| 1. |
- Abend, Sven, et al.
(författare)
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Terrestrial very-long-baseline atom interferometry : Workshop summary
- 2024
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Ingår i: AVS Quantum Science. - : American Institute of Physics (AIP). - 2639-0213. ; 6:2
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Forskningsöversikt (refereegranskat)abstract
- This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more kilometer--scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions.
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| 2. |
- Brill, Markus, et al.
(författare)
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Phragmen's Voting Methods and Justified Representation
- 2017
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Ingår i: Thirty-First AAAI Conference On Artificial Intelligence. - : Assoc Advancement Artificial Intelligence. ; , s. 406-413
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Konferensbidrag (refereegranskat)abstract
- In the late 19th century, Lars Edvard Phragmen proposed a load-balancing approach for selecting committees based on approval ballots. We consider three committee voting rules resulting from this approach: two optimization variants-one minimizing the maximal load and one minimizing the variance of loads-and a sequential variant. We study Phragmen's methods from an axiomatic point of view, focussing on justified representation and related properties that have recently been introduced by Aziz et al. (2015a) and Sanchez-Fernandez et al. (2017). We show that the sequential variant satisfies proportional justified representation, making it the first known polynomial-time computable method with this property. Moreover, we show that the optimization variants satisfy perfect representation. We also analyze the computational complexity of Phragmen's methods and provide mixed- integer programming based algorithms for computing them.
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| 3. |
- Brill, Markus, et al.
(författare)
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Phragmén's voting methods and justified representation
- 2024
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Ingår i: Mathematical programming. - : Springer. - 0025-5610 .- 1436-4646. ; 203:1-2, s. 47-76
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Tidskriftsartikel (refereegranskat)abstract
- In the late 19th century, Swedish mathematician Edvard Phragmén proposed a load-balancing approach for selecting committees based on approval ballots. We consider three committee voting rules resulting from this approach: two optimization variants—one minimizing the maximum load and one minimizing the variance of loads—and a sequential variant. We study Phragmén's methods from an axiomatic point of view, focusing on properties capturing proportional representation. We show that the sequential variant satisfies proportional justified representation, which is a rare property for committee monotonic methods. Moreover, we show that the optimization variants satisfy perfect representation. We also analyze the computational complexity of Phragmén's methods and provide mixed-integer programming based algorithms for computing them.
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| 4. |
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| 5. |
- Janson, Svante, et al.
(författare)
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Generalized Stirling permutations, families of increasing trees and urn models
- 2011
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Ingår i: Journal of combinatorial theory. Series A (Print). - : Elsevier BV. - 0097-3165 .- 1096-0899. ; 118:1, s. 94-114
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Tidskriftsartikel (refereegranskat)abstract
- Bona (2007) [6] studied the distribution of ascents plateaux and descents in the class of Stirling permutations, introduced by Gessel and Stanley (1978) [13] Recently Janson (2008) [17] showed the connection between Stirling permutations and plane recursive trees and proved a joint normal law for the parameters considered by Bona Here we will consider generalized Stirling permutations extending the earlier results of Bona (2007) [6] and Janson (2008) [17] and relate them with certain families of generalized plane recursive trees and also (k + 1)-ary increasing trees We also give two different bijections between certain families of increasing trees which both give as a special case a bijection between ternary increasing trees and plane recursive trees In order to describe the (asymptotic) behaviour of the parameters of interests we study three (generalized) Polya urn models using various methods.
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| 6. |
- Zackrisson, Erik, et al.
(författare)
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Terrestrial Planets Across Space And Time
- 2016
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Ingår i: ASTROPHYSICAL JOURNAL. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 833:2
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Tidskriftsartikel (refereegranskat)abstract
- The study of cosmology, galaxy formation, and exoplanets has now advanced to a stage where a cosmic inventory of terrestrial planets (TPs) may be attempted. By coupling semianalytic models of galaxy formation to a recipe that relates the occurrence of planets to the mass and metallicity of their host stars, we trace the population of TPs around both solar-mass (FGK type) and lower-mass (M dwarf) stars throughout all of cosmic history. We find that the mean age of TPs in the local universe is 7 +/- 1 Gyr for FGK hosts and 8 +/- 1 Gyr for M dwarfs. We estimate that hot Jupiters have depleted the population of TPs around FGK stars by no more than approximate to 10%, and that only approximate to 10% of the TPs at the current epoch are orbiting stars in a metallicity range for which such planets have yet to be confirmed. The typical TP in the local universe is located in a spheroid-dominated galaxy with a total stellar mass comparable to that of the Milky Way. When looking at the inventory of planets throughout the whole observable universe, we argue for a total of approximate to 1 x 10(19) and approximate to 5 x 10(20) TPs around FGK and M stars, respectively. Due to light travel time effects, the TPs on our past light cone exhibit a mean age of just 1.7 +/- 0.2 Gyr. These results are discussed in the context of cosmic habitability, the Copernican principle, and searches for extraterrestrial intelligence at cosmological distances.
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