Independent ferroelectric contributions and rare-earth-induced polarization reversal in multiferroic TbMn2O5

Three independent contributions to the magnetically induced spontaneous polarization of multiferroic TbMn2O5 are uniquely separated by optical second harmonic generation and an analysis in terms of Landau theory. Two of them are related to the magnetic Mn3+/4+ order and are independent of applied fields of up to 7 T. The third contribution is related to the long-range antiferromagnetic Tb3+ order. It shows a drastic decrease upon the application of a magnetic field and mediates the change of sign of the spontaneous electric polarization in TbMn2O5. The close relationship between the rare-earth long-range order and the non-linear optical properties points to isotropic Tb-Tb exchange and oxygen spin polarization as mechanism for this rare-earth induced ferroelectricity.Comment: 8 pages, 5 figure

Pretransitional phenomena in dilute crystals with first-order phase transition

Pretransitional phenomena at first-order phase transition in crystals diluted by 'neutral' impurities (analogue of nonmagnetic atoms in dilute magnets) are considered. It is shown that field dependence of order parameter becomes nonanalytical in the stability region of the ordered phase, while smeared jumps of thermodynamic parameters and anomalous (non-exponential) relaxation appear near transition temperature of pure crystal.Comment: 4 page

Spatial variation and temporal trends of testicular cancer in Great Britain

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

Finite strain Landau theory of high pressure phase transformations

The properties of materials near structural phase transitions are often successfully described in the framework of Landau theory. While the focus is usually on phase transitions, which are induced by temperature changes approaching a critical temperature T-c, here we will discuss structural phase transformations driven by high hydrostatic pressure, as they are of major importance for understanding processes in the interior of the earth. Since at very high pressures the deformations of a material are generally very large, one needs to apply a fully nonlinear description taking physical as well as geometrical nonlinearities (finite strains) into account. In particular it is necessary to retune conventional Landau theory to describe such phase transitions. In Troster et al (2002 Phys. Rev. Lett. 88 55503) we constructed a Landau-type free energy based on an order parameter part, an order parameter-(finite) strain coupling and a nonlinear elastic term. This model provides an excellent and efficient framework for the systematic study of phase transformations for a wide range of materials up to ultrahigh pressures

Short term administration of cyproterone acetate for contraception: Effects on testosterone secretion and semen characteristics in rams (Ovis aries) and bucks (Capra hircus)

Aim of study: To examine the influence of administering cyproterone acetate (CPA), at the beginning of the mating season, on the testosterone concentration and morphometric and functional characteristics of ram and buck semen.Area of study: Madrid, SpainMaterial and methods: Five rams and five bucks were intramuscularly administered 200 mg of CPA in 2 mL of olive oil twice per week - from July 1st to 31st in the rams, and from August 1st to 31st in the bucks. Five control animals of each species were administered 2 mL of olive oil. Blood samples and ejaculates analysed from the start of treatment until eight weeks after the last day of treatment.Main results: GLM-ANOVA showed the interaction species × CPA treatment to have effect (p<0.05) on sperm motility, progressive motility and acrosome integrity; and greater effect (p<0.01) on curvilinear velocity (VCL), straight-line velocity (VSL), viability, and morphological abnormalities. In both the rams and bucks, plasma testosterone levels fell from the first week from the start of CPA administration until three weeks after the end of treatment. In rams, the total sperm count, sperm motility, progressive motility, viability, morphological abnormalities, VCL and VSL were all negatively affected by the treatment (p<0.001); acrosome integrity was also affected (p<0.05). In bucks, sperm motility, progressive motility, VCL, VSL and morphological abnormalities were negatively affected (p<0.05).Research highlights: Treatment with CPA affected testosterone secretion, semen characteristics and sperm morphometry in both the rams and bucks, and thus it might be used as short term contraceptive protocol in small ruminants

‘If you look the part you’ll get the job’: should career professionals help clients to enhance their career image?

This article presents a critical exploration of the role of career professionals in supporting people to reflect on and enhance their appearance, attractiveness and self-presentation (career image). The article is conceptual and based on a review of the broader literature on career success, appearance and attractiveness. It explores the evidence for a relationship between attractiveness and career, and the authors propose a conceptual framework in which career image is comprised of three elements (interpersonal skills, aesthetic presentation and beauty). The paper examines a possible role for career professionals in relation to this and then critically examines this role and concludes with the proposition of a research agenda in this area

Comparison of UV irradiances from Aura/Ozone Monitoring Instrument (OMI) with Brewer measurements at El Arenosillo (Spain) – Part 2: Analysis of site aerosol influence

Several validation studies have shown a notable overestimation of the clear sky ultraviolet (UV) irradiance at the Earth's surface derived from satellite sensors such as the Total Ozone Mapping Spectrometer (TOMS) and the Ozone Monitoring Instrument (OMI) with respect to ground-based UV data at many locations. Most of this positive bias is attributed to boundary layer aerosol absorption that is not accounted for in the TOMS/OMI operational UV algorithm. Therefore, the main objective of this study is to analyse the aerosol effect on the bias between OMI erythemal UV irradiance (UVER) and spectral UV (305 nm, 310 nm and 324 nm) surface irradiances and ground-based Brewer spectroradiometer measurements from October 2004 to December 2008 at El Arenosillo station (37.1° N, 6.7° W, 20 m a.s.l.), with meteorological conditions representative of the South-West of Spain. <br><br> The effects of other factors as clouds, ozone and the solar elevation over this intercomparison were analysed in detail in a companion paper (Antón et al., 2010). In that paper the aerosol effects were studied making only a rough evaluation based on aerosol optical depth (AOD) information at 440 nm wavelength (visible range) without applying any correction. We have used the precise information given by single scattering albedo (SSA) from AERONET for the determination of absorbing aerosols which has allowed the correction of the OMI UV data. <br><br> An aerosol correction expression was applied to the OMI operational UV data using two approaches to estimate the UV absorption aerosol optical depth, AAOD. The first approach was based on an assumption of constant SSA value of 0.91. This approach reduces the OMI UVER bias against the reference Brewer data from 13.4% to 8.4%. Second approach uses daily AERONET SSA values reducing the bias only to 11.6%. Therefore we have obtained a 37% and 12% of improvement respectively. For the spectral irradiance at 324 nm, the OMI bias is reduced from 10.5% to 6.98% for constant SSA and to 9.03% for variable SSA. Similar results were obtained for spectral irradiances at 305 nm, and 310 nm. <br><br> Contrary to what was expected, the constant SSA approach has a greater bias reduction than variable SSA, but this is a reasonable result according to the discussion about the reliability of SSA values. Our results reflect the level of accuracy that may be reached at the present time in this type of comparison, which may be considered as satisfactory taking into account the remaining dependence on other factors. Nevertheless, improvements must be accomplished to determine reliable absorbing aerosol properties, which appear as a limiting factor for improving OMI retrievals

Mobile phone base stations and early childhood cancers: case-control study

Objective To investigate the risk of early childhood cancers associated with the mother’s exposure to radiofrequency from and proximity to macrocell mobile phone base stations (masts) during pregnancy

Diurnal cycle of precipitable water vapor over Spain

Knowledge of the diurnal cycle of precipitable water vapor (PWV) is very limited owing to the lack of data with sufficient temporal resolution. Currently, GPS receivers have proven to be a suitable technique to determine PWV diurnal variations. In this study, the annual and seasonal diurnal cycles of PWV have been obtained from GPS data for 10 locations over Spain. The minimum value of PWV is reached approximately at the same time at all the stations, ∼0430–0530 UTC, whereas the maximum is reached in the second half of the day, but with a larger dispersion of its occurrence between stations. The annual sub-daily variability ranges from 0.41 to 1.35 mm (3–7%). The highest values are recorded at the stations on the Mediterranean coast, with a doubling of the values of the stations on the Atlantic coast or inland. The winter cycle is quite similar at all locations, whereas in summer local effects are felt strongly, making the diurnal cycle quite different between stations. The PWV mean diurnal cycle is strongest in summer and weakest in spring, with a sub-daily variability of 1.34 and 0.66 mm respectively. Harmonic analysis shows that the first two harmonics can explain 97% of the variance. The diurnal (24 h) harmonic explains 85% of the variance, has mean amplitude of 0.40 mm, and the peak time is from early afternoon to evening. The semi-diurnal (12 h) harmonic is weaker, with an amplitude of 0.13 mm, and peak time between 0400 and 1000 UTC. The diurnal cycle of temperature alone would be a proxy for PWV cycle during the night, but not during the daytime. The breeze regime is the main factor responsible for the phase lag between PWV and temperature cycles during daytime. No clear correlation between the daily cycle of precipitation and PWV has been found