1,699 research outputs found

    Pragmatic language disorder in Parkinson's disease and the potential effect of cognitive reserve

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    It is known that patients with Parkinson\u2019s Disease (PD) may show deficits in several areas of cognition, including speech and language abilities. One domain of particular interest is pragmatics, which refers to the capacity of using language in context for a successful communication. Several studies showed that some specific aspects of pragmatics \u2013 both in production and in comprehension \u2013 might be impaired in patients with PD. However, a clear picture of pragmatic abilities in PD is still missing, as most of the existing studies focused on specific aspects of the pragmatic competence rather than on sketching a complete pragmatic profile. Moreover, little is known on the potential role of protective factors in compensating the decline of communicative skills as the disease progresses. The present study has two aims: (1) to provide a complete picture of pragmatic abilities in patients with PD, by using a comprehensive battery (Assessment of Pragmatic Abilities and Cognitive Substrates, APACS) and by investigating the relationship with other aspects of cognitive functioning (e.g., working memory and Theory of Mind) and (2) to investigate whether Cognitive Reserve, i.e., the resilience to cognitive impairment provided by life experiences and activities, may compensate for the progressive pragmatic deficits in PD. We found that patients with PD, compared to healthy matched controls, had worse performance in discourse production and in the description of scenes, and that these impairments were tightly correlated with the severity of motor impairment, suggesting reduced intentionality of engaging in a communicative exchange. Patients with PD showed also an impairment in comprehending texts and humor, suggesting a problem in inferring from stories, which was related to general cognitive impairment. Notably, we did not find any significant difference between patients and controls in figurative language comprehension, a domain that is commonly impaired in other neurodegenerative diseases. This might be indicative of a specific profile of pragmatic impairment in patients with PD, worth of further investigation. Finally, Cognitive Reserve measures showed a high degree of association with pragmatic comprehension abilities, suggesting that the modification of life-styles could be a good candidate for compensating the possible problems in understanding the pragmatic aspects of language experienced by patients with PD

    steam turbine control valve and actuation system modeling for dynamics analysis

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    Abstract The paper describes a study conducted on Steam Turbine control valve and actuation systems, which rule the machine final power production and rotational speed. A dynamic model developed in the Matlab/Simulink environment is proposed to support the analysis of the operational stability of the hydro-mechanical system as well as the failure modes that it may face during operation. The model was validated through specific field tests conducted on the actuation system at a cogeneration plant in Nuovo Pignone, Florence. The proposed work also underlines the requirements that new actuation technologies should fulfil in order to meet control valve system performance criteria

    Designing epoxy viscosity for optimal mechanical performance of coated Glass Textile Reinforced Mortar (GTRM) composites

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    Preliminary epoxy coating of the reinforcing fabric provides an effective approach for improving matrix-to-fabric strength in inorganic matrix composites. We investigate the effect of epoxy resin dilution in acetone on uni-axial tensile performance of coated alkali-resistant (AR) glass fabric embedded in a lime-based matrix. Remarkably, it is found that dilution has a mixed effect on performance and this trend is consistently retrieved for strength, ductility and energy dissipation. Indeed, performance initially decays and then it suddenly raises to a level close to or even exceeding that of the undiluted specimens. It is postulated that this behaviour is caused by resin viscosity, that falls off exponentially with the dilution degree. Once a viscosity threshold is breached, epoxy is capable of penetrating inside the yarn and thereby prevents telescopic failure, that is the sliding of the outer over the inner glass filaments. Furthermore, the interphase surface area increases dramatically and this enhances performance and narrows scattering. Besides, optimal viscosity is reached at an unexpectedly high dilution degree, whence material cost is significantly reduced. A cost-to-performance comparison of common strengthening technologies is presented, which shows that diluted epoxy composites score comparably to FRPs. It is concluded that epoxy coating optimization plays an important role in designing inorganic matrix composites

    Effect of high temperature exposure on epoxy-coated glass textile reinforced mortar (GTRM) composites

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    An experimental investigation on the mechanical performance of epoxy-coated Alkali-Resistant (AR) glass textile reinforced mortar subjected to elevated temperature is presented. Two epoxy coatings are considered, which differ by the hardening agent alone. After 56 days dry curing, specimens are heated up to four different temperatures. After cooling down to ambient temperature, specimens are assessed in uni-axial tensile test according to Annex A of AC434. First cracking strength and elongation, ultimate tensile strength and elongation, cracked and uncracked moduli, transition point location and energy dissipation capability are evaluated. It is found that, in the explored temperature range, degradation is surprisingly mild and strongly dependent on the resin which is taken as coating agent. Indeed, temperature exposure may lead to strength enhancement. This positive outcome takes place at the expense of ductility and it is traced back, through Differential Scanning Calorimetry (DSC), to a post-curing process. Nonetheless, energy dissipation still decreases with temperature and, remarkably, with the same power-law behaviour for both resins. Such behaviour is compatible with a cumulative Weibull distribution, that is adopted in thermal damage models for resins, and it indicates that the underlying damage mechanism indeed operates on the resin at the fabric-to-matrix interface. (C) 2019 Elsevier Ltd. All rights reserved

    Effect of high temperature exposure on epoxy-coated glass textile reinforced mortar (GTRM) composites

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    An experimental investigation on the mechanical performance of epoxy-coated Alkali-Resistant (AR) glass textile reinforced mortar subjected to elevated temperature is presented. Two epoxy coatings are considered, which differ by the hardening agent alone. After 56 days dry curing, specimens are heated up to four different temperatures. After cooling down to ambient temperature, specimens are assessed in uni-axial tensile test according to Annex A of AC434. First cracking strength and elongation, ultimate tensile strength and elongation, cracked and uncracked moduli, transition point location and energy dissipation capability are evaluated. It is found that, in the explored temperature range, degradation is surprisingly mild and strongly dependent on the resin which is taken as coating agent. Indeed, temperature exposure may lead to strength enhancement. This positive outcome takes place at the expense of ductility and it is traced back, through Differential Scanning Calorimetry (DSC), to a post-curing process. Nonetheless, energy dissipation still decreases with temperature and, remarkably, with the same power-law behaviour for both resins. Such behaviour is compatible with a cumulative Weibull distribution, that is adopted in thermal damage models for resins, and it indicates that the underlying damage mechanism indeed operates on the resin at the fabric-to-matrix interface. (C) 2019 Elsevier Ltd. All rights reserved

    Effect of high temperature exposure on epoxy-coated glass textile reinforced mortar (GTRM) composites

    Get PDF
    An experimental investigation on the mechanical performance of epoxy-coated Alkali-Resistant (AR) glass textile reinforced mortar subjected to elevated temperature is presented. Two epoxy coatings are considered, which differ by the hardening agent alone. After 56 days dry curing, specimens are heated up to four different temperatures. After cooling down to ambient temperature, specimens are assessed in uni-axial tensile test according to Annex A of AC434. First cracking strength and elongation, ultimate tensile strength and elongation, cracked and uncracked moduli, transition point location and energy dissipation capability are evaluated. It is found that, in the explored temperature range, degradation is surprisingly mild and strongly dependent on the resin which is taken as coating agent. Indeed, temperature exposure may lead to strength enhancement. This positive outcome takes place at the expense of ductility and it is traced back, through Differential Scanning Calorimetry (DSC), to a post-curing process. Nonetheless, energy dissipation still decreases with temperature and, remarkably, with the same power-law behaviour for both resins. Such behaviour is compatible with a cumulative Weibull distribution, that is adopted in thermal damage models for resins, and it indicates that the underlying damage mechanism indeed operates on the resin at the fabric-to-matrix interface. (C) 2019 Elsevier Ltd. All rights reserved

    Designing epoxy viscosity for optimal mechanical performance of coated Glass Textile Reinforced Mortar (GTRM) composites

    Get PDF
    Preliminary epoxy coating of the reinforcing fabric provides an effective approach for improving matrix-to-fabric strength in inorganic matrix composites. We investigate the effect of epoxy resin dilution in acetone on uni-axial tensile performance of coated alkali-resistant (AR) glass fabric embedded in a lime-based matrix. Remarkably, it is found that dilution has a mixed effect on performance and this trend is consistently retrieved for strength, ductility and energy dissipation. Indeed, performance initially decays and then it suddenly raises to a level close to or even exceeding that of the undiluted specimens. It is postulated that this behaviour is caused by resin viscosity, that falls off exponentially with the dilution degree. Once a viscosity threshold is breached, epoxy is capable of penetrating inside the yarn and thereby prevents telescopic failure, that is the sliding of the outer over the inner glass filaments. Furthermore, the interphase surface area increases dramatically and this enhances performance and narrows scattering. Besides, optimal viscosity is reached at an unexpectedly high dilution degree, whence material cost is significantly reduced. A cost-to-performance comparison of common strengthening technologies is presented, which shows that diluted epoxy composites score comparably to FRPs. It is concluded that epoxy coating optimization plays an important role in designing inorganic matrix composites

    analysis of a simplified steam turbine governor model for power system stability studies

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    Abstract The present study describes an analysis performed on a simplified Steam Turbine governor model, which is useful for pre-tuning the machine regulation system. A dynamic model has been implemented in two different simulation tools, namely DigSILENT PowerFactory and Matlab/Simulink, to the aim of verifying the suitability of the latter one for power system stability studies. The proposed work paves the way to the wide range of possibilities connected to the integration of the machine governor model with other simulation blocks of a Combined Cycle Plant, by enabling the opportunity for pre-commissioning of the regulation system together with the analysis of the fulfillment of grid code regulations

    Effect of continuum couplings in fusion of halo 11^{11}Be on 208^{208}Pb around the Coulomb barrier

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    The effect of continuum couplings in the fusion of the halo nucleus 11^{11}Be on 208^{208}Pb around the Coulomb barrier is studied using a three-body model within a coupled discretised continuum channels (CDCC) formalism. We investigate in particular the role of continuum-continuum couplings. These are found to hinder total, complete and incomplete fusion processes. Couplings to the projectile 1p1/21p_{1/2} bound excited state redistribute the complete and incomplete fusion cross sections, but the total fusion cross section remains nearly constant. Results show that continuum-continuum couplings enhance the irreversibility of breakup and reduce the flux that penetrates the Coulomb barrier. Converged total fusion cross sections agree with the experimental ones for energies around the Coulomb barrier, but underestimate those for energies well above the Coulomb barrier.Comment: 15 pages, 7 figures, accepted in Phys. Rev.

    Dinámica estacional de Varroa destructor y Nosema sp en colonias de Apis mellifera en clima templado de Argentina

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    Los ectoparásitos obligados Varroa destructor y Nosema sp afectan la salud de la abeja de la miel Apis mellifera y genera importantes pérdidas de la colonia. Este artículo describe y analiza información proveniente de unidades centinelas sobre la distribución regional y los niveles de prevalencia de varrosis y nosemosis durante tres años, de acuerdo al programa de vigilancia de EEA INTA Rafaela y al programa de apicultura nacional de INTA. Durante el estudio, un total de 49 apiarios fueron monitoreados en 4 zonas diferentes de la Provincia de Santa Fe (zonas Norte, Sur, Costa y Centro), las cuales fueron visitadas en tres momentos diferentes del año: antes del tratamiento acaricida de otoño, después del tratamiento y al principio de primavera. Datos sobre las prácticas de manejo del apiario y muestras de ácaros de Varroa y Nosema fueron tomadas. Encontramos altos porcentaje de Varroa después del tratamiento en la Zona Sur durante 2017 y en la Zona Norte durante 2018 y 2019. Nuestros resultados sugieren que tanto la región como las estrategias de control impactan en los niveles de infestación de Varroa durante el transcurso del año, siendo su importancia relativa dependiente del momento en el que esto es observado. Además, la tendencia estacional de Varroa en respuesta a la dinámica de la población de abejas, explica la ausencia de interacción entre los factores período y año. De acuerdo a nuestro estudio, un programa de vigilancia por medio de apiarios centinela que identifique el período principal de propagación, fue efectivo en el monitoreo y remediación de los niveles de ambos patógenos, para asegurar una colonia de abejas saludable
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