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The effect of the presence and angular position of a refuge on the direction and kinematics of mechanically-induced escape responses was observed in staghorn sculpins Leptocottus armatus using high-speed video. The results showed that the angular position of the refuge did not affect locomotor performance (speed and acceleration), although it did affect the escape trajectories. Therefore, the angular position of a refuge can modulate the direction taken by the L. armatus during the early stages of their escape response and this response can be affected by both repulsive (i.e. threats) and attractive (i.e. refuges) points of reference.
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Ambiente , Reacción de Fuga , Perciformes/fisiología , Aceleración , Animales , Fenómenos BiomecánicosRESUMEN
Although muon spin relaxation is commonly used to probe local magnetic order, spin freezing, and spin dynamics, we identify an experimental situation in which the measured response is dominated by an effect resulting from the muon-induced local distortion rather than the intrinsic behavior of the host compound. We demonstrate this effect in some quantum spin ice candidate materials Pr(2)B(2)O(7) (B=Sn, Zr, Hf), where we detect a static distribution of magnetic moments that appears to grow on cooling. Using density functional theory we show how this effect can be explained via a hyperfine enhancement arising from a splitting of the non-Kramers doublet ground states on Pr ions close to the muon, which itself causes a highly anisotropic distortion field. We provide a quantitative relationship between this effect and the measured temperature dependence of the muon relaxation and discuss the relevance of these observations to muon experiments in other magnetic materials.
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We investigated an outbreak of fever most likely due to a contaminated whirlpool among nine adults and six children visiting a holiday home. The outbreak was characterized by a high attack rate, short incubation periods, influenza-like symptoms and rapid recoveries typical of Pontiac fever. The children, however, experienced less characteristic symptoms and no sequelae compared to the adults. Evidence and presumptive evidence of Legionella (L) infection was found in eleven cases; in one case by isolation of L. pneumophila serogroup 1, in two cases by positive test for Legionella by PCR and in eleven cases with seroconversion. In contrast, two adult non-users of the whirlpool had no symptoms and no serological evidence of infection. This investigation demonstrates differences between adults and children in the clinical picture of Pontiac fever, furthermore it shows that culture and PCR of tracheal aspirate for legionellae can be used in a hospital setting for rapid diagnosis although their sensitivities are low.
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Brotes de Enfermedades , Fiebre/microbiología , Legionelosis/diagnóstico , Piscinas , Microbiología del Agua , Adulto , Factores de Edad , Niño , Preescolar , Dinamarca , Femenino , Fiebre/diagnóstico , Fiebre/etiología , Humanos , Legionella pneumophila/genética , Legionelosis/etiología , MasculinoRESUMEN
We have observed an electronic energy level crossing in a molecular nanomagnet (MNM) using muon spin relaxation. This effect, not observed previously despite several muon studies of MNM systems, provides further evidence that the spin relaxation of the implanted muon is sensitive to the dynamics of the electronic spin. Our measurements on a broken ring MNM [H(2)N(t)Bu(is)Pr][Cr(8)CdF(9)(O(2)CC(CH(3))(3))(18)], which contains eight Cr ions, show clear evidence for the S = 0 --> S = 1 transition that takes place at B(c) = 2.3 T. The crossing is observed as a resonance-like dip in the average positron asymmetry and also in the muon spin relaxation rate, which shows a sharp increase in magnitude at the transition and a peak centred within the S = 1 regime.
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Magnetismo/instrumentación , Mesones , Modelos Químicos , Nanotecnología/instrumentación , Simulación por Computador , Diseño de Equipo , Análisis de Falla de Equipo , Ensayo de MaterialesRESUMEN
In this study the relationship between temperament and development in preschool children was determined. Thirty-one children, age 3 and 4 years old, were selected from day-care centers. The child's temperament was measured with the Behavioral Style Questionnaire. Cognitive-verbal and motor development were assessed using the Peabody Picture Vocabulary Test, the Goodenough Draw-a-Person Test, and the developmental subtests of the Comprehensive Identification Process. Significant correlations (p less than .05) using the Pearson product moment were found between development and six categories of reactivity for temperament: activity, rhythmicity, approach, adaptability, mood, and persistence. All significant correlation coefficients showed an inverse relationship between temperament and developmental scores. This suggests that children who are mildly active, rhythmic, adaptable, persistent, approachable, and have a positive mood attain a more advanced developmental level during their preschool years.