Anterior and posterior commissures in agenesis of the corpus callosum: alternative pathways for attention processes?

Developmental absence (agenesis) of the corpus callosum (AgCC) is a congenital brain malformation resulting from disruption of corpus callosum formation, a structure that is crucial for the transfer and integration of information, including attention processes, across the brain. This study aimed to investigate previously proposed candidates for alternative inter-hemispheric pathways in AgCC by examining (1) white matter volume and microstructure of the anterior and posterior commissures in children with AgCC compared to typically developing controls (TDC), and (2) in children with AgCC, examine the associations of white matter volume and microstructure of the anterior and posterior commissures and any remaining corpus callosum with attention processes. Participants were 21 children with AgCC (13 complete, 8 partial) recruited from The Royal Children's Hospital, Melbourne, and 30 TDC aged 8–17 years. T1-and diffusion-weighted MR sequences were used to calculate volume and microstructural parameters. Neuropsychological testing assessed attention processes. We found the anterior commissure was significantly larger in volume in children with AgCC than TDC (p = .027), with reduced mean FA (p = .001) associated with increased mean RD (p < .001). In children with AgCC, we found microstructural properties of the anterior commissure associated with attentional processes, specifically, mean FA of the anterior commissure was associated with better divided attention (p = .03), and the association between alerting attention and mean AD and RD was found to be moderated by age (p = .027, p = .008) and the degree of corpus callosum agenesis (p = .025, p = .016). Furthermore, in partial AgCC, larger posterior commissure volume was associated with better orienting attention (p = .035). In conclusion, we provide evidence that the volume and microstructure of the anterior commissure are altered in children with AgCC, and this neuroplastic response might have an influence on attention processes

Lyons (James Anthony), The Cosmic Christ in Origen and Teilhard de Chardin, 1982

Guénot C. Lyons (James Anthony), The Cosmic Christ in Origen and Teilhard de Chardin, 1982. In: Revue des Sciences Religieuses, tome 57, fascicule 1, 1983. pp. 79-80

Lyons (James Anthony), The Cosmic Christ in Origen and Teilhard de Chardin, 1982

Guénot C. Lyons (James Anthony), The Cosmic Christ in Origen and Teilhard de Chardin, 1982. In: Revue des Sciences Religieuses, tome 57, fascicule 1, 1983. pp. 79-80

Multidisciplinary approach for assessing the atmospheric impact of launchers

Exhausts from rockets influence the atmospheric chemistry and the atmospheric radiative transfer. Assessing these effects requires a multidisciplinary approach. It ranges from combustion calculations in the rocket engines to plume simulations on different scales. The plume is first analysed with computational fluid dynamic models and engineering methods. Then a diffusion model is applied and lastly a chemical transport model is used for simulations on a global scale. This approach is currently being implemented in the Atmospheric Impact of Launchers project, which is funded by ESA as part of its CleanSpace Initiative. Therefore, the focus of this study lies on rockets launching from Kourou, which are Ariane 5, Vega and Soyuz

SIMULATION OF RIA TRANSIENTS ON MOX FUEL RODS WITH ALCYONE FUEL PERFORMANCE CODE

International audienceAs regards Reactivity-Initiated Accidents (RIAs), the ALCYONE multidimensional fuel performance code co-developed by CEA, EDF and Framatome within the PLEIADES software environment is intended to predictively simulate the response of a fuel rod by taking account of mechanisms in a way that models the physics as closely as possible, encompassing all possible stages of the transient (PCMI and post-DNB phases) as well as various fuel/cladding material types and irradiation conditions of interest. Validated for PWR-UO2 fuels, it is now being adapted to simulate the behaviour of Zircaloy-4-based claddings shrouding MOX fuel pellets. ALCYONE V1.4 RIA-related features and modelling are first presented. The constitutive model for the oxide fuel includes cracking in tension, thermal creep and grain-boundary cracking. The modelling of grain-boundary cracking-induced fission gas release (the dominant release mechanism in RIAs) and swelling are discussed in this paper. Simulations of RIA transients performed on MOX fuel rods from the French CABRI REP-Na programme in flowing sodium coolant conditions are then compared to relevant experimental results. This paper shows to what extent ALCYONE-starting from base irradiation conditions it itself computes-is currently ready to simulate and analyse further tests on MOX fuel to be performed under prototypical PWR conditions within the CABRI International Programme. The homogeneous modelling gives satisfactory results. An alternative and heterogeneous approach may be a complementary path towards a more local description of the MOX fuel behaviour under RIA conditions: if both heterogeneous and homogeneous approaches will give the same information and results at the macroscopic level, the heterogeneous one will enable to understand, via numerical simulations, what happens at lower (meso-and microscopic) scales

SIMULATION OF RIA TRANSIENTS ON UO2 -M5® FUEL RODS WITH ALCYONE V1.4 FUEL PERFORMANCE CODE

International audienceThe ALCYONE multidimensional fuel performance code co-developed by the CEA, EDF and AREVA NP within the PLEIADES software environment models the behavior of fuel rods during irradiation in commercial Pressurized Water Reactors (PWRs), power ramps in experimental reactors or accidental conditions such as Loss Of Coolant Accidents (LOCAs) or Reactivity-Initiated Accidents (RIAs). As regards the latter case of transient in particular, ALCYONE is intended to predictively simulate the response of a fuel rod by taking account of mechanisms as close to physics as possible, encompassing all possible stages of the transient as well as various fuel/cladding material types and irradiation conditions of interest. On the way to complying with these objectives, its development and validation shall include tests on PWR-UO 2 fuel rods with advanced claddings such as M5® under " low pressure-low temperature " or " high pressure-high temperature " water coolant conditions. This paper first presents the ALCYONE V1.4 RIA-related features and modeling. It especially focuses on recent developments dedicated on the one hand to non steady water heat and mass transport and on the other hand to the modeling of grain boundary cracking-induced fission gas release and swelling. This paper then compares some simulations of RIA transients performed on UO 2-M5® fuel rods in flowing sodium or stagnant water coolant conditions to the relevant experimental results gained from tests performed in either the French CABRI or the Japanese NSRR nuclear transient reactor facilities. It shows in particular to what extent ALCYONE – starting from base irradiation conditions it itself computes – is currently able to handle both the first stage of the transient, namely the Pellet Cladding Mechanical Interaction (PCMI) phase, and the second stage of the transient, should the boiling crisis occur. Areas of improvement are finally discussed with a view to simulating and analyzing further tests to be performed under prototypical PWR conditions within the CABRI International Program. M5® is a trademark or a registered trademark of AREVA NP in the USA or other countries

Temporal plus epilepsy is a major determinant of temporal lobe surgery failures.

Reasons for failed temporal lobe epilepsy surgery remain unclear. Temporal plus epilepsy, characterized by a primary temporal lobe epileptogenic zone extending to neighboured regions, might account for a yet unknown proportion of these failures. In this study all patients from two epilepsy surgery programmes who fulfilled the following criteria were included: (i) operated from an anterior temporal lobectomy or disconnection between January 1990 and December 2001; (ii) magnetic resonance imaging normal or showing signs of hippocampal sclerosis; and (iii) postoperative follow-up ≥ 24 months for seizure-free patients. Patients were classified as suffering from unilateral temporal lobe epilepsy, bitemporal epilepsy or temporal plus epilepsy based on available presurgical data. Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom over time. Predictors of seizure recurrence were investigated using Cox proportional hazards model. Of 168 patients included, 108 (63.7%) underwent stereoelectroencephalography, 131 (78%) had hippocampal sclerosis, 149 suffered from unilateral temporal lobe epilepsy (88.7%), one from bitemporal epilepsy (0.6%) and 18 (10.7%) from temporal plus epilepsy. The probability of Engel class I outcome at 10 years of follow-up was 67.3% (95% CI: 63.4-71.2) for the entire cohort, 74.5% (95% CI: 70.6-78.4) for unilateral temporal lobe epilepsy, and 14.8% (95% CI: 5.9-23.7) for temporal plus epilepsy. Multivariate analyses demonstrated four predictors of seizure relapse: temporal plus epilepsy (P &lt; 0.001), postoperative hippocampal remnant (P = 0.001), past history of traumatic or infectious brain insult (P = 0.022), and secondary generalized tonic-clonic seizures (P = 0.023). Risk of temporal lobe surgery failure was 5.06 (95% CI: 2.36-10.382) greater in patients with temporal plus epilepsy than in those with unilateral temporal lobe epilepsy. Temporal plus epilepsy represents a hitherto unrecognized prominent cause of temporal lobe surgery failures. In patients with temporal plus epilepsy, anterior temporal lobectomy appears very unlikely to control seizures and should not be advised. Whether larger resection of temporal plus epileptogenic zones offers greater chance of seizure freedom remains to be investigated

Conceptual Designs Of Complementary Safety Devices For Astrid: From Selection Method To Selected Options

International audience– To comply with the GEN IV objectives set for it, the 600 MWe Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID) promises enhanced safety. The ability to shut the reactor down in any condition is one of the most important safety aspects. At the end of ASTRID preconceptual design phase (end of 2012), the need for additional safety devices that would complement ASTRID low void fraction (CFV) design core natural behavior in case of unprotected loss of flow (ULOF) and loss of heat sink (ULOHS) transients emerged from the transient studies in order to meet temperature criteria on coolant, core and primary circuit structures. The process from the selection method, on the basis of ASTRID functional specifications and safety requirements, to the selected options/designs, on the basis of itemization of these specifications/requirements and value engineering, of ASTRID Complementary Safety Devices (DCS) is presented. In this paper, only DCS dedicated to core melting Prevention (DCS-P) that would passively shutdown the reactor, i.e. whose actuation would be triggered by the sole physical effects induced by the transient, are dealt with regardless of whether they would depend on ASTRID first two distinct and independent fast-acting reactor shutdown systems (RBC and RBD) or not. Several concepts of such DCS-P were considered among which SEPIA (abbreviation for SEntinal for Passive Insertion of Antireactivity) concept of absorber subassembly specifically designed by CEA, (DCS-P)-H concept of hydraulically suspended absorber rod subassembly and (DCS-P)-RBD_Curie concept based on the exploitation of the Curie point of the RBD electromagnetic delatch system; they are listed and discussed with regard to whether and how they could effectively match each type of ULOF and ULOHS transient (some concepts that were abandoned are discussed as well). Concepts which are the most promising in ASTRID framework, resulting from the best way their combination could deal with all considered transients, are finally described; these will be further investigated and developed in the near future