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- de Miranda de Matos Lourenço, Inês, 1994-
(författare)
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Forward and Inverse Decision-Making in Adversarial, Cooperative, and Biologically-Inspired Dynamical Systems
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Decision-making is the mechanism of using available information to develop solutions to given problems by forming preferences, beliefs, or selecting courses of action amongst several alternatives. It is the main focus of a variety of scientific fields such as robotics, finances, and neuroscience. In this thesis, we study the mechanisms that generate behavior in diverse decision-making settings (the forward problem) and how their characteristics can explain observed behavior (the inverse problem). Both problems take a central role in current research due to the desire to understand the features of system behavior, many times under situations of risk and uncertainty. We study decision-making problems in the three following settings.In the first setting, we consider a decision-maker who forms a private belief (posterior distribution) on the state of the world by filtering private information. Estimating private beliefs is a way to understand what drives decisions. This forms a foundation for predicting, and counteracting against, future actions. In the setting of adversarial systems, we answer the problems of i) how can an adversary estimate the private belief of the decision-maker by observing its decisions (under two different scenarios), and ii) how can the decision-maker protect its private belief by confusing the adversary. We exemplify the applicability of our frameworks in regime-switching Markovian portfolio allocation.In the second setting we shift from an adversarial to a cooperative scenario. We consider a teacher-student framework similar to that used in learning from demonstration and transfer learning setups. An expert agent (teacher) knows the model of a system and wants to assist a learner agent (student) in performing identification for that system but cannot directly transfer its knowledge to the student. For example, the teacher's knowledge of the system might be abstract or the teacher and student might be employing different model classes, which renders the teacher's parameters uninformative to the student. We propose correctional learning as an approach where, in order to assist the student, the teacher can intercept the observations collected from the system and modify them to maximize the amount of information the student receives about the system. We obtain finite-sample results for correctional learning of binomial systems.In the third and final setting we shift our attention to cognitive science and decision-making of biological systems, to obtain insight about the intrinsic characteristics of these systems. We focus on time perception - how humans and animals perceive the passage of time, and solve the forward problem by designing a biologically-inspired decision-making framework that replicates the mechanisms responsible for time perception. We conclude that a simulated robot equipped with our framework is able to perceive time similarly to animals - when it comes to their intrinsic mechanisms of interpreting time and performing time-aware actions. We then focus on the inverse problem. Based on the empirical action probability distribution of the agent, we are able to estimate the parameters it uses for perceiving time. Our work shows promising results when it comes to drawing conclusions regarding some of the characteristics present in biological timing mechanisms.
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| 2. |
- de Miranda de Matos Lourenço, Inês, 1994-
(författare)
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Learning from Interactions : Forward and Inverse Decision-Making for Autonomous Dynamical Systems
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Decision-making is the mechanism of using available information to generate solutions to given problems by forming preferences, beliefs, and selecting courses of action amongst several alternatives. In this thesis, we study the mechanisms that generate behavior (the forward problem) and how their characteristics can explain observed behavior (the inverse problem). Both problems play a pivotal role in contemporary research due to the desire to design sophisticated autonomous agents that serve as the building blocks for a smart society, amidst complexity, risk, and uncertainty. This work explores different parts of the autonomous decision-making process where agents learn from interacting with each other and the environment that surrounds them. We address fundamental problems of behavior modeling, parameter estimation in the form of beliefs, distributions, and reward functions, and then finally interactions with other agents; which lay the foundation for a complete and integrative framework for decision-making and learning. The thesis is divided into four parts, each featuring a different information exchange paradigm.First, we model the forward problem of how a decision-maker forms beliefs about the world and the inverse problem of estimating these beliefs from the agent’s behavior. The private belief (posterior distribution) on the state of the world is formed according to a hidden Markov model by filtering private information. The ability to estimate private beliefs forms a foundation for predicting and counteracting against future actions. We answer the problems of i) how the private belief of the decision-maker can be estimated by observing its decisions (under two different scenarios), and ii) how the decision-maker can protect its private belief from an adversary by confusing it. We exemplify the applicability of our frameworks in regime-switching Markovian portfolio allocation.In the second part, we study forward decision-making of biological systems and the inverse problem of how to obtain insight into their intrinsic characteristics. We focus on time perception – how humans and animals perceive the passage of time – and design a biologically-inspired decision-making framework using reinforcement learning that replicates timing mechanisms. We show that a simulated robot equipped with our framework is able to perceive time similarly to animals, and that by analyzing its performed actions we are able to estimate the parameters of timing mechanisms.Next, we consider teacher-student settings where a teacher agent can intervene with the decision-making process of a student agent to assist it in performing a task. In the third part, we propose correctional learning as an approach where the teacher can intercept the observations the student collects from the system and modify them to improve the estimation process of the student. We provide finite-sample results for batch correctional learning in system identification, generalize it to more complex systems using optimal transport, and lower-bound improvements on the estimate’s variance for the online case.Decision-making in teacher-student settings like the previous one requires both agents to have aligned models of understanding of each other. In the fourth and last part of this thesis, the teacher can, instead, alter the decisions of the decision-maker in a human-robot interaction setting. We use a confidence-based misalignment detection method that enables the robot to update its knowledge proportionally to its confidence in the human corrections and propose a framework to disambiguate between misalignment caused by incorrectly learned features that do not generalize to new environments and features entirely missing from the robot’s model. We demonstrate the proposed framework in a 7 degrees-of-freedom robot manipulator with physical human corrections and show how to initiate the model realignment process once misalignment is detected.
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| 3. |
- Giska, Iwona, et al.
(författare)
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Introgression drives repeated evolution of winter coat color polymorphism in hares
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:48, s. 24150-24156
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Tidskriftsartikel (refereegranskat)abstract
- Changing from summer-brown to winter-white pelage or plumage is a crucial adaptation to seasonal snow in more than 20 mammal and bird species. Many of these species maintain nonwhite winter morphs, locally adapted to less snowy conditions, which may have evolved independently. Mountain hares (Lepus timidus) from Fennoscandia were introduced into the Faroe Islands in 1855. While they were initially winter-white, within ∼65 y all Faroese hares became winter-gray, a morph that occurs in the source population at low frequency. The documented population history makes this a valuable model for understanding the genetic basis and evolution of the seasonal trait polymorphism. Through whole-genome scans of differentiation and single-nucleotide polymorphism (SNP) genotyping, we associated winter coat color polymorphism to the genomic region of the pigmentation gene Agouti, previously linked to introgression-driven winter coat color variation in the snowshoe hare (Lepus americanus). Lower Agouti expression in the skin of winter-gray individuals during the autumn molt suggests that regulatory changes may underlie the color polymorphism. Variation in the associated genomic region shows signatures of a selective sweep in the Faroese population, suggesting that positive selection drove the fixation of the variant after the introduction. Whole-genome analyses of several hare species revealed that the winter-gray variant originated through introgression from a noncolor changing species, in keeping with the history of ancient hybridization between the species. Our findings show the recurrent role of introgression in generating winter coat color variation by repeatedly recruiting the regulatory region of Agouti to modulate seasonal coat color change.
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| 4. |
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| 5. |
- Mikocka-Walus, Antonina, et al.
(författare)
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Exploring the Relationship Between Self-Isolation and Distress Among People with Gastrointestinal Disorders During the COVID-19 Pandemic
- 2022
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Ingår i: Journal of clinical psychology in medical settings. - : Springer. - 1068-9583 .- 1573-3572. ; 29:3, s. 654-665
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to explore the association between perceived isolation and symptoms of distress in people with GI disorders at the time of the pandemic; and to examine factors which moderate this relationship. This online cross-sectional survey was advertised in May-September 2020 via patient organisations and associated social media. Overall, 831 people (82% female, mean age 49 years) from 27 countries participated. A significant relationship between social isolation and psychological distress was noted (r = .525, p < .001). GI symptoms moderated the association between isolation and distress (B = .047, t = 2.47, p = .015). Interventions targeting these factors may help to reduce distress in people with GI disorders at the time of major stressors such as the COVID-19 pandemic.
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| 6. |
- Redmer, Torben, et al.
(författare)
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JUN mediates the senescence associated secretory phenotype and immune cell recruitment to prevent prostate cancer progression
- 2024
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Ingår i: Molecular Cancer. - : BioMed Central (BMC). - 1476-4598. ; 23:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Prostate cancer develops through malignant transformation of the prostate epithelium in a stepwise, mutation-driven process. Although activator protein-1 transcription factors such as JUN have been implicated as potential oncogenic drivers, the molecular programs contributing to prostate cancer progression are not fully understood.Methods: We analyzed JUN expression in clinical prostate cancer samples across different stages and investigated its functional role in a Pten-deficient mouse model. We performed histopathological examinations, transcriptomic analyses and explored the senescence-associated secretory phenotype in the tumor microenvironment.Results: Elevated JUN levels characterized early-stage prostate cancer and predicted improved survival in human and murine samples. Immune-phenotyping of Pten-deficient prostates revealed high accumulation of tumor-infiltrating leukocytes, particularly innate immune cells, neutrophils and macrophages as well as high levels of STAT3 activation and IL-1β production. Jun depletion in a Pten-deficient background prevented immune cell attraction which was accompanied by significant reduction of active STAT3 and IL-1β and accelerated prostate tumor growth. Comparative transcriptome profiling of prostate epithelial cells revealed a senescence-associated gene signature, upregulation of pro-inflammatory processes involved in immune cell attraction and of chemokines such as IL-1β, TNF-α, CCL3 and CCL8 in Pten-deficient prostates. Strikingly, JUN depletion reversed both the senescence-associated secretory phenotype and senescence-associated immune cell infiltration but had no impact on cell cycle arrest. As a result, JUN depletion in Pten-deficient prostates interfered with the senescence-associated immune clearance and accelerated tumor growth.Conclusions: Our results suggest that JUN acts as tumor-suppressor and decelerates the progression of prostate cancer by transcriptional regulation of senescence- and inflammation-associated genes. This study opens avenues for novel treatment strategies that could impede disease progression and improve patient outcomes. Graphical Abstract: (Figure presented.).
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| 7. |
- Sanchez-Grande, Ana, et al.
(författare)
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Surface-Assisted Synthesis of N-Containing pi-Conjugated Polymers
- 2022
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Ingår i: Advanced Science. - : Wiley. - 2198-3844. ; 9:19
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Tidskriftsartikel (refereegranskat)abstract
- On-surface synthesis has recently emerged as a powerful strategy to design conjugated polymers previously precluded in conventional solution chemistry. Here, an N-containing pentacene-based precursor (tetraazapentacene) is ex-professo synthesized endowed with terminal dibromomethylene (:CBr2) groups to steer homocoupling via dehalogenation on metallic supports. Combined scanning probe microscopy investigations complemented by theoretical calculations reveal how the substrate selection drives different reaction mechanisms. On Ag(111) the dissociation of bromine atoms at room temperature triggers the homocoupling of tetraazapentacene units together with the binding of silver adatoms to the nitrogen atoms of the monomers giving rise to a N-containing conjugated coordination polymer (P1). Subsequently, P1 undergoes ladderization at 200 degrees C, affording a pyrrolopyrrole-bridged conjugated polymer (P2). On Au(111) the formation of the intermediate polymer P1 is not observed and, instead, after annealing at 100 degrees C, the conjugated ladder polymer P2 is obtained, revealing the crucial role of metal adatoms on Ag(111) as compared to Au(111). Finally, on Ag(100) the loss of :CBr2 groups affords the formation of tetraazapentacene monomers, which coexist with polymer P1. Our results contribute to introduce protocols for the synthesis of N-containing conjugated polymers, illustrating the selective role of the metallic support in the underlying reaction mechanisms.
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| 8. |
- Vázquez, Inês, et al.
(författare)
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Psychological Adjustment Profiles of LGBTQ+ Young Adults Residing with Their Parents during the COVID-19 Pandemic : An International Study
- 2023
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 20:4
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic has been associated with poor mental health symptoms, particularly among vulnerable populations such as LGBTQ+ individuals. In the present study, we aimed to (i) identify different psychological adjustment profiles among LGBTQ+ young adults during the COVID-19 pandemic and compare LGBTQ+ young adults in relation to (ii) sociodemographic characteristics and COVID-19-related experiences and (iii) the internal and external protective resources associated with each adjustment profile. An online questionnaire was administered to 1699 LGBTQ+ young adults from six countries (Brazil, Chile, Italy, Portugal, Sweden, and the UK). A cluster analysis was conducted, and four profiles of psychological adjustment were identified: unchallenged, resilient, distressed, and at-risk. The at-risk cluster scored lowest in social support (particularly from family). The profiles of participants who experienced the highest levels of pandemic adversity (at-risk and resilient) comprised mostly South American participants, those under lockdown at the time of survey completion, those who self-identified as transgender and non-binary, and those with a plurisexual sexual orientation. Interventions should consider strategies to help young adults maintain support systems and reinforce the value of positive family relationships. Specific groups within the LGBTQ+ community that seem to be in a particularly vulnerable situation may need additional tailored support.
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