933 research outputs found

    Spatial variation and temporal trends of testicular cancer in Great Britain

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    Increases in testicular cancer incidence have been reported in several countries over a long period. Geographical variability has also been reported in some studies. We have investigated temporal trends and spatial variation of testicular cancer at ages 20–49 in Britain. Temporal trends in testicular cancer incidence were examined, 1974 to 1991 and in mortality, 1981–1997. Spatial variation in incidence was analysed across electoral wards, 1975 to 1991. We used Poisson regression to examine for regional and socio-economic effects and Bayesian mapping techniques to analyse small-area spatial variability. Incidence increased from 6.5 to 11.1 per 100 000 in men at ages 20–34, and from 5.6 to 9.7 per 100 000 in men at ages 35–49, while mortality declined by 50% in both age groups. Risks of testicular cancer varied across regional cancer registries, ranging from 0.79 (95% CI: 0.73–0.84) to 1.32 (95% CI: 1.25–1.38), and was higher in the most affluent compared with the most deprived areas. Analyses within 2 regions (one predominantly urban, the other predominantly rural) did not indicate any localized geographical clustering. The increasing incidence contrasted with a decreasing mortality over time in Great Britain, similar to that found in other countries. The higher risk in more affluent areas is not consistent with findings on social class at the individual level. The absence of any marked geographical variability at small area scale argues against a geographically varying environmental factor operating strongly in the aetiology of testicular cancer. © 2001 Cancer Research Campaign http://www.bjcancer.co

    Benefit of woodland and other natural environments for adolescents’ cognition and mental health

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    Epidemiological studies have established positive associations of urban nature with cognitive development and mental health. However, why specifically these health benefits are received remains unclear, especially in adolescents. We used longitudinal data in a cohort of 3,568 adolescents aged 9 to 15 years at 31 schools across London, UK, to examine the associations between natural-environment types and adolescents’ cognitive development, mental health and overall well-being. We characterized natural-environment types in three tiers, where natural space was distinguished into green and blue space, and green space was further distinguished into woodland and grassland. We showed that, after adjusting for other confounding variables, higher daily exposure to woodland, but not grassland, was associated with higher scores for cognitive development and a lower risk of emotional and behavioural problems for adolescents. A similar but smaller effect was seen for green space, but not blue space, with higher scores for cognitive development. Our results suggest that urban planning decisions to optimize ecosystem benefits linked to cognitive development and mental health should carefully consider the type of natural environment included

    Irregular Wakimoto modules and the Casimir connection

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    We study some non-highest weight modules over an affine Kac-Moody algebra at non-critical level. Roughly speaking, these modules are non-commutative localizations of some non-highest weight "vacuum" modules. Using free field realization, we embed some rings of differential operators in endomorphism rings of our modules. These rings of differential operators act on a localization of the space of coinvariants of any module over the Kac-Moody algebra with respect to a certain level subalgebra. In a particular case this action is identified with the Casimir connection.Comment: Final version, available at Springerlink.co

    Limits of Gaudin algebras, quantization of bending flows, Jucys--Murphy elements and Gelfand--Tsetlin bases

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    Gaudin algebras form a family of maximal commutative subalgebras in the tensor product of nn copies of the universal enveloping algebra U(\g) of a semisimple Lie algebra \g. This family is parameterized by collections of pairwise distinct complex numbers z1,...,znz_1,...,z_n. We obtain some new commutative subalgebras in U(\g)^{\otimes n} as limit cases of Gaudin subalgebras. These commutative subalgebras turn to be related to the hamiltonians of bending flows and to the Gelfand--Tsetlin bases. We use this to prove the simplicity of spectrum in the Gaudin model for some new cases.Comment: 11 pages, references adde

    Characterization of a clinical olfactory test with an artificial nose

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    Clinical olfactory tests are used to address hyposmia/anosmia levels in patients with different types of olfactory impairments. Typically, a given test is employed clinically and then replaced by a new one after a certain period of use which can range from days to several months. There is a need to assess control quality of these tests and also for a procedure to quantify their degradation over time. In this paper we propose a protocol to employ low-cost artificial noses for the quantitative characterization of olfactory tests used in clinical studies. In particular, we discuss a preliminary study on the Connecticut Chemosensorial Clinical Research Center Test kit which shows that some odorants, as sensed by an artificial nose, seem to degrade while others are potentiated as the test ages. We also discuss the need to establish a map of correspondence between human and machine olfaction when artificial noses are used to characterize or compare human smell performance in research and clinical studies

    Comparison of UV irradiances from Aura/Ozone Monitoring Instrument (OMI) with Brewer measurements at El Arenosillo (Spain) – Part 1: Analysis of parameter influence

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    The main objective of this study is to compare the erythemal UV irradiance (UVER) and spectral UV irradiances (at 305, 310 and 324 nm) from the Ozone Monitoring Instrument (OMI) onboard NASA EOS/Aura polar sun-synchronous satellite (launched in July 2004, local equator crossing time 01:45 p.m.) with ground-based measurements from the Brewer spectrophotometer #150 located at El Arenosillo (South of Spain). The analyzed period comprises more than four years, from October 2004 to December 2008. The effects of several factors (clouds, aerosols and the solar elevation) on OMI-Brewer comparisons were analyzed. The proxies used for each factor were: OMI Lambertian Equivalent Reflectivity (LER) at 360 nm (clouds), the aerosol optical depth (AOD) at 440 nm measured from the ground-based Cimel sun-photometer (<a href="http://aeronet.gsfc.nasa.gov"target="_blank">http://aeronet.gsfc.nasa.gov</a>), and solar zenith angle (SZA) at OMI overpass time. The comparison for all sky conditions reveals positive biases (OMI higher than Brewer) 12.3% for UVER, 14.2% for UV irradiance at 305 nm, 10.6% for 310 nm and 8.7% for 324 nm. The OMI-Brewer root mean square error (RMSE) is reduced when cloudy cases are removed from the analysis, (e.g., RMSE~20% for all sky conditions and RMSE smaller than 10% for cloud-free conditions). However, the biases remain and even become more significant for the cloud-free cases with respect to all sky conditions. The mentioned overestimation is partially due to aerosol extinction influence. In addition, the differences OMI-Brewer typically decrease with SZA except days with high aerosol loading, when the bias is near constant. The seasonal dependence of the OMI-Brewer difference for cloud-free conditions is driven by aerosol climatology. <br><br> To account for the aerosol effect, a first evaluation in order to compare with previous TOMS results (Antón et al., 2007) was performed. This comparison shows that the OMI bias is between +14% and +19% for UVER and spectral UV irradiances for moderately-high aerosol load (AOD>0.25). The OMI bias is decreased by a factor of 2 (the typical bias varies from +8% to +12%) under cloud-free and low aerosol load conditions (AOD<0.1). More detailed analysis of absorbing aerosols influence on OMI bias at our station is presented in a companion paper (Cachorro et al., 2010)

    Observation of a continuous phase transition in a shape-memory alloy

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    Elastic neutron-scattering, inelastic x-ray scattering, specific-heat, and pressure-dependent electrical transport measurements have been made on single crystals of AuZn and Au_{0.52}Zn_{0.48} above and below their martensitic transition temperatures (T_M=64K and 45K, respectively). In each composition, elastic neutron scattering detects new commensurate Bragg peaks (modulation) appearing at Q = (1.33,0.67,0) at temperatures corresponding to each sample's T_M. Although the new Bragg peaks appear in a discontinuous manner in the Au_{0.52}Zn_{0.48} sample, they appear in a continuous manner in AuZn. Surprising us, the temperature dependence of the AuZn Bragg peak intensity and the specific-heat jump near the transition temperature are in favorable accord with a mean-field approximation. A Landau-theory-based fit to the pressure dependence of the transition temperature suggests the presence of a critical endpoint in the AuZn phase diagram located at T_M*=2.7K and p*=3.1GPa, with a quantum saturation temperature \theta_s=48.3 +/- 3.7K.Comment: 6 figure

    Two and Three Dimensional Incommensurate Modulation in Optimally-Doped Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta}

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    X-ray scattering measurements on optimally-doped single crystal samples of the high temperature superconductor Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} reveal the presence of three distinct incommensurate charge modulations, each involving a roughly fivefold increase in the unit cell dimension along the {\bf b}-direction. The strongest scattering comes from the well known (H, K±\pm 0.21, L) modulation and its harmonics. However, we also observe broad diffraction which peak up at the L values complementary to those which characterize the known modulated structure. These diffraction features correspond to correlation lengths of roughly a unit cell dimension, ξc\xi_c\sim20 A˚\AA in the {\bf c} direction, and of ξb\xi_b\sim 185 A˚\AA parallel to the incommensurate wavevector. We interpret these features as arising from three dimensional incommensurate domains and the interfaces between them, respectively. In addition we investigate the recently discovered incommensuate modulations which peak up at (1/2, K±\pm 0.21, L) and related wavevectors. Here we explicitly study the L-dependence of this scattering and see that these charge modulations are two dimensional in nature with weak correlations on the scale of a bilayer thickness, and that they correspond to short range, isotropic correlation lengths within the basal plane. We relate these new incommensurate modulations to the electronic nanostructure observed in Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} using STM topography.Comment: 8 pages, 8 figure
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