Hardy type spaces on certain noncompact manifolds and applications

In this paper we consider a complete connected noncompact Riemannian manifold M with Ricci curvature bounded from below, positive injectivity radius and spectral gap b. We introduce a sequence X^1(M), X^2(M), ... of new Hardy spaces on M, the sequence Y^1(M/, Y^2(M), ... of their dual spaces, and show that these spaces may be used to obtain endpoint estimates for purely imaginary powers of the Laplace-Beltrami operator and for more general spectral multipliers associated to the Laplace--Beltrami operator L on M. Under the additional condition that the volume of the geodesic balls of radius r is controlled by C r^a e^{2\sqrt{b} r} for some real number a and for all large r, we prove also an endpoint result for first order Riesz transforms D L^{-1/2}. In particular, these results apply to Riemannian symmetric spaces of the noncompact type.Comment: 27 pages, v2: the first version has been revised and rearranged, with additions, in two papers, of which this new version is the first. The second paper is posted as arXiv:1002.1161v

Políticas de movilidad y gestión de la pandemia en ciudades latinoamericanas

Hoy las ciudades de América Latina tal vez están enfrentando el reto de salud y gobernanza más crítico de este siglo, la pandemia de COVID-19. En cinco meses el mundo urbano ha pasado de una dinámica de incesante movimiento a una de movimiento regulado. Para controlar la pandemia, los agentes públicos han pedido a la población estar en casa, evadir espacios públicos o privados de gran aglomeración de personas y, limitar los sistemas de transporte masivo y colectivo. Todas estas respuestas están reconfigurando drásticamente la movilidad urbana y exigiendo la construcción de nuevas herramientas de gobernanza. El objetivo de este trabajo es proponer una investigación orientada a determinar cuál es el papel que las políticas publicas de movilidad, implementadas durante la pandemia, tienen en la reducción de la mortalidad y expansión del contagio en diversas ciudades latinoamericanas. Para esto, planteamos dos tipos de análisis: 1) del contenido de políticas públicas y 2) de la correlación entre estas medidas y los resultados del contagio. Al final se logra evidenciar que, si bien la expansión de la pandemia está asociada a redes globales, las respuestas de gobernanza urbana adoptadas localmente tienen alta variabilidad tanto de estrategias como de resultados en la gestión de la pandemia

Reconfiguraci\uf3n de Entornos Peatonales: Una propuesta de dise\uf1o aplicada a corredores del centro tradicional de Medell\uedn

El auge de la movilidad vehicular durante el siglo XX signific\uf3 el reemplazo progresivo de la movilidad peatonal y de una acci\uf3n primaria del individuo: el caminar. Sin embargo, los conflictos generados por el crecimiento urbano y el deterioro ambiental han tra\ueddo cuestionamientos acerca de las formas de pensar e intervenir nuestras ciudades dando lugar a una transformaci\uf3n gradual de paradigmas de movilidad. Hoy, la movilidad peatonal y la movilidad no motorizada se han vuelto temas recurrentes, tanto en agendas p\ufablicas como en la construcci\uf3n del espacio urbano, visibilizando una importante variedad de reflexiones sobre el dise\uf1o, la calidad y la experiencia espacial. Para evidenciar la importancia de los entornos peatonales como espacio clave de las practicas cotidianas de movilidad sostenible y partir de una propuesta metodol\uf3gica desarrollada como parte de un trabajo de maestr\ueda, esta ponencia presenta una propuesta de dise\uf1o aplicada al corredor Bol\uedvar, entre calle 44 San Juan y Calle, en el centro de Medell\uedn.The rise of vehicular mobility during the 20th century led to a progressive decline of pedestrian mobility and one of the primary activities of human beings: walking. However, conflicts generated by urban growth and environmental deterioration have raised questions about how we think and intervene in our cities, giving rise to a gradual shift in mobility paradigms. Today, pedestrian, and non-motorized mobility have reemerged as central topics for both public agendas and the intervention on urban space. This shift has brought into the debate a variety of reflections about spatial design and quality and the human experience of space. To demonstrate the importance of pedestrian environments as a key space for sustainable mobility practices and based on a methodological proposal developed as part of a master\u27s work, this paper presents a design proposal applied to Bol\uedvar corridor, between Calle 44 San Juan and Calle, in the center of Medell\uedn

Climate vulnerability, impacts and adaptation in Central and South America coastal areas

© 2019 Elsevier B.V. Low-Elevation Coastal Zones in Central and South America are exposed to climate-related hazards (sea-level rise, climate variability and storms) which threaten the assets (people, resources, ecosystems, infrastructure, and the services they provide), and are expected to increase due to climate change. A non-systematic review is presented focusing on vulnerability elements, impacts, constraints to adaptation, and their possible strategies. The analysis emphasises the Intergovernmental Panel on Climate Change Reasons for Concern (e.g., threatened systems, extreme events, aggregated impacts, and critical thresholds), particularly on sea-level rise, degradation of mangroves, and invasive alien species in Central and South America focusing on case studies from Uruguay and Venezuela. Despite recent advances in coastal adaptation planning in Central and South America, there is an adaptation deficit in the implementation of measures and strategies against climate-related hazards, such as sea-level rise. Adaptation constraints are linked with poverty, resource allocation, lack of political will, and lack of early warning systems for climate-related hazards. Non-structural adaptation measures such as community-based adaptation and ecosystem-based adaptation are not fully mainstreamed into national plans yet. Government-level initiatives (e.g. National Adaptation Programmes of Action) are being developed, but a few are already implemented. In addition to specific thematic measures, the implementation of non-structural approaches, National Adaptation Programmes of Action and early warning systems, based on the reasons for concern, should foster adaptive capacity in coastal areas

Companions of Bright Barred Shapley Ames Galaxies

Companion galaxy environment for a subset of 78 bright and nearby barred galaxies from the Shapley Ames Catalog is presented. Among spiral barred galaxies there are Seyfert galaxies, galaxies with circumnuclear structures, galaxies not associated with any large scale galaxy cloud structure, galaxies with peculiar disk morphology (crooked arms) and galaxies with normal disk morphology; the list includes all Hubble types. The companion galaxy list includes number of companion galaxies within 20 diameters (D25), their Hubble type and projected separation distance. Additionally, companion environment was searched for four known active spiral galaxies, three of them are Seyfert galaxies, namely, NGC 1068, NGC 1097, NGC 5548 and one is a starburst galaxy, M82. Among the results obtained it is noted that the only spiral barred galaxy classified as Sy 1 in our list has no companions within a projected distance of 20 diameters; 6 out of 10 Sy 2 bar galaxies have no companions within 10 diamters, 6 out of 10 Sy 2 galaxies have one or more companions at projected separation distances between 10 and 20 diameters; 6 out of 12 galaxies with circumnuclear structures have 2 or more companions within 20 diametersComment: Accepted for publication in the Astronomical Journal, 40 pages incl. 3 figure

The Chemical Evolution Carousel of Spiral Galaxies : Azimuthal Variations of Oxygen Abundance in NGC1365

19 pages, 13 figures. Accepted to ApJThe spatial distribution of oxygen in the interstellar medium of galaxies is the key to understanding how efficiently metals that are synthesized in massive stars can be redistributed across a galaxy. We present here a case study in the nearby spiral galaxy NGC1365 using 3D optical data obtained in the TYPHOON Program. We find systematic azimuthal variations of the HII region oxygen abundance imprinted on a negative radial gradient. The 0.2 dex azimuthal variations occur over a wide radial range of 0.3 to 0.7 R25 and peak at the two spiral arms in NGC1365. We show that the azimuthal variations can be explained by two physical processes: gas undergoes localized, sub-kpc scale self-enrichment when orbiting in the inter-arm region, and experiences efficient, kpc scale mixing-induced dilution when spiral density waves pass through. We construct a simple chemical evolution model to quantitatively test this picture and find that our toy model can reproduce the observations. This result suggests that the observed abundance variations in NGC1365 are a snapshot of the dynamical local enrichment of oxygen modulated by spiral-driven, periodic mixing and dilution.Peer reviewedFinal Published versio

Impact of Daily Thermocycles on Hatching Rhythms, Larval Performance and Sex Differentiation of Zebrafish

In the wild, water temperature cycles daily: it warms up after sunrise, and cools rapidly after sunset. Surprisingly, the impact of such daily thermocycles during the early development of fish remains neglected. We investigated the influence of constant vs daily thermocycles in zebrafish, from embryo development to sexual differentiation, by applying four temperature regimens: two constant (24°C and 28°C) and two daily thermocycles: 28:24°C, TC (thermophase coinciding with daytime, and cryophase coinciding with night-time) and 24:28°C, CT (opposite to TC) in a 12:12 h light:dark cycle (LD). Embryo development was temperature-dependent but enhanced at 28°C and TC. Hatching rhythms were diurnal (around 4 h after lights on), but temperature- and cycle-sensitive, since hatching occurred sooner at 28°C (48 hours post fertilization; hpf) while it was delayed at 24°C (96 hpf). Under TC, hatching occurred at 72 hpf, while under CT hatching displayed two peaks (at 70 hpf and 94 hpf). In constant light (LL) or darkness (DD), hatching rhythms persisted with tau close to 24 h, suggesting a clock-controlled "gating" mechanism. Under 28°C or TC, larvae showed the best performance (high growth and survival, and low malformations). The sex ratio was strongly influenced by temperature, as the proportion of females was higher in CT and TC (79 and 83% respectively), contrasting with 28°C and 24°C, which led to more males (83 and 76%). Ovarian aromatase (cyp19a) expression in females was highest in TC and CT (6.5 and 4.6 fold higher than at 28°C, respectively); while anti-müllerian hormone (amh) expression in males increased in testis at 24°C (3.6 fold higher compared to TC) and particularly at 28°C (14.3 fold increase). Taken together, these findings highlight the key role of environmental cycles during early development, which shaped the daily rhythms in fish embryo and larvae, and ultimately influenced sex differentiation