Studying the brain from adolescence to adulthood through sparse multi-view matrix factorisations

Men and women differ in specific cognitive abilities and in the expression of several neuropsychiatric conditions. Such findings could be attributed to sex hormones, brain differences, as well as a number of environmental variables. Existing research on identifying sex-related differences in brain structure have predominantly used cross-sectional studies to investigate, for instance, differences in average gray matter volumes (GMVs). In this article we explore the potential of a recently proposed multi-view matrix factorisation (MVMF) methodology to study structural brain changes in men and women that occur from adolescence to adulthood. MVMF is a multivariate variance decomposition technique that extends principal component analysis to "multi-view" datasets, i.e. where multiple and related groups of observations are available. In this application, each view represents a different age group. MVMF identifies latent factors explaining shared and age-specific contributions to the observed overall variability in GMVs over time. These latent factors can be used to produce low-dimensional visualisations of the data that emphasise age-specific effects once the shared effects have been accounted for. The analysis of two datasets consisting of individuals born prematurely as well as healthy controls provides evidence to suggest that the separation between males and females becomes increasingly larger as the brain transitions from adolescence to adulthood. We report on specific brain regions associated to these variance effects.Comment: Submitted to the 6th International Workshop on Pattern Recognition in Neuroimaging (PRNI

Control of processer with time delays

The main goal of research -to simulate and investigate the processes of automatic management systems with significant automatic delays. In master’s final work, is investigation of managing systems with significant time delays. Investigation was done by simulation carried out in the environment of Matlab/Simulak.To model the processes, transmission functions in which time delay duration is much greater, than in comparison with the resultant steady of time were used. Work consists of investigation of operation in-one management systems. Standard PI, PID, regulators and time delay-compensating system, were used. Final work consists of quality evaluation of statistical indexes of transitional processes. Research presents management system response curves, transitional processes quality indexes and their statistical evaluation. Research findings are summarized in the evaluation

Ernesto Laclau populizmo teorija ir jos operacionalizacija: politinės partijos „Drąsos kelias“ atvejis

This article aims to explain the rise of the Lithuanian political party “The Way of Courage” using Ernesto Laclau’s discourse theory of populism, in which populism is understood as a logic of collective identity formation. The advantages of this theoretical approach are revealed by comparing it with other tendencies of conceptualizing populism. In addition, this article is an attempt to solve the main disadvantage of E. Laclau’s theory – its high level of abstractness, understood as an obstacle for operationalization. Therefore, various possibilities of combining E. Laclau’s theory with other methodological perspectives are discussed, and a new research model is suggested, which is later applied in the discourse analysis of the political party “The Way of Courage.”Straipsnyje politinės partijos „Drąsos kelias“ iškilimui aiškinti pritaikoma Ernesto Laclau diskursyvi populizmo teorija, kuria remiantis populizmas suprantamas kaip kolektyvinio identiteto formavimosi logika. Šio teorinio požiūrio pranašumai atskleidžiami, lyginant jį su kitomis populizmo konceptualizavimo kryptimis. Taip pat mėginamas įveikti vienas iš šios teorijos trūkumų – per didelis abstraktumas, trukdantis pritaikyti ją empiriniams tyrimams. Straipsnyje aptariamos teorijos operacionalizavimo galimybės derinant ją su kitomis metodologinėmis perspektyvomis bei pasiūlomas naujas tyrimo modelis, kuris ir pritaikomas populistinės politinės partijos „Drąsos kelias“ atvejo tyrime

Human vs. Machine: Disposition Effect among Algorithmic and Human Day Traders

This paper studies whether and why algorithmic traders exhibit one of the most broadlydocumented behavioral puzzles – the disposition effect. We use trade data from the NASDAQ Copenhagen Stock Exchange merged with the weather data. We find that on average, the disposition effect for human traders is substantial and increases significantly on colder days, while for similarly-trading algorithms, it is insignificant and insensitive to the weather. This provides causal evidence of the link between human psychology and the disposition effect and suggests that algorithms can reduce psychology-related human errors. Considering the ongoing AI adoption, this may have broad implications.publishedVersio

Autonomous Systems

The ubiquity of digital media provides an unprecedented possibility to redefine the process and methods of design. Through experience from a series of creative projects, I investigate how certain aspects of the web allow for design to attain a degree of autonomy, thus producing results that go beyond anticipation and expertise of the author. Utilizing an unlimited capacity to store the content and retrieve immediate feedback, the designer’s role can be shifted to that of an initiator defining rules and boundaries, from which the process can evolve independently based on the input of users and data. The design output in such conditions is the development of schemes in which the author remains, but is marginalized as a producer – consciously restraining his level of control. Rather then struggling to add something singular to the bottomless pit of information, the designer is relegated in the role of medium: collecting and recombining the bits of fragmented data into the structures conveying meaning

Versatile femtosecond optical parametric oscillator frequency combs for metrology

This thesis addresses the development of broadly tunable, high repetition rate frequency combs in the mid-IR region. A novel PPKTP crystal design was used to provide phasematching for parametric oscillation and simultaneously give efficient pump+idler sum-frequency generation (SFG). This innovation enabled a fully stabilized idler comb from a 333-MHz femtosecond optical parametric oscillator to be generated in which the carrier envelope offset frequency fCEO together with the repetition frequency fREP were stabilised. This OPO platform was then extended to demonstrate, via harmonic pumping, a fully stabilized 1-GHz OPO frequency comb from a 333-MHz pump laser. Next, an alternative route to a 1-GHz OPO comb was investigated by synchronously pumping an OPO directly with a 1-GHz Ti:sapphire laser. Here the comb was fully stabilized for the signal, idler and pump pulses by using a narrow linewidth CW diode laser developed for the project and whose design is also presented. A further increase in the comb mode spacing was performed with a Fabry-Pérot cavity. A stabilised cavity was used to filter 1.5 m signal pulses from a 333-MHz repetition rate OPO frequency comb to yield a 10-GHz comb. The length of the Fabry-Pérot cavity was dither locked to a single-frequency ECDL and later on directly to the OPO frequency comb. Finally the 333-MHz OPO comb was demonstrated in an optical frequency metrology experiment. The frequency comb mode number and the absolute frequency of a narrow-linewidth CW laser were measured and the performance of the OPO comb was found to be comparable to that of a commercial fibre laser comb used as a benchmark in the experiment