Aorto-septal angle, isolated basal septal hypertrophy, and systolic murmur in 122 cats.

INTRODUCTION/OBJECTIVES: Systolic murmurs in the absence of cardiac structural abnormalities are common in cats. Narrow aorto-septal angle (AoSA) and septal remodeling can be a cause of a systolic murmur in elderly human beings. The aim of this study was to measure the AoSA in cats and to investigate the association between the AoSA and the presence of a murmur and isolated basal septal hypertrophy (IBSH). ANIMALS: The study population comprised 122 cats. MATERIALS AND METHODS: A physical exam, blood pressure measurement, chest radiographs, and echocardiography were performed. RESULTS: A systolic murmur was audible in 39/122 cats. A difference between cats with and without a murmur was found for age (P=0.0001), interventricular basal septal thickness (BIVSd) (P=0.004), AoSA (P=0.003), aortic (P<0.0001), and pulmonic (P=0.021) flow velocity, the presence of IBSH (P<0.0001), and systolic anterior motion of the mitral valve (P=0.0002). More than 50% of cats with a murmur had an AoSA ≤122°. Less than 25% of the cats with an AoSA ≥137° had a murmur. The AoSA narrowed 0.55°/year of age (P<0.001), whereas the BIVSd increased 0.11 mm/year of age (P<0.0001); the BIVSd increased as the AoSA narrowed. In all cats with AoSA < 120°, IBSH was present. CONCLUSIONS: This study demonstrates that the probability of having a systolic murmur in cats is increased by the presence of a narrow AoSA. Aging was associated with a narrower AoSA and a thicker basal septum; these findings might represent an age-related heart remodeling.

Breaking the ring: 53Cr-NMR on the Cr8Cd molecular nanomagnet.

An accurate experimental characterization of finite antiferromagnetic (AF) spin chains is crucial for controlling and manipulating their magnetic properties and quantum states for potential applications in spintronics or quantum computation. In particular, finite AF chains are expected to show a different magnetic behaviour depending on their length and topology. Molecular AF rings are able to combine the quantum-magnetic behaviour of AF chains with a very remarkable tunability of their topological and geometrical properties. In this work we measure the 53Cr-NMR spectra of the Cr8Cd ring to study the local spin densities on the Cr sites. Cr8Cd can in fact be considered a model system of a finite AF open chain with an even number of spins. The NMR resonant frequencies are in good agreement with the theoretical local spin densities, by assuming a core polarization field A C = -12.7 T µ B -1. Moreover, these NMR results confirm the theoretically predicted non-collinear spin arrangement along the Cr8Cd ring, which is typical of an even-open AF spin chain.

Singling out the effect of quenched disorder in the phase diagram of cuprates.

We investigate the specific influence of structural disorder on the suppression of antiferromagnetic order and on the emergence of cuprate superconductivity. We single out pure disorder, by focusing on a series of [Formula: see text] samples at fixed oxygen content y  = 0.35, in the range [Formula: see text]. The gradual Y/Eu isovalent substitution smoothly drives the system through the Mott-insulator to superconductor transition from a full antiferromagnet with Néel transition [Formula: see text] K at z = 0 to a bulk superconductor with superconducting critical temperature [Formula: see text] K at z = 1, [Formula: see text]. The electronic properties are finely tuned by gradual lattice deformations induced by the different cationic radii of the two lanthanides, inducing a continuous change of the basal Cu(1)-O chain length, as well as a controlled amount of disorder in the active Cu(2)O2 bilayers. We check that internal charge transfer from the basal to the active plane is entirely responsible for the doping of the latter and we show that superconductivity emerges with orthorhombicity. By comparing transition temperatures with those of the isoelectronic clean system we determine the influence of pure structural disorder connected with the Y/Eu alloy.

Fast recovery of the pristine magnetic and structural phases in superconducting LaFeAsO0.89F0.11 by Mn/Fe substitution.

We report an experimental study on the effect of Mn impurities in the optimally doped [Formula: see text] compound. The results show that a very tiny amount of Mn, of the order of 0.1%, is enough to destroy superconductivity and to recover at low temperatures both the magnetic ground state and the orthorhombic structure of the pristine LaFeAsO parent compound. The results are discussed within a model where electron correlations enhance the Ruderman-Kittel-Kasuya-Yosida interaction among impurities.

Band filling effect on polaron localization in La1-x(Ca(y)Sr1-y)xMnO3 manganites.

We report on a ìSR and 55 Mn NMR investigation of the magnetic order parameter as a function of temperature in the optimally doped La(5/8)(CaySr(1.y))(3/8)MnO3 and in the underdoped La1.xSrxMnO3 and La1.xCaxMnO3 metallic manganite families. The study is aimed at unravelling the effect of lattice distortions, implicitly controlled by the Ca-Sr isoelectronic substitution, from that of hole doping x on the Curie temperature TC and the order of the magnetic transition. At optimal doping, the transitions are second order at all y values, including the y = 1 (La(5/8)Ca(3/8)MnO3) end member. By contrast, they are first order in the underdoped samples, which show a finite (truncated) order parameter at the Curie point, including La(0.75)Sr(0.25)MnO3 whose TC is much higher than that of La(5/8)Ca(3/8)MnO3. The order parameter curves, on the other hand, exhibit a very minor dependence on x, if truncation is excepted. This suggests that the effective exchange interaction between Mn ions is essentially governed by local distortions, in agreement with the original double-exchange model, while truncation is primarily, if not entirely, an effect of under- or over-doping. A phase diagram, separating in the x.y plane polaron-driven first order transitions from regular second order transitions governed by critical fluctuations, is proposed for the La(1.x)(CaySr(1.y))xMnO3 system.

Music-listening habits with MP3 player in a group of adolescents: a descriptive survey.

BACKGROUND: Listening to music through portable MP3 players has become a very popular mode among young people and adolescents. The aim of this study is to investigate the behaviors of adolescents engaged in listening to music with MP3 player and the attendance at clubs (pubs, discotheques) where music is played at high volume. METHODS: Among the 1470 students attending a secondary school in Scandicci (FI) during the school year 2009/2010, 1278 (86.9%) were at school the day of the examination and 1276 completely filled in the questionnaire. Descriptive analysis and univariate and multivariate logistic regression were performed to calculate the degree of association (OR) among the sociodemographic characteristics, listening habits and some factors identified as risky or protective as regards the possibility of developing health disorders. RESULTS: MP3 player users are 88.2% of the sample. Among these, a high proportion engaged behaviours that increase the risk of presenting disorders, including the exposure to high-volume (27.4%). Furthermore, 44.6% use the MP3 while driving. From the regression analysis it emerges that MP3 users showed a sort of addiction: by increasing the time and the occasions of exposure to music, they increased the volume, used maximum or medium-high volume, did not take breaks and did not decrease the volume. CONCLUSIONS: The study points out the spread of risky behavior in music listening, so it is necessary to better inform especially the youngsters and achieve specific preventive interventions.

Correlated trends of coexisting magnetism and superconductivity in optimally electron-doped oxypnictides.

We report on the recovery of the short-range static magnetic order and on the concomitant degradation of the superconducting state in optimally F-doped SmFe(1-x)Ru(x)AsO(0.85)F(0.15) for 0.1≤x≲0.5. The two reduced order parameters coexist within nanometer-size domains in the FeAs layers and eventually disappear around a common critical threshold x(c)~0.6. Superconductivity and magnetism are shown to be closely related to two distinct well-defined local electronic environments of the FeAs layers. The two transition temperatures, controlled by the isoelectronic and diamagnetic Ru substitution, scale with the volume fraction of the corresponding environments. This fact indicates that superconductivity is assisted by magnetic fluctuations, which are frozen whenever a short-range static order appears, and totally vanish above the magnetic dilution threshold x(c).

Nanoscopic coexistence of magnetism and superconductivity in YBa2Cu3O6+x detected by muon spin rotation.

We performed zero and transverse field muon spin rotation experiments on a large number of YBa2Cu3O6+x samples. We detect the coexistence of antiferromagnetic (AF) short range magnetism with superconductivity below T(f) < or = 10 K in compositions 0.37 < or = x < or = 0.39. Most muons experience local AF fields, even when a SQUID detects a full superconducting volume fraction, which points to a local minimal interference organization of short AF stripes embedded in the superconductor. A detailed phase diagram is produced and the consequences of the minimal interference are discussed.

Effect of two gaps on the flux-lattice internal field distribution: evidence of two length scales in Mg(1-x)AlxB2 from muSR.

We have measured the transverse field muon spin precession in the flux-lattice (FL) state of the two-gap superconductor MgB2 and of the electron doped compounds Mg(1-x)AlxB2 in magnetic fields up to 2.8 T. We show the effect of the two gaps on the internal field distribution in the FL, from which we determine two coherence length parameters and the doping dependence of the London penetration depth. This is an independent determination of the complex vortex structure already suggested by the STM observation of large vortices in a MgB2 single crystal. Our data agree quantitatively with STM and we thus validate a new phenomenological model for the internal fields.

Ultraslow polaron dynamics in low-doped manganites from (139)La NMR-NQR and muon spin rotation.

We report a (139)La NMR investigation of low-doped insulating manganite samples (LaMnO(3+delta) and La(1-y)Ca(y)MnO(3+delta)) as a function of temperature. A volume fraction with fast nuclear relaxations was revealed by the inhomogeneous loss of the NMR signal over a broad temperature interval. Comparison with muon spin rotation data demonstrates that the wipeout of the (139)La signal is mainly due to slowly fluctuating electric field gradients. This provides strong evidence for the slow diffusion of lattice excitations, identified with Jahn-Teller small polarons.