OECD Review of Migrant Education - Country Report for Ireland

Immigration is a relatively new phenomenon in Ireland. Between 8 and 10% of students in Irish schools have an immigrant background representing many countries, cultures and languages. Their education outcomes are, on average, similar to their Irish-born peers. Irish schools experienced a rapid increase in the inflow of immigrant students only in recent years, and the main focus of migrant education is first-generation immigrants. Currently about 10% of students in primary schools and about 8% of students in post-primary schools have immigrant backgrounds. Unlike most other OECD countries, first-generation immigrant students in Ireland, on average, achieve education outcomes similar to their Irish-born peers, possibly because the socio-economic backgrounds of these students are similar to or higher than those of their Irish-born peers.

Cardiac rotation and relaxation after anterolateral myocardial infarction.

BACKGROUND: Both systolic and diastolic dysfunction have been observed in patients with anterolateral myocardial infarction. Diastolic dysfunction is related to disturbances in relaxation and diastolic filling. OBJECTIVE: To analyse cardiac rotation, regional shortening and diastolic relaxation in patients with anterolateral infarction. METHODS: Cardiac rotation and relaxation in controls and patients with chronic anterolateral infarction were assessed by myocardial tagging. Myocardial tagging is based on magnetic resonance imaging and allows us to label specific myocardial regions for imaging cardiac motion (rotation, translation and radial displacement). A rectangular grid was placed on the myocardium (basal, equatorial and apical short-axis plane) of each of 18 patients with chronic anterolateral infarction and 13 controls. Cardiac rotation, change in area and shortening of circumference were determined in each case. RESULTS: The left ventricle in controls performs a systolic wringing motion with a clockwise rotation at the base and a counterclockwise rotation at the apex when viewed from the apex. During relaxation a rotational motion in the opposite direction (namely untwisting) can be observed. In patients with anterolateral infarction, there is less systolic rotation at the apex and diastolic untwisting is delayed and prolonged in comparison with controls. In the presence of a left ventricular aneurysm (n = 4) apical rotation is completely lost. There is less shortening of circumference in infarcted and remote regions. CONCLUSIONS: The wringing motion of the myocardium might be an important mechanism involved in maintaining normal cardiac function with minimal expenditure of energy. This mechanism no longer operates in patients with left ventricular aneurysms and operates significantly less than normal in those with anterolateral hypokinaesia. Diastolic untwisting is significantly delayed and prolonged in patients with anterolateral infarction, which could explain the occurrence of diastolic dysfunction in these patients.

Diverse population dynamics of three Anopheles species belonging to the Triannulatus Complex (Diptera: Culicidae)

The Triannulatus Complex of Anopheles (Nyssorhynchus) consists of at least three sibling species, namely Anopheles triannulatus s.s., Anopheles halophylus and a third undescribed member herein referred to as An. triannulatus "C". Sympatric anophelines belonging to species complexes, even though closely related, may exploit different environments such as larval habitats. In this paper we hypothesize that rainfall and seasonal flooding would distinctly influence the availability of larval habitats and consequently the seasonal population dynamics of sympatric members of the Triannulatus Complex. A reflection of this is distinct seasonal biting frequencies exhibited by three members of the Triannulatus Complex at a site in Central Brazil. Population dynamics seem to be influenced by the water level in the local rivers, although biting frequency of all three species was negatively influenced by rainfall. An. triannulatus s.s. was more abundant following the end of the rainy season, but notably 30 to 60 days after flooding. On the other hand, An. halophylus and An. triannulatus C peaked during the middle of the dry season, when water impoundments have no inflow, are somewhat reduced in size and the water becomes brackish. Differences in population dynamics were greater between An. triannulatus s.s. and An. halophylus and An. triannulatus C than between An. halophylus and An. triannulatus C. This might reflect differences in larval habitat exploitation and therefore spatial segregation among these members of the complex.

The Management of Patients on Oral Anticoagulation Undergoing Coronary Stent Implantation: A Survey among Interventional Cardiologists from Eight European Countries.

Purpose:  To evaluate the current management, and adherence to recommendations, of patients on oral anticoagulation (OAC) undergoing coronary stent implantation (PCI-S). Methods:  By means of a contact person who had been previously identified in 8 European countries, a questionnaire was electronically forwarded between April and July 2010 to the national institutions where PCI-S is performed. Results:  A total of  202 questionnaires (median response rate: 50%, range 33-78%) was received. The prevalence of OAC patients among those undergoing PCI-S is mostly reported 5-10% (97%). The peri-procedural pharmacological management mostly encompasses: preprocedural OAC interruption and bridging with low-molecular-weight heparin (59%), intraprocedural administration of an unfractionated heparin bolus (81%), and use of glycoprotein IIb/IIIa inhibitors on an individual basis (79%). The radial approach is reported as the preferred option (58%), as well as the implantation of bare metal stents (76%). Triple therapy (warfarin, aspirin, clopidogrel) is the most frequently prescribed (80%), generally for 1 month after bare metal stent (77%) and for at least 12 months after drug-eluting stent (60%). Throughout triple therapy, the International Normalized Ratio is mostly targeted to the lower end of the therapeutic range (77%), and gastric protection is routinely prescribed (69%), mostly by giving proton-pump inhibitors (70%). Conclusions:  Among the 202 interventional cardiologists from the 8 European countries interviewed, the management of patients on OAC undergoing PCI-S appears variable and only partially adherent to currently available recommendations. (J Interven Cardiol 2012;25:163-169).

Mise en oeuvre de protocoles spatiaux pour analyser la modulation de processus cognitifs en fonction de la dimension émotionnelle chez le rongeur

Résumé : Emotion et cognition sont deux termes généralement employés pour désigner des processus psychiques de nature opposée. C'est ainsi que les sciences cognitives se sont longtemps efforcées d'écarter la composante «chaude »des processus «froids »qu'elles visaient, si ce n'est pour montrer l'effet dévastateur de la première sur les seconds. Pourtant, les processus cognitifs (de collecte, maintien et utilisation d'information) et émotioAnels (d'activation subjective, physiologique et comportementale face à ce qui est attractif ou aversif) sont indissociables. Par l'approche neuro-éthologique, à l'interface entre le substrat biologique et les manifestations comportementales, nous nous sommes intéressés à une fonction cognitive essentielle, la fonction mnésique, classiquement exprimée chez le rongeur par l'orientation spatiale. Au niveau du substrat, McDonald et White (1993) ont montré la dissociation de trois systèmes de mémoire, avec les rôles de l'hippocampe, du néostriatum et de l'amygdale dans l'encodage des informations respectivement épisodiques, procédurales et émotionnelles. Nous nous sommes penchés sur l'interaction entre ces systèmes en fonction de la dimension émotionnelle par l'éclairage du comportement. L'état émotionnel de l'animal dépend de plusieurs facteurs, que nous avons tenté de contrôler indirectement en comparant leurs effets sur l'acquisition, dans diverses conditions, de la tâche de Morris (qui nécessite la localisation dans un bassin de la position d'une plate-forme submergée), ainsi que sur le style d'exploration de diverses arènes, ouvertes ou fermées, plus ou moins structurées par la présence de tunnels en plexiglas transparent. Nous avons d'abord exploré le rôle d'un composant du système adrénergique dans le rapport à la difficulté et au stress, à l'aide de souris knock-out pour le récepteur à la noradrénaline a-1 B dans un protocole avec 1 ou 4 points de départ dans un bassin partitionné. Ensuite, nous nous sommes penchés, chez le rat, sur les effets de renforcement intermittent dans différentes conditions expérimentales. Dans ces conditions, nous avons également tenté d'analyser en quoi la situation du but dans un paysage donné pouvait interférer avec les effets de certaines formes de stress. Finalement, nous avons interrogé les conséquences de perturbations passées, y compris le renforcement partiel, sur l'organisation des déplacements sur sol sec. Nos résultats montrent la nécessité, pour les souris cont~ô/es dont l'orientation repose sur l'hippocampe, de pouvoir varier les trajectoires, ce qui favoriserait la constitution d'une carte cognitive. Les souris a->B KO s'avèrent plus sensibles au stress et capables de bénéficier de la condition de route qui permet des réponses simples et automatisées, sous-tendues par l'activité du striatum. Chez les rats en bassin 100% renforcé, l'orientation apparaît basée sur l'hippocampe, relayée par le striatum pour le développement d'approches systématiques et rapides, avec réorientation efficace en nouvelle position par réactivation dépendant de l'hippocampe. A 50% de renforcement, on observe un effet du type de déroulement des sessions, transitoirement atténué par la motivation Lorsque les essais s'enchaînent sans pause intrasession, les latences diminuent régulièrement, ce qui suggère une prise en charge possible par des routines S-R dépendant du striatum. L'organisation des mouvements exploratoires apparaît dépendante du niveau d'insécurité, avec différents profils intermédiaires entre la différentiation maximale et la thigmotaxie, qui peuvent être mis en relation avec différents niveaux d'efficacité de l'hippocampe. Ainsi, notre travail encourage à la prise en compte de la dimension émotionnelle comme modulatrice du traitement d'information, tant en phase d'exploration de l'environnement que d'exploitation des connaissances spatiales. Abstract : Emotion and cognition are terms widely used to refer to opposite mental processes. Hence, cognitive science research has for a long time pushed "hot" components away from "cool" targeted processes, except for assessing devastating effects of the former upon the latter. However, cognitive processes (of information collection, preservation, and utilization) and emotional processes (of subjective, physiological, and behavioral activation roue to attraction or aversion) are inseparable. At the crossing between biological substrate and behavioral expression, we studied a chief cognitive function, memory, classically shown in animals through spatial orientation. At the substrate level, McDonald et White (1993) have shown a dissociation between three memory systems, with the hippocampus, neostriatum, and amygdala, encoding respectively episodic, habit, and emotional information. Through the behavior of laboratory rodents, we targeted the interaction between those systems and the emotional axis. The emotional state of an animal depends on different factors, that we tried to check in a roundabout way by the comparison of their effects on acquisition, in a variety of conditions, of the Morris task (in which the location of a hidden platform in a pool is required), as well as on the exploration profile in different apparatus, open-field and closed mazes, more or less organized by clear Plexiglas tunnels. We first tracked the role, under more or less difficult and stressful conditions, of an adrenergic component, with knock-out mice for the a-1 B receptor in a partitioned water maze with 1 or 4 start positions. With rats, we looked for the consequences of partial reinforcement in the water maze in different experimental conditions. In those conditions, we further analyzed how the situation of the goal in the landscape could interfere with the effect of a given stress. At last, we conducted experiments on solid ground, in an open-field and in radial mazes, in order to analyze the organization of spatial behavior following an aversive life event, such as partial reinforcement training in the water maze. Our results emphasize the reliance of normal mice to be able to vary approach trajectories. One of our leading hypotheses is that such strategies are hippocampus-dependent and are best developed for of a "cognitive map like" representation. Alpha-1 B KO mice appear more sensitive to stress and able to take advantage of the route condition allowing simple and automated responses, most likely striatum based. With rats in 100% reinforced water maze, the orientation strategy is predominantly hippocampus dependent (as illustrated by the impairment induced by lesions of this structure) and becomes progressively striatum dependent for the development of systematic and fast successful approaches. Training towards a new platform position requires a hippocampus based strategy. With a 50% reinforcement rate, we found a clear impairment related to intersession disruption, an effect transitorily minimized by motivation enhancement (cold water). When trials are given without intrasession interruption, latencies consistently diminish, suggesting a possibility for striatum dependent stimulus-response routine to occur. The organization of exploratory movements is shown to depend on the level of subjective security, with different intermediary profiles between maximum differentiation and thigmotaxy, which can be considered in parallel with different efficiency levels of the hippocampus dependent strategies. Thus, our work fosters the consideration of emotion as a cognitive treatment modulator, during spatial exploration as well as spatial learning. It leads to a model in which the predominance of hippocampus based exploration is challenged by training conditions of various nature.

Free-breathing 3 T magnetic resonance t(2)-mapping of the heart.

OBJECTIVES: This study sought to establish an accurate and reproducible T(2)-mapping cardiac magnetic resonance (CMR) methodology at 3 T and to evaluate it in healthy volunteers and patients with myocardial infarct. BACKGROUND: Myocardial edema affects the T(2) relaxation time on CMR. Therefore, T(2)-mapping has been established to characterize edema at 1.5 T. A 3 T implementation designed for longitudinal studies and aimed at guiding and monitoring therapy remains to be implemented, thoroughly characterized, and evaluated in vivo. METHODS: A free-breathing navigator-gated radial CMR pulse sequence with an adiabatic T(2) preparation module and an empirical fitting equation for T(2) quantification was optimized using numerical simulations and was validated at 3 T in a phantom study. Its reproducibility for myocardial T(2) quantification was then ascertained in healthy volunteers and improved using an external reference phantom with known T(2). In a small cohort of patients with established myocardial infarction, the local T(2) value and extent of the edematous region were determined and compared with conventional T(2)-weighted CMR and x-ray coronary angiography, where available. RESULTS: The numerical simulations and phantom study demonstrated that the empirical fitting equation is significantly more accurate for T(2) quantification than that for the more conventional exponential decay. The volunteer study consistently demonstrated a reproducibility error as low as 2 ± 1% using the external reference phantom and an average myocardial T(2) of 38.5 ± 4.5 ms. Intraobserver and interobserver variability in the volunteers were -0.04 ± 0.89 ms (p = 0.86) and -0.23 ± 0.91 ms (p = 0.87), respectively. In the infarction patients, the T(2) in edema was 62.4 ± 9.2 ms and was consistent with the x-ray angiographic findings. Simultaneously, the extent of the edematous region by T(2)-mapping correlated well with that from the T(2)-weighted images (r = 0.91). CONCLUSIONS: The new, well-characterized 3 T methodology enables robust and accurate cardiac T(2)-mapping at 3 T with high spatial resolution, while the addition of a reference phantom improves reproducibility. This technique may be well suited for longitudinal studies in patients with suspected or established heart disease.

Perspectives of auto-correcting lens distortions in mosaic-based underwater navigation

When unmanned underwater vehicles (UUVs) perform missions near the ocean floor, optical sensors can be used to improve local navigation. Video mosaics allow to efficiently process the images acquired by the vehicle, and also to obtain position estimates. We discuss in this paper the role of lens distortions in this context, proving that degenerate mosaics have their origin not only in the selected motion model or in registration errors, but also in the cumulative effect of radial distortion residuals. Additionally, we present results on the accuracy of different feature-based approaches for self-correction of lens distortions that may guide the choice of appropriate techniques for correcting distortions

Brachial artery peak velocity variation to predict fluid responsiveness in mechanically ventilated patients

INTRODUCTION Although several parameters have been proposed to predict the hemodynamic response to fluid expansion in critically ill patients, most of them are invasive or require the use of special monitoring devices. The aim of this study is to determine whether noninvasive evaluation of respiratory variation of brachial artery peak velocity flow measured using Doppler ultrasound could predict fluid responsiveness in mechanically ventilated patients. METHODS We conducted a prospective clinical research in a 17-bed multidisciplinary ICU and included 38 mechanically ventilated patients for whom fluid administration was planned due to the presence of acute circulatory failure. Volume expansion (VE) was performed with 500 mL of a synthetic colloid. Patients were classified as responders if stroke volume index (SVi) increased >or= 15% after VE. The respiratory variation in Vpeakbrach (DeltaVpeakbrach) was calculated as the difference between maximum and minimum values of Vpeakbrach over a single respiratory cycle, divided by the mean of the two values and expressed as a percentage. Radial arterial pressure variation (DeltaPPrad) and stroke volume variation measured using the FloTrac/Vigileo system (DeltaSVVigileo), were also calculated. RESULTS VE increased SVi by >or= 15% in 19 patients (responders). At baseline, DeltaVpeakbrach, DeltaPPrad and DeltaSVVigileo were significantly higher in responder than nonresponder patients [14 vs 8%; 18 vs. 5%; 13 vs 8%; P < 0.0001, respectively). A DeltaVpeakbrach value >10% predicted fluid responsiveness with a sensitivity of 74% and a specificity of 95%. A DeltaPPrad value >10% and a DeltaSVVigileo >11% predicted volume responsiveness with a sensitivity of 95% and 79%, and a specificity of 95% and 89%, respectively. CONCLUSIONS Respiratory variations in brachial artery peak velocity could be a feasible tool for the noninvasive assessment of fluid responsiveness in patients with mechanical ventilatory support and acute circulatory failure. TRIAL REGISTRATION ClinicalTrials.gov ID: NCT00890071.

Environnement et capacités cognitives chez le rat : compétition entre les facteurs qui influencent les stratégies spatiales

RESUME Ce travail se propose de discuter des résultats comportementaux observés chez des rats obtenus dans trois paradigmes expérimentaux différents : le bassin de Morris (Morris Water Maze, Morris, 1984) ; la table à trous (Homing Board, Schenk, 1989) et le labyrinthe radial (Radial Arm Maze, Olton et Samuelson, 1976). Les deux premières tâches sont spatiales et permettent un apprentissage de place en environnements contrôlés, et la troisième est une tâche comportementale qui différencie deux habiletés particulières, celle d'élimination (basée sur la mémoire de travail) et celle de sélection (basée sur la mémoire de référence). La discussion des résultats porte sur les stratégies de navigation utilisées par les animaux pour résoudre les tâches et plus précisément sur les facteurs qui peuvent influencer le choix de ces stratégies. Le facteur environnemental (environnement contrôlé) et le facteur cognitif (vieillissement) représentent les variables étudiées ici. C'est ainsi que certaines hypothèses communément acceptées ont été malmenées par nos résultats. Or si l'espace est habituellement supposé homogène (toutes les positions spatiales présentent le même degré de difficulté lors d'un apprentissage en champ ouvert), ce travail établit qu'une position associée -sans contiguïté - à l'un des trois indices visuels situés dans la périphérie de l'environnement est plus difficile à apprendre qu'une position située entre deux des trois indices. Deuxièmement, alors qu'il est admis que l'apprentissage d'une place dans un environnement riche requiert le même type d'information. dans la bassin de Morris (tâche nagée) que sur la table à trous (tâche marchée), nous avons montré que la discrimination spatiale en bassin ne peut être assurée par les trois indices visuels périphériques et nécessite la présence d'au moins un élément supplémentaire. Enfin, l'étude du vieillissement a souvent montré que l'âge réduit les capacités cognitives nécessaires à la navigation spatiale, conduisant à un déficit général des performances d'un animal sénescent, alors que dans notre travail, nous avons trouvé les animaux âgés plus performants et plus efficaces que les adultes dans une tâche particulière de collecte de nourriture. Ces expériences s'inscrivent dans une étude générale qui met à l'épreuve le modèle théorique proposé pax Schenk et Jacobs (2003), selon lequel l'encodage de la carte cognitive (Tolman, 1948 ; O'Keefe et Nadel, 1978) se ferait dans l'hippocampe par l'activité de deux modules complémentaires :d'une part le CA3 - Gyrus Denté pour le traitement d'une trame spatiale basée sur des éléments directionnels et Jou distribués en gradient (bearing map) et d'autre part le CAl - Subiculum pour le traitement des représentations locales basées sur les positions relatives des éléments fixes de l'environnement (sketch map). SUMMARY This work proposes to talk about behavioural results observed in three different experimental paradigms with rats: the Morris Water Maze (Morris, 1984); the Homing Board (Schenk, 1989) and the Radial Arm Maze (Olton and Samuelson, 1976). The two first tasks are spatial ones and allow place learning in controlled environments. The third one is a behavioural task which contrasts two particular skills, the elimination (based on working memory) and the selection one (based on reference memory). The topic of the discussion will be the navigation strategies used by animals to solve the different tasks, and more precisely the factors which can bias this strategies' choice. The environmental (controlled) and the cognitive (aging) factors are the variables studied here. Thus, some hypotheses usually accepted were manhandled by our results. Indeed, if space is habitually homogenously considered (all spatial positions present the same degree of difficulty in an open field learning), this work establishes that an associated position -without being adjacent - to one of the three visual cues localised in the environmental periphery is more difficult to learn than a configurationnel position (situated between two of the three cues). Secondly, if it is received that place learning in a rich environment requires the same information in the Morris water maze (swimming task) that on the Homing board (walking task), we showed that spatial discrimination in the water maze can't be provided by the three peripheral cue cards and needs the presence of a supplementary cue. At last, aging studies often showed that oldness decreases cognitive skills in spatial navigation, leading to a general deficit in performances. But, in our work, we found that senescent rats were more efficient than adult ones in a special food collecting task. These experiments come within the scope of a general study which tests the theoretical model proposed by Jacobs and Schenk (2003), according to which the cognitive map's encoding (Tolman, 1948, O'Keefe and Nadel, 1978) should take place in the hippocampus by two complementary modules, first the DG-CA3 should encode directional and/or gradients references (the bearing map), and secondly the Subiculum-CAl should process locale elements (the sketch map).

Self-Navigation with Compressed Sensing for 2D Translational Motion Correction in Free-Breathing Coronary MRI: A Feasibility Study.

PURPOSE: Respiratory motion correction remains a challenge in coronary magnetic resonance imaging (MRI) and current techniques, such as navigator gating, suffer from sub-optimal scan efficiency and ease-of-use. To overcome these limitations, an image-based self-navigation technique is proposed that uses "sub-images" and compressed sensing (CS) to obtain translational motion correction in 2D. The method was preliminarily implemented as a 2D technique and tested for feasibility for targeted coronary imaging. METHODS: During a 2D segmented radial k-space data acquisition, heavily undersampled sub-images were reconstructed from the readouts collected during each cardiac cycle. These sub-images may then be used for respiratory self-navigation. Alternatively, a CS reconstruction may be used to create these sub-images, so as to partially compensate for the heavy undersampling. Both approaches were quantitatively assessed using simulations and in vivo studies, and the resulting self-navigation strategies were then compared to conventional navigator gating. RESULTS: Sub-images reconstructed using CS showed a lower artifact level than sub-images reconstructed without CS. As a result, the final image quality was significantly better when using CS-assisted self-navigation as opposed to the non-CS approach. Moreover, while both self-navigation techniques led to a 69% scan time reduction (as compared to navigator gating), there was no significant difference in image quality between the CS-assisted self-navigation technique and conventional navigator gating, despite the significant decrease in scan time. CONCLUSIONS: CS-assisted self-navigation using 2D translational motion correction demonstrated feasibility of producing coronary MRA data with image quality comparable to that obtained with conventional navigator gating, and does so without the use of additional acquisitions or motion modeling, while still allowing for 100% scan efficiency and an improved ease-of-use. In conclusion, compressed sensing may become a critical adjunct for 2D translational motion correction in free-breathing cardiac imaging with high spatial resolution. An expansion to modern 3D approaches is now warranted.

Confirmation of Anopheles (Anopheles) calderoni Wilkerson, 1991 (Diptera: Culicidae) in Colombia and Ecuador through molecular and morphological correlation with topotypic material

The morphologically similar taxa Anopheles calderoni, Anopheles punctimacula, Anopheles malefactor and Anopheles guarao are commonly misidentified. Isofamilies collected in Valle de Cauca, Colombia, showed morphological characters most similar to An. calderoni, a species which has never previously been reported in Colombia. Although discontinuity of the postsubcostal pale spots on the costa (C) and first radial (R1) wing veins is purportedly diagnostic for An. calderoni, the degree of overlap of the distal postsubcostal spot on C and R1 were variable in Colombian specimens (0.003-0.024). In addition, in 98.2% of larvae, seta 1-X was located off the saddle and seta 3-C had 4-7 branches in 86.7% of specimens examined. Correlation of DNA sequences of the second internal transcribed spacer and mtDNA cytochrome c oxidase subunit I gene (COI) barcodes (658 bp of the COI gene) generated from Colombian progeny material and wild-caught mosquitoes from Ecuador with those from the Peruvian type series of An. calderoni confirmed new country records. DNA barcodes generated for the closely related taxa, An. malefactor and An. punctimacula are also presented for the first time. Examination of museum specimens at the University of the Valle, Colombia, revealed the presence of An. calderoni in inland localities across Colombia and at elevations up to 1113 m.

Enhanced diastolic reflections on arterial pressure pulse during exercise recovery.

During recovery from a maximal or submaximal aerobic exercise, augmentation of central (aortic) systolic pressure by reflected pressure waves is blunted in healthy humans. However, the extent to which reflected pressure waves modify the central pulse in diastole in these conditions remains unknown. We evaluated systolic and diastolic central reflected waves in 11 endurance-trained athletes on recovery from a maximal running test on a treadmill (treadmill-max) and a 4000 m run in field conditions. On both occasions in each subject, the radial pulse was recorded with applanation tonometry in the resting preexercise state and then 5, 15, 25, 35, and 45 min after exercise termination. From the central waveform, as reconstructed by application of a generalized transfer function, we computed a systolic (AIx) and a diastolic index (AId) of pressure augmentation by reflections. At 5 min, both indices were below preexercise. At further time-points, AIx remained low, while AId progressively increased, to overshoot above preexercise at 45 min. The same behavior was observed with both exercise types. Beyond the first few minutes of recovery following either maximal or submaximal aerobic exercise, reflected waves selectively augment the central pressure pulse in diastole, at least in endurance-trained athletes.

Recherche translationnelle: de l'animal modèle de schizophrénie à la forme humaine de difficulté cognitive. Evaluation des performances de navigation spatiale et des stratégies utilisées

Un protocole de tests sur labyrinthe radial permettant d'évaluer la navigation spatial chez l'homme a été réalisé. Ces tests sur labyrinthe radial sont basés sur le protocole utilisé sur l'animal modèle de schizophrénie dans le CNP (Centre de neuroscience psychiatrique) de Lausanne. Les recherches actuelles du CNP ont montré un déficit dans les capacités d'orientation spatiale de ces animaux [13]. Ainsi notre méthodologie consistera à tester des sujets humains dans des tâches de labyrinthe afin d'étudier de la manière la plus équivalente les différents déficits observés dans la pathologie humaine et dans le rat modèle. Cette démarche est à la base d'une approche translationnelle qui combine recherches cliniques et expérimentales. Le travail expérimental a été mené sur deux dispositifs analogues. a) «radial au doigt», ensemble de petits canaux qui peuvent être explorés par le doigt, yeux ouverts ou fermés et dans lesquels des textures différentes tapissent chaque bras. b) «radial sur écran tactile», deux labyrinthes qui comparent deux types d'indice locale, couleurs différentes ou patrons noir-blanc. Dans les deux dispositifs a été prévu une série de tests permettant d'évaluer la mémorisation des indices utilisés en les supprimant temporairement où en les mettant en contradiction. La première perturbation a pour but de tester l'importance du référentiel locale par une rotation de 90° du labyrinthe. La permutation des bras lors d'un dernier essai permet d'induire une situation ou les informations ont été soit correctes spatialement mais incorrectes localement (texture) soit inversement. Ces perturbations des informations sensorielles qui sont fournies au sujet, permettent d'observer les systèmes de repérage et leur poids relatif dans la construction d'un système de référence durant la navigation spatiale. Les résultats du labyrinthe radial au doigt montrent que dans les conditions utilisant les informations visuelles les participants sont sensiblement plus performants. Il est apparu que les informations visuelles prédominent sur les informations proprioceptives et tactiles. Ainsi dans la condition intégrant informations visuospatiales, proprioceptives et tactiles, les sujets basent plus fortement leur navigation spatiale sur les indices visuelles soit locale soit spatiale. Dans cette condition une différence significative de stratégie entre hommes et femmes est apparue. Les hommes se basent majoritairement sur des indices spatiaux tandis que les femmes préfèrent les indices locaux. En présence d'informations tactiles et proprioceptives mais en absence de la vision, les participants utilisent les références spatiale et locale complémentairement sans avoir un système prédominant. Alors que si uniquement les informations proprioceptives sont présentes, les sujets utilisent un système de référence spatiale (globale). Le labyrinthe radial sur écran tactile indique une différence de système de référence selon l'indice local employé. Les couleurs, étant des forts indices locaux, vont favoriser un système de référence local. Au contraire les patrons noirs-blancs sont des indices visiblement très complexes et difficiles à mémoriser qui vont pousser les sujets à utiliser une stratégie de référence spatiale.

Automated quantitative histology reveals vascular morphodynamics during Arabidopsis hypocotyl secondary growth.

Among various advantages, their small size makes model organisms preferred subjects of investigation. Yet, even in model systems detailed analysis of numerous developmental processes at cellular level is severely hampered by their scale. For instance, secondary growth of Arabidopsis hypocotyls creates a radial pattern of highly specialized tissues that comprises several thousand cells starting from a few dozen. This dynamic process is difficult to follow because of its scale and because it can only be investigated invasively, precluding comprehensive understanding of the cell proliferation, differentiation, and patterning events involved. To overcome such limitation, we established an automated quantitative histology approach. We acquired hypocotyl cross-sections from tiled high-resolution images and extracted their information content using custom high-throughput image processing and segmentation. Coupled with automated cell type recognition through machine learning, we could establish a cellular resolution atlas that reveals vascular morphodynamics during secondary growth, for example equidistant phloem pole formation. DOI: http://dx.doi.org/10.7554/eLife.01567.001.

Long time behaviour of diffusing particles in constrained geometries; application to chromatin motion

Inspired by experiments that use single-particle tracking to measure the regions of confinement of selected chromosomal regions within cell nuclei, we have developed an analytical approach that takes into account various possible positions and shapes of the confinement regions. We show, in particular, that confinement of a particle into a subregion that is entirely enclosed within a spherical volume can lead to a higher limit of the mean radial square displacement value than the one associated with a particle that can explore the entire spherical volume. Finally, we apply the theory to analyse the motion of extrachromosomal chromatin rings within nuclei of living yeast.