19F nuclear spin relaxation and spin diffusion effects in the single ion magnet LiYF4:Ho3+

Temperature and magnetic field dependences of the 19F nuclear spin-lattice relaxation in a single crystal of LiYF4 doped with holmium are described by an approach based on a detailed consideration of the magnetic dipole-dipole interactions between nuclei and impurity paramagnetic ions and nuclear spin diffusion processes. The observed non-exponential long time recovery of the nuclear magnetization after saturation at intermediate temperatures is in agreement with predictions of the spin-diffusion theory in a case of the diffusion limited relaxation. At avoided level crossings in the spectrum of electron-nuclear states of the Ho3+ ion, rates of nuclear spin-lattice relaxation increase due to quasi-resonant energy exchange between nuclei and paramagnetic ions, in contrast to the predominant role played by electronic cross-relaxation processes in the low-frequency ac-susceptibility.Comment: 27 pages total, 5 figures, accepted for publication, Eur. Phys. J.

Near-infrared spectroscopy study of tourniquet-induced forearm ischaemia in patients with coronary artery disease

Near-Infrared Spectroscopy (NIR) can be employed to monitor local changes in haemodynamics and oxygenation of human tissues. A preliminary study has been performed in order to evaluate the NIRS transmittance response to induced forearm ischaemia in patients with coronary artery disease (CAD). The population consists in 40 patients with cardiovascular risk factors and angiographically documented CAD, compared to a group of 13 normal subjects. By inflating and subsequently deflating a cuff placed around the patient arm, an ischaemia has been induced and released, and the patients have been observed until recovery of the basal conditions. A custom LAIRS spectrometer (IRIS) has been used to collect the backscattered light intensities from the patient forearm throughout the ischaemic and the recovery phase. The time dependence of the near-infrared transmittance on the control group is consistent with the available literature. On the contrary, the magnitude and dynamics of the NIRS signal on the CAD patients show deviations from the documented normal behavior, which can be tentatively attributed to abnormal vessel stiffness. These preliminary results, while validating the performance of the IRIS spectrometer, are strongly conducive towards the applicability of the NIRS technique to ischaemia analysis and to endothelial dysfunction characterization in CAD patients with cardiovascular risk factors.Publisher PD

Nota preliminar sobre la presencia de estructuras fluidales en las ofitas del area de Estopiñán (Provincia de Huesca)

Se describen las estructuras fluidales halladas en las ofitas del afloramiento de Trías de Estopiñán (Hesca) y se discute su significado en relación con la polaridad, la edad y el modo de emplazamiento de estas rocas

Observaciones petrográficas y tectónicas sobre las ofitas del área de Aulet (Prepirineo meridional, prov. de Huesca)

Se describen las diversas facies petrográficas y se indica su distribución en dos de las masas ofíticas del afloramiento de materiales triásicos de los alrededores de Aulet (Huesca). Se expresa su composición quimica que refleja elevada uniformidad y escasa diferenciación, mostrando analogía con los basaltos toleíticos continentales. Se ratifica su edad (Keuper-Lías) por el método óptico de la dispersión de la birrefringencia (Kd) y se adjunta una breve exposición de los fundamentos del método. Finalmente se analiza la fracturación y su comportamiento en relación con las deformaciones que afectan a la cobertera supratriásica

Classes of behavior of small-world networks

Small-world networks are the focus of recent interest because they appear to circumvent many of the limitations of either random networks or regular lattices as frameworks for the study of interaction networks of complex systems. Here, we report an empirical study of the statistical properties of a variety of diverse real-world networks. We present evidence of the occurrence of three classes of small-world networks: (a) scale-free networks, characterized by a vertex connectivity distribution that decays as a power law; (b) broad-scale networks, characterized by a connectivity distribution that has a power-law regime followed by a sharp cut-off; (c) single-scale networks, characterized by a connectivity distribution with a fast decaying tail. Moreover, we note for the classes of broad-scale and single-scale networks that there are constraints limiting the addition of new links. Our results suggest that the nature of such constraints may be the controlling factor for the emergence of different classes of networks

Environmental impact reduction of precast multi-storey buildings by crescent-moon seismic dampers hidden in beam-column joints

The growing demand of sustainable precast structures for multi-storey con-structions is often driven by the optimisation of cross-sections and reinforcement volumes of the structural elements. The present paper describes a real building recently designed and assembled with the installation of crescent-moon hysteretic dampers in the beam-column joints, recently proposed and patented. The joint continuity allows for an optimisation of the lateral load resist-ing system, reducing the size of the columns with respect to the classical precast frame structural arrangement with hinged joints, whilst protecting columns and beams from the large actions deriving from the classical moment-resisting cast-in-situ or partially precast technological solu-tions. After the complete detailed design of the case study building employing the 3 solutions described above, the precast dissipative one being designed with dynamic non-linear analysis, the results of an environmental impact analysis are compared and discussed, confirming a reduced environmental impact for the dissipative solution, with respect to both precast with hinged beam-column joints and moment-resisting cast-in-situ alternatives

Synchronizing Sequencing Software to a Live Drummer

Copyright 2013 Massachusetts Institute of Technology. MIT allows authors to archive published versions of their articles after an embargo period. The article is available at

Petrology of the Maladeta granitoids ln the Tahüll-Lago Negro sector (Lérida)

[Resumen] El Macizo plutónico de La Maladeta (Huesca-Lérida) corresponde, en su sector central (Tahül1-lago Negro), a un plutón circunscrito, cuyo carácter polifásico, está representado por los cuatro pulsos siguientes: a) los Cuarzo-Gabros, ubicados en su extremo sur, b) las Granodioritas que, con contenidos variables en anfíbol y biotita, comprenden, en conjunto, el volumen dominante y el pulso más representativo, c) las tonalitas con alto contenido en biotita y, por último, d) los sienogranitos (de dos micas) situados en su zona más central. La composición modal y, en especial, el análisis químico de las fases minerales principales (piroxeno, anfíbol, plagioclasa, biotita, moscovita y feldespato) corroboran una evolución magmática gradual, desde las composiciones más indiferenciadas (Cuarzo-Gabros) hasta las más tardías (Sienogranitos). Se observa una buena correspondencia entre la evolución petrologica (a nivel espacia!) y la de composición mineral, obtenidas por nosotros, con la secuencia de edades radiométicas (Rb/ Sr y U/Pb) determinadas por MICHARD-VITRAC, A. el al, (1980). Esta zonación tiene, a su vez, una muy buena correspondencia con las pautas de evolución geoquímica (elementos mayores y trazas) obtenidas en estudios preliminares (ARRANZ, E., 1991; ARRANZ, E. el al., 1991 a, by c).[Abstract] The Maladeta plutonic Massif (Huesca-Lérida) corresponds, in its central area (Tahül1-Lago Negro), to a circumscribed pluton wich, with multiepisodic character, is represented by the fol1owing four pulses: a) the Quartz-Gabbros, located in its southern extreme brim, b) the Granodiorites that, with variable amount in amphibole and biotite, consist, as a whole, the dominant volume and the most representative pulse, c) the biotite-rich Tonalites and, lastly, d) the syenogranites (with two micas), located in its centermost point. The modal composition and, special1y, the chemical analysis in main mineral phases (pyroxene, amphibole, plagioclase, biotite, muscovite, and feldspar), confirm a gradual magmatic evolution, from' a more indifferentiate composition (Quartz-Gabbross) to the latest (Syenogranites). There exists a good correspondence between the petrological and mineralogical composition, obtained by us, with the sequence of radiometric dates (Rb/Sr and U/Pb) analysed by MICHARD-VITRAC el al., (1980). The petrological zonation has, in turn, a very good correspondence with the pattern of magmatic evolution (major and trace elements) obtained in preliminary studies (ARRANZ, E., 1991; ARRANZ, E. el al., 1991 a, b y c)