EVALUACIÓN A CORTO PLAZO DE LA BIOMETRÍA Y CRECIMIENTO DE LUTJANUS GUTTATUS, LUTJANUS PERU Y LUTJANUS ARGENTIVENTRIS, BÚCARO, PANAMÁ

The size and growth assessment of Lutjanus guttatus, L. peru, and L. argentiventris, captured by the artisanal fleet that disembarks in the community of Búcaro, Panama, for a period of six months, the size composition is described, the weight vs. height relationship, growth was estimated based on the monthly length structure, for which L?, catabolic coefficient k, the hypothetical age to for height 0, and the evaluation index of ? 'and the longevity A0.95, the von Bertalanffy equation was developed for each species and the analysis of the modal progression "VBGF". The length varied between 204 and 648 mm and the weight ranged between 85 and 3 373 g, in the three species, the relationship of these variables showed an isometric growth, the modal progression indicated two cohorts defined in L. guttatus, not so in the other species. The results are a baseline contribution for the development of the study of artisanal fishing biology in the Central American Pacific zone.Se realizó la evaluación de longitud y el crecimiento de Lutjanus guttatus, L. peru y L. argentiventris, capturados por la flota artesanal que desembarca en la comunidad de Búcaro, Panamá, por un período de seis meses, se describe la composición de tallas, la relación peso vs longitud total, se estimó el crecimiento basado en la estructura de tallas mensuales, para lo cual se describe L? , coeficiente catabólico k, la edad hipotética to para la longitud 0, además el índice de evaluación de ?’ y la longevidad A0,95, se desarrolló la ecuación de von Bertalanffy para cada especie y el análisis de la progresión modal “VBGF”. La longitud total varió entre 204 y 648 mm y el peso osciló entre 85 y 3 373 g, para las tres especies, la relación de estas variables mostró un crecimiento isométrico, la progresión modal indicó dos cohortes definidas de L. guttatus, no así en las otras especies. Los resultados son un aporte de línea base para el desarrollo del estudio de la biología pesquera artesanal de la zona del Pacífico centroamericano

Reproductive biology of spotted rose snapper Lutjanus guttatus (Teleostei: Lutjanidae) from Ensenada Búcaro, external border of Panama ecoregion

Se realizó un muestreo quincenal, por seis meses, de los desembarcos del pargo de la mancha (Lutjanus guttatus) en la comunidad de Búcaro, Panamá. Se recolectaron 237 individuos y se determinó sus variables morfométricas. Se seleccionaron 25 ejemplares para el análisis histológico de las gónadas. Se obtuvo un intervalo de talla entre 205 a 605 mm LT, y una proporción sexual que no difirió significativamente de la esperada 1M:1H. Se describen cuatro estadios de desarrollo gonadal en hembras y tres en machos. El índice gonadosomático y el factor de condición máximos en hembras fue de 1,67 en noviembre y de 1,24 en enero respectivamente, la talla de primera madurez sexual se estimó en 396,60 mm LT para hembras y 361,29 mm LT en machos. La información obtenida sugiere que la reproducción ocurre principalmente entre noviembre y enero.A biweekly sampling was carried out, for six months, of the landings of the spotted rose (Lutjanus guttatus) in the community of Búcaro, Panama. A total of 237 individuals was collected, and their morphometric variables were determined, 25 specimens were selected for the histological analysis of the gonads. A range of size 205 to 605 mm LT was obtained, the sex ratio was 1M: 1F. Four stages of gonadal development are described in females and three in males. Tre maximum values for the gonadosomatic index and the maximum condition factor in females were 1.67 in November and 1.24 in January respectively. The length at first sexual maturity was estimated at 396.60 mm LT for females and 361.29 mm LT for males. The information obtained suggests that reproduction occurs mainly between November and December. &nbsp

Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects

The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E$^{-2}$ shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E$^{-2}$ be able to explain the observations

A search for ultra-high-energy photons at the Pierre Auger Observatory exploiting air-shower universality

The Pierre Auger Observatory is the most sensitive detector to primary photons with energies above ∼0.2 EeV. It measures extensive air showers using a hybrid technique that combines a fluorescence detector (FD) with a ground array of particle detectors (SD). The signatures of a photon-induced air shower are a larger atmospheric depth at the shower maximum (X$_{max}$) and a steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced background. Using observables measured by the FD and SD, three photon searches in different energy bands are performed. In particular, between threshold energies of 1-10 EeV, a new analysis technique has been developed by combining the FD-based measurement of X$_{max}$ with the SD signal through a parameter related to its muon content, derived from the universality of the air showers. This technique has led to a better photon/hadron separation and, consequently, to a higher search sensitivity, resulting in a tighter upper limit than before. The outcome of this new analysis is presented here, along with previous results in the energy ranges below 1 EeV and above 10 EeV. From the data collected by the Pierre Auger Observatory in about 15 years of operation, the most stringent constraints on the fraction of photons in the cosmic flux are set over almost three decades in energy

Study on multi-ELVES in the Pierre Auger Observatory

Since 2013, the four sites of the Fluorescence Detector (FD) of the Pierre Auger Observatory record ELVES with a dedicated trigger. These UV light emissions are correlated to distant lightning strikes. The length of recorded traces has been increased from 100 μs (2013), to 300 μs (2014-16), to 900 μs (2017-present), to progressively extend the observation of the light emission towards the vertical of the causative lightning and beyond. A large fraction of the observed events shows double ELVES within the time window, and, in some cases, even more complex structures are observed. The nature of the multi-ELVES is not completely understood but may be related to the different types of lightning in which they are originated. For example, it is known that Narrow Bipolar Events can produce double ELVES, and Energetic In-cloud Pulses, occurring between the main negative and upper positive charge layer of clouds, can induce double and even quadruple ELVES in the ionosphere. This report shows the seasonal and daily dependence of the time gap, amplitude ratio, and correlation between the pulse widths of the peaks in a sample of 1000+ multi-ELVES events recorded during the period 2014-20. The events have been compared with data from other satellite and ground-based sensing devices to study the correlation of their properties with lightning observables such as altitude and polarity

Studies of the mass composition of cosmic rays and proton-proton interaction cross-sections at ultra-high energies with the Pierre Auger Observatory

In this work, we present an estimate of the cosmic-ray mass composition from the distributions of the depth of the shower maximum (Xmax) measured by the fluorescence detector of the Pierre Auger Observatory. We discuss the sensitivity of the mass composition measurements to the uncertainties in the properties of the hadronic interactions, particularly in the predictions of the particle interaction cross-sections. For this purpose, we adjust the fractions of cosmic-ray mass groups to fit the data with Xmax distributions from air shower simulations. We modify the proton-proton cross-sections at ultra-high energies, and the corresponding air shower simulations with rescaled nucleus-air cross-sections are obtained via Glauber theory. We compare the energy-dependent composition of ultra-high-energy cosmic rays obtained for the different extrapolations of the proton-proton cross-sections from low-energy accelerator data

Study of downward Terrestrial Gamma-ray Flashes with the surface detector of the Pierre Auger Observatory

The surface detector (SD) of the Pierre Auger Observatory, consisting of 1660 water-Cherenkov detectors (WCDs), covers 3000 km2 in the Argentinian pampa. Thanks to the high efficiency of WCDs in detecting gamma rays, it represents a unique instrument for studying downward Terrestrial Gamma-ray Flashes (TGFs) over a large area. Peculiar events, likely related to downward TGFs, were detected at the Auger Observatory. Their experimental signature and time evolution are very different from those of a shower produced by an ultrahigh-energy cosmic ray. They happen in coincidence with low thunderclouds and lightning, and their large deposited energy at the ground is compatible with that of a standard downward TGF with the source a few kilometers above the ground. A new trigger algorithm to increase the TGF-like event statistics was installed in the whole array. The study of the performance of the new trigger system during the lightning season is ongoing and will provide a handle to develop improved algorithms to implement in the Auger upgraded electronic boards. The available data sample, even if small, can give important clues about the TGF production models, in particular, the shape of WCD signals. Moreover, the SD allows us to observe more than one point in the TGF beam, providing information on the emission angle