Flexural rigidity of hawkmoth antennae depends on the bending direction.

To probe its environment, the flying insect controllably flexes, twists, and maneuvers its antennae by coupling mechanical deformations with the sensory output. We question how the materials properties of insect antennae could influence their performance. A comparative study was conducted on four hawkmoth species: Manduca sexta, Ceratomia catalpae, Manduca quinquemaculata, and Xylophanes tersa. The morphology of the antennae of three hawkmoths that hover while feeding and one putatively non-nectar-feeding hawkmoth (Ceratomia catalpa) do not fundamentally differ, and all the antennae are comb-like (i.e., pectinate), markedly in males but weakly in females. Applying different weights to the free end of extracted cantilevered antennae, we discovered anisotropy in flexural rigidity when the antenna is forced to bend dorsally versus ventrally. The flexural rigidity of male antennae was less than that of females. Compared with the hawkmoths that hover while feeding, Ceratomia catalpae has almost two orders of magnitude lower flexural rigidity. Tensile tests showed that the stiffness of male and female antennae is almost the same. Therefore, the differences in flexural rigidity are explained by the distinct shapes of the antennal pectination. Like bristles in a comb, the pectinations provide extra rigidity to the antenna. We discuss the biological implications of these discoveries in relation to the flight habits of hawkmoths. Flexural anisotropy of antennae is expected in other groups of insects, but the targeted outcome may differ. Our work offers promising new applications of shaped fibers as mechanical sensors. STATEMENT OF SIGNIFICANCE: Insect antennae are blood-filled, segmented fibers with muscles in the two basal segments. The long terminal segment is muscle-free but can be flexed. Our comparative analysis of mechanical properties of hawkmoth antennae revealed a new feature: antenna resistance to bending depends on the bending direction. Our discovery replaces the conventional textbook scenario considering hawkmoth antennae as rigid rods. We showed that the pectinate antennae of hawkmoths behave as a comb in which the bristles resist bending when they come together. This anisotropy of flexural resistance offers a new mode of environmental sensing that has never been explored. The principles we found apply to other insects with non-axisymmetric antennae. Our work offers new applications for shaped fibers that could be designed to sense the flows.

The experience of diagnostic radiography students during the early stages of the COVID-19 pandemic - a cross-sectional study.

INTRODUCTION: The rationale for this study was to ascertain the impact of the COVID-19 pandemic on Undergraduate B.Sc (Hons) Diagnostic Radiography students at the University of Hertfordshire in the UK. This would provide an ideal opportunity for students to reflect on their experience and indicate if they required additional support from the University. METHODS: An online anonymous cross-sectional survey was deployed to all year groups (n = 283) during the first nationwide lockdown in May 2020, eliciting qualitative responses on questions about the effect of the pandemic; emotions experienced; support required and consideration of their choice of a career in the health sector. RESULTS: Two hundred and one students responded to the survey, with many having experienced the illness or loss of a loved one. Trying to balance family commitments and study was a concern to some students, as well as struggling with the financial burden of job losses or furlough. Many students commented that educational support was a requirement with the move to online teaching and assessment. The main focus of student responses was the emotions that they had experienced, many of which were negative. Anxiety and fear were commonly expressed feelings, along with sadness and feelings of isolation. A small number of students reported feeling grateful, happy and relieved. An overwhelming majority of respondents commented that they were proud to be healthcare students and they were resolute in wanting to continue the course and join the frontline of the NHS workforce. CONCLUSION: Some students have been deeply affected by their experiences of the pandemic, and University support mechanisms should be refined to better assist with their ongoing challenges.

Therapeutic hypothermia augments the restorative effects of PKC-ß and Nox2 inhibition on an in vitro model of human blood-brain barrier.

To investigate whether therapeutic hypothermia augments the restorative impact of protein kinase C-ß (PKC-ß) and Nox2 inhibition on an in vitro model of human blood-brain barrier (BBB). Cells cultured in normoglycaemic (5.5 mM) or hyperglycaemic (25 mM, 6 to 120 h) conditions were treated with therapeutic hypothermia (35 °C) in the absence or presence of a PKC-ß inhibitor (LY333531, 0.05 µM) or a Nox2 inhibitor (gp91ds-tat, 50 µM). BBB was established by co-culture of human brain microvascular endothelial cells (HBMECs) with astrocytes (HAs) and pericytes. BBB integrity and function were assessed via transendothelial electrical resistance (TEER) and paracellular flux of sodium fluorescein (NaF, 376 Da). Nox activity (lucigenin assay), superoxide anion production (cytochrome-C reduction assay), cellular proliferative capacity (wound scratch assay) and actin cytoskeletal formation (rhodamine-phalloidin staining) were assessed both in HBMECs and HAs using the specific methodologies indicated in brackets. Therapeutic hypothermia augmented the protective effects of PKC-ß or Nox2 inhibition on BBB integrity and function in experimental setting of hyperglycaemia, as evidenced by increases in TEER and concomitant decreases in paracellular flux of NaF. The combinatory approaches were more effective in repairing physical damage exerted on HBMEC and HA monolayers by wound scratch and in decreasing Nox activity and superoxide anion production compared to sole treatment regimen with either agent. Similarly, the combinatory approaches were more effective in suppressing actin stress fibre formation and maintaining normal cytoskeletal structure. Therapeutic hypothermia augments the cerebral barrier-restorative capacity of agents specifically targeting PKC-ß or Nox2 pathways.