30,134 research outputs found

    Radio Properties of NLS1s

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    While NLS1s have been studied intensively at X-ray and optical wavelengths, comparatively little is known about their characteristics in the radio band. Therefore, we have carried out an investigation of the radio luminosities, source sizes, spectral index distribution, and variability of a large, uniformly selected sample of NLS1s. Our results indicate that, in some respects, the radio properties of NLS1s differ significantly from those of classical Seyfert galaxies. Radio observations of NLS1s may thus provide important clues regarding the nature of their nuclear activity.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

    Individual Budgets : Lessons from Early Users' Experiences

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    Within the context of modernization, there has been a trend towards 'cash-for-care' schemes designed to bring choice and control closer to the service user. In England, Individual Budgets (IBs) are being piloted, with the aim of promoting personalized support for disabled people and other users of social care services. This paper reports on the experiences and outcomes of early IB users two to three months after first being offered an IB. The users included adults with physical/sensory impairments, learning difficulties, mental health problems and older people. Semi-structured interviews were carried out with nine service users and five proxies. The findings suggest that IBs have the potential to be innovative and life-enhancing. However, achieving this potential in practice depends on a range of other factors, including changes in the routine practices and organizational culture of adult social care services and ensuring users have access to appropriate documentation and support. Any conclusions drawn from the experiences of these early IB users must be treated with caution. The findings nevertheless indicate some of the issues that will need to be addressed as IBs are implemented more widely to replace conventional forms of adult social care provision

    Globular Cluster Formation in the Virgo Cluster

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    Metal poor globular clusters (MPGCs) are a unique probe of the early universe, in particular the reionization era. Systems of globular clusters in galaxy clusters are particularly interesting as it is in the progenitors of galaxy clusters that the earliest reionizing sources first formed. Although the exact physical origin of globular clusters is still debated, it is generally admitted that globular clusters form in early, rare dark matter peaks (Moore et al. 2006; Boley et al. 2009). We provide a fully numerical analysis of the Virgo cluster globular cluster system by identifying the present day globular cluster system with exactly such early, rare dark matter peaks. A popular hypothesis is that that the observed truncation of blue metal poor globular cluster formation is due to reionization (Spitler et al. 2012; Boley et al. 2009; Brodie & Strader 2006); adopting this view, constraining the formation epoch of MPGCs provides a complementary constraint on the epoch of reionization. By analyzing both the line of sight velocity dispersion and the surface density distribution of the present day distribution we are able to constrain the redshift and mass of the dark matter peaks. We find and quantify a dependence on the chosen line of sight of these quantities, whose strength varies with redshift, and coupled with star formation efficiency arguments find a best fitting formation mass and redshift of ≃5×108M⊙\simeq 5 \times 10^8 \rm{M}_\odot and z≃9z\simeq 9. We predict ≃300\simeq 300 intracluster MPGCs in the Virgo cluster. Our results confirm the techniques pioneered by Moore et al. (2006) when applied to the the Virgo cluster and extend and refine the analytic results of Spitler et al. (2012) numerically.Comment: 13 Pages, 13 Figures, submitted to MNRA

    Reforming OPIC for the 21st Century

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    The mission of the Overseas Private Investment Corporation (OPIC)--created in 1969 through an amendment to the Foreign Assistance Act--is "to mobilize and facilitate the participation of United States private capital and skills in the economic and social development of less developed countries and areas, and countries in transition from nonmarket to market economies, thereby complementing the development assistance objectives of the United States." OPIC pursues this mission by insuring US investors against political risks that include expropriation, currency inconvertibility, and political violence; by financing US investors overseas through loans and loan guarantees; and by providing credits to private investment funds that make equity investments in businesses in underdeveloped countries and regions.

    A new magnetic white dwarf : PG2329+267

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    We have discovered that the white dwarf PG 2329+267 is magnetic, and assuming a centered dipole structure, has a dipole magnetic field strength of approximately 2.3MG. This makes it one of only approximately 4% of isolated white dwarfs with a detectable magnetic field. Linear Zeeman splitting as well as quadratic Zeeman shifts are evident in the hydrogen Balmer sequence and circular spectropolarimetry reveals 10% circular polarisation in the two displaced sigma components of Halpha. We suggest from comparison with spectra of white dwarfs of known mass that PG 2329+267 is more massive than typical isolated white dwarfs, in agreement with the hypothesis that magnetic white dwarfs evolve from magnetic chemically peculiar Ap and Bp type main sequence stars.Comment: 5 pages, with 2 encapsulated postscipts figures include

    Sealed containers in Z

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    Physical means of securing information, such as sealed envelopes and scratch cards, can be used to achieve cryptographic objectives. Reasoning about this has so far been informal. We give a model of distinguishable sealed envelopes in Z, exploring design decisions and further analysis and development of such models

    Galaxy Clusters Selected via the Sunyaev–Zel'dovich Effect in the SPTpol 100-square-degree Survey

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    We present a catalog of galaxy cluster candidates detected in 100 square degrees surveyed with the SPTpol receiver on the South Pole Telescope. The catalog contains 89 candidates detected with a signal-to-noise ratio greater than 4.6. The candidates are selected using the Sunyaev–Zel'dovich effect at 95 and 150 GHz. Using both space- and ground-based optical and infrared telescopes, we have confirmed 81 candidates as galaxy clusters. We use these follow-up images and archival images to estimate photometric redshifts for 66 galaxy clusters and spectroscopic observations to obtain redshifts for 13 systems. An additional two galaxy clusters are confirmed using the overdensity of near-infrared galaxies only and are presented without redshifts. We find that 15 candidates (18% of the total sample) are at redshift z ≄ 1.0, with a maximum confirmed redshift of z_(max) = 1.38±0.10. We expect this catalog to contain every galaxy cluster with M_(500c) > 2.6×10Âč⁎M⊙h⁻Âč₇₀ and z > 0.25 in the survey area. The mass threshold is approximately constant above z = 0.25, and the complete catalog has a median mass of approximately M_(500c) > 2.7×10Âč⁎M⊙h⁻Âč₇₀. Compared to previous SPT works, the increased depth of the millimeter-wave data (11.2 and 6.5 ÎŒK-arcmin at 95 and 150 GHz, respectively) makes it possible to find more galaxy clusters at high redshift and lower mass

    Developing the EU Farm Accountancy Data Network to derive indicators around the sustainable use of nitrogen and phosphorus at farm level.

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    peer-reviewedThis study uses a national farm survey which is part of the European Union (EU) Farm Accountancy Data Network (FADN) to develop environmental sustainability indicators in the use of nitrogen (N) and phosphorus (P) across a range of farm systems in the Republic of Ireland. Farm level micro data were used to calculate all inputs and outputs of N and P that cross the farm gate and to derive balances (kg ha-1) and overall use efficiencies across 827 farms in 2012. The sample is populated weighted to represents 71,480 farms nationally. Results indicated an average N balance of 71.0 kg ha-1 and use efficiency of 36.7% across the nationally representative sample. Nitrogen balances were between two and four times higher across specialist dairy farms compared to livestock rearing and specialist tillage systems. Nitrogen use efficiency was generally lowest across milk producing systems compared to livestock rearing and tillage systems. Phosphorus balance and use efficiency averaged 4.7 kg ha-1 and 79.6% respectively across the sample. Specialist tillage and dairying farms had higher average P balances compared to other livestock based systems. The approach developed in this analysis will form the benchmark for temporal analysis across these indicators for future nutrient balance and efficiency trends and could assist other members of the EU FADN to develop similar nationally representative indicators.Department of Agriculture, Food and the Marin
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