Ensayo de marcado-recaptura para la estimación de tasas de crecimiento en peces arrecifales del género acanthurus en el caribe colombiano

Se empleó la técnica de marcado y recaptura en peces marinos para establecer tasas de crecimiento mensual y relaciones longitud- peso para las tres especies del género Acanthurus, durante las épocas de sequía (surgencia) y lluvias en el área de Punta de Betín, Santa Marta, Colombia.The mark and recapture technique was used with the three species of the genus Acanthurus in order to establish growth rates and length-weight relationships during the upwelling and rainy seasons in the area of Punta de Betín, Santa Marta, Colombia

On the puzzling high-energy pulsations of the energetic radio-quiet γ\gamma-ray pulsar J1813−-1246

We have analyzed the new deep {\it XMM-Newton} and {\it Chandra} observations of the energetic radio-quiet pulsar J1813$-$1246. The X-ray spectrum is non-thermal, very hard and absorbed. Based on spectral considerations, we propose that J1813 is located at a distance further than 2.5 kpc. J1813 is highly pulsed in the X-ray domain, with a light curve characterized by two sharp, asymmetrical peaks, separated by 0.5 in phase. We detected no significant X-ray spectral changes during the pulsar phase. We extended the available {\it Fermi} ephemeris to five years. We found two glitches. The $\gamma$-ray lightcurve is characterized by two peaks, separated by 0.5 in phase, with a bridge in between and no off-pulse emission. The spectrum shows clear evolution in phase, being softer at the peaks and hardenning towards the bridge. The X-ray peaks lag the $\gamma$-ray ones by 0.25 in phase. We found a hint of detection in the 30-500 keV band with {\it INTEGRAL} IBIS/ISGRI, that is consistent with the extrapolation of both the soft X-ray and $\gamma$-ray emission of J1813. The peculiar X and $\gamma$-ray phasing suggests a singular emission geometry. We discuss some possibilities within the current pulsar emission models. Finally, we develop an alternative geometrical model where the X-ray emission comes from polar cap pair cascades.Comment: 26 pages, 10 figures, 2 tables, submitted to Astrophysical Journa

Distribución geográfica y estado de conservación de los peces sierra Pristis spp (Pristiformes: Pristidae) en el Caribe sur

The former presence of sawfishes (Pristis spp) is confirmed for the southern Caribbean Sea from the coasts of Colombia and Venezuela, based on review of eleven rostral saws exhibited in businesses, museums and private collections, as well as bibliographic references, photographs and surveys to detect sightings or captures in both countries. We determined that Pristis pristis and Pristis pectinata were present in the southern Caribbean coasts of Colombia and Venezuela, but that they are now probably locally extinct.Se confirma la presencia en el pasado de las especies de pez sierra (Pristis spp) en el mar Caribe de Colombia y Venezuela, a partir de la revisión de once extensiones rostrales exhibidas en establecimientos, museos y colecciones de particulares, así como la consulta bibliográfica, encuestas y el examen de material fotográfico disponible sobre avistamientos o capturas realizadas en ambos países. Se determinó que las especies presentes en el Caribe de Colombia y Venezuela eran Pristis pristis y Pristis pectinata, las cuales en la actualidad se encuentran probablemente extintas localmente

Extended search for supernovalike neutrinos in NOvA coincident with LIGO/Virgo detections

A search is performed for supernovalike neutrino interactions coincident with 76 gravitational wave events detected by the LIGO/Virgo Collaboration. For 40 of these events, full readout of the time around the gravitational wave is available from the NOvA Far Detector. For these events, we set limits on the fluence of the sum of all neutrino flavors of F[removed]29(50) kpc at 90% C.L. Weaker limits are set for other gravitational wave events with partial Far Detector data and/or Near Detector data. © 2021 authors. Published by the American Physical Society

Search for Active-Sterile Antineutrino Mixing Using Neutral-Current Interactions with the NOvA Experiment

This Letter reports results from the first long-baseline search for sterile antineutrinos mixing in an accelerator-based antineutrino-dominated beam. The rate of neutral-current interactions in the two NOvA detectors, at distances of 1 and 810 km from the beam source, is analyzed using an exposure of 12.51×1020 protons-on-target from the NuMI beam at Fermilab running in antineutrino mode. A total of 121 of neutral-current candidates are observed at the far detector, compared to a prediction of 122±11(stat.)±15(syst.) assuming mixing only between three active flavors. No evidence for ν¯μ→ν¯s oscillation is observed. Interpreting this result within a 3+1 model, constraints are placed on the mixing angles θ24<25° and θ34<32° at the 90% C.L. for 0.05 eV2≤Δm412≤0.5 eV2, the range of mass splittings that produces no significant oscillations at the near detector. These are the first 3+1 confidence limits set using long-baseline accelerator antineutrinos. © 2021 authors. Published by the American Physical Society

Star Formation in Extreme Environments: The Effects of Cosmic Rays and Mechanical Heating

Context: Molecular data of extreme environments, such as Arp 220, but also NGC 253, show evidence for extremely high cosmic ray (CR) rates (10^3-10^4 * Milky Way) and mechanical heating from supernova driven turbulence. Aims: The consequences of high CR rates and mechanical heating on the chemistry in clouds are explored. Methods: PDR model predictions are made for low, n=10^3, and high, n=10^5.5 cm^-3, density clouds using well-tested chemistry and radiation transfer codes. Column densities of relevant species are discussed, and special attention is given to water related species. Fluxes are shown for fine-structure lines of O, C+, C, and N+, and molecular lines of CO, HCN, HNC, and HCO+. A comparison is made to an X-ray dominated region model. Results: Fine-structure lines of [CII], [CI], and [OI] are remarkably similar for different mechanical heating and CR rates, when already exposed to large amounts of UV. HCN and H2O abundances are boosted for very high mechanical heating rates, while ionized species are relatively unaffected. OH+ and H2O+ are enhanced for very high CR rates zeta > 5 * 10^-14 s^-1. A combination of OH+, OH, H2O+, H2O, and H3O+ trace the CR rates, and are able to distinguish between enhanced cosmic rays and X-rays.Comment: 13 pages, 8 figures, A&A accepte

Dispersión de metales pesados en los sedimentos fluviales del cauce alto del río Huerva (Zaragoza, España)

In this paper, the methodology of geochemical prospecting has been applied to the study of the scattering of cadmium, lead, cooper and zinc in the upper part of the Huerva river (Iberian Range, Spain). With this purpose two hundred and eleven samples of river sediments were collected along the upper part of the river. The analytical data, after being statistically processed, were interpreted with the aim of approaching to the main features of the models of scattering and to infer the main anomalous sources of these heavy metals to the channel. The results of this study prove the existence of multiple, complex sources, with the remarcable presence of sources related to the human presence and activity. However, the system seems to have a good ability to depurate itself.En este trabajo se ha aplicado la metodología de la prospección geoquímica al estudio y caracterización de los modelos de dispersión de cuatro metales pesados (cadmio, plomo, cobre y zinc) en el cauce alto del río Huerva (Cordillera Ibérica, España). Con este propósito se recogieron y analizaron doscientas once muestras de sedimento a lo largo de la zona de cabecera de este río. Los resultados analíticos obtenidos, tras recibir un tratamiento estadístico clásico, fueron interpretados para describir las características fundamentales de sus modelos de dispersión y, finalmente, identificar las fuentes principales de aporte anómalo de estos elementos al cauce del río Huerva. Las observaciones realizadas muestran la existencia de fuentes de aporte múltiples y complejas, entre las que destacan las relacionadas con la presencia y actividad antrópica. Sin embargo, el sistema parece poseer una buena capacidad de autodepuración natural para el cadmio, el plomo, el cobre y el zinc

Phenomenology of Quantum Gravity and its Possible Role in Neutrino Anomalies

New phenomenological models of Quantum Gravity have suggested that a Lorentz-Invariant discrete spacetime structure may become manifest through a nonstandard coupling of matter fields and spacetime curvature. On the other hand, there is strong experimental evidence suggesting that neutrino oscillations cannot be described by simply considering neutrinos as massive particles. In this manuscript we motivate and construct one particular phenomenological model of Quantum Gravity that could account for the so-called neutrino anomalies.Comment: For the proceedings of "Relativity and Gravitation: 100 Years after Einstein in Prague" (June 2012, Prague

Very-high energy gamma-ray astronomy: A 23-year success story in high-energy astroparticle physics

Very-high energy (VHE) gamma quanta contribute only a minuscule fraction - below one per million - to the flux of cosmic rays. Nevertheless, being neutral particles they are currently the best "messengers" of processes from the relativistic/ultra-relativistic Universe because they can be extrapolated back to their origin. The window of VHE gamma rays was opened only in 1989 by the Whipple collaboration, reporting the observation of TeV gamma rays from the Crab nebula. After a slow start, this new field of research is now rapidly expanding with the discovery of more than 150 VHE gamma-ray emitting sources. Progress is intimately related with the steady improvement of detectors and rapidly increasing computing power. We give an overview of the early attempts before and around 1989 and the progress after the pioneering work of the Whipple collaboration. The main focus of this article is on the development of experimental techniques for Earth-bound gamma-ray detectors; consequently, more emphasis is given to those experiments that made an initial breakthrough rather than to the successors which often had and have a similar (sometimes even higher) scientific output as the pioneering experiments. The considered energy threshold is about 30 GeV. At lower energies, observations can presently only be performed with balloon or satellite-borne detectors. Irrespective of the stormy experimental progress, the success story could not have been called a success story without a broad scientific output. Therefore we conclude this article with a summary of the scientific rationales and main results achieved over the last two decades.Comment: 45 pages, 38 figures, review prepared for EPJ-H special issue "Cosmic rays, gamma rays and neutrinos: A survey of 100 years of research