Stochastic Gradient versus Recursive Least Squares Learning

In this paper we perform an in—depth investigation of relative merits of two adaptive learning algorithms with constant gain, Recursive Least Squares (RLS) and Stochastic Gradient (SG), using the Phelps model of monetary policy as a testing ground. The behavior of the two learning algorithms is very different. RLS is characterized by a very small region of attraction of the Self—Confirming Equilibrium (SCE) under the mean, or averaged, dynamics, and “escapesâ€, or large distance movements of perceived model parameters from their SCE values. On the other hand, the SCE is stable under the SG mean dynamics in a large region. However, actual behavior of the SG learning algorithm is divergent for a wide range of constant gain parameters, including those that could be justified as economically meaningful. We explain the discrepancy by looking into the structure of eigenvalues and eigenvectors of the mean dynamics map under the SG learning. As a result of our paper, we express a warning regarding the behavior of constant gain learning algorithm in real time. If many eigenvalues of the mean dynamics map are close to the unit circle, Stochastic Recursive Algorithm which describes the actual dynamics under learning might exhibit divergent behavior despite convergent mean dynamics.constant gain adaptive learning, E—stability, recursive least squares, stochastic gradient learning

Samoorganizace ve směsích surfaktantů a polymerů s komplexní strukturou citlivých ke změně vnějšího prostředí

Title: Self-assembly in mixture of surfactants and stimuli-responsive polymers with complex architecture Author: Anna Bogomolova Department: Physical and Macromolecular Chemistry Supervisor: PhD. Sergey K. Filippov, IMC AS CR, v.v.i. Supervisor's e-mail address: [email protected] Abstract: The issue of construction of complex multi-block copolymers is currently one of the most researched areas. It became a logic consequence of the continuous development in polymer chemistry. Nowadays, a great interest is attracted to multi- responsive block copolymers. As a rule, they consist of hydrophilic, hydrophobic and responsive blocks. That responsive block can be either thermo-sensitive or pH-sensitive as well as sensitive to some other external stimuli. In the present work, we will try to cover topic of stimuli-responsive block copolymers and their interactions with different types of surfactants. Understanding of polymer/surfactant interactions can be a crucial step for future modeling of drug/polymer or protein(DNA)/surfactant interactions. There is a great interest in the investigation of polymer-surfactant interactions. However, while the homopolymer-surfactant interactions are characterized well enough, the same interactions for block copolymers are poorly described. The main development in the latter topic...Název práce: Samoorganizace ve směsích surfaktantů a polymerů s komplexní strukturou citlivých ke změně vnějšího prostředí Autor: Anna Bogomolova Katedra: Fyzikální a makromolekulární chemie Vedoucí doktorské práce: PhD. Sergey K. Filippov, IMC AS ČR, v.v.i. E-mail vedoucího: [email protected] Abstrakt: Problematika syntézy komplexních multi-blokových kopolymerů je v současné době jednou z nejvíce zkoumaných oblastí polymerní chemie, jakožto logický výsledek dlouhodobého vývoje v této oblasti. V současné době je velký zájem o blokové kopolymery citlivé ke změně vnějšího prostředí. Takové kopolymery se zpravidla skládají z hydrofilních, hydrofobních či reaktivních bloků. Jeden z těchto bloků může být termo- nebo pH-senzitivní, popřípadě i citlivý na jiné vnější podněty. V této práci jsme se snažili pokrýt téma kopolymerů citlivých ke změně vnějšího prostředí a jejich interakce s různými typy povrchově aktivních látek (surfaktantů). Pochopení interakcí mezi polymerem a surfaktantem může být rozhodujícím krokem pro budoucí modelování interakcí v systému léčivo/polymer (popřípadě protein)/surfaktant. Zatímco povrchové interakce homopolymerů se surfaktanty jsou popsány poměrně dobře, stejné interakce u blokové kopolymery nebyly příliš zkoumány. Výjimku tvoří molekuly typu Pluronic (blokové kopolymery PEO a...Department of Physical and Macromolecular ChemistryKatedra fyzikální a makromol. chemieFaculty of SciencePřírodovědecká fakult

Internal nanoparticle structure of temperature-responsive self-assembled PNIPAM-b-PEG-b-PNIPAM triblock copolymers in aqueous solutions: NMR, SANS and light scattering studies

In this study we report detailed information on the internal structure of PNIPAM-b-PEG-b-PNIPAM nanoparticles formed from self-assembly in aqueous solutions upon increase in temperature. NMR spectroscopy, light scattering and small-angle neutron scattering (SANS) were used to monitor different stages of nanoparticle formation as a function of temperature, providing insight into the fundamental processes involved. The presence of PEG in a copolymer structure significantly affects the formation of nanoparticles, making their transition to occur over a broader temperature range. The crucial parameter that controls the transition is the ratio of PEG/PNIPAM. For pure PNIPAM, the transition is sharp; the higher the PEG/PNIPAM ratio results in a broader transition. This behavior is explained by different mechanisms of PNIPAM block incorporation during nanoparticle formation at different PEG/PNIPAM ratios. Contrast variation experiments using SANS show that the structure of nanoparticles above cloud point temperatures for PNIPAM-b-PEG-b-PNIPAM copolymers is drastically different from the structure of PNIPAM mesoglobules. In contrast with pure PNIPAM mesoglobules, where solid-like particles and chain network with a mesh size of 1-3 nm are present; nanoparticles formed from PNIPAM-b-PEG-b-PNIPAM copolymers have non-uniform structure with “frozen” areas interconnected by single chains in Gaussian conformation. SANS data with deuterated “invisible” PEG blocks imply that PEG is uniformly distributed inside of a nanoparticle. It is kinetically flexible PEG blocks which affect the nanoparticle formation by prevention of PNIPAM microphase separation

О международном опыте формирования информационно-статистических ресурсов поддержки социальных программ, направленных на обеспечение интересов детей

The article reviews practices of developed countries with regard to creating inter-agency resources on child and family statistics to monitor and analyze social well-being of these groups of citizens. This type of analysis is essential for developing state policy and specific support programmes for children and families, to monitor the programmes’ implementation and subsequent estimation of the results. The quality of information resource has a strong influence on the results of state programmes. Usually statistical resources with data on children and families with children are developed on the basis of state statists and are co-created by all the agencies responsible for enforcement of rights and legally protected interests of children. They include integrated plans and reports on programmes of federal agencies, regional and local authorities, focused on advancement of children and families with children. To monitor indices of goals and results with regard to every stage of the social programmes implementation, a special section of interagency statistical resources should be separated. Authorized agency-coordinators develop thematic classifications, methods of observation and calculation of the indicators in order to integrate the data coming from different sources. Uniform standards for the presentation of statistical data by government agencies, production discipline, general statistical culture ensure harmonization of data collection methods and integration of indicators, which allows for systematic and comparative analysis. National universities actively participate in the development of techniques for analysis of family and childhood-related issues, studying the dynamics of indicators, creation of research models. The authors of this article emphasize the importance of openness and accessibility of statistical resources that enlighten the society about state support policies for children and families with children; it provides general public with a possibility to compare social programmes and their implementation results at regional and municipal levels. Foreign experience can be useful for creating a similar statistical resource in Russia within the framework of the « Russian National Children’s Strategy for 2012-2017».В статье рассматривается практика развитых стран мира в области формирования межведомственных ресурсов детской и семейной статистики, используемых для мониторинга и анализа социального благополучия этой группы граждан. Такой анализ необходим при разработке государственной политики и конкретных программ помощи детям и семьям, для контроля хода реализации программ и последующей оценки их результатов. Качество информационного ресурса в значительной мере влияет на результаты государственных программ. Как правило, статистические ресурсы, содержащие сведения о детях и семьях с детьми, разрабатываются на основе данных государственной статистики и формируются совместно всеми ведомствами, в чью сферу ответственности входит обеспечение соблюдения прав и законных интересов детей. В их составе интегрированы планы и отчеты по программам федеральных ведомств, региональных и местных органов власти, направленным на улучшение положения детей и семей с детьми. Для мониторинга индикаторов целей и результатов каждого этапа реализации социальных программ необходимо выделение специального раздела межведомственных статистических ресурсов. Уполномоченные ведомства-координаторы разрабатывают тематические классификаторы, методики наблюдения и расчета показателей с целью интеграции данных, поступающих из разных источников. Единые стандарты представления статистических данных государственными ведомствами, производственная дисциплина, общая статистическая культура обеспечивают гармонизацию методов сбора информации и интеграцию показателей, что позволяет проводить системный и сравнительный анализ. В разработке методики анализа проблем семьи и детства, изучении динамики показателей, создании моделей исследования принимают участие университеты. Авторы статьи подчеркивают значимость открытости и доступности статистических ресурсов, что повышает информированность населения о политике государства по поддержке детей и семей с детьми, позволяет сравнивать социальные программы и результаты их реализации в разных регионах страны и на местах. Зарубежный опыт может быть полезен для формирования аналогичного статистического ресурса в России в рамках реализации «Национальной стратегии действий в интересах детей на 2012-2017 годы»

Essays in Heterogeneous Learning

5 Abstract Essays in Heterogeneous Learning by Anna Bogomolova My dissertation makes a contribution to the …eld of heterogeneous adaptive learning in macroeconomic models. This contribution is presented in the form of three research papers that constitute di¤erent chapters of my thesis. In the …rst chapter of my dissertation, "E-stability That Does Imply Learnability", I provide criteria and su¢ cient conditions for the stability of a structurally heterogeneous economy under the heterogeneous learning of agents, extending the results of Honkapohja and Mitra [36], Bogomolova and Kolyuzhnov [5], and Kolyuzhnov [40]. I provide general criteria (in terms of the corresponding Jacobian matrices) for stability under heterogeneous mixed RLS/SG learning for four classes of models: models without lags and with lags of the endogenous variable and with t- or t 1- dating of expectations, and provide su¢ cient conditions for stability for some simpler cases, where simpli…cations include either the diagonal structure of the shock process behaviour or the heterogeneous RLS learning. I also provide su¢ cient conditions for stability in terms of the structural heterogeneity independent of heterogeneity in learning ( -stability) in terms of E-stability of a suitably de…ned aggregate economy for all four classes of models..

Self-Assembly in Mixture of Surfactants and Stimuli-Responsive Polymers with Complex Architecture

Title: Self-assembly in mixture of surfactants and stimuli-responsive polymers with complex architecture Author: Anna Bogomolova Department: Physical and Macromolecular Chemistry Supervisor: PhD. Sergey K. Filippov, IMC AS CR, v.v.i. Supervisor's e-mail address: [email protected] Abstract: The issue of construction of complex multi-block copolymers is currently one of the most researched areas. It became a logic consequence of the continuous development in polymer chemistry. Nowadays, a great interest is attracted to multi- responsive block copolymers. As a rule, they consist of hydrophilic, hydrophobic and responsive blocks. That responsive block can be either thermo-sensitive or pH-sensitive as well as sensitive to some other external stimuli. In the present work, we will try to cover topic of stimuli-responsive block copolymers and their interactions with different types of surfactants. Understanding of polymer/surfactant interactions can be a crucial step for future modeling of drug/polymer or protein(DNA)/surfactant interactions. There is a great interest in the investigation of polymer-surfactant interactions. However, while the homopolymer-surfactant interactions are characterized well enough, the same interactions for block copolymers are poorly described. The main development in the latter topic..

Optimální pravidla monetární politiky: problém stability za heterogenního učení

In this paper we extend the analysis of optimal monetary policy rules in terms of stability of the economy, started by Evans and Honkapohja (2003), to the case of heterogeneous learning

Postačující podmínky a nutné podmínky pro .delta.-stabilitu

We provide sufficient conditions and necessary conditions for stability of an economy under structurally heterogeneous mixed recursive least squares/stochastic gradient learning of agents with possibly different degrees of inertia