The same but different: setal arrays of anoles and geckos indicate alternative approaches to achieving similar adhesive effectiveness.

The functional morphology of squamate fibrillar adhesive systems has been extensively investigated and has indirectly and directly influenced the design of synthetic counterparts. Not surprisingly, the structure and geometry of exemplar fibrils (setae) have been the subject of the bulk of the attention in such research, although variation in setal morphology along the length of subdigital adhesive pads has been implicated to be important in the effective functioning of these systems. Adhesive setal field configuration has been described for several geckos, but that of the convergent Anolis lizards, comprised of morphologically simpler fibrils, remains largely unexplored. Here, we examine setal morphology along the proximodistal axis of the digits of Anolis equestris and compare our findings to those for a model gecko, Gekko gecko. Consistent with previous work, we found that the setae of A. equestris are generally thinner, shorter, and present at higher densities than those of G. gecko and terminate in a single spatulate tip. Contrastingly, the setae of G. gecko are hierarchically branched in structure and carry hundreds of spatulate tips. Although the splitting of contacts into multiple smaller tips is predicted to increase the adhesive performance of a fiber compared to an unbranched one, we posited that the adhesive performance of G. gecko and A. equestris would be relatively similar when the configuration of the setal fields of each was accounted for. We found that, as in geckos, setal morphology of A. equestris follows a predictable pattern along the proximodistal axis of the pad, although there are several critical differences in the configuration of the setal fields of these two groups. Most notably, the pattern of variation in setal length of A. equestris is effectively opposite to that exhibited by G. gecko. This difference in clinal variation mirrors the difference in the direction in which the setal fields of anoles and geckos are peeled from the substrate, consistent with the hypothesis that biomechanical factors are the chief determinants of these patterns of variation. Future empirical work, however, is needed to validate this. Our findings set the stage for future comparative studies investigating the functional morphology of these convergent adhesive apparatuses. Such investigations will lead to an enhanced understanding of the interactions between form, function, and environment of fibril-based biological adhesive systems.

"You're on ten, where can you go from there?" Tufnel problems in repeated experiential judgments.

We describe a set of Tufnel problems that arise when repeated use of a fixed-point scale precipitates failures to assess a full range of subjective experiences. As empirical evidence, participants in Study 1 periodically reported their depth of mind wandering on either 5- or 7-point Likert scales during a sustained attention task. The proportion of participants providing maximum scale ratings increased quickly over time-on-task and did so more quickly for the 5-point than for the 7-point group. Participants in Study 2 completed the same task using a 10-point scale before indicating whether and where they could have used a scale extended to "11" during the task. Slightly more than 20% of participants reported needing a scale extension. This Need for 11 was associated with differences in both reports of mind wandering depth and task performance. We conclude that Tufnel problems warrant methodological consideration and reflect interesting constraints on human judgment.

Inherited cause of in utero digital malformations.

Amniotic band sequence (ABS) is common birth defect of incompletely understood origin. Here we describe a case of ABS in a child with paternally inherited Ehlers-Danlos syndrome, vascular type (vEDS). This is the third reported instance of ABS associated with paternally inherited vEDS in the medical literature. The two main theories of ABS formation are the extrinsic and intrinsic. The extrinsic theory states that placental tears form fibrous cords that wrap around the fetus; the intrinsic states that poor vascularisation in the fetus leads to necrosis of distal extremities. We believe this case supports extrinsic theory as it shows that as an amnion weakened by vEDS in fetal components is associated with ABS.

3-Tesla versus 1.5-Tesla magnetic resonance diffusion and perfusion imaging in hyperacute ischemic stroke.

BACKGROUND: Clinical 3-tesla magnetic resonance imaging systems are becoming widespread. No studies have examined differences between 1.5-tesla and 3-tesla imaging for the assessment of hyperacute ischemic stroke (<6 h from symptom onset). Our objective was to compare 1.5-tesla and 3-tesla diffusion and perfusion imaging for hyperacute stroke using optimized protocols. METHODS: Three patients or their surrogate provided informed consent. Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) was performed sequentially at 1.5 T and 3 T. DWI, apparent diffusion coefficient (ADC) maps and relative time-to-peak (TTP) maps were registered and assessed. DWI contrast-to-noise ratio (CNR) and ADC contrast were measured and compared. The infarct lesion volume (ILV) and thresholded ischemic volume (TIV) were estimated on the ADC and TTP maps, respectively, with the penumbral volume being defined as the difference between these volumes. RESULTS: Qualitatively, the 3-tesla TTP images exhibited greater feature detail. Quantitatively, the DWI CNR and ILV were similar at both field strengths, the ADC contrast was greater at 3 T and the TIV and penumbral volumes were much smaller at 3 T. CONCLUSIONS: Overall, the 3-tesla diffusion and perfusion images were at least as good and in some ways superior to the 1.5-tesla images for assessing hyperacute stroke. The TTP maps showed greater feature detail at 3 T. The ischemic and penumbra volumes were much greater at 1.5 T, indicating a potential difference in the diagnostic utility of the PWI-DWI mismatch between field strengths.