Luminous blue variables as the progenitors of supernovae with quasi-periodic radio modulations

The interaction between supernova ejecta and circumstellar matter, arising from previous episodes of mass loss, provides us with a means of constraining the progenitors of supernovae. Radio observations of a number of supernovae show quasi-periodic deviations from a strict power-law decline at late times. Although several possibilities have been put forward to explain these modulations, no single explanation has proven to be entirely satisfactory. Here we suggest that Luminous blue variables undergoing S-Doradus type variations give rise to enhanced phases of mass loss that are imprinted on the immediate environment of the exploding star as a series of density enhancements. The variations in mass loss arise from changes in the ionization balance of Fe, the dominant ion that drives the wind. With this idea, we find that both the recurrence timescale of the variability and the amplitude of the modulations are in line with the observations. Our scenario thus provides a natural, single-star explanation for the observed behaviour that is, in fact, expected on theoretical grounds.

Between the devil and the deep blue sea: Nationality, power and symbolic trade-offs among evangelical Protestants in contemporary Northern Ireland

National identity is symbolically complex configuration, with shifts of emphasis and reprioritisations of content negotiated in contexts of power. This paper shows how they occur in one post-conflict situation - Northern Ireland - among some of the most extreme of national actors - evangelical Protestants. In-depth interviews reveal quite radical shifts in the content of their British identity and in their understanding of and relation to the Irish state, with implications for their future politics. The implications for understanding ethno-religious nationalism, nationality shifts and the future of Northern Ireland are drawn out.

Early birds are sexy: male age, dawn song and extrapair paternity in blue tits, Cyanistes (formerly Parus) caeruleus

Sexual selection theory predicts that signals reflecting the relative quality of individuals should be used in mate choice. Females could base their choice of copulation partners on male secondary sexual traits that honestly signal male age, as predicted by the age-based indicator mechanism. Studies have shown that female blue tits prefer older males and that aspects of dawn song reflect male quality, but it remains unknown whether dawn song characteristics correlate with male age. We compared dawn song characteristics of second-year (SY) and older (ASY) male blue tits (cross-sectional analysis), and tested for age-related changes within individuals (longitudinal analysis) and differential overwinter survival of SY males. We further investigated the relation between dawn song and paternity gain and loss. We found that ASY male blue tits began to sing earlier relative to sunrise than did SY males. This difference in the onset of dawn singing was due to age-related changes in individual performance rather than differential survival of individuals with varying expression of the trait. Males that began to sing earlier at dawn had more mating partners, and were more likely to gain extrapair paternity. Our findings suggest that the onset of dawn song can provide a simple mechanism for females to assess the relative quality of their mate and of neighbouring males. We propose that females use the onset of singing as a cue for their choice of extrapair partners. (c) 2006 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Experimentally elevated plasma testosterone levels do not influence singing behaviour of male blue tits (Parus caeruleus) during the early breeding season

Sexual selection theory suggests that females might prefer males on the basis of testosterone (T)-dependent secondary sexual traits such as song. Correlational studies have linked high plasma T-levels to high diurnal song output. This has been confirmed in experiments where T-levels were kept high at times when natural T-levels have decreased. However, surprisingly little is known about the relation between T-levels during the early breeding season and song. In many passerine birds males sing at a high rate at dawn early in the breeding season, referred to as the dawn chorus. In blue tits (Parus caeruleus), the dawn chorus coincides with the fertile period of the female, whereas diurnal song occurs throughout the breeding season. Previous studies on blue tits showed that characteristics of the dawn chorus correlate with male reproductive success. We experimentally elevated plasma T-levels in male blue tits during the pre-fertile and fertile period. Our aim was to test whether increased plasma T-levels affect dawn song characteristics and increase the amount of diurnal song. Although T-implants successfully raised circulating T-levels, we did not find any difference between T- and control males in temporal performance measures of dawn song or in diurnal song output. Our results suggest that either there is no direct causal link between song output or quality and individual T-levels, or experimental manipulations of T-levels using implants do not permit detection of such effects during the early breeding season. Although we cannot exclude that individual T-levels are causally linked to other (e.g. structural) song parameters, our results cast doubt on T-dependence as the mechanisms that enforces honesty on song as a sexually selected trait.

The natural plasma testosterone profile of male blue tits during the breeding season and its relation to song output

In male birds, the gonadal hormone testosterone (T) is known to influence territorial and mating behaviour. Plasma levels of T show seasonal fluctuations which vary in relation to mating system and social instability. First, we determined the natural T profile of male blue tits Parus caeruleus during the breeding season. We found that plasma levels of T increased at the onset of nest building. Thus, the increase in circulating T was not associated with territory establishment, nor with the fertile period of the males' mates. In most individuals, T levels dropped to values close to zero during the period of chick feeding. Second, we investigated the relationship between plasma levels of T and male age, size, and singing behaviour. During the mating period, T levels did not differ between 1 yr old and older males and did not correlate with body size or condition. However, song output during the dawn chorus tended to be positively correlated with T levels. Therefore, if high T levels are costly, song output might be an honest indicator of male quality in blue tits. Finally, we show that plasma levels of T are significantly higher during the night than during the day. This pattern has also been observed in captive non-passerine birds, but its functional significance remains unknown.

YF[MoO4] and YCl[MoO4]: Two halide derivatives of yttrium ortho-oxomolybdate: Syntheses, structures, and luminescence properties

The halide derivatives of yttrium ortho-oxomolybdate YX[MoO4] (X = F, Cl) both crystallize in the monoclinic system with four formula units per unit cell. YF[MoO4] exhibits a primitive cell setting (space group P2(1)/c, a = 519.62(2) pm, b = 1225.14(7) pm, c = 663.30(3) pm, beta = 112.851(4)degrees), whereas the lattice of YCl[MoO4] shows face-centering (space group C2/m; a = 1019.02(5) pm, b = 720.67(4) pm, c = 681.50(3) pm, beta = 107.130(4)degrees). The two compounds each contain crystallographically unique Y3+ cations, which are found to have a coordination environment of six oxide and two halide anions. In the case of YF[MoO4], the coordination environment is seen as square antiprisms, and for YCl[MoO4], trigon-dodecahedra. are found. The discrete tetrahedral [MoO4](2-) units of the fluoride derivative are exclusively bound by six terminal Y3+ cations, while those of the chloride compound show a 5-fold coordination around the tetrahedra with one edge-bridging and four terminal Y3+ cations. The halide anions in each compound exhibit a coordination number of two, building up isolated planar rhombus-shaped units according to [Y2F2](4+) in YF[MoO4] and [Y2Cl2](4+) in YCl[MoO4], respectively. Both compounds were synthesized at high temperatures using Y2O3, MoO3, and the corresponding yttrium trihalide in a molar ratio of 1:3:1. Single crystals of both are insensitive to moist air and are found to be coarse shaped and colorless with optical band gaps situated in the near UV around 3.78 eV for the fluoride and 3.82 eV for the chloride derivative. Furthermore, YF[MoO4] seems to be a suitable material for doping to obtain luminescent materials because the Eu3+-doped compound shows an intense red luminescence, which has been spectroscopically investigated.

Listening to lanthanide complexes: Determination of the intrinsic luminescence quantum yield by nonradiative relaxation

The photophysical properties of lanthanide complexes have been studied extensively; however, fundamental parameters such as the intrinsic quantum yield as well as radiative and nonradiative decay rates are difficult or even impossible to measure experimentally. Herein, a photoacoustic (PA) method is proposed to determine the intrinsic quantum yield of lanthanide complexes with lifetimes in the order of milliseconds. This method is used to determine the intrinsic quantum yields for europium (III)-containing metallomesogens as well as terbium(III) complexes. The results show that the PA signal is sensitive to both the lifetime and the ratio of the fast-to-slow heat component of the samples. It is found that there is an efficient ligand sensitization and a moderate intrinsic quantum yield for the complexes. The intrinsic quantum yield of Eu3+ in the metallomesogens exhibits an obvious increase upon the isotropic liquid to smectic A transition. The proposed PA method is quite simple, and con contribute to a clearer understanding of the photophysical processes in luminescent lanthanide complexes.

Luminescence of LaF3:Ln(3+) Nanocrystal Dispersions in Ionic Liquids

Ionic liquids were used as solvents for dispersing luminescent lanthanide-doped LaF3:Ln(3+) nanocrystals (Ln(3+) = Eu3+ and Nd3+). To increase the solubility of the inorganic nanoparticles in the ionic liquids, the nanocrystals were prepared with different stabilizing ligands, i.e., citrate, N,N,N-trimethylglycine (betaine), and lauryldimethylglycine (lauryl betaine). LaF3:5%Ln(3+) :betaine could successfully be dispersed in 1-butyl-1-methylpyrrolidinium bis(tiifluoromethylsulfonyl)imide [C(4)mpyr][Tf2N], 1-butyl-1-methylpyrrolidinium trifluoromethanesulfonate [C(4)mpyr][TfO], and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C(4)mim][Tf2N] but only in limited amounts. Red photoluminescence was observed for the europium(III)-containing nanoparticles and near-infrared luminescence for the neodymium(III)-containing systems.

Adsorption of methylene blue onto activated carbon produced from steam activated bituminous coal: A study of equilibrium adsorption isotherm.

Chemical Engineering Journal, 124 (2006) 103.

Visible-light-sensitized near-infrared luminescence from rare-earth complexes of the 9-hydroxyphenalen-1-one ligand

The unique absorption properties of the 9-hydroxyphenalen-1-one (HPHN) ligand have been exploited to obtain visible-light-sensitizable rare-earth complexes in 1: 3 and 1: 4 metal-to-ligand ratios. In both stoichiometries (1:3,tris,Ln(PHN)3;1:4, tetrakis, A[ Ln( PHN)(4)], with Ln being a trivalent rare-earth ion and A being a monovalent cation), the complexes of Nd(III),Er( III), and Yb(III) show typical near-infrared luminescence upon excitation with visible light with wavelengths up to 475 nm. The X-ray crystal structures of the tris complexes show solvent coordination to the central rare-earth ion, whereas in the tetrakis complexes, the four PHN-ligands form a protective shield around the central ion, preventing small solvent molecules from coordinating to the rare-earth ion, at least in the solid state.