A comparison of learning with haptic and visual modalities.

The impact of haptic feedback on the perception of unknown objects (10 without texture, 10 with texture, and 2 complex shapes) was examined. Using a point probe (a PHANTOM), three treatment groups of students (visual, haptic, and visual plus haptic feedback) explored a set of virtual objects. The visual treatment group observed the objects through a small circular aperture. Accuracy of perception, exploration time, and description of objects were compared for the three treatment groups. Participants included 45 visually normal undergraduate students distributed across the three treatment groups and 4 blind students composing a second hapticonly group. Results showed that, within the normally sighted students, the haptic and haptic plus visual groups were slightly slower in their explorations than the visual group. The haptic plus visual group was more accurate in identifying objects than the visual or haptic-only groups. The terms used by the haptic treatment group to describe the objects differed from the visual and visual plus haptic groups, suggesting that these modalities are processed differently. There were no differences across the three groups for long-term memory of the objects. The haptic group was significantly more accurate in identifying the complex objects than the visual or visual plus haptic groups. The blind students using haptic feedback were not significantly different from the other haptic-only treatment group of normally-sighted participants for accuracy, exploration pathways, and exploration times. The haptic-only group of participants spent more time exploring the back half of the virtual objects than the visual or visual plus haptic participants. This finding supports previous research showing that the use of the PHANTOM with haptic feedback tends to support the development of 3-dimensional understandings of objects

Development and Characterization of Novel Empty Adenovirus Capsids and Their Impact on Cellular Gene Expression

Adenovirus (Ad) has been extensively studied as a eukaryotic viral vector. As these vectors have evolved from first-generation vectors to vectors that contain either very few or no viral genes (“gutless” Ad), significant reductions in the host innate immune response upon infection have been observed. Regardless of these vector improvements an unknown amount of toxicity has been associated with the virion structural proteins. Here we demonstrate the ability to generate high particle numbers (10(11) to 10(12)) of Ad empty virions based on a modification of Cre/lox gutless Ad vectors. Using a battery of analyses (electron microscopy, atomic force microscopy, confocal images, and competition assays) we characterized this reagent and determined that it (i) makes intact virion particles, (ii) competes for receptor binding with wild-type Ad, and (iii) enters the cell proficiently, demonstrating an ability to carry out essential steps of viral entry. To further study the biological impact of these Ad empty virions on infected cells, we carried out DNA microarray analysis. Compared to that for recombinant Ad, the number of mRNAs modulated upon infection was significantly reduced but the expression signatures were similar. This reagent provides a valuable tool for studies of Ad in that researchers can examine the effect of infection in the presence of the virion capsid alone

Data from: Mechanisms of Gill-Clogging by Hagfish Slime

Abstract of Proc. Roy. Soc. article: Hagfishes defend themselves from gill-breathing predators by producing large volumes of fibrous slime when attacked. The slime’s effectiveness comes from its ability to clog predators’ gills, but the mechanisms by which hagfish slime clogs are uncertain, especially given its remarkably dilute concentration of solids. We quantified the clogging performance of hagfish slime over a range of concentrations, measured the contributions of its mucous and thread components, and measured the effect of turbulent mixing on clogging. To assess the porous structure of hagfish slime, we used a custom device to measure its Darcy permeability. We show that hagfish slime clogs at extremely dilute concentrations like those found in native hagfish slime and displays clogging performance that is superior to three thickening agents. We report an extremely low Darcy permeability for hagfish slime, and an effective pore size of 10-300 nm. We also show that the mucous and thread components play distinct yet crucial roles, with mucus being responsible for effective clogging and low permeability and the threads imparting mechanical strength and retaining clogging function over time. Our results provide new insights into the mechanisms by which hagfish slime clogs gills and may inspire the development of ultra-soft materials with novel properties