Evaluating the usability of a mobile guide: the influence of location, participants and resources

When designing a usability evaluation, choices must be made regarding methods and techniques for data collection and analysis. Mobile guides raise new concerns and challenges to established usability evaluation approaches. Not only are they typically closely related to objects and activities in the user's immediate surroundings, they are often used while the user is ambulating. This paper presents results from an extensive, multi-method evaluation of a mobile guide designed to support the use of public transport in Melbourne, Australia. In evaluating the guide, we applied four different techniques; field-evaluation, laboratory evaluation, heuristic walkthrough and rapid reflection. This paper describes these four approaches and their respective outcomes, and discusses their relative strengths and weaknesses for evaluating the usability of mobile guides.     

Vicarious experience in retail e-commerce: An inductive taxonomy of product evaluation support features

In general, direct experience (touch, taste, use, and so on) of physical products is impossible in an online environment. Knowledge of the experience attributes of these goods must therefore be obtained via an intermediary (vicariously). Unfortunately, little has been published about how to design online retail systems that help customers evaluate physical products. This paper addresses that gap by (1) surveying a wide range of sites, and (2) evaluating the features found using a grounded, rigorous evaluation method to induce a taxonomy of vicarious experience. The taxonomy is then used as the basis for some theory-based conjectures about the types of designs most suitable for different types of product. In particular, we propose that the type of information form and community used should differ for value-expressive and utilitarian goods, and for high and low-involvement goods.     

Determining the incremental worth of members of an aggregate set through difference-based induction

Calculating the incremental worth or weight of individual components of an aggregate set when only the whole set's total worth or weight is known is a problem common to several domains. Here we describe an algorithm that induces such incremental worth from a database of similar (not identical) aggregate sets. The algorithm focuses on finding aggregate sets in the database exhibiting minimal differences in corresponding components (attributes and values). This procedure isolates dissimilarities between nearly similar aggregate sets so any difference in worth between sets is attributed to them. The algorithm builds a classification tree similar to those of ID3 and C4.5 distributes all aggregate sets in the database according to their attributes and values; and groups together those with the same attributes and values. Each leaf of the classification tree then contains a group of aggregate sets identical to each other insofar as their attribues and values. Groups' members belonging to two sibling leaves (having the same immediate parent) differ from each other in the value of exactly one attribute. Thus, any difference in the worth of sets in those groups can be attributed to that difference. The worth of the aggregate sets in these groups can be averaged when data are noisy. This algorithm works well when applied to real-estate appraisal domain. ©1999 John Wiley & Sons, Inc.     

Permeability characterization. Part 2: Flow behavior in multiple-layer preforms

Within the resin transfer molding (RTM) process, flow is generally characterized by the progression of a distinct, nonuniform flow front into the preform as a function of time. The flow front progression introduces unsaturated characteristics into RTM flow fields. As a result, the definition of an effective in-plane permeability (K_eff) is used to determine the permeability of actual preforms as they fill with fluid. This K_eff expression expands upon the original definition of Darcy's law by generalizing its applicability to unsaturated creeping flows. Results of experimentally obtained K_eff for flow in single-layer preforms have been detailed for two common RTM materials, a random mat and a 3-D weave, in Part 1. In this paper (Part 2), we characterize the unsaturated and saturated permeabilities of multiple-layer preforms constructed from the random mat and 3-D weave materials characterized in Part 1. This work identifies the apparent permeability characteristics of a specific unsaturated multiple-layer flow that demonstrates behavior inherent to this important class of heterogeneous flows. Also, parallels are drawn between the unsaturated permeability behavior of complex 3-D weave materials and multiple-layer preforms.     

Penetration and distribution of α-tocopherol, α- or γ-tocotrienols applied individually onto murine skin

To evaluate skin penetration of various vitamin E homologs, a 5% solution of either α-tocopherol, α-tocotrienol, or γ-tocotrienol in polyethylene glycol was topically applied to SKH-1 hairless mice. After 0.5, 1, 2, or 4 h (n=four per time point and four per vitamin E homolog), the skin was washed, the animals killed, the skin rapidlly removed, frozen on dry ice, and a biopsy taken and sectioned: stratum corneum (two uppermost, 5-μm sections—SC1 and SC2), epidermis (next two 10μm sections—E1 and E2), papillary dermis (next 100μ, PD), dermis (next 400 μm, D), and subcutaneous fat (next 100 μm, SF). SC1 contained the highest vitamin E concentrations per μ thickness. To compare the distribution of the various vitamin E forms into the skin layers, the percentage of each form was expressed per its respective total. Most surprising was that the largest fraction of skin vitamin E following topical application was found in the deeper subcutaneous layers—the lowest layers, PD (40±15%) and D (36±15%), contained the major portion of the applied vitamin E forms. Although PD only represents about 16% of the total skin thickness, it contains sebaceous glands—lipid secretory organs, and, thus, may account for the vitamin E affinity for this layer. Hence, applied vitamin E penetrates rapidly through the skin, but the highest concentrations are found in the uppermost 5 microns.     

Injection molding: The effect of fill time on properties

The effect of fill time on the mechanical properties, surface appearance, and part dimensions of several polymers was determined. Two crystalline materials, polypropylene and nylon 6,6, and an amorphous material, acrylonitrile-butadiene-styrene (ABS), were used. In addition, the effect of the presence of glass fibers was examined using glass fiber reinforced nylon 6,6. The fill time was varied from 0.8 to 20 sec which included both the viscous flow controlled region (short fill times) where laboratory samples are ordinarily molded and the heat transfer controlled region (long fill times) where production parts arc commonly molded. No large variations in tensile properties were observed for polypropylene or nylon, but a 10 percent increase in peak tensile stress and strain for ABS did indicate that molecular orientation increased with increasing fill time. However, significant differences did occur in the properties of glass reinforced nylon. Peak tensile stress increased 15 percent and flexural strength decreased 10 percent as the fill time was increased. Although no change in the flexural modulus was observed, the scatter in the modulus decreased with increasing fill time. These property variations can be attributed to differences in the glass fiber orientation of the skin and core regions of the part. The measurement of molded tensile bar dimensions indicated there was little effect of fill time on the shrinkage of the various polymers except for shrinkage in the length direction for polypropylene. The shrinkage increased from 13 to 15.4 mm/m over the fill time range, a great enough difference to affect the fit of large parts. The most dramatic change with fill time was the surface appearance of the glass reinforced nylon. The surface of samples molded at short fill times had a dark uniform color and smooth appearance while samples molded at long fill times had a lighter color and a porous surface. This surface porosity is due to crystallization prior to complete pressurization of the mold. Therefore, in addition to affecting surface appearance, other surface related properties such as aging and the ability to plate plastic parts could also be affected.     

Multiple cool flames in static, unstirred reactors under reduced-gravity and terrestrial conditions

Multiple cool flames have been observed experimentally in a static, unstirred reactor at reduced gravity in an equimolar n-butane-oxygen premixture diluted with helium. These are the first observations of sustained cool flame oscillations in a static reactor when transport is governed by diffusive fluxes of heat and species. To date, only single cool flames have been reported at reduced gravity, while oscillatory cool flames have long been observed in static reactors at terrestrial conditions. The results suggest that enhanced conduction heat transfer can provide the required heat loss to sustain cool flame oscillations.     

Hydroliquefaction of Wyodak coal using bottoms recycle

Wyodak coal has been liquefied using recycle solvents consisting of blends of Wyodak coal-derived distillates and SRC or SRC oils, asphaltenes and oils plus asphaltenes. Whilst the quality of the distillate portion of the bottoms recycle is maintained by hydrogenation and distillation in the Exxon Donor Solvent (EDS) process, no reported efforts have been made to hydrogenate the nondistillable portion of the EDS bottoms recycle solvent nor the bottoms recycle solvent in the SRC-II process. As hydrogenation of the distillate portion of the recycle solvent in the EDS process increased Wyodak coal distillate yields, this study was initiated to determine whether hydrogenation of the nondistillable portions of Wyodak coal-derived bottoms recycle solvent would show similar beneficial effects. Results suggest that distillable liquid yields in the range of 55–60 wt% of dry Wyodak coal can be obtained using mildly hydrogenated SRC or SRC oils plus asphaltenes as a bottoms recycle solvent component. This result can be compared to distillable liquid yields of 40 wt% of dry, Wyodak coal obtained from the EDS process using bottoms recycle. Further, the unhydrogenated, SRC-derived oil and asphaltene portions of the recycle solvent also appear to be effective solvent components. However, the most effective solvents were obtained using hydrogenated SRC or SRC-derived oils plus asphaltenes.     

Regulation of the metabolism of linoleic acid to arachidonic acid in rat hepatocytes

When 5×10⁶ hepatocytes were incubated for 40 min with from 0.15 to 0.60 mM [1-¹⁴C]linoleic acid, [1-¹⁴C]6,9,12-octadecatrienoic acid, or [1-¹⁴C]8,11,14-eicosatrienoic acid, there was a concentration-dependent acylation of radioactive metabolites into both triglycerides and phospholipids. When the concentration of either [1-¹⁴C]linoleic acid or [1-¹⁴C]8,11,14-eicosatrienoic acid exceeded 0.3 mM, there was no further increase in the metabolism of either fatty acid to other (n−6) metabolites. When the concentration of [1-¹⁴C]6,9,12-octadecatrienoic acid exceeded 0.15 mM, there was an apparent substrate-induced inhibition in its metabolism to 8,11,14-eicosatrienoic acid. With all three substrates (0.3 mM), there was time-dependent metabolism to other (n−6) acids. Cells then were incubated simultaneously with 0.3 mM [1-¹⁴C]linoleic acid along with 0.15 to 0.45 mM 6,9,12-octadecatrienoic acid or 8,11,14-eicosatrienoic acid. These exogenous nonradioactive (n−6) acids suppressed but did not abolish the conversion of [1-¹⁴C]linoleate to radioactive arachidonate. These findings suggest that some linoleate is converted to arachidonate without intracellular mixing of 6,8,12-octadecatrienoic or 8,11,14-eicosatrienoic acids. This hypothesis is supported by the finding that exogenous linoleate did not markedly affect the metabolism of [1-¹⁴C]6,9,12-octadecatrienoic or [1-¹⁴C]8,11,14-eicosatrienoic acid by microsomal chain elongating or desaturating enzymes.     

Hydrocarbons from males,females, and larvae of pecan weevil:Curculio caryae (Horn)

As part of a program to identify as many as possible of the components of the pecan weevil,Curculio caryae (Horn), the hydrocarbons from males, females, and larvae were isolated by solvent extraction and column chromatography and subjected to gas liquid chromatographymass spectrometry analysis. n-Alkanes from C₁₄−C₃₂ in the larvae and unsaturated and branched chain hydrocarbons from C₂₀−C₃₂ in males and females were found. There are no significant differences between the hydrocarbons of the male and female pecan weevils.