La deformabilidad del suelo "in situ". Un método para la interpretación conjunta de los ensayos de laboratorio y de campo

Los ensayos de laboratorio y de campo que permiten evaluar la defonnabilidad del terreno conducen generalmente a resultados poco acordes entre sí. La interpretación conjunta de los resultados de ambos tipos de ensayos es un procedimiento habitual para el establecimiento de leyes constitutivas tensióndeformación del suelo "in situ", con validez para estados tensionales variables dentro de límites determinados. El ensayo "in situ" estudiado en este caso (placa de carga) se reproduce de forma numérica utilizando un modelo de cálculo capaz de admitir la ley constitutiva establecida en el laboratorio (modelo hiperbólico) y, posteriormente, se comparan sus resultados con los del ensayo real. Para simular el ensayo de carga se ha desarrollado un modelo simplificado que permite tener en cuenta la respuesta heterogénea del suelo debida a la existencia de presiones de confinamiento variables y la no linealidad entre tensiones y deformaciones para un confinamiento dado. El modelo simplificado se ha desarrollado en lenguaje FORTRAN ("PLACAR"), consiguiéndose un programa de utilización sencilla y coste reducido. Los resultados se han contrastado con un modelo de elementos finitos. Finalmente, se incluyen dos ejemplos de aplicación práctica. En el primero la interpretación conjunta resulta eficaz y se analiza la extrapolación de los resultados a las dimensiones de las cimentaciones reales. En cambio, en el segundo ejemplo la interpretación no tiene utilidad práctica.Peer Reviewe

Adicción al deporte: el peligro de la sobredosis de ejercicio

La práctica deportiva forma parte del estilo de vida de los seres humanos postmodernos, pudiendo convertirse en una obsesión cuando su uso es excesivo, continuo, constante e intenso, pudiendo dar lugar a la adicción o dependencia al ejercicio. Actualmente son pocos los estudios e investigaciones hechos al respecto, por ello nuestro objetivo es analizar el estado de la cuestión, sus características psicológicas y psicopatológicas, y elaborar un cuestionario que permita evaluar la adicción al ejercicio, así como establecer su fiabilidad y validez para su detección y manejo clínico. Tras la elaboración del cuestionario, SAS, hemos pretendido observar cómo se manifiesta la adicción a nivel físico, psicológico y social. En este artículo presentamos los primeros resultados analizados tras un estudio exploratorio piloto a una muestra pequeña, N=33, compuesta por 16 mujeres y 17 hombres, que contestaron de forma voluntaria el cuestionario, compuesto por 40 ítems sencillos de respuesta dicotómica, (NO; SI). Aunque es una muestra limitada, la fiabilidad de dicho cuestionario es buena, con un Alpha de Cronbach superior a 0.8. Algunos de los enunciados del mismo han resultado ser muy específicos para la detección de la adicción, y asimismo, la edad y las horas dedicadas a la práctica de ejercicio físico tienen especial relevancia. Como conclusión se propone la primera escala española (SAS) para la detección de la adicción o dependencia al deporte, cuya fiabilidad y validez será analizada en estudios posteriores

GROWTH AND SURVIVAL OF 0 + ABFT Thunnus thynnus FINGERLINGS KEPT IN TANKS

This article shows the most relevant results obtained between August 2017 and October 2018 with two batches of 0+ tunas: cultured tunas (CT) born in the IEO facilities in June 2017 and wild tunas (WT) captured in Mazarron Bay in September 2017. Fertilized ABFT eggs were collected from cages owned by PisciAlba and obtained larvae were cultured in IEO facilities. At the end of July 2017, 500 fingerlings (CT, 2 g average weight) were move to ICRA facilities on 29th July and placed in a 1000 m3 tank. At the end of September 2017 mean weight were 350 gr. In that moment, a total of 68 0+ ABFT fingerlings (WT, 414 g mean weight), were captured from the Mazarron Bay and placed in a 3500 m3 tank in ICRA. From this moment temperature ranged between 18 and 27ºC, and feeding consisted in bait, mainly Sardinella aurita and Scomber scombrus, but also Scomber japonicus, Engraulis encrasicolus and Clupea harengus. During November 2017, mortality increased in CT without any symptoms of infectious disease. 80 healthier CT were then moved to a greater tank (2500 m3 ) and in March 2018, when completely recovered, they were placed together with WT and both batches were cultured in the same tank up to now. During the 13 months period mortality observed in CT was high (close to 85%) while mortality in WT was lower than 15%. Growth was also slightly faster in WT. Feeding intake ranged during the whole period between 3 and 26%, and feeding conversion rate estimated was close to 12. At the end of October 2018 mean weight of population was 11 kg

ESTABLISHING AN ATLANTIC BLUEFIN TUNA (Thunnus thynnus) BROODSTOCK

The Spanish Institute of Oceanography owns a facility to reproduce Atlantic bluefin tuna (ABFT). This facility was built in 2015 and in August 2017, some fingerlings born in captivity were moved to this installation, and some wild tunas were added two months later. In November 2019, this batch consists in 69 2+ ABFT weighting 28 kg. Hopefully they can reach 40 kg at the beginning of June and spawn by the first time. Fertilized ABFT eggs were collected from cages owned by PisciAlba and obtained larvae were cultured in IEO facilities. At the end of July 2017, some fingerlings (Cultured batch –CB-, 2 gr mean weight) were move to ICRA facilities and placed in a 1000 m3 tank. At the end of September 2017 a total of 68 0+ ABFT fingerlings (Wild batch –WB-, 414 g mean weight), were captured from the Mazarron Bay and placed in another tank in ICRA. 4 months later, 81 tunas coming from both batches were weighted (2.5 kg mean weight), tagged and place together in a 3500 m3 tank. During all the time, temperature ranged between 17 and 27ºC, and food consisted in bait, mainly, Scomber scombrus (47% of the total food) and Clupea harengus (25%) but also Sardinella aurita, Engraulis encrasicolus and Scomber japonicus (11, 10 and 7% respectively). From February 2018 to November 2019, mortality has been 16.9% (10.9% in WB and 28.6% in CB) and tunas have grown to reach an average of 28 kg. Biomass in this moment is 1930 kg, which means a density of 0.55 kg/m3 . Feeding intake was high during the first six months (when tunas were smaller than 2.5 kg), but after this moment it has ranged between 2.5 and 7%, decreasing with the size of tunas and increasing slightly with higher temperatures (circles). Feeding conversion rate was quite stable during the period, averaging 13.8. According to forecast, at the end of next spring, average weight will be about 40 kg, with about 15 tunas greater than 50 kg. This means that they will be able to reproduce next summer if gonadal maturation develops properly

First results on ongrowing of hatchery reared Atlantic bluefin tuna, Thunnus thynnus, kept in sea cages

Bluefin tuna (ABFT) fingerlings born in captivity were raised during 15 months in sea cages. ABFT were fed with raw fish, and they grew during this period from 4 gr to 8 kg. Mortality rate was great, mainly during the first three months. This is the first experience of ongrowing ABFT born in captivity.EU (SELFDOTT), Caladeros del Mediterráneo, S.A. Instituto Español de Oceanografí

The effect of different short pulse feeding regimes on growth and survival of Atlantic bonito larvae Sarda sarda

One of the most easily manipulated variables in fish larval culture is the photoperiod. Long light photoperiod regimes are commonly used to enhance growth in commercial species. However, for species with a piscivorous larval period, as the Atlantic bonito (Sarda sarda), long time exposure to light could lead to a lower survival through aggressive behavior and cannibalism. One alternative could be modifications of the light and dark cycles during the photophase. These modifications can result in short pulse feeding regimes since bonito larvae fill up their stomach completely during light hours but do not feed in darkness. Little is known about how such intermittent feeding regimes affect growth and survival in fish. In this study, we tried different alternating and continuous light regimes during the culture of bonito larvae to identify the best regime that maximizes growth and survival.Fertilized eggs of Atlantic bonito were obtained from different spontaneous spawning events by a captive broodstock at the Spanish Institute of Oceanography (IEO) in Mazarrón. Bonito larvae 8 days post hatch (dph) were reared in 150 l tanks equipped with a lid that was used to cover and uncover the tanks to manipulate the hours of light and therefore pulse feeding regimes. Bonito larvae were always fed with yolk sac seabream larvae ad libitum. A total of three experiments were conducted. In all, a continuous dark period of 7.5hours was maintained from 24:00 to 7:30. All light regimes had a total of 9 light hours except for one that had 15hours of light (15L:9D). In the first experiment, light regimes provided alternating light and dark conditions of either 1.5, 3 or 4.5hours from 7:30 to 24:00). In the second experiment, the 3hours alternating light regime was compared to two continuous regimes of 15hours of light (15L:9D) and 9hours of light (9L:15D). These two experiments were conducted at the same temperature, 24.7±0.4°C. The third experiment was identical to the second experiment but at colder temperatures, 21.4±0.45°C. All regimes had 3 replicates. 10 larvae were sub-sampled 3 days after the experiments began and were ended after 6 days when all larvae were sampled. Due to slower growth, the third experiment ended after 9 days. The larvae were measured in standard length and individual dry weights were calculated. Larvae were counted in the tanks every 3 days to estimate survivorship. Final larval sizes in the alternating light regimes were larger in the 3hours than those obtained in the 1.5 and 4.5hours (first experiment, Fig. 1a, Tukey test p0.01). The 3hours alternating light regime yielded the largest larval sizes at the end of the experiment compared to the other alternating regimes. Final sizes at the 3hours regime were larger than those obtained under the 9L:15D continuous light regime at both temperatures. The time to satiation and the elapsed time to evacuate food totally from the gut in a similar species is about 3-4hours (Young and Davis, 1990). Our results suggest that a better strategy for bonito larvae growth is to fill their stomach more than once per day followed by a resting period when food is being digested. However, no effect was observed in terms of survival, possibly due to high abundance of larval prey. Changes in the light regime that result in pulse feeding can be a good strategy to increase growth in larval cultures when fitting well the evacuation and satiation rates

Técnicas de electrónica de potencia para el electroaturdimiento y electrosacrificio, en el sector del atún rojo

Las técnicas de electropesca utilizadas en agua dulce han sido adaptadas a la explotación industrial de la pesca en agua salada de especies como el atún rojo. Por desgracia, como consecuencia de las descargas eléctricas aplicadas, a través de un arpón, se producen daños en la espina que disminuyen la calidad del producto. Se describe aquí un proyecto que aborda el desarrollo de un convertidor electrónico de potencia, versátil y que permite estudiar diferentes formas de onda y su efecto sobre la calidad del producto.Ginés Méndez España S.L

Effects of offshore wind farms operational noise on bluefin tuna behaviour

The number of offshore wind farms is growing up quickly in the lasts years. Several studies about its environmental acoustic impacts have been developed at the same time the industry expands, most of them related to the high level impulsive noise produced during the pile diving process associated to the construction stage. Nevertheless, the study of the impact of the operational noise of turbines is very limited. In this paper we investigate the behavioural response of Bluefin tuna when exposed to the operation noise of a turbine. We analysed tuna reaction in terms of three parameters: depth of the school, swimming pattern and changes in the swimming direction. The experiment was developedin a fixed commercial tuna cage in the Mediterranean Sea. The usual behaviour of Bluefin tuna in captivity conditions was previously analysed using a continuous monitorization. Variations in depth were observed when feeding boat approaches, which could be interpreted as a consequence of the acoustical stimulus. The turbine noise was acoustically characterized, and reproduced using a broad-band underwater source. To monitor tuna behaviour two echosounders and a video system were simultaneously used. When exposed to short duration noise tuna behaviour does not exhibit clear disturbances. Nevertheless, with long duration emission tuna reacted: school reduced the radio of thecircular swimming region, moved up to the surface and some individuals were disorientated. Tuna seems to be habituated after several repetitions is short time.Proyecto AZIMUT. This work was financially support from Spanish Government by grant AP2009-4459. We thank both personal and material facilities provided by Grup Balfegó and Nuevo Tomás y Carmen crew

Histogenesis and cell differentiation in the retina of Thunnus thynnus: a morphological and immunohistochemical study

This study examines the anatomical development of the visual system of Atlantic bluefin tuna, Thunnus thynnus, during the first 15 days of life at histological level, with emphasis in the immunohistochemical characterization of different cell types. As an altricial fish species, the retina was not developed at hatching. The appearance of eye pigmentation and the transformation of the retina from an undifferentiated neuroblastic layer into a laminated structure occurred during the first two days of life. At 16 days after hatching (DAH), the ganglion cells were arranged in a single row in the central region of the retina and the outer segments of the photoreceptors were morphologically developed. Furthermore, at this age, all the retinal cell types were immunohistochemically characterized. The presence of ganglion cell axons was confirmed with the TUJ1 antibody and the existence of functional synapses in the plexiform layers with antibodies against SV2. Cone opsins were immunostained with antibodies against visinin and CERN-922 immunoreactive rods were also identified. Different subpopulations of amacrine cells were immunostained with antibodies against αTH and PV. Highly GS-immunoreactive Müller cells were also detected at this age. These observations suggested that the T. thynnus retina was fully functional at the end of the second week of life. Basic studies on early morphology of the visual system and larval behaviour are necessary to support applied research on larval rearing. Furthermore, they may have implications for understanding larval ecology in the wild.Versión del edito

Preliminary trials on the development of electroslaughtering and electrostunning techniques for bluefin tuna Thunnus thynnus (L., 1758) reared in floating cages

Preliminary results are presented from an ongoing study concerning the relationship between the type of electrical waves used to slaughter bluefin tuna Thunnus thynnus (L., 1758) ongrown in floating cages, and damage to the dorsal column and fish meat, which reduces the fish's commercial value on the Japanese market. Our results indicate that varying the waves' characteristics can reduce those undesirable effects, making this technique the most suitable for bluefin tuna slaughtering, in order to obtain superior meat quality.Se presentan los resultados preliminares del estudio que se lleva a cabo sobre la relación existente entre el tipo de onda eléctrica utilizada para el electrosacrificio del atún rojo Thunnus thynnus (L., 1758), engordado en jaulas flotantes, y los daños producidos en la espina dorsal y la carne de los ejemplares de esta especie, que reducen su valor comercial en el mercado japonés. Se ha observado que se puede mitigar estos efectos indeseados variando las características de las ondas empleadas, haciendo de esta técnica la más apropiada en el sacrificio del atún para obtener una carne de calidad superior.Instituto Español de OceanografíaVersión del editor