A study on affect model validity : nominal vs ordinal labels

The question of representing emotion computationally remains largely unanswered: popular approaches require annotators to assign a magnitude (or a class) of some emotional dimension, while an alternative is to focus on the relationship between two or more options. Recent evidence in affective computing suggests that following a methodology of ordinal annotations and processing leads to better reliability and validity of the model. This paper compares the generality of classification methods versus preference learning methods in predicting the levels of arousal in two widely used affective datasets. Findings of this initial study further validate the hypothesis that approaching affect labels as ordinal data and building models via preference learning yields models of better validity.peer-reviewe

Collaborative agent gameplay in the Pandemic board game

While artificial intelligence has been applied to control players’ decisions in board games for over half a century, little attention is given to games with no player competition. Pandemic is an exemplar collaborative board game where all players coordinate to overcome challenges posed by events occurring during the game’s progression. This paper proposes an artificial agent which controls all players’ actions and balances chances of winning versus risk of losing in this highly stochastic environment. The agent applies a Rolling Horizon Evolutionary Algorithm on an abstraction of the game-state that lowers the branching factor and simulates the game’s stochasticity. Results show that the proposed algorithm can find winning strategies more consistently in different games of varying difficulty. The impact of a number of state evaluation metrics is explored, balancing between optimistic strategies that favor winning and pessimistic strategies that guard against losing.peer-reviewe

A general-purpose expressive algorithm for room-based environments

This paper presents a generative architecture for general-purpose room layouts that can be treated as geometric definitions of dungeons, mansions, shooter levels and more. The motivation behind this work is to provide a design tool for virtual environments that combines aspects of controllability, expressivity and generality. Towards that end, a two-tier level representation is realized, with a graph-based design specification constraining and guiding the generated geometries, facilitated by constrained evolutionary search. Expressivity is secured through quality-diversity search which can provide the designer with a broad variety of level layouts to choose from. Finally, the generator is general-purpose as it can produce layouts based on different types of static grid structures or as freeform, curved structures through an adaptive Voronoi diagram that is evolved along with the level itself. The method is tested on a variety of design specifications and grid types, and results show that even with complex design constraints or malleable grids the algorithm can produce a broad variety of levels.peer-reviewe

Transforming scholarship in the archives through handwritten text recognition:Transkribus as a case study

Purpose: An overview of the current use of handwritten text recognition (HTR) on archival manuscript material, as provided by the EU H2020 funded Transkribus platform. It explains HTR, demonstrates Transkribus, gives examples of use cases, highlights the affect HTR may have on scholarship, and evidences this turning point of the advanced use of digitised heritage content. The paper aims to discuss these issues. - Design/methodology/approach: This paper adopts a case study approach, using the development and delivery of the one openly available HTR platform for manuscript material. - Findings: Transkribus has demonstrated that HTR is now a useable technology that can be employed in conjunction with mass digitisation to generate accurate transcripts of archival material. Use cases are demonstrated, and a cooperative model is suggested as a way to ensure sustainability and scaling of the platform. However, funding and resourcing issues are identified. - Research limitations/implications: The paper presents results from projects: further user studies could be undertaken involving interviews, surveys, etc. - Practical implications: Only HTR provided via Transkribus is covered: however, this is the only publicly available platform for HTR on individual collections of historical documents at time of writing and it represents the current state-of-the-art in this field. - Social implications: The increased access to information contained within historical texts has the potential to be transformational for both institutions and individuals. - Originality/value: This is the first published overview of how HTR is used by a wide archival studies community, reporting and showcasing current application of handwriting technology in the cultural heritage sector

Familial hypercholesterolaemia in children and adolescents from 48 countries: a cross-sectional study

Background: Approximately 450 000 children are born with familial hypercholesterolaemia worldwide every year, yet only 2·1% of adults with familial hypercholesterolaemia were diagnosed before age 18 years via current diagnostic approaches, which are derived from observations in adults. We aimed to characterise children and adolescents with heterozygous familial hypercholesterolaemia (HeFH) and understand current approaches to the identification and management of familial hypercholesterolaemia to inform future public health strategies. Methods: For this cross-sectional study, we assessed children and adolescents younger than 18 years with a clinical or genetic diagnosis of HeFH at the time of entry into the Familial Hypercholesterolaemia Studies Collaboration (FHSC) registry between Oct 1, 2015, and Jan 31, 2021. Data in the registry were collected from 55 regional or national registries in 48 countries. Diagnoses relying on self-reported history of familial hypercholesterolaemia and suspected secondary hypercholesterolaemia were excluded from the registry; people with untreated LDL cholesterol (LDL-C) of at least 13·0 mmol/L were excluded from this study. Data were assessed overall and by WHO region, World Bank country income status, age, diagnostic criteria, and index-case status. The main outcome of this study was to assess current identification and management of children and adolescents with familial hypercholesterolaemia. Findings: Of 63 093 individuals in the FHSC registry, 11 848 (18·8%) were children or adolescents younger than 18 years with HeFH and were included in this study; 5756 (50·2%) of 11 476 included individuals were female and 5720 (49·8%) were male. Sex data were missing for 372 (3·1%) of 11 848 individuals. Median age at registry entry was 9·6 years (IQR 5·8-13·2). 10 099 (89·9%) of 11 235 included individuals had a final genetically confirmed diagnosis of familial hypercholesterolaemia and 1136 (10·1%) had a clinical diagnosis. Genetically confirmed diagnosis data or clinical diagnosis data were missing for 613 (5·2%) of 11 848 individuals. Genetic diagnosis was more common in children and adolescents from high-income countries (9427 [92·4%] of 10 202) than in children and adolescents from non-high-income countries (199 [48·0%] of 415). 3414 (31·6%) of 10 804 children or adolescents were index cases. Familial-hypercholesterolaemia-related physical signs, cardiovascular risk factors, and cardiovascular disease were uncommon, but were more common in non-high-income countries. 7557 (72·4%) of 10 428 included children or adolescents were not taking lipid-lowering medication (LLM) and had a median LDL-C of 5·00 mmol/L (IQR 4·05-6·08). Compared with genetic diagnosis, the use of unadapted clinical criteria intended for use in adults and reliant on more extreme phenotypes could result in 50-75% of children and adolescents with familial hypercholesterolaemia not being identified. Interpretation: Clinical characteristics observed in adults with familial hypercholesterolaemia are uncommon in children and adolescents with familial hypercholesterolaemia, hence detection in this age group relies on measurement of LDL-C and genetic confirmation. Where genetic testing is unavailable, increased availability and use of LDL-C measurements in the first few years of life could help reduce the current gap between prevalence and detection, enabling increased use of combination LLM to reach recommended LDL-C targets early in life

Reconstructing the attitude of the GRACE-FO mission based on fusion of star sensor, gyroscope and steering mirror data

On May 22, 2018, the Gravity Recovery and Climate Experiment Follow On (GRACE-FO) mission was launched with the goal to map the spatiotemporal variations in the Earth's gravity field and to extend the 15-year monthly mass change observations of its predecessor, the GRACE mission. Similarly to GRACE, the measurement principle of GRACE-FO is based on three different key elements, namely inter-satellite ranging, precise orbit determination and accelerometry. The accurate estimation of the satellites’ attitude has an influence on all three of them. Therefore, any unmodeled errors in the attitude dataset product can propagate to the gravity field solutions and degrade the results. The objectives of this thesis are twofold. Firstly, to analyse the in-flight performance of the GRACE-FO star cameras, fiber-optic gyroscopes, accelerometers and steering mirrors. Secondly, to propose a method that accounts for the instruments' noise and errors and fuses the data, giving an improved attitude solution.The noise and error characteristics of each instrument are determined by examining their measurements in the time and frequency domain, as well as investigating their differences in geographic plots. These analyses are performed for May 2020, when all instruments could provide nominal data. Motivated by the improved attitude quaternions and gravity field results that were obtained from the latest GOCE gradiometer data calibration process, the proposed on-ground attitude reconstruction for GRACE-FO is composed of three elements. The first one is the optimal combination of star camera and steering mirror quaternions by minimizing the weighted residual sum of squares of the elements of the noise quaternions. Within this combination, a set of constant parameters are also estimated that describe the relative alignment of these sensors. The second element is the reconstruction of the satellite angular rates in the frequency domain by applying respectively a highpass and a lowpass filter to the IMU and to the combined star camera and steering mirror derived angular rates. Lastly, the third element is the attitude reconstruction, for which attitude quaternions, resulting from the smooth reconstructed angular rates, are fitted to the optimally combined quaternions by means of a generalised least-squares adjustment.The proposed attitude data fusion method produces an improved attitude solution that incorporates more accurately the noise and error characteristics of the star camera, the steering mirror and the IMU measurements. At the level of quaternions, it performs better than the official method, which is based on Kalman filtering, with noticeable improvements at frequencies above 10 mHz. However, based on a comparison of the corresponding derived antenna offset correction for range rate, very minor improvements are expected at the level of the gravity field. This is due to the K/Ka-band ranging system noise being the dominant source at the higher frequencies. The findings of this thesis work are valuable for the design of future gravity missions such as the Next Generation Gravity Mission proposed by ESA, for which a redundant accelerometer design is considered. Given the estimated noise characteristics of the above instruments and the proposed angular rate reconstruction method, the most favorable placement of the accelerometers is found to be in the along-track direction. If an accelerometer fails in this configuration, the noise in the required centrifugal and Euler acceleration corrections will be less than that of the laser ranging system.Aerospace Engineering | Space Exploratio

Ανάκτηση τριδιάστατων άκαμπτων και εύκαμπτων αντικειμένων

This dissertation focuses on the problem of 3D object retrieval from large datasets in a near realtime manner. In order to address this task we focus on three major subproblems of the field: (i) pose normalization of rigid 3D models with applications to 3D object retrieval, (ii) non-rigid 3D object description and (iii) search over rigid 3D object datasets based on 2D image queries. Regarding the first of the three subproblems, 3D model pose normalization, three novel pose normalization methods are presented, based on: (i) 3D Reflective Object Symmetry (ROSy) and (ii, iii) 2D Reflective Object Symmetry computed on Panoramic Views (SymPan and SymPan+). All three methods are general purpose 3D model pose normalization methods used to enhance the performance of a rigid 3D object retrieval pipeline.Considering the second subproblem, a non-rigid 3D object retrieval methodology, based on the properties of conformal geometry and graph-based topological information (ConTopo++) has been developed. While graph-based methods are robust to non-rigid object deformations, they require intensive computations which can be reduced by the use of appropriate representations, addressed through geometry-based methods. In this respect, a 3D object retrieval methodology which combines the above advantages in a unified manner, is presented. Furthermore, a string matching strategy for the comparison of graphs that describe 3D objects, is proposed.Regarding the third subproblem a 3D object retrieval method, based on 2D range image queries that represent partial views of real 3D objects, is presented. The complete 3D objects of the database are described by a set of panoramic views and a Bag-of-Visual-Words model is built using SIFT features extracted from them. To address the problem of partial matching, a spatial histogram computation scheme on the panoramic views, is suggested.The methodologies developed and described in this dissertation are evaluated in terms of retrieval accuracy and demonstrated using both quantitative and qualitative measures via an extensive consistent evaluation against state-of-the-art methods on standard datasetsΗ παρούσα διδακτορική διατριβή εστιάζει στο πρόβλημα της ανάκτησης 3Δ αντικειμένων από μεγάλες βάσεις δεδομένων σε σχεδόν πραγματικό χρόνο. Για την αντιμετώπιση του προβλήματος αυτού, η έρευνα επικεντρώνεται σε τρία βασικά υποπροβλήματα του χώρου: (α) κανονικοποίηση θέσης άκαμπτων 3Δ μοντέλων με εφαρμογές στην ανάκτηση 3Δ αντικειμένων, (β) περιγραφή εύκαμπτων 3Δ αντικειμένων και (γ) αναζήτηση από βάσεις δεδομένων 3Δ αντικειμένων βασιζόμενη σε 2Δ εικόνες-ερώτησης.Σχετικά με το πρώτο υποπρόβλημα, την κανονικοποίηση θέσης 3Δ μοντέλων, παρουσιάζονται τρεις νέες μέθοδοι οι οποίες βασίζονται στις εξής αρχές: (α) Τριδιάστατη Ανακλαστική Συμμετρία Αντικειμένου (ROSy) και (β, γ) Διδιάστατη Ανακλαστική Συμμετρία Αντικειμένου υπολογιζόμενη επί Πανοραμικών Προβολών (SymPan και SymPan+). Και οι τρεις μέθοδοι αποτελούν γενικού σκοπού μεθόδους κανονικοποίησης 3Δ μοντέλων και χρησιμοποιούνται για να αυξήσουν την απόδοση μιας διαδικασίας ανάκτησης 3Δ αντικειμένων.Όσον αφορά το δεύτερο υποπρόβλημα, αναπτύχθηκε μια μέθοδος ανάκτησης εύκαμπτων 3Δ αντικειμένων, η οποία συνδυάζει τις ιδιότητες της σύμμορφης γεωμετρίας και της τοπολογικής πληροφορίας βασιζόμενης σε γράφους, με ενιαίο τρόπο (ConTopo++). Ενώ οι μέθοδοι που βασίζονται σε γράφους είναι εύρωστες ως προς τις παραμορφώσεις εύκαμπτων αντικειμένων, απαιτούν εντατικούς υπολογισμούς, οι οποίοι ωστόσο μπορούν να μειωθούν με τη χρήση κατάλληλων αναπαραστάσεων, μέσω μεθόδων που βασίζονται στην γεωμετρία. Επιπλέον, προτείνεται μια στρατηγική συνταιριασμού συμβολοσειρών, για τη σύγκριση των γράφων που αναπαριστούν 3Δ αντικείμενα.Σχετικά με το τρίτο υποπρόβλημα, παρουσιάζεται μια μέθοδος ανάκτησης 3Δ αντικειμένων, βασιζόμενη σε 2Δ εικόνες-ερώτησης, οι οποίες αντιπροσωπεύουν προβολές πραγματικών 3Δ αντικειμένων. Τα πλήρη 3Δ αντικείμενα της βάσης δεδομένων περιγράφονται από ένα σύνολο πανοραμικών προβολών και ένα μοντέλο Bag-of-Visual-Words δημιουργείται χρησιμοποιώντας τα χαρακτηριστικά SIFT που προέρχονται από αυτά. Για να αντιμετωπιστεί το πρόβλημα της μερικής ταύτισης, προτείνεται ένα σχήμα υπολογισμού χωρικών ιστογραμμάτων από τις πανοραμικές προβολές.Οι μεθοδολογίες που αναπτύχθηκαν και περιγράφονται στην παρούσα διατριβή αξιολογούνται όσον αφορά την ακρίβεια ανάκτησης και παρουσιάζονται κάνοντας χρήση ποσοτικών και ποιοτικών μέτρων μέσω μιας εκτεταμένης και συνεκτικής αξιολόγησης σε σχέση με μεθόδους τρέχουσας τεχνολογικής στάθμης επάνω σε τυποποιημένες βάσεις δεδομένων

Ensemble of PANORAMA-based convolutional neural networks for 3D model classification and retrieval

A novel method for the classification and retrieval of 3D models is proposed; it exploits the 2D panoramic view representation of 3D models as input to an ensemble of convolutional neural networks which automatically compute the features. The first step of the proposed pipeline, pose normalization is performed using the SYMPAN method, which is also computed on the panoramic view representation. In the training phase, three panoramic views corresponding to the major axes, are used for the training of an ensemble of convolutional neural networks. the panoramic views consist of 3-channel images, containing the Spatial Distribution Map, the Normals’ Deviation Map and the magnitude of the Normals’ Devation Map Gradient Image. The proposed method aims at capturing feature continuity of 3D models, while simultaneously minimizing data preprocessing via the construction of an augmented image representation. It is extensively tested in terms of classification and retrieval accuracy on two standard large scale datasets: ModelNet and ShapeNet

Sporadic Pituitary Stalk Hemangioblastoma: A Rare Case Report and Review of the Literature

Supratentorial hemangioblastomas have rarely been described in the literature. Pituitary stalk hemangioblastomas are extremely rare and almost always are associated with von Hippel Lindau disease. Herein, we report a sporadic case of pituitary stalk hemangioblastoma in a 36-year-old male and review the current literature regarding this pathology. In our case, complete resection of the lesion was achieved using the transglabellar approach

Reproducibility of self-compacting concrete batches between two different EU laboratories

Self Compacting Concrete (SCC) offers a wide variety of advantages during casting. Considering the worldwide uniformity of guidelines concerning the composition and casting instructions for the production of fresh SCC, there is a need to explore the reproducibility of similar self-compacting concrete batches between different countries. In the present study, the fresh properties of similar SCC batches produced in two different laboratories of the European Union are being compared and evaluated