86,831 research outputs found
Fire salamander (<i>Salamandra salamandra</i>) covered with <i>Bsal</i> ulcerations, which are visible as black spots (photo credit = F. Pasmans).
No full text<p>Fire salamander (<i>Salamandra salamandra</i>) covered with <i>Bsal</i> ulcerations, which are visible as black spots (photo credit = F. Pasmans).</p
Designing screening protocols for amphibian disease that account for imperfect and variable capture rates of individuals
No full textThe amphibian chytrid fungus, Batrachochytrium dendrobatidis, is one of the main factors in global amphibian decline. Accurate knowledge of its presence and prevalence in an area is needed to trigger conservation actions. However, imperfect capture rates determine the number of individuals caught and tested during field surveys, and contribute to the uncertainty surrounding estimates of prevalence. Screening programs should be planned with the objective of minimizing such uncertainty. We show how this can be achieved by using predictive models that incorporate information about population size and capture rates. Using as a case study an existing screening program for three populations of the yellow-bellied toad (Bombina variegata pachypus) in northern Italy, we sought to quantify the effect of seasonal variation in individual capture rates on the uncertainty surrounding estimates of chytrid prevalence. We obtained estimates of population size and capture rates from mark-recapture data, and found wide seasonal variation in the individual recapture rates. We then incorporated this information in a binomial model to predict the estimates of prevalence that would be obtained by sampling at different times in the season, assuming no infected individuals were found. Sampling during the period of maximum capture probability was predicted to decrease upper 95% credible intervals by a maximum of 36%, compared with least suitable periods, with greater gains when using uninformative priors. We evaluated model predictions by comparing them with the results of screening surveys in 2012. The observed results closely matched the predicted figures for all populations, suggesting that this method can be reliably used to maximize the sampling size of surveillance programs, thus improving their efficiency
No detection of chytrid in first systematic screening of Bombina variegata pachypus (Anura: Bombinatoridae) in Liguria, northern Italy
No full textThe Apennine Yellow-bellied toad Bombina variegata pachypus, a small anuran endemic to peninsular Italy, has been declining throughout its range over the last 30 years. Although mortality by chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, was first reported for the species in 2004, its role in the decline has not yet been assessed. Between 2011 and 2012 we sampled eight populations of B. v. pachypus in Liguria, northern Italy, swabbing 86 and 143 individuals respectively, corresponding to between 24 and 80% of the estimated individuals within each population. We did not detect chytrid in any the samples collected. For the three largest populations in the region, we can rule out infections of prevalence greater than 10% with at least 98% confidence. Research at a larger scale is urgently needed to clarify the role of B. dendrobatidis in the decline of this and other amphibians in Italy
<i>Bsal</i> infection in the skin of a fire salamander (<i>Salamandra salamandra</i>), characterized by extensive epidermal necrosis, presence of high numbers of intra-epithelial colonial chytrid thalli, and loss of epithelial integrity (H&E staining, scale bar = 50 μm; photo credit = A. Martel and F. Pasmans).
No full text<p><i>Bsal</i> infection in the skin of a fire salamander (<i>Salamandra salamandra</i>), characterized by extensive epidermal necrosis, presence of high numbers of intra-epithelial colonial chytrid thalli, and loss of epithelial integrity (H&E staining, scale bar = 50 μm; photo credit = A. Martel and F. Pasmans).</p
Local electrochemical behaviour of 7xxx aluminium alloys
No full textAluminium alloys of the 7xxx series (Al-Zn-Mg-Cu) are susceptible to localized types of corrosion like pitting, intergranular corrosion and exfoliation corrosion. This represents a limitation for the application of these alloys in the aerospace components because localized corrosion might have a negative effect on safety and costs. This PhD thesis investigates the relation between electrochemical behaviour and microstructure of a number of 7xxx aluminium alloys: AA7075, AA7349 and an experimental alloy (EA1) with composition in the range of AA7449. To this aim, the experimental approach of this PhD consisted in the characterization of the microstructure of the alloys combined with the study of their electrochemical behaviour. The investigation of the microstructure focused on intermetallics and strengthening particles because these second phase particles strongly affect the corrosion behaviour of 7xxx aluminium alloys. The study of the electrochemical behaviour was approached on two different levels: macro- and micro-electrochemical characterization of the alloys. The macro-electrochemical characterization employed open circuit potential and potentiodynamic polarization measurements to study the overall corrosion behaviour of the alloys, while the micro-electrochemical characterization applied local electrochemical techniques (scanning Kelvin probe force microscope and micro-capillary cell) to study the local behaviour of the intermetallics. There are three main types of intermetallics in the 7xxx alloys investigated: - Al7Cu2Fe - (Al,Cu)6(Fe,Cu) - Mg2Si In AA7349 and EA1 the intermetallics contain small amounts of Mn and Si. The strengthening particles are Mg2Zn phase for all alloys. The intermetallics are not affected by heat treatments (solution heat treatment, aging and overaging), while the strengthening particles undergo strong changes. The strengthening particles are dissolved by solution heat treatment resulting in supersaturation of solute elements (Zn and Mg) in the matrix and in segregation of these elements at the grain boundaries. They precipitate in the matrix and at the grain boundaries during aging and overaging progressively reducing the supersaturation of the matrix and the segregation at the grain boundaries. The intermetallics are the initiation sites for localized corrosion, which takes place as local dissolution of the matrix at the location of the intermetallics and results in pitting of the alloy surface. At a later stage, the localized attack propagates as intergranular corrosion and might turn into exfoliation corrosion for microstructures particularly susceptible to the intergranular attack. The types of intermetallics in the microstructure of the alloys exhibit different micro- electrochemical behaviour. The Al7Cu2Fe and (Al,Cu)6(Fe,Cu) intermetallics have cathodic behaviour relative to the matrix (positive Volta potential difference relative to the matrix), while the Mg2Si intermetallics have anodic behaviour (negative Volta potential difference relative to the matrix). Moreover, the Al7Cu2Fe intermetallics have stronger cathodic behaviour than the (Al,Cu)6(Fe,Cu) intermetallics. The microstructural changes taking place during solution heat treatment strongly affect the electrochemical behaviour of the alloys. Solution heat treatment strongly increases the Volta potential difference between the intermetallics and the matrix (for all types of intermetallics) increasing the susceptibility to pitting. Moreover, it increases the susceptibility to intergranular and exfoliation corrosion because of the segregation of Zn and Mg at the grain boundaries. Aging and overaging decrease the Volta potential difference between the intermetallics and the matrix improving the resistance to pitting. Aging improves the susceptibility to intergranular corrosion as compared to solution heat treatment. However, the alloys aged to the peak-strength tempers are still prone to severe intergranular corrosion and exfoliation corrosion because they undergo precipitation of small strengthening particles at the grain boundaries with very small interparticle spacing. Overaging strongly improves the resistance to intergranular corrosion and eliminates the susceptibility to exfoliation corrosion because it increases the size and the interparticle spacing of the particles at the grain boundaries. The characterization using the local electrochemical techniques (scanning Kelvin probe force microscope and micro-capillary cell) showed that the micro- electrochemical behaviour of the intermetallics is different for each intermetallic. This means that some areas of the alloy surface might be very susceptible to localized attack and might be preferential sites for the initiation of localized corrosion. The local electrochemical techniques used in this PhD enable the relation of the electrochemical behaviour to the microstructure of the alloys. In particular, it was possible to establish this relationship for the intermetallics due to the lateral resolution of these techniques (in the micrometer range). This thesis has proved that the complementary use of local electrochemical techniques is very useful for the characterization of metals that are susceptible to localized types of corrosion.Applied Science
An avirulent Brachyspira hyodysenteriae strain elicits intestinal IgA and slows down spread of swine dysentery
No full textSwine dysentery caused by Brachyspira hyodysenteriae, results in substantial economic losses in swine producing countries worldwide. Although a number of different vaccine approaches have been explored with regard to this disease, they show limitations and none of them have reached the market. We here determine the vaccine potential of a weakly haemolytic B. hyodysenteriae strain. The virulence of this strain was assessed in experimental infection trials and its protection against swine dysentery was quantified in a vaccination-challenge experiment using a seeder infection model. Systemic IgG production and local IgA production were monitored in serum and faeces respectively. Across all trials, pigs that were colonized by virulent, strongly haemolytic B. hyodysenteriae strains consistently developed swine dysentery, in contrast to none of the pigs colonized by the weakly haemolytic B. hyodysenteriae vaccine strain. In the seeder vaccination trial nearly all immunised animals developed swine dysentery on subsequent challenge with a virulent strain, but the speed of spread of swine dysentery and faecal score were significantly reduced in animals immunised with the weakly haemolytic strain compared to sham-immunised animals. The IgA response of immunised animals upon challenge with a virulent B. hyodysenteriae strain significantly correlated to a later onset of disease. The correlation between local IgA production and protection induced by a weakly haemolytic B. hyodysenteriae strain provides leads for future vaccine development against swine dysentery
Distribution and morphological characterization of the endemic Italian salamanders Salamandrina perspicillata (Savi, 1821) and S. terdigitata (Bonnaterre, 1789) (Caudata: Salamandridae)
No full textThe Italian endemic genus Salamandrina was recently determined to be polytypic since two species, Salamandrina perspicillata and S. terdigitata, were recognized using both mitochondrial and nuclear genetic markers. However, data on their range is very scanty and no morphological traits are available to distinguish between these two taxa. A thorough field survey was carried out to detect and to sample new sites in areas in which Salamandrina remained unrecorded and to sample populations expected to occur in the documented range. Specimens were analyzed for variation of three mitochondrial DNA partial sequences of 12S and 16S ribosomal RNAs and cytochrome b genes. Attribution of individuals to either of the two species was therefore made on the basis of their haplotypes. Here we provide relevant information on the distribution of the two species, which were also found in areas where Salamandrina had previously been unrecorded, i.e. in the eastern Basilicata, in the region of Apulia and within the wide area which separated the two species. In the latter zone, a small area of sympatry between the two species was found. Furthermore, we analyzed the dorsal coloration pattern and size-related characters of the two species using Classification and Regression Tree analysis (CART), the results of which provided the first account of the morphological differences between Salamandrina perspicillata and S. terdigitata. The southern species, S. terdigitata, is smaller in size than S. perspicillata and differs in its coloration, mainly due to the red color on the dorsal surface of its tail
Distribuzione geografica delle due specie di Salamandrina in Italia (S. perspicillata e S. terdigitata)
No full textVariations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
[Newspaper Clipping: Author Claims Evidence of Second JFK Assassin #1]
No full textNewspaper article titled "Author Claims Evidence of Second JFK Assassin." The article states that author Richard J. Whalen concluded "that there is circumstantial evidence to support the theory of a second assassin in the shooting of President John F. Kennedy.
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