High variability in anatomic patterns of cutaneous photodamage: a population-based study.

BACKGROUND: Skin cancer is strongly associated with photodamaged skin, but body sites are often referred to as 'exposed' or 'unexposed' to sun without recognizing extent of site-specific variation. OBJECTIVES: To assess whole-body patterns of photodamage in an Australian population. METHODS: A random sample of adult residents of Queensland underwent imaging across 10 body sites. Photodamage was graded from images using an ordinal photonumeric scale. We used cluster analysis to identify whole-body photodamage patterns and prevalence proportion ratios (PPRs) to assess associated factors. RESULTS: Of 190 adults (median age 52; 58% males), 58% showed severe or moderate-to-severe photodamage on most body sites. A higher proportion of woman had severe photodamage on the arms (upper: P = 0.002, lower: P = 0.034). A higher proportion of men had moderate or severe photodamage on the lower back (P = 0.004). We identified four photodamage patterns: 'severe general' (n = 24, 13%), 'moderate-severe general' (n = 86, 45%), 'moderate-severe v-neck' (n = 40, 21%) and 'mild-moderate upper body' (n = 12, 6%). All participants with 'severe-general' photodamage were >50 years and more likely to have past skin cancer (PPR: 2.54, 95% CI: 1.44-4.49) than those with 'moderate-severe v-neck' photodamage. Those with 'moderate-severe general' photodamage showed similar associations and were more likely female (PPR: 1.33, 95% CI: 1.04-1.69). Past or current smoking was associated with having higher levels of photodamage, with no smokers in those with 'mild-moderate upper body' photodamage. CONCLUSIONS: Moderate-to-severe photodamage across much of the body is common in Queensland adults and associated with age, sex, past skin cancer and smoking. Assuming a universal pattern of site-specific sun exposure could lead to spurious correlations, while accurate and objective assessment of site-specific photodamage can add to understanding of the development of sun-associated skin cancers, in particular site-specific skin carcinogenesis. Additionally, degree of site-specific photodamage has the potential to assist skin cancer screening.

Probing Atmospheric Electric Fields in Thunderstorms through Radio Emission from Cosmic-Ray-Induced Air Showers.

We present measurements of radio emission from cosmic ray air showers that took place during thunderstorms. The intensity and polarization patterns of these air showers are radically different from those measured during fair-weather conditions. With the use of a simple two-layer model for the atmospheric electric field, these patterns can be well reproduced by state-of-the-art simulation codes. This in turn provides a novel way to study atmospheric electric fields.

Determining Electric Fields in Thunderclouds With the Radiotelescope LOFAR.

An analysis is presented of electric fields in thunderclouds using a recently proposed method based on measuring radio emission from extensive air shower events during thunderstorm conditions. This method can be regarded as a tomography of thunderclouds using cosmic rays as probes. The data cover the period from December 2011 till August 2014. We have developed an improved fitting procedure to be able to analyze the data. Our measurements show evidence for the main negative-charge layer near the -10° isotherm. This we have seen for a winter as well as for a summer cloud where multiple events pass through the same cloud and also the vertical component of the electric field could be reconstructed. On the day of measurement of some cosmic-ray events showing evidence for strong fields, no lightning activity was detected within 100 km distance. For the winter events, the top heights were between 5 and 6 km, while in the summer, typical top heights of 9 km were seen. Large horizontal components in excess of 70 kV/m of the electric fields are observed in the middle and top layers.

LOFAR Lightning Imaging: Mapping Lightning With Nanosecond Precision.

Lightning mapping technology has proven instrumental in understanding lightning. In this work we present a pipeline that can use lightning observed by the LOw-Frequency ARray (LOFAR) radio telescope to construct a 3-D map of the flash. We show that LOFAR has unparalleled precision, on the order of meters, even for lightning flashes that are over 20 km outside the area enclosed by LOFAR antennas (∼3,200 km2), and can potentially locate over 10,000 sources per lightning flash. We also show that LOFAR is the first lightning mapping system that is sensitive to the spatial structure of the electrical current during individual lightning leader steps.