Sticking under wet conditions: the remarkable attachment abilities of the torrent frog, staurois guttatus

Tree frogs climb smooth surfaces utilising capillary forces arising from an air-fluid interface around their toe pads, whereas torrent frogs are able to climb in wet environments near waterfalls where the integrity of the meniscus is at risk. This study compares the adhesive capabilities of a torrent frog to a tree frog, investigating possible adaptations for adhesion under wet conditions. We challenged both frog species to cling to a platform which could be tilted from the horizontal to an upside-down orientation, testing the frogs on different levels of roughness and water flow. On dry, smooth surfaces, both frog species stayed attached to overhanging slopes equally well. In contrast, under both low and high flow rate conditions, the torrent frogs performed significantly better, even adhering under conditions where their toe pads were submerged in water, abolishing the meniscus that underlies capillarity. Using a transparent platform where areas of contact are illuminated, we measured the contact area of frogs during platform rotation under dry conditions. Both frog species not only used the contact area of their pads to adhere, but also large parts of their belly and thigh skin. In the tree frogs, the belly and thighs often detached on steeper slopes, whereas the torrent frogs increased the use of these areas as the slope angle increased. Probing small areas of the different skin parts with a force transducer revealed that forces declined significantly in wet conditions, with only minor differences between the frog species. The superior abilities of the torrent frogs were thus due to the large contact area they used on steep, overhanging surfaces. SEM images revealed slightly elongated cells in the periphery of the toe pads in the torrent frogs, with straightened channels in between them which could facilitate drainage of excess fluid underneath the pad

Reaching 52bu/ac of Canola by 2025

Non-Peer ReviewedThe canola industry goal set by the Canola Council of Canada is to reach an average production level of 52 bu/ac by the year 2025. The pillars to reach this target include Genetic Improvements, and improved management of four agronomic areas; Plant Establishment, Fertility Management, Integrated Pest Management, and Harvest Management. Yields have increased since the establishment of this target, but still need to improve to reach the desired target. Several management practice improvements have been identified to help support achieving 52 bu/ac of canola by 2025

Elastic modulus of tree frog adhesive toe pads

Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5–15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4–25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs

Autumn Graves interview

Oral history interview documenting the history of women in Chattanooga conducted as part of the work of the City of Chattanooga's Mayor's Council for Women History Committee, which was established in 2015 to create positive change to advance the status of women and their families in the city and throughout the region

Mindfulness and Emotion Regulation among Nursing Students: Investigating the Mediation Effect of Working Memory Capacity

This study examined the relationship between mindfulness and emotion regulation in nursing students as well as the potential mediator role of working memory capacity in this relationship. The Mindful Attention Awareness Scale (MAAS), Emotion Regulation Questionnaire (ERQ), and an Automated Operation Span Task (AOSPAN) were administered to 80 undergraduate pre-licensure baccalaureate nursing students. Pearson correlation, structural equation path modeling, and one-way ANOVA tests were conducted. MAAS scores were significantly correlated with ERQ-Reappraisal scores (r = 0.19, p = 0.045) and AOSPAN scores (r = 0.30, p = 0.004). A structural equation path model indicated that there was a direct effect of dispositional mindfulness on emotion regulation (γ11 = 0.29, p = 0.034) and working memory capacity (γ21 = 4.98, p = 0.004). However, working memory capacity did not directly mediate the effect of mindfulness on emotion regulation (b weight = −0.03, p = 0.236). Also, MAAS scores were significantly different (p \u3c 0.05) between the student cohort levels, with the first semester students having the highest MAAS scores and the fourth semester students have the lowest MAAS scores. These findings suggest that mindfulness may influence prospective nursing professionals’ working memory capacity and ability to regulate emotions. However, working memory capacity did not explain how mindfulness influenced the use of reappraisal as an emotion regulation strategy. Nurse educators should consider other potential mechanisms of how mindfulness influences emotion regulation in nursing students. Furthermore, educators should consider that potential differences in mindfulness exist between nursing students when they implement mindfulness-based interventions

Self-cleaning in tree frog toe pads; a mechanism for recovering from contamination without the need for grooming

Tree frogs use adhesive toe pads for climbing on a variety of surfaces. They rely on wet adhesion, which is aided by the secretion of mucus. In nature, the pads will undoubtedly get contaminated regularly through usage, but appear to maintain their stickiness over time. Here, we show in two experiments that the toe pads of White's tree frogs (Litoria caerulea) quickly recover from contamination through a self-cleaning mechanism. We compared adhesive forces prior to and after contamination of (1) the whole animal on a rotatable platform and (2) individual toe pads in restrained frogs mimicking individual steps using a motorised stage. In both cases, the adhesive forces recovered after a few steps but this took significantly longer in single toe pad experiments from restrained frogs, showing that use of the pads increases recovery. We propose that both shear movements and a ‘flushing’ effect of the secreted mucus play an important role in shedding particles/contaminants

Variation in time and magnitude of immune response and viremia in experimental challenges with Porcine circovirus 2b

Background: Porcine circovirus 2 is the primary agent responsible for inducing a group of associated diseases known as Porcine Circovirus Associated Diseases (PCVAD), which can have detrimental effects on production efficiency as well as causing significant mortality. The objective of this study was to evaluate variation in viral replication, immune response and growth across pigs (n = 974) from different crossbred lines. The approach used in this study was experimental infection with a PCV2b strain of pigs at an average of 43 days of age. Results: The sequence of the PCV2b isolate used in the challenge was similar with a cluster of PCV2b isolates known to induce PCVAD and increased mortality rates. The swine leukocyte antigen class II (SLAII) profile of the population was diverse, with nine DQB1 haplotypes being present. Individual viremia and antibody profiles during challenge demonstrate variation in magnitude and time of viral surge and immune response. The correlations between PCV2 specific antibodies and average daily gain (ADG) were relatively low and varied between - 0.14 to 0.08 for IgM and −0.02 and 0.11 for IgG. In contrast, PCV2 viremia was an important driver of ADG decline following infection; a moderate negative correlation was observed between viral load and overall ADG (r = − 0.35, P \u3c 0.001). The pigs with the lowest 10% level of viral load maintained a steady increase in weekly ADG (P \u3c 0.0001) compared to the pigs that had the 10% greatest viral load (P \u3c 0.55). In addition, the highly viremic group expressed higher IgM and IgG starting with d 14 and d 21 respectively, and higher tumor necrosis factor – alpha (TNF-α) at d 21 (P \u3c 0.005), compared to low viremic group. Conclusions: Molecular sources of the observed differences in viremia and immune response could provide a better understanding of the host factors that influence the development of PCVAD and lead to improved knowledge of swine immunity