Donostia International Physics Center
Archivo Digital para la Docencia y la InvestigaciónNot a member yet
46642 research outputs found
Sort by
Reflexiones a propósito de los falsos autónomos
No full text[ES] Este Trabajo de Fin de Grado analiza la figura del falso autónomo, una realidad laboral que, pese a su creciente visibilidad en ámbitos como el de las plataformas digitales, está presente en múltiples sectores y profesiones. El estudio parte de una revisión de las diferentes formas de relación contractual reconocidas tanto por el Derecho de la Unión Europea como por el ordenamiento jurídico español, y se enfoca en los elementos que permiten identificar cuándo una relación aparentemente autónoma está encubriendo, en realidad, un vínculo laboral por cuenta ajena.
Se abordan los motivos que llevan a las empresas a recurrir a la contratación de esta figura, así como las responsabilidades que esto puede acarrear. Además, se analiza la presencia de falsos autónomos en distintos ámbitos laborales, prestando especial atención al fenómeno de la economía colaborativa y al contexto normativo que dio origen a la Ley Rider.
Finalmente, el presente trabajo ofrece una reflexión crítica sobre la capacidad del Derecho del Trabajo para afrontar estas nuevas formas de precarización laboral y, en esa línea, plantea posibles soluciones que permitan responder con mayor eficacia a los retos que presenta el empleo en el siglo XXI.[EN] This Final Degree Project analyses the figure of the false self-employed, a labour reality that, despite it ́s growing visibility in areas such as digital platforms, is present across a wide range of sectors and professions. The study begins with a review of the different forms of contractual relationships recognised by European Union law and by the Spanish legal system, focusing on the key elements that allow us to identify when an apparently self-employed contractual relationship is actually concealing an employment relationship.
It examines the reasons why companies turn to this form of hiring, as well as the legal
responsibilities that may arise. Furthermore, the presence of false self-employment is
analysed across different sectors, with particular attention to the phenomenon of the sharing economy and the regulatory context that gave rise to the so-called “Rider Law”.
Finally, this paper offers a critical reflection on the capacity of labour law to deal with these
new forms of employment precariousness and, in this regard, proposes possible solutions to more effectively respond to the challenges posed by 21st century employment
Joint modeling with beta-binomial distribution for patient- reported outcomes and survival data
No full text199 p.This thesis addresses critical methodological gaps in the joint analysis of patient-reported outcomes (PROs) and survival data. PROs, as discrete bounded measures with inherent overdispersion, require specialized statistical treatment that conventional Gaussian-based joint models fail to provide. We develop novel methodological frameworks that properly account for PRO characteristics through beta-binomial distributions, overcoming limitations of existing approaches.In this work, we propose, explore, and discuss various statistical approaches for joint modeling, from frequentist to bayesian proposals. Our work highlights the advantages of joint models that integrate longitudinal and survival data while emphasizing the importance of choosing appropriate distributions for PRO data.In particular, in this dissertation, we propose three joint models to analyze both, the longitudinal PRO and survival data: a) A frequentist two-stage approach, providing initial practical solutions. In this proposal, the central innovation lies in a joint model based on a two-stage methodology that incorporates the beta-binomial distribution for the longitudinal submodel. This methodology avoids computational complexities while ensuring a distributional fit that considers the natural characteristics of PRO (discrete, bounded and overdispersed).b) A Bayesian one-stage joint model, offering improved estimation. In this proposal, the main objective was to keep the distributional features for PRO data regarding beta-binomial distribution while performing a joint specification approach. The Bayesian formulation of the problem allows us to avoid the computational complexities we found in frequentist approaches. Moreover, we considered the parameters¿ posterior estimations to perform dynamic predictions of the survival probabilities, being updated as more longitudinal PRO information is considered. c) A multivariate Bayesian framework, enabling simultaneous analysis of multiple PRO dimensions with survival outcomes. In this proposal, our primary objective was to address the multidimensional structure of questionnaires within the joint modeling framework. However, when dealing with multivariate approaches, it might be necessary to use regularization techniques to avoid possible multicollinearity. Therefore, we explored common regularization techniques in the literature within the joint modeling framework.The proposed methods' performance is evaluated using simulation studies, and comparisons with common approaches in the literature are provided. Additionally, we applied these methods to analyze a study carried out with chronic obstructive pulmonary disease (COPD) patients, where longitudinal tendencies for PRO data collected and their relationship with patients¿ mortality are of interes
Macroeconomic and environmental impacts of two decarbonization options for the Dutch steel industry: green relocation versus green hydrogen imports
No full textDecarbonizing the steel industry will require a shift towards renewable energy. However, costs and emissions associated with the long-distance transport of renewable energy carriers may incentivize the relocation of steel production closer to renewable energy sources. This “green relocation” would affect regional economic structures and global trade patterns. Nevertheless, the macroeconomic and environmental impacts of alternative industry location options remain underexplored. This study compares the impacts on value-added, prices, and emissions under two options for decarbonizing the Dutch steel industry: importing green hydrogen from Brazil to produce green steel in the Netherlands versus relocating production to Brazil and transporting green steel to the Netherlands. Impacts are analyzed by combining a price and a quantity model within an environmentally extended multiregional input-output (EE-MRIO) framework. Results suggest that the relocation option brings the greatest synergies between climate and economic goals at the global level, as it leads to lower production costs, smaller price effects, and greater emissions reductions. However, relocation also results in stronger distributive impacts across global regions. Higher carbon prices would be insufficient to counteract relocation incentives. This calls for policymakers in industrialized countries to systematically consider the possibility of green relocation when designing decarbonization and industrial competitiveness strategies.The authors would like to thank Henri de Groot for his comments on a previous version of this work
Towards scalable semi-supervised learning on graphs
No full text134 p.Graph-based semi-supervised learning (GSSL) has attracted considerable attentiondue to its ability to leverage both labeled and unlabeled data to improveclassification performance. This thesis addresses the limitations of traditional GSSLmethods, such as reliance on predefined graphs, computational inefficiency withlarge datasets, treating data equally, and insufficient handling of unlabeled data, byproposing a unified and scalable framework.Recent advancements in GSSL have primarily focused on predefined graphstructures, which often do not accurately represent the data topology, and strugglewith scalability issues. To overcome these challenges, this research introducesseveral innovative approaches, including anchor-based graph construction, adaptivesample weighting, and dynamic self-training, specifically designed for large-scaledatasets.The Joint Graph and Reduced Flexible Manifold Embedding (SGRFME) algorithmintegrates anchor graph computation into the learning model. This approach notonly scales efficiently to large databases but also improves the accuracy of labelpredictions for test samples through linear transformations. Experimental results ondatasets such as NORB, RCV1, and Covtype demonstrate the method'seffectiveness and scalability.Addressing graph topology imbalance, the Weighted Simultaneous GraphConstruction and Reduced Flexible Manifold Embedding (W-SGRFME) algorithmextends the concept of graph topology imbalance to large datasets and incorporatescomputed weights of labeled samples into the model. The fusion of labels andfeatures of anchors allows for adaptive graph construction, resulting in superiorperformance on large datasets.A scalable and inductive semi-supervised classifier with sample weighting based ongraph topology, called the Weighted Joint Graph Construction and ReducedFlexible Manifold Embedding (W-JGRFME), employs calculated weights oflabeled samples for label-matching, leading to a unified and scalable model thatsimultaneously labels unlabeled data and constructs an adaptive anchor graph.Experimental results on extensive datasets, including MNIST, validate the method'srobustness and superiority.A unified framework for inductive and scalable GSSL using adaptive sampleweighting, termed Adaptive Weighted Simultaneous Graph Construction andReduced Flexible Manifold Embedding (AW-SGRFME), assigns adaptive weightsto labeled samples based on their estimated labels and constructs an anchor-toanchoraffinity graph by incorporating both feature and label information. Theefficacy of this method is illustrated through experiments on large-scale datasets.Lastly, the Self-training Simultaneous Graph Construction and Reduced FlexibleManifold Embedding (SSGRFME) framework, tailored for very large datasets,utilizes pseudo-labeling to enhance the model's accuracy by incorporatingconfidently predicted labels of random batches of unlabeled samples into thetraining set. The anchor-to-anchor affinity graphs facilitate robust learning, asdemonstrated by comprehensive experimentation across diverse large datasets.Overall, this thesis makes significant contributions to the field of GSSL byintroducing automatic graph consrtuction, weighted labeled samples, and selftrainingmethods that effectively address the challenges of large-scale semisupervisedlearning. These innovative approaches not only enhance the performanceof GSSL models but also extend their applicability across various domains, providinga robust foundation for future research. The main contributions of the thesis areoutlined below.(1) Proposes the SGRFME model, which handles large-scale datasets using anchorpoints. SGRFME jointly predicts labels, constructs the anchor affinity matrix, andestimates a projection matrix for test samples.(2) SGRFME emphasizes the integration of graph construction and label estimationinto a unified objective function.(3) W-SGRFME focuses on extending graph topology imbalance to large datasetsand integrating this concept into a scalable semi-supervised model with regularization.(4) Proposes the W-JGRFME model, addressing topological imbalance throughweighted labeled nodes with Nuclear norm Regularization.(5) Introduces the AW-SGRFME method, which uses adaptive weights for labelednodes based on dynamic class prediction.(6) Proposes a dynamic self-training approach for GSSL, integrating graphconstruction and label propagation
Spin interactions in organic molecular architectures
No full text160 p.This thesis investigates spin interactions in atomically precise organic nanostructures synthesized on metal substrates using on-surface synthesis techniques. While magnetism is usually associated with transition metals, it can also emerge in light elements like carbon through ¿-magnetism, driven by unpaired p-shell electrons. Magnetic carbon-based nanostructures are expected to exhibit unique properties such as enhanced spin delocalization and long coherence times, making them promising candidates for spintronics and quantum information applications.We employ scanning probe microscopy techniques¿mainly scanning tunneling microscopy (STM) and spectroscopy (STS)¿along with theoretical simulations to study various organic systems with differing numbers of unpaired ¿ electrons. First, we investigate the magnetic properties of a non-planar organic diradical (2-OS) on a gold substrate, demonstrating how the exchange interaction depends on molecular conformation and how it can be modified by structural or chemical changes. Next, we explore more complex nanostructures, such as a triradical nanographene (TTAT), formed by joining three [3]triangulenes via a nitrogen-doped triangulene core. The resulting system exhibits a high-spin (S=3/2) ground state, as confirmed by STM and advanced multiconfigurational calculations. Similarly, we synthesize and characterize a [3]triangulene-based macrocycle (TNS), which accumulates twelve unpaired ¿ electrons. We reveal that this nanostructure exhibits a many-body singlet ground state, with collective spin excitations accessible via inelastic electron tunneling spectroscopy. Finally, we explore strategies for fabricating two-dimensional covalent networks using open-shell triangulene units, with the aim of creating extended organic spin architectures
La adhesión de la UE al CEDH: un estudio a la luz de las sentencias del TJUE del 10 de septiembre de 2024
No full text[ES] La Unión Europea (UE o Unión) acaba de dar un paso más en la protección de los derechos fundamentales, dejando la vía abierta para su adhesión al Convenio Europeo de Derechos Humanos y de las Libertades Fundamentales (CEDH). O al menos ese es el eco que se ha hecho por la prensa de las dos recientes sentencias del Tribunal de Justicia de la Unión Europea (TJUE), asuntos Neves 77 y KS & KD. En el presente trabajo, contextualizaremos y analizaremos la mencionada jurisprudencia, y hablaremos sobre el cumplimiento por la Unión del mandato del artículo 6(2) del Tratado de la Unión Europea (TUE) a la luz de ésta. En definitiva, hablaremos sobre los principales obstáculos del proceso de adhesión; la repercusión de estas dos sentencias en él; así como del “estado de las cosas” en que se encuentra este proceso a la luz de la reciente jurisprudencia.[EU] Europar Batasunak giza eskubideen babesaren alde beste pauso bat eman berri du, Giza Eskubideen eta Oinarrizko Askatasunen Europako Hitzarmenera atxikitzeko bidea berriro ere irekiz. Behintzat, horrelaxe dio prentsak Europar Batasuneko Justizia Auzitegiak argitaratu berri dituen bi epaien inguruan, Neves 77 eta KS & KD aferetan, alegia. Lan honetan, epaiak beren testuinguruan jarri eta aztertzen saiatuko naiz, eta hauek Europar Batasunak Europar Batasunaren Ituneko 6(2) artikulua betetzeko duen betebeharrean duten eraginaren inguruan hitz egingo dut. Azken finean, atxikimendu prozesuan dauden oztopo nagusien inguruan; bi epai hauek prozesu honetan duten eraginaren; eta epaien ondorioz prozesuaren gaur egungo egoeraren inguruan hitz egingo dut.[EN] The European Union has just taken a further step in the protection of fundamental rights, paving the way for its accession to the European Convention of Human Rights and Fundamental Freedoms. At least, that is what the media has reported from the recent case law of the Court of Justice of the European Union, in cases Neves 77 and KS & KD. In this essay, I will try to give context and put these two decisions into perspective, analysing the judgments and talking about the Union’s compliance with the mandate contained in article 6(2) of the Treaty of the European Union. Ultimately, I will discuss the main obstacles in the process of accession; the impact of these two judgements on it; and the “state of affairs” of this process in light of the recent case law
Effects of recent housing legislation on Spain’s rental housing supply (2010-2024)
No full textThis thesis examines how Spanish housing legislation from 2010 to 2024 has shaped the supply
of residential rental housing, with a focus on national policies and regional cases, especially
the Basque Country, and comparisons to Madrid and Catalonia. Using a mixed-method
approach, it combines quantitative analysis of official statistics on rental supply, prices, and
housing stock with qualitative review of key laws and political debates.
The rental sector’s share of households rose from about 20% in 2010 to 25% in 2023, yet
supply growth lagged behind demand. From 2014 to 2023, nearly one million new households
were formed, but only about 683,000 new housing units were built, creating a supply deficit
and upward rent pressure
BRICS eta Afrika: etorkizun oparo bat lortzeko erronka eta aukerak
No full textGaur egungo mundu globalizatuan, ezinezkoa dirudi herrialde bakar batek bere ekonomia
sostengatu ahal izatea bakardadean “jokatuz”. Hori dela eta, herrialde ugariren arteko elkarlan
proiektuak edota hurbilketa komertzial/industrialak, errealitate ekonomikoren parte bilakatu dira
duela jada denboraldi bat. Momentu historiko honetan, gainera, bilakaera bizkorreko mundu
multipolar baten aurrean aurkitzen gara. Honen erreflexu, badira gutxinaka munduko ahaldun
ekonomiko bilakatzen ari diren garapen bideko herrialdeak, hazkunde era ezberdinak plazaratzen
dituzten estatuak eta sistema berri honen aurrean, beraien hegemonia politiko zein ekonomiko
tradizionala mantentzea kosta egiten ari zaien potentziak ere.
Kontinenteak zeharkatzen dituen aliantza ekonomikoak sortuz, badirudi BRICS
erakundeak (Brasil, Errusia, India, Txina, Hegoafrika eta partaide berriak) mundu mailako
integrazio ekonomikorako burujabetza eskuratu dezakeela, Mendebaldeko herrialdeek izandako
hegemoniarekin amaituz. Txinatarrak, adibidez, gogotsu aurkezten dira eskualde integrazio
prozesuak eta hauek biziberritzeko planak aurrera eramateko momentuan. Asiar
Azpiegituretarako Inbertsio Bankua (AIIB) bezalako garapen erakunde berriak, eskualde
mega-proiektuak edota mundu osotik zabaltzen diren itunak sortuz, beste ekimen batzuen artean
The tracking umbrella: Diverse interpretations under a common neural term
No full textPublished on 10th September, 2025.Neural tracking, the alignment of brain activity with the temporal dynamics of sensory input, is a crucial mechanism underlying perception, attention, and cognition. While this concept has gained prominence in research on speech, music, and visual processing, its definition and methodological approaches remain heterogeneous. This paper critically examines neural tracking from both theoretical and methodological perspectives, highlighting how its interpretation varies across studies. A central debate concerns whether neural tracking primarily is a byproduct of stimulus rhythmicity (train of evoked responses) or it is driven by intrinsic oscillatory synchronization (neural oscillations), particularly in speech processing—two perspectives often associated with distinct analytical methods. I review key approaches to measuring tracking, including evoked responses, multivariate temporal response functions, coherence, and phase-locking, discussing their theoretical implications and limitations. Based on available evidence, I propose that the evoked and the oscillatory perspectives should be viewed as complementary and emphasize the importance of methodological choices in accurately capturing neural tracking. Finally, I discuss the role of neural tracking in speech comprehension, advocating for future research to integrate causal methodologies, such as brain stimulation and closed-loop paradigms, to refine our understanding of its functional role.This work was supported by the Basque Government through the BERC 2022–2025 program, funded by the Spanish State Research Agency through BCBL Severo Ochoa excellence accreditation CEX2020-001010/AEI/10.13039/501100011033 and by the ERC grant Cortical Rhythms. I received financial support from the Spanish Ministry of Science, Innovation and University (grants PID2022-136991NB-I00; PCI2022-135031-2; PDC2022-133917-I00; RTI2018-096311-B-I0), and from the IKUR initiative
Deviant functional connectivity patterns in the EEG related to developmental dyslexia and their potential use for screening
No full textAvailable online 26th September, 2025.Developmental dyslexia (DD) is a common learning disorder with potential neural origins. While EEG-based brain activation measures combined with machine learning have shown promise for DD screening, these approaches often lack validation on independent participants, a crucial step for practical application. This study developed an EEG-based screening approach and investigated the neural correlates of DD in Chinese children. EEG was recorded from 130 children (82 DD, 48 typically developing; 7–11 years) during resting state (eyes-open, eyes-closed) and verbal working-memory tasks. After artifact rejection, signals were segmented and converted to functional-connectivity (FC) measures across delta, theta, alpha, and beta bands using Pearson correlation coefficients (PCC), phase-locking value (PLV), and a rho (RHO) measure. Segments were split into two non-overlapping samples to ensure participant-level independence: Sample 1 for training and five-fold cross-validation of a convolutional neural network, and Sample 2 for held-out cross-sample evaluation. Balanced accuracy (BA) served as the primary outcome, with significance assessed by permutation testing. Beta band matrices were most informative: the eyes-open beta-band RHO achieved the highest within-sample performance (BA = 97.47 %), and the eyes-closed beta-band PLV yielded above-chance cross-sample performance (BA = 64.99 %, permutation p < .001). Given the reduced cross-sample BA, further validation in larger and more diverse cohorts and other language systems is needed to establish the model’s generalizability. Discriminative FC patterns revealed that children with DD exhibited reduced temporal-parietal and central connectivity but increased frontal-central connectivity, likely reflecting compensatory mechanisms. Within the DD group, stronger FCs showed significant negative correlations with Chinese word reading accuracy and fluency. These results highlight functional network abnormalities in Chinese children with DD and offer preliminary evidence for EEG-based screening. However, current performance remains exploratory and insufficient for deployment without further refinement.This research was supported by the Health and Medical Research Fund (HMRF) of the Food and Health Bureau, Hong Kong (04152496), a Direct Grant from the Faculty of Social Sciences at the Chinese University of Hong Kong (4052177), and the General Research Fund (GRF) of the Research Grants Council of Hong Kong (RGC-GRF 14600919)