9,373 research outputs found

    Subjective value and decision entropy are jointly encoded by aligned gradients across the human brain

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    Recent work has considered the relationship between value and confidence in both behavioural and neural representation. Here we evaluated whether the brain organises value and confidence signals in a systematic fashion that reflects the overall desirability of options. If so, regions that respond to either increases or decreases in both value and confidence should be widespread. We strongly confirmed these predictions through a model-based fMRI analysis of a mixed gambles task that assessed subjective value (SV) and inverse decision entropy (iDE), which is related to confidence. Purported value areas more strongly signalled iDE than SV, underscoring how intertwined value and confidence are. A gradient tied to the desirability of actions transitioned from positive SV and iDE in ventromedial prefrontal cortex to negative SV and iDE in dorsal medial prefrontal cortex. This alignment of SV and iDE signals could support retrospective evaluation to guide learning and subsequent decisions

    Subjective value and decision entropy are jointly encoded by aligned gradients across the human brain

    Get PDF
    Recent work has considered the relationship between value and confidence in both behavioural and neural representation. Here we evaluated whether the brain organises value and confidence signals in a systematic fashion that reflects the overall desirability of options. If so, regions that respond to either increases or decreases in both value and confidence should be widespread. We strongly confirmed these predictions through a model-based fMRI analysis of a mixed gambles task that assessed subjective value (SV) and inverse decision entropy (iDE), which is related to confidence. Purported value areas more strongly signalled iDE than SV, underscoring how intertwined value and confidence are. A gradient tied to the desirability of actions transitioned from positive SV and iDE in ventromedial prefrontal cortex to negative SV and iDE in dorsal medial prefrontal cortex. This alignment of SV and iDE signals could support retrospective evaluation to guide learning and subsequent decisions

    Magnetic Structure of Hydrogen Induced Defects on Graphene

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    Using density functional theory (DFT), Hartree-Fock, exact diagonalization, and numerical renormalization group methods we study the electronic structure of diluted hydrogen atoms chemisorbed on graphene. A comparison between DFT and Hartree-Fock calculations allows us to identify the main characteristics of the magnetic structure of the defect. We use this information to formulate an Anderson-Hubbard model that captures the main physical ingredients of the system, while still allowing a rigorous treatment of the electronic correlations. We find that the large hydrogen-carbon hybridization puts the structure of the defect half-way between the one corresponding to an adatom weakly coupled to pristine graphene and a carbon vacancy. The impurity's magnetic moment leaks into the graphene layer where the electronic correlations on the C atoms play an important role in stabilizing the magnetic solution. Finally, we discuss the implications for the Kondo effect.Comment: 10 pages, 10 fig

    The Effect of Expertise during Simulated Flight Emergencies on the Autonomic Response and Operative Performance in Military Pilots.

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    Heart rate variability (HRV) and performance response during emergency flight maneuvers were analyzed. Two expert pilots (ages 35 and 33) and two rookie pilots (ages 25) from the Portuguese Air Force participated in this case–control report study. Participants had to complete the following emergency protocols in a flight simulator: (1) take-off engine failure, (2) flight engine failure close to the base, (3) flight engine failure far away from the base, and (4) alternator failure. The HRV was collected during all these maneuvers, as well as the performance data (the time it took to go through the emergency protocol and the subjective information from the flight simulator operator). Results regarding autonomic modulation showed a higher sympathetic response during the emergency maneuvers when compared to baseline. In some cases, there was also a higher sympathetic response during the emergency maneuvers when compared with the take-off protocol. Regarding performance data, the expert pilots accomplished the missions in less time than the rookie pilots. Autonomic modulation measured from HRV through portable devices can easily relay important information. This information is relevant since characterizing these maneuvers can provide helpful information to design training strategies to improve those psychophysiological responses

    360-Degree Complex Primary Reconstruction Using Porous Tantalum Cages for Adult Degenerative Spinal Deformity

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    Study Design: Retrospective cohort study. Objective: To assess both implant performance and the amount of correction that can be achieved using multilevel anterior lumbar interbody fusion (ALIF). Methods: Retrospective cohort study (n = 178) performed over a 4-year period. Surgical variables examined included blood loss, operative time, perioperative complications, and secondary/revision procedures. Follow-up radiographic assessment was performed to record implant-related problems. Radiographic parameters were examined pre- and postoperatively. Health-related quality of life (HRQOL) outcome measures were collected preoperatively and at 6 weeks, 6 months, 1 year, and 2 years postoperatively. Descriptive and comparative statistical analysis, using paired-sample t test and repeated-measures analysis of variance (rANOVA), was performed. Results: Lumbar lordosis increased from 42° ± 17° preoperatively to 55° ± 11° postoperatively (P < .001). The visual analog scale back pain mean score improved from 8.3 ± 1.5 preoperatively to 2.6 ± 2.4 at 2 years (P < .001). The mean Oswestry Disability Index improved from 69.5 ± 21.5 preoperatively to 19.9 ± 15.2 at 2 years (P < .001). The EQ-5D mean score improved from 0.2 ± 0.2 preoperatively to 0.8 ± 0.1 at 2 years (P = .02). There were no neurological, vascular, or visceral approach-related injuries reported. No rod breakages and no symptomatic nonunions occurred. There was one revision procedure performed for fracture. Conclusions: The use of porous tantalum cages as part of a 360-degree fusion to treat adult degenerative spinal deformity has been demonstrated to be a safe and effective strategy, leading to good clinical, functional, and radiographic outcomes in the short term

    Rapid Phenotype-Driven Gene Sequencing with the NeoSeq Panel: A Diagnostic Tool for Critically Ill Newborns with Suspected Genetic Disease

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    New genomic sequencing techniques have shown considerable promise in the field of neonatology, increasing the diagnostic rate and reducing time to diagnosis. However, several obstacles have hindered the incorporation of this technology into routine clinical practice. We prospectively evaluated the diagnostic rate and diagnostic turnaround time achieved in newborns with suspected genetic diseases using a rapid phenotype-driven gene panel (NeoSeq) containing 1870 genes implicated in congenital malformations and neurological and metabolic disorders of early onset (<2 months of age). Of the 33 newborns recruited, a genomic diagnosis was established for 13 (39.4%) patients (median diagnostic turnaround time, 7.5 days), resulting in clinical management changes in 10 (76.9%) patients. An analysis of 12 previous prospective massive sequencing studies (whole genome (WGS), whole exome (WES), and clinical exome (CES) sequencing) in newborns admitted to neonatal intensive care units (NICUs) with suspected genetic disorders revealed a comparable median diagnostic rate (37.2%), but a higher median diagnostic turnaround time (22.3 days) than that obtained with NeoSeq. Our phenotype-driven gene panel, which is specific for genetic diseases in critically ill newborns is an affordable alternative to WGS and WES that offers comparable diagnostic efficacy, supporting its implementation as a first-tier genetic test in NICUs

    Electrical Control of the Chemical Bonding of Fluorine on Graphene

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    We study the electronic structure of diluted F atoms chemisorbed on graphene using density functional theory calculations. We show that the nature of the chemical bonding of a F atom adsorbed on top of a C atom in graphene strongly depends on carrier doping. In neutral samples the F impurities induce a sp^3-like bonding of the C atom below, generating a local distortion of the hexagonal lattice. As the graphene is electron-doped, the C atom retracts back to the graphene plane and for high doping (10^14 cm^-2) its electronic structure corresponds to a nearly pure sp^2 configuration. We interpret this sp^3-sp^2 doping-induced crossover in terms of a simple tight binding model and discuss the physical consequences of this change.Comment: 4 pages, 4 figures. Accepted in Phys. Rev. B. Rapid Com

    Evaluación sistématica de la degradación de materiales sometidos al intemperismo

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    La necesidad de actividades de restauración y conservación del patrimonio deriva de la acción agresiva que ejercen los agentes ambientales sobre los materiales de construcción. En la actualidad, existen numerosos proyectos destinados a evaluar el comportamiento de estos materiales en ambientes de elevada agresividad, tales como las atmósferas marinas e industriales. Sin embargo, no se conocen iniciativas similares que estén orientadas al estudio de los deterioros que se producen en climas menos severos, y que en nuestro país representan las condiciones de una extensa región. Por otra parte, para diseñar las medidas de reparación y conservación de las construcciones resulta indispensable contar con herramientas que permitan evaluar en forma sistemática el comportamiento de los materiales y la evolución de los deterioros que ellos sufren, a fin de determinar las causas de degradación. Posteriormente, estas mismas herramientas deben permitir monitorear la efectividad de los métodos de reparación aplicados. Los profesionales que desean conocer con certeza el comportamiento de los materiales ante el paso del tiempo y su respuesta ante las distintas condiciones de exposición deben recurrir a datos suministrados por el fabricante o antecedentes existentes en la bibliografía específica y provenientes de investigaciones realizadas al respecto. Muchas de estas fuentes se encuentran desactualizadas, no corresponden a las condiciones de exposición específicas o bien carecen de valor técnico. El CECOVI, dentro de las actividades de investigación y desarrollo de materiales de construcción y sistemas constructivos que lleva adelante, está desarrollando un proyecto que tiene por objetivo principal el abordaje sistemático de la problemática de la durabilidad de los materiales de construcción sometidos a la acción de la intemperie y su aptitud en servicio. Este proyecto se circunscribe, actualmente, al estudio de la durabilidad de hormigones convencionales y elaborados con agregados livianos, hormigones celulares, madera, suelocemento y materiales plásticos, mientras que el tipo de exposición se limita a las condiciones de intemperismo habituales en un clima templado húmedo, de acuerdo a la clasificación establecida por el Sistema Internacional de Koeppen. Paralelamente, se realizan contrastes con materiales mantenidos en condiciones de laboratorio que actúan como patrones de comparación. Los ejes fundamentales planteados están constituidos por el análisis teórico, el seguimiento sistemático del comportamiento de materiales ante condiciones reales de exposición y en condiciones de envejecimiento acelerado, tendientes al establecimiento de una metodología de evaluación de aplicabilidad general, correlaciones entre el deterioro de los materiales y variables ambientales típicas de la región y el desarrollo de técnicas que permitan predecir su vida útil
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