Microtomography-based Inter-Granular Network for the simulation of radionuclide diffusion and sorption in a granitic rock

Field investigation studies, conducted in the context of safety analyses of deep geological repositories for nuclear waste, have pointed out that in fractured crystalline rocks sorbing radionuclides can diffuse surprisingly long distances deep into the intact rock matrix; i.e. much longer distances than those predicted by reactive transport models based on a homogeneous description of the properties of the rock matrix. Here, we focus on cesium diffusion and use detailed micro characterisation data, based on micro computed tomography, along with a grain-scale Inter-Granular Network model, to offer a plausible explanation for the anomalously long cesium penetration profiles observed in these in-situ experiments. The sparse distribution of chemically reactive grains (i.e. grains belonging to sorbing mineral phases) is shown to have a strong control on the diffusive patterns of sorbing radionuclides. The computed penetration profiles of cesium agree well with an analytical model based on two parallel diffusive pathways. This agreement, along with visual inspection of the spatial distribution of cesium concentration, indicates that for sorbing radionuclides the medium indeed behaves as a composite system, with most of the mass being retained close to the injection boundary and a non-negligible part diffusing faster along preferential diffusive pathways.Peer reviewe

Insights on Glucocorticoid Receptor Activity Modulation through the Binding of Rigid Steroids

Background: The glucocorticoid receptor (GR) is a transcription factor that regulates gene expression in a ligand-dependent fashion. This modular protein is one of the major pharmacological targets due to its involvement in both cause and treatment of many human diseases. Intense efforts have been made to get information about the molecular basis of GR activity. Methodology/Principal Findings: Here, the behavior of four GR-ligand complexes with different glucocorticoid and antiglucocorticoid properties were evaluated. The ability of GR-ligand complexes to oligomerize in vivo was analyzed by performing the novel Number and Brightness assay. Results showed that most of GR molecules form homodimers inside the nucleus upon ligand binding. Additionally, in vitro GR-DNA binding analyses suggest that ligand structure modulates GRDNA interaction dynamics rather than the receptor's ability to bind DNA. On the other hand, by coimmunoprecipitation studies we evaluated the in vivo interaction between the transcriptional intermediary factor 2 (TIF2) coactivator and different GR-ligand complexes. No correlation was found between GR intranuclear distribution, cofactor recruitment and the homodimerization process. Finally, Molecular determinants that support the observed experimental GR LBD-ligand/TIF2 interaction were found by Molecular Dynamics simulation. Conclusions/Significance: The data presented here sustain the idea that in vivo GR homodimerization inside the nucleus can be achieved in a DNA-independent fashion, without ruling out a dependent pathway as well. Moreover, since at least one GR-ligand complex is able to induce homodimer formation while preventing TIF2 coactivator interaction, results suggest that these two events might be independent from each other. Finally, 21-hydroxy-6,19-epoxyprogesterone arises as a selective glucocorticoid with potential pharmacological interest. Taking into account that GR homodimerization and cofactor recruitment are considered essential steps in the receptor activation pathway, results presented here contribute to understand how specific ligands influence GR behavior. © 2010 Presman et al.Fil:Presman, D.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Alvarez, L.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Levi, V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Martí, M.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Veleiro, A.S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Burton, G. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Pecci, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Calibration of the CMS Drift Tube Chambers and Measurement of the Drift Velocity with Cosmic Rays

Peer reviewe

Aligning the CMS Muon Chambers with the Muon Alignment System during an Extended Cosmic Ray Run

Peer reviewe

Precise mapping of the magnetic field in the CMS barrel yoke using cosmic rays

This is the Pre-print version of the Article. The official published version can be accessed from the link below - Copyright @ 2010 IOPThe CMS detector is designed around a large 4 T superconducting solenoid, enclosed in a 12 000-tonne steel return yoke. A detailed map of the magnetic field is required for the accurate simulation and reconstruction of physics events in the CMS detector, not only in the inner tracking region inside the solenoid but also in the large and complex structure of the steel yoke, which is instrumented with muon chambers. Using a large sample of cosmic muon events collected by CMS in 2008, the field in the steel of the barrel yoke has been determined with a precision of 3 to 8% depending on the location.This work is supported by FMSR (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF (Cyprus); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA)

Educación cooperativa : experiencias escolares significativas

Fil: Ferreyra, Horacio Ademar. Universidad Católica de Córdoba. Facultad de Educación; Argentin

Educación cooperativa: experiencias escolares significativas

Fil: Ferreyra, Horacio Ademar. Universidad Católica de Córdoba. Facultad de Educación; Argentin

Tracking and Characterization of Spinal Cord-Injured Patients by Means of RGB-D Sensors

In physical rehabilitation, motion capture solutions are well-known but not as widespread as they could be. The main limit to their diffusion is not related to cost or usability but to the fact that the data generated when tracking a person must be elaborated according to the specific context and aim. This paper proposes a solution including customized motion capture and data elaboration with the aim of supporting medical personnel in the assessment of spinal cord-injured (SCI) patients using a wheelchair. The configuration of the full-body motion capturing system is based on an asymmetric 3 Microsoft Kinect v2 sensor layout that provides a path of up to 6 m, which is required to properly track the wheelchair. Data elaboration is focused on the automatic recognition of the pushing cycles and on plotting any kinematic parameter that may be interesting in the assessment. Five movements have been considered to evaluate the wheelchair propulsion: the humeral elevation, the horizontal abduction of the humerus, the humeral rotation, the elbow flexion and the trunk extension along the sagittal plane. More than 60 volunteers with a spinal cord injury were enrolled for testing the solution. To evaluate the reliability of the data computed with SCI APPlication (APP) for the pushing cycle analysis, the patients were subdivided in four groups according to the level of the spinal cord injury (i.e., high paraplegia, low paraplegia, C7 tetraplegia and C6 tetraplegia). For each group, the average value and the standard deviation were computed and a comparison with similar acquisitions performed with a high-end solution is shown. The measurements computed by the SCI-APP show a good reliability for analyzing the movements of SCI patients’ propulsion wheelchair

Micro-continuum simulation of Ra-226 migration in fractured crystalline rocks: Application of High PerformanceComputing to evaluate effects of intrinsic system heterogeneity at the micrometer scale

Deep geological disposal facilities (GDF) for high-level nuclear waste are based on multi-barrier concepts, combining an engineered barrier system with a suitable repository host rock. The migration of radionuclides from a GDF into the geo-/biosphere occurs mainlyvia the water pathway, after the waste comes into contact with groundwater, subsequently to failure of the waste canisters. In crystalline rocks, radionuclide migration is controlled by advection along fractures and diffusion into the rock matrix, and affected by various retention mechanisms such as sorption, precipitation/dissolution of discrete phases, as well as entrapment in or solid solution formation with other solids. For the post closure safety assessment of a GDF, fundamental insights into the processes governing radionuclide migration from molecular level up to the macro-scale are required, including an understanding of effects introduced by process couplings and system heterogeneity. In-situ and laboratory investigations provided evidence of the highly heterogeneous nature of the matrix of crystalline rocks with respect to microstructure and distribution of available mineral surfaces. This heterogeneity was suggested as explanation for anomalous (radio)tracer penetration profiles observed in experiments at the ONKALO underground research facility in Finland and the Äspö Hard Rock Laboratory in Sweden, and to explain discrepancies between the results of continuum-scale simulations and observations. Here, we used a synthetically generated fracture-matrix system to analyse the effects of the intrinsic grain-scale mineralogical heterogeneity of the rock matrix on processes affecting radionuclide migration, applying a micro-continuum reactive transport model. Specifically, the retention of Ra-226 due to the solid solution formation with barite (BaSO4) was addressed, which is deemed an important retention mechanism for Ra-226 and used as a solubility constraint in some safety assessments for spent nuclear fuel disposal. Due to the high computational demands, these simulations were performed on the supercomputer JUQUEEN at the Jülich Supercomputing Centre, using the massively parallel reactive transport code PFLOTRAN. The results of these simulations contribute to a refined understanding of the effects of theintrinsic heterogeneity of the rock matrix on processes controlling radionuclide migration in fractured crystalline media. Moreover, they may serve as a starting point for the development of approaches to represent system heterogeneity on multiple scales and for upscaling strategies for larger-scale reactive transport models, thus providing a more realistic view on the evolution of a repository system