Magnetism in Atomic-Sized Palladium Contacts and Nanowires

We have investigated Pd nanowires theoretically, and found that, unlike either metallic or free atomic Pd, they exhibit Hund's rule magnetism. In long, monoatomic wires, we find a spin moment of 0.7 Bohr magnetons per atom, whereas for short, monoatomic wires between bulk leads, the predicted moment is about 0.3 Bohr magnetons per wire atom. In contrast, a coaxial (6,1) wire was found to be nonmagnetic. The origin of the wire magnetism is analyzed.Comment: 6 pages, including 4 figure

Spontaneous Magnetization of Simple Metal Nanowires

On the basis of self-consistent density-functional calculations, it is predicted that three-dimensional nanowires of simple (nonmagnetic) metals undergo a transition to a spin-polarized magnetic state at critical radii. The magnetic transition also contributes to the elongation force on the nanowire. The force exhibits oscillations due to quantum confinement, in tune with the conductance steps as the wire is pulled.Peer reviewe

Electronic structure of cylindrical simple-metal nanowires in the stabilized jellium model

The ground-state electronic structures of cylindrical quantum wires are studied within the stabilized jellium model and using the spin-dependent density-functional theory. The subband structure is shown to affect the cohesive properties, causing an oscillating structure in the force needed to elongate the wire. Because the steps in the quantized conductance reflect also the subband structure a correlation between the force oscillations and conductance steps is established. The model also predicts magnetic solutions commensurate with the subband structure and consequently additional steps in the conductance.Peer reviewe

Analysis of the sporting context of Spanish female competitive cyclists and triathletes

El objetivo del presente estudio fue conocer y comparar las características psicosociales de las ciclistas y triatletas federadas en España estableciendo unas pautas de actuación que mejoren su situación en el deporte de competición. Se analizan dos deportes con aspectos comunes (uso de la bicicleta en competición, participantes que realizan ambos deportes…) y diferenciadores (deporte clásico vs deporte moderno), con el objeto de descubrir las posibles diferencias y/o similitudes entre ambos. En este estudio descriptivo participaron 80 ciclistas y 126 triatletas. Se determinó el perfil sociodemográfico promedio de las ciclistas y triatletas mediante 2 cuestionarios semiestructurados que permitieron definirlas como deportistas a) amateurs con tendencia competidora, b) iniciadas a una edad tardía en su especialidad deportiva, c) con una amplia experiencia deportiva, d) con un nivel alto de estudios completado o en curso, y e) pertenecientes a un estrato social medio. Tras el análisis de los resultados creemos que se hace necesario un cambio en la política deportiva de las federaciones deportivas así como iniciativas tendentes a la mejora de las condiciones de competición de estas deportistasThe aim of this study was to know and compare the psychosocial characteristics from Spanish under-licence female cyclists and triathletes establishing guidelines to improve their situation in competitive sport. We compared two sports with common aspects (use of a bicycle in competition, participants who participate in both sports...) and differentiating ones (classic sport vs. modern), with the aim of uncover potential differences and/or similarities between the two. 80 cyclists and 126 triathletes took part in this descriptive study. We determined the average socio-demographic profile of cyclists and triathletes through 2 semistructured questionnaires. The athletes’ average socio-sporting profile was defined as a) amateur with a competitive tendency; b) who became specialised in the sport at a late age; c) having vast sporting experience; d) having completed, or completing, a high level of education; e) belonging to the middle class. We believe a change in politics in sports federations is needed, as are initiatives to improve competition conditions for these athletesEstudio financiado por el Ministerio de Educación y ciencia (AP2009-0529) y por la Real Federación Española de Ciclism

Spontaneous magnetization of aluminum nanowires deposited on the NaCl(100) surface

We investigate electronic structures of Al quantum wires, both unsupported and supported on the (100) NaCl surface, using the density-functional theory. We confirm that unsupported nanowires, constrained to be linear, show magnetization when elongated beyond the equilibrium length. Allowing ions to relax, the wires deform to zig-zag structures with lower magnetization but no dimerization occurs. When an Al wire is deposited on the NaCl surface, a zig-zag geometry emerges again. The magnetization changes moderately from that for the corresponding unsupported wire. We analyse the findings using electron band structures and simple model wires.Comment: submitted to PHys. Rev.

Macrofauna de invertebrados del Cretácico superior de la Depresión Central Asturiana

Se reporta y comenta la fauna de inocerámidos, rudistas, ammonites, braquiópodos y equmnidos recogida y localizada en yacimientos o series estratigráficas de detalle, durante los trabajos de campo de la tesis doctoral del primero de los autores (E.B.) sobre los seláceos del Cretácico de Asturias. La distribución, principalmente de inocerámidos y ammonites, permite identificar el Cenomaniense superior y el Turoniense inferior y medio. Se han reconocido rudistas del Turoniense superior y del Coniaciense, braquiópodos del Cenomaniense y del Santoniense inferior y un registro relativamente rico y variado de equínidos desde el Cenomaniense hasta el Coniaciense.The fauna collected and located on fossil localities or stratigraphical profiles, during the field work of the first author's doctoral thesis on the Cretaceous selachians from Asturias, is reported and commented. It includes inoceramids, rudists, ammonoids, brachiopods and echinoids. Distribution of, mainly inoceramids and ammonoids, allowed to identify the Upper Cenomanian and the Lower and Middle Turonian. LateTuronian and Coniacian rudists have been recognized, as well as Cenomanian and lower Santonian brachiopods and a quite rich and diversified record of echinoids ranging from Cenomanian to Coniacian

Peripheral neuropathy caused by fenugreek (Trigonella foenum-graecum) straw intoxication in cattle and experimental reproduction in sheep and goats

Trigonella foenum-graecum (fenugreek) is a legume widely used as a food supplement in humans and less frequently in ruminants. Toxicity has been described sporadically in ruminants grazing mature fenugreek plants or stubble; however, the pathological features are unclear. This report describes a natural outbreak of intoxication in cattle fed fenugreek straw and the experimental reproduction using 8 sheep and 8 goats. Affected cattle presented clinical signs approximately 1 month after consuming the straw and 100 of 400 cattle (25%) were affected, of which 60 of 100 (60%) died or were euthanized. Clinical signs were characterized by proprioceptive positioning defects with abnormal postures and weakness of hindlimbs. Forelimbs were also affected in severely affected animals, and cattle became recumbent. Locomotion was characterized by trembling, and some cattle showed high-stepping movements of their forelimbs and knuckled over in their fetlocks. Experimental intoxication induced clinical signs only in sheep and were similar to cattle, although with signs starting in the forelegs. Gross and microscopic lesions were similar in spontaneous and experimental intoxications. Macroscopic changes corresponded with muscular hemorrhages and edema, mainly surrounding the peripheral nerves. Microscopic examination only demonstrated lesions in the distal peripheral nerves, which included edema, hemorrhages, and Wallerian degeneration. Neurofilament immunohistochemistry revealed altered axon labeling and S100 showed a decrease in myelin intensity and loss of its typical compact arrangement around axons. Biochemical and hematological abnormalities included elevated levels of muscle and liver enzymes and thrombocytopenia. These findings indicate that fenugreek straw induces peripheral neuropathy in cattle and sheep, but not in goats

Excited states of Na nanoislands on the Cu(111) surface

Electronic states of one monolayer high Na nanoislands on the Cu(111) surface are studied as a function of the nanoisland size. Properties of nanoislands such as one-electron states, the electron density, and the associated potential are obtained self-consistently within the density-functional formalism using a one-dimensional pseudopotential for the Cu(111) substrate and the jellium model for Na. A wave packet propagation method is used to study the energies and lifetimes of quasistationary states localized at Na islands. For very large islands, island-localized states merge into the two-dimensional continuum of the Na quantum well state. Thus, we assign the quasistationary states studied as arising from the quantization of the two-dimensional quantum well continuum due to the finite island size. The scattering at the island boundaries results in the energy-conserving resonant electron transfer into the continuum of the substrate states broadening the island-localized states into resonances.Peer reviewe

Model study of adsorbed metallic quantum dots: Na on Cu(111)

We model electronic properties of the second monolayer Na adatom islands (quantum dots) on the Cu(111) surface covered homogeneously by the first Na monolayer. An axially-symmetric three-dimensional jellium model, taking into account the effects due to the first Na monolayer and the Cu substrate, has been developed. The electronic structure is solved within the local-density approximation of the density-functional theory using a real-space multigrid method. The model enables the study of systems consisting of thousands of Na-atoms. The results for the local density of states are compared with differential conductance ($dI/dV$) spectra and constant current topographs from Scanning Tunneling Microscopy.Comment: 10 pages, 8 figures. For better quality figures, download http://www.fyslab.hut.fi/~tto/cylart1.pd