Using visual design experts in critique-based evaluation of 2D vector visualization methods

We describe an experiment in which art and illustration experts evaluated six 2D vector visualization methods. We found that these expert critiques mirrored previously recorded experimental results; these findings support that using artists, visual designers and illustrators to critique scientific visualizations can be faster and more productive than quantitative user studies. Our participants successfully evaluated how well the given methods would let users complete a given set of tasks. Our results show a statistically significant correlation with a previous objective study: designers' subjective predictions of user performance by these methods match users measured performance. The experts improved the evaluation by providing insights into the reasons for the effectiveness of each visualization method and suggesting specific improvements.     

Scientific sketching for collaborative VR visualization design

We present four studies investigating tools and methodologies for artist-scientist-technologist collaboration in designing multivariate, virtual reality (VR) visualizations. Design study 1 identifies the promise of 3D drawing-style interfaces for VR design and also establishes limitations of these tools with respect to precision and support for animation. Design study 2 explores animating artist-created visualization designs with scientific 3D fluid flow data. While results captured an accurate sense of flow that was advantageous as compared to the results of study 1, the potential for visual exploration using the design tools tested was limited. Design study 3 reveals the importance of a new 3D interface that overcomes the precision limitation found in study 1 while remaining accessible to artist collaborators. Drawing upon previous results, design study 4 engages collaborative teams in a design process that begins with traditional paper sketching and moves to animated, interactive, VR prototypes "sketched" by designers in VR using interactive 3D tools. Conclusions from these four studies identify important characteristics of effective artist-accessible VR visualization design tools and lead to a proposed formalized methodology for successful collaborative design that we expect to be useful in guiding future collaborations. We call this proposed methodology Scientific Sketching.     

Interactive volume exploration for feature detection and quantification in industrial CT data

This paper presents a novel method for interactive exploration of industrial CT volumes such as cast metal parts, with the goal of interactively detecting, classifying, and quantifying features using a visualization-driven approach. The standard approach for defect detection builds on region growing, which requires manually tuning parameters such as target ranges for density and size, variance, as well as the specification of seed points. If the results are not satisfactory, region growing must be performed again with different parameters. In contrast, our method allows interactive exploration of the parameter space, completely separated from region growing in an unattended pre-processing stage. The pre-computed feature volume tracks a feature size curve for each voxel over time, which is identified with the main region growing parameter such as variance. A novel 3D transfer function domain over (density, feature size, time) allows for interactive exploration of feature classes. Features and feature size curves can also be explored individually, which helps with transfer function specification and allows coloring individual features and disabling features resulting from CT artifacts. Based on the classification obtained through exploration, the classified features can be quantified immediately.     

Resonance Raman and optical transient studies on the light-induced proton pump of bacteriorhodopsin reveal parallel photocycles

The photocycle of bacteriorhodopsin (bR) was studied at ambient temperature in aqueous suspensions of purple membranes using time-resolved resonance Raman (RR) and optical transient spectroscopy (OTS). The samples were photolyzed, and the fractional concentrations of the retinylidene chromophore in its parent state, BR570, and in the intermediate states L550, M412, N560, and O640 were determined in the time domain 20 microseconds-1 s and in the pH range 4-10.5. Two kinetically different L components could be identified. At pH 7 one fraction of L (approximately 65%) decays in 80 microseconds to M (deprotonation of the Schiff base), whereas the residual part is converted in approximately 0.5 ms to N. The RR spectra reveal only minor structural changes of the chromophore in the L-->N transition. These were attributed to a conformational change of the protein backbone [Ormos, P., Chu, K., & Mourant, J. (1992) Biochemistry 31, 6933]. With decreasing pH the L-->N transition is delayed to > 2 ms following a titration-like function with pKa approximately 6.2. The decay of M412 monitored by OTS can be fitted for each pH value by two different amplitudes and time constants (Mf, tau f; Ms, tau s; f = fast, s = slow). Both Mf and Ms consist of subcomponents which can be distinguished by their different reaction pathways (but not by OTS). Mf occurs in the reaction sequences L-->Mf-->N-->BR and L-->Mf-->O-->BR. The population of the first sequence, in which N is formed with the time constant tau f (approximately 2-4 ms, pH 6-10.5), increases with pH. Ms is also found in two different reaction sequences of the form L-->Ms-->BR. The quantitative analysis reveals that each "titration effect" can be related to a certain fraction of bR. It is proposed that each fraction can be identified with a "subspecies" of bR which undergoes an independent and individual cyclic reaction. A complete reaction scheme is set up which represents the manifold of observed phenomena. It is concluded from the pH dependence of the lifetimes of Ms and N that the reconstitution of BR570 in the reaction steps Ms-->BR and N-->BR requires the uptake of a proton from the external phase. It is argued that this proton catalyzes the reisomerization of retinal, whereas the Schiff base is internally reprotonated from Asp-85. A model for proton pumping is proposed in which the proton taken up from the external phase to catalyze the reisomerization of retinal is the one which is pumped through the membrane during the photocycle of bR.     

Learning Perceptrons and Piecewise Linear Classifiers Sensitive to Example Dependent Costs

This article considers the cost dependent construction of linear and piecewise linear classifiers. Classical learning algorithms from the fields of artificial neural networks and machine learning consider either no costs at all or allow only costs that depend on the classes of the examples that are used for learning. In contrast to class dependent costs, we consider costs that are example, i.e. feature and class dependent. We present a cost sensitive extension of a modified version of the well-known perceptron algorithm that can also be applied in cases, where the classes are linearly non-separable. We also present an extended version of the hybrid learning algorithm DIPOL, that can be applied in the case of linear non-separability, multi-modal class distributions, and multi-class learning problems. We show that the consideration of example dependent costs is a true extension of class dependent costs. The approach is general and can be extended to other neural network architectures like multi-layer perceptrons and radial basis function networks.     

A revision of the Job Diagnostic Survey: Elimination of a measurement artifact.

The dimensionality of the original Job Diagnostic Survey (JDS) and a revision were investigated. Factor analyses of two data sets identified six dimensions underlying the original JDS. Five of the factors correspond to the pattern expected for the JDS items; the sixth was identified as a measurement artifact. Five of the JDS items were subsequently rewritten to eliminate the artifact. The revised survey was administered to employees of a printing company (N?=?134) and the a priori five-factor solution was obtained with no artifact factor. Scale–factor correlations were also computed. The resulting coefficients suggest that the revised JDS scales are measuring their underlying constructs with reasonable accuracy. As a result of the measurement artifact in the original JDS, it is recommended that the revised JDS should be used in future research concerned with task characteristics. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal course of perfusion in human masseter muscle during isometric contraction assessed by arterial spin labeling at 3T

Object  

Examination of blood perfusion in the masseter muscle in the course of repetitive isometric contraction by arterial spin-labeling (ASL) MR imaging and additional T2 relaxation time measurements during and after masseter muscle activation.     

Proton incorporation in yttria-stabilized zirconia during atomic layer deposition

This work elucidated the proton-incorporation mechanism in ALD YSZ¹. Isotope ²H₂O was used as an oxidant to trace proton incorporation. The ratio of ZrO₂ to Y₂O₃ ALD cycles was varied from 1:1 to 5:1. TEM confirmed that the ALD YSZ films grew as fully crystallized columnar grains in the cubic ZrO₂ phase. SIMS indicated that the Y³⁺ and ²H⁺ concentrations were linearly correlated, indicating yttria-deposition-induced proton incorporation. XPS confirmed an appreciable amount of Y(OH)₃ proportional to the ²H⁺ content in the ALD YSZ, as was also detected by SIMS. Oxide ion vacancies created by the replacement of ZrO₂ with relatively small amounts of Y₂O₃ provided additional vacancies for proton incorporation, resulting in steeper [²H⁺]/[Y³⁺] slopes.