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Search Results (2,101)

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Keywords = individual identity

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28 pages, 1063 KiB  
Article
A Digital Identity Blockchain Ecosystem: Linking Government-Certified and Uncertified Tokenized Objects
by Juan-Carlos López-Pimentel, Javier Gonzalez-Sanchez and Luis Alberto Morales-Rosales
Appl. Sci. 2025, 15(15), 8577; https://doi.org/10.3390/app15158577 (registering DOI) - 1 Aug 2025
Abstract
This paper presents a novel digital identity ecosystem built upon a hierarchical structure of Blockchain tokens, where both government-certified and uncertified tokens can coexist to represent various attributes of an individual’s identity. At the core of this system is the government, which functions [...] Read more.
This paper presents a novel digital identity ecosystem built upon a hierarchical structure of Blockchain tokens, where both government-certified and uncertified tokens can coexist to represent various attributes of an individual’s identity. At the core of this system is the government, which functions as a trusted authority capable of creating entities and issuing a unique, non-replicable digital identity token for each one. Entities are the exclusive owners of their identity tokens and can attach additional tokens—such as those issued by the government, educational institutions, or financial entities—to form a verifiable, token-based digital identity tree. This model accommodates a flexible identity framework that enables decentralized yet accountable identity construction. Our contributions include the design of a digital identity system (supported by smart contracts) that enforces uniqueness through state-issued identity tokens while supporting user-driven identity formation. The model differentiates between user types and certifies tokens according to their source, enabling a scalable and extensible structure. We also analyze the economic, technical, and social feasibility of deploying this system, including a breakdown of transaction costs for key stakeholders such as governments, end-users, and institutions like universities. Considering the benefits of blockchain, implementing a digital identity ecosystem in this technology is economically viable for all involved stakeholders. Full article
(This article belongs to the Special Issue Advanced Blockchain Technology and Its Applications)
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14 pages, 253 KiB  
Article
Marketing and Perceived Value of Differentiated Quality Labels in Extremadura’s Agri-Food Sector
by Alejandro Maya Reyes, Elena Muñoz-Muñoz, Carlos Díaz Caro and Ángel-Sabino Mirón Sanguino
Foods 2025, 14(15), 2707; https://doi.org/10.3390/foods14152707 (registering DOI) - 1 Aug 2025
Abstract
The present study focuses on the attractiveness and perceived value of differentiated quality labels, such as the Protected Designation of Origin (PDO) and Protected Geographical Indication (PGI), for agri-food products from Extremadura (Spain). In doing so, it addresses a gap in the scientific [...] Read more.
The present study focuses on the attractiveness and perceived value of differentiated quality labels, such as the Protected Designation of Origin (PDO) and Protected Geographical Indication (PGI), for agri-food products from Extremadura (Spain). In doing so, it addresses a gap in the scientific literature concerning consumer behavior toward products bearing these certifications. The results show that awareness of these quality schemes is significantly higher among middle-aged and older individuals, underscoring the need for more modern and targeted communication strategies. The findings highlight the strategic role of agri-food marketing in promoting certified products and emphasize the importance of bridging the generational gap in consumer education. Overall, differentiated quality schemes are perceived as strategic tools to enhance the competitiveness of local products, strengthen cultural identity, and foster sustainable rural economies. Furthermore, this study identifies a negative relationship between the consumption of certified products and the awareness of certification and a positive relationship with the willingness to pay a premium. Consumers with greater awareness tend consume these products less, although they are more willing to pay higher prices for items bearing quality labels. Full article
(This article belongs to the Section Sensory and Consumer Sciences)
22 pages, 1081 KiB  
Article
A New Method in Certification of Buildings: BCA Method and a Case Study
by Cevdet Emin Ekinci and Belkis Elyigit
Sustainability 2025, 17(15), 6986; https://doi.org/10.3390/su17156986 (registering DOI) - 1 Aug 2025
Abstract
This study investigates the engineering characteristics of a newly commissioned higher education building through the Bioharmological Conformity Assessment (BCA) method, specifically using the 2020vEB version. The BCA is a novel evaluation approach that assesses whether a building aligns with the identity of its [...] Read more.
This study investigates the engineering characteristics of a newly commissioned higher education building through the Bioharmological Conformity Assessment (BCA) method, specifically using the 2020vEB version. The BCA is a novel evaluation approach that assesses whether a building aligns with the identity of its users and its intended function. The engineering attributes of the structure were assessed across 12 core criteria, encompassing a total of 600 individual parameters. Findings from the BCA inspection indicate that the newly completed building falls into the category of “Near-Standard Building/Minor Modifications Required.” The BCA score was calculated as 398.73, corresponding to a deficiency rate of 25.50%. Notably, significant shortcomings were observed in categories such as user identity and intended use, Physical Characteristics of the Space, and Ecological and Seismological Suitability. Consequently, targeted improvements are necessary to align the building with bioharmological principles, requiring only minor adjustments to rectify the identified deficiencies. Full article
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31 pages, 427 KiB  
Article
From The Demon to the Secret Voice: Archetypal Echoes and Oral Culture in 19th Century Romantic Poetry
by Gül Mükerrem Öztürk
Humanities 2025, 14(8), 160; https://doi.org/10.3390/h14080160 - 31 Jul 2025
Abstract
The first half of the 19th century witnessed the rise of Romantic poetry, which focused in depth on individual consciousness, inner worlds, and metaphysical inquiries. This poetic orientation became particularly evident in works centred on themes such as solitude, alienation, and existential quests. [...] Read more.
The first half of the 19th century witnessed the rise of Romantic poetry, which focused in depth on individual consciousness, inner worlds, and metaphysical inquiries. This poetic orientation became particularly evident in works centred on themes such as solitude, alienation, and existential quests. Within this context, the present study aims to examine the archetypal and poetic resonances of the poetic voice in Mihail Lermontov’s poem The Demon, based on its sixth and final version dated 1841, in relation to Nikoloz Baratashvili’s poem Secret Voice. Lermontov’s poem is analyzed through the English translation by Charles Johnston, published in 1983, while Baratashvili’s poem is discussed based on the 24-line version included in the fifth edition (1895) of the anthology Poems and Letters (Leksebi da Tserilebi). This study explores the thematic and structural similarities between the two poems within the framework of comparative literature and psychoanalytic criticism, focusing on Romantic archetypes, the uncanny, the shadow figure, and ontological solitude. Furthermore, the dialogue established between Lermontov’s demonic narrator and Baratashvili’s introspective poetic voice reopens discussions on the boundaries of cultural memory, oral narrative patterns, and poetic identity. Ultimately, this comparative analysis reveals the implicit influences of The Demon on Georgian poetry and discusses the intercultural resonances of themes such as voice, self, and archetype in Romantic poetry. Full article
(This article belongs to the Section Literature in the Humanities)
11 pages, 1419 KiB  
Article
Genetic Evidence of Yersinia pestis from the First Pandemic
by Swamy R. Adapa, Karen Hendrix, Aditya Upadhyay, Subhajeet Dutta, Andrea Vianello, Gregory O’Corry-Crowe, Jorge Monroy, Tatiana Ferrer, Elizabeth Remily-Wood, Gloria C. Ferreira, Michael Decker, Robert H. Tykot, Sucheta Tripathy and Rays H. Y. Jiang
Genes 2025, 16(8), 926; https://doi.org/10.3390/genes16080926 (registering DOI) - 31 Jul 2025
Abstract
Background/Objectives: The Plague of Justinian marked the beginning of the First Pandemic (541–750 CE), yet no genomic evidence of Yersinia pestis has previously been recovered from the Eastern Mediterranean, where the outbreak was first recorded. This study aimed to determine whether Y. pestis [...] Read more.
Background/Objectives: The Plague of Justinian marked the beginning of the First Pandemic (541–750 CE), yet no genomic evidence of Yersinia pestis has previously been recovered from the Eastern Mediterranean, where the outbreak was first recorded. This study aimed to determine whether Y. pestis was present in a mid-6th to early 7th century mass grave in Jerash, Jordan, and to characterize its genome within the broader context of First Pandemic strains. Methods: We analyzed samples from multiple individuals recovered from the Jerash mass grave. Initial screening for potential pathogen presence was conducted using proteomics. Select samples were subjected to ancient DNA extraction and whole genome sequencing. Comparative genomic and phylogenetic analyses were conducted to assess strain identity and evolutionary placement. Results: Genomic sequencing recovered Y. pestis DNA from five individuals, revealing highly similar genomes. All strains clustered tightly with other First Pandemic lineages but were notably recovered from a region geographically close to the pandemic’s historical epicenter for the first time. The near-identical genomes across diverse individuals suggest an outbreak of a single circulating lineage at the time of this outbreak. Conclusions: This study provides the first genomic evidence of Y. pestis in the Eastern Mediterranean during the First Pandemic, linking archaeological findings with pathogen genomics near the origin point of the Plague of Justinian. Summary Sentence: Genomic evidence links Y. pestis to the First Pandemic in an ancient city. Full article
(This article belongs to the Section Microbial Genetics and Genomics)
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16 pages, 3339 KiB  
Article
Accurate Identification of Native Asian Honey Bee Populations in Jilong (Xizang, China) by Population Genomics and Deep Learning
by Zhiyu Liu, Yongqiang Xu, Wei Sun, Bing Yang, Tenzin Nyima, Zhuoma Pubu, Xin Zhou, Wa Da and Shiqi Luo
Insects 2025, 16(8), 788; https://doi.org/10.3390/insects16080788 (registering DOI) - 31 Jul 2025
Viewed by 7
Abstract
The Jilong Valley, situated in Rikaze, Xizang, China, is characterized by its complex topography and variable climatic conditions, providing a suitable habitat for Apis cerana Fabricius, 1793. To facilitate the conservation of germplasm resources and maintain genetic diversity, it is imperative to elucidate [...] Read more.
The Jilong Valley, situated in Rikaze, Xizang, China, is characterized by its complex topography and variable climatic conditions, providing a suitable habitat for Apis cerana Fabricius, 1793. To facilitate the conservation of germplasm resources and maintain genetic diversity, it is imperative to elucidate the population structure and lineage differentiation of A. cerana within this ecologically distinct region. In this study, we collected A. cerana specimens from 12 geographically disparate locations across various altitudinal gradients within the Jilong Valley, and also integrated publicly available sequencing data of A. cerana from various regions across mainland Asia. In total, our analysis encompassed sequencing data from 296 individuals. Population structure analyses based on SNP data revealed that A. cerana in Jilong represents a genetically distinct population that differs markedly from other regional A. cerana populations in terms of genetic lineage, although its subspecies identity remains to be confirmed. Through screening based on FST values, we identified SNP loci that contribute significantly to distinguishing between Jilong and non-Jilong A. cerana. Using these loci, the convolutional neural network model TraceNet was trained, which demonstrated specific recognition capabilities for Jilong versus non-Jilong A. cerana. This further confirmed the universality and efficiency of TraceNet in identifying honey bee lineages. These findings contribute valuable insights for the identification and conservation of A. cerana germplasm resources in specific geographical regions. Full article
(This article belongs to the Section Insect Systematics, Phylogeny and Evolution)
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29 pages, 342 KiB  
Article
The Intersection of Giftedness, Disability, and Cultural Identity: A Case Study of a Young Asian American Boy
by Tammy Jean Byrd, Ty’Bresha Ebony Glass, Ophélie Allyssa Desmet and F. Richard Olenchak
Behav. Sci. 2025, 15(8), 1036; https://doi.org/10.3390/bs15081036 - 30 Jul 2025
Viewed by 237
Abstract
The present research examines the intersections of giftedness, disability status, and cultural identity through the case of Kent, a nine-year-old Asian American boy who is not only profoundly gifted but has also been diagnosed with autism spectrum disorder (ASD), attention deficit hyperactivity disorder [...] Read more.
The present research examines the intersections of giftedness, disability status, and cultural identity through the case of Kent, a nine-year-old Asian American boy who is not only profoundly gifted but has also been diagnosed with autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and possibly developmental coordination disorder (DCD). This study offers a comprehensive exploration of how these overlapping factors shape Kent’s early talent development and educational experiences, while also highlighting the challenges faced by his family and their need for a personalized, holistic support system tailored to his unique combination of abilities and disabilities. While Kent’s case is not generalizable, it underscores the critical importance of understanding the dynamic interplay among giftedness, disability status, and cultural identity in developing effective educational strategies. Furthermore, we advocate for personalized interventions that extend beyond conventional approaches, such as applied behavior analysis (ABA), to adequately address the complex needs of multi-exceptional individuals like Kent. Full article
21 pages, 695 KiB  
Review
Physicians’ and Residents’ Well-Being in Ecological System: A Scoping Review of Positive Deviance Strategies
by Hyoseon Choi, Janghee Park, Sanghee Yeo, Seung-Joo Na and Hyojin Kwon
Healthcare 2025, 13(15), 1856; https://doi.org/10.3390/healthcare13151856 - 30 Jul 2025
Viewed by 181
Abstract
Background/Objectives: It is essential to explore and disseminate positive deviance strategies that promote resilience, mindfulness, and well-being beyond stress and burnout reduction strategies for residents and physicians who experience high levels of occupational stress. This scoping review maps studies that investigate positive [...] Read more.
Background/Objectives: It is essential to explore and disseminate positive deviance strategies that promote resilience, mindfulness, and well-being beyond stress and burnout reduction strategies for residents and physicians who experience high levels of occupational stress. This scoping review maps studies that investigate positive deviance strategies to enhance the well-being of residents and physicians. Methods: A scoping review was conducted by PRISMA guidelines to identify English-language studies on strategies for physician well-being. PubMed, MEDLINE, Embase, and ERIC were searched using terms related to well-being, coping, and medical education. Results: Among the 38 studies included, 17 (44.7%) targeted physicians in graduate medical education (GME), while 19 (50%) focused on continuing medical education (CME). Positive deviance strategies were identified in 26 studies and were most frequently implemented at the microsystem level, such as small group interventions (e.g., coaching, mentoring, and workshops). These strategies addressed individual and organisational factors that contribute to physician well-being and were associated with improvements in life satisfaction, resilience, professional identity, and psychological safety. The review found that positive deviance strategies were often proactive, values-driven, and disseminated organically over time, emphasising the importance of longitudinal engagement and sustained institutional support. Conclusions: This scoping review highlights the growing use of positive deviance strategies, especially at the microsystem level, to promote physician well-being. These approaches emphasise sustainable, values-driven practices and may offer effective, context-sensitive solutions within healthcare systems. Full article
(This article belongs to the Special Issue Occupational Stress: Support, Coping, and Control)
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19 pages, 287 KiB  
Article
Faith and Finance: Understanding Muslim Consumers’ Identity in Pakistan’s Traditional Banking Sector
by Samreen Ashraf, Juliet Memery and Martyn Polkinghorne
Businesses 2025, 5(3), 30; https://doi.org/10.3390/businesses5030030 - 29 Jul 2025
Viewed by 150
Abstract
Although research on religion has gained increasing attention, few studies have examined its connection to consumer identity and how it influences purchasing decisions. This gap is especially noticeable when it comes to decision-making around religious services. Previous studies on what influences consumers’ choice [...] Read more.
Although research on religion has gained increasing attention, few studies have examined its connection to consumer identity and how it influences purchasing decisions. This gap is especially noticeable when it comes to decision-making around religious services. Previous studies on what influences consumers’ choice of banks have produced mixed findings on the role of religion. This study explores how multiple identities shape the decision to use non-Islamic banking services in Pakistan, where Muslim consumers can choose between Islamic (religious) and non-Islamic (non-religious) banking options. Using a qualitative approach, the research focuses on Muslims who opt for non-Islamic banking to understand the factors behind their choice. Findings reveal that role identity—especially as a son or daughter—plays a key role in bank selection, even when religion is important to the individual. However, identity conflicts arise as people navigate different aspects of their identity. Surprisingly, group identity had little influence on these banking decisions. Full article
15 pages, 265 KiB  
Article
The Educational Community and the Inclusion of LGBTIQ+ Students: Towards a Rainbow School Free from LGBTIQphobia
by Begoña Sánchez-Torrejón and Macarena Machín Álvarez
Educ. Sci. 2025, 15(8), 971; https://doi.org/10.3390/educsci15080971 - 28 Jul 2025
Viewed by 140
Abstract
In a society that advocates for human rights, a moralistic, needs-based approach is incompatible with policies and practices that ensure educational inclusion for all individuals regardless of gender identity or sexual orientation. This study analyses the perspectives of members of the educational community [...] Read more.
In a society that advocates for human rights, a moralistic, needs-based approach is incompatible with policies and practices that ensure educational inclusion for all individuals regardless of gender identity or sexual orientation. This study analyses the perspectives of members of the educational community on sex–gender diversity. Specifically, it presents the views of 32 individuals from four primary schools located in southern Andalusia. A qualitative methodology based on interviews and content analysis was employed, supported by NVIVO12 software. The findings reveal differing understandings of sex–gender diversity; the school’s stance on such diversity and, particularly, on LGBTIQ+phobia; as well as the role of initial teacher training in this area. Full article
18 pages, 271 KiB  
Article
AI Pioneers and Stragglers in Greece: Challenges, Gaps, and Opportunities for Journalists and Media
by Sotirios Triantafyllou, Andreas M. Panagopoulos and Panagiotis Kapos
Societies 2025, 15(8), 209; https://doi.org/10.3390/soc15080209 - 28 Jul 2025
Viewed by 326
Abstract
Media organizations are experiencing ongoing transformation, increasingly driven by the advancement of AI technologies. This development has begun to link journalists with generative systems and synthetic technologies. Although newsrooms worldwide are exploring AI adoption to improve information sourcing, news production, and distribution, a [...] Read more.
Media organizations are experiencing ongoing transformation, increasingly driven by the advancement of AI technologies. This development has begun to link journalists with generative systems and synthetic technologies. Although newsrooms worldwide are exploring AI adoption to improve information sourcing, news production, and distribution, a gap exists between resource-rich organizations and those with limited means. Since ChatGPT 3.5 was released on 30 November 2022, Greek media and journalists have gained the ability to use and explore AI technology. In this study, we examine the use of AI in Greek newsrooms, as well as journalists’ reflections and concerns. Through qualitative analysis, our findings indicate that the adoption and integration of these tools in Greek newsrooms is marked by the lack of formal institutional policies, leading to a predominantly self-directed and individualized use of these technologies by journalists. Greek journalists engage with AI tools both professionally and personally, often without organizational guidance or formal training. This issue may compromise the quality of journalism due to the absence of established guidelines. Consequently, individuals may produce content that is inconsistent with the media outlet’s identity or that disseminates misinformation. Age, gender, and newsroom roles do not constitute limiting factors for this “experimentation”, as survey participants showed familiarity with this technology. In addition, in some cases, the disadvantages of specific tools regarding qualitative results in Greek are inhibiting factors for further exploration and use. All these points to the need for immediate training, literacy, and ethical frameworks. Full article
20 pages, 5053 KiB  
Article
Epifaunal Assemblages of the Fan Mussel Atrina fragilis (Mollusca: Bivalvia) in the Sea of Marmara
by Melih Ertan Çinar, Mehmet Baki Yokeş, Deniz Erdogan-Dereli, Sermin Açik and Alper Evcen
Biology 2025, 14(8), 945; https://doi.org/10.3390/biology14080945 - 27 Jul 2025
Viewed by 234
Abstract
Dense aggregations of species in the family Pinnidae give soft substrata a specific characterization. They may influence the biological and physical properties of the surrounding sediments. Bottom-trawl samplings performed in the Sea of Marmara revealed populations of a large pinnid species, particularly at [...] Read more.
Dense aggregations of species in the family Pinnidae give soft substrata a specific characterization. They may influence the biological and physical properties of the surrounding sediments. Bottom-trawl samplings performed in the Sea of Marmara revealed populations of a large pinnid species, particularly at depths of 40–45 m in soft substrata. Both morphological and DNA analyses confirmed the species’ taxonomic identity as Atrina fragilis. This species had a population density ranging from 31 to 469 ind.km−2, and the shell lengths ranged from 21.3 to 31 cm. A total of 47 macrozoobenthic species belonging to eight taxonomic groups were found on the shells of ten live and nine dead A. fragilis individuals. Polychaeta accounted for 53% of the total number of species and 75% of the total number of individuals. Among these species, Protula tubularia and Serpula concharum comprised almost 30% of all epifaunal populations. Community parameters changed according to the shell length and width. Different faunal assemblages were encountered on the shells. Given the ecological significance of A. fragilis as both a habitat-forming and sensitive benthic species, conservation measures should prioritize the protection of known habitats and the regulation of activities that lead to seabed disturbance. Full article
(This article belongs to the Special Issue Epibiosis in Aquatic Environments)
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14 pages, 375 KiB  
Article
Willingness to Become a Living Kidney Donor to a Stranger Among Polish Health Care Professionals Employed in a Dialysis Center: A National Cross-Sectional Study
by Paulina Kurleto, Irena Milaniak, Lucyna Tomaszek and Wioletta Mędrzycka-Dabrowska
J. Clin. Med. 2025, 14(15), 5282; https://doi.org/10.3390/jcm14155282 - 25 Jul 2025
Viewed by 321
Abstract
Background: Kidney transplantation from a living donor is considered the most beneficial form of treatment for end-stage renal failure, which, in addition to providing patients with better treatment results, significantly improves their quality of life. Understanding factors that influence the willingness to [...] Read more.
Background: Kidney transplantation from a living donor is considered the most beneficial form of treatment for end-stage renal failure, which, in addition to providing patients with better treatment results, significantly improves their quality of life. Understanding factors that influence the willingness to donate kidneys to strangers is critical in promoting and expanding the living donor pool. When considering the decision to become an altruistic kidney donor, individuals must evaluate multiple factors, including the identity of the recipient and their own perceived level of safety. This study aimed to assess the willingness of dialysis center employees to act as living kidney donors for a stranger. Methods: We conducted a cross-sectional study from February 2023 to June 2024 among dialysis specialists across Poland. The study involved 1093 people (doctors and nurses). The study used our survey questionnaire and standardized tools. Results: Nurses (vs. physicians) and those who advocated the regulation of unspecified living kidney donation in Poland, did not believe in the risk of organ trafficking, and would donate a kidney to a husband/wife or friend and accept kidney transplantation from a husband/wife were more likely to donate a kidney to a stranger. Furthermore, respondents who accepted a loved one’s decision to donate a kidney to a stranger were significantly more willing to donate a kidney to such a person themselves. Perceived self-efficacy was positively associated with the willingness to donate a kidney to a stranger. Conclusions: Less than half of healthcare professionals supported unspecific living organ donation in Poland, and nurses were more willing to donate than physicians. The factors supporting the decision generally included knowledge about organ donation and transplantation, a lack of fear of organ trafficking, and attitudes towards donation. Full article
(This article belongs to the Section Nephrology & Urology)
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35 pages, 638 KiB  
Review
The Influence of Circadian Rhythms on Transcranial Direct Current Stimulation (tDCS) Effects: Theoretical and Practical Considerations
by James Chmiel and Agnieszka Malinowska
Cells 2025, 14(15), 1152; https://doi.org/10.3390/cells14151152 - 25 Jul 2025
Viewed by 467
Abstract
Transcranial direct current stimulation (tDCS) can modulate cortical excitability in a polarity-specific manner, yet identical protocols often produce inconsistent outcomes across sessions or individuals. This narrative review proposes that much of this variability arises from the brain’s intrinsic temporal landscape. Integrating evidence from [...] Read more.
Transcranial direct current stimulation (tDCS) can modulate cortical excitability in a polarity-specific manner, yet identical protocols often produce inconsistent outcomes across sessions or individuals. This narrative review proposes that much of this variability arises from the brain’s intrinsic temporal landscape. Integrating evidence from chronobiology, sleep research, and non-invasive brain stimulation, we argue that tDCS produces reliable, polarity-specific after-effects only within a circadian–homeostatic “window of efficacy”. On the circadian (Process C) axis, intrinsic alertness, membrane depolarisation, and glutamatergic gain rise in the late biological morning and early evening, whereas pre-dawn phases are marked by reduced excitability and heightened inhibition. On the homeostatic (Process S) axis, consolidated sleep renormalises synaptic weights, widening the capacity for further potentiation, whereas prolonged wakefulness saturates plasticity and can even reverse the usual anodal/cathodal polarity rules. Human stimulation studies mirror this two-process fingerprint: sleep deprivation abolishes anodal long-term-potentiation-like effects and converts cathodal inhibition into facilitation, while stimulating at each participant’s chronotype-aligned (phase-aligned) peak time amplifies and prolongs after-effects even under equal sleep pressure. From these observations we derive practical recommendations: (i) schedule excitatory tDCS after restorative sleep and near the individual wake-maintenance zone; (ii) avoid sessions at high sleep pressure or circadian troughs; (iii) log melatonin phase, chronotype, recent sleep and, where feasible, core temperature; and (iv) consider mild pre-heating or time-restricted feeding as physiological primers. By viewing Borbély’s two-process model and allied metabolic clocks as adjustable knobs for plasticity engineering, this review provides a conceptual scaffold for personalised, time-sensitive tDCS protocols that could improve reproducibility in research and therapeutic gain in the clinic. Full article
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30 pages, 4578 KiB  
Article
Unpacking Performance Variability in Deep Reinforcement Learning: The Role of Observation Space Divergence
by Sooyoung Jang and Ahyun Lee
Appl. Sci. 2025, 15(15), 8247; https://doi.org/10.3390/app15158247 - 24 Jul 2025
Viewed by 170
Abstract
Deep Reinforcement Learning (DRL) algorithms often exhibit significant performance variability across different training runs, even with identical settings. This paper investigates the hypothesis that a key contributor to this variability is the divergence in the observation spaces explored by individual learning agents. We [...] Read more.
Deep Reinforcement Learning (DRL) algorithms often exhibit significant performance variability across different training runs, even with identical settings. This paper investigates the hypothesis that a key contributor to this variability is the divergence in the observation spaces explored by individual learning agents. We conducted an empirical study using Proximal Policy Optimization (PPO) agents trained on eight Atari environments. We analyzed the collected agent trajectories by qualitatively visualizing and quantitatively measuring the divergence in their explored observation spaces. Furthermore, we cross-evaluated the learned actor and value networks, measuring the average absolute TD-error, the RMSE of value estimates, and the KL divergence between policies to assess their functional similarity. We also conducted experiments where agents were trained from identical network initializations to isolate the source of this divergence. Our findings reveal a strong correlation: environments with low-performance variance (e.g., Freeway) showed high similarity in explored observation spaces and learned networks across agents. Conversely, environments with high-performance variability (e.g., Boxing, Qbert) demonstrated significant divergence in both explored states and network functionalities. This pattern persisted even when agents started with identical network weights. These results suggest that differences in experiential trajectories, driven by the stochasticity of agent–environment interactions, lead to specialized agent policies and value functions, thereby contributing substantially to the observed inconsistencies in DRL performance. Full article
(This article belongs to the Special Issue Advancements and Applications in Reinforcement Learning)
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