Irregularity-Aware Bandlimited Approximation for Graph Signal Interpolation

In most work to date, graph signal sampling and reconstruction algorithms are intrinsically tied to graph properties, assuming bandlimitedness and optimal sampling set choices. However, practical scenarios often defy these assumptions, leading to suboptimal performance. In the context of sampling and reconstruction, graph irregularities lead to varying contributions from sampled nodes for interpolation and differing levels of reliability for interpolated nodes. The existing GFT-based methods in the literature make bandlimited signal approximations without considering graph irregularities and the relative significance of nodes, resulting in suboptimal reconstruction performance under various mismatch conditions. In this paper, we leverage the GFT equipped with a specific inner product to address graph irregularities and account for the relative importance of nodes during the bandlimited signal approximation and interpolation process. Empirical evidence demonstrates that the proposed method outperforms other GFT-based approaches for bandlimited signal interpolation in challenging scenarios, such as sampling sets selected independently of the underlying graph, low sampling rates, and high noise levels.Comment: Conference paper accepted for ICASSP 2024 (5 pages, 1 figure

Rate-Distortion Optimization With Alternative References For UGC Video Compression

User generated content (UGC) refers to videos that are uploaded by users and shared over the Internet. UGC may have low quality due to noise and previous compression. When re-encoding UGC for streaming or downloading, a traditional video coding pipeline will perform rate-distortion (RD) optimization to choose coding parameters. However, in the UGC video coding case, since the input is not pristine, quality ``saturation'' (or even degradation) can be observed, i.e., increased bitrate only leads to improved representation of coding artifacts and noise present in the UGC input. In this paper, we study the saturation problem in UGC compression, where the goal is to identify and avoid during encoding, the coding parameters and rates that lead to quality saturation. We proposed a geometric criterion for saturation detection that works with rate-distortion optimization, and only requires a few frames from the UGC video. In addition, we show how to combine the proposed saturation detection method with existing video coding systems that implement rate-distortion optimization for efficient compression of UGC videos.Comment: 5 pages, 6 figures, accepted at International Conference on Acoustics, Speech, & Signal Processing (ICASSP) 202

“¿Y qué es ser mapuche? ¿Y qué es ser winka?” Despliegues y negociaciones de identidad en espacios digitales de Facebook dedicados a la revitalización del mapudungun en Chile: un análisis glotopolítico

This paper is a concise qualitative analysis of discursive ideospaces, where people interested or involved in the management of Mapudungun (Mapuche language) confront and negotiate language ideologies in digital contexts concerning Chile, between 2015 and 2019. The corpus consists of a comment section from the Facebook group Aprender Mapudungun, where there are debates referring to discourses that explicitly demonstrate diverse language ideologies and their links with the extralinguistic within the context of Chile. We pay attention to how these ideologies, from linguistic agents and the general public, are coupled, confronted, or dialogued from the assumption of a conceptual contrast established in the relationship between the Mapuche and the Chilean/Winka, constituting complex and multidimensional visions. In this process, linguistic aspects are crucial, especially by means of the management of onomastics and the Mapudungun language.El presente trabajo es un breve análisis cualitativo de ideoespacios discursivos donde se confrontan y negocian diversas ideologías lingüísticas entre personas interesadas o involucradas en la gestión del mapudungun (lengua mapuche) en contextos digitales concernientes a Chile entre los años 2015 y 2019. En particular, el corpus corresponde a una sección de comentarios encontrada en el grupo de Facebook Aprender mapudungun, donde se debaten de manera explícita discursos demostrativos de diversas  ideologías lingüísticas y de sus vínculos con lo extralingüístico en el contexto del cierre nacional chileno. Ponemos atención a cómo dichas ideologías, tanto de parte de agentes lingüísticos como del público general, se acoplan, enfrentan o dialogan asumiendo una contraposición conceptual con respecto a la relación entre lo mapuche y lo chileno/lo winka, constituyendo visiones complejas y multidimensionales. En esto, lo lingüístico constituye un elemento fundamental, especialmente a través de la gestión de la onomástica y de la lengua mapuche

La diversidad de especies de vivientes corpóreos a la luz de la filosofía de Santo Tomás de Aquino

Beyond the theories and ideologies that sometimes are presented as inevitably linked to it, the truth is that the fact of evolution of living species is a highly relevant theoretical framework in modern biology. Therefore, any attempt to establish a fruitful dialogue between biology and Thomistic philosophy must address this issue; in order to advance in that direction, however, one should answer first the question about the diversity of species of living beings, a controversial topic among Thomistic scholars. In this article we argue that the multiplicity of biological species is compatible and consistent with the metaphysical scheme proposed by Thomas Aquinas; moreover, we think that this thesis was suggested by Aquinas himself in some passages of his work, though certainly not in an evolutionary context. As Saint Thomas repeatedly points out, in most cases we do not know the specific difference included in the definition of these species. This, however, does not imply our absolute ignorance about them; we think, on the contrary, that the philosophical examination of vital operations may constitute a valid strategy for advancing, at least partially, in the distinction of certain species of corporeal living beings. In the final section of the article we apply this principle in the philosophical analysis of the criterion of interbreeding that biologists commonly use to develop their taxonomic classifications. Más allá de las teorías e ideologías que a veces se presentan como indisolublemente ligadas a él, lo cierto es que el hecho de la evolución de los seres vivos ha llegado a constituir un marco teórico sumamente relevante para la biología moderna. Un intento serio de establecer un diálogo fructífero entre la biología y la filosofía tomista, por lo tanto, debe enfrentar esta cuestión. Para avanzar en dicha dirección, empero, debe antes abordarse el interrogante referida a la diversidad específica de los vivientes, un tópico controversial entre los estudiosos del pensamiento de Tomás de Aquino. En este artículo argumentamos que la multiplicidad de especies biológicas es una tesis no solo compatible y consistente con el esquema metafísico tomista, sino que más aún, fue sugerida por el Aquinate en algunos pasajes de su obra, aunque no, por supuesto, en un contexto evolutivo. Como lo señala repetidamente Santo Tomás, en una mayoría de los casos desconocemos la diferencia específica incluida en la definición de estas especies. De ello, no obstante, no se sigue nuestra absoluta ignorancia al respecto; sostenemos, en cambio, que el examen filosófico de las operaciones vitales puede constituir una estrategia válida para avanzar, al menos parcialmente, en la distinción de ciertas especies de vivientes corpóreos. En la sección final del artículo aplicamos este principio para examinar filosóficamente el criterio de la interfecundidad que los biólogos utilizan frecuentemente para elaborar sus clasificaciones taxonómicas

EVIDENCE OF HIGH CONSUMPTION OF WASTE BY THE ANDEAN CONDOR (VULTUR GRYPHUS) IN AN ANTHROPIZED ENVIRONMENT OF CHILE

Abstract · Anthropogenic food subsidies and waste disposals have become a new food resource for wildlife, including the Andean Condor (Vultur gryphus), a situation that implies benefits and health risks. To increase understanding of Andean Condor feeding habits in the most anthropized area in Chile, we analyzed 280 pellets collected during 2016 from one roost in the Metropolitan Region, central Chile. We identified the main diagnostic elements microscopically and expressed them as percentage of occurrence (percentage of each item in relation to all pellets). We found 12 prey categories (including mammals, birds, and plant material) and 9 waste categories. Condors fed mainly on mammals (99%); livestock was their main feeding source (52%), followed by native (22%) and exotic wild species (19%). Birds were detected less frequently (8%). We found a high occurrence of waste (31%), of which plastic remains were the main item (27%). According to our results, landfills serve as a complementary food source for condors, probably a low-quality but easily accessible, and which exposes them to a variety of health and mortality risks. Despite the fact that Andean Condors can reach distant places in foraging flights to find food resources, a high proportion of the population is attracted to rubbish dumps and landfills. Despite the spatio-temporal limitations of our results, this is the first record that describes and quantifies a high presence of waste as a component of the Andean Condor diet. We recommend a more comprehensive study to assess their feeding habits and habitat preferences in a broader spatio-temporal context, and to determine the possible impact of the use of waste disposals on Andean Condor populations.Resumen · Evidencia de alto consumo de basura por el Cóndor Andino (Vultur gryphus) en un ambiente antropizado de Chile Los subsidios antropogénicos y sitios de disposición de basura se han convertido en una nueva fuente de alimentación para la fauna, incluido el Cóndor Andino (Vultur gryphus), lo que implica beneficios y riesgos. Con el fin de estudiar los hábitos alimenticios del cóndor andino en un área altamente antropizada, analizamos 280 egagrópilas colectadas durante 2016 en un dormidero de la Región Metropolitana, en Chile central. Identificamos microscópicamente los principales elementos diagnósticos y los expresamos como porcentaje de ocurrencia (porcentaje de cada ítem respecto del total de pellet). Encontramos 12 ítems dietarios (incluyendo mamíferos, aves y materia vegetal) y 9 ítems de basura. Los cóndores se alimentaron principalmente de mamíferos (99%); el ganado fue la principal fuente de alimento (52%), seguido por especies silvestres nativas (22%) y exóticas (19%), mientras que las aves estuvieron escasamente representadas (8%). Encontramos una alta ocurrencia de basura (31%), de la cual los restos de plástico fueron el principal ítem (27%). De acuerdo a nuestros resultados, los basurales sirven como una fuente complementaria de alimentación para los cóndores, probablemente de baja calidad, pero de fácil acceso, y que los expone a una variedad de riesgos de mortalidad y para su salud. Aunque el Cóndor Andino puede alcanzar lugares distantes en sus vuelos de forrajeo, una alta proporción de su población es atraída a vertederos y rellenos sanitarios. A pesar de las limitaciones espaciotemporales de nuestros resultados, este es el primer registro que describe y cuantifica la alta presencia de basura como componente de la dieta del Cóndor Andino. Recomendamos ampliar el estudio para evaluar sus hábitos alimentarios y preferencias de hábitat en un contexto espacial y temporal amplio y poder determinar el posible impacto del uso de basurales en poblaciones de Cóndor Andino