Two approaches for effective modelling of rain-rate time-series for radiocommunication system simulations

The paper presents a model which allows to synthetically generate rain rate time-series for a fixed location. Rain rate time-series are very much correlated with signal attenuation in Ka band and above and, thus, enable to realistically simulate propagation effects on Earth-satellite links. The model presented are based on Markov chains

Plate motions, Andean orogeny, and volcanism above the South Atlantic convection cell

International audienceThe geometric and kinematic evolution of the Andes provides insight onto the nature of the force balance beneath the South American plate. While the Andean load is opposed on its western edge by the force induced by subduction of the Nazca plate, its more elusive eastern counterpart, which we explore herein, requires some contribution from the mantle beneath the South Atlantic. Using a mantle flow model, we show that the Andes owe their existence to basal drag beneath South America caused by a cylindrical convection cell under the South Atlantic. We find that the observed Andean uplift requires both westward push fromactive upwelling beneath Africa andwestward drag toward the downgoing Nazca slab. These mutually-reinforcing downwellings and upwellings amount to 38% and 23% of the total driving force, respectively. Further decomposition reveals that the South Atlantic cell is most vigorous near its center, rendering the net drag force higher where the Andes also reach their highest elevation. Kinematic reconstructions suggest that the South Atlantic cell could have grown owing to the migration of the Nazca slab until ~50 Ma. We propose that from 50 Ma onwards, the cell may have ceased growing westward because (i) it had reached an optimal aspect ratio and (ii) the Nazca slab became anchored into the lower mantle. Continued westward motion of the plates, however, moved the surface expressions of spreading and convergence away from the upwelling and downwelling arms of this cell. Evidence for this scenario comes from the coeval tectonic, morphologic, and magmatic events in Africa and South America during the Tertiary

Assessment of inoculation methods for screening black alder resistance to Phytophthora ×alni

International audienceIdentification of resistance to Phytophthora ×alni could provide the basis for a management strategy against alder decline in riparian ecosystems in Europe. Our objectives were to test methods to evaluate the resistance of riparian alders to the disease, and to screen alder genotypes for resistance. P. ×alni isolates were compared for their stability in collection, aggressiveness (lesion length on stem) and sporulation capacity (sporangia). While no difference of lesion lengths was found between P. ×alni isolates, sporangia production was dependent on isolate, highlighting the need to select carefully isolates for inoculation methods dealing with zoospores suspension. Inoculation tests carried out at different periods of the year revealed a seasonal change in susceptibility to the disease, with the period from June to September being the most efficient for inoculation tests. Stem-wounded inoculations tests carried out on excised shoots were found unreliable for evaluating the level of resistance of alder genotypes to P. ×alni infection, with divergent results between two successive years or between two inoculation periods during the same year. In contrast, a method which mimics the natural conditions of infection based on flooding of rooted cuttings in artificially infected river water was found promising. Another method based on the inoculation of foliated terminal shoots with zoospore suspensions was found to be repeatable and could be used for high throughput analyses. Altogether, the results show a continuous resistance response from highly susceptible to moderately resistant genotypes. This suggests that breeding might be a useful strategy to manage alder decline caused by P. ×alni

Leaf Eh and pH: A Novel Indicator of Plant Stress. Spatial, Temporal and Genotypic Variability in Rice (Oryza sativa L.)

A wealth of knowledge has been published in the last decade on redox regulations in plants. However, these works remained largely at cellular and organelle levels. Simple indicators of oxidative stress at the plant level are still missing. We developed a method for direct measurement of leaf Eh and pH, which revealed spatial, temporal, and genotypic variations in rice. Eh (redox potential) and Eh@pH7 (redox potential corrected to pH 7) of the last fully expanded leaf decreased after sunrise. Leaf Eh was high in the youngest leaf and in the oldest leaves, and minimum for the last fully expanded leaf. Leaf pH decreased from youngest to oldest leaves. The same gradients in Eh-pH were measured for various varieties, hydric conditions, and cropping seasons. Rice varieties differed in Eh, pH, and/or Eh@pH7. Leaf Eh increases and leaf pH decreases with plant age. These patterns and dynamics in leaf Eh-pH are in accordance with the pattern and dynamics of disease infections. Leaf Eh-pH can bring new insight on redox processes at plant level and is proposed as a novel indicator of plant stress/health. It could be used by agronomists, breeders, and pathologists to accelerate the development of crop cultivation methods leading to agroecological crop protection

Progrès récents de l'Imagerie par Résonance Magnétique (IRM) chez le nouveau-né. Recent advances in newborn MRI

International audienceAbstractThe accurate morphological exploration of the brain is a major challenge in neonatology that advances in magnetic resonance imaging (MRI) can now provide. MRI is the gold standard if an hypoxic ischemic pathology is suspected in a full term neonate. In prematures, the specific role of MRI remains to be defined, secondary to US in any case. We present a state of the art of hardware and software technical developments in MRI. The increase in magnetic field strength (3 tesla) and the emergence of new MRI sequences provide access to new information. They both have positive and negative consequences on the daily clinical data acquisition use. The semiology of brain imaging in full term newborns and prematures is more extensive and complex and thereby more difficult to interpret. The segmentation of different brain structures in the newborn, even very premature, is now available. It is now possible to dissociate the cortex and basal ganglia from the cerebral white matter, to calculate the volume of anatomical structures, which improves the morphometric quantification and the understanding of the normal and abnormal brain development. MRI is a powerful tool to analyze the neonatal brain. The relevance of the diagnostic contribution requires an adaptation of the parameters of the sequences to acquire and of the image processing methods.RésuméL’exploration morphologique fine du cerveau est un enjeu majeur en néonatalogie que les avancées de l’imagerie par résonance magnétique (IRM) permettent actuellement. L’IRM est l’examen de choix devant une suspicion de pathologie anoxo-ischémique à terme. Chez le prématuré, la place précise de l’IRM reste à définir, toujours en seconde intention après l’échographie transfontanellaire (ETF). Nous dressons un panorama des évolutions techniques récentes matérielles et logicielles, en IRM. L’augmentation de l’intensité des champs magnétiques (3 teslas) et l’apparition de nouvelles séquences donnent accès à de nouvelles informations. Elles ont des conséquences positives et négatives sur l’acquisition des données en utilisation clinique quotidienne. La sémiologie de l’imagerie cérébrale du nouveau-né et du prématuré est désormais plus riche, plus complexe et donc d’interprétation plus difficile. La segmentation des différentes structures cérébrales devient accessible chez le nouveau-né, même grand prématuré. Il est aujourd’hui possible de dissocier le cortex et les noyaux gris de la substance blanche cérébrale, de calculer des volumes de structures anatomiques, ce qui améliore la quantification morphométrique et la compréhension du développement cérébral normal et pathologique. L’IRM est un outil inégalable et puissant pour l’analyse du cerveau du nouveau-né, dont la pertinence de l’apport diagnostique requiert une adaptation des paramètres des séquences à acquérir et des méthodes de traitement d’images

The tropospheric gas composition of Jupiter's north equatorial belt (NH3, PH3, CH3D, GeH4, H2O) and the Jovian D/H isotropic ratio

The gas composition of the troposphere of Jupiter in the clearest regions of the North Equatorial Belt (NEB) was derived from the Voyager 1 IRIS data. The infrared spectrum for this homogeneous cloud free region was modeled to infer altitude profiles for NH3, PH3, GeH4 and H2O. The Profiles for NH3 and PH3 were found to be depleted in the upper troposphere but otherwise in agreement with their solar values at the 1 bar level. The mole fraction for CH3D was determined to be 3.5(+1.0 or -1.3) x 10 to the minus 7th power. The GeH4 mole fraction of 7+ or -2 x 10 to the minus 10th power at the 2 to 3 bar level is a factor of 10 lower than the solar value. The H2O mole fraction is approximately 1 x 0.00001 at the 2.5 bar level and is increasing to approximately 3 x 0.00001 at 4 bars where it is a factor of 30 lower than solar. Using IRIS infrared values for the mole fractions of CH3D and CH4 a value of D/H = 3.6(+1.0 or -1.4)x 0.00001 is derived. Assuming this Jovian D/H ratio is representative of the protosolar nebula, and correcting for chemical galactic evolution, yields a value of 5.5 - 9.0 x 0.00001 for the primordial D/H ratio and an upper limit of 1.8 to 2.4 x 10 to the minus 31st power cu cm for the present day baryon density

Генетический полиморфизм клонов и их семенного потомства в архивно-клоновой плантации плюсовых деревьев сосны обыкновенной

Изучена генетическая изменчивость по 12 аллозимным локусам (10 полиморфных) архивно-клоновой плантации 23 плюсовых деревьев Pinus sylvestris L. и их семенного потомства на юго-востоке Украины. Более половины клонов имели 4–8 гетерозиготных локусов, а их семенное потомство отличалось меньшим уровнем изменчивости, чем материнские растения. Семенное потомство получено от высокой доли ауткроссинга (tm = = 95 %). Для потомства клонов характерна повышенная доля нарушений сегрегации аллелей в мегагаметофитах и высокая встречаемость существенных отклонений в распределении генотипов зародышей семян от теоретически ожидаемого согласно закону Харди Вайнберга.Досліджено генетичну мінливість за 12 алозимними локусами (10 поліморфних) архівно-клонової плантації 23 плюсових дерев Pinus sylvestris L. та їх насіннєвого потомства на південному сході України. Понад половина клонів мали 4–8 гетерозиготних локусів, а їх насіннєве потомство відрізнялося нижчим рівнем мінливості, ніж материнські рослини. Насіннєве потомство отримано від високої частки ауткросинга (tm = 95 %). Для потомства клонів характерна підвищена частка порушень сегрегації алелів у мегагаметофітах і висока частота відхилень розподілу генотипів зародків насіння від очікуваного згідно з законом Харді-Вайнберга.Genetic variation at 12 allozyme loci (10 of them being polymorphic ones) has been studied in the archive-clone plantation of 23 Pinus sylvestris plus-trees and their seed progeny in the south-east of Ukraine. More than a half of clones had 4–8 heterozygous loci, whereas their seed progeny was marked by a lower variation than maternal trees. Seed progeny was obtained at a high outcrossing rate (tm= 95 %). The clone progeny was characterized by a high percentage of abnormal allele segregation in megagametophytes. There was also a high frequency of significant deviation in distribution of seed embryo genotypes from the theoretically expected one according to the Hardy-Weinberg law

New insights (and new interrogations) in perinatal arterial ischemic stroke

With an incidence of 1/2800 to 1/5000 live-births, perinatal arterial ischemic stroke is the most frequent form of cerebral infarction in children. About 40% of the children do not have specific symptoms in the neonatal period, and are only recognized later with the emergence of motor impairment, developmental delay, specific cognitive deficiency or seizures. In the remaining 60%, children present with early symptoms, mostly recurrent focal seizures in the first 3 days of life. The diagnosis is easily confirmed by cranial ultrasounds and MRI. Early MRI has both a key role in the diagnosis, dating the injury, but also an important prognostic value to predict the motor outcome of the child. Indeed, although the infarct does not recur, the majority of children show subsequent sequels: cerebral palsy, epilepsy, cognitive or behavioural problems. Finding predictors of outcome regarding these latter concerns (and the way to prevent or alleviate them) is of major interest.The main etiological hypothesis for perinatal AIS is a cerebral embolus, originating from the placenta through the foramen ovale. Most of the established risk factors are indeed either determinants or biomarkers of vasculo-placental pathology. Injury to the cervico-cerebral arteries, giving rise to thrombus/embolus during the birthing process is also suggested. Both placento-embolic and traumatic theories are supported by a few, but well-analysed pathological or arteriographic reports. Nevertheless, their relative frequency, the implication of other mechanisms, and their repercussions to evidence-based preventive strategies remain to be determined. Moreover, the mechanism of stroke in the different groups of newborns with stroke (term vs. preterm; symptomatic neonates vs. those with a delayed presentation) is likely to be different, and there is a need for future studies to assess all populations as different entities. Neonatal supportive care remains important for all infants while there is no evidence for preventive anticoagulant use at present. In an effort to reduce neurological dysfunction, and in adjunction with ongoing physical therapy and pharmacological treatment, new rehabilitative interventions, such as constraint-induced movement therapy and mirror therapy, are increasingly being used