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A first product of this European project was a tool for scoring chick quality. A link was established between chick quality and embryonic physiological parameters such as heat production. Eggs from broiler breeders that give rise to rapidly growing broilers have a different embryonic development that may need modified incubation conditions. Within genotypes, better chick quality induces better liveability and faster growth in broiler production. Extensive data on broiler breeder production were generated. Feed restriction was necessary to maintain welfare and reproduction at acceptable levels in standard broiler breeders. The dw-experimental genotype (E) was more tolerant to ad libitum feeding. If an alternative to feed restriction had to be found, the use of a dw genotype with less severe feed restriction could be adopted. Fibre per se, or partial feed restriction during the growing period, only compensated to a small extent for the negative effects of early fast growth on later reproduction. The results of the project on behaviour did not support welfare concerns on feed restriction. They confirmed the hypothesis that environmental pecking is a displacement activity rather than a sign of frustration. Factors other than central control by pituitary hormones seem to be involved in the modulation of the laying rate. The local (intra-ovarian) role of growth factors such as Insulin-like Growth Factors (IGFs), Bone Morphogenetic Proteins (BMPs) and leptin are known to modulate the effect of gonadotrophins on ovarian function. For both BMPs and IGFs, feed restriction enhanced the interaction between growth factors and gonadotrophins as well as the proliferation of granulosa cells in vitro. Future genetic selection of broiler breeder production might aim at uncoupling the control of growth factors in the ovary from the selection for rapid growth to maintain or increase the growth rate of chicks without further penalising the already poor reproductive performance of broiler breeders. Putative quantitative trait loci for ovulation rate were identified in the project and may eventually facilitate selection by breeding companies for birds that could be fed enough feed to optimise their welfare.
The Medium-l Program of the Michelson Doppler Imager (MDI) instrument on board SOHO provides continuous observations of oscillation modes of angular degree, l, from 0 to ∼ 300. The initial results show that the noise in the Medium-l oscillation power spectrum is substantially lower than in ground-based measurements. This enables us to detect lower amplitude modes and, thus, to extend the range of measured mode frequencies. The MDI observations also reveal the asymmetry of oscillation spectral lines. The line asymmetries agree with the theory of mode excitation by acoustic sources localized in the upper convective boundary layer. The sound-speed profile inferred from the mean frequencies gives evidence for a sharp variation at the edge of the energy-generating core. In a thin layer just beneath the convection zone, helium appears to be less abundant than predicted by theory. Inverting the multiplet frequency splittings from MDI, we detect significant rotational shear in this thin layer.
Analysis of the X-ray spectrum of WR140 seven months after the 1993 periastron passage shows chemical abundances inconsistent with those used to model the earlier, more heavily absorbed, PV phase spectrum.
The radio emission from WR125 (WC7+O9) has faded to a new low, apparently below its stellar wind level, while continuous, variable non-thermal emission has been observed from WR146 (WC6) and WR147 (WN8).
We present the first results of the IUE monitoring campaign of the WC7+O4-5 binary system WR140. Thirty-four high-resolution short-wavelength spectra were obtained in 1979—93, i.e., over more than one orbital period of 7.9 yr. The spectra show variations in the strong resonance lines of CIV and SiIV: large variations occur at the blue edges of the absorption parts of their P-Cygni profiles just after periastron passage. The observed profile changes are discussed in terms of a velocity variation at periastron passage and/or turbulence in the sightline to the O4—5 star at this time.
New observations of the colliding wind Wolf-Rayet WC7+O4-5 binary WR140 (HD 193793) at 6 cm and 21 cm with the Westerbork Synthesis Radio Telescope are presented. They show that the 21 cm flux, in particular, rose to a sharp maximum in 1992, lagging about a year behind the 6 cm flux. After maximum, both fell simultaneously. The data are interpreted in terms of the varying circumstellar extinction to a non-thermal source in the wind interaction region due to the winds of both WC and O stars.
Transition-metal-hydrogen complexes have been introduced into bulk Si samples that contained Pt, Au, or Rh by the indiffusion of hydrogen at 1250°C from H2 gas. The structure and electrical properties of a PtH2 complex in Si have been studied by vibrational spectroscopy and electron paramagnetic resonance (EPR). The PtH2 complex has been found to introduce two levels in the Si bandgap. There is one paramagnetic charge state for which EPR provides detailed structural information and two nonparamagnetic charge states. The hydrogen vibrations of all three charge states of PtH2 have been assigned. In addition to the PtH2 complex, the hydrogen vibrations of several additional complexes in Si samples that contain hydrogen and Pt, Au, or Rh have been identified.
A number of Wolf-Rayet stars show variations of up to a factor of ten in their infrared emission on timescales of months to years while their photospheric luminosities remain unchanged. This can be interpreted in terms of variation in the rates at which dust grains form in their stellar winds. Our data show variable circumstellar dust emission from WR 70 (HD 137603), with an episode of enhanced dust formation in early 1989, and fading of emission by dust formed around WR 48a (in 1979) and WR 19 some time before our first observation in 1988. We consider their relation to WR 140 (HD 193793), which forms dust in its wind for a few months at intervals of 7.94 years.
We present 1 – 3.4 μm spectra of six Wolf-Rayet stars: WR 146 (WC4), WR 111 (WC5), WR 86 (WC7), WR 140 (WC7+O4), WR 135 (WC8) and WR 88 (WC9). Examination of the relative strengths of the emission lines has enabled us to make over 20 new line identifications. Recombination analyses of the carbon and helium lines yield C/He abundance ratios much in excess of the solar value and correlated with spectral subtype.
Optical and IR spectroscopy of two galactic objects previously considered to be extreme late WN stars (van der Hucht et al., 1984), LSS4005 (formerly tentatively listed as WR85a) and NaStl (WR122), show both objects not to be WR stars, but Ofpe/WN- or B[e]-like objects.
In 1985 April, the WC7+abs star HD 193793 was observed, using UKIRT, to have brightened significantly in the infrared owing to the formation of a new dust shell. Examination of infrared photometry of this star since 1979 and previously published data indicates that the dust formation occurs at intervals of 7.9 years. Phasing the published radial velocities of the absorption line component with this period confirms that it is a member of an eccentric (e = 0.7−0.8) binary system having periastron passage shortly before dust formation. The X-ray spectrum also changed between 1984 and 1985 in becoming significantly “harder” while the non-thermal radio source disappeared, both changes indicating greater extinction. This suggests a model wherein the source of the non-thermal radio and X-ray emission moves deep into the Wolf-Rayet wind.
IRAS PSC. LRS. and CPC observations of Wolf-Rayet stars are used as diagnostics of hot circumstellar dust shells, cool dust in WR ring nebulae, the Ne/He abundance ratio, and the interstellar extinction. In two cases the IR energy distributions are indicative of a WR planetary nucleus status rather than a Population-I WR status.
In a recent IR photometric survey of late-type WC and WN stars, it was discovered that not only most WC8-10 stars have circumstellar dust shells, but that two extreme late-type WN stars also have strong IR excesses from circumstellar dust. The latter shells appear to have significantly different density distributions. In this paper the possibility of an evolutionary sequence is suggested.
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