| 1. |
- Ventura, Paolo, et al.
(författare)
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Nucleosynthesis, Mixing Processes, and Gas Pollution from AGB Stars
- 2022
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Ingår i: Universe. - : MDPI AG. - 2218-1997. ; 8:1, s. 45-
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the evolution of stars through the asymptotic giant branch, focusing on the physical mechanisms potentially able to alter the surface chemical composition and on how changes in the chemistry of the external regions affect the physical properties of the star and the duration of this evolutionary phase. We focus on the differences between the evolution of low-mass stars, driven by the growth of the core mass and by the surface carbon enrichment, and that of their higher mass counterparts, which experience hot bottom burning. In the latter sources, the variation of the surface chemical composition reflects the equilibria of the proton capture nucleosynthesis experienced at the base of the convective envelope. The pollution expected from this class of stars is discussed, outlining the role of mass and metallicity on the chemical composition of the ejecta. To this aim, we considered evolutionary models of 0.7-8 M & ODOT; stars in a wide range of metallicities, extending from the ultra-metal-poor domain to super-solar chemistries.
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| 2. |
- Batson, Emma K., et al.
(författare)
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Effects of Helium Ion Exposure on the Single-Photon Sensitivity of MgB $_{2}$ and NbN Detectors
- 2024
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Ingår i: IEEE Transactions on Applied Superconductivity. - 1558-2515 .- 1051-8223. ; 34:7
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Tidskriftsartikel (refereegranskat)abstract
- Improving the scalability, reproducibility, and operating temperature of superconducting nanowire single photon detectors (SNSPDs) has been a major research goal since the devices were first proposed. The recent innovation of helium-ion irradiation as a post-processing technique for SNSPDs could enable high detection efficiencies to be more easily reproducible, but is still poorly understood. Additionally, fabricating detectors at micron-wide scales from high-T$_{\mathrm{C}}$ materials could improve scalability and operating temperature, respectively. At the same time, fabrication of successful devices in wide wires and from higher-T$_{\mathrm{C}}$ materials like magnesium diboride has proven challenging. In this work, we compare helium ion irradiation in niobium nitride and magnesium diboride detectors with different material stacks in order to better understand the mechanics of irradiation and practical implications of encapsulating layers on effective dose. We examine the effects of experimental effective dose tests and compare these results to the damage per ion predicted by simulations in corresponding material stacks. In both materials, irradiation results in an increase in count rate, though for niobium nitride this increase has not fully saturated even at the highest tested dose of $2.6\times 10^{17}$ ions/cm$^{2}$, while for resist-encapsulated magnesium diboride even the lowest tested dose of $1\times 10^{15}$ ions/cm$^{2}$ appears higher than optimal. Our results demonstrate the general applicability of helium ion irradiation to vastly different devices and material stacks, albeit with differing optimal doses, and show the reproducibility and effectiveness of this post-processing technique in significantly improving SNSPD efficiency.
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| 3. |
- Boero, Riccardo, et al.
(författare)
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Pillars of Trust : An Experimental Study on Reputation and Its Effects
- 2009
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Ingår i: Sociological Research Online. - : SAGE Publications. - 1360-7804. ; 14:5, s. Article ID: 5-
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of laboratory experiments on the relevance of reputation for trust and cooperation in social interaction. We have extended a repeated investment game by adding new treatments where reputation is taken more explicitly into account than before. We then compared treatments where the investor and the trustee rate each other and treatments where the investor and the trustee were rated by a third party. The results showed that: (i) third party reputation positively affects cooperation by encapsulating trust; (ii) certain differences in the reputation mechanism can generate different cooperation outcomes. These results have interesting implications for the recent sociological debate on the normative pillars of markets.
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| 4. |
- Boero, Riccardo, et al.
(författare)
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Reputational cues in repeated trust games
- 2009
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Ingår i: The Journal of Socio-Economics. - : Elsevier BV. - 1053-5357 .- 1879-1239. ; 38:6, s. 871-877
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Tidskriftsartikel (refereegranskat)abstract
- The importance of reputation in human societies is highlighted both by theoretical models and empirical studies. In this paper, we have extended the scope of previous experimental studies based on trust games by creating treatments where players can rate their opponents’ behavior and know their past ratings. Our results showed that being rated by other players and letting this rating be known are factors that increase cooperation levels even when rational reputational investment motives are ruled out. More generally, subjects tended to respond to reputational opportunities even when this was neither rational nor explainable by reciprocity.
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| 5. |
- Boero, Riccardo, et al.
(författare)
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Why Bother with What Others Tell You? : An Experimental Data-Driven Agent-Based Model
- 2010
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Ingår i: JASSS. - 1460-7425. ; 13:3, s. Article ID: 6-
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the relevance of reputation to improve the explorative capabilities of agents in uncertain environments. We have presented a laboratory experiment where sixty-four subjects were asked to take iterated economic investment decisions. An agent-based model based on their behavioural patterns replicated the experiment exactly. Exploring this experimentally grounded model, we studied the effects of various reputational mechanisms on explorative capabilities at a systemic level. The results showed that reputation mechanisms increase the agents’ capability for coping with uncertain environments more than individualistic atomistic exploration strategies, although the former does entail a certain amount of false information inside the system.
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| 6. |
- Casnici, Niccolò, et al.
(författare)
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Cooperazione, fiducia e differenze digenere: un’indagine cross-metodologica
- 2012
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Ingår i: Rassegna italiana di sociologia. - : Societa Editrice Il Mulino. - 0486-0349. ; 53:4, s. 573-600
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates gender differences in cooperation and trust through a cross-methodological study that combined lab experiment and trust survey. First, we performed a repeated investment game played by 108 students, where a trust-based market interaction was modeled based on asymmetries of information. Results indicated that females were more trustworthy, being more sensitive to cooperation when being trusted by others, whereas males tended to take higher risk investment when trust was relatively more rewarding. A trust survey on a population of 488 students completed the experimental results by looking at general aspects of trust perception of subjects. Also empirical results confirmed significant gender differences in trust, being females more influenced by generalized trust and interpersonal obligations.
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| 7. |
- Castellani, Davide, et al.
(författare)
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Can European productivity make progress?
- 2018
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Ingår i: Intereconomics. - : Springer Science and Business Media LLC. - 0020-5346 .- 1613-964X. ; 53:2, s. 75-78
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Castellani, Davide, et al.
(författare)
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R&D and productivity in the US and the EU : Sectoral specificities and differences in the crisis
- 2019
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Ingår i: Technological Forecasting and Social Change. - : Elsevier BV. - 0040-1625. ; 138, s. 279-291
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Tidskriftsartikel (refereegranskat)abstract
- Using data on the US and EU top R&D spenders from 2004 until 2012, this paper investigates the sources of the US/EU productivity gap. We find robust evidence that US firms have a higher capacity to translate R&D into productivity gains (especially in the high-tech macro sector), and this contributes to explaining the higher productivity of US firms. Conversely, EU firms are more likely to achieve productivity gains through capital-embodied technological change, at least in the medium- and low-tech macro sectors. Our results also show that the US/EU productivity gap has worsened during the crisis period, as the EU companies have been more affected by the economic crisis in their capacity to translate R&D investments into productivity. Based on these findings, we make a case for a learning-based and selective R&D funding, which, instead of purely aiming at stimulating higher R&D expenditures, works on improving the firms’ capabilities to transform R&D into productivity gains.
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| 9. |
- Malbet, F., et al.
(författare)
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Faint objects in motion: the new frontier of high precision astrometry
- 2021
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Ingår i: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 51:3, s. 845-886
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Tidskriftsartikel (refereegranskat)abstract
- Sky survey telescopes and powerful targeted telescopes play complementary roles in astronomy. In order to investigate the nature and characteristics of the motions of very faint objects, a flexibly-pointed instrument capable of high astrometric accuracy is an ideal complement to current astrometric surveys and a unique tool for precision astrophysics. Such a space-based mission will push the frontier of precision astrometry from evidence of Earth-mass habitable worlds around the nearest stars, to distant Milky Way objects, and out to the Local Group of galaxies. As we enter the era of the James Webb Space Telescope and the new ground-based, adaptive-optics-enabled giant telescopes, by obtaining these high precision measurements on key objects that Gaia could not reach, a mission that focuses on high precision astrometry science can consolidate our theoretical understanding of the local Universe, enable extrapolation of physical processes to remote redshifts, and derive a much more consistent picture of cosmological evolution and the likely fate of our cosmos. Already several missions have been proposed to address the science case of faint objects in motion using high precision astrometry missions: NEAT proposed for the ESA M3 opportunity, micro-NEAT for the S1 opportunity, and Theia for the M4 and M5 opportunities. Additional new mission configurations adapted with technological innovations could be envisioned to pursue accurate measurements of these extremely small motions. The goal of this White Paper is to address the fundamental science questions that are at stake when we focus on the motions of faint sky objects and to briefly review instrumentation and mission profiles.
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| 10. |
- Prusti, T., et al.
(författare)
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The Gaia mission
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 595
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Tidskriftsartikel (refereegranskat)abstract
- Gaia is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page.
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| 11. |
- Takács, Károly, et al.
(författare)
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Employer Networks, Priming, and Discrimination in Hiring : An Experiment
- 2014
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Ingår i: Analytical Sociology. - Chichester, United Kingdom : John Wiley & Sons. - 9781119940388 ; , s. 373-396
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Bokkapitel (refereegranskat)abstract
- There is an ongoing debate on whether discrimination exists or not, and, if yes, in which forms. This chapter concentrates only on observed inequalities that are the direct consequences of hiring decisions. A variety of explanations have been provided to try to understand why discrimination tends to persist. A shift of focus toward psychological and structural mechanisms provides valuable insights for sociological investigations on labor market inequalities. The chapter focuses on two particular mechanisms. First, it analyzes whether priming individuals with a positive view on groups involved could decrease discriminatory bias. The second mechanism is more sociological and more in line with the idea of exploring social mechanisms which could increase or decrease discrimination. The chapter discusses certain findings that do not unequivocally support the statistical generalization of the hypothesized mechanisms, which is what one can expect generally in any empirical investigation of social mechanisms.
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| 12. |
- van Leeuwen, F., et al.
(författare)
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Gaia Data Release 1 : Open cluster astrometry: Performance, limitations, and future prospects
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 601
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Tidskriftsartikel (refereegranskat)abstract
- Context. The first Gaia Data Release contains the Tycho-Gaia Astrometric Solution (TGAS). This is a subset of about 2 million stars for which, besides the position and photometry, the proper motion and parallax are calculated using Hipparcos and Tycho-2 positions in 1991.25 as prior information. Aims. We investigate the scientific potential and limitations of the TGAS component by means of the astrometric data for open clusters. Methods. Mean cluster parallax and proper motion values are derived taking into account the error correlations within the astrometric solutions for individual stars, an estimate of the internal velocity dispersion in the cluster, and, where relevant, the effects of the depth of the cluster along the line of sight. Internal consistency of the TGAS data is assessed. Results. Values given for standard uncertainties are still inaccurate and may lead to unrealistic unit-weight standard deviations of least squares solutions for cluster parameters. Reconstructed mean cluster parallax and proper motion values are generally in very good agreement with earlier Hipparcos-based determination, although the Gaia mean parallax for the Pleiades is a significant exception. We have no current explanation for that discrepancy. Most clusters are observed to extend to nearly 15 pc from the cluster centre, and it will be up to future Gaia releases to establish whether those potential cluster-member stars are still dynamically bound to the clusters. Conclusions. The Gaia DR1 provides the means to examine open clusters far beyond their more easily visible cores, and can provide membership assessments based on proper motions and parallaxes. A combined HR diagram shows the same features as observed before using the Hipparcos data, with clearly increased luminosities for older A and F dwarfs.
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