Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Consequences of long-term growth at various [CO2] and temperatures on gas exchange of western wheatgrass(C3) and blue grama (C4

Continually rising atmospheric CO2 concentrations and possible climatic change may cause significant changes in plant communities. This study was undertaken to investigate gas exchange in two important grass species of the short-grass steppe, Pascopyrum smithii (western wheat-grass), C3, and Bouteloua gracilis (blue grama), C4, grown at different CO2 concentrations and temperatures. Intact soil cores containing each species were extracted from grasslands in north-eastern Colorado, USA, placed in growth chambers, and grown at combinations of two CO2 concentrations (350 and 700 μmol mol−1) and two temperature regimes (field average and elevated by 4°C). Leaf gas exchange was measured during the second, third and fourth growth seasons. All plants exhibited higher leaf CO2 assimilation rates (A) with increasing measurement CO2 concentration, with greater responses being observed in the cool-season C3 species P. smithii. Changes in the shape of intercellular CO2 response curves of A for both species indicated photosynthetic acclimation to the different growth environments. The photosynthetic capacity of P. smithii leaves tended to be reduced in plants grown at high CO2 concentrations, although A for plants grown and measured at 700μmol mol−1 CO2 was 41% greater than that in plants grown and measured at 350 μmol mol−1 CO2. Low leaf N concentration may have contributed to photosynthetic acclimation to CO2. A severe reduction in photosynthetic capacity was exhibited in P. smithii plants grown long-term at elevated temperatures. As a result, the potential response of photosynthesis to CO2 enrichment was reduced in P. smithii plants grown long-term at the higher temperature

Predestined to save the earth : The environment committee of the European parliament

Despite an increase in the influence of the European Parliament in the decision making process of the European Communities in recent years some commentators still maintain that the EP's impact on EC legislation remains marginal. Taking the Environment Committee of the European Parliament as its focus this article assesses the contribution made by the EP to EC environmental policy. While it is often asserted that the EP's legislative role in relation to environmental policy began with the Single European Act, in fact the EP performed a legislative role, including the right of initiative, before 1987; a role subsequently enhanced by the SEA. Tracing the decision making process through the various stages of initiation, consultation, cooperation and implementation, and using case studies to illustrate the Committee's contribution to this process, the variable impact of the EP upon EC environmental policy is revealed. The role of the Environment Committee as a promoter of 'environmentalism' within EC policy and institutions, and the shared consensus within the committee which assists the Committee in its efforts to influence policy is also noted

Species-level effects more important than functional group-level responses to elevated CO2: evidence from simulated turves

Using mixtures of 14 calcareous grassland plant species drawn from three functional groups, we looked at the effects of elevated atmospheric CO2 on contrasting levels of ecosystem performance (species, functional group and community). Experimental communities were subjected to ambient (?350 µmol mol?1) or elevated CO2 (?600 µmol mol?1) in controlled environments, with grazing simulated by clipping at monthly intervals for 546 days.We assessed the effect of elevated CO2 on plant performance by quantifying the productivity (biomass) and cover of component species. We also examined the effect of elevated CO2 on the vertical structure of the plant canopy. Elevated CO2 resulted in a significant increase in total community biomass only following nutrient addition. Within functional groups, non-leguminous forb species had significantly greater biomass and cover in elevated CO2 both before and after nutrient addition, although the effect was mainly due to the influence of one species (Centaurea nigra). Grasses, in contrast, responded negatively to elevated CO2, although again significant reductions in biomass and cover could mainly be ascribed to a single species (Brachypodium pinnatum). Legumes exhibited increased biomass and cover in elevated CO2 (the effects being particularly marked for Anthyllis vulneraria and Lotus corniculatus), but this response disappeared following nutrient addition. Vertical structure was little affected by CO2 treatment.We conclude that due to the idiosyncratic responses of individual species, the categorization of plants into broad functional groups is of limited use in guiding our understanding of the impacts of elevated atmospheric CO2 on plant communities.<br/

Large-scale analysis of association between polymorphisms in the transforming growth factor beta 1 gene (TGFB1) and osteoporosis: the GENOMOS study

INTRODUCTION: The TGFB1 gene which encodes transforming growth factor beta 1, is a strong candidate for susceptibility to osteoporosis and several studies have reported associations between bone mineral density (BMD), osteoporotic fractures and polymorphisms of TGFB1, although these studies have yielded conflicting results. METHODS: We investigated associations between TGFB1 polymorphisms and BMD and fracture in the GENOMOS study: a prospective multicenter study involving 10 European research studies including a total of 28,924 participants. Genotyping was conducted for known TGFB1 polymorphisms at the following sites: G-1639-A (G-800-A, rs1800468), C-1348-T (C-509-T, rs1800469), T29-C (Leu10Pro, rs1982073), G74-C (Arg25Pro, rs1800471) and C788-T (Thr263Ile, rs1800472). These polymorphisms were genotyped prospectively and methodology was standardized across research centers. Genotypes and haplotypes were related to BMD at the lumbar sine and femoral neck and fractures. RESULTS: There were no significant differences in either women or men at either skeletal site for any of the examined polymorphisms with the possible exception of a weak association with reduced BMD (-12 mg/cm2) in men with the T-1348 allele (p&lt;0.05). None of the haplotypes was associated with BMD and none of the polymorphisms or haplotypes significantly affected overall risk of fractures, however, the odds ratio for incident vertebral fracture in carriers of the rare T788 allele was 1.64 (95% CI: 1.09-2.64), p&lt;0.05. CONCLUSIONS: This study indicates that polymorphic variation in the TGFB1 gene does not play a major role in regulating BMD or susceptibility to fractures. The weak associations we observed between the C-1348-T and lumbar spine BMD in men and between C788-T and risk of incident vertebral fractures are of interest but could be chance findings and will need replication in future studie