1,721,444 research outputs found
Vortex pinning by natural defects in thin films of YBa2Cu3O7−δ
Full text linkAlthough vortex pinning in laser-ablated YBa2Cu3O7−δ films on (100) SrTiO3 is dominated by threading dislocations, many other natural pinning sites are present. To identify the contribution from twin planes, surface corrugations and point defects, we manipulate the relative densities of all defects by post-annealing films with various as-grown dislocation densities, ndisl. While a universal magnetic field B dependence of the transport current density js(B, T) is observed (independently of ndisl, temperature T and the annealing treatment), the defect structure changes considerably. Correlating the microstructure to js(B, T), it becomes clear that surface roughness, twins and point defects are not important at low magnetic fields compared to linear defect pinning. Transmission electron microscopy indicates that threading dislocations are not part of grain boundaries nor are they related to the twin domain structure. We conclude that js(B, T) is essentially determined by pinning along threading dislocations, naturally induced during the growth process. Even in high magnetic fields, where the vortex density outnumbers ndisl, it appears that linear defects stabilize the vortex lattice by means of the vortex–vortex interaction.
Monte Carlo simulation to evaluate the contamination in an energy modulated carbon ion beam for hadron therapy delivered by cyclotron
No full textProtons and carbon ion beams for hadron therapy can be delivered by cyclotrons with a fixed energy. In order to treat patients, an energy degrader along the beam line will be used to match the particle range with the target depth. Fragmentation reactions of carbon ions inside the degrader material could introduce a small amount of unwanted contaminants to the beam, giving additional dose to the patient out of the target volume. A simulation study using the FLUKA Monte Carlo code has been carried out by considering three different materials as the degrader. Two situations have been studied: a realistic one, lowering the carbon beam energy from 300 MeV/n to 220 MeV/n, corresponding to a range of 10 cm in water, and the worst possible case, lowering the carbon energy to 50 MeV/n, corresponding to the millimeter range. The main component of the contaminant is represented by alpha particles and protons, with a typical momentum after the degrader greater than that of the primary beam, and can be eliminated by the action of a momentum analyzing system and slits, and by a second thin absorber. The residual component of fragments reaching the patient is negligible with respect to the fragment quantity generated by the primary beam inside the patient before arriving at the end of the target volume
Distribution of trace elements in the tissues of smooth hound Mustelus mustelus (Linnaeus, 1758) from the southern-eastern waters of Mediterranean Sea (Italy)
No full textTrace element concentrations (Hg, Cd, Pb, Cr, Ni, Cu, Zn) were determined in the muscle, gonads, skin, and brain of smooth hound Mustelus mustelus in order to define the metal distribution patterns. The data indicated that metal accumulation depended on the tissues probably as a consequence of metabolic needs, physiochemical properties, and detoxification processes specific for each element. Metal concentrations were higher in gonads (Hg 0.10–0.70 μg g − 1; Cd 0.02–0.10 μg g − 1; Pb 0.08–0.39 μg g − 1; Cr 0.06–0.36 μg g − 1; Ni 1.37–3.00 μg g − 1; Zn 9.15–16.30 μg g − 1; Cu 1.95–21.62 μg g − 1) and skin (Hg 0.16–0.66 μg g − 1; Cd 0.01–0.04 μg g − 1; Pb 0.10–0.62 μg g − 1; Cr 0.15–0.68 μg g − 1; Ni 1.60–7.20 μg g − 1; Zn 9.00–16.00 μg g − 1; Cu 0.78–6.80 μg g − 1) than brain (Hg 0.04–0.34 μg g − 1; Cd 0.01–0.05 μg g − 1; Pb 0.03–0.59 μg g − 1; Cr 0.08–0.48 μg g − 1; Ni 5.59–9.69 μg g − 1; Zn 5.90–7.35 μg g − 1; Cu 0.90–4.02 μg g − 1), while muscle always exhibited the lowest levels (Hg 1.03–2.58 μg g − 1; Cd 0.01–0.06 μg g − 1; Pb 0.02–0.16 μg g − 1; Cr 0.05–0.28 μg g − 1; Ni 1.13–2.48 μg g − 1; Zn 2.64–5.06 μg g − 1; Cu 0.33–2.23 μg g − 1). Ni and Hg took exception having the highest concentrations in brain and muscle, respectively. An assessment of the risk for human due to the consumption of these marine organisms was also undertaken. Regarding Cd and Pb intakes, consumption did not guide to any concerns, while it should be extremely moderate when considering Hg intake. The comparative analyses revealed that Mediterranean sharks were exposed to higher Hg levels than biota inhabiting open ocean
Excavating sponges from the Adriatic Sea: description of Cliona adriatica sp. nov. (Demospongiae: Clionaidae) and estimation of its boring activity
No full textL’ECOGRAFIA QUALE AUSILIO DIAGNOSTICO IN CORSO DI PATOLOGIE DELLA MAMMELLA DELLA BOVINA DA LATTE
No full textTwenty-five dairy cows were subjected to clinical investigation followed by clinical examination and ultrasonography of mammary glands. Secretions and tissue samples taken from each animal were subjected to histological and microbiological examinations. After clinical evaluation, animals were slaughtered and mammary parenchyma macroscopically evaluated. According to our results, ultrasonography in the diagnosis of mastitis does not involve a significant advance for practical applications compared to laboratory investigations so far applied. However, it allows a corrected characterization of the lesion by directing the clinician in selecting therapeutic and prognostic evaluation
Excavating sponges from the Adriatic Sea: description and estimation of the boring activity of the new clionaid species Cliona adriatica (Porifera, Demospongiae)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“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
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