Layout of Multiple Views for Volume Visualization: A User Study

Abstract. Volume visualizations can have drastically different appearances when viewed using a variety of transfer functions. A problem then occurs in trying to organize many different views on one screen. We conducted a user study of four layout techniques for these multiple views. We timed participants as they separated different aspects of volume data for both time-invariant and time-variant data using one of four different layout schemes. The layout technique had no impact on performance when used with time-invariant data. With time-variant data, however, the multiple view layouts all resulted in better times than did a single view interface. Surprisingly, different layout techniques for multiple views resulted in no noticeable difference in user performance. In this paper, we describe our study and present the results, which could be used in the design of future volume visualization software to improve the productivity of the scientists who use it

The life history and ecology of Bluefish, Girella cyanea, at Lord Howe Island

University of Technology, Sydney. Faculty of Science.Girella cyanea is a conspicuous member of the reef-fish community in the Lord Howe Island Marine Park (LHIMP), but very little is known about its life history. Rareness of this species on mainland Australian coasts in recent years has initiated a fishing ban across the state of New South Wales, however recreational fishing is still permitted on LHI. Effective management and conservation of this population requires increased information on life history and demographics. Management currently in place for this species is limited. A bag limit of 5 fish person-1 day-1 is imposed in habitat protection zones across the Marine Park. It is difficult to measure the effectiveness of this strategy, however, without the knowledge of the resource requirements of the species and how these may change throughout the course of life. This study aimed to describe distribution, diet and growth in G. cyanea to provide important information for best-practice management of the LHI population. An extensive literature search was conducted for published life history, ecology and management data on Girellidae, revealing relatively scarce information for the family. A pilot study assessed the utility of a roaming survey method towing a GPS-receiver behind an observer on snorkel/SCUBA. This new method proved effective and was used for size-based assessments of habitat-use at nearshore and offshore locations around the LHI archipelago. Densities of G. cyanea were highest in complex rocky intertidal and rocky-reef areas. Dietary analyses helped explain this distribution, with gut contents showing intertidal green algal species (i.e. Ulva and Enteromorpha) are important food resources for post-settlement fish. An ontogenetic dietary shift was found, with fish 40 mm Ls and diets exhibited increased ingestion of algae. Age-at-size using otoliths and von Bertalanffy parameters revealed G. cyanea is fast-growing and long-lived (up to 41 yrs). It is likely the transition to sexual maturity occurs between 2 and 5 years of age or 200 mm Ls. Size-based observations place fish of this life stage within complex rock habitats at depths < 5 m. Future management policies should ensure adequate (representative) areas of rocky intertidal habitat are within sanctuary zoning to protect G. cyanea at this important life stage

Are joint torque models limited by an assumption of monoarticularity?

This study determines whether maximal voluntary ankle plantar flexor torque could be more accurately represented using a torque generator that is a function of both knee and ankle kinematics. Iso velocity and isometric ankle plantar flexor torques were measured on a single participant for knee joint angles of 111° to 169° (approximately full extension) using a Contrex M J dynamometer. Maximal voluntary torque was represented by a 19-parameter two-joint function of ankle and knee joint angles and angular velocities with the parameters determined by minimizing a weighted root mean square difference between measured torques and the two-joint function. The weighted root mean square difference between the two-joint function and the measured torques was 10 N-m or 3% of maximum torque. The two-joint function was a more accurate representation of maximal voluntary ankle plantar flexor torques than an existing single-joint function where differences of 19% of maximum torque were found. It is concluded that when the knee is flexed by more than 40°, a two-joint representation is necessary

An isovelocity dynamometer method to determine monoarticular and biarticular muscle parameters

This study aimed to determine whether subject-specific individual muscle models for the ankle plantar flexors could be obtained from single joint isometric and isovelocity maximum torque measurements in combination with a model of plantar flexion. Maximum plantar flexion torque measurements were taken on one subject at six knee angles spanning full flexion to full extension. A planar three-segment (foot, shank and thigh), two muscle (soleus and gastrocnemius) model of plantar flexion was developed. Seven parameters per muscle were determined by minimizing a weighted root mean square difference (wRMSD) between the model output and the experimental torque data. Valid individual muscle models were obtained using experimental data from only two knee angles giving a wRMSD score of 16 N m, with values ranging from 11 to 17 N m for each of the six knee angles. The robustness of the methodology was confirmed through repeating the optimization with perturbed experimental torques (±20%) and segment lengths (±10%) resulting in wRMSD scores of between 13 and 20 N m. Hence, good representations of maximum torque can be achieved from subject-specific individual muscle models determined from single joint maximum torque measurements. The proposed methodology could be applied to muscle-driven models of human movement with the potential to improve their validity

The Nature of the Chemical Process. 1. Symmetry Evolution - Revised Information Theory, Similarity Principle and Ugly Symmetry

Three laws of information theory have been proposed. Labeling by introducing nonsymmetry and formatting by introducing symmetry are defined. The function L (L=lnw, w is the number of microstates, or the sum of entropy and information, L=S+I) of the universe is a constant (the first law of information theory). The entropy S of the universe tends toward a maximum (the second law law of information theory). For a perfect symmetric static structure, the information is zero and the static entropy is the maximum (the third law law of information theory). Based on the Gibbs inequality and the second law of the revised information theory we have proved the similarity principle (a continuous higher similarity-higher entropy relation after the rejection of the Gibbs paradox) and proved the Curie-Rosen symmetry principle (a higher symmetry-higher stability relation) as a special case of the similarity principle. Some examples in chemical physics have been given. Spontaneous processes of all kinds of molecular interaction, phase separation and phase transition, including symmetry breaking and the densest molecular packing and crystallization, are all driven by information minimization or symmetry maximization. The evolution of the universe in general and evolution of life in particular can be quantitatively considered as a series of symmetry breaking processes. The two empirical rules - similarity rule and complementarity rule - have been given a theoretical foundation. All kinds of periodicity in space and time are symmetries and contribute to the stability. Symmetry is beautiful because it renders stability. However, symmetry is in principle ugly because it is associated with information loss.Comment: 29 pages, 14 figure

S-wave charmed mesons in lattice NRQCD

Heavy-light mesons can be studied using the 1/M expansion of NRQCD, provided the heavy quark mass is sufficiently large. Calculations of the S-wave charmed meson masses from a classically and tadpole-improved action are presented. A comparison of O(1/M), O(1/M^2) and O(1/M^3) results allows convergence of the expansion to be discussed. It is shown that the form of discretized heavy quark propagation must be chosen carefully.Comment: LATTICE98(heavyqk), 3 pages including 3 figure

Full-sky maps for gravitational lensing of the CMB

We use the large cosmological Millennium Simulation (MS) to construct the first all-sky maps of the lensing potential and the deflection angle, aiming at gravitational lensing of the CMB, with the goal of properly including small-scale non-linearities and non-Gaussianity. Exploiting the Born approximation, we implement a map-making procedure based on direct ray-tracing through the gravitational potential of the MS. We stack the simulation box in redshift shells up to $z\sim 11$, producing continuous all-sky maps with arcminute angular resolution. A randomization scheme avoids repetition of structures along the line of sight and structures larger than the MS box size are added to supply the missing contribution of large-scale (LS) structures to the lensing signal. The angular power spectra of the projected lensing potential and the deflection-angle modulus agree quite well with semi-analytic estimates on scales down to a few arcminutes, while we find a slight excess of power on small scales, which we interpret as being due to non-linear clustering in the MS. Our map-making procedure, combined with the LS adding technique, is ideally suited for studying lensing of CMB anisotropies, for analyzing cross-correlations with foreground structures, or other secondary CMB anisotropies such as the Rees-Sciama effect.Comment: LaTeX file, 10 pages, MNRAS in press, scales larger than the Millennium Simulation box size semi-analytically added, maps changed, references added, typos correcte

Measurements of Rate Coefficients for Reactions of OH with Ethanol and Propan-2-ol at Very Low Temperatures.

The low temperature kinetics of the reactions of OH with ethanol and propan-2-ol have been studied using a pulsed Laval nozzle apparatus coupled with pulsed laser photolysis-laser-induced fluorescence (PLP-LIF) spectroscopy. The rate coefficients for both reactions have been found to increase significantly as the temperature is lowered, by approximately a factor of 18 between 293 and 54 K for ethanol, and by ∼10 between 298 and 88 K for OH + propan-2-ol. The pressure dependence of the rate coefficients provides evidence for two reaction channels: a zero pressure bimolecular abstraction channel leading to products and collisional stabilization of a weakly bound OH-alcohol complex. The presence of the abstraction channel at low temperatures is rationalized by a quantum mechanical tunneling mechanism, most likely through the barrier to hydrogen abstraction from the OH moiety on the alcohol

On the convergence of quadrature formulas connected with multipoint Padé-type approximants

29 pages, no figures.-- MSC2000 codes: 41A55, 41A21.MR#: MR1408352 (97e:41066)Zbl#: Zbl 0856.41027^aLet $I(F)= \int^1_{- 1} F(x)\omega(x) dx$, where $\omega$ is a complex valued integrable function. We consider quadrature formulas for $I(F)$ which are exact with respect to rational functions with prescribed poles contained in \overline{\bbfC}\backslash [- 1, 1]. Their rate of convergence is studied.The research by the first three authors (P.G.-V., M.J.P., R.O.) was partially supported by the HCM project ROLLS, under Contract CHRX-CT93-0416. Research by the fourth author (G.L.L.) was carried out while on a visit at Universidad de La Laguna. This visit was made possible by a travel grant from CDE-IMU.Publicad