Minimum Exposure Limits and Measured Relationships Between the Vitamin D,Erythema and International Commission on Non‐Ionizing Radiation Protection Solar Ultraviolet

The International Commission on Non‐Ionizing Radiation Protection (ICNIRP) has established guidelines for exposure to ultraviolet radiation in outdoor occupational settings. Spectrally weighted ICNIRP ultraviolet exposures received by the skin or eye in an 8 h period are limited to 30 J m^?2. In this study, the time required to reach the ICNIRP exposure limit was measured daily in 10 min intervals upon a horizontal plane at a subtropical Australian latitude over a full year and compared with the effective Vitamin D dose received to one‐quarter of the available skin surface area for all six Fitzpatrick skin types. The comparison of measured solar ultraviolet exposures for the full range of sky conditions in the 2009 measurement period, including a major September continental dust event, show a clear relationship between the weighted ICNIRP and the effective vitamin D dose. Our results show that the horizontal plane ICNIRP ultraviolet exposure may be used under these conditions to provide minimum guidelines for the healthy moderation of vitamin D, scalable to each of the six Fitzpatrick skin types.     

Evaluation of a high exposure solar UV dosimeter for underwater use

Solar ultraviolet radiation (UV) is known to have a significant effect upon the marine ecosystem. This has been documented by many previous studies using a variety of measurement methods in aquatic environments such as oceans, streams and lakes. Evidence gathered from these investigations has shown that UVB radiation (280-320 nm) can negatively affect numerous aquatic life forms, while UVA radiation (320-400 nm) can both damage and possibly even repair certain types of underwater life. Chemical dosimeters such as polysulphone have been tested to record underwater UV exposures and in turn quantify the relationship between water column depth and dissolved organic carbon levels to the distribution of biologically damaging UV underwater. However, these studies have only been able to intercept UV exposures over relatively short time intervals. This paper reports on the evaluation of a high exposure UV dosimeter for underwater use. The UV dosimeter was fabricated from poly 2,6-dimethyl-1,4-phenylene oxide (PPO) film. This paper presents the dose response, cosine response, exposure additivity and watermarking effect relating to the PPO dosimeter as measured in a controlled underwater environment and will also detail the overnight dark reaction and UVA and visible radiation response of the PPO dosimeter, which can be used for error correction to improve the reliability of the UV data measured by the PPO dosimeters. These results show that this dosimeter has the potential for long-term underwater UV exposure measurements.     

Dosimetric and spectroradiometric investigations of glass filtered solar UV

The aims of this paper were to investigate how glass-filtered UV irradiances vary with glass thickness, lamination of the glass and the effect of solar zenith angle (SZA), and to measure the glass-filtered UV exposures to different receiving planes with a newly developed UVA dosimeter. Spectroradiometric and dosimetric techniques were employed in the experimental approach. The percentage of the glass-filtered solar UV compared to the unfiltered UV ranged from 59% to 70% and was influenced to a small extent by the glass thickness and the SZA. The laminated glass transmitted 11 to 12% and the windscreen glass transmitted 2.5-2.6%. The influence of the SZA was less for the thicker glass than it was for the thinner glass. The change in transmission was less than 14% for the SZA between 48 degrees and 71 degrees. There was negligible influence due to the SZA on the glass-transmitted UV of the laminated and windscreen glass. The influence of the glass thickness in the range of 2-6 mm on the percentage transmission was less than 16%. The influences of the glass thickness and the SZA on the glass-transmitted UV have been incorporated in the use of a UVA dosimeter for the glass-transmitted UV exposures. The UVA dosimeter was employed in the field to measure the glass-filtered UV exposures to different receiving planes. The UVA dosimeter reported has the potential for personal solar UVA exposure measurements.     

A transversely isotropic composite with a statistical distribution of spheroidal inclusions: a geometrical approach to overall properties

In the literature, the determination of global elastic properties of composites with ellipsoidal inclusions is based on the averaged stress, strain and elastic-energy fields (e.g. Compos. Sci. Technol. 27 (1986) 111). These are related to the local fields of the inclusion, the matrix, and the inclusion-matrix interface. In this study, we propose a method to obtain the global elastic properties of any transversely isotropic composite directly from the elastic properties of the matrix and the inclusions. Thus, it is not necessary to refer to the stress and strain applied globally or generated locally. The inclusions can have any transversely isotropic probability distribution of orientation. The problem is entirely geometrized and is treated in terms of averages of Walpole's (Adv. Appl. Mech. 21 (1981) 169) components of the fourth-order tensors describing the problem. We give a general numerical solution for any transversely isotropic statistical distribution of orientation, and also provide a validation of our method by applying it to some known cases and by retrieving the known exact solutions from the literature.     

Usage of the Polyphenylene Oxide Dosimeter to Measure Annual Solar Erythemal Exposures

Poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) film is a useful dosimetric tool for measuring solar UV in underwater and terrestrial environments. However, little is known about how the response of PPO changes with fluctuations in atmospheric ozone and also to seasonal variations. To resolve this issue this article presents a series of long-term in-air solar erythemal response measurements made over a year from 2007 to 2008 with PPO. This data showed that the PPO dose response varies with modulations of the solar spectrum resulting from changes in season and atmospheric ozone. From this, it was recommended that PPO only be calibrated in the season in which it is to be used at the same time as measurements were being made in the field. Extended solar UV measurements made by PPO with a neutral density filter (NDF) based on polyethylene are also detailed. These measurements showed that the lifetime of PPO could be extended by 5 days before saturation. As the dynamic range for PPO is known to be 5 days during summer at a sub-tropical location, the advantage of using the NDF is that half the number of dosimeters is needed to be fabricated and measured before and after exposure.     

A multiscale Darcy–Brinkman model for fluid flow in fractured porous media

The aim of this work is to present a reduced mathematical model for describing fluid flow in porous media featuring open channels or fractures. The Darcy’s law is assumed in the porous domain while the Stokes–Brinkman equations are considered in the fractures. We address the case of fractures whose thickness is very small compared to the characteristic diameter of the computational domain, and describe the fracture as if it were an interface between porous regions. We derive the corresponding interface model governing the fluid flow in the fracture and in the porous media, and establish the well-posedness of the coupled problem. Further, we introduce a finite element scheme for the approximation of the coupled problem, and discuss solution strategies. We conclude by showing the numerical results related to several test cases and compare the accuracy of the reduced model compared with the non-reduced one.     

A Hierarchy of Chains Embeddable into the Lexicographic Power \boldsymbol{({\mathbb{R}}^\omega,\prec_{\rm lex})}

A hierarchy of chains is a transfinite sequence of linear orderings such that each chain in the sequence order-embeds into all chains following it but not in those preceding it. We construct a c ^?+?-long hierarchy of chains that order-embed into the lexicographic power $({\mathbb{R}}^\omega,\prec_{\rm lex})$ . Each linear ordering L in this hierarchy is such that there exists a tree representation of L, which is an ?-branching tree with no infinite branches. The existence of such a hierarchy sheds some light on the hidden complexity of $({\mathbb{R}}^\omega,\prec_{\rm lex})$ .     

Sulle algebre per cui vale il teorema degli zeri di Hilbert generalizzato

Riassunto In questo lavoro studiamo quelleA-algebreB, chiamate algebre di Hilbert, in cui è vera una generalizzazione del teorema degli zeri di Hilbert. In particolare studiamo alcune proprietà che implicano cheB sia un'algebra di Hilbert e proviamo il passaggio di queste proprietà rispetto a certi cambiamenti di base. Infine studiamo alcuni anelli di frazioni dell'anello dei polinomi sopra un corpo algebricamente chiusoK ed in un insieme di indeterminate di cardinalità non inferiore a quella diK.

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Summary In this paper we study thoseA-algebrasB, named Hilbert algebras, in which a generalization of Hilbert's Nullstellensatz is verified. Particularly we look at some properties implying thatB is an Hilbert algebra and we prove the passage of this property with respect to certain base change. At last we study some rings of fractions of the polynomial ring generated over an algebrically closed fieldK by a set of indeterminates with cardinality greater or equal then the cardinality ofK.

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Lavoro eseguito nell'ambito dei gruppi di ricerca del C.N.R.