Understanding biological invasions : an experimental study with "Carpobrotus edulis"

[Resumen] Las invasiones biológicas suponen una de las mayores amenazas para la conservación de la biodiversidad a nivel global. Durante los últimos años han sido muchos los trabajos que se han dirigido a intentar conocer los atributos que provocan que una planta se convierta en un invasor agresivo. La plasticidad fenotípica, capacidad de los individuos de ajustar sus respuestas morfológicas y fisiológicas para adaptarse al ambiente, podría ser un atributo clave para entender los procesos de invasión. En este experimento utilizamos individuos de Carpobrotus edulis, una invasora muy agresiva, y Carpobrotus acinaciformis, especie exótica considerada menos agresiva, para comparar su plasticidad en términos de distribución de recursos ante la presencia de distintos niveles de nutrientes. Nuestro trabajo muestra que existen diferencias significativas en la cantidad de raíz producida por C. edulis y C. acinaciformis en función del contenido de nutrientes del suelo, con C. edulis mostrando una mayor plasticidad para este carácter. Este resultado parece apoyar la idea de que la plasticidad fenotípica podría contribuir al éxito de algunas especie invasoras.[Resumo] As invasións biolóxicas supoñen unha das maiores ameazas para a conservación da biodiversidade a nivel global. Durante os últimos anos, moitos traballos tentaron descubrir os atributos que fan que unha planta se converta nun invasor agresivo. A plasticidade fenotípica, capacidade dos individuos da axustar as súas respostas morfolóxicas e fisiolóxicas para adaptarse ó ambiente, podería ser un atributo clave para comprender os procesos de invasión. Neste experimento utilizamos individuos de Carpobrotus edulis, unha invasora moi agresiva, e Carpobrotus acinaciformis, especie exótica considerada coma menos agresiva, para Página 2 de 23 comparar a súa plasticidade atendendo á distribución de recursos da planta en función da presencia de distintos niveis de nutrientes. O noso traballo mostra que existen diferencias significativas na cantidade de raíz producida por C.edulis e C.acinaciformis en función do contido de nutrintes do solo, mostrando C.edulis unha maior plasticidade para este caracter. Iste resultado parece apoiar a idea de que a plasticidade fenotípica podería contribuir ó éxito dalgunhas especies invasoras.[Abstract] Biological invasions are one of the biggest threats to global biodiversity conservation. In recent years there has been many essays focused on discovering which characteristics make a plant become an aggressive invader. Phenotypic plasticity -ability of an individual to adjust their morphological and physiological responses in order to adapt to the environment- could be a key attribute in order to understand invasion processes. In this experiment we use individuals of C.edulis (very aggressive invader) and C.acinaciformis (exotic species, less aggressive invader) in order to compare their plasticity in terms of resources distribution in presence of different soil nutrient concentrations. Our essay shows significative differences in root mass produced by C.edulis and C.acinaciformis depending on the content in soil nutrients, C.edulis showed a higher plasticity for this character. This result seems to support the idea that phenotypic plasticity could contribute to the success of some invasive species.Traballo fin de grao (UDC.CIE). Bioloxía. Curso 2014/201

Fabrication and deposition of copper and copper oxide nanoparticles by laser ablation in open air

The proximity of the “post-antibiotic era”, where infections and minor injuries could be a cause of death, there are urges to seek an alternative for the cure of infectious diseases. Copper nanoparticles and their huge potential as a bactericidal agent could be a solution. In this work, Cu and Cu oxide nanoparticles were synthesized by laser ablation in open air and in argon atmosphere using 532 and 1064 nm radiation generated by nanosecond and picosecond Nd:YVO4 lasers, respectively, to be directly deposited onto Ti substrates. Size, morphology, composition and the crystalline structure of the produced nanoparticles have been studied by the means of field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), the energy dispersive spectroscopy of X-rays (EDS), selected area electron diffraction (SAED) and X-ray diffraction (XRD). The UV-VIS absorbance of the thin layer of nanoparticles was also measured, and the antibacterial capacity of the obtained deposits tested against Staphylococcus aureus. The obtained deposits consisted of porous coatings composed of copper and copper oxide nanoparticles interconnected to form chain-like aggregates. The use of the argon atmosphere contributed to reduce significantly the formation of Cu oxide species. The synthesized and deposited nanoparticles exhibited an inhibitory effect upon S. aureus.Peer ReviewedPostprint (published version

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A simulation study regarding different aircraft boarding strategies

The airline industry is constantly subject to the search of new methods in order to increase efficiency, profitability, and customer satisfaction. Since airlines only generate revenue when their airplanes are on the air, the time they spend at the airports should be the shortest possible. Hence, the airplane turnaround time becomes a process which airlines pay special attention on. The boarding process has a very important role, since it is one of the significant elements of the turnaround time, and a slow boarding process might lead to many kinds of problems to the airline, from financial issues to customer complaints. This paper analyzes the major interferences among the passengers that cause delays in boarding times, and after comparing the different aircraft boarding strategies, it proposes the most efficient strategy.Peer ReviewedPostprint (published version

Recruitment patterns of decapod crustacean megalopae in a shallow inlet (SW Spain) related to life history strategies

Decapod crustacean megalopae were sampled weekly (spring/neap tides) during late-spring/summer of 1998 by using two planktonic nets located close to the surface and the bottom, at a fixed station in the mouth of the Rı́o San Pedro inlet (SW Spain). Sampling was carried out during 25 h cycles to ascertain the flux of megalopae in relation to the main environmental (diel, tidal, tidal amplitude) cycles. The hypothesis that megalopae of some species may be using tidal-stream transport as a mechanism of re-invading the inlet was tested and the relationship between megalopal behaviour and life history strategy was analysed. In general, the flux of megalopae was higher during spring tides, but such differences were only statistically significant for Pisidia longicornis and Liocarcinus sp.2 due to the considerable interdate variation. With the exception of Macropodia sp., megalopae were more abundant close to the bottom. The diel/tidal flux of most abundant species suggested two different patterns of behaviour: megalopae of Liocarcinus spp., Panopeus africanus, Uca tangeri and Brachynotus sexdentatus seemed to be re-invading the inlet (specially at nocturnal floods), while megalopae of Ilia nucleus, Nepinnotheres pinnotheres and Macropodia sp. may have been just looking for a suitable place for settlement. The first group corresponded to the species whose zoeal development occurs in open sea, and the second one to species that complete their life cycle within the studied system, suggesting a relationship between the duration of the larval phase and the life cycle strategy of the species

Influence of inflammation in the process of T lymphocyte differentiation: Proliferative, metabolic, and oxidative changes

T lymphocytes, from their first encounter with their specific antigen as naïve cell until the last stages of their differentiation, in a replicative state of senescence, go through a series of phases. In several of these stages, T lymphocytes are subjected to exponential growth in successive encounters with the same antigen. This entire process occurs throughout the life of a human individual and, earlier, in patients with chronic infections/pathologies through inflammatory mediators, first acutely and later in a chronic form. This process plays a fundamental role in amplifying the activating signals on T lymphocytes and directing their clonal proliferation. The mechanisms that control cell growth are high levels of telomerase activity and maintenance of telomeric length that are far superior to other cell types, as well as metabolic adaptation and redox control. Large numbers of highly differentiated memory cells are accumulated in the immunological niches where they will contribute in a significant way to increase the levels of inflammatory mediators that will perpetuate the new state at the systemic level. These levels of inflammation greatly influence the process of T lymphocyte differentiation from naïve T lymphocyte, even before, until the arrival of exhaustion or cell death. The changes observed during lymphocyte differentiation are correlated with changes in cellular metabolism and these in turn are influenced by the inflammatory state of the environment where the cell is located. Reactive oxygen species (ROS) exert a dual action in the population of T lymphocytes. Exposure to high levels of ROS decreases the capacity of activation and T lymphocyte proliferation; however, intermediate levels of oxidation are necessary for the lymphocyte activation, differentiation, and effector functions. In conclusion, we can affirm that the inflammatory levels in the environment greatly influence the differentiation and activity of T lymphocyte populations. However, little is known about the mechanisms involved in these processes. The elucidation of these mechanisms would be of great help in the advance of improvements in pathologies with a large inflammatory base such as rheumatoid arthritis, intestinal inflammatory diseases, several infectious diseases and even, cancerous processes

Oxy-fired fluidized bed combustors with a flexible power output using circulating solids for thermal energy storage

This paper presents a power plant concept based on an oxy-fired circulating fluidized bed combustor (oxy-CFBC) combined with thermal energy storage on a large scale. The concept exploits to full advantage the large circulation flows of high temperature solids that are characteristic of these systems. Two solid storage silos (one for high temperature and the other for low temperature solids) connected to the oxy-fired CFBC allow variability in power output without the need to modify the fuel firing rate and/or the mass flow of O2 to the combustor. During the periods of high power demand the system can deliver additional thermal power by extracting heat from a series of fluidized bed heat exchangers fed with solids from the high temperature silo. Likewise, during period of low power demand, the thermal power output can be reduced by using the energy released in the combustor to heat up the low temperature solids on their way from the low temperature silo to the oxy-CFBC and storing them in the high temperature silo located below the cyclone. A preliminary economic analysis of two designs indicates that this highly flexible system could make this type of power plant more competitive in the electricity markets where fossil fuels with CCS will be required to respond to a large variability in power output.Y.A. Criado thanks the Government of the Principality of Asturias for a Ph.D. fellowship (Severo Ochoa Program). B. Arias thanks the Spanish MINECO for the award of a Ramon y Cajal contract.Peer reviewe

Using dates as contextual information for personalised cultural heritage experiences

We present semantics-based mechanisms that aim to promote reflection on cultural heritage by means of dates (historical events or annual commemorations), owing to their connections to a collection of items and to the visitors’ interests. We argue that links to specific dates can trigger curiosity, increase retention and guide visitors around the venue following new appealing narratives in subsequent visits. The proposal has been evaluated in a pilot study on the collection of the Archaeological Museum of Tripoli (Greece), for which a team of humanities experts wrote a set of diverse narratives about the exhibits. A year-round calendar was crafted so that certain narratives would be more or less relevant on any given day. Expanding on this calendar, personalised recommendations can be made by sorting out those relevant narratives according to personal events and interests recorded in the profiles of the target users. Evaluation of the associations by experts and potential museum visitors shows that the proposed approach can discover meaningful connections, while many others that are more incidental can still contribute to the intended cognitive phenomena

Variation in Thermal Sensitivity and Thermal Tolerances in an Invasive Species across a Climatic Gradient: Lessons from the Land Snail Cornu aspersum

The ability of organisms to perform at different temperatures could be described by a continuous nonlinear reaction norm (i.e., thermal performance curve, TPC), in which the phenotypic trait value varies as a function of temperature. Almost any shift in the parameters of this performance curve could highlight the direct effect of temperature on organism fitness, providing a powerful framework for testing thermal adaptation hypotheses. Inter-and intraspecific differences in this performance curve are also reflected in thermal tolerances limits (e.g., critical and lethal limits), influencing the biogeographic patterns of species' distribution. Within this context, here we investigated the intraspecific variation in thermal sensitivities and thermal tolerances in three populations of the invasive snail Cornu aspersum across a geographical gradient, characterized by different climatic conditions. Thus, we examined population differentiation in the TPCs, thermal-coma recovery times, expression of heat-shock proteins and standard metabolic rate (i.e., energetic costs of physiological differentiation). We tested two competing hypotheses regarding thermal adaptation (the "hotter is better" and the generalist-specialist trade-offs). Our results show that the differences in thermal sensitivity among populations of C. aspersum follow a latitudinal pattern, which is likely the result of a combination of thermodynamic constraints ("hotter is better") and thermal adaptations to their local environments (generalist-specialist trade-offs). This finding is also consistent with some thermal tolerance indices such as the Heat-Shock Protein Response and the recovery time from chill-coma. However, mixed responses in the evaluated traits suggest that thermal adaptation in this species is not complete, as we were not able to detect any differences in neither energetic costs of physiological differentiation among populations, nor in the heat-coma recovery. © 2013 Gaitán-Espitia et al.Link_to_subscribed_fulltex