Vitamin D production in human skin occurs only when incident UV radiation exceeds a certain threshold. From simulations of UV irradiances worldwide and throughout the year, we have studied the dependency of the extent and duration of cutaneous vitamin D production in terms of latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude. For clear atmospheric conditions, no c...

[1] We investigate streamer formation in the troposphere, in electric fields above the breakdown threshold. With fully three-dimensional particle simulations, we study the combined effect of natural background ionization and of photo-ionization on the discharge morphology. In previous investigations based on deterministic fluid models without background ionization, so-called double-headed strea...

The use of mercuric chloride as an histological fixative was associated with high environmental atmospheric concentrations of mercury vapour (up to 0-5 nmol/l) as well as mercury compounds (total Hg to 1-0 nmol/l). Technicians exposed to this environment showed increased urinary mercury (median value 265 nmol/24h) and protein outputs (median value 117 mg protein/24h). Routine control measures, ...

In this paper, the efficiency of the gyroscopic mounting method is studied for a highly dynamic GNSS receiver's reference oscillator for reducing signal loss. Analyses are performed separately in two phases, atmospheric and upper atmospheric flights. Results show that the proposed mounting reduces signal loss, especially in parts of the trajectory where its probability is the highest. This redu...

The distinct contrast between the reflectance of solar radiation in Advanced Very High Resolution Radiometer (AVHRR) channel 3 (3.75 mm) by clouds and by bright surfaces provides an effective means of cloud discrimination over snow/ice surfaces. A threshold function for the top-of-atmosphere (TOA) albedo in channel 3 (r3) is derived and used to develop an improved method for cloud discriminatio...

Industrial equipments and systems can suffer structural damage when hit by earthquakes, so that accidental scenarios as fire, explosion and dispersion of toxic substances can take place. As a result, overall damage to people, environment and properties increases. The present paper deals with seismic risk analysis of industrial facilities where atmospheric storage tanks (anchored or unanchored t...

Among the issues raised by the globally ice-covered Earth, or a so-called ‘hard’ snowball–Earth scenario, one of the most important is to establish the CO2 threshold required for the deglaciation. This problem has been addressed using the Energy-Balance Model (or EBM), which showed that for Neoproterozoic insolation, 0.29 bar of CO2 would be needed to trigger deglaciation. New results, obtained...

In free-space optical links using intensity modulation and direct detection, atmospheric turbulence can cause signal fading. Pilot-symbol (PS) assisted modulation (PSAM) can help to mitigate this fading, improving system performance. We periodically insert an On-state PS in front of M-1 information bits and form a M-bit frame. We derive the PS assisted maximum-likelihood (PSA-ML) decision rule ...

Vitamin D production in human skin occurs only when incident UV radiation exceeds a certain threshold. From simulations of UV irradiances worldwide and throughout the year, we have studied the dependency of the extent and duration of cutaneous vitamin D production in terms of latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude. For clear atmospheric conditions, no c...

We have proposed to set up an experiment to detect celestial γ-rays of energy ≥ 20 GeV using the atmospheric Čerenkov Technique at Hanle, a high altitude location in the Himalayas. The limited lateral spread of the Čerenkov light pool, near 90% atmospheric transmission of Čerenkov light and low sky brightness makes this high altitude site an ideal place to set up a ground-based γray observatory...