Attention does not affect multisensory cue weighting

Humans gather information about their environment from multiple sensory channels. It seems that cues from separate sensory modalities (e.g., vision and haptics) are combined in a statistically optimal way according to a maximum-likelihood estimator (Ernst Banks, 2002). Ernst and Banks showed that for bi-modal perceptual estimates, the weight attributed to one sensory channel changes when its relative reliability is modified by increasing the noise associated to its signal. Here we address the question as to whether selectively increasing the attentional load of one sensory channel does affect the weighting of cues from different sensory channels. In our experiment, subjects’ main-task was to estimate the size of a raised bar using vision alone, haptics alone, or both modalities combined. Their performance in the main-task condition alone is compared to the performance obtained when a concurrent visual ‘distractor’-task is performed. We found that vision-based estimates are more affected by a visual ‘distractor’ than the haptics-based estimates. Thus, attention is indeed selectively detracted from the visual modality. Moreover, we found that the cue weighting is not affected by adding the visual ‘distractor’-task. Therefore we can conclude that multisensory integration occurs at an early stage of processing and is not affected by attention

Elastic moduli approximation of higher symmetry for the acoustical properties of an anisotropic material

The issue of how to define and determine an optimal acoustical fit to a set of anisotropic elastic constants is addressed. The optimal moduli are defined as those which minimize the mean squared difference in the acoustical tensors between the given moduli and all possible moduli of a chosen higher material symmetry. The solution is shown to be identical to minimizing a Euclidean distance function, or equivalently, projecting the tensor of elastic stiffness onto the appropriate symmetry. This has implications for how to best select anisotropic constants to acoustically model complex materials.Comment: 20 page

Channel Plate Detection in Low Energy Scanning Electron Microscopy

Microchannel plate (MCP) electron detectors compare favorably with the Everhart-Thornley detector for producing SEM images from both secondary and back-scattered electrons. The MCP is a compact array of 105 - 106 channel electron multipliers with a gain in excess of 106 and the collective ability to count ~ 108 electrons per second. The MCP can be mounted coaxially with the beam allowing un-tilted sample orientation and electron collection into a large, field-free solid angle. The speed and low noise of the MCP allow images to be made in less than one second at moderate beam currents or in longer times with very low beam currents. Because of the wide detection angle, images from coaxially located MCP\u27s show little loss of detail due to shadowing but by the same token are peculiarly flat in appearance. This suggests that they might usefully complement another detector in many applications. Lifetime data are still limited, but the detectors used for this report show no noticeable deterioration with well over 100 hours of use

Silicone-Induced Granuloma after Injection for Cosmetic Purposes: A Rare Entity of Calcitriol-Mediated Hypercalcemia

Hypercalcemia is often a clue to the presence of unsuspected illness. We present an interesting case of an HIV-positive transgender female with a rare cause of silicone-induced granulomatous hypercalcemia. Although there have been a few case reports of silicone injections in dialysis patients causing hypercalcemia, this metabolic derangement secondary to silicone granulomas continues to be a unique entity with an unclear pathophysiology. We present a 45-year-old transgender HIV-positive female, with extensive silicone injections who presented with symptomatic hypercalcemia. Workup for malignancy and hyperparathyroidism was negative. 1,25-Dihydroxyvitamin D level and 24-hour urine calcium level were elevated. CT scan showed extensive high-density reticulonodular densities in the buttocks and gluteal muscle fascia extending upwards to the lumbar region, along with prominent external iliac and inguinal lymph nodes. Nuclear imaging showed diffuse heterogeneity and increased uptake in the buttocks, most consistent with granuloma calcifications, and an inguinal lymph node biopsy confirmed a foreign body giant cell reaction. The patient was started on prednisone and this resulted in decrease in serum and urinary calcium levels. Physicians should have a high index of suspicion for silicone-induced hypercalcemia considering the growing prevalence of body contour enhancement with injections, implants, and fillers using this material

MEVA - An interactive visualization application for validation of multifaceted meteorological data with multiple 3D devices

To achieve more realistic simulations, meteorologists develop and use models with increasing spatial and temporal resolution. The analyzing, comparing, and visualizing of resulting simulations becomes more and more challenging due to the growing amounts and multifaceted character of the data. Various data sources, numerous variables and multiple simulations lead to a complex database. Although a variety of software exists suited for the visualization of meteorological data, none of them fulfills all of the typical domain-specific requirements: support for quasi-standard data formats and different grid types, standard visualization techniques for scalar and vector data, visualization of the context (e.g., topography) and other static data, support for multiple presentation devices used in modern sciences (e.g., virtual reality), a user-friendly interface, and suitability for cooperative work

Dark Energy and the Statistical Study of the Observed Image Separations of the Multiply Imaged Systems in the CLASS Statistical Sample

The present day observations favour a universe which is flat, accelerated and composed of $\sim 1/3$ matter (baryonic + dark) and $\sim 2/3$ of a negative pressure component, usually referred to as dark energy or quintessence. The Cosmic Lens All Sky Survey (CLASS), the largest radio-selected galactic mass scale gravitational lens search project to date, has resulted in the largest sample suitable for statistical analyses. In the work presented here, we exploit observed image separations of the multiply imaged lensed radio sources in the sample. We use two different tests: (1) image separation distribution function $n(\Delta\theta)$ of the lensed radio sources and (2) {\dtheta}_{\mathrm{pred}} vs {\dtheta}_{\mathrm{obs}} as observational tools to constrain the cosmological parameters $w$ and \Om. The results are in concordance with the bounds imposed by other cosmological tests.Comment: 20 pages latex; Modified " Results and Discussion " section, new references adde

Poly-MTO, {(CH_3)_{0.92} Re O_3}_\infty, a Conducting Two-Dimensional Organometallic Oxide

Polymeric methyltrioxorhenium, {(CH_{3})_{0.92}ReO_{3}}_{\infty} (poly-MTO), is the first member of a new class of organometallic hybrids which adopts the structural pattern and physical properties of classical perovskites in two dimensions (2D). We demonstrate how the electronic structure of poly-MTO can be tailored by intercalation of organic donor molecules, such as tetrathiafulvalene (TTF) or bis-(ethylendithio)-tetrathiafulvalene (BEDT-TTF), and by the inorganic acceptor SbF$_3$. Integration of donor molecules leads to a more insulating behavior of poly-MTO, whereas SbF$_3$ insertion does not cause any significant change in the resistivity. The resistivity data of pure poly-MTO is remarkably well described by a two-dimensional electron system. Below 38 K an unusual resistivity behavior, similar to that found in doped cuprates, is observed: The resistivity initially increases approximately as $\rho \sim$ ln$(1/T$) before it changes into a $\sqrt{T}$ dependence below 2 K. As an explanation we suggest a crossover from purely two-dimensional charge-carrier diffusion within the \{ReO$_2$\}$_{\infty}$ planes at high temperatures to three-dimensional diffusion at low temperatures in a disorder-enhanced electron-electron interaction scenario (Altshuler-Aronov correction). Furthermore, a linear positive magnetoresistance was found in the insulating regime, which is caused by spatial localization of itinerant electrons at some of the Re atoms, which formally adopt a $5d^1$ electronic configuration. X-ray diffraction, IR- and ESR-studies, temperature dependent magnetization and specific heat measurements in various magnetic fields suggest that the electronic structure of poly-MTO can safely be approximated by a purely 2D conductor.Comment: 15 pages, 16 figures, 2 table

Effect of attention on multimodal cue integration

Humans gather information about their environment from multiple sensory channels. It seems that cues from separate sensory modalities (e.g. vision and haptics) are combined in a statistically optimal way according to a maximum-likelihood estimator [1]. Ernst and Banks showed that for bi-modal perceptual estimates, the weight attributed to one sensory channel changes when its relative reliability is modified by increasing the noise associated to its signal. Because increasing the attentional load of a given sensory channel is likely to change its reliability, we assume that such modification would also alter the weight of the different cues for multimodal perceptual estimates. Here we examine this hypothesis using a dual-task paradigm. Subjects’ main-task is to estimate the size of a raised bar using vision alone, haptics alone, or both modalities combined. Their performance in the main-task condition alone is compared to the performance obtained when an additional visual ‘distractor’-task is performed simultaneously to the main-task (Dual-Task Paradigm). We found that vision-based estimates are more affected by a visual ‘distractor’ than the haptics-based estimates. Our findings substantiate that attention influences the weighting of the different sensory channels for multimodal perceptual estimates. That is, when attention is detracted from the visual modality, the haptic estimates are consequently weighted higher in visual-haptic size discrimination. In further experiments, we will examine the influence of a haptic ‘distractor’-task. We would expect, that a haptic ‘distractor’ interferes to a higher extend with the haptic primary task. The vision-based estimates in the main-task should be less affected. We will then further examine whether cue integration is still statistically optimal

Performance of the exact adiabatic density functional to describe Rabi physics

Trabajo presentado al American Physical Society Meeting, celebrado en Boston (US) del 27 de Febrero al 2 de Marzo de 2012.-- Título de la presentación: "Rabi oscillations within TDDFT: the example of the 2 site Hubbard model".Through the exact solution of few-electron systems interacting with a monochromatic laser we study the performance of adiabatic density functionals within time-dependent density-functional theory (TDDFT) to reproduce Rabi oscillations. The non-linear dynamics of the Kohn-Sham (KS) system shows the characteristic features of detuned Rabi oscillations even if the exact resonant frequency is used. We illustrate this effect by comparing the exact time-dependent many-body solution of a He-atom in one dimension and a few-site Hubbard model with the solution of TDDFT-KS equations for different adiabatic exchange-correlation functionals. Preventing the detuning introduces a new strong condition to be satisfied by approximate new xc-functionals.Peer reviewe

Time-dependent density-functional and reduced density-matrix methods for few electrons: Exact versus adiabatic approximations

To address the impact of electron correlations in the linear and non-linear response regimes of interacting many-electron systems exposed to time-dependent external fields, we study one-dimensional (1D) systems where the interacting problem is solved exactly by exploiting the mapping of the 1D $N$-electron problem onto an $N$-dimensional single electron problem. We analyze the performance of the recently derived 1D local density approximation as well as the exact-exchange orbital functional for those systems. We show that the interaction with an external resonant laser field shows Rabi oscillations which are detuned due to the lack of memory in adiabatic approximations. To investigate situations where static correlations play a role, we consider the time-evolution of the natural occupation numbers associated to the reduced one-body density matrix. Those studies shed light on the non-locality and time-dependence of the exchange and correlation functionals in time-dependent density and density-matrix functional theories.Comment: 19 pages, 13 figures, version as published apart from layou