Multidimensional tactons for non-visual information presentation in mobile devices

Tactons are structured vibrotactile messages which can be used for non-visual information presentation when visual displays are limited, unavailable or inappropriate, such as in mobile phones and other mobile devices. Little is yet known about how to design them effectively. Previous studies have investigated the perception of Tactons which encode two dimensions of information using two different vibrotactile parameters (rhythm and roughness) and found recognition rates of around 70. When more dimensions of information are required it may be necessary to extend the parameter-space of these Tactons. Therefore this study investigates recognition rates for Tactons which encode a third dimension of information using spatial location. The results show that identification rate for three-parameter Tactons is just 48, but that this can be increased to 81 by reducing the number of values of one of the parameters. These results will aid designers to select suitable Tactons for use when designing mobile displays

A first investigation into the effectiveness of Tactons

This paper reports two experiments relating to the design of Tactons (or tactile icons). The first experiment investigated perception of vibro-tactile "roughness" (created using amplitude modulated sinusoids), and the results indicated that roughness could be used as a parameter for constructing Tactons. The second experiment is the first full evaluation of Tactons, and uses three values of roughness identified in the first experiment, along with three rhythms to create a set of Tactons. The results of this experiment showed that Tactons could be a successful means of communicating information in user interfaces, with an overall recognition rate of 71%, and recognition rates of 93% for rhythm and 80% for roughness

Tactile crescendos and sforzandos: applying musical techniques to tactile icon design

Tactile icons (Tactons) are structured vibrotactile messages which can be used for non visual information display. Information is encoded in Tactons by manipulating vibrotactile parameters. This research investigates the possibilities of applying musical techniques to tactile icon design in order to define such parameters. Tactile versions of musical dynamics were created by manipulating the amplitude of vibrations to create increasing, decreasing, and level stimuli and an experiment was carried out to test perception of these stimuli. Identification rates of 92%-100% indicate that these tactile dynamics can be identified and distinguished from each other, and that tactile dynamics could be used in Tacton design

Properties of visual field defects around the monocular preferred retinal locus in age-related macular degeneration

YesPURPOSE. To compare microperimetric sensitivity around the monocular preferred retinal locus (mPRL) in age-related macular degeneration (AMD) to normative data, and to describe the characteristics of visual field defects around the mPRL in AMD. METHODS. Participants with AMD (total n ¼ 185) were either prospectively recruited (n ¼ 135) or retrospectively reviewed from an existing database (n ¼ 50). Participants underwent microperimetry using a test pattern (37 point, 58 radius) centered on their mPRL. Sensitivities were compared to normative data by spatial interpolation, and conventional perimetric indices were calculated. The location of the mPRL relative to the fovea and to visual field defects was also investigated. RESULTS. Location of mPRL varied approximately 158 horizontally and vertically. Visual field loss within 58 of the mPRL was considerable in the majority of participants (median mean deviation 14.7 dB, interquartile range [IQR] 19.6 to 9.6 dB, median pattern standard deviation 7.1 dB [IQR 4.8–9.0 dB]). Over 95% of participants had mean total deviation worse than 2 dB across all tested locations and similarly within 18 of their mPRL. A common pattern of placing the mPRL just foveal to a region of normal pattern deviation was found in 78% of participants. Total deviation was outside normal limits in this region in 68%. CONCLUSIONS. Despite altering fixation to improve vision, people with AMD exhibit considerable visual field loss at and around their mPRL. The location of the mPRL was typically just foveal to, but not within, a region of relatively normal sensitivity for the individual, suggesting that a combination of factors drives mPRL selection.This report presents independent research funded by the NIH

Dilepton Production in Nucleon-Nucleon Interactions

Starting from a realistic one--boson--exchange--model fitted to the amplitudes of elastic nucleon--nucleon scattering and the process $NN\rightarrow N\Delta$ we perform a fully relativistic and gauge invariant calculation for the dilepton production in nucleon--nucleon collisions, including the important effect of propagating the $\Delta$--resonance. We compare the results of our calculations with the latest experimental data on dilepton production. We also show how to implement various electromagnetic formfactors for the hadrons in our calculations without loosing gauge--invariance and discuss their influence on dilepton spectra.Comment: 24 pages, figures will be sent on reques

Autocorrelation in Updating Pure SU(3) Lattice Gauge Theory by the use of Overrelaxed Algorithms

We measure the sweep-to-sweep autocorrelations of blocked loops below and above the deconfinement transition for SU(3) on a $16^4$ lattice using 20000-140000 Monte-Carlo updating sweeps. A divergence of the autocorrelation time toward the critical $\beta$ is seen at high blocking levels. The peak is near $\beta$ = 6.33 where we observe 440 $\pm$ 210 for the autocorrelation time of $1\times 1$ Wilson loop on $2^4$ blocked lattice. The mixing of 7 Brown-Woch overrelaxation steps followed by one pseudo-heat-bath step appears optimal to reduce the autocorrelation time below the critical $\beta$. Above the critical $\beta$, however, no clear difference between these two algorithms can be seen and the system decorrelates rather fast.Comment: 4 pages of A4 format including 6-figure

Fluid Models of Many-server Queues with Abandonment

We study many-server queues with abandonment in which customers have general service and patience time distributions. The dynamics of the system are modeled using measure- valued processes, to keep track of the residual service and patience times of each customer. Deterministic fluid models are established to provide first-order approximation for this model. The fluid model solution, which is proved to uniquely exists, serves as the fluid limit of the many-server queue, as the number of servers becomes large. Based on the fluid model solution, first-order approximations for various performance quantities are proposed

The runaway binary LP 400-22 is leaving the Galaxy

We present optical spectroscopy, astrometry, radio and X-ray observations of the runaway binary LP 400-22. We refine the orbital parameters of the system based on our new radial velocity observations. Our parallax data indicate that LP 400-22 is significantly more distant (3σ lower limit of 840pc) than initially predicted. LP 400-22 has a tangential velocity in excessof 830 km s-1; it is unbound to the Galaxy. Our radio and X-ray observations fail to detect a recycled millisecond pulsar companion, indicating that LP 400-22 is a double white dwarf system. This essentially rules out a supernova runaway ejection mechanism. Based on its orbit, a Galactic Centre origin is also unlikely. However, its orbit intersects the locations of several globular clusters; dynamical interactions between LP 400-22 and other binary stars or a central black hole in a dense cluster could explain the origin of this unusual binary.Instituto de Astrofísica de La Plat

Transport in rough self-affine fractures

Transport properties of three-dimensional self-affine rough fractures are studied by means of an effective-medium analysis and numerical simulations using the Lattice-Boltzmann method. The numerical results show that the effective-medium approximation predicts the right scaling behavior of the permeability and of the velocity fluctuations, in terms of the aperture of the fracture, the roughness exponent and the characteristic length of the fracture surfaces, in the limit of small separation between surfaces. The permeability of the fractures is also investigated as a function of the normal and lateral relative displacements between surfaces, and is shown that it can be bounded by the permeability of two-dimensional fractures. The development of channel-like structures in the velocity field is also numerically investigated for different relative displacements between surfaces. Finally, the dispersion of tracer particles in the velocity field of the fractures is investigated by analytic and numerical methods. The asymptotic dominant role of the geometric dispersion, due to velocity fluctuations and their spatial correlations, is shown in the limit of very small separation between fracture surfaces.Comment: submitted to PR

Unstable particles in matter at a finite temperature: the rho and omega mesons

Unstable particles (such as the vector mesons) have an important role to play in low mass dilepton production resulting from heavy ion collisions and this has been a subject of several investigations. Yet subtleties, such as the implications of the generalization of the Breit-Wigner formula for nonzero temperature and density, e.g. the question of collisional broadening, the role of Bose enhancement, etc., the possibility of the kinematic opening (or closing) of decay channels due to environmental effects, the problem of double counting through resonant and direct contributions, are often given insufficient emphasis. The present study attempts to point out these features using the rho and omega mesons as illustrative examples. The difference between the two versions of the Vector Meson Dominance Model in the present context is also presented. Effects of non-zero temperature and density, through vector meson masses and decay widths, on dilepton spectra are studied, for concreteness within the framework of a Walecka-type model, though most of the basic issues highlighted apply to other scenarios as well.Comment: text and figures modifie