Effect of type of food and culture density on growth and lipid composition of Seriola dumerili juveniles

The aim of this study was to determine the effect of three different types of food and two stocking densities on growth, survival and lipid composition of muscle and liver of Seriola dumerili juveniles. Juvenile of S. dumerili were randomly distributed in groups of 15 fish/tank (low stocking density, LD) and groups of 25 fish/tank (high stocking density, HD) and fed with three different types of food: commercial pellets for Sparidae (SP), commercial pellets for S. dumerili (SE) and frozen Mackerel (MA). Samples of muscle and liver were taken for lipid analysis at the end of trial (86 days). Fish fed with SP showed growth significantly lower than the groups fed with SE and MA for both stocking densities. Higher survival rates was observed in fish fed diet SE and MA held at LD. Lipid composition analyses revealed important differences between fish fed with different diets but no difference between groups with different stocking density were detected. Total lipid content in muscle and liver from fish fed with SE was very much higher than in fish fed with SP and MA, which was reflected in higher tryglicerides and lower cholesterol contents. The fatty acid composition of tissues clearly reflected the composition of the diet supplied. The groups fed with MA presented the highest proportion of docosahexaenoic acid (DHA), arachidonic acid (ARA) and the lower amounts of eicosapentaenoic acid (EPA). In contrast, fish fed with SE presented the lower amounts of ARA and DHA and higher content in 18:2n-6 specifically in the liver. In consequence, fish fed with MA presented a higher DHA/EPA ratio and a lower EPA/AA ratio in both tissues while the opposite was observed in group SE. These preliminary results indicate that SE diet allows get better performance than SP diet obtaining growth and survival rates comparable to fish fed with MA, although with a higher lipid deposition in tissues

The Dynamical Environment of Dawn at Vesta

Dawn is the first NASA mission to operate in the vicinity of the two most massive asteroids in the main belt, Ceres and Vesta. This double-rendezvous mission is enabled by the use of low-thrust solar electric propulsion. Dawn will arrive at Vesta in 2011 and will operate in its vicinity for approximately one year. Vesta's mass and non-spherical shape, coupled with its rotational period, presents very interesting challenges to a spacecraft that depends principally upon low-thrust propulsion for trajectory-changing maneuvers. The details of Vesta's high-order gravitational terms will not be determined until after Dawn's arrival at Vesta, but it is clear that their effect on Dawn operations creates the most complex operational environment for a NASA mission to date. Gravitational perturbations give rise to oscillations in Dawn's orbital radius, and it is found that trapping of the spacecraft is possible near the 1:1 resonance between Dawn's orbital period and Vesta's rotational period, located approximately between 520 and 580 km orbital radius.This resonant trapping can be escaped by thrusting at the appropriate orbital phase. Having passed through the 1:1 resonance, gravitational perturbations ultimately limit the minimum radius for low-altitude operations to about 400 km,in order to safely prevent surface impact. The lowest practical orbit is desirable in order to maximize signal-to-noise and spatial resolution of the Gamma-Ray and Neutron Detector and to provide the highest spatial resolution observations by Dawn's Framing Camera and Visible InfraRed mapping spectrometer. Dawn dynamical behavior is modeled in the context of a wide range of Vesta gravity models. Many of these models are distinguishable during Dawn's High Altitude Mapping Orbit and the remainder are resolved during Dawn's Low Altitude Mapping Orbit, providing insight into Vesta's interior structure.Comment: Corrected normalization coefficients; updated table text and reference

Preliminary Results on Light Conditions Manipulation in Octopus vulgaris (Cuvier, 1797) Paralarval Rearing

High paralarvae mortality is a major bottleneck currently hindering the control over the lifecycle of common octopus (Octopus vulgaris Cuvier, 1797). It is believed that this problem might be related to either zoo-technical and/or nutritional aspects. The present paper is focused on the study of different zoo-technical aspects related to light conditions on the rearing of paralarvae, including the effects of polarization in prey ingestion, the use of a blue filter to simulate natural conditions, and the use of focused light to avoid reflections of the rearing tank’s walls. In the first experiment, O. vulgaris paralarvae ingestion of Artemia sp. and copepods (Tisbe sp.) was assessed under either normal or polarized light. In the second experiment, the effect of a blue filter with natural light or focused artificial light on growth and mortality was assessed over 15 days of rearing. Ingestion rate was not influenced by light polarization. Nonetheless, a significantly higher ingestion of Artemia sp. with respect to copepods was observed. The blue filter promoted the use of natural light conditions in Octopus paralarval culture, while focused light reduced the collision of the paralarvae against the walls. However, no significant differences were found in paralarval growth nor survivalEn prens

Aperiodicity in one-way Markov cycles and repeat times of large earthquakes in faults

A common use of Markov Chains is the simulation of the seismic cycle in a fault, i.e. as a renewal model for the repetition of its characteristic earthquakes. This representation is consistent with Reid's elastic rebound theory. Here it is proved that in {\it any} one-way Markov cycle, the aperiodicity of the corresponding distribution of cycle lengths is always lower than one. This fact concurs with observations of large earthquakes in faults all over the world

Mapping Vesta: First Results from Dawn’s Survey Orbit

The geologic objectives of the Dawn Mission [1] are to derive Vesta’s shape, map the surface geology, understand the geological context and contribute to the determination of the asteroids’ origin and evolution.Geomorphology and distribution of surface features will provide evidence for impact cratering, tectonic activity, volcanism, and regolith processes. Spectral measurements of the surface will provide evidence of the compositional characteristics of geological units. Age information, as derived from crater sizefrequency distributions, provides the stratigraphic context for the structural and compositional mapping results, thus revealing the geologic history of Vesta. We present here the first results of the Dawn mission from data collected during the approach to Vesta, and its first discrete orbit phase – the Survey Orbit, which lasts 21 days after the spacecraft had established a circular polar orbit at a radius of ~3000 km with a beta angle of 10°-15°

The Kuiper Belt and Other Debris Disks

We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade

Un meta-análisis sobre el crecimiento de las paralarvas de pulpo común (Octopus vulgaris) alimentadas con diferentes presas vivas

El objetivo del presente estudio fue comparar el efecto de la alimentación con diferentes presas vivas (Artemia y zoeas de crustáceos) y/o Artemia enriquecida, sobre el crecimiento de paralarvas de pulpo común (Octopus vulgaris) a través de un meta-análisis. Se usaron un total de 26 ensayos independientes para analizar las diferencias en crecimiento entre: (i) zoeas de crustáceos vs Artemia, (ii) diferentes especies de crustáceos y (iii) Artemia enriquecida con fosfolípidos marinos vs otros enriquecedores de Artemia. Se observó un mejor crecimiento de las paralarvas alimentadas con zoeas de crustáceos vs Artemia. Sin embargo, no todas las zoeas mostraron los mismos resultados, dada la alta variabilidad observada con el género Grapsus que impidió que se pudieran apreciar diferencias respecto a la Artemia usada como control. Finalmente, el enriquecimiento de Artemia con fosfolípidos marinos mejoró el crecimiento de las paralarvas, lo cual podría estar relacionado con el incremento en los niveles del ácido docosahexaenoico ((DHA, 22:6n-3) y de los lípidos polares en Artemia

Study of Z → llγ decays at √s = 8 TeV with the ATLAS detector

This paper presents a study of Z → llγ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb−1 collected at a centre-ofmass energy √s = 8 TeV. Integrated fiducial cross-sections together with normalised differential fiducial cross-sections, sensitive to the kinematics of final-state QED radiation, are obtained. The results are found to be in agreement with stateof-the-art predictions for final-state QED radiation. First measurements of Z → llγ γ decays are also reported

Search for leptoquark pair production decaying into te−te¯ + or tμ−t¯μ+ in multi-lepton final states in pp collisions at √s = 13 TeV with the ATLAS detector

A search for leptoquark pair production decaying into te−te¯ + or tμ−t¯μ+ in final states with multiple leptons is presented. The search is based on a dataset of pp collisions at √s = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. Four signal regions, with the requirement of at least three light leptons (electron or muon) and at least two jets out of which at least one jet is identified as coming from a b-hadron, are considered based on the number of leptons of a given flavour. The main background processes are estimated using dedicated control regions in a simultaneous fit with the signal regions to data. No excess above the Standard Model background prediction is observed and 95% confidence level limits on the production cross section times branching ratio are derived as a function of the leptoquark mass. Under the assumption of exclusive decays into te− (tμ−), the corresponding lower limit on the scalar mixed-generation leptoquark mass mLQd mix is at 1.58 (1.59) TeV and on the vector leptoquark mass mU˜1 at 1.67 (1.67) TeV in the minimal coupling scenario and at 1.95 (1.95) TeV in the Yang–Mills scenario