of the abundance in the samples. Taxon-based zooplankton CHN values paired with abundance data were used to estimate biomass. Average daily biomass ranged from 3.1 to 21.4 mg C m−3 and differed by both height off the bottom and by time of day. While copepods were the numerically dominant organisms, their contribution to biomass was only 35% of the total zooplankton biomass. Our findings provide important support for the new emerging paradigm of how zooplankton are distributed over reefs