Ocular exposure to occupational non-ionising radiation in professional pilots

Research evidence supports the link between long term exposure to ultraviolet (UV) and the blue light hazard with ocular damage including cataract and macular degeneration. Population studies to determine the prevalence of these conditions in pilots are inconclusive. It is known that UV and blue light intensities increase with altitude. The aim of this research was to investigate whether professional pilots are adequately protected from UV and short wavelength light during flight. Informed by the results of 22 semi-structured interviews, a questionnaire exploring the eye protection habits of professional pilots was developed and completed by 2,967 participants. The results showed a wide variation in pilot use of sunglasses, uncovered barriers preventing sunglass use and showed a high level of dissatisfaction regarding standard aircraft sun protection systems. In flight irradiance measurements were captured during 6 airline and 4 helicopter flights. No measurable UVB was found. UVA exposure was highly reliant on the transmission properties of the aircraft windshield. Further ground measurements on 15 aircraft showed the majority had windshields which transmit significant levels of UVA into the cockpit. This can cause the ocular dose for the unprotected eye to exceed international recommended exposure limits within ½ hour of flight. Older aircraft generally had superior UVA blocking windshields. Although calculated retinal exposure to blue light hazard during flight fell well within international recommended limits, the mean radiance was 4.1 times higher at altitude. The effect of this over a flying career remains uncertain. Filter transmittance measurements were taken from 34 pilot sunglasses and 20 new sunglasses typically used by pilots. All sunglasses filters measured offered sufficient protection from UVA in flight and ensured an attenuation of the blue light hazard to levels equivalent to those at ground level without protection. A series of practical recommendations are made to pilots, eye care health professionals, industry and the aviation regulator

Sunglass Filter Transmission and Its Operational Effect in Solar Protection for Civilian Pilots.

INTRODUCTION: The ocular effects of excess solar radiation exposure are well documented. Recent evidence suggests that ocular ultraviolet radiation (UVR) exposure to professional pilots may fall outside international guideline limits unless eye protection is used. Nonprescription sunglasses should be manufactured to meet either international or national standards. The mean increase in UVR and blue light hazards at altitude has been quantified and the aim of this research was to assess the effectiveness of typical pilot sunglasses in reducing UVR and blue light hazard exposure in flight. METHOD: A series of sunglass filter transmittance measurements were taken from personal sunglasses (N = 20) used by pilots together with a series of new sunglasses (N = 18). RESULTS: All nonprescription sunglasses measured conformed to international standards for UVR transmittance and offered sufficient UVR protection for pilots. There was no difference between right and left lenses or between new and used sunglasses. All sunglasses offered sufficient attenuation to counter the mean increase in blue light exposure that pilots experience at altitude, although used sunglasses with scratched lenses were marginally less effective. One pair of prescription sunglasses offered insufficient UVR attenuation for some flights, but would have met requirements of international and national standards for UV-A transmittance. This was likely due to insufficient UVR blocking properties of the lens material. CONCLUSIONS: Lenses manufactured to minimally comply with standards for UVR transmittance could result in excess UVR exposure to a pilot based on in-flight irradiance data; an additional requirement of less than 10% transmittance at 380 nm is recommended

Radio frequency measurements of tunnel couplings and singlet–triplet spin states in Si:P quantum dots

Spin states of the electrons and nuclei of phosphorus donors in silicon are strong candidates for quantum information processing applications given their excellent coherence times. Designing a scalable donor-based quantum computer will require both knowledge of the relationship between device geometry and electron tunnel couplings, and a spin readout strategy that uses minimal physical space in the device. Here we use radio frequency reflectometry to measure singlet–triplet states of a few-donor Si:P double quantum dot and demonstrate that the exchange energy can be tuned by at least two orders of magnitude, from 20 μeV to 8 meV. We measure dot–lead tunnel rates by analysis of the reflected signal and show that they change from 100 MHz to 22 GHz as the number of electrons on a quantum dot is increased from 1 to 4. These techniques present an approach for characterizing, operating and engineering scalable qubit devices based on donors in silicon

GIS and spatial data analysis: Converging perspectives

We take as our starting point the state of geographic information systems (GIS) and spatial data analysis 50 years ago when regional science emerged as a new field of enquiry. In the late 1950s and 1960s advances in computing technology were making possible forms of automated cartography that in due course would lead to th