1,105 research outputs found

    Immigration and early life stages recruitment of the European flounder (Platichthys flesus) to an estuarine nursery: the influence of environmental factors

    Get PDF
    Connectivity between coastal spawning grounds and estuarine nurseries is a critical step in the life cycle of many fish species. Larval immigration and transport-associated physical–biological processes are determinants of recruitment success to nursery areas. The recruitment of the European flounder, Platichthys flesus, to estuarine nurseries located at the southern edge of the species distribution range, has been usually investigated during its juvenile stages, while estuarine recruitment during the earlier planktonic life stage remains largely unstudied. The present study investigated the patterns of flounder larval recruitment and the influence of environmental factors on the immigration of the early life stages to the Lima estuary (NW Portugal), integrating data on fish larvae and post-settlement individuals (< 50 mm length), collected over 7 years. Late-stage larvae arrived at the estuary between February and July and peak abundances were observed in April. Post-settlement individuals (< 50 mm) occurred later between April and October, whereas newly-settled ones (< 20 mm) were found only in May and June. Variables associated with the spawning, survival and growth of larvae in the ocean (sea surface temperature, chlorophyll a and inland hydrological variables) were the major drivers of flounder occurrence in the estuarine nursery. Although the adjacent coastal area is characterized by a current system with strong seasonality and mesoscale variability, we did not identify any influence of variables related with physical processes (currents and upwelling) on the occurrence of early life stages in the estuary. A wider knowledge on the influence of the coastal circulation variability and its associated effects upon ocean-estuarine connectivity is required to improve our understanding of the population dynamics of marine spawning fish that use estuarine nurseries

    Nuevos aspectos sobre la ecología de los estados iniciales de desarrollo de Sardina pilchardus (Walbaum, 1792) en el norte del Atlántico ibérico

    Get PDF
    In the Atlantic Iberian estuaries, sardines tend to be a minor component of the ichthyoplankton assemblages, with rare occurrence largely restricted to estuarine mouths. However, this was not the case of the Lima estuary (NW Portugal), where sardines were the most abundant and frequently occurring marine taxon of the larval fish assemblages. Abundance of sardines collected during a two-year survey (2002-2004) ranged from 0.5 to 60.8 larvae/100 m3, with the majority still showing yolk and unpigmented eyes. Moreover, 80% of sardines were 8 days old or less and the total length ranged from 2 to 16 mm. Seasonal variations of sardine occurrence in the Lima estuary correlated with temporal variations of salinity and temperature in the water column. The unusually high river-flow observed during the winter of 2002-2003, which preceded the spring-summer abundance peak, seemed to act as a signal for the estuarine recruitment that was encountered. In addition, the estuarine occurrence of sardine larvae was also correlated with the intensity of summer upwelling, which was responsible for coastal depletion of sardine larvae resulting in estuarine low catches during the summer of 2002. The Lima estuary also revealed another peculiarity related to the lack of temporal synchrony between coastal spawning activity and occurrence of larvae within the estuary. The abundance peaks of newly-hatched larvae (autumn 2002 and spring-summer 2003) did not coincide with the winter-spring spawning pattern described earlier for the northern Iberian coast. Modifications of the spawning strategy of the northern Iberian sardine stock are discussed based on these new insights into the early life of S. pilchardus.Las sardinas tienden a ser un componente menor del ictioplancton de los estuarios atlánticos ibéricos. Su aparición es rara y restringida, en gran parte, a las desembocaduras de los ríos. Sin embargo, éste no fue el caso del estuario del río Lima (NW Portugal), donde las sardinas fueron la especie marina más abundante del ictioplanton estuarino. Las sardinas fueron recolectadas durante un período de dos años (2002-2004), y su abundancia varió entre 0.5-60.8 larvas/100 m3. La mayoría de dichas larvas todavía presentaban saco vitelino y ojos no pigmentados. Por otra parte, el 80% de las sardinas tenían 1 semana o menos de vida y su longitud total varió entre 2 y 16 mm. Las variaciones estacionales en la aparición de larvas de sardina en el estuario del río Lima se correlacionaron con fluctuaciones temporales de salinidad y de temperatura de la columna de agua. Los elevados caudales del río observados durante el invierno 2002-2003, que precedieron el pico de abundancia del primavera-verano, parecieron actuar como señal para el reclutamiento al estuario. Además, la aparición en el estuario de larvas de sardina también fue controlada por la intensidad del afloramiento de verano, responsable de la disminución de abundancia de larvas de sardina en la costa, lo que dio lugar a bajas capturas en el estuario durante el verano 2002. Además la inusual aparición de larvas de sardina, dentro del estuario del río Lima reveló otra particularidad relacionada con la carencia de sincronía temporal entre la actividad de freza y la aparición de larvas dentro del estuario. Los picos de abundancia de larvas recién eclosionadas (otoño 2002 y período de primavera-verano de 2003) no coincidieron con la época de puesta invernal previamente descrita para la costa norte de la península ibérica. Estos nuevos datos sobre la ecología de los estados iniciales de desarrollo de la sardina se discuten a la luz de las modificaciones de la estrategia reproductiva del stock de sardinas del norte del Atlántico ibérico

    MATERIAL CHARACTERISATION OF A FLORENTINE PAINTER IN PORTUGAL IN THE LATE 19TH CENTURY: PAINTINGS BY GIORGIO MARINI

    Get PDF
    This paper presents the analytical characterisation of a series of paintings authored by Giorgio Marini (1836-1905) from the Museum of Évora. Marini was an Italian painter who lived in Portugal in the 19th century. He was a very prolific painter and his works, most of them portraits commissioned by urban and rural bourgeois and noble elites, are dispersed all over the country. The general good conservation state of most paintings prevented the collection of micro-samples for detailed study. Hence, material identification of the painting materials was performed primarily by XRF, given its non-destructive and non-invasive nature, and it was complemented when possible by auxiliary techniques optical microscopy, Raman spectroscopy, and SEM-EDX. Pigments and fillers such as yellow and red ochre, lead white, zinc white, barium white, chrome yellow and green chrome are among the identified pigments. This is the first time the palette used by Giorgio Marini was identified, helping to characterised the pigments used by foreign painters during the 19th century in Portuga

    D-branes and orientifolds of SO(3)

    Get PDF
    We study branes and orientifolds on the group manifold of SO(3). We consider particularly the case of the equatorial branes, which are projective planes. We show that a Dirac-Born-Infeld action can be defined on them, although they are not orientable. We find that there are two orientifold projections with the same spacetime action, which differ by their action on equatorial branes.Comment: 11 pages, no figure, uses JHEP3.cls. V2 : minor correction

    The one-third law of evolutionary dynamics

    Get PDF
    Evolutionary game dynamics in finite populations provide a new framework for studying selection of traits with frequency-dependent fitness. Recently, a “one-third law” of evolutionary dynamics has been described, which states that strategy A fixates in a B-population with selective advantage if the fitness of A is greater than that of B when A has frequency 1/3. This relationship holds for all evolutionary processes examined so far, from the Moran process to games on graphs. However, the origin of the “number” 1/3 is not understood. In this paper we provide an intuitive explanation by studying the underlying stochastic processes. We find that in one invasion attempt, an individual interacts on average with B-players twice as often as with A-players, which yields the one-third law. We also show that the one-third law implies that the average Malthusian fitness of A is positive

    Could Estradiol be used as a biomarker of infection in Schistosoma haematobium infected patients?

    Get PDF
    Urogenital schistosomiasis is a chronic infection caused by the human blood fluke Schistosoma haematobium. Schistosomiasis haematobia is a known risk factor for cancer leading to squamous cell carcinoma of the urinary bladder (SCC). This is a neglected tropical disease endemic in many countries of Africa and the Middle East. Schistosome eggs produce catechol-estrogens. These estrogenic molecules are metabolized to active quinones that cause alterations in DNA (leading in other contexts to breast or thyroid cancer). Our group has shown that schistosome egg associated catechol estrogens induce tumor-like phenotypes in urothelial cells, originated from parasite estrogen-host cell chromosomal DNA adducts and mutations. Also we have demonstrated that these molecules are detected as Estradiol in sera of infected patients.N/

    De Novo Hypertension and Decline of Renal Function in a Young Woman with Systemic Lupus Erythematosus and Antiphospholipid Syndrome

    Get PDF
    Antiphospholipid syndrome nephropathy and lupus nephritis have similar clinical and laboratory manifestations and achieving the accuracy of diagnosis required for correct treatment frequently necessitates a kidney biopsy. We report the case of a 29-year-old woman referred to the nephrology service for de novo hypertension, decline of renal function and proteinuria. She had had systemic lupus erythematosus and antiphospholipid syndrome since the age of 21 and was taking oral anticoagulation. Two weeks later, after treatment of hypertension and achievement of adequate coagulation parameters, a percutaneous renal biopsy was performed. The biopsy revealed chronic lesions of focal cortical atrophy, arterial fibrous intimal hyperplasia and arterial thromboses, which are typical features of antiphospholipid syndrome nephropathy. We describe the clinical manifestations and histopathology of antiphospholipid syndrome nephropathy and review the literature on renal biopsy in patients receiving anticoagulation

    Paper-Based Biosensors for Analysis of Water

    Get PDF
    The presence of contaminants in water generates a great concern worldwide. As contaminants, we can refer different classes of chemicals, such as pharmaceuticals, personal care products, heavy metals, and also microorganisms, such as waterborne pathogens. Some of the chemical compounds have the potential to bioaccumulate in the aquatic biota. Hence, the development of simple and portable methods for the detection of contaminants in the aquatic environment can improve their monitoring and, consequently, the study of their environmental impact. In this context, the development of paper-based analytical tools and also of biosensor devices has been exploited for quantitative and semiquantitative analysis of several contaminants in different water matrices. The association of these two analytical strategies can provide the implementation of low-cost, portable, and easily handled methods for detecting chemical and biological contaminations in water. In this chapter, we provide a review of the developed paper-based analytical biosensors, highlighting the features of the paper-based (paper substrate and fabrication procedures) and biosensor devices (transducers and biorecognition elements). Moreover, the application of the referred paper-based biosensors for the detection of different water contaminants (pathogens, pharmaceuticals, and heavy metals) in environmental and wastewater samples is discussed
    corecore