Shaping electron wave functions in a carbon nanotube with a parallel magnetic field

A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here we demonstrate experimentally and theoretically that in carbon nanotube quantum dots, combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17T) magnetic fields in our experiment the wave functions can be tuned all the way from "half-wave resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape, with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with nontrivial lattice and topology.Comment: 5 figure

Short- and long-lasting tinnitus relief induced by transcranial direct current stimulation

A significant proportion of the population suffers from tinnitus, a bothersome auditory phantom perception that can severely alter the quality of life. Numerous experimental studies suggests that a maladaptive plasticity of the auditory and limbic cortical areas may underlie tinnitus. Accordingly, repetitive transcranial magnetic stimulation (rTMS) has been repeatedly used with success to reduce tinnitus intensity. The potential of transcranial direct current stimulation (tDCS), another promising method of noninvasive brain stimulation, to relieve tinnitus has not been explored systematically. In a double-blind, placebo-controlled and balanced order design, 20 patients suffering from chronic untreatable tinnitus were submitted to 20 minutes of 1 mA anodal, cathodal and sham tDCS targeting the left temporoparietal area. The primary outcome measure was a change in tinnitus intensity or discomfort assessed with a Visual Analogic Scale (VAS) change-scale immediately after tDCS and 1 hour later. Compared to sham tDCS, anodal tDCS significantly reduced tinnitus intensity immediately after stimulation; whereas cathodal tDCS failed to do so. The variances of the tinnitus intensity and discomfort VAS change-scales increased dramatically after anodal and cathodal tDCS, whereas they remained virtually unchanged after sham tDCS. Moreover, several patients unexpectedly reported longer-lasting effects (at least several days) such as tinnitus improvement, worsening, or changes in tinnitus features, more frequently after real than sham tDCS. Anodal tDCS is a promising therapeutic tool for modulating tinnitus perception. Moreover, both anodal and cathodal tDCS seem able to alter tinnitus perception and could, thus, be used to trigger plastic changes

Racialized Architectural Space: A Critical Understanding of its Production, Perception and Evaluation

Academic inquiry into the concept of space as racialized can be traced back to at least as far as the turn of the twentieth century with sociologist W. E. B. Dubois’ promulgation of the “color-line” theory. More recently, numerous postmodern scholars from a variety of fields have elucidated the various ways in which physical space (i.e., the built environment), as a social product, embodies racialized ideologies exhibited and reproduced by segregation, economics and other social practices. The dialogue on race and space has primarily been limited to the urban scales of city, neighborhood, community and street. Socio-spatial research that centers around race rarely addresses this phenomenon at the scale of architecture – the individual building or a particular development. Such a failure to critically examine the role of the architectural product in the creation and reproduction of socio-spatial and socio-racial inequality yields the field of architectural practice exempt and blameless in its tangible contribution to the psychosocial and geospatial marginalization of communities of color, as in, for example, the case of gentrification. This paper attempts to illustrate the fact that architecture, like all of the built physical environment, is not ahistorical, apolitical – and certainly not race neutral – but, as a social product, is also understood clearly within these contexts, and its psychological and social impacts and outcomes must be examined with a racially critical lens, particularly in heterogeneous urban communities