Stratum corneum and epidermal layers change in terms of thickness and roughness with gender, age and anatomical site. Knowledge of the mechanical and tribological properties of skin associated with these structural changes are needed to aid in the design of exoskeletons, prostheses, orthotics, body mounted sensors used for kinematics measurements and in optimum use of wearable on-body devices. In this case study, optical coherence tomography (OCT) and digital image correlation (DIC) were combined to determine skin surface strain and sub-surface deformation behaviour of the volar forearm due to natural tissue stretching. The thickness of the epidermis together with geometry changes of the dermal-epidermal junction boundary were calculated during change in the arm angle, from flexion (90°) to full extension (180°). This posture change caused an increase in skin surface Lagrange strain, typically by 25% which induced considerable morphological changes in the upper skin layers evidenced by reduction of epidermal layer thickness (20%), flattening of the dermal-epidermal junction undulation (45-50% reduction of flatness being expressed as Ra and Rz roughness profile height change) and reduction of skin surface roughness Ra and Rz (40-50%). The newly developed method, DIC combined with OCT imaging, is a powerful, fast and non-invasive methodology to study structural skin changes in real time and the tissue response provoked by mechanical loading or stretching.

No abstract

Production of cool-season (C 3 ) herbage generally is low in summer and fall in the humid eastern USA. This study was conducted to determine the yields and pest problems of spring-sown turnip, Brassica rapa L.; swede, B. napus L.; rape, B. napus L.; interspecific crosses between chinese cabbage, B. campestris sensulato L., and turnip or rape; or kale, B. oleracea L., that were stockpiled. The crops were no-till seeded (turnip and swede at 1.4 kg ha-•, rape, the hybrids, and kale at 4.2 kg ha -•) into mature alfalfa (Medicago sativa L.)-grass stands. Prior to seeding, the sod was treated with isopropylamine salt of N-(phosphonomethyl) glycine at 1.1 kg a.i. ha-•. The study was made in central Pennsylvania on Hagerstown silt loam (fine, mixed, mesic Typic Hapludalfs) soil in 1979 and 1980 and on Hublersburg silt loam (clayey, illitic, mesic Typic Hapludults) soil in 1981. Dry matter yield determinations were made sequentially at 30-day intervals from 60 to ISO days post-seeding. Fertilizer (P and K) was applied according to soil test results and 80 kg N ha-1 was applied at seeding and 70 kg N ha-• between the 60-and 90-day sampling dates. Three-year mean dry matter yields for 13 of 19 cultivars exceeded 7.0 Mg ha-• 90 days post-seeding. Yields plateaued from 80 to 160 days depending on plant species, cultivar, and year. Cultivar (across species) X sampling date, turnip cultivar X year, and swede, rape, and kale sampling date X year interactions were significant for yield. Incidence of plant diseases was positively related to slowing of growth at physiological maturity. Some New Zealand turnip and rape cultivars were more resistant to flea beetle [Phyllotreta cruciferae Goeze and P. striolata (Fab.)l than

No abstract

Measurement of sub-clinical atopic dermatitis (AD) is important for determining how long therapies should be continued after clinical clearance of visible AD lesions. An important biomarker of sub-clinical AD is epidermal hypertrophy, the structural measures of which often make optical coherence tomography (OCT) challenging due to the lack of a clearly delineated dermal-epidermal junction in AD patients. Alternatively, angiographic OCT measurements of vascular depth and morphology may represent a robust biomarker for quantifying the severity of clinical and sub-clinical AD. To investigate this, angiographic data sets were acquired from 32 patients with a range of AD severities. Deeper vascular layers within skin were found to correlate with increasing clinical severity. Furthermore, for AD patients exhibiting no clinical symptoms, the superficial plexus depth was found to be significantly deeper than healthy patients at both the elbow (p = 0.04) and knee (p<0.001), suggesting that sub-clinical changes in severity can be detected. Furthermore, the morphology of vessels appeared altered in patients with severe AD, with significantly different vessel diameter, length, density and fractal dimension. These metrics provide valuable insight into the sub-clinical severity of the condition, allowing the effects of treatments to be monitored past the point of clinical remission.