40 research outputs found
Magnetization Jump in a Model for Flux Lattice Melting at Low Magnetic Fields
Using a frustrated XY model on a lattice with open boundary conditions, we
numerically study the magnetization change near a flux lattice melting
transition at low fields. In both two and three dimensions, we find that the
melting transition is followed at a higher temperature by the onset of large
dissipation associated with the zero-field XY transition. It is characterized
by the proliferation of vortex-antivortex pairs (in 2D) or vortex loops (in
3D). At the upper transition, there is a sharp increase in magnetization, in
qualitative agreement with recent local Hall probe experiments.Comment: updated figures and texts. new movies available at
http://www.physics.ohio-state.edu:80/~ryu/jj.html. Accepted for publication
in Physical Review Letter
Nature of Phase Transitions of Superconducting Wire Networks in a Magnetic Field
We study - characteristics of periodic square Nb wire networks as a
function of temperature in a transverse magnetic field, with a focus on three
fillings 2/5, 1/2, and 0.618 that represent very different levels of
incommensurability. For all three fillings, a scaling behavior of -
characteristics is found, suggesting a finite temperature continuous
superconducting phase transition. The low-temperature - characteristics
are found to have an exponential form, indicative of the domain-wall
excitations.Comment: 5 pages, also available at
http://www.neci.nj.nec.com/homepages/tang.htm
Melting and transverse depinning of driven vortex lattices in the periodic pinning of Josephson junction arrays
We study the non-equilibrium dynamical regimes of a moving vortex lattice in
the periodic pinning of a Josephson junction array (JJA) for {\it finite
temperatures} in the case of a fractional or submatching field. We obtain a
phase diagram for the current driven JJA as a function of the driving current I
and temperature T. We find that when the vortex lattice is driven by a current,
the depinning transition at and the melting transition at
become separated even for a field for which they coincide in equilibrium. We
also distinguish between the depinning of the vortex lattice in the direction
of the current drive, and the {\it transverse depinning} in the direction
perpendicular to the drive. The transverse depinning corresponds to the onset
of transverse resistance in a moving vortex lattice at a given temperature
. For driving currents above the critical current we find that the
moving vortex lattice has first a transverse depinning transition at low T, and
later a melting transition at a higher temperature, .Comment: 17 pages, 19 figure
Grasping isoluminant stimuli
We used a virtual reality setup to let participants grasp discs, which differed in luminance, chromaticity and size. Current theories on perception and action propose a division of labor in the brain into a color proficient perception pathway and a less color-capable action pathway. In this study, we addressed the question whether isoluminant stimuli, which provide only a chromatic but no luminance contrast for action planning, are harder to grasp than stimuli providing luminance contrast or both kinds of contrast. Although we found that grasps of isoluminant stimuli had a slightly steeper slope relating the maximum grip aperture to disc size, all other measures of grip quality were unaffected. Overall, our results do not support the view that isoluminance of stimulus and background impedes the planning of a grasping movement
Similarities between digits’ movements in grasping, touching and pushing
In order to find out whether the movements of single digits are controlled in a special way when grasping, we compared the movements of the digits when grasping an object with their movements in comparable single-digit tasks: pushing or lightly tapping the same object at the same place. The movements of the digits in grasping were very similar to the movements in the single-digit tasks. To determine to what extent the hand transport and grip formation in grasping emerges from a synchronised motion of individual digits, we combined movements of finger and thumb in the single-digit tasks to obtain hypothetical transport and grip components. We found a larger peak grip aperture earlier in the movement for the single-digit tasks. The timing of peak grip aperture depended in the same way on its size for all tasks. Furthermore, the deviations from a straight line of the transport component differed considerably between subjects, but were remarkably similar across tasks. These results support the idea that grasping should be regarded as consisting of moving the digits, rather than transporting the hand and shaping the grip
A clinical review of the treatment of catatonia
Catatonia is a severe motor syndrome with an estimated prevalence among psychiatric inpatients of about 10%. At times, it is life-threatening especially in its malignant form when complicated by fever and autonomic disturbances. Catatonia can accompany many different psychiatric illnesses and somatic diseases. In order to recognize the catatonic syndrome, apart from thorough and repeated observation, a clinical examination is needed. A screening instrument, such as the Bush-Francis Catatonia Rating Scale, can guide the clinician through the neuropsychiatric examination. Although severe and life-threatening, catatonia has a good prognosis. Research on the treatment of catatonia is scarce, but there is overwhelming clinical evidence of the efficacy of benzodiazepines, such as lorazepam, and electroconvulsive therapy
Diagonal Cero - Número 27
Textos:
Algunas consideraciones sobre el tema escritura e imagen, por Reinhard Döhl
Luigi Ferro, Por Salvador Presta.
Trabajos plásticos
Franz Mon.
Luigi Ferro.
Edgardo Vigo.Centro de Arte Experimental Vig
Diagonal Cero - Número 27
Textos:
Algunas consideraciones sobre el tema escritura e imagen, por Reinhard Döhl
Luigi Ferro, Por Salvador Presta.
Trabajos plásticos
Franz Mon.
Luigi Ferro.
Edgardo Vigo.Centro de Arte Experimental Vig