105 research outputs found
Residual Nominal Automata
No full textWe are motivated by the following question: which nominal languages admit an active learning algorithm? This question was left open in previous work, and is particularly challenging for languages recognised by nondeterministic automata. To answer it, we develop the theory of residual nominal automata, a subclass of nondeterministic nominal automata. We prove that this class has canonical representatives, which can always be constructed via a finite number of observations. This property enables active learning algorithms, and makes up for the fact that residuality - a semantic property - is undecidable for nominal automata. Our construction for canonical residual automata is based on a machine-independent characterisation of residual languages, for which we develop new results in nominal lattice theory. Studying residuality in the context of nominal languages is a step towards a better understanding of learnability of automata with some sort of nondeterminism
Separation and Renaming in Nominal Sets
No full textNominal sets provide a foundation for reasoning about names. They are used primarily in syntax with binders, but also, e.g., to model automata over infinite alphabets. In this paper, nominal sets are related to nominal renaming sets, which involve arbitrary substitutions rather than permutations, through a categorical adjunction. In particular, the left adjoint relates the separated product of nominal sets to the Cartesian product of nominal renaming sets. Based on these results, we define the new notion of separated nominal automata. We show that these automata can be exponentially smaller than classical nominal automata, if the semantics is closed under substitutions
Native American ethnobotany
No full text"Native American Ethnobotany is a comprehensive account of the plants used by Native American peoples for medicine, food, and other purposes. The author, anthropologist Daniel E. Moerman, has devoted more than 25 years to the compilation of the ethnobotanical knowledge slowly gathered over the course of many centuries and recorded in hundreds of firsthand studies of American Indians made over the past 150 years. This research has yielded a treasure-trove of information whose magnitude will surprise even those familiar with the anthropological and botanical literature: it documents Native American use of 4029 kinds of plants with a total of 44,691 usages."--BOOK JACKET
Empirical Studies on Asset Pricing and Banking in the Euro Area
No full textEuropean capital markets have changed dramatically over the last couple of years. Due to the harmonization of monetary and policy rules and the elimination of exchange rate risk (through the introduction of the euro) countries in the European Monetary Union (EMU) are becoming more integrated. In this thesis the author tries to determine the consequences of this integration process for asset pricing in the euro area. The most important conclusion, which is a central theme of the thesis, is that the characteristics of financial markets in the euro area have been changing. In other words, investors and researchers cannot base their expectations on the (long) historical evidence of these markets, because the structural changes have a clear impact on the characteristics of the markets. For example, the author shows that industry information has become more valuable in terms of portfolio diversification benefits than country information, especially after the introduction of the euro, which contrasts with the literature of the 90’s. Therefore, investors should change their view in the euro area to a sector-based approach. Most institutional investors, which are the biggest investors in the euro area, have already changed their view into a sector-based approach. As a consequence, euro area portfolio managers are nowadays tracking sector indices instead of country indices. One of the chapters in part II of the thesis shows the implications of that change for the banking sector. Stock returns of big banks have become more correlated, while this is not the case for smaller banks. The author argues that this is not a result of a similar performance or product portfolio of these banks, but is likely the result of the change in perspective of most euro area investors. Next to these topics, the thesis also covers different asset pricing models (Fama and French three factor models for the euro area and an international asset pricing model that provides evidence of a significant risk premium for inflation risk) and an innovative measure for contagion among European banks.Gerard Moerman (1976) received his Master’s degree in Econometrics from the Erasmus University Rotterdam in 1999. In October 1999 he joined ERIM to carry out his doctoral research at the Financial Management department of the RSM Erasmus University. During this time he spent seven months at the European Central Bank (Frankfurt) as an economist at the General Economic Research Department. Some of his work has been published (Journal of International Money and Finance) and presented at international conferences. His current research interests include empirical asset pricing, banking and financial integration. Also, he has reviewed several papers, e.g. for the Journal of International Money and Finance and the ECB working paper series. As of February 2005 he joined AEGON Asset Management as Investment Strategist.In dit proefschrift staan de aandelenmarkten uit het eurogebied centraal. De belangrijkste conclusie, die als rode draad door het proefschrift loopt, is dat het Europese integratieproces een aantoonbare invloed heeft op de Europese aandelenmarkten. Deze these wordt vanuit verschillende perspectieven onderzocht.
Nieuwe modellen voor de waardering van aandelen
Een direct gevolg van deze algemene conclusie is dat modellen die gebruikt worden om de prijs van een aandeel te bepalen opnieuw bestudeerd moeten worden. Deze worden namelijk meestal getest op basis van een lange reeks van historische gegevens. Het is echter niet verstandig de verwachtingen te baseren op de historische gegevens alleen, omdat “de spelregels” in en tussen de aandelenmarkten uit het eurogebied veranderd zijn. Bijvoorbeeld, de introductie van de euro heeft als direct gevolg dat het wisselkoersrisico tussen eurolanden is verdwenen. Moerman test één van de meest gebruikte modellen voor het prijzen van aandelen (gebaseerd op het onderzoek van Fama en French) en laat zien dat het Europese model steeds meer terrein wint ten opzichte van een apart model voor ieder land. Hieruit kan geconcludeerd worden dat aandelenmarkten meer financiële integratie laten zien.
Betere risicospreiding over sectoren dan over landen
Veel pensioenfondsen en andere vermogensbeheerders proberen hun aandelenportefeuille zo slim mogelijk op te zetten door de beleggingen te spreiden, waardoor de verhouding tussen het rendement en het risico beter is. Onderzoek uit de jaren negentig toonde aan dat een spreiding over verschillende landen het meest succesvol was. Moerman laat echter zien dat deze resultaten heden ten dage niet meer opgaan voor het eurogebied. Door het integratieproces laten de aandelenindices van landen steeds meer dezelfde beweging zien, waardoor het spreiden minder diversificatievoordelen oplevert. Spreiding over verschillende sectoren is verstandiger.
Gevolgen van deze andere aanpak
Uit een rapport van de Europese Centrale Bank blijkt dat veel institutionele beleggers inderdaad hun landenaanpak voor het eurogebied hebben omgezet naar een sectoraanpak. Een direct gevolg hiervan is dat de portefeuillemanagers van deze investeerders, die proberen de index te verslaan, nu worden afgerekend op een sectorindex in plaats van een landenindex. Daardoor neemt de vraag naar de grotere bedrijven binnen een sector toe, omdat de portefeuillemanagers meestal niet teveel van de index mogen afwijken. In zijn proefschrift onderzoekt Moerman dit voor de Europese bankensector. Het blijkt dat de grotere aandelen in de bankensector inderdaad steeds meer op elkaar gaan lijken qua rendementen. Dit kan niet verklaard worden door de resultaten van banken, aangezien deze sterk verschillen, maar lijken dus afkomstig te zijn van veranderingen in de vraag door de wijziging in aanpak van grote beleggers. Dit geeft derhalve een extra motivatie voor banken om door middel van fusies tot het topsegment te behoren. “Een mogelijke strategie voor banken is om te streven bij de grootste banken binnen Europa te horen om zodoende goedkoper toegang tot kapitaal via de financiële markten te krijgen”, zo stelt Moerman. “Dit geeft een verklaring voor de overnamepogingen die momenteel plaatsvinden in deze sector, zoals het bod ABN op Antonveneta en de geruchten tussen HVB en Unicredito”
A survey on machine learning-based performance improvement of wireless networks: PHY, MAC and network layer
No full textThis paper presents a systematic and comprehensive survey that reviews the latest research efforts focused on machine learning (ML) based performance improvement of wireless networks, while considering all layers of the protocol stack: PHY,MAC and network. First, the related work and paper contributions are discussed, followed by providing the necessary background on data-driven approaches and machine learning to help non-machine learning experts understand all discussed techniques. Then, a comprehensive review is presented on works employing ML-based approaches to optimize the wireless communication parameters settings to achieve improved network quality-ofservice (QoS) and quality-of-experience (QoE).We first categorize these works into: radio analysis, MAC analysis and network prediction approaches, followed by subcategories within each. Finally, open challenges and broader perspectives are discussed.Signal Processing System
Determining the sub-cellular localization of proteins within Caenorhabditis elegans body wall muscle.
No full textDetermining the sub-cellular localization of a protein within a cell is often an essential step towards understanding its function. In Caenorhabditis elegans, the relatively large size of the body wall muscle cells and the exquisite organization of their sarcomeres offer an opportunity to identify the precise position of proteins within cell substructures. Our goal in this study is to generate a comprehensive "localizome" for C. elegans body wall muscle by GFP-tagging proteins expressed in muscle and determining their location within the cell. For this project, we focused on proteins that we know are expressed in muscle and are orthologs or at least homologs of human proteins. To date we have analyzed the expression of about 227 GFP-tagged proteins that show localized expression in the body wall muscle of this nematode (e.g. dense bodies, M-lines, myofilaments, mitochondria, cell membrane, nucleus or nucleolus). For most proteins analyzed in this study no prior data on sub-cellular localization was available. In addition to discrete sub-cellular localization we observe overlapping patterns of localization including the presence of a protein in the dense body and the nucleus, or the dense body and the M-lines. In total we discern more than 14 sub-cellular localization patterns within nematode body wall muscle. The localization of this large set of proteins within a muscle cell will serve as an invaluable resource in our investigation of muscle sarcomere assembly and function
Werkwijze voor het vervaardigen van een chemische inrichting
No full textDelft University of Technolog
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