Bounded and unbounded polynomials and multilinear forms: Characterizing continuity

In this paper we prove a characterization of continuity for polynomials on a normed space. Namely, we prove that a polynomial is continuous if and only if it maps compact sets into compact sets. We also provide a partial answer to the question as to whether a polynomial is continuous if and only if it transforms connected sets into connected sets. These results motivate the natural question as to how many non-continuous polynomials there are on an infinite dimensional normed space. A problem on the \emph{lineability} of the sets of non-continuous polynomials and multilinear mappings on infinite dimensional normed spaces is answered.Comment: 8 page

COVID-19 Lockdown and Disney+ strategy on social networks on its launch during the State of alarm in Spain

The launch of Disney+ in Spain in March 2020 coincided with the Covid-19 pandemic and a period of home confinement for many Spaniards. This study examines the advertising and engagement strategy used by Disney+ on Twitter and Instagram, analyzing 2,268 messages. The platform’s social media use is similar to that of its competitors, with Twitter used for user engagement and Instagram used for content promotion. However, the study finds that the platform missed the opportunity to emphasize its unique qualities and appeal to the brand’s values. Despite this, Disney+ generated significant engagement during its launch month, reflecting high levels of user anticipation. Popular original productions such as The Mandalorian and Aladdin, as well as acquired content like The Simpsons, indicate the brand’s focus on a family or broad-spectrum target audience, in contrast to the younger and niche audiences favored by its competitors.La llegada de Disney+ a España en marzo de 2020 estuvo marcada por la pandemia del Covid-19. El periodo de confinamiento domiciliario entre la población española coincidió con la irrupción del nuevo servicio streaming de una de las marcas más conocidas y queridas a nivel mundial. Este estudio analiza la estrategia publicitaria y de engagement empleada por Disney+ en Twitter e Instagram. El análisis de contenido incluye 2.268 mensajes. Se aprecia un uso de las redes sociales similar a marcas competidoras como Netflix con un uso de Twitter para informar y responder a los comentarios de los usuarios; mientras que de Instagram se promueven nuevos contenidos, en especial películas. Se observa que en el intento de destacar sus elementos diferenciales como servicio bajo demanda, se pierde la oportunidad de apelar a los valores propios de la marca del ratón. La plataforma consiguió un mejor engagement durante el mes de lanzamiento, lo que muestra la alta expectativa de los usuarios. Entre las publicaciones más virales se encuentran producciones originales como The Mandalorian o Aladdín, pero también productos adquiridos como Los Simpson, y que apuntan al interés de la marca por un target familiar o de amplio espectro, frente a audiencias más jóvenes y de nicho valoradas por la competencia

Management of coastal dunes affected by shrub encroachment: are rabbits an ally or an enemy of restoration?

In coastal dunes, shrub encroachment disrupts natural disturbance, and reduces habitat heterogeneity and species composition. In this paper, we implemented a pilot scale trial aimed at restoring coastal dunes affected by the encroachment by the shrub Retama monosperma (hereinafter Retama) as well as strengthening the populations of Thymus carnosus (regionally cataloged as ‘Critically Endangered’). A total 3 ha of Retama shrub was clearcut in two sites with different Retama cover (54 and 72%). The effect of rabbits on vegetation recovery was assessed by placing exclosures both in treated and untreated plots in Spring, 2015. Plant composition, species richness and diversity were evaluated two years after treatments (with and without Retama clearing, and with and without rabbit exclusion). Retama clearing alone did not allow the recovery of plant composition typical of gray dunes two-years after treatments, but resulted in a biodiversity loss within the Retama understorey when rabbits were present. However, Retama clearing resulted in a significant vigor improvement of T. carnosus in the site with the highest density of Retama. Rabbit exclusion significantly increased species richness and Shannon-Wiener diversity index, and allowed the recovery of plant composition typical of gray dunes. The results suggest that shrub encroachment caused by Retama has a long-lasting negative impact on dune vegetation and that periodic clearing should be combined with rabbit exclusion at least during early restoration stages of dune vegetation. To recover the population of T. carnosus, Retama should be prevented from reaching high cover and periodic clearing without rabbit exclusion is suggested

Deep Spiking Neural Network model for time-variant signals classification: a real-time speech recognition approach

Speech recognition has become an important task to improve the human-machine interface. Taking into account the limitations of current automatic speech recognition systems, like non-real time cloud-based solutions or power demand, recent interest for neural networks and bio-inspired systems has motivated the implementation of new techniques. Among them, a combination of spiking neural networks and neuromorphic auditory sensors offer an alternative to carry out the human-like speech processing task. In this approach, a spiking convolutional neural network model was implemented, in which the weights of connections were calculated by training a convolutional neural network with specific activation functions, using firing rate-based static images with the spiking information obtained from a neuromorphic cochlea. The system was trained and tested with a large dataset that contains ”left” and ”right” speech commands, achieving 89.90% accuracy. A novel spiking neural network model has been proposed to adapt the network that has been trained with static images to a non-static processing approach, making it possible to classify audio signals and time series in real time.Ministerio de Economía y Competitividad TEC2016-77785-

Amyloid beta and diabetic pathology cooperatively stimulate cytokine expression in an Alzheimer's mouse model

Background Diabetes is a risk factor for developing Alzheimer's disease (AD); however, the mechanism by which diabetes can promote AD pathology remains unknown. Diabetes results in diverse molecular changes in the brain, including dysregulation of glucose metabolism and loss of cerebrovascular homeostasis. Although these changes have been associated with increased A beta pathology and increased expression of glial activation markers in APPswe/PS1dE9 (APP/PS1) mice, there has been limited characterization, to date, of the neuroinflammatory changes associated with diabetic conditions. Methods To more fully elucidate neuroinflammatory changes associated with diabetes that may drive AD pathology, we combined the APP/PS1 mouse model with either high-fat diet (HFD, a model of pre-diabetes), the genetic db/db model of type 2 diabetes, or the streptozotocin (STZ) model of type 1 diabetes. We then used a multiplexed immunoassay to quantify cortical changes in cytokine proteins. Results Our analysis revealed that pathology associated with either db/db, HFD, or STZ models yielded upregulation of a broad profile of cytokines, including chemokines (e.g., MIP-1 alpha, MIP-1 beta, and MCP-1) and pro-inflammatory cytokines, including IL-1 alpha, IFN-gamma, and IL-3. Moreover, multivariate partial least squares regression analysis showed that combined diabetic-APP/PS1 models yielded cooperatively enhanced expression of the cytokine profile associated with each diabetic model alone. Finally, in APP/PS1xdb/db mice, we found that circulating levels of A beta 1-40, A beta 1-42, glucose, and insulin all correlated with cytokine expression in the brain, suggesting a strong relationship between peripheral changes and brain pathology. Conclusions Altogether, our multiplexed analysis of cytokines shows that Alzheimer's and diabetic pathologies cooperate to enhance profiles of cytokines reported to be involved in both diseases. Moreover, since many of the identified cytokines promote neuronal injury, A beta and tau pathology, and breakdown of the blood-brain barrier, our data suggest that neuroinflammation may mediate the effects of diabetes on AD pathogenesis. Therefore, strategies targeting neuroinflammatory signaling, as well as metabolic control, may provide a promising strategy for intervening in the development of diabetes-associated AD

The genetic landscape of the Iberian red deer (Cervus elaphus hispanicus) after 30 years of big-game hunting in southern Spain

© 2015 The Wildlife Society. The Iberian red deer (Cervus elaphus hispanicus) suffered a striking collapse of its populations during the first half of the 20th century due to excessive hunting. In Andalusia, southern Spain, re-colonization took place from a few relict populations through natural dispersal, and through artificial reintroductions for big-game hunting. How the population decline influenced genetic diversity, and its current distribution after the re-colonization and intensive hunting practices are unclear. We addressed these questions by analyzing nuclear microsatellite variability from 58 red deer populations distributed throughout Andalusia. Our results showed a relatively high genetic variability spatially structured into 5 clusters, corresponding to the locations of relict populations. This indicates that the red deer's current genetic background has presumably retained much of the genetic variation present in those relict populations. We also found that a substantial portion (32%) of the populations displays some degree of inbreeding. We suggest that new herds should be established using individuals from the different genetic clusters, and a careful monitoring of the breeder's genetic background to prevent further inbreeding and inadvertent hybridization. Failure to do so could lead to loss of genetic diversity and the dilution of the genetic identity of the Iberian red deer.Peer Reviewe

Linking gas and particle ejection dynamics to boundary conditions in scaled shock-tube experiments

Predicting the onset, style and duration of explosive volcanic eruptions remains a great challenge. While the fundamental underlying processes are thought to be known, a clear correlation between eruptive features observable above Earth's surface and conditions and properties in the immediate subsurface is far from complete. Furthermore, the highly dynamic nature and inaccessibility of explosive events means that progress in the field investigation of such events remains slow. Scaled experimental investigations represent an opportunity to study individual volcanic processes separately and, despite their highly dynamic nature, to quantify them systematically. Here, impulsively generated vertical gas-particle jets were generated using rapid decompression shock-tube experiments. The angular deviation from the vertical, defined as the \textquotedblspreading angle\textquotedbl, has been quantified for gas and particles on both sides of the jets at different time steps using high-speed video analysis. The experimental variables investigated are 1) vent geometry, 2) tube length, 3) particle load, 4) particle size, and 5) temperature. Immediately prior to the first above-vent observations, gas expansion accommodates the initial gas overpressure. All experimental jets inevitably start with a particle-free gas phase (gas-only), which is typically clearly visible due to expansion-induced cooling and condensation. We record that the gas spreading angle is directly influenced by 1) vent geometry and 2) the duration of the initial gas-only phase. After some delay, whose length depends on the experimental conditions, the jet incorporates particles becoming a gas-particle jet. Below we quantify how our experimental conditions affect the temporal evolution of these two phases (gas-only and gas-particle) of each jet. As expected, the gas spreading angle is always at least as large as the particle spreading angle. The latter is positively correlated with particle load and negatively correlated with particle size. Such empirical experimentally derived relationships between the observable features of the gas-particle jets and known initial conditions can serve as input for the parameterisation of equivalent observations at active volcanoes, alleviating the circumstances where an a priori knowledge of magma textures and ascent rate, temperature and gas overpressure and/or the geometry of the shallow plumbing system is typically chronically lacking. The generation of experimental parameterisations raises the possibility that detailed field investigations on gas-particle jets at frequently erupting volcanoes might be used for elucidating subsurface parameters and their temporal variability, with all the implications that may have for better defining hazard assessment. Supplementary Information The online version contains supplementary material available at 10.1007/s00445-021-01473-0