Evaluación ecosistémica del golfo de Cádiz: análisis integral y descripción de procesos

Los modelos y análisis de ecosistemas son herramientas importantes que pueden ayudar a las partes interesadas a comprender sistemas complejos y evaluar cómo estos sistemas responden a los posibles cambios del ecosistema. En la presente tesis doctoral, ha sido investigado el estado del ecosistema del golfo de Cádiz (GoC) y la evolución temporal de sus recursos marinos utilizando un enfoque multidisciplinar, que ha combinado modelación y análisis de integración de datos. Los resultados resaltaron una serie de puntos relevantes para los ecosistemas costero y marino: el ecosistema del GoC en los últimos 20 años ha pasado por muchos cambios, desde la forma como le vemos, su explotación, así como las medidas de protección. En este sentido ese estudio aporta información inédita a través del desarrollo de un análisis integral del ecosistema del GoC, describiendo la evolución temporal del ecosistema de forma holística y conjunta, analizando los efectos naturales y antropogénicos en su principal zona de cría, el estuario del Río Guadalquivir, y, por último, caracterizando la distribución espacio-temporal de la comunidad zooplanctónica. Finalmente, el presente estudio ha identificado futuras líneas de investigación que podrán ayudar en el desarrollo ambiental y socioeconómico, y buscar maneras más eficaces para maximizar la equidad y la sostenibilidad de los recursos marinos

Simple Sonochemical Method to Optimize the Heating Efficiency of Magnetic Nanoparticles for Magnetic Fluid Hyperthermia

We developed a fast, single-step sonochemical strategy for the green manufacturing of magnetite (Fe3O4) magnetic nanoparticles (MNPs), using iron sulfate (FeSO4) as the sole source of iron and sodium hydroxide (Na(OH)) as the reducing agent in an aqueous medium. The designed methodology reduces the environmental impact of toxic chemical compounds and minimizes the infrastructure requirements and reaction times down to minutes. The Na(OH) concentration has been varied to optimize the final size and magnetic properties of the MNPs and to minimize the amount of corrosive byproducts of the reaction. The change in the starting FeSO4concentration (from 5.4 to 43.1 mM) changed the particle sizes from (20 ± 3) to (58 ± 8) nm. These magnetite MNPs are promising for biomedical applications due to their negative surface charge, good heating properties (˜324 ± 2 W/g), and low cytotoxic effects. These results indicate the potential of this controlled, easy, and rapid ultrasonic irradiation method to prepare nanomaterials with enhanced properties and good potential for use as magnetic hyperthermia agents

Application of the zero-range potential model to positron annihilation on molecules

In this paper we use a zero-range potential (ZRP) method to model positron interaction with molecules. This allows us to investigate the effect of molecular vibrations on positron-molecule annihilation using the van der Waals dimer Kr2 as an example. We also use the ZRP to explore positron binding to polyatomics and examine the dependence of the binding energy on the size of the molecule for alkanes. We find that a second bound state appears for a molecule with ten carbons, similar to recent experimental evidence for such a state emerging in alkanes with twelve carbons.Comment: 14 pages, 6 figures, to be published in Nuclear Instruments and Methods

Seasonal variation of zooplankton and environmental conditions along a transect in the Gulf of Cádiz

This study presents seasonal variation in the zooplankton composition of the Gulf of Cádiz was studied between 2001 and 2012. Samples were collected three times per year, in the spring, summer and autumn at three stations situated along a transect perpendicular to the coast. The total zooplankton abundance during the summer was higher than in the spring and autumn. Zooplankton community is characterized by a seasonal cycle mirroring similar cycles in the physical environment. Differences in community composition were also found along the transect, particularly between the coastal station, under the influence of the Guadalquivir River, and the outer station, characterized by oceanic conditions. This study is the first description of the seasonal and spatial variation of this marine component of the Gulf of Cádi

International politics must be considered together with climate and fisheries regulation as a driver of marine ecosystems

Seafood is an essential source of protein globally. As its demand continues to rise, balancing food security and the health of marine ecosystems has become a pressing challenge. Ecosystem-based fisheries management (EBFM) has been adopted by the European Union (EU) Common Fisheries Policy (CFP) to meet this challenge by ac- counting for the multiple interacting natural and socio-economic drivers. The CFP includes both the imple- mentation of regulatory measures to EU stocks and the establishment of bilateral fisheries agreements with neighbouring countries, known as sustainable fisheries partnership agreements (SFPAs). While the effects of fisheries management regulations are well acknowledged, the consequences of the SFPAs on EU ecosystems have been commonly overlooked. Here we investigate the development of the Gulf of Cadiz marine ecosystem over the last two decades and found evidence of the impact of both policy interventions. Our findings reveal the effec- tiveness of regulatory measures in reverting a progressively degrading ecosystem, characterised by high fishing pressure and dominance of opportunistic species, to a more stable configuration, characterised by higher biomass of small pelagics and top predators after 2005. Knock-on effects of the EU-Morocco SFPA and climate effects were detected before 2005, resulting in increased purse seine fishing effort, lower biomass of pelagic species and warmer temperatures. This southern EU marine ecosystem has been one of the latest to introduce regulations and is very exposed to fishery agreements with neighbouring Morocco. Our study highlights the importance of taking into consideration, not only the effects of in situ fisheries regulations but also the indirect implications of political agreements in the framework of EBFM.Marie Curie (re)Integration Grant (M.Ll., FP7-PEOPLE, ref: PERG05-GA-2009-247528), OCAL-DILEMA project (ref: CTM2014-59244-C3-2-R), CAPES Foundation and the Science without Borders fellowship program (ref: 99999.013763/2013- 00), EASME/ EMFF/2018/1.3.2.4/Lot2/SI2.818388-SC03En prensa6,86

Lepton Flavor Violation in the SUSY-GUT Models with Lopsided Mass Matrix

The tiny neutrino masses measured in the neutrino oscillation experiments can be naturally explained by the supersymmetric see-saw mechanism. If the supersymmetry breaking is mediated by gravity, the see-saw models may predict observable lepton flavor violating effects. In this work, we investigate the lepton flavor violating process $\mu\to e\gamma$ in the kind of neutrino mass models based on the idea of the ``lopsided'' form of the charged lepton mass matrix. The constraints set by the muon anomalous magnetic moment are taken into account. We find the present models generally predict a much larger branching ratio of $\mu\to e\gamma$ than the experimental limit. Conversely, this process may give strong constraint on the lepton flavor structure. Following this constraint we then find a new kind of the charged lepton mass matrix. The feature of the structure is that both the elements between the 2-3 and 1-3 generations are ``lopsided''. This structure produces a very small 1-3 mixing and a large 1-2 mixing in the charged lepton sector, which naturally leads to small $Br(\mu\to e\gamma)$ and the LMA solution for the solar neutrino problem.Comment: 24 pages, 8 figure

Emergence of quasi-metallic state in disordered 2D electron gas due to strong interactions

The interrelation between disorder and interactions in two dimensional electron liquid is studied beyond weak coupling perturbation theory. Strong repulsion significantly reduces the electronic density of states on the Fermi level. This makes the electron liquid more rigid and strongly suppresses elastic scattering off impurities. As a result the weak localization, although ultimately present at zero temperature and infinite sample size, is unobservable at experimentally accessible temperature at high enough densities. Therefore practically there exists a well defined metallic state. We study diffusion of electrons in this state and find that the diffusion pole is significantly modified due to "mixture" with static photons similar to the Anderson - Higgs mechanism in superconductivity. As a result several effects stemming from the long range nature of diffusion like the Aronov - Altshuler logarithmic corrections to conductivity are less pronounced.Comment: to appear in Phys. Rev.

Search for Rare and Forbidden Dilepton Decays of the D+, Ds, and D0 Charmed Mesons

We report the results of a search for flavor-changing neutral current, lepton-flavor violating, and lepton-number violating decays of D+, Ds, and D0 mesons (and their antiparticles) into modes containing muons and electrons. Using data from Fermilab charm hadroproduction experiment E791, we examine the pi,l,l and K,l,l decay modes of D+ and Ds and the l+l- decay modes of D0. No evidence for any of these decays is found. Therefore, we present branching-fraction upper limits at 90% confidence level for the 24 decay modes examined. Eight of these modes have no previously reported limits, and fourteen are reported with significant improvements over previously published results.Comment: 12 pages, 3 figures, LaTeX, elsart.cls, epsf.sty, amsmath.sty Submitted to Physics Letters