64 research outputs found
Climatology of Ultraviolet Budgets using Earth Observation (CUBEO): mapping UV from the perspective of risk assessments : final report
No RIVM report number in publicationThe use of satellite data to construct ground level UV-radiation maps offers a unique opportunity to investigate geographical and temporal variability of ground level UV-radiation levels related to atmospheric changes, like ozone depletion or cloud changes. The calculation of long term yearly UV-doses in combination with dose-effect models for UV-related effects, like skin cancer, further enhances the application of UV-maps as a powerful tool to support environmental assessments. This report describes the results obtained in the CUBEO-project: a Climatology of Ultraviolet Budgets using Earth Observation. The project aimed at the development and validation of UV-mapping methods that can be applied in environmental assessments. The results indicated that the satellite derived cloud correction provides accurate and representative results if the ground albedo is low. The comparison with ground based UV-measurements at different sites in Europe shows an agreement for the yearly UV-dose within 10%. An indication of the long term stability of the UV-mapping methods is obtained by means of a systematic comparison of UV-doses derived from ground based ozone and cloud data and doses derived from satellite observations over a period of nearly 20 years. The European maps of changes in UV-budgets at the ground and associated excess skin cancer risks have been reported in national and international state of the environment reports published by the National Institute of Public Health and the Environment (RIVM) and/or the European Environmental Agency (EEA). These state of the environment reports contribute to the provision of information necessary for framing and implementing sound and effective environmental policies. This investigation has been performed by order and for the account of BCRS, EU and RIVM, within the framework of the projects CUBEO and MAUVE.Beleidscommissie Remote Sensing (BCRS
Review of Geotechnical Investigations Resulting from the Roermond April 13, 1992 Earthquake
In 1987 the Engineering Geology section of the Delft University of Technology carried out a survey of the SE Netherlands to determine which areas were susceptible to liquefaction based on soil profile, groundwater levels and a Richter scale magnitude 6 earthquake along the principal rift fault through the Netherlands, the Peelrand fault system. The fault system has been active since the Triassic and forms part of the Rhine-North Sea rift system. The last major earthquake along the Peelrand fault was in 1933. Recently, in 1992, A 5.8 magnitude earthquake occurred at Roermond, near to the Dutch-German border. Though damage resulting from the earthquake was limited, remedial works to structures amounted to US$ 50 million in the Netherlands. The paper reviews geotechnical investigations associated with the earthquake carried out in the Netherlands. Much of the damage is attributed to liquefaction; excess pore pressures resulting from the earthquake caused sand vent eruptions, river-dyke failures and slope failures. Comparisons are made between the predictions of 1987 and that which occurred in 1992. Site investigation works are recording geotechnical and building data so as to allow for correlations between extents of damage, ground geotechnical profiles and building design. Models for liquefaction are reviewed to describe the slope failure as well as the sand vent phenomena. Densification of subsoil has been inferred from CPTs taken before and after the earthquake for some sites. Pile foundation damage has been investigated for buildings in Roermond for which their susceptibility to earthquake lateral forces in terms of stiffness and pile head working load is given
Let’s stop the pretence of consistent marking: exploring the multiple limitations of assessment criteria
Unreliability in marking is well documented yet we lack studies that have investigated assessors’ detailed use of assessment criteria. This project used a form of Kelly’s Repertory Grid method to examine the characteristics that 24 experienced, UK assessors notice in distinguishing between students’ performance in four contrasting subject disciplines: that is their implicit assessment criteria. Variation in the choice, ranking and scoring of criteria was evident. Inspection of the individual construct scores in a sub-sample of academic historians revealed five factors in the use of criteria that contribute to marking inconsistency. The results imply that whilst more effective and social marking processes that encourage sharing of standards in institutions and disciplinary communities may help align standards, assessment decisions at this level are so complex, intuitive and tacit that variability is inevitable. It concludes that universities should be more honest with themselves and with students and actively help students to understand that application of assessment criteria is a complex judgement and there is rarely an incontestable interpretation of their meaning
Let’s stop the pretence of consistent marking: exploring the multiple limitations of assessment criteria
Anisotropic multiple scattering in diffuse media
The multiple scattering of scalar waves in diffusive media is investigated by
means of the radiative transfer equation. This approach amounts to a
resummation of the ladder diagrams of the Born series; it does not rely on the
diffusion approximation. Quantitative predictions are obtained, concerning
various observables pertaining to optically thick slabs, such as the mean
angle-resolved reflected and transmitted intensities, and the shape of the
enhanced backscattering cone. Special emphasis is put on the dependence of
these quantities on the anisotropy of the cross-section of the individual
scatterers, and on the internal reflections due to the optical index mismatch
at the boundaries of the sample. The regime of very anisotropic scattering,
where the transport mean free path is much larger than the scattering
mean free path , is studied in full detail. For the first time the
relevant Schwarzschild-Milne equation is solved exactly in the absence of
internal reflections, and asymptotically in the regime of a large index
mismatch. An unexpected outcome concerns the angular width of the enhanced
backscattering cone, which is predicted to scale as
, in contrast with the generally
accepted law, derived within the diffusion approximation.Comment: 53 pages TEX, including 2 tables. The 4 figures are sent at reques
Worldwide variations in artificial skyglow
Despite constituting a widespread and significant environmental change,
understanding of artificial nighttime skyglow is extremely limited. Until now,
published monitoring studies have been local or regional in scope, and
typically of short duration. In this first major international compilation of
monitoring data we answer several key questions about skyglow properties.
Skyglow is observed to vary over four orders of magnitude, a range hundreds of
times larger than was the case before artificial light. Nearly all of the
study sites were polluted by artificial light. A non-linear relationship is
observed between the sky brightness on clear and overcast nights, with a
change in behavior near the rural to urban landuse transition. Overcast skies
ranged from a third darker to almost 18 times brighter than clear. Clear sky
radiances estimated by the World Atlas of Artificial Night Sky Brightness were
found to be overestimated by ~25%; our dataset will play an important role in
the calibration and ground truthing of future skyglow models. Most of the
brightly lit sites darkened as the night progressed, typically by ~5% per
hour. The great variation in skyglow radiance observed from site-to-site and
with changing meteorological conditions underlines the need for a long-term
international monitoring program
Genetic analysis of the vitamin D receptor gene in two epithelial cancers: melanoma and breast cancer case-control studies
<p>Abstract</p> <p>Background</p> <p>Vitamin D serum levels have been found to be related to sun exposure and diet, together with cell differentiation, growth control and consequently, cancer risk. Vitamin D receptor (<it>VDR</it>) genotypes may influence cancer risk; however, no epidemiological studies in sporadic breast cancer (BC) or malignant melanoma (MM) have been performed in a southern European population. In this study, the <it>VDR </it>gene has been evaluated in two epithelial cancers BC and MM.</p> <p>Methods</p> <p>We have conducted an analysis in 549 consecutive and non-related sporadic BC cases and 556 controls, all from the Spanish population, and 283 MM cases and 245 controls. Genotyping analyses were carried out on four putatively functional SNPs within the <it>VDR </it>gene.</p> <p>Results</p> <p>An association with the minor allele A of the non-synonymous SNP rs2228570 (rs10735810, <it>Fok</it>I, Met1Thr) was observed for BC, with an estimated odds ratio (OR) of 1.26 (95% CI = 1.02–1.57; p = 0.036). The synonymous variant rs731236 (<it>Taq</it>I) appeared to be associated with protection from BC (OR = 0.80, 95%CI = 0.64–0.99; p = 0.047). No statistically significant associations with MM were observed for any SNP. Nevertheless, sub-group analyses revealed an association between rs2228570 (<it>FokI</it>) and absence of childhood sunburns (OR = 0.65, p = 0.003), between the 3'utr SNP rs739837 (<it>Bgl</it>I) and fair skin (OR = 1.31, p = 0.048), and between the promoter SNP rs4516035 and the more aggressive tumour location in head-neck and trunk (OR = 1.54, p = 0.020).</p> <p>Conclusion</p> <p>In summary, we observed associations between SNPs in the <it>VDR </it>gene and BC risk, and a comprehensive analysis using clinical and tumour characteristics as outcome variables has revealed potential associations with MM. These associations required confirmation in independent studies.</p
Controlling waves in space and time for imaging and focusing in complex media
In complex media such as white paint and biological tissue, light encounters nanoscale refractive-index inhomogeneities that cause multiple scattering. Such scattering is usually seen as an impediment to focusing and imaging. However, scientists have recently used strongly scattering materials to focus, shape and compress waves by controlling the many degrees of freedom in the incident waves. This was first demonstrated in the acoustic and microwave domains using time reversal, and is now being performed in the optical realm using spatial light modulators to address the many thousands of spatial degrees of freedom of light. This approach is being used to investigate phenomena such as optical super-resolution and the time reversal of light, thus opening many new avenues for imaging and focusing in turbid medi
Two ultraviolet radiation datasets that cover China
Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes
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