Quantum quenches in disordered systems: Approach to thermal equilibrium without a typical relaxation time

We study spectral properties and the dynamics after a quench of one-dimensional spinless fermions with short-range interactions and long-range random hopping. We show that a sufficiently fast decay of the hopping term promotes localization effects at finite temperature, which prevents thermalization even if the classical motion is chaotic. For slower decays, we find that thermalization does occur. However, within this model, the latter regime falls in an unexpected universality class, namely, observables exhibit a power-law (as opposed to an exponential) approach to their thermal expectation values.Comment: 5 pages, 5 figure

Synthesis and Characterization of S-IPN Hydrogels of Chitosan/PVA/PNIPAm to be Used in the Design of Nucleus Pulposus Prosthesis

Hydrogels (HG) have been widely used in biomedical applications due to their high-water content which improves their biocompatibility with living tissue. In this study, Chitosan (CS) hydrogels cross-linked with Genipin and semi interpenetrated network (S-IPN) with PVA/PNIPAm were prepared to be used in the design of nucleus pulposus (NP) prosthesis. Chemical structure, morphology, swelling ratio (SR), mechanical properties and cytotoxicity were evaluated through a variation of the Genipin percentage and CS/PVA/PNIPAm proportions. Those experiments were carried out through Fourier-Transform Infrared Spectroscopy, Scanning Electron Microscopy, swelling studies, dynamic rheology, and hemocompatibility tests. The results showed that regardless of the Genipin percentage or polymers proportions, all HGs had interconnective porous structure. What did change microstructurally, was the pore size, its size distribution and the wall thickness. Firstly, an increment in the Genipin percentage and in the CS proportion concluded in an augmentation of the pore size. Secondly, an augmentation in the PVA proportion ended up producing smaller pores, with larger wall thickness and more homogeneous pore size distribution. The variation in PNIPAm proportion didn´t influence the morphology, but did have an impact on the SR and storage modulus (G´) augmenting in both cases as the PNIPAm proportion. The swelling ratio turned out to be related to the pore morphology; as smaller the pore size, smaller the SR. Likewise, the storage modulus rose insofar the SR diminished. In these S-IPN HGs, G´ varied between 77 Pa and 27000 Pa, values below and above G´ reported for human NP. Also, ? varied between 1.4° and 13.17° while the ? reported for NP is 23°-31°. Finally, the hemocompatibility tests did not show cellular lysis for any formulation. These outcomes demonstrated that from the rheological and hemocompatibility point of view, this kind of as semi interpenetrated networks (S-IPNs) HGs can be tailored to attain the NP´s propertie

Between culture and the market: what do physics teachers take into account when choosing their textbooks?

Here we present some results of an ongoing study into the processes by which secondary school teachers choose physics textbooks, in this case, teachers from Brazil and Portugal. The objective is to understand what teachers take into account when selecting a physics textbook. To contextualise the study, the development and presence of physics textbooks in Brazil in the period between the mid-nineteenth century and the present day is discussed. These reflections highlight how cultural, economic, political and social factors are carried through to educational expressions. We show that the production of physics textbooks went through three periods, according to the pedagogical conception prevailing at each time. This research is based on the assumption that these books should be understood as elements of the school culture, being identified as cultural products as well as commodities. These dimensions have been little explored in research on textbooks, so this work presents a unique discussion that reflects on the relationship between culture and the market in order to understand physics textbooks from a structural perspective

Linear dynamic harmonic regression

Among the alternative unobserved components formulations within the stochastic state space setting, the dynamic harmonic regression (DHR) model has proven to be particularly useful for adaptive seasonal adjustment, signal extraction, forecasting and back-casting of time series. First, it is shown how to obtain AutoRegressive moving average (ARMA) representations for the DHR components under a generalized random walk setting for the associated stochastic parameters; a setting that includes several well-known random walk models as special cases. Later, these theoretical results are used to derive an alternative algorithm, based on optimization in the frequency domain, for the identification and estimation of DHR models. The main advantages of this algorithm are linearity, fast computational speed, avoidance of some numerical issues, and automatic identification of the DHR model. The signal extraction performance of the algorithm is evaluated using empirical applications and comprehensive Monte Carlo simulation analysis

Analyzing the Importance of Marking Links to Special Targets in Mobile Web

Literature points out the importance of indicating when a link opens a different website in a new window, since this is the default behavior that users expect, but this problem has not been specifically studied in mobile devices yet. This paper explains a study that was carried out with 20 different mobile devices and 19 users. We compared the usability of opening links in the same window or in a new one, informing or not informing the user about the target, as well as the convenience of using icons or text to inform about the target of a link. Results show that 95% of the devices used for the experiment had browser multi-window support, and we conclude that mobile users prefer to be previously informed when a link opens in a new window, and that the preferred method for informing them is using an icon instead of a text

On the development of a technological solution for long-term preservation of the commercial qualities in live oysters

The Pacific Oyster has adapted well to the southern Brazilian environmental conditions, where the combination of factors allows harvest in less than eight months. Although convenient for most of the year, it is during summer that water temperature can exceed 30 ºC, a summer condition that leads to high mortality rates. According to the literature, if spawning is not triggered, a substantial reduction in mortality can be achieved. Studies previously presented at CYTEF 2020 showed that confining oysters at temperatures close to those of basal metabolism can inhibit the effects of gametogenesis. Further research was conducted in order to verify the possible outcomes of long term confinement of late autumn harvested oysters, presenting high glycogen reserves. This article reports the experimental results of those tests, regarding the preservation of quality attributes and the reduction of mortality rates, when confining oysters under temperatures similar to those of basal metabolism regime

A New Competence-based Approach for Personalizing MOOCs in a Mobile Collaborative and Networked Environment

Massive Open Online Courses (MOOCs) are a new disruptive development in higher education that combines openness and scalability in a most powerful way. They have the potential to widen participation in higher education. Thus, they contribute to social inclusion, the dissemination of knowledge and pedagogical innovation and also the internationalization of higher education institutions. However, one of the critical elements for a massive open language learning experience to be successful is to empower learners and to facilitate networked learning experiences. In fact, MOOCs are designed for an undefined number of participants, thus serving a high heterogeneity of profiles, with diverse learning styles and prior knowledge, and also contexts of participation and diversity of online platforms. Personalization can play a key role in this process. The iMOOC pedagogical model introduced the notion of diversity to MOOC design, allowing for a clear differentiation of learning paths and also virtual environments. In this article, the authors present a proposal based on the iMOOC approach for a new framework for personalizing and adapting MOOCs designed in a collaborative, networked pedagogical approach by identifying each participant's competence profile and prior knowledge, as well as the respective mobile communication device used to generate matching personalized learning. This article also shows the results obtained in a laboratory environment after an experiment has been performed with a prototype of the framework. It can be observed that creating personalized learning paths is possible and the next step is to test this framework with real experimental groups.Los cursos en línea masivos y abiertos (MOOC) son una nueva tendencia rompedora en la educación superior. Estos cursos combinan la propiedad de ser abiertos con la posibilidad de ser escalables de una forma muy potente. Tienen el potencial de permitir la participación en la educación superior para todas las personas, a todos los niveles. Por lo tanto, contribuyen a la inclusión social, la difusión del conocimiento y la innovación pedagógica, así como la internalización de las instituciones de educación superior. Sin embargo, uno de los elementos críticos para que tenga éxito una experiencia de aprendizaje de forma abierta y masiva es potenciar y facilitar una red de aprendizaje. De hecho, los MOOC no están diseñados para un número predefinido de participantes por lo que sirven para un alto número de perfiles heterogéneos, con diversidad de estilos de aprendizaje y conocimientos previos, pero también contextos de participación y diversidad de plataformas online. La personalización puede desempeñar un papel clave en este proceso. El modelo pedagógico iMOOC introdujo el principio de diversidad en el diseño de MOOC, permitiendo una clara diferenciación de caminos de aprendizaje y también entornos virtuales. En este artículo los autores presentan una propuesta basada en el enfoque de iMOOC, sobre un nuevo sistema para la personalización y adaptación de MOOC diseñados en un enfoque colaborativo y en una red pedagógica. El mecanismo es identificar cada competencia del perfil de los participantes, el conocimiento previo que estos tienen así como detectar sus respectivos dispositivos móviles, y se genera un camino de aprendizaje personalizado en base a estos parámetros. Este artículo también muestra los resultados obtenidos en un entorno de laboratorio después de un experimento llevado a cabo con un prototipo del sistema. Se puede observar que es posible crear caminos de aprendizaje personalizados y que el siguiente paso es probar este sistema con grupos experimentales reales

Distribuição dos intervalos do piscar espontâneo em medidas repetidas com e sem anestesia tópica ocular

PURPOSE: To determine if the distribution of inter-blink time intervals is constant with repeated measurements with and without topical ocular anesthesia. METHODS: Inter-blink time was measured in 15 normal subjects ranging from 19 to 32 years (mean ± SD= 23.9 ± 3.20) with the magnetic search coil technique on 3 different occasions, the last one with topical ocular anesthesia. RESULTS: One-way analysis of variance for repeated measurements showed that topical anesthesia significantly reduced the blink rate (blinks per minute), which was constant in the first two measurements (F=8.27, p=0.0015. First measurement: mean ± SD= 13.7 ± 7.8; second measurement: 13.1 ± 8.5 SD; with topical anesthesia: = 7.2 ± 4.6). However, distributions shape was not affected when the blink rate was reduced. The three distributions followed a Log Normal pattern, which means that the time interval between blinks was symmetrical when the time logarithm was considered. CONCLUSIONS: Topical ocular anesthesia reduces the rate of spontaneous blinking, but does not change the distribution of inter-blink time interval.OBJETIVOS: Determinar se a distribuição dos intervalos do piscar espontâneo se mantém em medidas repetidas com e sem anesthesia tópica ocular. MÉTODOS: Os intervalos entre movimentos de piscar da pálpebra superior foram medidos com rastreamento magnético (Magnetic Search Coil) em 15 sujeitos (11 do sexo masculino) normais com idades entre 19 a 32 anos (média 23,86 ± 3,20 dp anos). RESULTADOS: Análise de variância unifatorial para medidas repetidas mostrou que a anesthesia tópica ocular diminuiu significativamente a frequência média (número de blinks/minuto) do piscar espontâneo, a qual se manteve constante nas duas primeiras medidas (F=8,27, p=0,0015. Primeira medida 13,7 ± 7,8 DP; segunda medida 13,1 ± 8,5; com anestesia tópica 7,2 ± 4,6). No entanto, a forma da distribuição nas 3 medidas obedeceu uma distribuição do tipo Log Normal, de modo que os intervalos de piscar foram normalmente distribuídos quando o logaritmo do intervalo foi considerado. CONCLUSÕES: A anesthesia tópica ocular diminui significativamente a frequência de piscar, mas não altera a distribuição dos intervalos do piscar espontâneo

Processing speed in relapsing-remitting multiple sclerosis: the role played by the depressive symptoms

Introducción. La disminución de la velocidad de procesamiento parece ser una característica neuropsicológica prototípica en la esclerosis múltiple (EM). Sin embargo, el impacto de los frecuentes síntomas depresivos de estos pacientes sobre la velocidad de procesamiento aún no se ha definido con precisión, debido a algunas limitaciones metodológicas presentes en la mayoría de los estudios previos. Sujetos y métodos. Cuarenta y dos pacientes con EM remitente recurrente, 20 con síntomas depresivos (inventario de depresión de Beck > 13) y 22 sin ellos, fueron comparados con 24 controles sanos en tests neuropsicológicos de velocidad de procesamiento –Symbol Digit Modality Test (SDMT), test de Stroop, Trail Making Test (TMT) y Paced Auditory Serial Addition Test-batería neuropsicológica breve (PASAT-BNB)–. Resultados. Los pacientes con EM sin síntomas depresivos realizaron significativamente peor que los controles los tests de Stroop –palabra (P), color (C) y palabra-color (PC)– y PASAT-BNB (tiempo de ejecución), mientras que los pacientes con síntomas depresivos obtuvieron puntuaciones significativamente peores que los controles sanos en Stroop (P, C y PC), SDMT, TMT (A, B y B-A) y PASAT-BNB (tiempo de ejecución y errores). La ejecución de los pacientes con EM y síntomas depresivos fue significativamente peor que la de los pacientes sin síntomas depresivos en el SDMT, TMT (A, B y B-A) y PASAT-BNB (tiempo de ejecución). Conclusiones. El impacto de la enfermedad no se evidenció de forma generalizada en el rendimiento neuropsicológico de los pacientes con EM remitente recurrente. Los síntomas depresivos parecen desempeñar un papel importante en la determinación de los déficits de velocidad. Mientras que la EM redujo la velocidad de procesamiento, los síntomas depresivos en la EM se asociaron a un déficit específico en ciertos procesos cognitivos diferentes de los de velocidadIntroduction. Reduced speed of information processing seems to characterize neuropsychological performance in multiple sclerosis (MS) patients. However, the impact in speed of information processing of depressive symptoms, that are highly prevalent in this population, has not been precisely defined yet due to the presence of some methodological limitations in most preceding studies. Subjects and methods. 42 MS remittent recurrent patients, 20 with depressive symptoms (BDI > 13), and 22 without, were compared to 24 healthy controls in neuropsychological tasks of speed of processing (SDMT, Stroop, TMT y PASAT-BNB). Results. MS patients without depressive symptoms performed significantly worse than healthy controls the Stroop (W, C and WC), and the PASAT-BNB (execution time) tests. MS patients with depressive symptoms performed significantly worse than healthy controls the Stroop (W, C and WC), SDMT, TMT (A, B and B-A), and the PASAT-BNB (execution time and errors) tests. MS patients with depressive symptoms performed significantly worse than MS patients without depressive symptoms the SDMT, TMT (A, B and B-A), and the PASAT-BNB (execution time) tests. Conclusions. MS impact was not generalized in neuropsychological performance of patients. Depressive symptoms seem to play and important role determining the speed deficit. While MS reduced speed of information processing, depressive symptoms were associated to specific cognitive deficit different from speed onesParcialmente financiado por el Ministerio de Ciencia e Innovación (PSI2009-14415-C03-03) y por Merck-Seron

Identity Of Physical Education Teachers In Higher Education: Epistemological And Substantive Aspects Of Commodification Of Education

Based on the assumption that contemporary society's complexity challenges subjects in many ways, we investigated the construction of university professors' identity. To this end, we chose the oral history method to investigate the constitution of the identity of the professor in charge of didactic and pedagogical subjects in PE courses in the city of Sorocaba, SP, Brazil. Analyses based on Cultural Studies assumptions and divided into epistemological and substantive aspects indicate strong presence of uncritical and solitary teacher identities, as a result of life histories and subjectivities constituted by power relations and socio-historical processes that commodify education and lead to alienating practices in higher education institutions. The strategies to overcome that situation include continued expansion of the academic debate using contemporary theoretical tools that give visibility to knowledge produced in the school context.22378379