512 research outputs found
Environmental ethics: values in and duties to the natural world (summarized with commentary by Panagiotis Perros)
No full textSummarized with commentary in Greek by Panagiotis Perros.Environmental ethics stands on a frontier, as radically theoretical as it is applied. Alone, it asks whether there can be nonhuman objects of duty. Animals, plants, endangered species, ecosystems, and even Earth are progressively unfamiliar as objects of duty, and puzzles arise both for theory and practice. Answers to such questions are as urgent as any humans face, and intimately related to the four principal issues on the world agenda: peace, population, development, and environment
Relativité générale et au-delà à travers le prisme des amplitudes de diffusion
No full textIn this thesis, we employ modern scattering amplitude techniques to discuss different aspects of effective field theories (EFTs) of gravity. The main focus is on scalar-tensor theories, a class of modified theories of gravity which introduce an additional massless scalar degree of freedom in addition to the graviton. Of particular interest are the scalar Gauss-Bonnet and Dynamical Chern-Simons models, which couple the scalar to the Gauss-Bonnet and Chern-Simons invariants, respectively. These models are both well motivated theoretically and of phenomenological interest since the first observation of gravitational waves by the LIGO/Virgo/KAGRA collaboration. By making use of recent advancements in the field of scattering amplitudes, it is possible to use Quantum Field Theory techniques to compute the dynamics of compact objects in classical gravitational scattering. The first part of the thesis reviews the recent advancements connecting gravitational observables to on-shell scattering amplitudes. The following part is dedicated to the study of gravitational waveforms from scattering of spinning compact objects in the aforementioned class of modified theories, employing on-shell amplitude methods and modern integration techniques to facilitate the calculations. We show how to derive explicit analytic results for the scalar and gravitational waveforms and the emitted power at leading order in the perturbative G expansion and up to linear order in spin. The computations are performed for both compact objects with vanishing scalar profiles and compact objects with scalar hair, providing a purely on-shell amplitude description for the latter. For hairy objects we also continue our results to the bound problem, making contact with the classical literature, finding perfect agreement for the case of compact objects with scalar monopole charges. Finally, we identify possible deformations from the conformal coupling that can contribute to radiation observables at low post-Newtonian orders. In the final chapter of the thesis, we explore possible UV completions of the scalar Gauss-Bonnet and Dynamical Chern-Simons effective theories. We assume heavy matter of spin S=0, 1/2, 1 coupled to the massless scalar at high energies, generating a three-point interaction. Then, the scalar couplings to Gauss-Bonnet and Chern-Simons can be generated through loops of the heavy matter and we compute the relation between the coupling and the Wilson coefficients explicitly through an EFT matching at one-loop. We show that the effective scalar coupling to the Gauss-Bonnet invariant is generically generated along with a number of shift-symmetric breaking interactions. On the other hand, we notice that for Dynamical Chern-Simons gravity there exists a unique shift-symmetric choice, corresponding to a theory of spin 1/2 fermions and a complex scalar with a Peccei-Quinn global symmetry. Throughout all the discussion we use on-shell amplitudes and unitarity methods to illuminate our results and streamline the computations.Dans cette thèse, nous utilisons des techniques modernes d'amplitudes de diffusion pour étudier différents aspects des théories effectives des champs (EFTs) en gravité. L'accent est mis sur les théories scalaire-tenseur, une classe de théories modifiées de la gravité qui introduisent un degré de liberté scalaire supplémentaire, sans masse, en plus du graviton. Parmi ces modèles, les théories scalaires de Gauss-Bonnet et de Chern-Simons dynamique sont particulièrement intéressantes, car elles couplent le champ scalaire aux invariants de Gauss-Bonnet et de Chern-Simons. Ces modèles sont à la fois bien motivés théoriquement et d'un grand intérêt phénoménologique depuis la première détection des ondes gravitationnelles par la collaboration LIGO/Virgo/KAGRA. Grâce aux avancées récentes dans le domaine des amplitudes de diffusion, il devient possible d'utiliser des techniques de théorie quantique des champs pour calculer la dynamique des objets compacts dans des processus de diffusion gravitationnelle classique. La première partie de la thèse passe en revue les progrès récents reliant les observables gravitationnelles aux amplitudes de diffusion «on-shell». La partie suivante est consacrée à l'étude des formes d'onde gravitationnelles issues de la diffusion d'objets compacts en rotation dans les théories modifiées mentionnées ci-dessus. Nous utilisons des méthodes d'amplitudes «on-shell» ainsi que des techniques d'intégration modernes afin de faciliter les calculs. Nous montrons comment obtenir des résultats analytiques explicites pour les formes d'onde scalaires et gravitationnelles, ainsi que pour la puissance rayonnée, à l'ordre dominant dans le développement perturbatif en G et jusqu'à l'ordre linéaire en spin. Les calculs sont effectués à la fois pour des objets compacts sans profil scalaire et pour des objets possédant un «cheveu scalaire», fournissant pour ces derniers une description entièrement fondée sur les amplitudes «on-shell». Dans le cas des objets «chevelus», nous poursuivons également les résultats dans le régime des états liés, en les comparant à la littérature classique, et trouvons un accord parfait dans le cas d'objets compacts dotés de charges scalaires monopoles. Enfin, nous identifions les déformations possibles du couplage conforme qui peuvent contribuer aux observables radiatives aux ordres post-newtoniens bas. Dans le dernier chapitre de la thèse, nous explorons des complétions ultraviolettes possibles des théories effectives scalaires de Gauss-Bonnet et de Chern-Simons dynamique. Nous supposons l'existence de matière lourde de spin S=0,1/2,1 couplée au scalaire sans masse à haute énergie, générant une interaction à trois points. Les couplages scalaires aux invariants de Gauss-Bonnet et de Chern-Simons peuvent alors être engendrés par des boucles de cette matière lourde, et nous calculons explicitement la relation entre ces couplages et les coefficients de Wilson à l'aide d'un appariement EFT à une boucle. Nous montrons que le couplage effectif du scalaire à l'invariant de Gauss-Bonnet est, de manière générale, accompagné d'un certain nombre d'interactions qui brisent la symétrie de décalage. En revanche, nous remarquons que, pour la gravité de Chern-Simons dynamique, il existe un choix unique respectant la symétrie de décalage, correspondant à une théorie comportant des fermions de spin 1/2 et un scalaire complexe possédant une symétrie globale de Peccei-Quinn. Tout au long de cette étude, nous utilisons les amplitudes «on-shell» et les méthodes d'unitarité afin d'éclairer nos résultats et de simplifier les calculs
Relativité générale et au-delà à travers le prisme des amplitudes de diffusion
No full textIn this thesis, we employ modern scattering amplitude techniques to discuss different aspects of effective field theories (EFTs) of gravity. The main focus is on scalar-tensor theories, a class of modified theories of gravity which introduce an additional massless scalar degree of freedom in addition to the graviton. Of particular interest are the scalar Gauss-Bonnet and Dynamical Chern-Simons models, which couple the scalar to the Gauss-Bonnet and Chern-Simons invariants, respectively. These models are both well motivated theoretically and of phenomenological interest since the first observation of gravitational waves by the LIGO/Virgo/KAGRA collaboration. By making use of recent advancements in the field of scattering amplitudes, it is possible to use Quantum Field Theory techniques to compute the dynamics of compact objects in classical gravitational scattering. The first part of the thesis reviews the recent advancements connecting gravitational observables to on-shell scattering amplitudes. The following part is dedicated to the study of gravitational waveforms from scattering of spinning compact objects in the aforementioned class of modified theories, employing on-shell amplitude methods and modern integration techniques to facilitate the calculations. We show how to derive explicit analytic results for the scalar and gravitational waveforms and the emitted power at leading order in the perturbative G expansion and up to linear order in spin. The computations are performed for both compact objects with vanishing scalar profiles and compact objects with scalar hair, providing a purely on-shell amplitude description for the latter. For hairy objects we also continue our results to the bound problem, making contact with the classical literature, finding perfect agreement for the case of compact objects with scalar monopole charges. Finally, we identify possible deformations from the conformal coupling that can contribute to radiation observables at low post-Newtonian orders. In the final chapter of the thesis, we explore possible UV completions of the scalar Gauss-Bonnet and Dynamical Chern-Simons effective theories. We assume heavy matter of spin S=0, 1/2, 1 coupled to the massless scalar at high energies, generating a three-point interaction. Then, the scalar couplings to Gauss-Bonnet and Chern-Simons can be generated through loops of the heavy matter and we compute the relation between the coupling and the Wilson coefficients explicitly through an EFT matching at one-loop. We show that the effective scalar coupling to the Gauss-Bonnet invariant is generically generated along with a number of shift-symmetric breaking interactions. On the other hand, we notice that for Dynamical Chern-Simons gravity there exists a unique shift-symmetric choice, corresponding to a theory of spin 1/2 fermions and a complex scalar with a Peccei-Quinn global symmetry. Throughout all the discussion we use on-shell amplitudes and unitarity methods to illuminate our results and streamline the computations.Dans cette thèse, nous utilisons des techniques modernes d'amplitudes de diffusion pour étudier différents aspects des théories effectives des champs (EFTs) en gravité. L'accent est mis sur les théories scalaire-tenseur, une classe de théories modifiées de la gravité qui introduisent un degré de liberté scalaire supplémentaire, sans masse, en plus du graviton. Parmi ces modèles, les théories scalaires de Gauss-Bonnet et de Chern-Simons dynamique sont particulièrement intéressantes, car elles couplent le champ scalaire aux invariants de Gauss-Bonnet et de Chern-Simons. Ces modèles sont à la fois bien motivés théoriquement et d'un grand intérêt phénoménologique depuis la première détection des ondes gravitationnelles par la collaboration LIGO/Virgo/KAGRA. Grâce aux avancées récentes dans le domaine des amplitudes de diffusion, il devient possible d'utiliser des techniques de théorie quantique des champs pour calculer la dynamique des objets compacts dans des processus de diffusion gravitationnelle classique. La première partie de la thèse passe en revue les progrès récents reliant les observables gravitationnelles aux amplitudes de diffusion «on-shell». La partie suivante est consacrée à l'étude des formes d'onde gravitationnelles issues de la diffusion d'objets compacts en rotation dans les théories modifiées mentionnées ci-dessus. Nous utilisons des méthodes d'amplitudes «on-shell» ainsi que des techniques d'intégration modernes afin de faciliter les calculs. Nous montrons comment obtenir des résultats analytiques explicites pour les formes d'onde scalaires et gravitationnelles, ainsi que pour la puissance rayonnée, à l'ordre dominant dans le développement perturbatif en G et jusqu'à l'ordre linéaire en spin. Les calculs sont effectués à la fois pour des objets compacts sans profil scalaire et pour des objets possédant un «cheveu scalaire», fournissant pour ces derniers une description entièrement fondée sur les amplitudes «on-shell». Dans le cas des objets «chevelus», nous poursuivons également les résultats dans le régime des états liés, en les comparant à la littérature classique, et trouvons un accord parfait dans le cas d'objets compacts dotés de charges scalaires monopoles. Enfin, nous identifions les déformations possibles du couplage conforme qui peuvent contribuer aux observables radiatives aux ordres post-newtoniens bas. Dans le dernier chapitre de la thèse, nous explorons des complétions ultraviolettes possibles des théories effectives scalaires de Gauss-Bonnet et de Chern-Simons dynamique. Nous supposons l'existence de matière lourde de spin S=0,1/2,1 couplée au scalaire sans masse à haute énergie, générant une interaction à trois points. Les couplages scalaires aux invariants de Gauss-Bonnet et de Chern-Simons peuvent alors être engendrés par des boucles de cette matière lourde, et nous calculons explicitement la relation entre ces couplages et les coefficients de Wilson à l'aide d'un appariement EFT à une boucle. Nous montrons que le couplage effectif du scalaire à l'invariant de Gauss-Bonnet est, de manière générale, accompagné d'un certain nombre d'interactions qui brisent la symétrie de décalage. En revanche, nous remarquons que, pour la gravité de Chern-Simons dynamique, il existe un choix unique respectant la symétrie de décalage, correspondant à une théorie comportant des fermions de spin 1/2 et un scalaire complexe possédant une symétrie globale de Peccei-Quinn. Tout au long de cette étude, nous utilisons les amplitudes «on-shell» et les méthodes d'unitarité afin d'éclairer nos résultats et de simplifier les calculs
R-CAUSTIC: Rippling CAUSTICs underwater Image dataset
No full text<p><strong>Description</strong></p><p>Rippling caustics seem to be the main factor degrading the underwater RGB image quality and affecting the image- based 3D reconstruction process in very shallow waters. These effects are adversely affecting image matching algorithms by throwing off most of them, leading to less accurate matches and causing issues in the Simultaneous Localization and Mapping (SLAM) based navigation of the Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUV) on shallow waters. Also, they are the main cause for dissimilarities in the generated textures and orthoimages. In order to fill the gap in the literature regading underwater rippling caustics imagery with real ground truth and reference images, the first real-world underwater caustics benchmark dataset which contains 1465 underwater images is presented. Together with the RGB imagery, the corresponding generated ground truth images are delivered for facilitating the training and testing of machine learning and deep learning methods for image classification. R-CAUSTIC dataset also provides the necessary data to evaluate, at least to some extent, the performance of 3D reconstruction approaches. Data were acquired using a GoPro Hero 4 Black action camera with image dimensions of 4000 x 3000 pixels, focal length of 2.77mm and pixel size of 1.55μm and a tripod. Action cameras are widely used for underwater image acquisition. The dataset was captured in near-shore underwater sites at depths varying from 0.5 to 2m. No artificial light sources were used. Due to the wind, the turbulent surface of the water created dynamic rippling caustics on the seabed. In total 1465 RGB images were collected, separated in 7 different datasets; five of them containing stereo images, one of them tri-stereo images and one consists of multi-stereo imagery acquired in 7 different camera poses.</p><p> </p><p><strong>Publication</strong></p><p>The paper is availbale in Open Access here: https://ieeexplore.ieee.org/document/10172291</p><p><strong>If you use this dataset please cite it as R-CAUSTIC</strong> [Reference].<br>[Reference]: <strong>P. Agrafiotis, K. Karantzalos and A. Georgopoulos, "Seafloor-Invariant Caustics Removal From Underwater Imagery," in </strong><i><strong>IEEE Journal of Oceanic Engineering</strong></i><strong>, vol. 48, no. 4, pp. 1300-1321, Oct. 2023, doi: 10.1109/JOE.2023.3277168.</strong></p><p>BibTeX:</p><p>@ARTICLE{10172291,
author={Agrafiotis, Panagiotis and Karantzalos, Konstantinos and Georgopoulos, Andreas},
journal={IEEE Journal of Oceanic Engineering},
title={Seafloor-Invariant Caustics Removal From Underwater Imagery},
year={2023},
volume={48},
number={4},
pages={1300-1321},
doi={10.1109/JOE.2023.3277168}}</p><p> </p>
R-CAUSTIC: Rippling CAUSTICs underwater Image dataset
No full text<p> </p>
<h3><strong>Version 2 available! Please make sure to download the latest version of the dataset! <br></strong></h3>
<p> </p>
<p><strong>Description</strong></p>
<p>Rippling caustics seem to be the main factor degrading the underwater RGB image quality and affecting the image- based 3D reconstruction process in very shallow waters. These effects are adversely affecting image matching algorithms by throwing off most of them, leading to less accurate matches and causing issues in the Simultaneous Localization and Mapping (SLAM) based navigation of the Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUV) on shallow waters. Also, they are the main cause for dissimilarities in the generated textures and orthoimages. In order to fill the gap in the literature regading underwater rippling caustics imagery with real ground truth and reference images, the first real-world underwater caustics benchmark dataset which contains 1465 underwater images is presented. Together with the RGB imagery, the corresponding generated ground truth images are delivered for facilitating the training and testing of machine learning and deep learning methods for image classification. R-CAUSTIC dataset also provides the necessary data to evaluate, at least to some extent, the performance of 3D reconstruction approaches. Data were acquired using a GoPro Hero 4 Black action camera with image dimensions of 4000 x 3000 pixels, focal length of 2.77mm and pixel size of 1.55μm and a tripod. Action cameras are widely used for underwater image acquisition. The dataset was captured in near-shore underwater sites at depths varying from 0.5 to 2m. No artificial light sources were used. Due to the wind, the turbulent surface of the water created dynamic rippling caustics on the seabed. In total 1465 RGB images were collected, separated in 7 different datasets; five of them containing stereo images, one of them tri-stereo images and one consists of multi-stereo imagery acquired in 7 different camera poses.</p>
<p> </p>
<p><strong>Publication</strong></p>
<p>The paper is availbale in Open Access here: https://ieeexplore.ieee.org/document/10172291</p>
<p><strong>If you use this dataset please cite it as R-CAUSTIC</strong> [Reference].<br>[Reference]: <strong>P. Agrafiotis, K. Karantzalos and A. Georgopoulos, "Seafloor-Invariant Caustics Removal From Underwater Imagery," in </strong><em><strong>IEEE Journal of Oceanic Engineering</strong></em><strong>, vol. 48, no. 4, pp. 1300-1321, Oct. 2023, doi: 10.1109/JOE.2023.3277168.</strong></p>
<p>BibTeX:</p>
<p>@ARTICLE{10172291, author={Agrafiotis, Panagiotis and Karantzalos, Konstantinos and Georgopoulos, Andreas}, journal={IEEE Journal of Oceanic Engineering}, title={Seafloor-Invariant Caustics Removal From Underwater Imagery}, year={2023}, volume={48}, number={4}, pages={1300-1321}, doi={10.1109/JOE.2023.3277168}}</p>
<p> </p>
Does genetic diversity on corporate boards lead to improved environmental performance?
No full textElsevier
Journal of International Financial Markets, Institutions and Money
Volume 84, April 2023, 101756
Journal of International Financial Markets, Institutions and Money
Does genetic diversity on corporate boards lead to improved environmental performance?
Author links open overlay panelRenatas Kizys a, Emmanuel C. Mamatzakis b, Panagiotis Tzouvanas c
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https://doi.org/10.1016/j.intfin.2023.101756
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Highlights
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We examine the effect of boards’ genetic diversity (GENETICD) on corporate ESG performance.
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ESG performance and disclosures are higher in more genetically diverse firms.
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The positive GENETICD effect on ESG performance is driven by the environmental pillar.
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Corporate carbon performance significantly improves with increases in GENETICD.
We study the effects of boards’ genetic diversity on corporate environmental performance. Using a multidimensional information set for 3690 US firms during the period from 2005 to 2019, and three different measures of genetic diversity, we find that, pursuant to the diversity theory, which posits that diversity improves the quality of management decisions and business ethics, genetic diversity leads to improved environmental performance. We also find that genetic diversity improves carbon and governance performance, and ESG disclosure. Particularly, a one percentage point increase in boards’ genetic diversity will increase the carbon performance, measured by the inverse of the carbon emissions to total assets ratio, and environmental performance by 3.54% and 5.57%, respectively. Our results remain robust to different model specifications, while also controlling for endogeneity. In terms of policy implications, results suggest that the key to tackling climate challenges is to promote boards’ genetic diversity
On-shell approach to scalar hair in spinning binaries
No full textInternational audienceWe propose an on-shell description of spinning binary systems in gravitational theories where compact objects display scalar hair. The framework involves matter particles of arbitrary spin which, in addition to the minimal coupling to gravitons, are conformally coupled to a massless scalar mediating non-standard interactions. We use the unitary factorization techniques to derive the on-shell amplitudes relevant for emission of scalars and gravitons in matter scattering, paying attention to parametrize the freedom due to contact terms. Using the KMOC formalism, these amplitudes allow one to derive succinct expressions for the radiation waveforms at the leading post-Minkowskian order, together with the associated memory effects. Furthermore, we compute the power emitted via gravitational and scalar radiation in hyperbolic encounters of compact objects. After a continuation to bound orbits, these can be compared with the results obtained in specific scalar-tensor theories where black holes exhibit scalar hair, such as the scalar-Gauss-Bonnet or dynamical Chern-Simons theories. Finally, we identify possible deformations from the conformal coupling that can contribute to radiation observables at the same post-Newtonian order
Dataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment'
No full textDataset in support of the Southampton doctoral thesis 'The boatbuilding tradition of the Aegean during the Late Neolithic – Early Bronze Age periods. Typological classification, digital reconstruction and seakeeping assessment' Appendix D - Resistance data and Appendix C - Stability data.
This dataset is focused on two appendices:
Appendix D - Resistance data. D.1 Resistance data produced by the author via MAXSURF Resistance for this thesis.
Appendix C - Stability data
C1. Stability data – STIX and ISO criteria, produced by the author via MAXSURF Stability software for his thesis
This research was funded by Southampton Marine and Maritime Institute (SMMI), Vice-Chancellor's Scholarship, Greek Archaeological Committee UK (GACUK)
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Spinning waveforms of scalar radiation in quadratic modified gravity
No full textInternational audienceWe study scalar-tensor gravitational theories using on-shell amplitude methods. We focus on theories with gravity coupled to a massless scalar via the Gauss-Bonnet and Chern-Simons terms. In this framework, we calculate the waveforms for classical scalar radiation emitted in scattering of macroscopic objects, including spin effects. To this end, we use the Kosower-Maybee-O'Connell formalism, with the 5-particle amplitude for scalar emission in matter scattering calculated at tree level using the unitarity-factorization bootstrap techniques. We also discuss in detail the dependence of that amplitude on the contact terms of the intermediate 4-particle scalar-graviton-matter amplitude. Finally, we discuss the conditions for resolvability of classical scalar radiation
Ideas in trenches: Power and polemics in Panagiotis Kondylis
No full textThe author of the article attempts to examine the positions of Panagiotis Kondylis on the intellectual history and ideas’ polemical nature that is the basic feature for understanding the configuration and development of an idea-theory in history. In order to achieve a full understanding of the specific concept of the intellectual history, first of all we have to analyze the Greek thinker's positions on the power and the way in which the search for power as a basic and irrevocable anthropological condition leads to a polemic condition within the social field. This polemic condition is also evident in the field of ideas, as ideas can be seen as the attempt to form worldviews by the respective subject or group of subjects that have the purpose of self-preservation and expanding their power. Therefore, in this article the emphasis is placed on two different areas of Kondylis' thought, the philosophy of man and then on the description of the ideas’ formulation. 
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