632 research outputs found
The cosmological co-evolution of supermassive black holes, AGN and galaxies
We model the cosmological co-evolution of galaxies and their central
supermassive black holes (BHs) within a semi-analytical framework developed on
the outputs of the Millennium Simulation (Croton et al., 2006; De Lucia &
Blaizot, 2007). In this work, we analyze the model BH scaling relations,
fundamental plane and mass function, and compare them with the most recent
observational data. Furthermore, we extend the original code developed by
Croton et al. (2006) to follow the evolution of the BH mass accretion and its
conversion into radiation, and compare the derived AGN bolometric luminosity
function with the observed one. We find, for the most part, a very good
agreement between predicted and observed BH properties. Moreover, the model is
in good agreement with the observed AGN number density in 0<z<5, provided it is
assumed that the cold gas fraction accreted by BHs at high redshifts is larger
than at low redshifts (Marulli et al., 2008).Comment: Proceedings of "The Central Kiloparsec: Active Galactic Nuclei and
Their Hosts", Ierapetra, Crete, 4-6 June, 2008. To appear in Volume 79 of the
Memorie della Societa' Astronomica Italiana. 5 pages, 4 figure
The Signaling Value of Labor Market Programs
This paper investigates how employers interpret participation in active labor market programs for hiring decisions. Drawing on signaling theory, we assume that employers use program participation as a signal for a candidate’s qualities. On the basis of a factorial survey experiment, we simulated a hiring process for two job positions, a low and mid-skilled one, in the hotel sector. Recruiters were asked to evaluate fictional candidates that differ, among other characteristics, in their participation in active labor market programs. Our results show that employers do use participation in labor market programs as a signal. Its impact can be positive as well as negative, depending on the type of job that is applied for. For low-skill positions, the impact is more positive than for mid-skilled ones. We also show that the signal “participation in a labor market program” interacts with education and, to a lesser extent, nationality. By studying interactions among signals and with job type, this article contributes both, to a better understanding of how job market signaling works as well as to the literature on labor market programs
Municipal solid waste prevention: A review of market-based instruments in six European Union countries
This article focuses on quantitative prevention of municipal solid waste among the 28 member countries of the European Union. A strict definition of waste prevention is used, including waste avoidance, waste reduction at source or in process, and product reuse, while recycling is outside the scope of this article. In order to provide a solid overview of the European situation, the study selected six countries (Belgium, Bulgaria, Italy, the Netherlands, Romania and Spain). Several selection requirements have been considered, such as geographic location or municipal solid waste per capita production trends from 1995 to 2017. A review of prevention programmes and other national strategic documents has been conducted. Extended producer responsibility, Pay-As-You-Throw schemes, Deposit-Refund Systems and Environmental Taxes implementation among the selected countries have been studied in order to understand how these market-based instruments can be used for the sake of waste prevention. Each market-based instrument has been further analysed using the Drivers Pressures State Impact Response model. Based on the results of this study, the effectiveness of market-based instruments implementation is strictly related to the context they are enforced in. It is particularly important to tailor the market-based instruments based on the implementation area. Nevertheless, market-based instruments, which are now mostly meant to boost the recycling sector of the considered Member States, should be designed to improve waste prevention performances, ensuring the achievement of the highest level of waste hierarchy promoted by the European Union
The Distance to the M31 Globular Cluster System
The distance to the centroid of the M31 globular cluster system is determined
by fitting theoretical isochrones to the observed red-giant branches of
fourteen globular clusters in M31. The mean true distance modulus of the M31
globular clusters is found to be 24.47 +/- 0.07 mag. This is consistent with
distance modulii for M31 that have been obtained using other distance
indicators.Comment: 11 pages, 2 postscript figures, uses aaspp4.sty, to be published in
the May 1998 Astronomical Journa
Sometimes needs change minds: Interests and values as determinants of attitudes towards state support for the self-employed during the COVID-19 crisis.
This contribution investigates public attitudes toward providing financial help to the self-employed, a less well-researched area in the otherwise vibrant literature on welfare state attitudes. We analyse to what extent the self-employed themselves soften their general anti-statist stance in times of need, and how the public thinks about supporting those who usually tend to oppose government interventions. To answer these questions, we study public attitudes towards providing financial aid to the self-employed during the lockdowns adopted in response to the COVID pandemic in Switzerland, using survey data collected in the spring and in the autumn of 2020. The results show that most respondents favour the provision of financial support. In addition, the self-employed are the staunchest supporters of the more generous forms of help, like non-refundable payments. We conclude that, when exposed to significant economic risk, need and interests override ideological preferences for less state intervention
LCA to Estimate the Environmental Impact of Dairy Farms: A Case Study
Intensive farming is responsible for extreme environmental impacts under different aspects, among which global warming represents a major reason of concern. This is a quantitative problem linked to the farm size and a qualitative one, depending on farming methods and land management. The dairy sector is particularly relevant in terms of environmental impact, and new approaches to meeting sustainability goals at a global scale while meeting society's needs are necessary. The present study was carried out to assess the environmental impact of dairy cattle farms based on a life cycle assessment (LCA) model applied to a case study. These preliminary results show the possibility of identifying the most relevant impacts in terms of supplied products, such as animal feed and plastic packaging, accounting for 19% and 15% of impacts, respectively, and processes, in terms of energy and fuel consumption, accounting for 53% of impacts overall. In particular, the local consumption of fossil fuels for operations within the farm represents the most relevant item of impact, with a small margin for improvement. On the other hand, remarkable opportunities to reduce the impact can be outlined from the perspective of stronger partnerships with suppliers to promote the circularity of packaging and the sourcing of animal feed. Future studies may include the impact of drug administration and the analysis of social aspects of LCA
2MASS NIR photometry for 693 candidate globular clusters in M31 and the Revised Bologna Catalogue
We have identified in the 2MASS database 693 known and candidate globular
clusters in M31. The 2MASS J,H,K magnitudes of these objects have been
transformed to the same homogeneous photometric system of existing near
infrared photometry of M31 globulars, finally yielding J,H,K integrated
photometry for 279 confirmed M31 clusters, 406 unconfirmed candidates and 8
objects with controversial classification. Of these objects 529 lacked any
previous estimate of their near infrared magnitudes. The newly assembled near
infrared dataset has been implemented into a revised version of the Bologna
Catalogue of M31 globulars, with updated optical (UBVRI) photometry taken, when
possible, from the most recent sources of CCD photometry available in the
literature and transformed to a common photometric system. The final Revised
Bologna Catalogue (available in electronic form) is the most comprehensive list
presently available of confirmed and candidate M31 globular clusters, with a
total of 1164 entries. In particular, it includes 337 confirmed GCs, 688 GC
candidates, 10 objects with controversial classification, 70 confirmed
galaxies, 55 confirmed stars, and 4 HII regions lying within ~3 deg. from the
center of the M31 galaxy. Using the newly assembled database we show that the
V-K color provides a powerful tool to discriminate between M31 clusters and
background galaxies, and we identify a sample of 83 globular cluster
candidates, which is not likely to be contaminated by misclassified galaxies.Comment: 9 pages,5 figures,accepted for publication in Astronomy &
Astrophysics ASCII (commented) version of the tables 2,3,4 are available at
http://www.bo.astro.it/M3
Perpendicular momentum injection by lower hybrid wave in a tokamak
The injection of lower hybrid waves for current drive into a tokamak affects
the profile of intrinsic rotation. In this article, the momentum deposition by
the lower hybrid wave on the electrons is studied. Due to the increase in the
poloidal momentum of the wave as it propagates into the tokamak, the parallel
momentum of the wave increases considerably. The change of the perpendicular
momentum of the wave is such that the toroidal angular momentum of the wave is
conserved. If the perpendicular momentum transfer via electron Landau damping
is ignored, the transfer of the toroidal angular momentum to the plasma will be
larger than the injected toroidal angular momentum. A proper quasilinear
treatment proves that both perpendicular and parallel momentum are transferred
to the electrons. The toroidal angular momentum of the electrons is then
transferred to the ions via different mechanisms for the parallel and
perpendicular momentum. The perpendicular momentum is transferred to ions
through an outward radial electron pinch, while the parallel momentum is
transferred through collisions.Comment: 22 pages, 4 figure
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