1,086 research outputs found
Carbon and Oxygen in Nearby Stars: Keys to Protoplanetary Disk Chemistry
We present carbon and oxygen abundances for 941 FGK stars-the largest such
catalog to date. We find that planet-bearing systems are enriched in these
elements. We self-consistently measure C/O, which is thought to play a key role
in planet formation. We identify 46 stars with C/O \geq 1.00 as potential hosts
of carbon-dominated exoplanets. We measure a downward trend in [O/Fe] versus
[Fe/H] and find distinct trends in the thin and thick disks, supporting the
work of Bensby et al. Finally, we measure sub-solar C/O = 0.40+0.11 - 0.07, for
WASP-12, a surprising result as this star is host to a transiting hot Jupiter
whose dayside atmosphere was recently reported to have C/O \geq 1 by
Madhusudhan et al. Our measurements are based on 15,000 high signal-to-noise
spectra taken with the Keck 1 telescope as part of the California Planet
Search. We derive abundances from the [O I] and C I absorption lines at
{\lambda} = 6300 and 6587 {\AA} using the SME spectral synthesizer.Comment: 108 pages (including appendix), 16 figures, 6 table
Changing times in England: the influence on geography teachers’ professional practice
School geography in England has been characterised as a pendulum swinging between policies that emphasise curriculum and pedagogy alternately. In this paper, I illustrate the influence of these shifts on geography teacher's professional practice, by drawing on three “moments” from my experience as a student, teacher and teacher educator. Barnett's description of teacher professionalism as a continuous project of “being” illuminates how geography teachers can adapt to competing influences. It reflects teacher professionalism as an unfinished project, which is responsive, but not beholden, to shifting trends, and is informed by how teachers frame and enact policies. I argue that recognising these contextual factors is key to supporting geography teachers in “being” geography education professionals. As education becomes increasingly competitive on a global scale, individual governments are looking internationally for “solutions” to improve educational rankings. In this climate, the future of geography education will rest on how teachers react locally to international trends. Geography teacher educators can support this process by continuing to inform the field through meaningful geography education research, in particular in making the contextual factors of their research explicit. This can be supported through continued successful international collaboration in geography education research
Determination of management and topographic influences on the balance between resident and 'Grasslands Huia' white clover (Trifolium repens ) in an upland pasture using isozyme analysis
An investigation was made during 1988 to test the hypothesis that ‘Grasslands Huia’ white clover
(Trifolium repens L.) could be eliminated under close sheep grazing. The effects of grazing
management, topography and fertilizer on the contribution of Huia plants to the white clover
population in an 85 ha experimental upland pasture ecosystem in the southern North Island, New
Zealand (lat. 40° 20′ S, long. 175° 50′ E, 125–350 m altitude) were quantified 11 years after
oversowing. Replicated sampling sites (108 in total) were located on nine combinations of slope and
aspect within grazing management treatments comprising rotational grazing with cattle (RC),
rotational grazing with sheep (RS) and continuous grazing with sheep (CS), with high and low
fertilizer treatments in each case. White clover occurrence, leaf area, phosphoglucoisomerase-2
(PGI-2) allele frequencies and the proportion of Grasslands Huia plants in the white clover population
were determined at each site. White clover frequency was lower on steeper slopes. Aspect, slope and
grazing management affected area of individual clover leaves. The proportion of Huia plants in the
white clover population averaged 54·9, 49·0 and 33·6% for RC, RS and CS, respectively (P < 0·039,
5 D.F.). Fertilizer and topography did not affect the proportion of Huia. It was concluded that
although Huia did persist after 11 years of close sheep grazing, its contribution to the total white
clover population was unsatisfactory in some cases, and use of better adapted cultivars is suggested.</jats:p
Tumor site immune markers associated with risk for subsequent basal cell carcinomas.
BackgroundBasal cell carcinoma (BCC) tumors are the most common skin cancer and are highly immunogenic.ObjectiveThe goal of this study was to assess how immune-cell related gene expression in an initial BCC tumor biopsy was related to the appearance of subsequent BCC tumors.Materials and methodsLevels of mRNA for CD3ε (a T-cell receptor marker), CD25 (the alpha chain of the interleukin (IL)-2 receptor expressed on activated T-cells and B-cells), CD68 (a marker for monocytes/macrophages), the cell surface glycoprotein intercellular adhesion molecule-1 (ICAM-1), the cytokine interferon-γ (IFN-γ) and the anti-inflammatory cytokine IL-10 were measured in BCC tumor biopsies from 138 patients using real-time PCR.ResultsThe median follow-up was 26.6 months, and 61% of subjects were free of new BCCs two years post-initial biopsy. Patients with low CD3ε CD25, CD68, and ICAM-1 mRNA levels had significantly shorter times before new tumors were detected (p = 0.03, p = 0.02, p = 0.003, and p = 0.08, respectively). Furthermore, older age diminished the association of mRNA levels with the appearance of subsequent tumors.ConclusionsOur results show that levels of CD3ε, CD25, CD68, and ICAM-1 mRNA in BCC biopsies may predict risk for new BCC tumors
Exploring Science Teaching Efficacy of CASE Curriculum Teachers: A Post-Then-Pre Assessment
Beliefs Instrument (STEBI). The population included all teachers completing a CAS
Measuring the Potential Power Elite in the UK and Sweden
This paper proposes a methodology for using survey data to understand the composition of elites, through analysing the pool of potential members. An occupational-based measure of ‘potential power elite' (PPE) is created and compared with other measures of occupational advantage. It is argued that this measure can be utilised to explore if the processes causing certain social groups to be under-represented in elite positions are around selection or the population recruited from. We provide analysis of elite positions in the UK and Sweden, demonstrating differences in terms of the potential pool of elite members and the occupational histories of people of those employed in roles associated with elite recruitment. We argue that understanding the composition of the PPE provides a more nuanced analysis of the processes of meritocracy in accessing positions of power and social influence
The economic and innovation contribution of universities: a regional perspective
Universities and other higher education institutions (HEIs) have come to be regarded as key sources of knowledge utilisable in the pursuit of economic growth. Although there have been numerous studies assessing the economic and innovation impact of HEIs, there has been little systematic analysis of differences in the relative contribution of HEIs across regions. This paper provides an exploration of some of these differences in the context of the UK’s regions. Significant differences are found in the wealth generated by universities according to regional location and type of institution. Universities in more competitive regions are generally more productive than those located in less competitive regions. Also, traditional universities are generally more productive than their newer counterparts, with university productivity positively related to knowledge commercialisation capabilities. Weaker regions tend to be more dependent on their universities for income and innovation, but often these universities under-perform in comparison to counterpart institutions in more competitive regions. It is argued that uncompetitive regions lack the additional knowledge infrastructure, besides universities, that are more commonly a feature of more competitive regions
Incorporating New Technologies Into Toxicity Testing and Risk Assessment: Moving From 21st Century Vision to a Data-Driven Framework
Based on existing data and previous work, a series of studies is proposed as a basis toward a pragmatic early step in transforming toxicity testing. These studies were assembled into a data-driven framework that invokes successive tiers of testing with margin of exposure (MOE) as the primary metric. The first tier of the framework integrates data from high-throughput in vitro assays, in vitro-to-in vivo extrapolation (IVIVE) pharmacokinetic modeling, and exposure modeling. The in vitro assays are used to separate chemicals based on their relative selectivity in interacting with biological targets and identify the concentration at which these interactions occur. The IVIVE modeling converts in vitro concentrations into external dose for calculation of the point of departure (POD) and comparisons to human exposure estimates to yield a MOE. The second tier involves short-term in vivo studies, expanded pharmacokinetic evaluations, and refined human exposure estimates. The results from the second tier studies provide more accurate estimates of the POD and the MOE. The third tier contains the traditional animal studies currently used to assess chemical safety. In each tier, the POD for selective chemicals is based primarily on endpoints associated with a proposed mode of action, whereas the POD for nonselective chemicals is based on potential biological perturbation. Based on the MOE, a significant percentage of chemicals evaluated in the first 2 tiers could be eliminated from further testing. The framework provides a risk-based and animal-sparing approach to evaluate chemical safety, drawing broadly from previous experience but incorporating technological advances to increase efficiency
Genome-wide linkage analysis of 972 bipolar pedigrees using single-nucleotide polymorphisms.
Because of the high costs associated with ascertainment of families, most linkage studies of Bipolar I disorder (BPI) have used relatively small samples. Moreover, the genetic information content reported in most studies has been less than 0.6. Although microsatellite markers spaced every 10 cM typically extract most of the genetic information content for larger multiplex families, they can be less informative for smaller pedigrees especially for affected sib pair kindreds. For these reasons we collaborated to pool family resources and carried out higher density genotyping. Approximately 1100 pedigrees of European ancestry were initially selected for study and were genotyped by the Center for Inherited Disease Research using the Illumina Linkage Panel 12 set of 6090 single-nucleotide polymorphisms. Of the ~1100 families, 972 were informative for further analyses, and mean information content was 0.86 after pruning for linkage disequilibrium. The 972 kindreds include 2284 cases of BPI disorder, 498 individuals with bipolar II disorder (BPII) and 702 subjects with recurrent major depression. Three affection status models (ASMs) were considered: ASM1 (BPI and schizoaffective disorder, BP cases (SABP) only), ASM2 (ASM1 cases plus BPII) and ASM3 (ASM2 cases plus recurrent major depression). Both parametric and non-parametric linkage methods were carried out. The strongest findings occurred at 6q21 (non-parametric pairs LOD 3.4 for rs1046943 at 119 cM) and 9q21 (non-parametric pairs logarithm of odds (LOD) 3.4 for rs722642 at 78 cM) using only BPI and schizoaffective (SA), BP cases. Both results met genome-wide significant criteria, although neither was significant after correction for multiple analyses. We also inspected parametric scores for the larger multiplex families to identify possible rare susceptibility loci. In this analysis, we observed 59 parametric LODs of 2 or greater, many of which are likely to be close to maximum possible scores. Although some linkage findings may be false positives, the results could help prioritize the search for rare variants using whole exome or genome sequencing
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