The impact of early and late literacy on the functional connectivity of vision and

Introduction: Learning to read leads to functional and structural changes in the cortical regions related to vision and language. The visual word-form area (VWFA) is though to play a key role in the interaction between these two systems (Dehaene et al. 2015). For instance, the VWFA is activated not only from bottom-up during reading but also in a top-down manner during speech listening without visual stimulation (Dehaene et al. 2010). The objective of this study was twofolded: how literacy acquisition affects four intrinsic functional connectivity networks related to vision and language (a dorsal language [DLN], a bilateral auditory [AN], a low-level [LLVN] and a high-level visual [HLVN] networks); and to explore the role of the VWFA as an interface between high-level vision and language functions. Methods: Independent component analysis (ICA) was applied to functional magnetic resonance imaging data from 40 adult participants with variable levels of literacy (illiterate, late literate and early literate). The four functional connectivity networks were compared across groups using dual-regression (Filippini et al. 2009). In addition, we directly explored the functional connectivity between the VWFA and each of the studied networks. Finally, the strengh of connectivity between the VWFA and each network was compared across groups and correlated with individual reading fluency scores. Results: ICA produced 40 networks, and spatial crosscorrelation was used to identify the four networks of interest. Literacy was positively correlated with increased connectivity within the four networks. A major difference separating early literate from illiterate and late literate subjects was found. The connectivity between the VWFA and the DLN increased with literacy. Conversely, the strength of connectivity between the VWFA and the HLVN correlated negatively with literacy. Finally, , the HLVN-VWFA connectivity was negatively correlated with reading scores while the connectivity between the DLN-VWFA was positively correlated with reading scores. Discussion:Literacy has a strong influence on the visual and language functional networks. Literacy modifies the VWFA connectivity, by making it functionally closer to the language system, and more distinct from other associative visual areas that do not contribute to the reading process. The current results suggest that early acquisition of literacy plays a critical role for the tuning of the functional brain architecture. References: -Dehaene S et al. Nat Rev Neurosci.(2015)16:234 244 -Dehaene S et al. Science.(2010)330:1359–1364 -Filippini N et al. PNAS.(2009)106, 7209–7214Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Structure determination in 55-atom Li–Na and Na–K nanoalloys

Producción CientíficaThe structure of 55-atom Li–Na and Na–K nanoalloys is determined through combined empirical potential (EP) and density functional theory (DFT) calculations. The potential energy surface generated by the EP model is extensively sampled by using the basin hopping technique, and a wide diversity of structural motifs is reoptimized at the DFT level. A composition comparison technique is applied at the DFT level in order to make a final refinement of the global minimum structures. For dilute concentrations of one of the alkali atoms, the structure of the pure metal cluster, namely, a perfect Mackay icosahedron, remains stable, with the minority component atoms entering the host cluster as substitutional impurities. At intermediate concentrations, the nanoalloys adopt instead a core-shell polyicosahedral (p-Ih) packing, where the element with smaller atomic size and larger cohesive energy segregates to the cluster core. The p-Ih structures show a marked prolate deformation, in agreement with the predictions of jelliumlike models. The electronic preference for a prolate cluster shape, which is frustrated in the 55-atom pure clusters due to the icosahedral geometrical shell closing, is therefore realized only in the 55-atom nanoalloys. An analysis of the electronic densities of states suggests that photoelectron spectroscopy would be a sufficiently sensitive technique to assess the structures of nanoalloys with fixed size and varying compositions

Iterative Automatic Segmentation in cardiac PET based on TAC correlation: preliminary results

Proceeding of: 2010 IEEE Nuclear Science Symposium, Medical Imaging Conference and 17th Room Temperature Semiconductor Detector Workshop (IEEE), Knoxville, Tennessee, USA, October 30 - November 6, 2010Conventional kinetic parameter estimation based on compartmental models requires an accurate estimation of arterial blood input function. To avoid invasive blood sampling, an image-derived input function can be obtained by manually defining a Region of Interest. Here we propose a new and simple, iterative method for automatic segmentation and input function calculation of PET cardiac studies using correlation as a distance metric between a priori information regarding the approximate shape of the final time-activity curve (TAC) and the actual TAC extracted from the image temporal series.This work was supported in part by the CENIT-AMIT Ingenio 2010, Ministerio de Ciencia e Innovación, TEC2007-64731, TEC 2008-06715-C02-1, RETIC-RECAVA, Ministerio de Sanidad y Consumo, and the ARTEMIS de la Comunidad de Madrid (S2009/DPI-1802) programsPublicad

Deep variational autoencoders for breast cancer tissue modeling and synthesis in SFDI

Extracting pathology information embedded within surface optical properties in Spatial Frequency Domain Imaging (SFDI) datasets is still a rather cumbersome nonlinear translation problem, mainly constrained by intrasample and interpatient variability, as well as dataset size. The B-variational autoencoder (B-VAE) is a rather novel dimensionality reduction technique where a tractable set of latent low-dimensional embeddings can be obtained from a given dataset. These embeddings can then be sampled to synthesize new data, providing further insight into pathology variability as well as differentiability in terms of optical properties. Its applications for data classification and breast margin delineation are also discussed.Research reported in this manuscript was funded by PhD grant FPU016/05705 (Spanish Ministry of Education, Culture and Sports), projects DTS1700055 (FUSIODERM), INNVAL 16/02 (DICUTEN), INNVAL 18/23 (DAPATOO), and TEC201676021C22R (SENSA), as well as cofunded with FEDER funds

PeneloPET simulations of the Biograph ToF clinical PET scanner

Proceedings of: 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). Valencia, Spain, 23-29 October 2011Monte Carlo simulations are widely used in positron emission tomography (PET) for optimizing detector design, acquisition protocols, as well as for developing and assessing corrections and reconstruction methods. PeneloPET is a Monte Carlo code for PET simulations which considers detector geometry, acquisition electronics and materials, and source definitions. PeneloPET is based on PENELOPE, a Monte Carlo code for the simulation of the transport in matter of electrons, positrons and photons, with energies up to 1 GeV. In this work we use PeneloPET to simulate the Biograph TruePoint (B-TP), Biograph TruePoint with TrueV (B-TPTV) and Biograph mCT PET/CT scanners. These configurations consist of three (B-TP) and four (B-TPTV and mCT) rings of 48 detector blocks. Each block comprises a 13 × 13 matrix of 4 × 4 × 20 mm3 LSO crystals. Simulations were adjusted to reproduce some experimental results from the actual scanners and validated by comparing their predictions to further experimental results. Sensitivity, spatial resolution, noise equivalent count (NEC) rate and scatter fraction (SF) were estimated. The simulations were then employed to estimate the optimum values of system parameters, such as energy and time coincidence windows and to assess the effect of system modifications (such as number of rings) on performance.This work was supported in part by Comunidad de Madrid (ARTEMIS S2009IDPI 1802), Spanish Ministry of Science and Innovation (ENTEPRASE Grant, PSE 300000 2009 5) and PRECISION grant IPT 300000 2010 3 and european regional funds and CPAN, Centro de Fisica de Particulas, Astroparticulas y Nuclear (CSD 2007 00042@Ingenio2010 12). This study has been (partially) funded by CDTI under the CENIT Programme (AMIT Project). Part of the calculations of this work was performed in the "Cluster de Calculo de Alta Capacidad para Tecnicas Fisicas "funded in part by UCM and in part by UE with European regional funds"Publicad

Performance evaluation of the GE healthcare eXplore VISTA dual-ring small-animal PET scanner

This work was supported in part by grant CA92871 from the National Institutes of Health, Bethesda, MD.Publicad

Automatic TAC extraction from dynamic cardiac PET imaging using iterative correlation from a population template

This work describes a new iterative method for extracting time-activity curves (TAC) from dynamic imaging studies using a priori information from generic models obtained from TAC templates. Analytical expressions of the TAC templates were derived from TACs obtained by manual segmentation of three 13NH3 pig studies (gold standard). An iterative method for extracting both ventricular and myocardial TACs using models of the curves obtained as an initial template was then implemented and tested. These TACs were extracted from masked and unmasked images; masking was applied to remove the lungs and surrounding non-relevant structures. The resulting TACs were then compared with TACs obtained manually; the results of kinetic analysis were also compared. Extraction of TACs for each region was sensitive to the presence of other organs (e.g., lungs) in the image. Masking the volume of interest noticeably reduces error. The proposed method yields good results in terms of TAC definition and kinetic parameter estimation, even when the initial TAC templates do not accurately match specific tracer kinetics.This work is supported by the following grants: RD07/0014/2009, Subprograma RETICS, Ministerio de Ciencia e Innovación. S2009/DPI-1802 (ARTEMIS), Comunidad de Madrid. CEN-20101014, Programa CENIT, CDTI, Ministerio de Ciencia e Innovación. European Commission, EFPIA, INNOVATIVE MEDICINE INITIATIVE (PredDICT-TB project, 115337-1)Publicad

Efficacy of different antifouling treatments for seawater cooling systems

In an industrial seawater cooling system, the effects of three different antifouling treatments, viz. sodium hypochlorite (NaClO), aliphatic amines (Mexel1432) and UV radiation, on the characteristics of the fouling formed were evaluated. For this study a portable pilot plant, as a side-stream monitoring system and seawater cooling system, was employed. The pilot plant simulated a power plant steam condenser, having four titanium tubes under different treatment patterns, where fouling progression could be monitored. The nature of the fouling obtained was chiefly inorganic, showing a clear dependence on the antifouling treatment employed. After 72 days the tubes under treatment showed a reduction in the heat transfer resistance (R) of around 70% for NaClO, 48% for aliphatic amines and 55% for UV, with respect to the untreated tube. The use of a logistic model was very useful for predicting the fouling progression and the maximum asymptotic value of the increment in the heat transfer resistance (DRmax). The apparent thermal conductivity (l) of the fouling layer showed a direct relationship with the percentage of organic matter in the collected fouling. The characteristics and mode of action of the different treatments used led to fouling with diverse physicochemical properties

Iterative 4D reconstruction of dynamic SPECT images

[Abstract] The 22nd International Congress and Exhibition, Barcelona, Spain, June 25-28, 2008The present work presents a new approach for the 4D reconstruction algorithm for dynamic SPECT in a parallel ray geometry based on B-splines including attenuation map from CT and geometry efficiency correction. In this work we make use of 4 piecewise piecewise quadratic temporal splines and a reconstruction algorithm based on the iterative maximization of Poisson likelihood. Results on a Tecnetium (99mTc-Teboroxime) canine study are shownPublicad

An investigation of silicon carbide-water nanofluid for heat transfer applications

Thermal conductivity and mechanical effects of silicon carbide nanoparticles uniformly dispersed in water were investigated. Mean size of SiC particles was 170 nm with a polydispersity of 30% as determined from small-angle x-ray scattering and dynamic light scattering techniques. Room temperature viscosity of the nanofluids ranged from 2 to 3 cP for nominal nanoparticle loadings 4 – 7 vol %. On a normalized basis with water, viscosity of the nanofluids did not significantly change with the test temperature up to 85 °C. Optical microscopy of diluted nanofluid showed no agglomeration of the nanoparticles. Thermal conductivity of the fluid was measured as a function of the nominal nanoparticle loading ranging from 1 to 7 vol %. Enhancement in thermal conductivity was approximately 28% over that of water at 7 vol % particle loadings under ambient conditions. Enhancements in thermal conductivities for the nanofluids with varying nanoparticle loadings were maintained at test temperatures up to 70 °C. Results of thermal conductivity have been rationalized based on the existing theories of heat transfer in fluids. Implications of using this nanofluid for engineering cooling applications are discussed.Universidad de Chicago Argonne LLC (EE. UU.)-DE-AC02-06CH1135