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Three essays on auditing and corporate reporting
No full textThis doctoral thesis investigates the economic consequences of corporate disclosure and auditing within the context of emerging technological and sustainability challenges. Specifically, it addresses how corporate reporting and auditing adapt to meet the market and public demand for high-quality information. Spanning three distinct chapters, this research explores frontier areas where the accounting profession confronts issues that extend beyond traditional boundaries. Chapter 1 examines “Audit under the dark,” chapter 2 examines “cybersecurity commitment” through the lenses of disclosure, and chapter 3 examines audit firms’ “knowledge communication.” Each chapter leverages advanced data science methodologies to quantify and analyze these novel research concepts using unstructured and alternative data sources.
In Chapter 1, “Audit in the Dark: Auditor Response to Risk in the Absence of Authoritative Guidance” (co-authored with Beatriz García Osma, Thi Thuy Dung Nguyen, and W. Robert Knechel), we examine how auditors address risk in the absence of authoritative guidance, particularly, risks driven by cryptocurrency ecosystem of audit clients. We develop a novel measure of client-level cryptocurrency exposure from 10-K disclosures that captures the multifaceted aspects of cryptocurrency businesses and risks. We find that when audit firms provide their own timely guidance, they increase audit fees and critical audit matters while reducing going concern opinions. The later issuance of the SEC’s Staff Accounting Bulletin No. 121 reduced audit fees but didn’t eliminate the audit firm guidance premium. We also find evidence on audit firm staffing adjustments at the office level. Our study contributes novel evidence of how auditors proactively adapt to technological developments and emerging risks, providing insights into audit responses when facing new sources of uncertainty without established professional standards.
In Chapter 2, “Cybersecurity Commitment” (co-authored with Encarna Guillamon-Saorin), we propose a concept of the firm proactive strategy in the report and address cybersecurity risks as cybersecurity commitment. We then quantify cybersecurity commitment from the Management Discussion and Analysis (MD&A) section of 10-K filings and examine its relations with economic consequences and market valuation. We also decompose the nature of commitment by detecting five main topics: corporate governance, physical and financial resources, technology, policy, and stakeholder engagement. Our results indicate that companies showing cybersecurity commitment are less likely to experience data breaches, and this protective effect is particularly strong in companies with greater breach risks. Firms with
higher levels of cybersecurity commitment will get more favourable operating debt covenants. High-risk but non-breached firms benefit from showing a strong cybersecurity commitment, which lessens market negative spillover during breach events in the industry. Overall, our results suggest that cybersecurity commitment helps firms to lessen breaches and is valued positively by capital providers.
In Chapter 3, “Does Auditor Communication Matter? The Role of Knowledge Compatibility,” I examine auditor communication strategy and its relations with audit market dynamics and audit quality. This paper addresses a critical research question in the contemporary landscape of the audit profession, where auditors need to develop their expertise and maintain a profile as thought leaders due to the knowledge-intensive and credence nature of the audit. While prior literature has focused on traditional signals of expertise, such as industry portfolios, little is known about how auditors actively communicate their knowledge to market targets. To explore auditor communication strategy, I introduce a concept of knowledge compatibility, which is the alignment between the knowledge that auditors offer and that clients demand, and quantify it by similarities between audit firm podcasts and client forward-looking disclosure. I find that knowledge compatibility is positively associated with (i) audit fees for current clients, (ii) the likelihood of new auditor appointments, and (iii) accounting quality as evidenced by lower absolute discretionary accruals. These findings highlight the importance of auditor communication in addressing the idiosyncratic needs of audit clients with more favourable audit market outcomes. Collectively, the findings of this thesis contribute to the accounting literature and offer timely, empirical evidence to inform regulatory development and practical decision-making in complex, evolving domains. The novel research concepts, measurements, and methodologies developed herein, drawing upon accounting expertise, provide valuable tools for future research in accounting and other research disciplines.Programa de Doctorado en Empresa y Finanzas / Business and Finance por la Universidad Carlos III de MadridPresidente: Vedran Capkun.- Secretaria: Mónica López-Puertas Lamy.- Vocal: Belén Gill-De-Albornoz Nogue
Morphology of ejecta features from the impact on asteroid Dimorphos
No full textDocumento escrito por un elevado número de autores/as, solo se referencia el/la que aparece en primer lugar y los/as autores/as pertenecientes a la UC3MHypervelocity impacts play a significant role in the evolution of asteroids, causing material to be ejected and partially reaccreted. However, the dynamics and evolution of ejected material in a binary asteroid system have never been observed directly. Observations of Double Asteroid Redirection Test (DART) impact on asteroid Dimorphos have revealed features on a scale of thousands of kilometers, including curved ejecta streams and a tail bifurcation originating from the Didymos system. Here we show that these features result naturally from the dynamical interaction of the ejecta with the binary system and solar radiation pressure. These mechanisms may be used to constrain the orbit of a secondary body, or to investigate the binary nature of an asteroid. Also, they may reveal breakup or fission events in active asteroids, and help determine the asteroid’s properties following an impact event. In the case of DART, our findings suggest that Dimorphos is a very weak, rubble-pile asteroid, with an ejecta mass estimated to be in the range of (1.1-5.5)×107 kg.This work was supported by the DART mission, NASA Contract 80MSFC20D0004. F.F. acknowledges support from the European Union ERC Grant agreement No. 101077758 (TRACES). Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. F.F. acknowledges support from the Swiss National Science Foundation (SNSF) Ambizione grant No. 193346. J.-Y.L. acknowledges the support provided by NASA through grant HST-GO-16674 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract NAS 5-26555. The work of E.G.F. was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (#80NM0018D0004). S.D.R. and M.J. acknowledge support by the Swiss National Science Foundation (project number 200021 207359). S.S. acknowledges financial support from grant ref MR/W009498/1 of the UK Research and Innovation. P.M. acknowledges the French space agency CNES, ESA and The University of Tokyo. F.M. acknowledges financial support from grants PID2021-123370OB-I00 and CEX2021-001131-S funded by MCIN/AEI/10.13039/501100011033. G.T. acknowledges financial support from project FCE-1-2019-1-156451 of the Agencia Nacional de Investigacíon e Innovacíon ANII and Grupos I + D 2022 CSIC-Udelar (Uruguay). J.O. acknowledges support by grant PID2021-125883NB-C22 by the Spanish Ministry of Science and Innovation/State Agency of Research MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe”. J.O. and I.H. acknowledge support by the Spanish Research Council (CSIC) support for international cooperation: I-LINK project ILINK22061. O.K. acknowledges funding support from the PRODEX program managed by the European Space Agency (ESA) with help of the Belgian Science Policy Office (BELSPO). A.C.B. acknowledges funding by the NEO-MAPP project 717 GA 870377, EC H2020-SPACE-718 2018-2020/H2020-SPACE-2019, and by MICINN (Spain) PGC2021, PID2021-125883NB-C21. S.I., A.L., M.P., A.R. and F.T. acknowledge support by the Italian Space Agency (ASI) within the LICIACube project (ASI-INAF agreement n. 2019-31-HH.0) and HERA project (ASI-INAF agreement n. 2022−8-HH.0)
'A priori' shapley data value estimation
No full textDistributed machine learning approaches are required when training data cannot be collected in a central location, due to storage, transmission or privacy/security constraints. An important task in any distributed machine learning context, and Federated Learning is no exception, is data value estimation or credit allocation, where the goal is to reward each participant proportionally to their contribution to the final performance of the machine learning model. However, all existing data value estimation techniques require that training be completed before the data values are obtained, and in this sense they can be considered as 'a posteriori' approaches. Thus, all potential contributors must participate in the training process, regardless of the quality of their data or the final reward they can obtain. Here we present an 'a priori' Shapley data value estimation technique in which, based on some statistical measures provided by the participants, the central counterpart or aggregator can obtain reasonably accurate data value estimates before actually starting the distributed learning process. To the best of our knowledge, this is the first 'a priori' data value estimation approach proposed in the literature, and it can be used for the pre-selection of participants or to implement new pricing schemes. The introduced algorithms have been benchmarked using a variety of datasets and a logistic regression model, and we show that our 'a priori' estimates are very accurate, compared to the centralized Shapley data values.Acknowledgements This work was supported by the European Union’s Horizon-2020 RIA Programme (Musketeer project, grant number 824988) and by FEDER/Spanish Ministry of Economy and Business (grant number TEC2017-83838-R). Funding for APC: Universidad Carlos III de Madrid (Agreement CRUE-Madroño 2025). Funding Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by the European Union’s Horizon-2020 RIA Programme (Musketeer project, grant number 824988) and by FEDER/Spanish Ministry of Economy and Business (grant number TEC2017-83838-R). Funding for APC: Universidad Carlos III de Madrid (Agreement CRUE-Madroño 2025)
Gestión de vocabularios, interoperabilidad, inteligencia artificial y datos enlazados: el caso de los archivos de RTVE
No full textEsta tesis doctoral analiza el impacto de la inteligencia artificial (IA) en la gestión de archivos
audiovisuales, centrándose en su implementación en el Archivo de Radio Televisión Española
(RTVE). A través de tres artículos publicados, se examinan sus aplicaciones en la
automatización de los procesos de metadatado, la estandarización de vocabularios
controlados y la recuperación de información.
El objetivo principal de la investigación es demostrar cómo la IA puede mejorar el acceso a
los archivos audiovisuales en un medio de comunicación. Para ello, se analizan sus
beneficios, como la optimización de procesos, especialmente de generación automática de
metadatos así como los desafíos técnicos, organizativos y éticos que plantea su
implementación.
Los resultados destacan el papel transformador de la IA en la infraestructura tecnológica y los
procesos del Archivo RTVE, evidenciando su potencial para mejorar la eficiencia operativa y
fomentar la innovación. No obstante, se identifican limitaciones relacionadas con el
desempeño de los algoritmos, la necesidad de supervisión humana y la integración con los
procesos de trabajo actuales y la propia infraestructura tecnológica de la organización.
Las conclusiones subrayan la importancia de una estrategia clara para la adopción de la IA,
basada en la experimentación y la colaboración interdisciplinar. Asimismo, se destaca la
necesidad de garantizar que las soluciones desarrolladas sean explicables, controlables y
alineadas con los valores de la organización. Finalmente, se resalta el papel clave de la IA en
la evolución de los archivos audiovisuales, tanto en la mejora de procesos actuales como en
la exploración de nuevas oportunidades estratégicas.This doctoral thesis examines the impact of artificial intelligence (AI) on the management of audiovisual archives, focusing on its implementation in the Radio Televisión Española (RTVE) Archive. Through three published articles, it explores AI applications in the automation of metadata generation processes, the standardisation of controlled vocabularies, and information retrieval. The main goal of this research is to demonstrate how AI can enhance access to audiovisual archives in a media organisation. To this end, the study analyses its benefits, such as process optimisation—particularly in automatic metadata generation—as well as the technical, organisational, and ethical challenges associated with its implementation. The findings highlight the transformative role of AI in RTVE Archive’s technological infrastructure and processes, showcasing its potential to improve operational efficiency and drive innovation. However, certain limitations are identified, including algorithmic performance issues, the need for human oversight, and challenges in integrating AI with existing workflows and the organisation’s technological infrastructure. The conclusions emphasise the importance of a clear strategy for AI adoption, based on experimentation and interdisciplinary collaboration. Additionally, they stress the need to ensure that AI-driven solutions are explainable, controllable, and aligned with the organisation’s values. Finally, the research underscores AI’s key role in the evolution of audiovisual archives, both in improving current processes and in exploring new strategic opportunities.Programa de Doctorado en Documentación: Archivos y Bibliotecas en el Entorno Digital por la Universidad Carlos III de MadridPresidenta: Ana Reyes Pacios Lozano.- Secretario: Javier Guallar.- Vocal: Francesc Tarré
Proyecto PLEDs. Subproyecto PLEDs-CAP
No full textEl Proyecto Caracterización y Desarrollo de Aplicaciones Technologicas para LEDs de Perovskita de Haluro, PID2022-140090OB-C22, se centra en la caracterización de LEDs de perovskita de nueva generación, orientada a sus aplicaciones de carácter industrial.
Debido a sus excelentes propiedades, las perovskitas de haluros han revolucionado el campo de la optoelectrónica en la última década. Aunque esto se ha producido principalmente en células solares, sus posibilidades de adaptación de bandgap se unen a su baja recombinación radiativa para ofrecer una aplicación muy prometedora en diodos emisores de luz de perovskita (PeLED). El Proyecto PLED intentará dar un paso adelante hacia una nueva generación de PeLEDs, tratando de evitar dos de sus problemas fundamentales: el contenido de plomo y la inestabilidad a largo plazo.El Proyecto está financiado por el Ministerio de Ciencia e Innovación, la Agencia Estatal de Innovación: MCIN/AEI/ 10.13039/501100011033 y la Unión Europea a través de los fondos “FEDER, Una Manera de Hacer Europa”
A theoretical investigation of a magnetically shielded Hall thruster with conducting walls
No full textA first version of this work was presented at the 38th International Electric Propulsion ConferenceA 5 kW-class, magnetically shielded Hall effect thruster made of conducting walls is analyzed with a 2D particle/fluid model, in an attempt to understand the trends observed in recent prototypes. Two electrical configurations are considered: floating lateral walls and anode-tied lateral walls. The plasma response in both scenarios is compared with the baseline case of ceramic lateral walls. Under the same operating conditions and magnetic topology, there are minimal changes in performance and in most of the bulk plasma properties for the three cases. The main differences are observed in the electron current and energy flows to the walls in the anode-tied configuration, where the back wall receives only one fourth of the discharge current, and the energy deposition is more uniformly distributed along the walls, as compared with the other two cases, representing a potential advantage from the thermal management perspective. In a subsequent study on the anode-tied configuration, increasing the injected mass flow, up to a factor of four, reduces the energy losses per particle at the wall. At high mass flow operation, there is a large presence of doubly charged ions in the near plume, and the discharge power increases more than pro-portionally with the injected mass flow, but the thrust efficiency remains invariant.This work was supported by the project HEEP, funded by Agencia Estatal de Investigación (AEI), under Grant Agreement MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe,” under Grant Agreement PID2022-140035OB-I0
United States interests and Greenland's dilemmas
Full text link[ES] En diciembre de 2024, Donald Trump, sin haber llegado todavía a tomar posesión como presidente de Estados Unidos, manifestó su interés en comprar Groenlandia. Esta declaración ha generado una fuerte reacción al otro lado del océano Atlántico y ha recibido una clara negativa por parte de la primera ministra danesa y de otros dirigentes europeos. Groenlandia es una isla, la más grande del mundo, situada en el Ártico, está poblada mayoritariamente por indígenas inuit y se encuentra bajo control del reino de Dinamarca. Groenlandia, también, dispone de numerosos recursos, entre los que destacan las tierras raras, tan codiciadas por China, Estados Unidos o la Unión Europea, cruciales para la fabricación de baterías, aerogeneradores o paneles solares e indispensables en la transición energética. Además, Groenlandia es un punto crucial en la navegación de dos de las tres rutas árticas -el Paso del Noroeste y la todavía no practicable Ruta Transpolar-. A ello se suma su privilegiada situación estratégica en un Ártico profundamente tensionado tras el inicio de la agresión de la Federación Rusa sobre Ucrania. Es en este contexto en el que surge la iniciativa de Washington. Este trabajo analiza las diferentes aristas de la propuesta y sus razones, pero también los dilemas a los que se enfrenta la población groenlandesa, que ansía la independencia de Dinamarca en un contexto de extraordinaria complejidad.[EN] In December 2024, Donald Trump, without having yet taken office as President of the United States, expressed his interest in buying Greenland. This statement has generated a strong reaction on the other side of the Atlantic Ocean and has been clearly rejected by the Danish Prime Minister and other European leaders. Greenland is an island, the largest in the world, located in the Arctic, which is mostly populated by indigenous Inuit and belongs to the Kingdom of Denmark. Greenland also has numerous resources, including rare earth elements, which are highly coveted by China, the United States and the European Union, crucial for the manufacture of batteries, wind turbines and solar panels, and indispensable in the energy transition. Furthermore, Greenland is a crucial point in the navigation of two of the three Arctic routes -the Northwest Passage and the still impracticable Transpolar Route-. Added to this is its privileged strategic location in an Arctic that is deeply tense following the Russian Federation's aggression against Ukraine. It is in this context that Washington's initiative arises. This article analyses the different aspects of the proposal and the reasons behind it, but also the dilemmas faced by the Greenlandic population, which longs for independence from Denmark in an extraordinarily complex context.Este trabajo es resultado del Proyecto nacional de investigación "Vacíos normativos y desarrollo progresivo de la Agenda 2030. Especial relevancia para España" (PID2022-138339OB-I00) financiado por MICIU/AEI/10.13039/501100011033/FEDER/EU
Performance, Navigation and Control of a Spinning Electrodynamic Tether System
No full textProceedings of: 9th European Conference on Space Debris. Bonn (Germany).1-4 april 2025.As compared with electrodynamic tethers (EDTs) aligned with the local vertical, the performance of spinning EDTs depends weakly on the orbit inclination and are more favorable for deorbiting space debris at high-inclined orbits. This work studies the optimal orientation of the spin plane to maximize the deorbit performance. A semianalytical model for the decay rate, valid for circular orbits and based on a dipole model for the geomagnetic field, is presented and used to find a simple relation between the spin plane angle and the orbit inclination. Optimal values for the motional electric field and the decay rate as a function of the inclination are found, as well
as the control law for the electric current of the EDT. A good agreement is found between the results of the semianalytical model and BETsMA v2.0 simulations.This work was supported by the European Union’s Horizon Europe Research and Innovation Program (No. 101161603, E.T.COMPACT project)
Multi-Octave All-Dielectric Directional Coupler Using Integrated Half-Mirror for Ultrawideband Terahertz Systems
No full textNetwork analysis is foundational to calibrated instrumentation for practical handheld devices, and the directional coupler is the fundamental passive component that makes it possible. In this work, a terahertz-range handheld integrated-photonic directional coupler is reported with broad operation bandwidth spanning more than two octaves. The design adapts the underlying ray-tracing principles of classical parabolic reflectors and optical beam splitters to a monolithic substrateless micro-machined silicon structure. This advance holds the potential to unlock a new generation of terahertz systems, including vector network analyzers, that combine the broad bandwidth of bulky quasi-optical terahertz systems with the handheld form-factor and convenient, repeatable port access of guided-wave approaches.D. H. acknowledges support from the CONEX-Plus programme funded by Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant agreement No. 801538, and from an Australian Research Council Discover Early Career Researcher Award (Project No. DE240100625) funded by the Australian Government. This work was supported by the TERAmeasure project, funded by the Research Executive Agency (REA) under Grant Agreement No. 862788, and by the Smart Networks and Services Joint Undertaking (SNS JU) under the European Union's Horizon Europe research and innovation programme under Grant Agreement No. 101096949 (TERA6G project). This work was supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 287022738 – TRR 196 MARIE within project C09
A small-scale and autonomous testbed for three-line delta kites applied to airborne wind energy
No full textA mechanical control system and the guidance and control modules of a small-scale and autonomous testbed for three-line kites applied to airborne wind energy are presented. It extends the capabilities of a previously developed infrastructure by (i) changing the actuation system to add a third tether to control the kite pitch angle, (ii) adding running-line tensiometers to measure the three tether tensions while allowing tether reel-in and reel-out and onboard load cells to measure the bridle tensions, and (iii) providing a real-time control system to operate the kite autonomously in figure-eight trajectories. A controller based on a hybrid guidance scheme for figure-eight flight paths, which combines attractor points for the straight segments and a continuous heading angle tracking for the turns, was implemented and validated in an experimental campaign. Two flights of the campaign were used to illustrate the performance of the controller and its capability to adjust the lateral amplitude, elevation, and radius of the turns by varying a few parameters of the guidance module. The proposed control scheme was proven effective in achieving satisfactory and repeatable figure-eight paths. The experimental data collected during the autonomous flight were used to investigate the dynamics and control of the kite and the tethers. A correlation between the heading and roll angles of the kite was identified and modeled with a simple analytical law with empirical coefficients. Similarly to previous works on airborne wind energy, a linear relation between the derivative of the course angle and the steering input was found. The analysis of the on-ground tensiometers and the onboard load cells revealed a variable time delay of up to 0.2 s between both measurements. The work shows that the testbed and its instruments are suitable for investigating the effect of tether sagging and for developing and testing controllers for airborne wind energy systems.This research has been supported by Comunidad de Madrid (grant no. IND2022/AMB-23521) and MICIU/AEI/10.13039/501100011033 (grant no. PID2022-141520OB-I00)